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Entropy explained, with sheep (2016)

aatishb.com

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Re: Entropy explained, with sheep (2016)

#2
As a physicist, this is such a great explanation that's actually correct for a change. Entropy must be one of the if not the most misunderstood physical concept out there (along with Planck metrics like Planck energy or Planck length). Entropy is commonly used and written about by so many people that clearly lack the understanding of it that this blog post is a refreshing change.

Re: Entropy explained, with sheep (2016)

#4
If the entropy of the universe were to suddenly go in reverse would we be able to detect it or would our memory formation and perceptions being reversed make it indistinguishable from what we experience now?

Re: Entropy explained, with sheep (2016)

#5
Great explanation. What are the top theories for why the universe began in a low entropy state? The mere fact of that seems to contradict our current understanding of entropy. That implies that there is something very fundamental about the universe which we don't understand.

Re: Entropy explained, with sheep (2016)

#6
I recommend you the story "The Last Question", by Isaac Asimov[0], one of my favourite stories of all time. It's about how the question about reverting the direction of the entropy keeps rising on people, throughout the life of the universe.

[0] https://en.wikipedia.org/wiki/The_Last_Question

Re: Entropy explained, with sheep (2016)

#7
post #2

As a physicist, this is such a great explanation that's actually correct for a change. Entropy must be one of the if not the most misunderstood physical concept out there (along with Planck metrics like Planck energy or Planck length). Entropy is commonly used and written about by so many people that clearly lack the understanding of it that this blog post is a refreshing change.

The author is a physicist as well.

https://mobile.twitter.com/aatishb

Re: Entropy explained, with sheep (2016)

#8
post #4

If the entropy of the universe were to suddenly go in reverse would we be able to detect it or would our memory formation and perceptions being reversed make it indistinguishable from what we experience now?

This is a very good question.

Yes, time reversal would also reverse the process of our perception and memory, so we would experience time "moving forward" even if time were "moving" backward. We would experience entropy increasing even if entropy were "decreasing with time". (And it's perfectly valid to call the past "+t" and the future "-t"; the laws of physics don't care; if you do that, you'll see that entropy decreases as "t" increases, but despite changing definitions you'll still only have memories of a universe with lower entropy than the present).

This is one reason why it might be more correct to say that time doesn't move at all. We just perceive a direction of time wherever the universe has an entropy gradient along "the time axis".

Re: Entropy explained, with sheep (2016)

#9
Great article! I'm almost done with a PhD in physics and statistical physocs is still the hardest thing for me to wrap my mind around. Even more so than quantum and relativity. There's something about how unintuitive math becomes in ultra high dimension and the old timey feeling way that it was taught to me (steam engines and stuff) that makes it difficult to learn.

Re: Entropy explained, with sheep (2016)

#10

Great explanation. What are the top theories for why the universe began in a low entropy state? The mere fact of that seems to contradict our current understanding of entropy. That implies that there is something very fundamental about the universe which we don't understand.

There is a fantastic book by Leonard Susskind [0] that tackles this questions. His answer - rooted in string theory - is based on a "landscape of possibilities" and we happen to be in the place where all elementary particles (more specifically the Higgs) had the right energy configuration.

[0] The cosmic Landscape: https://www.amazon.com/Cosmic-Landscape-String-Illusion-Inte...

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