Roger Penrose - Before the Big Bang

In summary, Roger Penrose's Weyl curvature hypothesis suggests that entropy is highest in regions of the universe that are clumped together, and decreases as the universe expands.
  • #1
Sumo
28
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http://www.youtube.com/watch?v=fJ-D5AUGVcI&hl=de"
http://www.youtube.com/watch?v=inzgHjEVxAc&feature=channel"
http://www.youtube.com/watch?v=WD3BWt85bxA&feature=channel"
http://www.youtube.com/watch?v=YXDSCEX5wE8&feature=channel"
http://www.youtube.com/watch?v=YX30dxKdJkc&NR=1"
http://www.youtube.com/watch?v=aNS_8WTYVuM&NR=1"
http://www.youtube.com/watch?v=6mV6WnA52wQ&NR=1"
http://www.youtube.com/watch?v=LXYLLG7VkoI&NR=1"
http://www.youtube.com/watch?v=br1zHYH2hvA&NR=1"

This is an interesting video lecture by Roger Penrose talking about his Weyl Curvature Hypothesis. I found most of it fairly easy to understand. Maybe if someone can explain to me one thing: He talks about how entropy at the beginning of the universe was low or zero. But he also says (I think) that the background radiation shows thermal equilibrium, and that the early universe was almost perfectly homogeneous. Doesn't this mean that entropy was high?
 
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  • #2
Sumo said:
http://www.youtube.com/watch?v=fJ-D5AUGVcI&hl=de"
http://www.youtube.com/watch?v=inzgHjEVxAc&feature=channel"
http://www.youtube.com/watch?v=WD3BWt85bxA&feature=channel"
http://www.youtube.com/watch?v=YXDSCEX5wE8&feature=channel"
http://www.youtube.com/watch?v=YX30dxKdJkc&NR=1"
http://www.youtube.com/watch?v=aNS_8WTYVuM&NR=1"
http://www.youtube.com/watch?v=6mV6WnA52wQ&NR=1"
http://www.youtube.com/watch?v=LXYLLG7VkoI&NR=1"
http://www.youtube.com/watch?v=br1zHYH2hvA&NR=1"

This is an interesting video lecture by Roger Penrose talking about his Weyl Curvature Hypothesis. I found most of it fairly easy to understand. Maybe if someone can explain to me one thing: He talks about how entropy at the beginning of the universe was low or zero. But he also says (I think) that the background radiation shows thermal equilibrium, and that the early universe was almost perfectly homogeneous. Doesn't this mean that entropy was high?

I think the idea is that becuase one constrains the weyl cuvature to some value(zero?) this means that despite the universe being in a thermal state it still is in a very special state so the entropy is low. But it does seem confusing.
 
Last edited by a moderator:
  • #3
Finbar said:
I think the idea is that becuase one constrains the weyl cuvature to some value(zero?) this means that despite the universe being in a thermal state it still is in a very special state so the entropy is low. But it does seem confusing.

Penrose thinks that gravitational entropy is low for uniformly distributed matter and high for clumped matter. See

https://www.physicsforums.com/showthread.php?p=1800223#post1800223
https://www.physicsforums.com/showthread.php?p=1577616#post1577616.
 
  • #4
Maybe I'm confused.. Who disagrees with that? That clumping increases entropy has been standard lore and textbook for a long time now. In the cases we can actually calculate in, that's always been the case.
 
  • #5
Haelfix said:
That clumping increases entropy has been standard lore and textbook for a long time now.
Penrose goes further than just that. He identifies the relevant degrees of freedom for gravitational entropy as the Weyl curvature tensor. As pointed out in the thread linked above by George, with a cyclic model for the Universe, he needs the entropy to be constant basically. So if I understand anything to his claim, the entropy flows to the gravitational field, and it takes an enormous change in thermodynamical entropy to make up a small change in the Weyl curvature so you get a very long process to transfer in this direction, while according to him when the Universe becomes conformal and undergoes a transition to the "next big bang", it takes literally no time since there is no reference for any kind of clock.
 
  • #6
met a man from cambridge today, live in kansas city.
 

1. What is Roger Penrose's theory about the Big Bang?

Roger Penrose's theory, known as Conformal Cyclic Cosmology, suggests that the universe goes through an infinite cycle of expansion and contraction, with each cycle beginning with a Big Bang and ending with a Big Crunch.

2. How does Penrose's theory differ from the traditional Big Bang theory?

Penrose's theory differs from the traditional Big Bang theory in that it does not propose a single initial singularity, but rather a series of cycles in which the universe expands and contracts infinitely.

3. What evidence supports Penrose's theory?

Penrose's theory is supported by observations of the cosmic microwave background radiation, which shows "echoes" of previous universes in the form of circular patterns. Additionally, his theory addresses some of the issues and paradoxes present in the traditional Big Bang theory.

4. Is Penrose's theory widely accepted by the scientific community?

While Penrose's theory has gained some traction in the scientific community, it is still considered a controversial and speculative theory. More research and evidence is needed to fully support or disprove his ideas.

5. How does Penrose's theory impact our understanding of the origins of the universe?

Penrose's theory challenges the traditional notion of a singular beginning of the universe, suggesting that the universe has always existed in some form. It also raises questions about the concept of time and the potential for multiple universes beyond our own.

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