Alan Guth on Entropy and the Arrow of Time at the FQXi conference 2014 in Vieques
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Updated version of Alan Guth's talk -- now with slides! -- can be found here, https://www.youtube.com/watch?v=AmamlnbDX9I fqxi.org The past century in physics seems to lead in a surprising direction: away from physics as a description of objects and their interactions, and towards physics as a description of the evolution of information. Is this the correct way to think about physics and the physical world? What is information? What does the term "information" even mean? What role does information play in quantum gravity, cosmology, thermodynamics, life and consciousness, and what links does it provide between these areas? FQXi's international, interdisciplinary conference on the Physics of Information brought together leading researchers to discuss the significance, meaning, and uses of information in physics.
Comments
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Did anybody else spot the error with Guth's reasoning regarding the probability distribution on the real number line? It took me a while but then the error in his reasoning became blatantly obvious. It seems strange for a guy as smart as him, but hey, maybe I misunderstood his reasoning. I'm happy for somebody to correct me if that is the case.
But as far as I see it, he says that both arguments are irrefutable and hence it is a proof by contradiction. I disagree, the second argument seems patently false because the fact that A is a finite number does NOT mean that B has a probability of 1 of being larger.
The difference between A and infinity is precisely the same as the difference between A and minus infinity, hence the probability remains 1/2 in both lines of reasoning.
I can only assume that he was being sloppy and meant that there cannot be a uniform probability distribution across the POSITIVE real number line. However this in itself leads to contradictions, which is why I think that any arguments regarding infinities (outside of set theory) cannot be taken seriously. -
Not an expert, but I have the uneasy feeling that there is a subtle (Dr. Guth is a brilliant man, so it can't be an obvious fallacy) fallacy in this argument. Not being an expert, I may be wrong, but I think there is some irreducible circularity in this argument. As near as I can locate it, it lies in the actual concept of probability itself.
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Good talk. But the CPT theorem is NOT universally applicable, e.g. inside black holes or other singularities or inside some Dark matter island
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"All of the energy and matter that existed still exists. Matter does not create energy of itself. The actions of matter enable energy to become manifest".
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7:26 "non-interacting particles"....well he did say this was not based on reality.
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Fire the camera operator. But to be fair, great job capturing the blank whiteboard in the background.
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I think it's great there are no slides
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Guth says @13:25"yes we have indeed generated an arrow of time simply by waiting." But surely waiting implies an arrow of time? Naively, this appears circular.
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I may not understand this lecture. But in essence I think he says that time is an emerging property of essentially the difference of the internal states of a system. The system does not care about the sign of the time. However, it is in our universe fixed as a positive + sign. Am I right or did I completely misunderstood this lecture?
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Prof. Guth it good
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These talks are awesome, thank you
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there needs to be video of the slides.
for next time please!
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