
'Doomsday' Math Says Humanity May Have Just 760 Years Left - kgwgk
https://www.wsj.com/articles/doomsday-math-says-humanity-may-have-just-760-years-left-11561655839?mod=rsswn
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i_am_nomad
“Since it is equally likely that those of us living today are in the first or
second half of all past and future human births...”

Something about this predicate seems suspect. I can understand the reasoning,
but it seems like we’re mixing two separate domains of probability to arrive
at the conclusion, much like the common wrong answer to the Monty Hall
problem.

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RodgerTheGreat
One key problem with the premise is the assumption that your (lack of) priors
indicate a flat distribution. It sounds reasonable at face-value, but in the
bayesian framework it is actually a rather strong assumption that can be
leveraged to arrive at far less reasonable conclusions.

~~~
pessimizer
It's a credible sounding way to sneak in the law of averages.

edit: it only works for German tanks because you can reasonably assume that
the Germans aren't warehousing significantly more tanks than you've seen.

~~~
ex3xu
In lieu of German Tank serial numbers, Gott's original paper uses projections
from Ehrlich and Ehrlich's 1990 Population Explosion paper that the world's
population will top out at around 10 billion, then essentially cause a
dumpster fire and crash and burn. Obviously extremely speculative stuff that's
been sensationalized here.

~~~
AstralStorm
Why the dumpster fire and crash though instead of stability or expansion into
space for example?

Seems like a silly guess. Plus bad climate and famines and wars can stop it
much earlier than those 10 billion.

~~~
ex3xu
I can't get past the paywall to read the original Population Explosion paper
that Gott uses, but the dumpster fire premise seems to comes from the
assumption of tragedy-of-the-commons-style environmental degradation. The
Wikipedia on Ehrlich offers the following comment:

> When is an area overpopulated? When its population can't be maintained
> without rapidly depleting nonrenewable resources (or converting renewable
> resources into nonrenewable ones) and without degrading the capacity of the
> environment to support the population. In short, if the long-term carrying
> capacity of an area is clearly being degraded by its current human
> occupants, that area is overpopulated.

I agree with you that it is questionable set of assumptions, though I think
when considering some of issues humanity is facing in the realm of climate
change and water shortages, it's not an entirely untenable hypothesis.

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rladd
So let's say we did this way back in time, when only 100 humans had been born.
They could have been in the 1st half or the 2nd half. In either case, this
would seem to predict that no more than 100 more would be born, which is
clearly absurd.

What am I missing?

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ex3xu
I think you're missing that this columnist may in fact be a sensationalist
hack. As far as I can tell, nowhere in Gott's paper does he imply that we will
end in less than a thousand years. From a quick scan of the paper, Gott's most
incendiary statement is that there is a 95% confidence interval that our
remaining species lifetime is in the range of 12 to 7.8e6 years.

If anyone wants to check for themselves, hopefully it's not against HN rules
to link the paper: [https://sci-hub.tw/10.1038/363315a0](https://sci-
hub.tw/10.1038/363315a0)

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beefman
There's an assumption here that you're sampling an ergodic process.[1] 'All
tanks the Germans have built so far' satisfies this assumption (assuming equal
likelihood of capture). 'All tanks the Germans will ever build' doesn't. In
other words, you can't sample the 200Bth human because they haven't been born
yet, and this isn't evidence they will never be born.

[1]
[https://en.wikipedia.org/wiki/Stationary_ergodic_process](https://en.wikipedia.org/wiki/Stationary_ergodic_process)

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AstralStorm
It can be limit process though, like a sigmoid, that eventually becomes
stationary. That is a big assumption though. Evolution was punctuated by such
seeming stable domains only to reset everything once conditions changed... Or
push past previously known barriers. This including technical progress early
in human history. The population function over long time is not exactly smooth
either.

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verdex_phone
Im pretty sure I watched a numberphile video on this. I'm having trouble
googling it. Anyone know the video I'm talking about?

This is the sort of thing that belongs on HN, but not WSJ. WSJ should be
talking about the privacy issues they vaguely touch on before going back to
talking about doomsday by statistical argument.

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anm89
"Equation that powers today's computer algorithms"

Uh, what? I closed the tab at this point.

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tptacek
Perhaps if you open the tab back up, you'll find your question answered.

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kediz
Given that we have already experience 5 consecutive "500 years summer" in the
past 5 years, we might be living in the last 7 years of our 760 years.

