Comments on: Anthropic Breakthrough

By: Overcoming Bias : Seek Criticism

Overcoming Bias : Seek Criticism — Thu, 17 Mar 2011 16:02:55 +0000

[...] Bousso (co-author of that Anthropic breakthrough I raved about in ‘08) reviews the book in Science, and seems to [...]

By: Overcoming Bias : Aliens Not So Strange

Overcoming Bias : Aliens Not So Strange — Mon, 07 Feb 2011 00:48:31 +0000

[...] This view finds some support in the fact that the assumption that life tends to evolve via entropy of sunlight hitting dust predicts many cosmological parameters. In ‘08 I reported: [...]

By: Robin Hanson

Robin Hanson — Wed, 03 Mar 2010 18:52:45 +0000

I just added to this post.

By: Will Woods

Will Woods — Thu, 22 May 2008 16:07:03 +0000

http://www.reuters.com/article/scienceNews/idUSN2030386720080520

Zoink!

By: Russell Wallace

Russell Wallace — Thu, 22 May 2008 14:18:25 +0000

The causal diamond is the amount of stuff in the future light cone (taking into account the eventual disappearance of things over the horizon of accelerating expansion). But even if it weren’t, the difference only matters to a small constant factor, which disappears in the noise in this context. What’s important here is the big-O size, and that’s the same for cones and diamonds.

By: Robin Hanson

Robin Hanson — Thu, 22 May 2008 13:40:17 +0000

Russell, cones and diamonds are different shapes, so integrals over them could be different.

By: Russell Wallace

Russell Wallace — Thu, 22 May 2008 13:30:25 +0000

Robin – I don’t think I understand your reasoning. The causal entropic principle says a larger causal diamond gives higher weight because it contains more dust-produced entropy. I’m suggesting it gives higher weight because it increases the total number of observers resulting from each origin of intelligent life. I think the two give the same predictions at least for a causal diamond no larger than the one we observe, i.e. cosmological constant as low as 1e-123. Am I missing something?

By: Robin Hanson

Robin Hanson — Thu, 22 May 2008 11:48:15 +0000

Russell, your concept would suggest the chance to find observers at any one place would be the integrated entropy production in the back light cone from that place. While plausible, this would seem to make different predictions from the causal diamond used in the causal entropic principle.

By: Eric Baum

Eric Baum — Thu, 22 May 2008 11:36:20 +0000

God has chosen the world that is the most perfect, that is to say, the one that is at the same time the simplest in hypotheses and the richest in phenomena.
– Gottfried Von Liebniz

By: Russell Wallace

Russell Wallace — Thu, 22 May 2008 04:29:09 +0000

Final afterthought for tonight:

Why would the above reasoning not push, or at least float, the cosmological constant even lower than the observed value? The authors’ reasoning is that additional galaxies reachable in later time are mostly “used up”, so don’t provide much additional weighting. However, it’s been suggested that burnt-out stars retain most of their energy value to an advanced civilization (e.g. feeding helium etc into black holes for energy).

Suppose intelligent life is rare, but not that rare, and over distances substantially larger than our horizon, expanding bubbles of civilization are likely to bump into each other, thereby negating further weight bias.

By that interpretation – with additional disclaimer, obviously this is even more extremely tentative than my earlier comment – the above papers just might constitute the very first evidence for a lower bound on the frequency of intelligent life.