Finally, something which sounds like the correct answer to the thread title, if gravity leakage from parallel branes is not considered.
There was a program on BBC2 last night - Universe - God Star, usual glib physicist 😉 walking around in deserts this time both rock and sand types. Timing mentioned. I didn't watch all of it but may spin it up on catch up. A take on it all I have not come across before. About 8min in
The universe is dark. It has dark matter. Appears to be a glob of it that starts producing strands. This results in a lattice, sort of chaotic spiders web. There is hydrogen and helium around. Stars form where these strands cross. All hot blue monsters. Temperature mentioned - from the web it ranges between 10k and 50k Not sure which one he mentioned. 100k? Due to type they last around 1,000,000 years. Element formation figures but mentioned gold needs collisions. This is the era where light appears.
It then went on to the point when light ceases to exist. This implies not enough hydrogen? The initial amount is all used up. Fossil stars etc. The solar probe parts are interesting.
There is an OU links page associated with the program
https://www.bbc.co.uk/programmes/b07591mr
A frustrating one
https://www.bbc.co.uk/programmes/p03ms8j9
a snipit and the entire program isn't available. Me -I wonder if that comment is fair. I'd say no.
The universe is dark. It has dark matter. Appears to be a glob of it that starts producing strands. This results in a lattice, sort of chaotic spiders web. There is hydrogen and helium around. Stars form where these strands cross. All hot blue monsters. Temperature mentioned - from the web it ranges between 10k and 50k Not sure which one he mentioned. 100k? Due to type they last around 1,000,000 years. Element formation figures but mentioned gold needs collisions. This is the era where light appears.
It then went on to the point when light ceases to exist. This implies not enough hydrogen? The initial amount is all used up. Fossil stars etc. The solar probe parts are interesting.
There is an OU links page associated with the program
https://www.bbc.co.uk/programmes/b07591mr
A frustrating one
https://www.bbc.co.uk/programmes/p03ms8j9
a snipit and the entire program isn't available. Me -I wonder if that comment is fair. I'd say no.
I better run down on Einstien's biggest blunder
https://www.wondriumdaily.com/what-was-einsteins-cosmological-constant/
https://www.wondriumdaily.com/what-was-einsteins-cosmological-constant/
@gpauk I've admitted many times in the past that I know nothing about cosmology.
Intelligence comes no more artificial than mine! 🤓
I merely assemble information I find in books and on the net, edit it, and try to present it in a digestible form to other interested parties.
I had hoped that the silent majority, including @tobydog, would be benefiting from my efforts.
Over to you guys, let's see your contributions to the thread! 😉
Intelligence comes no more artificial than mine! 🤓
I merely assemble information I find in books and on the net, edit it, and try to present it in a digestible form to other interested parties.
I had hoped that the silent majority, including @tobydog, would be benefiting from my efforts.
Over to you guys, let's see your contributions to the thread! 😉
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How dare you criticise our own, very modest, Prof. Brian Cox! 😱
Watch the programme here folks: https://www.bbc.co.uk/iplayer/episode/p09ybpb8/universe-series-1-1-the-sun-god-star
There is a paper with a more general discussion of this area here
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6395782/
Pesky black holes crop up. There are also some papers that cost one way or another.
A Feynman lecture - not related
https://www.feynmanlectures.caltech.edu/III_03.html
Pesky infinities. Instances of similar and naught mathematics. Mentioned in some of the interviews 😉 and they know it.
https://www.quantamagazine.org/tag/quantum-physics/page/1
Interesting
https://www.livescience.com/runaway...space-with-a-trail-of-newborn-stars-behind-it
https://scitechdaily.com/hubble-fin...ng-our-milky-way-galaxy/?utm_content=cmp-true
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6395782/
Pesky black holes crop up. There are also some papers that cost one way or another.
A Feynman lecture - not related
https://www.feynmanlectures.caltech.edu/III_03.html
Pesky infinities. Instances of similar and naught mathematics. Mentioned in some of the interviews 😉 and they know it.
https://www.quantamagazine.org/tag/quantum-physics/page/1
Interesting
https://www.livescience.com/runaway...space-with-a-trail-of-newborn-stars-behind-it
https://scitechdaily.com/hubble-fin...ng-our-milky-way-galaxy/?utm_content=cmp-true
It seems from odd comments that black holes a beginning to be a problem for them. They are so well understood??????
@AjohnL, I cannot arrange the words of your last post into any meaningful order! Perhaps you are dyslexic?
I am busy reading Physics, and particularly, Mathematics, ATM. Portsmouth Central Library occasionally surprises me.
Though I have little time for String Theory. Absolute rotten bunk.
AFAIK, when Einstein and Hilbert were struggling with non-conservation of Energy in Gravity, along came Emmy Noether to the rescue:
https://en.wikipedia.org/wiki/Emmy_Noether
https://www.bbc.co.uk/programmes/m00025bw
The founder of modern Physics.
"Ecoutez et apprenez" as we say. (Listen and Learn). It's a Guage problem. Or perhaps a question of invariant theory.
In retrospect, Einstein would have preferred that name over General Relativity. 🙂
I am busy reading Physics, and particularly, Mathematics, ATM. Portsmouth Central Library occasionally surprises me.
Though I have little time for String Theory. Absolute rotten bunk.
AFAIK, when Einstein and Hilbert were struggling with non-conservation of Energy in Gravity, along came Emmy Noether to the rescue:
https://en.wikipedia.org/wiki/Emmy_Noether
https://www.bbc.co.uk/programmes/m00025bw
The founder of modern Physics.
"Ecoutez et apprenez" as we say. (Listen and Learn). It's a Guage problem. Or perhaps a question of invariant theory.
In retrospect, Einstein would have preferred that name over General Relativity. 🙂
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I looked into the subtleties surrounding energy conservation in general relativity in order to put some flesh on the subject.
Underlying energy conservation is the notion that physical properties and laws don’t evolve with time.
That may be true on Earth.
However the distance between any two cosmic objects that aren’t gravitationally bound together does evolve with time.
That implies that energy is no longer conserved in an expanding Universe!
Enter Emmy Noether and her work on symmetry and conserved quantities - as described in the following link from which I have edited the above information. 😉
https://bigthink.com/starts-with-a-bang/expanding-universe-conserve-energy/
Speaking of physics related books, I read this one last year or so.
"The End of Everything" popular science book on several ways the Universe could suddenly end. Thrilling!
https://www.astrokatie.com/book
"The End of Everything" popular science book on several ways the Universe could suddenly end. Thrilling!
https://www.astrokatie.com/book
"[Katie] Mack acknowledges that many of these concepts are hard to explain without heavy use of mathematics, and then goes on to explain them expertly with no equations whatsoever." - Leah Crane, New Scientist
Sounds right up my non-mathematical street! 😎
It seemes to me that this distance not evolving, does result in no energy change.
I'm not sure what that means, but, as a mathematician, you may be interested in the article below, which is titled "Is Energy Conserved in General Relativity?".
The article is co-written by Michael Weiss and Steve's favourite mathematical physicist, John Baez.
https://math.ucr.edu/home//baez/physics/Relativity/GR/energy_gr.html
In answer to the posed question, the article starts off with, "In special cases, yes. In general, it depends on what you mean by "energy", and what you mean by "conserved".
As mentioned in both the Big Think article (to which I linked above) and the John Baez article, energy will be conserved in a Schwarzschild spacetime around a massive object, where the object is spherically symmetrical, uncharged, and "alone in the universe".
However, if the universe is uniformly filled with matter and energy, then the spacetime that describes it isn’t Schwarzschild anymore, making it difficult to establish whether energy is conserved in a more complex spacetime (FLRW spacetime) which must either expand or contract with time.
I can just about grasp the difficulties of answering the question, but obviously the mathematics in the John Baez article is well beyond me!
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A few thoughts:
We have only "objects" and (their) "changes". Energy is a synonym for change. Energy is not "something" which "works ". A pure derivation from observation of relation of objects. A concept. Not a "property" "of" "objects".
Velocity, acceleration is a derivation from observation of relation of "objects". A concept. Not a "property" "of" "objects".
Also "mass" is exactly a derivation from observation of relation of objects only, but is generally understood as "property of an object". So it took decades until one of our relativity philosophers noticed that E = mc2 could be - had to be - made to a "tangible" equation by reifying the concept "mass"-)
I didn't understand that. 🙁
For Sunday morning, here is an amusing related Physics anecdote you can tell in the pub to your drinking buddies, and they will all politely laugh, I am sure.....
Paul Dirac was known for the mathematical sophistication of his ideas and for being a man of few words. On a visit to the University of Wisconsin in 1929, a local journalist came to interview him, leading to he following exchange:
"And now I want to ask you something more: They tell me that you and Einstein are the only two real sure-enough high brows and the only ones who really understand each other. I won't ask you if this is straight stufff for I know that you are too modest to admit it. But I want to know this - Do you ever run across a fellow that even you don't understand?"
"Yes."
"This will make great reading for the boys down at the office. Do you mind releasing to me who he is?"
"Weyl."
😀
https://en.wikipedia.org/wiki/Weyl_equation
Here's a Sunday morning Higgs quiz from the good folks at Fermilab and SLAC that I hope you will all pass:
https://www.symmetrymagazine.org/ar...ake-quiz-find-out?language_content_entity=und
TADA! The old noggin still works! 🙂
It was educational too!
For Sunday morning, here is an amusing related Physics anecdote you can tell in the pub to your drinking buddies, and they will all politely laugh, I am sure.....
Paul Dirac was known for the mathematical sophistication of his ideas and for being a man of few words. On a visit to the University of Wisconsin in 1929, a local journalist came to interview him, leading to he following exchange:
"And now I want to ask you something more: They tell me that you and Einstein are the only two real sure-enough high brows and the only ones who really understand each other. I won't ask you if this is straight stufff for I know that you are too modest to admit it. But I want to know this - Do you ever run across a fellow that even you don't understand?"
"Yes."
"This will make great reading for the boys down at the office. Do you mind releasing to me who he is?"
"Weyl."
😀
https://en.wikipedia.org/wiki/Weyl_equation
Here's a Sunday morning Higgs quiz from the good folks at Fermilab and SLAC that I hope you will all pass:
https://www.symmetrymagazine.org/ar...ake-quiz-find-out?language_content_entity=und
TADA! The old noggin still works! 🙂
It was educational too!
