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A math equation that predicts the end of humanity:
The most mind-boggling controversy in the contemporary philosophy of science is the "doomsday argument," a claim that a mathematical formula can predict how long the human race will survive. It gives us even odds that our species will meet its end within the next 760 years.
The doomsday argument doesn't tell what's going to kill us — it just gives the date (very, very approximately).
Yet, I [William Poundstone] now believe the doomsday prediction merits serious attention — I've written my latest book about it. Start with J. Richard Gott III. He's a Princeton astrophysicist, one of several scholars who independently formulated the doomsday argument in the last decades of the 20th century. (Others are physicists Holger Bech Nielsen and Brandon Carter and philosopher John Leslie.) In 1969, Gott was a physics undergraduate fresh out of Harvard, spending the summer in Europe. At a visit to the Berlin Wall, he did a quick calculation and announced to a friend: The Berlin Wall will stand at least 2 and 2/3 more years but no more than 24 more years.
Demolition on the wall began 21 years later. This motivated Gott to write his method up. He published it in the journal Nature in 1993. There, Gott wrote of the future of humanity itself. He forecast a 95 percent chance that the human race would cease to exist within 12 to 18,000 years.
Not all Nature readers were convinced. "'There are lies, damn lies and statistics' is one of those colourful phrases that bedevil poor workaday statisticians," biostatistician Steven N. Goodman complained in a letter to Nature. "In my view, the statistical methodology of Gott ... breathes unfortunate new life into the saying."
Yet Gott and his predictions also received favorable attention in the[sic] New York Times[*] and the[sic] New Yorker[*] (where a profile of Gott was titled "How to Predict Everything"). Gott is an engaging storyteller with a Kentucky accent that's survived decades in the Ivy League. He has become a sort of scientific soothsayer, successfully predicting the runs of Broadway plays and when the Chicago White Sox would again win the World Series (they did in 2005).
Can it really be that easy to predict "everything"? It quickly became clear that 1) most scholars believe the doomsday argument is wrong, and 2) there is no consensus on why it's wrong. To this day, Gott's method, and a related one developed by Carter and Leslie, inspire a lively stream of journal articles.
You can read more about the doomsday debate on Quora
[*] The name of these publications do include the word "the" and should, therefore, be capitalized: The New York Times and The New Yorker, respectively.
(Score: 0) by Anonymous Coward on Tuesday July 09 2019, @12:20AM (3 children)
The point is there are very few proto-humans. Their estimates are poor, but their contribution to the total population of estimates is negligible because their population is low.
Looked at another way, suppose you were picking from the population of all humans. The only relevant information about the one you picked is the era in which they exist. Given that you picked someone matching your own era, what must the population look like to have the best probability of picking someone of that era?
That's all it is. It works remarkably well given the available information and gives you clear criteria for re-evaluating your model when new information is made available.
(Score: 2) by theluggage on Tuesday July 09 2019, @09:13AM (2 children)
...so they'd have said to themselves "if, in a few million years time, there were going to be billons of humans inhabiting the Earth, how come we've been born now, when there's only a few hundred of us? Ergo: we're the last generation!".
...I covered that scenario in my previous post. One small problem: you need a time machine to perform that test properly. Otherwise, you can only pick from the population of all humans born up until the current time so its a foregone conclusion you won't pick someone from 10,000 AD.
You're not getting the fundamental point: using your logic, every generation from the dawn of humanity to some hypothetical future galactic civilisation would conclude that they were the last humans.
The fallacy is that "you" (i.e. the person performing the test) are assuming that there is something inherently special about the time you are living in because, well, its you - so, big surprise, the result of that assumption is the false conclusion that there is something special about that time.
(Score: 2) by acid andy on Tuesday July 09 2019, @11:49AM (1 child)
I think you're right provided it remains a forever expanding population. If the world population stabilized at a large number and then had remained at that level for tens of thousands of years, you could expect to exist somewhere roughly halfway along that total number of humans that will ever live, suggesting a greater likelihood of tens of thousands of years of future survival. So, the most probable outcome always depends on what happens to the future growth rate of the population.
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 2) by theluggage on Wednesday July 10 2019, @12:27AM
So, basically, QED. You can't go fishing for a particular growth pattern that happens to work with the Bayesian Doomsday Model, especially a pattern that can't be valid if the Bayesian Doomsday Model is correct.
Then, still, someone 100, 1000, 5000, 10000... years into that future would incorrectly conclude that they were at the median point.
All of which is avoiding the elephant in the room, which is that the reason you haven't found yourself living in the year 802,901 is because the year 802,901 hasn't happened yet and the stork that delivered you didn't have a flux capacitor. The math assumes that you're standing outside time and picking a sample human from the totality of history, but the reality is that you can only pick someone who is alive at whatever time you make the measurement - so you'll always conclude that we're at 'peak humanity'.
...of course, if the population keeps on growing and we don't find another planet (or suitable substitute) we're basically fucked anyway, but that's just a coincidence.