[tt] Tierney Lab: How Nigh Is the End?

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Tierney Lab: How Nigh Is the End?
Predictions for Geysers, Marriages, Poker Streaks and the Human Race
http://tierneylab.blogs.nytimes.com/2007/07/16/how-nigh-is-the-end-predictions-for-geysers-marriages-poker-streaks-and-the-human-race/

7.6.16,  8:11 pm
By John Tierney

Imagine you have just landed on another planet and entered Geyser
Intergalactic Park. You know nothing about geysers except that they
sometimes start shooting liquid and sometimes stop. You see two
active geysers, each with a digital stopwatch next to it recording
how long it's been shooting. One geyser has been shooting for 100
million years. The other has been shooting for 10 seconds.

Can you predict which of these geysers will stop first?

You may think there's an easy answer, but it's not so clear to the
philosophers and probability experts who have been debating the
predictions of J. Richard Gott III, the Princeton physicist whom I
discuss in my Findings column. He says you can make forecasts with
95-percent certainty about the likely longevity of the human race -
or your marriage, or your winning streak at the poker table --
simply by looking at how long it has existed. The longer something's
been around, the longer he expects it to last.

By that logic, you should expect the 10-second geyser to stop first,
but it's not so simple, as Bradley Monton and Brian Kierland explain
in an excellent article in the Philosophical Quarterly. These
philosophers - at the University of Colorado and the University of
Missouri, respectively - took a long look at the debate over Dr.
Gott's forecasting method.

Dr. Gott's Copernican Formula assumes that whatever you're observing
is unlikely to still be in the first one-fortieth of its lifespan,
so if it's already been around for x amount of time, it's unlikely
to last an additional 39x amount of time. Conversely, it's probably
not very close to its demise -- - it's probably still in the first
39/40 of its total lifespan, not in the final 1/40 -- so you can
predict that its remaining life is likely to be at least 1/39th of
x.

Dr. Gott applied his formula to the plays and musicals that were
open on Broadway the day his original paper was published in Nature
in 1993. Of the 44 Broadway productions, 40 have closed within the
forecast limits (including "Cats," then being advertised as "now and
forever.") Depending on what happens with the remaining four - none
is yet near its upper limit - Dr. Gott's accuracy rate will be
somewhere between 90 and 100 percent, which jibes nicely with the
95-percent accuracy rate that his formula is supposed to yield.

He has had other successes, too, and says he hasn't seen the formula
fail yet, but he acknowledges certain obvious limitations. Using
just the Copernican Formula, you'd predict that a 10-year-old dog is
likely to live longer than for a two-month-old puppy. If you have
other information available - like the average lifespan of a dog -
then you can use that to make better predictions.

Nor does Dr. Gott's method work in every situation. Suppose you're
at a wedding and observe that a couple has been married for
precisely 1 minute. Could you predict that their marriage is
unlikely to last more than 39 additional minutes? No, because you've
been invited to observe the beginning of this marriage, so you know
you're seeing it at a special point in time. Dr. Gott wouldn't apply
his formula here because it's based on the Copernican Principle -
the assumption that you're not observing something at a special
point in time.

Now let's return to Geyser Intergalactic Park. Does the Copernican
Principle apply here? Can you assume that you're not observing these
geysers at a special point in time? Some of Dr. Gott's critics
insist you can't be sure and therefore cannot make any predictions
about whether the 10-second geyser will stop before the
100-million-year geyser. A strict agnostic could argue that you know
nothing at all about the lifetime of geysers, as Dr. Monton and Dr.
Kierland explain his reasoning:

   Thus, for all you know, almost all geysers last for slightly more
   than 100 million years, and only a very few geysers last for just
   somewhat more than 10 seconds. Also, for all you know, most
   geysers in the park started about 100 million years ago, so it is
   currently commonplace to witness the end of one. Thus, for all
   you know, it is the end of the 10-second geyser that is the
   unusual event. Since you don't have any empirical data, you don't
   know whether to be surprised at witnessing the end of the
   100-million-year geyser or at witnessing the end of the 10-second
   geyser.

Well, an agnostic could claim not to be surprised to see the
100-million-year-old geyser suddenly peter out. But Dr. Monton and
and Dr. Kierland don't buy that reasoning. While the agnostic's
scenario may be one possibility, they write, "there are many other
possibilities where witnessing the end of that geyser is surprising.
It simply seems more likely to us that one of those later
possibilities is the actual one." They proceed through a lengthy
analysis of Bayesian probability and other theories, finding fault
with some aspects Dr. Gott's argument, but ultimately concluding:

   We agree with the core thesis in Gott's argument: in many
   circumstances, the greater the present age of a process, the more
   likely a longer future duration. What makes Gott's argument so
   fascinating is that one can generate predictions of future
   longevity based on minimal empirical information: the only
   empirical input is the present age of the process.

I asked Dr. Monton to offer a few more thoughts to readers of this
blog about the implications of what he calls the "Gott-like shift"
in the way you calculate probabilities once you consider how long
something has been around. Here's what Dr. Monton had to say:

   Think about relationships -- while one wouldn't want to use
   exactly the Copernican Formula to predict how long one's
   relationship is going to last, something like the Copernican
   Formula can provide useful guidance. For example, I have friends
   who sometimes fall very hard for a person, after only being with
   them for a short time. Applying a Gott-like shift can (correctly)
   remind one that there's a good chance that the relationship won't
   last very long. Here's a related point: if one hasn't been in a
   relationship very long, and one has a fight, it would be
   reasonable to think that that could foretell the end of the
   relationship. But it would be more unreasonable to think that in
   a situation where one has been in a relationship for a long
   period of time.

   Another example is poker (a game I like to play). When a player
   goes on a winning streak, they often (mistakenly) attribute that
   to their good play, not luck, and think that the winning will
   likely continue. If they remind themselves that the winning
   streak hasn't been going on that long, and apply a Gott-like
   shift, that can give them reason to think that the winning streak
   might not continue.

   One reason I like these examples is that much more sophisticated
   reasoning could come into play, to make more accurate predictions
   than one would get from Gott-like reasoning. (For example,
   there's data on the longevity of relationships, and on what sorts
   of fights end relationships, and a poker player's play can be
   analyzed, to determine to what extent the winnings should be
   attributed to skill.) But in the absence of this sort of
   information or analysis, Gott-like reasoning can nevertheless be
   helpful.

   Oh, and regarding colonizing space, I think Gott is right -- it
   should be a major priority that we work on establishing
   self-sufficient colonies on other planets. Technology hasn't been
   around very long, and in the absence of evidence this should lead
   us to think that it's likely that it won't be around very long in
   the future. But we shouldn't be fatalistic about Copernican
   Principle predictions -- there are things we can do to make it
   more likely that technology-adept intelligent life will continue
   to be around in the future. Besides the obvious things we can do
   (e.g. controlling loose nukes, preventing pandemics),
   establishing self-sufficient colonies will clearly make a
   difference.

I'm all for establishing space colonies, too, and I used to assume
they were our destiny once we evolved a little further. But now Dr.
Gott has pointed out the problem with the common science-fiction
idea that we're just a small, primitive civilization among advanced
ones that are already busy colonizing their galaxies. According to
the Copernican Principle, we're more likely to be living in one of
the universe's larger and longer-lived civilizations (for the same
statistical reason that a randomly chosen American is likely to be
from a town that's larger than the median size -- those large towns
have a disproportionate number of people in them). Since we haven't
yet colonized any other planets, maybe most civilizations never end
up doing so.

In fact, we could assume that the typical civilization reaches our
stage of development, applies the Copernican principle, realizes
that it's 95-percent certain to go extinct unless it takes an
extraordinary step like colonizing other planets -- and then goes
extinct even though it's aware of its eventual doom.

Is that going to happen to us, too? What can we do to beat those
odds?

98 comments so far... [This is all of them.]

1. July 16th, 2007 10:48 pmThe problem with Rich Gott's method is not that 
there's anythingwrong with the assumptions, but that it, since it doesn't 
relyon supplemental data, it encourages people not to take intoaccount 
supplemental data even when it exists. In the examplethat Monton gives 
about his friends and their relationships, thesupplemental data is how 
long their previous relationships havelasted. Different people are 
obviously quite different, and oneought to take this into account when 
figuring out if therelationship will survive a fight after a month. In a 
Bayesianinterpretation, one would talk about assigning an appropriateprior 
probability.In the case of space colonies, there is a lot of 
previousinformation based on the history of exploration and colonizationon 
Earth. I know it's not exactly the same, but there are a lotof 
similarities, based on the difficulty of establishing,supplying, and 
administering far-flung outposts. In this case, Ithink the historical 
record is pretty pessimistic. While somecolonies have succeeded, quite 
often the effort of colonizing isvastly expensive or even ruinous to the 
colonizing power (I'mnot even talking about fighting the natives, but just 
the effortand infrastructure of transporting over long distances). 
TheSpanish colonies in South America are one example. It's possiblethat 
they hastened Spain's fall as a great power rather thandelaying it.
--posted by Benjamin W.

2. July 16th, 2007 10:56 pmI wish I had a more interesting comment to 
make, but all thatcomes to mind is "wow!" That is some amazing stuff.
--posted by Jeff Sachs

3. July 17th, 2007 12:12 amThis seems absurd. Let's define life as 
replicating information.On earth, that has been going on for approximately 
500 millionyears. So using the Copernican assumption, it will continue 
foranother 24,500 million years. Apply Darwinian evolution toreplicating 
information, and you inevitably get complexity. Socomplex replicating 
information will continue on earth for anextremely long time. Will it be 
life as we know it -- aye that'sthe rub!
--posted by dgalbrai

4. July 17th, 2007 12:17 amThe premise of having to secure a Mars colony 
to ensure thesurvival of the human race could be flawed due to 
inadequateapplication of cynicism in regards to human politics 
andhistory.Mankind has been at war with itself constantly, and due 
toindustrialization, we have discovered the ability to do greaterand 
greater, irresponsible harm to ourselves and our environment-- through 
military weaponry of mass destruction, and callousapathy to the 
consequences of our mass consumption.Even in the age of industrialized 
war, the destruction ofthousands of soldiers and innocent plebians have 
not causedleaders & elites to openly shed tears & express regret or 
guiltat their demise.The only reason our world wars stopped at #2, is 
because of thedevelopment of nuclear weapons and mutually assured 
destruction.The elites who devise these wars faced their own 
destruction,and thus there is hesitation. And in this transnational 
economy,elites can gain profit from exploiting other nations, and faceloss 
of assets from wars that are a tad too destructive.However, if such 
warmongering elites can flee the Earth andsafely enjoy their luxuries far 
away, they would not even haveto touch the consequences of destructive, 
irresponsible,decisions such as war, pollution, social chaos, 
culturaldecline, in the course of their exploitation of the Earth, 
itsenvironment, and its people.And/or irresponsible leaders could start a 
doomsday war onEarth, and then flee with their families and their 
equallyguilty advisors & ideologues for a safe colony, without facingthe 
repercussions of their malign management.There are many cynical social and 
political issues to face, aswell as the question of ownership of these 
space colonies. Ishumanity mature enough to grow up? And will it rise to 
theoccasion to identify and resolve persistent social issues 
beforespreading war, injustice, exploitation, and oppression to 
thesecolonies?
--posted by Volt Rare

5. July 17th, 2007 1:29 amThere is no galactic colonization paradox. If 
galacticcolonization is possible, then there will never be more than 
oneintelligent species per galaxy. Any intelligent species thatevolves 
anywhere in any galaxy will either: 1) destroy itselfinstantly (on a 
galactic time scale, that is), or 2) instantly(again, on a galactic time 
scale) colonize the entire galaxy.The first time 2) happens, that is the 
end of the game -- theentire galaxy will be occupied, and no more 
intelligent specieswill evolve. And that one species will always be alone. 
As weseem to be now. So where is the paradox? If galacticcolonization is 
possible all that means is that we must be thefirst (except for an unknown 
number of false starts, which Iwould guess to be in the low double digits 
at worst).And if galactic colonization is not possible, then there is 
noparadox either. In that case the galaxy is riddled withcivilizations, 
none of which have the ability to actually comehere. No problem here 
either!Gott's main argument also seems pretty worthless to me. True, ifyou 
know ABSOLUTELY NOTHING about a phenomenon, then yes, thenif you want to 
know how long it is going to last the best youcan do is make a guess based 
on how long it has already lasted.That much is trivial. But that estimate 
will have to be revised
--probably drastically -- the minute you gain any sort of hardknowledge, 
so really, how important can it be by itself?For example, if I tell you I 
have a pet that is six months old,you can make a very rough guess as to 
how much longer it mightlive. But if I give you further information, for 
example if Itell you that it is a type of animal, like a tortoise, that 
iscapable of living a very long time, your estimate is going tochange 
enormously, isn't it?That second piece of information, the kind of animal 
my pet is,is far more useful than the first piece, how long it has 
alreadylived. In the same way, if we really want to know how long thehuman 
race is likely to survive, understanding what kind ofbeast we are will be 
far more useful that simply counting up thenumber of years we have been 
around.
--posted by John B

6. July 17th, 2007 1:31 amInteresting idea. I will have to give it more 
thought. Someoneonce told me the following Bayesian riddle:Richard holds 
up two envelopes and tells Mary that one of themcontains twice as much 
money as the other one. He tells Marythat she can pick one, look inside 
and then decide if she wantsto switch. She gets to keep the money inside 
the one shechooses. She can only switch once.Mary picks one but before she 
opens it, Richard stops her andtells her that she should consider 
switching already. Hisargument goes as follows:"There is clearly a 50% 
chance that you have chosen the one withmore money. Lets say that there is 
X dollars in the one youpicked. If the other one has more money, it 
contains 2X dollarsand if it has less it contains X/2. So on average, the 
other onecontains 0.50 (2X) + 0.50 (X/2)= 1.25 X. Therefore it 
doesn'tmatter if you look, your're better off switching for any valueof 
X."Do you really think that she should swicth regardless of howmuch she 
finds?Where is the flaw in that argument? Think about it beforereading my 
answer which I will post later on.
--posted by David Johnston

7. July 17th, 2007 1:36 amHow did such nuttiness get through?If the likes 
of the NYTimes are going to spread such nonsense,we're doomed.
--posted by Dick Purcell

8. July 17th, 2007 1:53 amOne can make valid "Gott predictions" - 
actually, estimates ofprobability - based on his two assumptions. The easy 
part endsthere.There is a hidden third assumption: selecting a scenario 
whichhas only two options: continue or not.I think Dr. Gott's selection is 
story-telling, because thetableaux I think about have nothing but multiple 
options withcomplex paths.I considered a similar problem, Similar 
Circumstances, in myforthcoming book, ETHICS AS SOCIAL CONSCIENCE. 
Intending tocarry out a moral judgement entails a prediction about 
theproposed act and its eventual consequences. I think we make 
thatprediction by estimating Similar Circumstances, which means 
ourintentions may not be carried out exactly.This brings us to Dr. Gott. 
People reject inexact predictionsand risk, which are implied by the fuzzy 
logic of "similarcircumstances." They just want to know ... Dr. Gott 
relies onthat desire in presenting simple, dyadic situations.In other 
words, "Gott-predictions" may be titillating, but theyare not useful.
--posted by Walter L Battaglia

9. July 17th, 2007 1:59 amActually, now that I've thought about it, the 
comment I leftearlier can be significantly condensed.Instead of looking at 
one civilization and asking how long itmight last, suppose you asked a 
different question: Suppose youasked "how long, on average, do 
civilizations typically last inour universe?" We don't know the answer. It 
might be only 10,000years. But it could just as easily be a billion years. 
And if itis in fact a billion years, what then? Well for one thing, 
everyone of those civilizations, while young, will most likely 
havedoomsayers like Dr. Gott. And every one of those doomsayers willbe 
wrong! :-)
--posted by John B

10. July 17th, 2007 2:31 amIt's about time someone said this. The survival 
of our species(and everyother living creature on this planet) rests in 
ourcapacity to innovate and colonize places outside our solarsystem. It is 
know that the Sun (a yellow star presently in themiddle of its lifespan) 
will eventually run out of Hydrogen gasto fuel itself. Whether we like it 
not we will have to leave ourworld and our immediate planetary 
neighborhood.As any knowledgeable scientist will tell you, when the sun 
runsout of fuel, it will expand to many times its present size andengulf 
the first three planets...which includes earth. Pleasesee link 
below:http://cfa-www.harvard.edu/supernova//newdata/supernova e.htmlThis 
is the destiny of our civilization. Either learn to livebeyond the 
confines of our planet (and its neighbors) or perish.This is not news. It 
is taught in every science class from 5thgrade and forwards. You don't 
need a college education or a PhDto find this out. Just go to your nearest 
planetarium to findout the "inconvenient truth" about the sun. If you are 
boldenough to find and confirm this information...to you I say yougive our 
civilizatio hope. To those who don't "believe" or areunwilling to research 
these facts...well to you I say...well Ireally have nothing to say to you, 
I'm sorry.
--posted by Jose Cordero

11. July 17th, 2007 3:57 amIt seems that this theory's major limitation is 
that mostanalysis takes place from a priviledged standpoint. Usually 
whenyou are trying to evaluate longevity you are doing so 
becauseparticular sets of circumstances have aligned and put you in 
theposition to need to make such a judgement. In other words if youare 
trying to figure out how long something might last you areprobably doing 
so because you have outside knowledge and it isthat outside knowledge that 
is begging the question. In the caseof a fight in a relationship if you 
are evaluating whether ornot the relationship will last and it is probably 
because youhave noted an increase in tensions over time. If you are 
tryingto figure out how much longer a show will last it is usuallybecause 
of its continued or declining revenues. In the case ofthe life of the 
space program or even modern civilization itselfthere are many factors 
that beg the question of longevity --slowing public interest in space 
travel, continued nuclearproliferation, popluation density increases, 
global warming,increased religious fundamentalism in most regions of the 
worldetc. and it is this specific moment history - a 
privilegedunCopernican one - that makes us wonder whether we'll be 
aroundmuch longer. Since it is specific factors that create 
questionperhaps it is these factors that will lead us to a more 
accurateconclusion.
--posted by Joel Schectman

12. July 17th, 2007 5:12 amThe theory that provokes this discussion is, in 
my opinion,selective dissembling. I have found the responses far 
moreinteresting and informative than the subject.Most credible scientist 
agree that all higher forms of life,mammals and such, will be unable to 
exist on planet Earth inanother 500 million years or so. Furthermore, the 
universe as weknow it today, will proobably cease to exist and will 
eventuallybe unable to support life. So humans might be better to 
accepttheir future non-existence.I thought a recent opinion by Stanley 
Fish about summed it allup for me. It started:"Literary history is full of 
stories of men and women whose oncerising stars fell below the horizon, 
but who were rediscoveredand even canonized (in the literary sense) after 
they died. Whatmust that feel like?Unless you believe that not only is 
there life after death butalso that in the other life you will be able to 
keep tabs onthis one, it doesn't feel like anything. It certainly 
doesn'tfeel like success, even in prospect. No one opts for 
the"undervalued when alive, but admired when deceased" track. Thepleasures 
of being vindicated in the long run are experienced bythose left behind, 
by biographers and torch bearers; it is theircareers that flourish. How 
can that be satisfying?"
--posted by Bill Baker

13. July 17th, 2007 8:44 amThe assumption is that this moment (or most 
any, for thatmatter) is not exceptional and can thus be reasoned 
from.However, doesn't the proliferation of nuclear weaponry and thegrave 
threat it represents make this, in historical terms and asa practical 
matter, a most distinctive moment in human history?It seems to me 
analogous to predicting the future longevity of amarriage while angry 
spouses were training guns at each other.
--posted by Jeff Waingrow

14. July 17th, 2007 8:46 amAll this philosophy is truly insignificant. We 
are not merelyinformed about the issue beyond Gott's assumptions, we 
havedetailed information and common sense on top of it. Yes, it'strue the 
American people are losing interest in NASA mannedspace exploration, but 
they're also gaining interest inentrepreneurial space ventures, and there 
are new countriespursuing manned spaceflight.There are huge aerospace 
business interests invested in keepingspaceflight alive; a huge amount of 
private support fromenthusiasts who are inspired by it; and the militaries 
of dozensof countries depend on it. Furthermore, Russia is 
realizingmassive profit potential selling tourist tickets on Soyuz, notto 
mention the talk of circumlunar tourist flights for $100 mil.There are 
billionaires, hundred-millionaires, and all otherlevels of entrepreneurial 
wealth invested in making space cheap,reliable, and available to the 
general consumer, and several ofthese companies make more progress toward 
that goal every day.Hardheaded businessmen are beginning to think it's 
plausiblethat private ventures will land people on the Moon before 
NASAreturns there. And once there are people living out 
thereself-sufficiently, there's no reason they would close up shopand come 
back. In fact, they would just spread farther.As to the Fermi paradox, 
even the thought that we could imaginewhat a galactic civilization would 
look like or entail ispreposterous. The likelihood that there aren't 
organic creatureswhizzing around the galaxy in recognizable spaceships is 
asobvious as there not being amoebas driving SUVs down thefreeway. That 
has absolutely nothing to do with whether beingsonce like us can keep on 
progressing, evolving, and spreadingindefinitely. But we can safely say 
that people as we knowourselves do have the potential to colonize the 
solar system,and where we go from there will be arbitrary. A single 
large,hollowed-out asteroid could have more living space than planetEarth, 
so you could take it wherever you want, for whateverreason suits 
you-planets need not apply. Now imagine billions ofsuch asteroids, each 
with more people in them than now live onEarth, and each going off 
wherever or staying put as its peoplechoose. Mankind's future is bigger 
than we can possibly imagine,if we can just avoid disaster for a few more 
decades.
--posted by Trent Calabrese

15. July 17th, 2007 8:50 amGott's work is of interest but be aware that 
much spacecommunity work is now progressing rapidly on realistic 
timeframes of coming decades.I can't predict precisely when humans can opt 
to live in a spacecommunity. To determine when it will be, however, is not 
a Gottprediction as much as an assessment of when market forces 
andpolitical desire, as well as our human drive, will make ithappen.Tom 
DiffenbachSpace Social Political Projectdiffenbach at comcast.net
--posted by Tom Diffenbach

16. July 17th, 2007 9:12 amThe threats to the survival of our 
species/biosphere are far farfar more immediate than the expiration of our 
Sun! LOLIf our descendants are still extant at that remote future I 
daresay they will be to us what we are to frogs and will have longago 
spread their bi-technical-cultural "DNA" beyong this solarsystem.Now, 
getting back to the present day "real time" threats.I say the most 
immediate threat to our survival is a globalsystem of competing 
nationalism/sectarianism in which peopledefine their sense of identity by 
the accident of where theyhappen to be born and the conditions of their 
particularcultural environment.The cumulative consequences of competing 
pathological cancerous"growth" in all manner of arenas (climate change, 
bio-trrorism,nuclear war, etc) are concrete threats to 
humanexistence/civilization.Oh, and it would be a good idea to invest the 
36 billion buckswe're slated to spend in Iraq over the next three months 
in aprogram to track and divert any asteroids/objects that mayimpact our 
lovely home. What a cheap insurance policy THAT wouldbe? Eh?Meanwhile, the 
insanity continues. If it weren't such an ongoingtragedy; it could be a 
Keystone cops Comedy.Having said all that, I remain optimistic/hopeful.
--posted by Nick Lento

17. July 17th, 2007 9:43 amThis kind of predicting is fun- but not as 
useful as we hope itwill be.It's that darned remaining 5%. It's a real 
chance you're wrong-in which case all your decisions based on the 95% have 
beenwasted.Personal experience here. Neither my wife nor I had 
anypredictors for Type 1 diabetes. But. Our son developed it whenhe was 8 
years old. No warnings. And the chances for him; givenus as parents, were 
1 in 20,000, we were told. Quite a lot lessthan 1 in 20.But for him- his 
reality is- 100%, diabetes. Those lovelycalculations of chances can be 
irrelevant.In the case of the survival of humanity- it might be best to 
doSOME preparation for ALL chances. Just in case. And don't puttoo much 
faith in the big prediction. In the real world-sometimes- 95% is still- 
wrong.
--posted by Philip

18. July 17th, 2007 10:12 amThis is an absurd notion. We may never 
colonize Mars. We mayhave an outpost on Mars in this century, but it will 
likely beinhabited by only a small number of people, i.e. 
engineers,scientists and technicians. There is simply no reason to 
leaveour planet. If the thinking is that we will over-populate anddeplete 
the finite supply of resources, the thinking discountsthe power of disease 
to deplete the population as well as thepower of climate change that has 
so altered life-form on theearth throughout its geologic history. In fact, 
humans willlikely become extinct in a million years or so.
--posted by Paulboy

19. July 17th, 2007 10:19 amComment #2, regarding the 95% certainty 
level.There are real problems with that whole concept- with real data;from 
this world. A study published in JAMA about 2 years agofound that more 
than 30% of medical research was later found tobe "exaggerated, or totally 
contradicted" by later 
research.http://www.theregister.co.uk/2005/07/14/medical_studies 
_wrong/Think about that- very hard. The medical research community hasvery 
high ethics standards, and better ethical oversight(usually) than other 
branches of science. They do the best theycan.EVERY ONE of those 
overturned studies met the 95% certaintycriterion. And every one withstood 
"peer review".And more than 30% turned out to be wrong. The actual 
predictionwould be that only 5% should have turned out wrong.That is hard 
evidence that there is something very dicey aboutthe whole 95% certainty 
schtick. It does not work- as applied byhumans, today.Not something I'd 
like to bet my survival on.
--posted by Philip

20. July 17th, 2007 10:20 amThe problem with this predictive method isn't 
that it'sinaccurate or flawed, simply that it doesn't say much. I've 
beendating my present girlfriend for 4 months, and this methodasserts, 
with 95% confidence, that we will break up between 3days and thirteen 
years from today. I have no doubt that its astatistically sound 
prediction, but its not a particularlyenlightening piece of information, 
especially given that itsexpected to be wrong one time in twenty.
--posted by Tyler Hoppenfeld

21. July 17th, 2007 11:15 amInstead of Copernican Principle, could it also 
be calledLaplacian Principle, based on his Law of Succession? Or 
perhapsBayesian? Or Saunderson?
--posted by Terry Ireland

22. July 17th, 2007 11:46 amThe absurdity of Gott's method becomes clear 
if you change thetime scale -- say, weeks to microseconds. I have survived 
thelast 39 microseconds so there is a 95% chance I won't survivepast 1.521 
seconds?
--posted by Steve Myers

23. July 17th, 2007 12:00 pmWe have been in the current period of global 
warming between10,000 and 15,000 years (since the last ice age began to 
melt)let's call it 12,500 years... Based on Dr. Gott's method we 
willcontinue in global warming for a minimum of 12,500 years moreand a 
maximum of 20,000,000 years...
--posted by Dennis O'Connor

24. July 17th, 2007 12:02 pmI agree with John B's comments about the 
shortcomings of thismethod of prediction. This bootstrapping method of 
predictingmay be of some value, but really only if we contextualize itwith 
other known data. If Dr. Gott's methodolgy were appliedduring the second 
year of the space program, then it would behighly unlikely we'd have made 
it to the moon in 1969. In a moresignificant topic, how do we know whether 
homosapiens 200,000years of existence is the equivalent of the second year 
of spaceprogram, or for that matter, an extremely long time for aspecies 
to thrive? Perhaps in other life sustaining planetsviruses, natural 
disasters, etc routinely wipe out species, whoknows? We don't have data 
about any other form of life exceptfor us and other animals on our planet. 
Without some othercontext data, applying this formula to "predict" man's 
likelyplanetary era would seem to be a useless stab in the dark.
--posted by Jerry

25. July 17th, 2007 12:11 pm"And/or irresponsible leaders could start a 
doomsday war onEarth, and then flee with their families and their 
equallyguilty advisors & ideologues for a safe colony, without facingthe 
repercussions of their malign management."I have a better idea. Lets send 
George and Dick to Mars nowbefore they have a chance to destroy the earth.
--posted by Jared

26. July 17th, 2007 12:23 pmDr. Gott's "Copernican" method of forecasting 
future eventssounds suspiciously like Andy Kessler's description of how 
hedgefund managers operate, i.e., first you pretend that you 
knowabsolutely nothing about a certain set of circumstances, andthen based 
upon that mental tableau rasa, you try to figure outwhat you "know" about 
that same situation that nobody else does."Forever looking for the other 
side of the trade," was howKessler summed it up, and it sounds a lot like 
the Gotttechnique.When it comes to really critical questions like 
thesurvivability of the human race and how seizing on 
aonce-in-a-species-lifetime historical "window" for spacecolonization fits 
into achieving that noble goal, I prefer theinformed thinking contained in 
this 2000 presentation by Prof. Joseph N. Pelton entitled "The Next 
Billion Years and theSignificance of the Emerging Global Brain," delivered 
as part ofthe Arthur C. Clarke Foundation lecture 
series:http://www.clarkefoundation.org/archives/2000.php
--posted by Joel Rennie

27. July 17th, 2007 12:42 pmLet's try this analogy:When were boats 
available to colonize the Americas? At least bycirca 1000 AD when the 
Vikings had colonized Greenland andNewFoundland. Yet when did sustainable 
colonization begin? Notfor another 500 years.What was the Copernican 
probability of that at 1000 AD? Clearly,there are cases where the slice of 
time in which you make aprediction is rather important and, as mentioned 
in othercomments, 5% is still a real, albeit, slim chance.Even though the 
technology is available to colonize the moon andMars (maybe a stretch), 
could it be that humanity is 500 yearsoff from making it happen? Of 
course, Europe suffered somesignificant setbacks between 1000 and 1492, 
such as the Mongolinvasions and the Black Death...
--posted by Brian

28. July 17th, 2007 1:04 pmNo point in colonizing another planet if 
religionists settlethere.If all the religions that exist here expand 
theirhate-filled superstitions into outer space, humans will justrepeat 
the endless carnage that we have had here for mellennia.
--posted by maddy wong

29. July 17th, 2007 1:19 pmOnce again, the space is filled with another 
week's ration oftwaddle and blather.
--posted by arty

30. July 17th, 2007 1:27 pmDon't know about `religionists' settling 
Mars-am sure they'd berepresented-but check out the old Arni movie, "Total 
Recall"(1990). Silly as it sounds, this picture of Mars colonizationis, 
unfortunately for us, all too familiar.
--posted by David

31. July 17th, 2007 1:28 pmContradicting Gott, we do live in exceptional 
times. For only ablip in time, we have enjoyed and will soon run out of 
cheapoil. Our planet's very ability to support over 6 billion humansis 
predicated on massive expenditures of cheap oil. Many havepredicted we 
have already reached peak production, and on thedownhill slope is 
instability, famine, war, disease and the endof economic progress. The 
space program itself relies heavily oncheap oil as does every other 
industrial endeavour.Humans may continue in some form of civilisation 
after thecoming dark times, but it might already be too late 
forcolonisation.I hold no hope for colonisation anyway. We were blessed 
toevolove on this wonderfully life sustaining planet and we havevirtually 
killed it with little understanding of our ongoingfailure to manage this 
gift. How could we manage to survive onMars' harsh and unsustaining 
environment. Just look to thefailure of the Biosphere project. People who 
should have knownbetter tried to squeeze too many humans, poultry and game 
ontotoo few acres of land. Of course the system was overwhelmed bywaste 
since there were not enough insects and microbial life tohandle the top 
heavy model. To envision even a modest outpostway off on Mars would be to 
demand regular support missions fromearth for basic provisions. We will 
very soon be unable toafford such missions as more pressing matters of 
allocatingscarce resources will be in the hands of a powerful few.
--posted by James Farrell

32. July 17th, 2007 1:35 pmOne thing I don't understand about this 
theory... is its abilityto predict endings through time. As an even 
continues, itsending should be postponed further and further...In the case 
of the poker player with the lucky streak...shouldn't she become 
emboldened as she continues to win?
--posted by Farrah Zughni

33. July 17th, 2007 1:35 pmIsn't this about how we choose to define what 
we are looking at?Sure the space program is only x years old, but what if 
that isthe wrong thing to measure? Human exploration of other placeshas 
been fairly constant couldn't our timeframe begin with thefirst human, or 
at least the first human found in north Africaor Europe or Asia. Or 
couldn't it be the invention of the wheel,or the use of something other 
than feet for transportation?ANyway, humanity will end eventually, or not, 
but probably.
--posted by Brian

34. July 17th, 2007 1:41 pmIn the begining- there was "hard" Science 
Fiction. Writers madean effort to use real facts, and extrapolate from 
there. Ifyou've looked at what is called sci-fi these days, it's 
mostlygone soft. Let's not get into that.The point is: a lot of good 
brains spent a lot of years actuallytrying to think about the physics of a 
future in space. Whywould we just start over, from scratch? A huge amount 
of realwork has been done here.One major suggestion from those thinkers: 
having once escapedgravity- why would you go back? Why colonize Mars- when 
youcould just as easily- in fact much MORE easily- colonize theasteroids? 
Neither Mars nor asteroids have useful atmosphere;you're going to have to 
live in pressurized, heated containers.In space- you have access to 
essentially endless solar power-the naked sun. One of the more interesting 
ideas- set up bigmylar mirrors- focus them on a big mostly iron asteroid- 
andspin the asteroid. Heat it to nearly liquid. Not hot enough? Adda 
mirror. You should be able to blow a big iron bubble- whichyou could then 
keep spinning; for internal gravity- let it cooland solidify; and then 
live on the inside of. You can usemirrors to smelt metals this way, 
too.Far out? Possibly less far out than trying to keep a supplytrain open 
using chemical rockets. There's water, methane,metals, oxygen- anything 
you need in the asteroids. You couldalso build great big nuclear power 
plants- and never worry aboutpollution- there's nothing to pollute.Another 
weakness of "strong predictions". What if you've askedthe wrong question?
--posted by Paul

35. July 17th, 2007 1:41 pmI think that all this space flight talk is too 
fancyful. Haveyou seen how much energy it takes to launch 
spaceshuttlecontaining just a few astronauts? Do we even have enough 
energyto launch sufficient numbers of humans and supportinginfrastructure 
to colonize another planet? It is not practicalwith the technology we 
have.We better shape up and take good care of mother planet earthbecause 
this is the only practical residence our species has. Itis good to dream 
but wise to be practical and make do with whatwe have.
--posted by sanjay

36. July 17th, 2007 1:46 pmAt the rate the human race is using up its 
natural resources, wewill be lucky to last 100 years without a major 
collapse of mostcivilizations on this planet. The first world alone 
already usesmore than the planet can sustain. If the rest of the world 
wereliving with our rate of consumption, society would already havefailed.
--posted by Michael Justin

37. July 17th, 2007 2:05 pmIt seems to me that the primary shortcoming of 
the "Copernicanprinciple" is that it can really only predict 
cumulativeoutcomes, not individual ones. The fact that Gott was around 
95%accurate in his predictions regarding the longevity of some 300leaders 
says nothing whatsoever about his accuracy in predictingany given one. It 
seems to me that this prinicple is aninteresting statistical observation, 
but of very little actualutility, at least as Gott is applying it.
--posted by Steve

38. July 17th, 2007 2:05 pmThe big soft spot in this story, and in Dr. 
Gott's formula, isthe "says he hasn't seen the formula fail yet" part. 
Thisanecdotal comment suggests that the formula has not beenrigorously 
tested. There seems to be considerable room for theoperation of 
confirmation bias-i.e., Dr. Gott applies hisformula in situations where it 
is likely to produce an accurateprediction, and doesn't apply the formula 
when it is unlikely tobe accurate. The variety of potential applications 
and the mushydiscussion of them suggests that there are no objective 
criteriafor determining when and where the formula is likely to have 
ameaningful application. In the absence of testing,falsifiability, and 
objective criteria for evaluating validity,this isn't science-it's just 
fun with numbers.
--posted by Robert Radcliffe

39. July 17th, 2007 2:09 pmI know nothing more about Gott's method than 
what's in thisNYtimes article, but it seems extremely simple-minded and 
Isuspect it would only be intended for use as a low qualitytechnique of 
last resort (if it were intended for any seriouspurpose).On the other 
hand, what this technique is probably intended foris to build careers with 
a minimum of effort, specificallyGott's. This has been an increasingly 
common phenomenon inscience over the past 20 years (thanks baby boomers). 
And, sincewe are here in the NYtimes discussing it, it has evidentlyworked 
in this case.The Times tells us the support for this technique comes 
frompredicting the careers of politicians, but all that suggests tome is 
that human lives are very easy to predict. Yes, that'sright, we are all 
not as unique and different from one anotheras Hollywood movies like to 
suggest. But you can't justextrapolate this technique from that to the 
probable duration ofthe only known intelligent civilization in the 
universe. First,you need to show much more convincing and specific data to 
provethat this technique links in with some deeper functionality 
ofphysical law. Good luck with that.
--posted by Steve in L.A.

40. July 17th, 2007 2:19 pmGott's method is accurate (of course) but 
preposterouslyuseless. The more information you have about a particular 
eventor thing, the more likely you will be able to predict 
somethingrelating to that event or thing in the future. For instance,using 
Gott's method, there is a 95% he will be accurate ifpredicting for the 
world of "all items," including bacteria,fungi, tortoises, etc.But, once 
you know the item in question (whether it's a bacteriaor a tortoise) and 
some piece of information relating to thatitem (for instance, how long a 
tortoise lives, on average),predicting based on lesser information (that 
the item exists) isirrelevant and misleading. Knowing we are humans, 
knowing all ofthe events befalling us (some of our own making), knowing 
thestate of the world (and the specific science behind certainthings that 
are happening in the world) would make a much moreaccurate prediction of 
how long we will be around than somegeneralized predictive formula applied 
to the universe of allobjects.Finally, and not to be too disparaging, but 
nothing in sciencehas been accomplished by finding 95% confidence 
intervals.
--posted by Steve

41. July 17th, 2007 2:28 pmOne other thing I wanted to say on this topic. 
Gott is fallinginto the scary trap that the most careerist scientists 
havetaken to increasingly over the past 40 years, the trap of 
makingpredictions (especially bold, sensational predictions). This 
isdangerous because 5 centuries of science have shown it is anexcellent 
tool for the empirical realm and a weak tool for thetheoretical or 
predictive realm (not that there are better ones- the message should 
probably be "stay away from too muchprediction").When earlier humans saw 
some yellow substance oozing out of theground, science was the tool for 
identifying it. Go off andspend months or decades doing exhaustive 
empirical testing, andeventually science tells you what that stuff was and 
what it'sgood for.But ask how long the sun will burn in the sky or whether 
fasterthan sound travel will eventually be possible (just before 
ithappened), or what the nature of a black hole may be (withHawking's work 
now famously proven wrong), or how the dinosaurswent extinct, and what you 
get as an answer from any scientistshould be taken with a huge grain of 
salt. It is hubris to makeany such predictions, career-building hubris, 
nothing more. Waitand watch as these bold predictions come unraveled over 
the nextfew centuries. Even Einstein's work, much of it, remains farfrom 
proven, and the Times should be doing a better jobreminding people of that 
fact.We live in gullible times, and one reason the space race mayhave 
slowed is that the payoff for bullshit even in thescientific world has 
recently become larger than the payoff fromreal hard work.
--posted by Steve in L.A.

42. July 17th, 2007 2:29 pmBiosphere 2
>       From Wikipedia, the free encyclopediaOn June 26, 2007, the 
University of Arizona announced it wouldbe taking over research at the 
Biosphere 2. The announcementends immediate fears that the famous glass 
terrarium will bebulldozed. University officials said private gifts and 
grantswill enable them to cover research and operating costs for 
threeyears with the possibility of extending that funding for 10years.I'm 
reminded of the quote of w. Clement Stone. "Whatever themind of man can 
conceive and believe, it can achieve."So with a guarentee of 3 years and a 
possiblity of 10 more yearsand it's current life span staarting at 1985 
anyone want to makea prediction?
--posted by Donna Ruark

43. July 17th, 2007 2:29 pmIf the human species can't survive on earth, 
what makes us thinkit ought to survive somewhere else? We may very well be 
anevolutionary dead end, despite our great self-absorption.
--posted by Sylvia

44. July 17th, 2007 2:34 pmI'm not using Dr. Gott's formula, but I've done 
my own share offorecasting about the future of the human race in a tried 
andtrue tradition: literature. Following Huxley and Orwell-and afew pop 
influences along side-I calculate that the fall ofhumanity will come in 
2050. Read about our future history in myrecently published dystopian 
novel (ebook) 2050: Gods of LittleEarth. www.speculativefictionreview. 
Climate break-down,technological catastrophe and chronic warfare-along 
with a lackof food and water-will plague us to a disastrous degree in 
thecoming decades. Depressed yet? Wait until you see who follows inour 
foot steps!
--posted by J. Zornado

45. July 17th, 2007 2:45 pmJoel Rennie's link to the Clarke Foundation 
lecture(http://www.clarkefoundation.org/archives/2000.php) clearly makea 
wonderfully detailed technological/philosophicalcase/projection into a 
future in which humanity not onlysurvives, but thrives.......and 
evolves!!! (I dare say thatwhatever unfolds, if our species continues to 
exist/evolve formillennia will make the projections at that site seem pale 
incomparison!)It occurs to me that something as seemingly mundane and 
"local"as America changing our campaign finance laws so that they areALL 
publicly financed just might be the beginning of asurvivable future for 
our nation and our species.The corporate/nationalistic/sectarian/political 
status quo isall tied up in sheer greed/egoism/ and power lust geared 
towardsatisfying the short term needs of the most pathologicallyruthless 
amongst us.For such maleficent creatures "the future" is a 
meaninglessconstruct unless they are in it and "in control" of it. 
Suchpeople misconstrue the "survival of the fittest" cliche so thatit 
justifies total selfishness at any cost. That "consciousness"translates 
into, again, a certain and deserved speciesextinction.Raising the 
consciousness of the American people to the pointwhere so many of them 
actually saw clearly that our extantcampaign finance system guarantees 
legalized bribery/corruptionas the core reality of our governance is a 
good part of what itwill take to force our "leaders" to do what is 
right.99% of our problems stem from our own very "nature" as humanbeings. 
All the techno-biological fixes are out there inClarke's projections; but 
if we don't evolve at the level of acommon human sense of global 
decency...extinction is 100%assured (and deserved).America has this 
wonderful altruistic/idealisticConstitution.......if we can actually BE 
the worlds leader inREAL freedom and human rights and economic justice, it 
justmight be the key to the future of our species!As things are 
now...America has become a source of thecultural/economic malignancy that 
afflicts the human race, wecan turn it around. We must.It's not a 
Pollyannish fantasy to assert that love/altruism isabout understanding 
that we share a common human spirit thattranscends linear time/space.As a 
wise man once said, "Spirituality is, above all,practical"!
--posted by Nick Lento

46. July 17th, 2007 2:51 pmAnd what about the aliens that already live 
among us? Will theysimply return to their home planets?!
--posted by Pablo

47. July 17th, 2007 3:12 pmMy online essay, `Nonrenewable Resources and 
Spacefaring: AFuture History?' bears on John Tierney's article, 
andextrapolates from prevailing realities. The problem is asuniversal to 
us all as are the effects of `climate change.' Myonline posting is `public 
domain' and may be freely downloadedat: 
http://hometown.aol.com/yarnspinner88/myhomepage/politics.htmlExcerpt: 
During the First Decade of the Twenty-First Century(Common Era Year 
2007):- a convergent focus is intensifying by the world's 
governments,private sectors, media, scientific, academic and 
otherinstitutions, and humankind generally on:1. the Earth's steadily 
diminishing reserves of accessiblenonrenewable metals, minerals, and other 
natural sources fornonrenewable substances essential to sustain 
civilization'sindustrial base into the future;2. initiatives and 
commitments throughout the world towardcreating the means by which 
humankind will transform intorealities its vision of evolving into a 
spacefaring race;3. rapid progress in developing technological and 
logistics'capabilities to explore, locate, identify and acquire 
essentialindustrial-base prime and alternate substances fromever-deepening 
wells in the Earth's crust and confident, intime, from elsewhere 
throughout the Solar System and beyond.4. rising expectations in Global 
Exploration Strategies forhumankind's eventual transformation into a 
universal venture byhumankind generally.Meyer Moldeven
--posted by Meyer Moldeven

48. July 17th, 2007 3:17 pmSystemic entropy,Closed systems will collapse 
from increasing complexity unlesssupported from outside the system. To 
open the system willrequire effort in a single or very few directions to 
assuremomentum continues growth.Mankind squanders its momentum in wasted 
efforts that yeildnothing but increased complexity. On this, judgement 
appearsmisapplied to determine the WHEN.
--posted by Salan

49. July 17th, 2007 3:32 pmTwaddle and blather indeed.A geyser has a clear 
beginning. So does a political tenure. ButHumanity? The `beginning' of a 
species? That's an arbitrarypoint in a nonlinear progression.Observing the 
same principle across species, it is then far morelikely the we evolve 
into something else before something "getsus".This is a crisis of our 
collective ego, and nothing more.
--posted by Mike

50. July 17th, 2007 3:39 pmHere is another indication that something is 
badly wrong withGott's argument.Let's say I happen upon some phenomenon 
that has already lastedfor a week. According to Gott, I can use this 
information tomake a useful prediction about how much long the phenomenon 
willcontinue.Then I notice Fred W, who has been sitting next the 
phenomenonfrom the moment it started. For Fred, Gott's argument is 
utterlyuseless. Even Gott has acknowledged that his method isinappropriate 
for some situations. For example, he admits thatyou can't predict, one 
minute into a marriage that, that themarriage will probably last no longer 
than 39 minutes. Hisexplanation is that this is because you have been 
invited to thewedding, and therefore are not observing it at a random 
momentin time.So what about Fred? Since he has been observing from 
thebeginning, he is NEVER going to observe the phenomenon at arandom 
moment in time, no matter how long he sits there. Fred iseither going to 
have to predict a 39 second duration after 1second, then a 39 minute 
duration after 1 minute, and so on, orelse he is going to be forced to 
admit the obvious, which isthat he can make no prediction at all.So think 
about it. One week into the phenomenon, according toGott, I can make a 
prediction about how long the phenomenon isgoing to last, but Fred, who is 
sitting right next to me, andwho knows nothing more or less than I know, 
cannot. Come on!Isn't there something obviously bogus here?
--posted by John B

51. July 17th, 2007 3:51 pmAshes to ashes, dust to dust.Whenever, there's 
no rush.
--posted by Mort

52. July 17th, 2007 3:55 pmColonizing Mars-or any other planet for that 
matter-if humanitysucceeds in doing so-would make no consequential or 
meanintfuldifference as far as planet earth's human beings are 
concernedbecause one earth day into the future the sun's store ofhydrogen 
and helium will run out for sure; our sun will turninto a black hole, 
sucking into it all the planets and otherobjects orbiting it. Nothing on 
planet earth, no fauna or flora,will survive.That is a certainty governed 
by an immutable Natural Law of thevisible Universe.Solar systems are born 
out of cosmic dust routinely andregularly all throughout the visible 
universe-and with them theplanets that are formed out of their debris. 
They then gothrough a cycle of (from birth) adolescence, growth, 
maturity,senesence, and-inevitably-death.Not only solar systems are 
subject to this immutable cycledictated by a Natural Law of the visible 
Universe. Galaxies andclusters of galaxies are themselves inescapably 
subject to it.But the Universe goes on replicating and multiplying 
itself-onand on-forever.
--posted by Mar Patalinjug

53. July 17th, 2007 4:02 pmJohn...Richard Gott should lunch with Sir 
Martin Rees and WHAT aconversation that would be! We did a similar post 
"Dr StangeloveTwo? -Cambridge Physicists Gives Earthlings a 50/50 Chance 
ofSurviving the Century." Includes a great video of Rees on thesubject @ 
www.dailygalaxy.com
--posted by Casey Kazan

54. July 17th, 2007 4:02 pmthe question, as phrased asked about humanity 
being dead.humanity is dead. such is to be distinguished from human life.
--posted by steve

55. July 17th, 2007 4:03 pmThis dovetails with something that I argue with 
"ecologists"about.The thought that we may have a time in which to do 
somethingthat is not a restriction -- such as conservation or 
analternative (produces less CO2, but puts out the same power),but a 
breakthrough.Michio Kaku categorized civilizations in the amount of 
availableenergy. A Type 0, has the power of a planet. A Type I, 
astar...then a galaxy, and so on...civilizations move up, orstagnate.My 
corollary to this thinking is that we cannot pussyfoot aroundwhen it comes 
to getting to the next level. Look at life. Thingsgrow, mate and die. The 
mating time is short compared to therest of the lifespan. It's sink or 
swim. That's where we're atnow. Worrying about how much oil there is in 
the ground is likeworrying about having the right color condom on your 
date. Atsome point, either something magic happens and it just 
doesn'tmatter -- or you go home with an unopened rubber.That's where we 
are at now...I think we have to burn every scrapof wood, coal, oil and 
uranium to get us to a Type I. That maymean going to Mars, and giving the 
scientists the last drivablecars hoping they'll invent fusion. There's no 
going back -- thealternative is becoming a planetary spinster...destined 
to watchthe sun dwindle out in long, boring millenniums...
--posted by John Bailo

56. July 17th, 2007 4:05 pmAnybody but me notice that an astrophysicist is 
using this(really simple) argument to advance the cause for more 
spaceexploration (and at the same time making a nice little careerwrinkle 
out of it)? Problem with striving to colonize Mars basedon Copernican 
principle estimates is that this is a situationwith lots of additional 
information. Namely:-Mars (or any other planet) cannot possibly be made 
inhabitablefor humans through an application of technology and 
politicalwill without first developing the technology and political 
willrequired to fix our own, much more human-suitable planet. (Andthe 
clock is ticking.)-Assuming we can fix our planet (and retrofit Mars) 
we're stillultimately done for unless we can figure out a way to 
travelbeyond our solar system.The first point is the most important. 
Anyone read the articleabout the lack of funding in solar cells? In that 
context, anyMoon-Mars talk is lunacy.
--posted by David Mebane

57. July 17th, 2007 4:19 pmthe copernican formula seems perfectly rational 
and plentyuseful in the absence of other info.of course, in this case, we 
have had other info for decades. weknow the following: there are scarce 
resources on the planet,and as the population of the earth increases these 
resourceswill decreasingly be able to support that population. 
regardingthe "new" conclusion that Gott has proffered, we can nowrephrase 
that statement. as the earth becomes increasinglyovertaxed by population 
pressures, the probability that man willutilize the increasingly scarce 
resources to find new resourcesbefore that becomes impossible can, with 
reasonable probability,be estimated as 50/50.unless we, the current 
population of the world, take action andmake plans to do something about 
it by choosing to expand intoand to colonize space, our chance of killing 
humanity - becausewe are probably the generation most able to affect the 
future ofmankind - is equal to a coin flip.of course, if the democrats win 
the upcoming election, thechances are probably closer to 95% certain.
--posted by michael

58. July 17th, 2007 4:24 pmA system of prediction with a built in 95% 
success rate seemslike a prophets dream!Of course, it is rigged, by 
predicting such a huge span of time(95% of the pre-existing time) that it 
often works.The prediction that the human race will lastbetween 5100 and 
7.8 million more years is not very useful.Imagine using this to budget 
your life's savings for retirement- suing the same type of range - my 
money will last between oneweek and 29 years! Boy, don't I feel secure 
now.This is a built in slop of 95% of some whole amount. That's 
notscience.Hey, used car salesmen could really use this method - "Hey, 
kid,look, it lasted 20 years already, the Copernican Principle saysthat 
it'll outlast any new car just off the assembly line!"A neat philosophical 
and statistical trick - but just that.Kip Hansen"Fact checking makes the 
world a better place."
--posted by Kip Hansen

59. July 17th, 2007 4:38 pmThere is one thing that is not explained, which 
should be noted.Why 40? It's actually pretty simple.The process lasts a 
time Ttot = Tpast + TfutureIf you assume now isn't special then r1 = 
Tpast/Ttotal israndomly distributed between 0 and 1.If we want to choose a 
range that Tfuture falls within 95% ofthe time (and we want to split our 
inaccuracy equally over tooshort and too long), then we pick a range where 
r1 is anywherefrom 0.025 to 0.975. This is because on;y 5% of the time 
will werandomly have had a past that is less than 2.5% of the range ormore 
than 97.5% of the range.Since 1/0.025 = 40 that's where the 40 comes from. 
The number 40isn't special, but simply a result of the confidence 
intervalchosen. For a 99% confidence interval it would be 200, for a 
90%confidence interval it would be 20.I like it. Clever yet very stupid.
--posted by Mark Schroeder

60. July 17th, 2007 5:07 pmAs for learning the past and applying it to the 
future -We will need to have exactly one colony on Mars. If we have 
two,eventually, at some point, they will start a war.
--posted by Kal

61. July 17th, 2007 5:14 pmSalan- "Mankind squanders its momentum in 
wasted efforts thatyield nothing but increased complexity. "A painful 
truth. It has been my own fantasy for years that THISis the reason no 
aliens have ever contacted us: just at thepoint where the complexity of 
any civilization allows them toget into space- the need for cross checks 
and verificationsbecomes overwhelming. Like Douglas Adams' "shoe event 
horizon",all civilizations at this stage reach a "paperwork eventhorizon", 
where it becomes impossible to do anything but filenotices of proof that 
you have filed the appropriate notices...regarding those notices that you 
are required to file...Are we there yet? (I still fantasize about writing 
that storysome day...)
--posted by Philip Rutter

62. July 17th, 2007 5:33 pmHumans or their successors really should get 
out of the solarsystem before the Sun explodes a few billion years from 
now, andGott's methodology it wouldn't be surprising to have 
anotherdinosaur-killer-sized event happen within the next 65 millionyears 
or so, so we probably should hurry up and get seriousabout getting off the 
planet within the next couple of millionyears.But if we're going to 
colonize other planets or nearby space, weneed more than just rockets - 
we'll need to know how to runplanet-sized ecosystems and long-term 
closed-ship ecosystems.It's going to take a long time to learn that, and 
to develop thescience and engineering that'll make solar system 
colonizationpractical, and we need to avoid becoming dead before we do 
that.So far we've got one planet-sized ecosystem experiment that'sstarting 
to fail badly - we've killed off lots of species on thedry parts, 
seriously trashed the wet parts, measurably changedthe atmosphere, and 
messed around with the thermostat. Theclosed-system experiments have 
mostly been toy terrariums likethe Biosphere, and even it had to cheat 
when the oxygen levelsgot too low, which you can't do in outer space. Even 
theground-supported Space Station has had problems with weirdmolds.There's 
a huge amount of fundamental bioscience that has to bedone before we leave 
the planet, and if we can't clean up afterourselves here, we can't doing 
anything long-term in spaceexcept as Earth-supported tourists. Tourism can 
be fun, and cando a lot of cool science out there, some of which can help 
uslearn what's happening down here and how to manage it better,but the 
only way to save humanity through space travel is tosave humanity by 
fixing the Earth first.
--posted by Bill Stewart

63. July 17th, 2007 5:42 pmSure, for what litle it is worth, I accept that 
there is a smallprobability that we are in the last few percent of our 
tenure asa species.However, that said, the theory does nothing to suggest 
thatchanging planets will change our chances of living longer.Indeed, 
taking the presidential example, all the theory tellsyou is that there is 
a 2.5 percent chance he will be out ofoffice in only x weeks. Let's say 
you want the president to lastlonger than x -- well, the thoery doesn't 
tell you anythingabout that. Maybe (if it's January 19th) you need 
aconsititutional amendment, or maybe not. That kind ofprescription 
requires normal political analysis (e.g., shouldyou come clean about a 
past cover up, or should you cover it upmore, do you have enough time left 
for a consititutionalamendment, or would martial law and a coup work 
better, etc.).Similarly, the theory tells us that there is a small 
probabilitythat we will only last another 5,000 years or so. But the 
theorydoes not tell you anything about whether moving to Mars willhelp -- 
or hurt. Indeed, if climate change is going to make thisplace 
uninhabitable, we should get one the move. But if asupervirus is what is 
going to get us, then all that money putinto space research (and not 
vaccine technology) will actuallybe what kills us. Or vice versa.The 
applicability of the theory is very broad -- but onlybecause it contains 
so little information.In other words, there's no free lunch.
--posted by Chris vLS

64. July 17th, 2007 5:45 pmA quick technical question -- I haven't read 
any of thesepapers, but I'm hoping a mathematician who has can help me 
out.It seems as though this is all based on some kind of 
symmetricprobability distribution, which for something like 
politicalcareers or Broadway shows pretty reasonable. I tend to think 
ofsymmetric distributions arising in situations in which the 
same"dice-roll" is repeated over and over, and for business andpolitical 
careers, that seems pretty alright.But is it reasonable to assume that the 
probability distributionof life-spans for "human races" is similarly 
symmetric? We arepretty clearly exceptional among all species we've ever 
seen onearth. And as technology changes over time, it seems like thenature 
of the game is evolving. So why should we think there isa symmetric 
distribution? Seems to me like the risk ofextinction in any given year was 
high, fell, and then began torise again as we developed nukes.Now, I know 
this is adding other priors, but the assumption of asymmetric distribution 
in the first place is a prior, yes?If anyone has the patience to explain 
these subtleties of thetheory behind these papers to me, I would love an 
explanation.My address is: nickeubank at gmail.comThanks!
--posted by Nick

65. July 17th, 2007 5:46 pmThink of the Copernican Principle as a 
jacknife, that is, asimple, versatile, and generally available tool that 
may beuseful when more specialized tools are unavailable, toodifficult to 
use, or unlikely to be helpful. Jacknives arebetter for opening cans than 
sewing machines, but not for sewingbuttons.
--posted by Mark Menchik

66. July 17th, 2007 6:10 pmAll I could think of while reading this 
articlae was arrows andturtles.
--posted by Zeno

67. July 17th, 2007 6:44 pmIt's hard to believe Gott's argument is still 
around. JohnB hasnailed the basic objection, which was analyzed in 
fullmathematical detail by Carl Caves; 
seehttp://arxiv.org/abs/astro-ph/0001414andhttp://physicsweb.org/articles/news/4/2/6
--posted by Mark Srednicki

68. July 17th, 2007 8:06 pmForgive me for being dense, but why is it so 
imperative for ourspecie to "survive" at all costs? We have had our time 
on thisplanet and have managed to inflict more destruction upon it inthe 
last fifty years than it has sustained by other means in thelast fifty 
million years. And now we assert our "importance"once again by arrogantly 
thinking about how we can destroy yetanother planet in our God-like 
"right" to survive. Tis' farbetter - and more honorable and moral - that 
we expend ourenergies to fix this lovely blue planet before we 
considerdestroying another. Truly, we are such arrogant, vicious worms.
--posted by anastasios sarikas

69. July 17th, 2007 8:11 pmWith the Gott estimates - consistent with the 
rest of philosophy(including all of science) - posing the question limits 
theavailable answers. How long will humans last? That question 
isimmediately tied to the asker's current definition of `human'.You can 
get any answer you want by varying the details of thequestion that you 
ask.I don't mean to be derogatory! Asking questions is the fun part. Just 
don't get carried away with the significance of youranswers.
--posted by Adam Hammond

70. July 17th, 2007 9:27 pmIt is regrettable that Richard Gott is still 
purveying hisnonsense, but it is criminal that John Tierney has chosen 
todraw attention to it in the NYT. To see why it's nonsense, takea look at 
my article in Contemporary Physics, cited in Tierney'sarticle. Gott has 
never accepted the bet on dogs' lifetimes thatI offered him in my article. 
He would take that bet if heactually believed his own predictions, but 
it's obvious toanyone that he would lose.- Posted by Carlton M. 
Caves------------Response from John:I'll second Dr. Caves' recommendation 
that you read his critiqueof Dr. Gott's paper -- and then read the 
rebuttal by Dr. Montonand Dr. Kierland.Dr. Caves accused Dr. Gott of 
putting forward his Copernicanformula as "a universal rule, applicable no 
matter what otherinformation one has about the phenomenon in question." He 
alsowrote that Dr. Gott "rejects as irrelevant the process ofrational, 
scientific enquiry, replacing it with a single,universal statistical 
rule."Well, that would indeed be a dubious way to do science -- if Dr.Gott 
had ever done it. But he didn't. As I noted in my columnand my blog post, 
Dr. Gott clearly acknowledges that you canimprove on his formula when you 
have other information. In theirassessment of Dr. Caves' paper, Dr. Monton 
and Dr. Kierland arepolite -- they call his interpretation "uncharitable," 
not"criminal" -- but they flatly reject his criticism: "We intendto make 
clear that this is not the right way to understandGott's argument, and, 
moreover, Gott makes it pretty clear thatthis is not the right way to 
understand it."The bet that Dr. Caves mentions in his post was described 
in a2000 article by my colleague James Glanz. Dr. Caves compiled alist of 
24 dogs owned by colleagues and students of his at theUniversity of New 
Mexico, and then offered to bet Dr. Gott aboutthe longevity of the dogs -- 
but only of the six dogs that Dr.Caves picked because they were more than 
10 years old. Dr. Gottreplied that it was unfair to pick out a special 
sample of dogsand then apply the Copernican formula -- which is based on 
theassumption that you're not looking at a special situation. Thefair bet, 
he said, was to apply the Copernican formula to theentire sample of 24 
dogs listed by Dr. Caves. And the result, hewrites in his 2006 paper, is 
that unless any of the dogs breaksthe Guinness record for canine longevity 
(29.4 years), theCopernican formula has already accurately predicted 
thelongevity of all of the 24 dogs except the two youngest, whoseoutcome 
was still to be determined. Depending on the outcome ofthose two remaining 
cases, Dr. Gott figured he would end up withan accuracy rate of 92 percent 
(22/24), 96 percent (23/24) or100 percent -- right in line with the 
95-percent accuracyexpected of the Copernican formula.Which, to repeat, is 
not to say that the Copernican formula isthe one and only way to predict 
dogs' longevity. You could makemore precise predictions by gathering other 
data, like thelongevity of the average dog, or, better yet, the longevity 
ofthe particular species of dog in question. The point is that 
theCopernican formula enables you to make a prediction when youdon't have 
other data.---------
--posted by Carlton M Caves

71. July 17th, 2007 9:39 pmI thoroughly enjoy this formula. Obviously, it 
works best whenyou have no other information upon which to base your 
assessmentof time. Otherwise, you'd use that information, wouldn't you.But 
it's a rational way to go about the simple task of givingyourself 
limits.My concern, however, is as this formula would be applied to 
thehuman lifespan. Used on an infant, it would predict a child hasless 
than 40 years to live. Now, this is not a terribly badestimate for an 
infant when you consider mortality rates and thevulnerability of very 
small children. So, I would be willing tooverlook this.Applied to an aging 
human, however, you assume that an80-year-old man will live an additional 
2 years; a 100-year-oldman will live 2.5 more years. It seems to me that a 
flaw beginsto emerges here.This theory seems to hold that the timespan in 
question ages ina linear fashion. This might be true of political careers 
andBroadway musicals, but physical life-of humans, a galaxy or,say, a race 
of beings-seems to age exponentially. Babies getincreasingly healthy as 
they age; older humans tend to seehealth decrease accordingly. The 
universe accelerates and, intheory, would decelerate in similar fashion.Of 
course, we KNOW that 70 years is a reasonable, average humanlifespan, 
given decent health. We would have no need to applyGott's formula to 
anyone older than 68 years and 3 monthsold-since it's only useful if you 
DON'T known your limits.But knowing that it works in this fashion, doesn't 
it seem thatit would be MOST accurate when applied NEAR the very 
"specialmoment" that you should avoid applying it during, at the 
pointwhere the aging would be MOST linear?
--posted by Mikey

72. July 17th, 2007 11:17 pmIn regards to Gott's actual article, most of 
the responses gotWAY off track talking about politics and even science. 
His ideareally isn't SUPPOSED to be "science", but a neat stats trick. 
Iwas impressed that it worked so well, and I'm a physics gradstudent who 
works with statistics daily. The PHILOSOPHICquestions of when you can 
apply this trick is the interstingthing. I'd like to hear more discussion 
on that.In regards to Volt Rare's question "Is humanity mature enough 
togrow up?" the answer is no. Many of the responses above seemedto agree 
and blame the problem on Bush or corporate America, butPLEASE, those are 
"easy" targets -- the problem is ourselves.I'm surprised by the animosity 
of Maddy Wong's comment abovethat religious people should not be allowed 
to spread theirbeliefs on the new colonies if we want them to survive. I'd 
besurprised if a completely atheistic colony would do very well.If we 
don't believe in God and obey His laws (every bit as realas physical 
laws), we can always expect to have wars, hate, etc.It's nothing to be 
surpised or depressed about, and blamingpolitical leaders or the general 
attitude of the masses isn't ahelpful solution.
--posted by Glenn Strycker

73. July 18th, 2007 1:21 amIf the human species is a manifestation of 
protoplasmic life'sreproductive urge, then life ought to induce rut. As 
the hope oflife, humans can look for continued special care. If we 
don'trespond to rut by moving life into the available space, thenwe're 
doomed immediately.
--posted by Metarhyme

74. July 18th, 2007 4:10 amOne of the very important scientific intellects 
andstatisticians of the 20th century, Sir Ronald A. Fisher, of "TheDesign 
of Experiments" fame (and other accomplishments), wrotethat"Inductive 
inference is the only process known to us by whichessentially new 
knowledge comes into the world."That's the kind of assertion that keeps 
professionalphilosophers bickering "in thoughts more elevate...in 
wand'ringmazes lost"...forever.But "experience shows" that it seems to be 
fundamentally true,anyway.And Professor Gott's formula in its fundamentals 
seems not toinvolve magical numbers grabbed out of the air, but 
insteadobservation and measurements - the basics of 
"inductiveinference."So his Copernican Formula theory is very interesting. 
It might,if rigorously validated, serve as a kind of work-around 
inscientific investigations, which hold as the highestepistemological 
standard of lawful relations found in nature,the "functional relation" - 
conventionally a cause and effectrelation, where the cause is always a 
prior event. TheCopernican Formula might also work as a kind of 
heuristicdevice.The tricky word appears to be the word "thing." Many of 
the"things" scientists -and other people - have thought they 
havediscovered or demonstrated the existence of, down the years,have 
eventually been shown to have been names, not of events orprocesses in 
nature, but of "things we have made up" -explanatory fictions - which 
function as temporary stand-ins forthe actual event or explanations of an 
event or events, until abetter account is worked out.I'm convinced, 
though, that the good professor is going farbeyond his facts - as 
scientists are prone to do - if he says hecan show with his Copernican 
Formula that we'd better getcracking with a project of colonizing other 
planets.After all, the nearest star system to us, last time I checked,is 
Alph Centauri, which is 4.3 light years away. Then there isBarnard's star, 
at 6 light years. And then there's Wolf 359 at7.7 light years.And then 
there's...Oh well, for the full list of the twenty-sixclosest stars or 
star systems to 
earth,see:http://www.astro.wisc.edu/~dolan/constellations/extra/nearest.html
--posted by Louis Massano

75. July 18th, 2007 4:33 amAs Mr. Tierney points out, and as many posters 
have missed, Mr.Gott's theory is to be applied only when there isn't 
otherinformation. Like any tool, it's not always useful. However, itis 
still better than nothing.
--posted by Andrew Stead

76. July 18th, 2007 6:48 amGott's method relies on the property of power 
distributions:many small events, few big ones.-Imagine, as another 
example, that you'd have to choose betweenques in front of two telephone 
booths: one was already occupiedwhen you arrived and other was snatched 
right in front of yournose. You'd be better off wating for the later to 
finish.
--posted by thomas lill

77. July 18th, 2007 1:26 pmI wrote the following letter that was published 
in Nature in1994 about Gott's specious reasoning, and it still applies. 
Idon't know if Mr. Tierney is aware, but this same argument madethe front 
page of the Science Times at that time. It was wrongthen, and it is wrong 
now, although it makes good press:To the editor,"There are lies, damn lies 
and statistics" is one of thosecolorful phrases that bedevil poor workaday 
statisticians wholabor under the illusion that they actually contribute to 
theadvancement of scientific knowledge. Unfortunately, thestatistical 
methodology of astrophysicist Dr. John Gott,reported in Nature 363:315-319 
(1993), which purportedly enablesone to put statistical limits on the 
probable lifetime ofanything from human existence to Nature itself, 
breathes newlife into the saying.Dr. Gott claimed that, given the duration 
of existence ofanything, there is a 5% probability that it is in its first 
orlast 2.5% of existence. He uses this logic to predict, forexample, the 
duration of publication of Nature. Given thatNature has published for 123 
years, he projects the duration ofcontinued publication to be between 
123/39 = 3.2 years and123×39=4800 years, with 95% certainty. He then goes 
on topredict the future longevity of our species (5000 to 7.8 
millionyears), the probability we will colonize the galaxy and thefuture 
prospects of space travel.This technique would be a wonderful contribution 
to science wereit not based on a patently fallacious argument, almost as 
old asprobability itself. Dubbed the "Principle of Indifference" byJohn 
Maynard Keynes in the 1920s, and the "Principle ofInsufficient Reason" by 
Laplace in the early 1800s, it has itsorigins as far back as Leibniz in 
the 1600's (1) . Among othercounter-intuitive results, this principle can 
be used to justifythe prediction that after flipping a coin and finding a 
head,the probability of a head on the next toss is 2/3. (2) It hasthe been 
the source of many an apparent paradox and controversy,as alluded to by 
Keynes, "No other formula in the alchemy oflogic has exerted more 
astonishing powers. For its hasestablished the existence of God from total 
ignorance, and ithas measured with numerical precision the probability 
that thesun will rise tomorrow." (3) Perhaps more to the point, Kyburg,a 
philosopher of statistical inference, has been quoted asdescribing it as 
"the most notorious principle in the wholehistory of probability theory." 
(4)Simply put, the principle of indifference says that it you knownothing 
about a specified number of possible outcomes, you canassign them equal 
probability. This is exactly what Dr. Gottdoes when he assigns a 
probability of 2.5% to each of the 40segments of a hypothetical lifetime. 
There are many problemswith this seductively simple logic. The most 
fundamental one isthat, as Keynes said, this procedure creates knowledge 
(specificprobability statements) out of complete ignorance. The 
practicalproblem is that when applied in the problems that Dr. 
Gottaddresses, it can justify virtually any answer. Take the 
Natureprojection. If we are completely uncertain about the futurelength of 
publication, T, then we are equally uncertain aboutthe cube of that 
duration, T cubed. Using Dr. Gott's logic, wecan predict the 95% 
probability interval for T cubed as T3/39 to39T cubed. But that translates 
into a 95% probability intervalfor the future length of publication to be 
T/3.4 to 3.4T, or 42to 483 years, not 3 to 4800. By increasing the 
exponent, we cancome to the conclusion that we are 95% sure that the 
futurelength of anything will be exactly equal to the duration of itspast 
existence, T. Similarly, if we are ignorant aboutsuccessively increasing 
roots of T, we can conclude that we are95% sure that the future duration 
of anything will somewherebetween zero and infinity. These are the kind of 
difficultiesinherent in any argument based on the principle of 
indifference.On the positive side, all of us should be encouraged to 
learnthat there can be no meaningful conclusions where there is 
noinformation, and that the labors of scientists to predict suchthings as 
the survival of the human species cannot be supplantedby trivial (and in 
this case specious) statistical arguments.Sadly, however, I believe that 
this realization, together withthe superficial plausibility (and wide 
publicity) of Dr. Gott'swork, will do little to weaken the link in many 
people's mindsbetween "lies" and "statistics".Steven N. Goodman, MD, MHS, 
PhDAsoc. Professor of Biostatistics and EpidemiologyJohns Hopkins 
UniversityReferences1. Hacking I. The Emergence of Probability, 126, ( 
CambridgeUniv. Press, Cambridge,1975).2. Howson C, Urbach P. Scientific 
Reasoning: The BayesianApproach, 100, (Open Court, La Salle, Illlinois, 
1989).3. Keynes JM. A Treatise on Probability, 89, (Macmillan, 
London:1921)4. Oakes M. Statistical Inference: A commentary for the 
socialsciences, 40, (Wiley, New York, 1986).
--posted by Steve Goodman

78. July 18th, 2007 1:51 pmA different analysis: based on evidence from 
evolution andfossils and the like, we know that from bacteria evolved 
fishwhich evolved into land animals which evolved into 
humans.Consequently, bacteria have lived longer than humans and so 
havefish and all of the other "inferior" creatures. Based on thistheory, 
since humans have been around for the least amount oftime, they will be 
the first to go, followed by chimps and thenfish and bacteria will luckily 
be last. This goes against Darwinreasoning since evolution would be "going 
backwards," however,this is based on the assumption that humans are 
superior andtherefore more fit for survival than bacteria.However, IF 
(capital for a reason) this method for predictionsis true, than it must 
also follow that bacteria will live longerthan humans. Consequently, if 
anyone should be sent on a 1stclass trip to Mars it should numerous 
diverse species ofrapidly-dividing able-to-survive-anywhere bacteria. 
Bacteriawere able to survive the longest out of most if not all 
livingorganisms and should be first priority. That way, even if humansdie 
out after x many years, bacteria could restart what they didon 
Earth.Obviously, the bacteria has to be able to adapt and survive 
onanother planet, but if one species does, than it can rapidlymultiply and 
reproduce at which point we could introduce newspecies and try to have as 
many different self-sustainingspecies as possible on another planet.This 
approach would also solve any political problems betweenthe new colony.
--posted by Dmitriy Timerman

79. July 18th, 2007 3:58 pmI'm surprised that only one comment above seems 
to identify whatI find to be the biggest limiting factor of the usefulness 
ofGott's formula: the probable outcomes give enormous spans oftime! If a 
Broadway show has been running for, say, 10 years,then there's a 95% 
chance that it will continue running forsomewhere between six months and 
another decade (roughly). Sowhat? I agree that it's a neat statistical 
trick to play withone's friends (should one have any) or to discuss 
inphilosophical treatises (that I will enjoy reading, thanks forthe 
links), but the applied usefulness seems so limited as to benearly 
negligible in the real world.By the way, can we all agree to call this 
formula Gott's Dice?
--posted by mrgeof

80. July 18th, 2007 8:09 pmI would like to expand upon Mark Schroeder's 
excellent comment(#59).Dr. Gott's statistics require 3 assumptions. One, 
the givenprocess has a definite beginning in time. Two, the given 
processwill have a definite end. And three, the only information to beused 
concerning the given process is its known time of duration,regardless of 
what other information may exist about the processitself or similar 
processes.In essence, we treat the total (start to finish) duration as 
ifit is completely random: not only could the end occur at anytime, but it 
has an equal chance of ending at any given time. Wedo not assume to know 
what those chances are, only that they areconstant with time for a given 
process. All of the examples(thus far) of supposed problems with Dr. 
Gott's method areassuming non-randomness and a knowledge of how the 
chances (ofthe process ending) vary with time. Yes, we know that most 
ofthe processes we observe are not random in length. When (ifever) is it 
useful to treat them as such?Under Dr. Gott's assumptions, one can say the 
following with100% certainty: A process which is happening now will end 
atsome point in time between now and the infinite future. Equally,one 
could say with 0% certainty: A process which is happeningnow will end at 
the exact time T, where T is a single point intime that lies between now 
and the infinite future. Betweenthese two extremes, any desired level of 
certainty can becalculated, and each will require a different span of 
timeduring which the process may end. For a given current processduration, 
the longer the ending time span is allowed to be, thegreater the certainty 
of the process ending within that time.Now, to understand the significance 
of a given stated certainty(and the time span associated with that 
certainty), is a verydifferent problem. This will require a close look at 
the thirdassumption, which tells us that our only data point is 
theduration of the process at the present time.Let's say we have two 
timers that will count up to differentunknown times. Timer A been counting 
longer than Timer B. Wedecide to wait for them to finish and want to know 
our chancesof seeing the end. Since all we know about each timer is 
itscurrent duration, we can only state the probability that we willsee it 
stop in terms of its duration compared with how long weplan to wait. The 
longer a timer's duration, the longer we mustbe willing to wait to achieve 
a given certainty of seeing itfinish. We must wait longer for Timer A to 
achieve 95% certaintythan we do for Timer B.To put it simply, Dr. Gott's 
statistics are no more than astatement of how long we have to wait to be 
95% sure to see aprocess end if we treat its total duration as purely 
random. Thetime span for a given certainty is always increasing as 
theprocess duration increases. 95% sure today means waiting 1 year,and 95% 
sure at a later time means waiting 100 years. Remember,you always have to 
plan to wait an infinite amount of time to be100% sure of seeing the end. 
The small twist that Dr. Gottintroduces from the timer example is that he 
tells you how longyou may first close your eyes and then how long you must 
watchthe timers to be 95% sure of not missing the end.As an aside, Dr. 
Gott's statistical method can be applied inreverse to find the statistical 
certainty associated with aprocess having begun within a given time span. 
The data pointrequired to work backwards is the time span between when 
itbecame known that the process was occurring and the time atwhich the 
process ended. A slightly different method ofcalculation would be needed 
if the beginning and end times ofthe process were unknown, with only a 
known intermediate periodof duration, but in both cases a statistical 
certainty for agiven starting time frame could be calculated using 
theCopernican Principle.
--posted by PDS

81. July 19th, 2007 9:18 amI'm not sure why this is so controversial. It 
is almost commonsense and a simple probabilistic distribution based on 
limitedknowledge. It doesn't seem very useful, as it is more usefulfind 
relevant information to make the application of this theoryirrelevant.As 
an example on leaders, would you rather make a prediction onthe length of 
time of a presidential tenure based on how longthe current man has been in 
office or based on the rules of lawand past information on presidential 
term longevity? For otherleaders, like a dictator, I would want an 
equation that figuredthe probability of a coup, assasination, etc.As far 
as the human species, I don't find any problem with thespan of his 
prediction, when you consider evolution is anongoing process. How much 
longer will homo sapiens be the topspecies? Will we (probably) evolve into 
a higher species (with95% probability) in the time span Gott has 
allotted?Trying to find more specific knowledge is ever so much moreuseful 
than just a big time interval prediction, with suchthings as aliens and 
colonization. For instance we are busytrying to get more accurate numbers 
for the specifics inside thedrake equation by studying the universe.In 
summary, I would say you get little out with little in, andcertainly 
little information is either put in or received fromapplication of the 
copernician formula.
--posted by jsw

82. July 19th, 2007 11:40 amA recent Wired article, How NASA Screwed 
up(http://www.wired.com/science/space/magazine/15-06/ff_space_nasa), 
details a plausible impetus behind the push forunnecessary manned 
expeditions:"With the space station now almost universally viewed 
asworthless, the manned-space funders need a new boondoggle. Themoon-base 
idea, pushed by President Bush, fits the bill."Happy birthday Heinlein.
--posted by Baldwin

83. July 19th, 2007 11:49 amI think Caves and Goodman are right as far as 
the usefulness ofGott's idea goes but I think they miss something. Suppose 
Iobserve a process -- say a machine running or a timer thatdisplays time 
run -- and I ask myself what is the probabilityI've observed the timer in 
a middle of a run. If it is themiddle then it's easy to predict the end 
time (obvious)but howdo I know that for any particular timer? But consider 
a MonteCarlo -- after observing 25000 timers at random the average 
(orexpected value) of the probability of arriving in the middle ofrun time 
is .50069.
--posted by Steve Myers

84. July 19th, 2007 1:03 pmIt should be noted that Dr. Gott's statistical 
method is NOT amethod of prediction, whether or not he views it as 
such.Indeed, it cannot be used to predict, for he assumes from 
thebeginning that the total duration is completely random andtherefore can 
end at any time with equal probability.His method merely gives us a 
quantitative answer to thisquestion: "How surprised should I be (or, how 
`lucky' would Ihave to be) to see a process end, given that it has 
beenoccurring for X amount of time and I plan to watch for Y amountof 
time?" Another way of saying this is: "What are the chancesthat I will be 
around for a 'special' time in this process,given the times X and Y (as 
defined above) and assuming that Iam not seeing it at a special time now 
(i.e. assuming theCopernican Principle applies)?"Let's use the geyser 
example, and let's say that we have exactly1 hour to watch before we 
leave. Because the first geyser hasbeen active for 100 million years, it 
would certainly be asurprise if it suddenly stopped during our observation 
time. Our1 hour observation is clearly an extraordinarily small fractionof 
the geyser's full lifetime. We may be somewhat surprised ifthe 10 second 
geyser stopped, but that would be due to our extraassumptions about 
intergalactic geysers and has nothing to dowith our one and only data 
point (current process duration), towhich we have sworn complete 
loyalty.We would be much more surprised, and rightly so, if we returnedto 
Geyser Intergalactic Park in 100 million years and found our10 second 
geyser from the first trip (having never stopped) wasstill in business! Of 
course, it would be a retrospectivesurprise that we had witnessed such a 
long-lived geyser a mere10 seconds after its birth. It turns out that our 
originalobservation of its infancy was just as much of a rare event 
aswitnessing the end of the long-lived geyser.As this example shows, the 
real use of Dr. Gott's statistics isas a measure of our surprise at seeing 
(or not seeing) the endof a process in a given amount of time. In the 
reverse mode,where we are concerned with unknown beginnings instead 
ofendings, these statistics give us an expected measure ofsurprise if it 
turned out that the process began between twogiven points in time.
--posted by PDS

85. July 19th, 2007 2:07 pmGott's temporal Copernican principle is valid 
in most contexts,as long as one is not making the observation at a special 
time.Tierney's comments on estimating the duration of a marriage atthe 
wedding are exactly on the mark. You cannot usefullyestimate how long the 
marriage will last "because you've beeninvited to observe the beginning of 
this marriage, so you knowyou're seeing it at a special point in time".For 
exactly the same reason, Gott's formula is not useful inestimating the 
duration of the human race. Civilization neededto advance to a certain 
point before developing this formula. Ithas just been done, so we know 
that we are observing humanity ata special point in time. Thus, the basic 
requirement for theformula to be valid does not apply in estimating the 
lifetime ofthe human race.Note that Gott's formula will also be invalid 
for other eventsprimarily caused by humans, such as the extinction of a 
numberof species. One can test this by predicting the lifetime of 
thespecies of California condor or Northern white rhinoceros.
--posted by Philip Kaaret

86. July 19th, 2007 7:12 pmI'm sorry, Mr. Myers, but your Monte Carlo 
simulation (incomment #83) will not give the results which you have 
stated,although the discrepancy is a subtle one. You are either usingthe 
wrong set of initial conditions, or you are choosing thewrong quantity as 
your answer.Mr. Myers' result is perfectly correct for a 
coin-flippingproblem, where one flips a coin N times and divides the 
numberof times the coin comes up `heads' by N. The resulting answerwill 
approach the exact value of 0.5 as N approaches infinity.This shows 
empirically that the odds of obtaining the result ofheads is 50%, which we 
already knew to be true analytically.It is true that Dr. Gott's statistics 
also rely upon there beingonly 2 possible outcomes at each moment: the 
process continuesor it stops. However, Dr. Gott must begin with the 
assumptionthat he cannot assign a value to the odds of either outcome 
atany time, unlike the coin problem. If we assign a constantfinite value 
(no matter how small) to the odds of a processending at each moment, then 
we will have a process that has acharacteristic (relatively predictable) 
total time duration.This is the reason that we are surprised to observe a 
very longstreak of heads without any tails. Flip a million coins and 
youwill have thousands more occurrences of 2 heads in a row 
thanoccurrences of 8 heads in a row. The heads-only process has ahigh 
probability of a short life, although once the process hasstarted the odds 
are always %50 of it continuing to live on thenext flip. (If this is not 
helping to illustrate the point, thenlook into radioactive half-lives.) 
Thus, the resulting lifespandistribution for such a process is NOT the 
same as a uniformlyrandom distribution.Here is one Monte Carlo simulation 
that can be taken asrepresentative of Dr. Gott's ideas: Take a single 
photo of awall with 25000 timers which have already been running for 
arandom amount of time and are set to end at random times, all ofwhich are 
still running. Then wait for them all to stop.Calculate the ratio of the 
time displayed in the photo to thetotal time each of them ran. You will 
find that the average ofall the individual ratios is very close to 0.5, 
which is thesame as our coin-flipping scenario. However, in this case 
theaverage ratio is 0.5 simply because the individual ratios arerandomly 
distributed between 0 and 1, and not because the oddsof arriving in the 
middle were 50%.If it is true that "the average (or expected value) of 
theprobability of arriving in the middle of run time is .50069'',then 
50.069% of all of our timers will be found to have a ratioequal to 0.5 (or 
extremely close to that) and the rest of themsome other random ratio, 
which is certainly not the generalcase. Of our 25000 timers, most were 
very far away from themidpoint if our period of observation was short 
compared to theaverage final timer length. (In fact, not a single timer 
wasonly seen at the exact midpoint because our photograph had afinite 
exposure time; so it makes no sense to speak of observingor arriving at an 
exact midpoint in time.) We can check how manytimers went through their 
midpoints during the time our shutterwas open, and that number would be 
very close to zero if theshutter speed was 0.001 seconds and the average 
timer's totaltime was 100 years. We can calculate the expected probability 
ofobserving the middle, and that value equals the ratio of ourexposure 
time to the average timer's final time.Mr. Myers' answer overlooks this 
important length-of-observationto average-length-of-timer dependence. He 
has given us either oftwo wrong answers: (1) the average of all the 
individual elapsedtime to total time ratios, which merely restates our 
initialassumption of randomness, or (2) the "probability of arriving inthe 
middle of run time" for the single case where the exposuretime equals half 
the average timer's total time, instead of thegeneral solution.Dr. Gott's 
method tells us that we have a high probability ofseeing fewer long timers 
reaching their midpoints and seeingmore short timers reaching their 
midpoints. We observe along-lived timer for a small fraction of its life 
compared tothe (large) fraction we observe of a short-lived timer's 
life.The hard thing to wrap our minds around is this: while it istrue that 
we are more likely to observe a short timer'smidpoint, it is also true 
that the timers themselves all hadequal chances of being at their 
midpoints during our photo,regardless of their total lifespans.
--posted by PDS

87. July 19th, 2007 8:12 pmBut with the marriage example, one is 
incorporating the previousknowledge that most marriages don't end soon 
after they start,an assumption that with the geyser example we are not 
allowed tomake. There is always other knowledge available because theworld 
is infinitely full of possible data sets, it's just amatter of what we 
decide to believe is relevant.
--posted by mrgeof

88. July 19th, 2007 8:51 pmThe question is, what difference does it make 
if human lifeceases? Each one of us dies only once, and then it is all 
over.The continuation of humanity is irrelevant. Probability theoryis 
fascinating, but better applied to more important questions,like the odds 
that the fish on my dinner plate, that has beenthere for only ten seconds, 
will still be there six minutes fromnow.
--posted by Ian Campbell

89. July 20th, 2007 10:27 amIt has been about 65 million years since the 
last majorextinction. Using Gott's 1/40 methodology, we have about 
1.5million years before another extinction in likely. Why should wespend 
money now to development technology which we won't needfor 1.5 million 
years? With any reasonable rate of technologicalprogress, we should be 
able to deal with a similar extinction1.5 million years from now.
--posted by Bob Jackson

90. July 20th, 2007 12:08 pmThis is in the category of a parlor game. 
Fascinating, but notworth much.Betting on or trying to predict the 
continued existence ofhumanity would be more interesting if the potential 
causes ofdecline in population (and therefore the start of 
extermination)were handicapped for their potential impact on the 
supposedlyinevitable outcome.The nanny state appears to be a more likely 
culprit than doeswar at this point in time. Wars end, but entititlements, 
theyare forever.
--posted by A3K

91. July 20th, 2007 12:17 pmClarification: the average of a set of random 
numbers in (0,1)interval approaches .50 which is not the same situation as 
coinflips. My point was that Gott's rule is useless for predictinglife 
time of any timer. The question concerning run time ofanything is not 
really dependent on observation time (exposuretime). In the real world of 
predicting reliability of aproduction line given run times we use a known 
probabiltydistribution ( Weibull) or the Kaplan-Meier approach.
--posted by Steve Myers

92. July 20th, 2007 4:36 pmIn response to PDS, I'm not sure if I 
completely agree with you,however. Or maybe I do, but I don't agree with 
Gott and becameconfused with your point.Yes, it's true that in a series of 
coin flips, no matter whatthe previous cases were, the NEXT coin flip is 
50/50heads/tails. It is also true that if you flip coins and THENlook at 
the outcomes, longer streaks are less frequent thanshort streaks.So if we 
apply Gott's argument to radioactive decays, it DOESN'Twork. At any given 
moment, a given particle has a smallprobability of decaying, and that 
probability of decay isCOMPLETELY (as far as we know) independent of it's 
previouslifetime. In fact, this is probably the best counter-example 
toGott's idea, and few people have picked up on it. Gott'sargument is 
something like "the longer something has beenaround, the more likely it is 
to stay around longer". This isNOT true in a sense, because we are saying 
with radioactiveisotopes that there is no correlation between previous 
times,but each time interval has an equal probability of decay. 
Gott'sargument fails before we even begin.Where Gott's argument may be ok 
is in looking at phenomena forwhich there ISN'T a probability of death, 
but phenomena which heassumes already have a fixed lifetime. Then he 
assumes that weour observation must be a random sample in that interval. 
Allhis argument is saying is that our fixed delta_t observsationtime is 
probably in the middle 95% of the fixed total lifetimet, so we can predict 
based on the previous time elapsed what thetotal time will be.Where people 
get hung up is the word "prediction". Gott'sargument only works if the 
time interval was fixed -- for anyreal process, time intervals are 
somewhat random, somewhatdependent on other things. I don't think humans 
have the samedeath statistics as radioactive particles -- there's not 
reallya probability of death every second. Well, maybe there is 
(heartattacks, aneurisms, car accidents, and the like), but if youplot the 
average lifetime of people there is a peak, so it isn'tan exponential 
distribution like in decays.So I think that is where the philosophy come 
in: Gott is reallyjust saying that if you encounter a new phenomenon you 
shouldassume that the model is a "square" one -- the probability ofyour 
observation is equal for all times in the lifetime of theevent. Other 
people might instead say that "all things beingequal" that all death/decay 
statistics should be modeled afterradioactive decays. In this sense we 
cannot predict much ofanything without a large number of observations on 
identicalparticles (or systems). But maybe we CAN predict some things --as 
Gott does with other statistics, we could predict thehalf-life of a system 
with 95% confidence maybe. And in thatsense we could still be surprised if 
the particle X that hadbeen around 50 million years would decay before 
particle Y thathad been around 5 minutes decayed. Or would we? Hmm...
--posted by Glenn Strycker

93. July 21st, 2007 2:55 pmI especially liked this part of the original 
article:"In 1970 everyone figured we'd have humans on Mars by now, butwe 
haven't taken the opportunity," Dr. Gott says. "We should itdo soon, 
because colonizing other worlds is our best chance tohedge our bets and 
improve the survival prospects of ourspecies. Sooner or later something 
will get us if we stay on oneplanet. By the time we're in trouble and wish 
we had that colonyon Mars, it may be too late."Well- I'm only a geologist 
to parm' me but, just suppose we WASsmaht 'nuff and DID set up our colony 
on Mars. And then'something' came to `get us' -- RIGHT UP THERE?And -- 
gosh, I'm so picky but it's a professional necessity -- Inotice that an 
airliner crashed yesterday somewhere in theSouthern Hemisphere -- did Dr. 
Gott send out a prediction whileit was in flight, listing the 
probabilities for minimum andmaximum further duration of that flight? How 
about at the momentthe poor, doomed pilot added power on that rain-slicked 
runwayand tried for a go-around?What would Dr. Gott have predicted, at 
that `not particularlyspecial' moment?Hate it when that happens. But then 
I imagine that any system oftransport from here to Mars will have resolved 
any suchintermediate doubts on long-distance space travel........
--posted by Bob Tyson

94. July 21st, 2007 6:17 pmFor one thing, the very notion that an Elite 
could rule over theEarth from Mars is preposterous in the extreme and 
evidence of amind unworthy of being taken seriously.For another thing, 
World War II ended for the very simple reasonthat the Allies Won and the 
Axis Powers (Germany, Italy, andJapan) lost.With Germany and Italy, 
Nuclear Weapons played absolutely norole in granting the Allies victory. 
And as for Japan, they werealready crushed as a Military Power by the time 
the Bombsdropped on those two cities; and the war in the Pacificcertainly 
was going to end soon even without those expedients(they probably took 
months off the war at most).As for the Copernican Model, it seems 
unassailable in principleeven if its predictive power can sometimes be 
outdone by othermore exact and specific techniques.Other times, though, 
there's a strong stench of subjectivityinvolved in a predictive analysis; 
and in those cases theCopernican Principle (for all its unexactness) is 
vastlypreferable to an illusion of objectivity that in fact has nofirm 
footing in evidence or valid logic.
--posted by John Taylor

95. July 22nd, 2007 9:34 pmAnd if humans become extinct, ...? This will 
matter to whom?
--posted by William Madden

96. July 23rd, 2007 4:58 pmGott's theory is ridiculous and simply based on 
math.Every time his principle is applied, a slightly different resultis 
generated, depending on the time which has passed, meaningthat no actual 
accurate prediction could ever be consistentlyreached.Also, what defines a 
time as a specific time. Everytimesomething is measured, that becomes a 
specific time. Its aparadox which thwarts his assumption... applying his 
theorymeans it is automatically false and defeated.
--posted by Sean Lambert

97. July 24th, 2007 11:50 amBob Jackson is wrong about one thing. It's not 
been 65 millionyears since the last great extinction event. There's one 
goingon right now where at least half of all species living on thisplanet 
will be extinct before your grandchildren reach collegeage. This month's 
Scientific American has a good survey articleon this, along with a 
complementary piece on climate change.
--posted by Frank Lazar

98. July 28th, 2007 8:29 pmThe Geyser Park example is a bit of a swindle. 
If one sees a100-million-year-old geyser and a 10-second geyser, then 
thesubjective implication is that there is an equal priorlikelihood of 
seeing extremely long-lived geysers and veryshort-lived geysers. That is, 
this particular situation iscontrived to suggest that there is no 
characteristic scale forgeyser lifetimes, and so the implied underlying 
probabilitydistribution for geyser lifetime T (for currently 
shootinggeysers) is proportional to 1/T, as is explained in the 
linkedpapers. But this is the specific distribution that is necessaryto 
make Gott's prediction valid. So, this example "proves" Gottin the 
subjective sense simply by cleverly implying adistribution that makes it 
correct.Suppose, instead, that we entered Geyser Park and saw the10-second 
geyser, and dozens of geysers in the range 2 secondsto 9 seconds (and 
nothing else). In this case, we'd subjectivelyconclude that there is some 
upper limit to geyser lifetimes,probably not much more than 10 seconds, 
and therefore expect the10-second geyser most likely to end soon (well, I 
would). Here,a distribution is implied that has a characteristic 
geyserlifetime of perhaps 5-10 seconds.The point is that our subjective 
expectations are determined bythe distribution we see, which implies some 
specific underlyingdistribution. If we see nothing but the 10-second 
geyser, thenit's not clear to me that any expectation about future 
lifetimeis justified. If it stopped shooting after one second, one day,or 
one week I wouldn't be surprised. (Maybe I'd be surprised ifit turned out 
to be 100 million years.) Certainly, claiming thatthere's a 50-50 chance 
of it stopping before 10 more seconds isjust pulling a probability out of 
a hat.Gott's examples "verifying" his formula are also 
collectivelysomething of a swindle. The Copernican principle itself 
onlyestablishes that Gott's formula will hold true for a largeensemble of 
randomly selected processes. That is, for a largerandom selection, 95% 
will ultimately be found to have lifetimesbetween age/39 and age*39, 
whatever the current age is for anygiven process. This will be true for 
any underlyingdistribution, provided the lifespans of the ensemble 
arerandomly oriented relative to "now." Demonstrating this resultwith 
examples isn't terribly interesting, because this basicconsequence of the 
Copernican principle has no predictive powerin itself, but that's really 
all he does. He gives the examplesof ensembles of world leaders, Broadway 
shows, department-owneddogs, and so forth, but these ensembles are random 
selectionsfrom some overall distribution (with no consideration 
ofindividual ages ahead of time), and so it is almost a trivialresult that 
the Gott formula is found to hold true for 95% oftheir members. It is 
likewise not surprising that his dozen orso examples of individual 
processes also follow the formula asit can be presumed that these are all 
randomly selected fromsome ensemble of processes, also with no 
consideration of agebeforehand, and so a "hit" rate of even 100% for such 
a smallnumber is not surprising.The predictive power of Gott's formula 
comes from the assumptionthat the formula can still be applied to a given 
process evenafter the age of the process is known. This assumption is 
thatthe fraction of the total lifespan that an observed agerepresents is 
still randomly positioned from 0 to 1 even afterthe age is determined. 
This will generally be false because foralmost any actual distribution, 
there will be a correlationbetween the observed age and the resulting 
lifetime fraction.For example, if all current world leaders were serving 
(randomlyoriented) 4 year terms, then finding out that a given leader 
hadserved 1 year so far would establish that the fraction isexactly .25 
(not still anything from 0 to 1) and so thecorrelation is exact in this 
case (but note that the Gottformula will still hold for all the leaders 
collectively). Forother distributions the correlation will be weaker but 
stillpresent. Only for the specific 1/T probability distribution isthere 
no correlation, and so for that case it is still valid toassume that any 
value of the fraction is equally probable whenthe age is known. Only for 
that particular distribution is theGott future probability prediction 
valid.Gott's examples seem intended to establish that the 
effectivedistribution for current processes is 1/T, and this issupposedly 
"proved" because all the examples are seen to followthe formula. But 
taking random ensembles of all processes (fordifferent classes of 
processes) and comparing with the Gottformula does nothing to prove the 
1/T distribution because theGott formula will be true for random ensembles 
overallregardless of the distribution. And that is why his examples area 
swindle: the number and randomness of them over various agesare supposed 
to prove his formula's predictive power (See? Itholds for all ranges of 
ages of things!) but it is precisely therandomness over ages that kills 
the utility of his examples toprove anything, because with such a 
selection of examples theGott formula will be confirmed pretty much no 
matter what, andthus provide no proof--at all--of the more 
restrictiveassumption (i.e., 1/T distribution) that gives the 
formulapredictive power.The proper proof would be to take ensembles of 
processes offixed ages and then see what happens, for a variety of 
agesindependently. If we select a large random sample of currentprocesses 
that are 1 day old, and confirm the Gott formula forthis ensemble, the 
predictive power of the formula would beconfirmed (for 1 day old 
processes, absent any otherinformation). If Gott is confirmed also for 
1-week, 1-month,1-year processes and so on, then we could accept that 
thepredictive power of the formula is generally correct. Butapparently 
nothing like this kind of analysis has been done.In brief, to get 
predictive power from the Gott formula, we needto presume not just the 
Copernican principle but something closeto a 1/T probability distribution 
for lifetimes of currentprocesses as well. There is no subjective 
expectation that thisis generally so for totally unknown distributions 
(i.e. geyserexample), because we can concoct hypothetical situations 
tosubjectively imply any distribution (and I don't think a singleisolated 
sample of a distribution generates any reasonableexpectations). There is 
no objective evidence that this is soeither; Gott's examples only prove 
the Copernican principle ingeneral and not at all the 1/T distribution in 
particular.
--posted by D. R. Mizuno