we may only have another 5-billion, so make every year count!

[spoonless]

It seems that top notch physicists have now discovered Nick Bostrom's ingenius "Doomsday Argument".

Eternal Inflation Predicts That Time Will End
http://arxiv.org/abs/1009.4698

"If you accept that the end of time is a real event that could happen to you, the change in odds is not surprising: although the coin is fair, some people who are put to sleep for a long time never wake up because
they run into the end of time first. So upon waking up and discovering that the world has not ended, it is more likely that you have slept for a short time. You have obtained additional information upon waking—the information that time has not stopped—and that changes the probabilities. However, if you refuse to believe that time can end, there is a contradiction. The odds cannot change unless you obtain additional information. But if all sleepers wake, then the fact that you woke up does not supply you with new information."

Lending some weight to this theory is the fact that both Peter Woit and Lubos Motl think the paper is complete nonsense (Motl's rant on it is particularly entertaining and vacuous), since both of them are idiots (although usually in polar opposite ways)!

I've always thought of Raphael Bousso as a better physicist than ex physicist Lubos Motl was, and certainly better than mathematics lecturer Peter Woit. I suppose that doesn't guarantee that it's right though.

Normally I wouldn't pay much attention to a headline like this, but Bousso is actually someone I have a lot of respect for. And to add to that, I have found Bostrom's Doomsday Arguments in the past fairly persuasive (at least more convincing than not), which have a similar flavor... although Bostrom's arguments were far less technical in nature. This may give a more solid, physical basis to the idea that being a good Bayesian entails believing we are all doomed.

Comments

[onhava.livejournal.com]

They did provide a physical interpretation of how they actually think it will end. Namely, that observers get thermalized when they run into the event horizon.

Only for the causal patch measure, whereas their argument claims to be more general. And I really don't see any physical reason in the causal patch measure to think that these observers are thermalized; as you say, infalling observers shouldn't notice if they cross a horizon. So I find this less than convincing.

Aside from that very brief discussion of the causal patch measure where they at least try to connect with physics, the rest of the paper really seems to be saying something much more radical. They say very explicitly:

Usually, it is assumed that spacetime is inextendable [23]. But the cutoffs we considered regulate eternal inflation by restricting to a subset of the full spacetime. Probabilities are fundamentally defined in terms of the relative abundance of events and histories in the subset. Then the fact that spacetime is extendible is itself a physical feature that can become part of an observer’s history.

This is really, really radical. They're saying that spacetime could be extendable -- there could be no physical obstruction to just continuing to propagate further into the future -- but time could end anyway. It's hard to overstate what an extreme departure that is from everything we know about physics. And truly radical ideas in physics are, to zeroth order, always completely wrong.