We’re Doomed
Permission to panic sir
Posted on 16 Jun 25
by John Ridgway
In the summer of 1969, a young astrophysics graduate, J. Richard Gott III, was touring Europe and found himself gazing upon the Berlin Wall. Pondering just how long it would take before it would finally be pulled down, he turned to his touring companion and confidently proclaimed that it would last at least two and two thirds more years but no more than 24. In 1987, President Reagan said ‘Mr Gorbachev, tear down this wall!’, and within five years the wall was gone. That’s within 23 years of Gott making his 24 year prediction.
So was Gott a crack political analyst, or did he possess a crystal ball? Neither, in fact. He was simply employing a principle he had learned at college, i.e. that we have no reason to presuppose that we occupy a special place in the universe. This principle, known as the Copernican principle, can be applied in both space and time, and is not restricted to cosmological questions. Gott just reasoned that he shouldn’t assume he was living in any special epoch as far as the Berlin Wall was concerned. That is to say, he wasn’t likely to be living during the very early life of a long surviving edifice, nor at the very end of a shorter-lived one. The likelihood instead was that the wall’s future would be as long as its past (to be precise, the probabilities would take the form of a normal distribution centred upon Gott’s Copernican judgement).
In 1993 Gott submitted a paper to Nature describing his reasoning (which he referred to as the ‘delta t argument’) and, much to everyone’s horror, Nature accepted it. Experts of all persuasions dismissed it as facile numerology, unworthy of a prestigious magazine’s attention. The problem, however, is that the technique works, and has been successful in predicting everything from Broadway show runs to the future value of stock market investments. Indeed, the idea has been independently developed by others in a number of forms (all of them essentially variations on Bayesian reasoning). The techniques now go by the name Doomsday Argument, principally because they are used to predict how much longer we can expect the human race to survive.
https://cliscep.com/2025/06/16/were-doomed/
