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Black Hole Merger Model

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18 years 2 months ago #26827 by Son Goku
Replied by Son Goku on topic Re: Black Hole Merger Model

Can you recommend any literature on Weyl or Ricci Curvature ? I'd like to follow this up a bit more.

If you have Roger Penrose's "Road to Reality" then there is an excellent discussion on it in Chapter 17 or 18, can't remember which.
He then goes on to talk about Weyl and Ricci curvature in his chapter on entropy.
Even his other book "The Emporer's New Mind", talks about it a bit.

(Believe it or not 90% of all entropy in the universe came from Weyl curavture being replaced by Ricci)

On a more advanced level Wald's "General Relativity" is pretty much the bible on the differences and relationships between Ricci and Weyl curvature.

One of the biggest areas of research in GR today is what spacetime does when there is no matter.
Since matter only causes Ricci Curvature, Weyl Curvature can do what it wants independant of matter.
When you get rid of all matter space is Ricci-flat and then you have to talk about just Weyl.
What Weyl did on its own was one of Einstein's favourite questions, as seen in this famous picture:

The equation reads "Ricci Curvature = 0?".
It then went on to discuss Weyl Curvature.

A final down to Earth example of both, if I'm not making this post too long, is the Moon and the Earth's tide.
Astronauts on the Moon's surface jump up and fall down because of Ricci Curvature. However this Ricci curvature causes Weyl Curvature and the Weyl Curavture causes the Earth's tides.

I still think nature has something strange to throw at us regarding 'gravitational waves'. I think there is still something that we're missing. "Science without observation" and all that - why have gravitational waves not been observed yet ? - and yes I know it's not a simple matter to observe.

We still have a while to go in understanding Weyl Curvature's role in the universe, so I wouldn't be surprised if there were surprises.

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18 years 2 months ago #26834 by JohnMurphy
Replied by JohnMurphy on topic Re: Black Hole Merger Model
Son Goku,

I do have Roger Penrose's "Road to Reality", haven't read it all yet - it's a selective reading book really, that you dip in and out of for relevant info, a bit tough to read all in one go. I'll check out the chapters you mention - thanks for that. I'll also see if I can pick up a copy of Wald's "General Relativity" at Amazon.

While were at it, what are your impressions on particles of 'space'?, i.e. that space itself must have a quantum existence somewhere near the planck scale. At this scale there would be more space particles on the head of a pin (paraphrasing) than there are all other particles in the entire universe. But maybe that's for another day and another post.

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Irish Astronomical Society
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18 years 2 months ago #26898 by Son Goku
Replied by Son Goku on topic Re: Black Hole Merger Model

I do have Roger Penrose's "Road to Reality", haven't read it all yet - it's a selective reading book really, that you dip in and out of for relevant info, a bit tough to read all in one go.

I know what you mean, very mathematical. Although it's a fantastic guide to physics. The only downside is that he spends three chapters on Quantum Mechanics, but only one chapter on Quantum Field Theory, which I find odd because most of modern theoretical physics is Quantum Field Theory.

While were at it, what are your impressions on particles of 'space'?, i.e. that space itself must have a quantum existence somewhere near the planck scale. At this scale there would be more space particles on the head of a pin (paraphrasing) than there are all other particles in the entire universe. But maybe that's for another day and another post.

It's better a better idea than the graviton I think and has managed to give predictions. However I'm still firmly part of what is called the "Third Road", advocated by Roger Penrose and a few other British Physicists.
I could explain this if you wish, it usually makes for a good discussion on Theoretical Physics.

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18 years 2 months ago #26944 by JohnMurphy
Replied by JohnMurphy on topic Re: Black Hole Merger Model

However I'm still firmly part of what is called the "Third Road", advocated by Roger Penrose and a few other British Physicists.


Is this third road anything to do with Twistors ?
If you can elaborate more or point me to a descriptive link of "Third Road" then I'd appreciate it.

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18 years 2 months ago #27009 by Son Goku
Replied by Son Goku on topic Re: Black Hole Merger Model
Basically a greater understanding of decoherence, wavefunction "jumping" and QFT and GR's relationship is needed before we can continue.

Penrose's Twistors were part of this, as he rewrote GR in the mathematics of QFT to make comparison easier.

The litrature is few and far between, because not many people are in this area. (Simply because it doesn't grab most people's attention.)

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18 years 2 months ago #27029 by JohnMurphy
Replied by JohnMurphy on topic Re: Black Hole Merger Model
I've a bit more reading to do then.

Thanks for the pointers.

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John Murphy
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