An Apparent Contradiction in General Relativity?

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Discussion Overview

The discussion revolves around the interpretation of general relativity (GR), particularly the concept of background independence and its implications for understanding gravity and geodesics in curved spacetime. Participants explore whether the notion of objects traveling along geodesics contradicts the principle of background independence, raising questions about the nature of motion and reference frames in GR.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants argue that the concept of traveling along geodesics implies a preferred direction of motion, which contradicts the idea of frame independence in GR.
  • Others suggest that as long as the distribution of matter determines the geodesics, background independence is not violated.
  • A participant questions the necessity of references for claims made in the discussion, emphasizing the importance of supporting statements with mainstream science.
  • Some participants propose that the discussion of preferred directions may be conflated with the nature of time and space in GR.
  • One participant offers an analogy involving a curve on a piece of paper to illustrate how paths can be parametrized without requiring a preferred direction.
  • There is a suggestion that a better definition of background independence could clarify the discussion, with references provided for further reading.
  • Concerns are raised about the interpretation of background independence and whether it has been misrepresented in the original post.

Areas of Agreement / Disagreement

Participants express differing views on the implications of background independence and its relationship to geodesics and motion. There is no consensus on whether the concepts presented are contradictory, and the discussion remains unresolved.

Contextual Notes

Some participants highlight the potential for misinterpretation of terms like "background independence" and "preferred direction," indicating that definitions and assumptions may vary among contributors.

  • #31
maddog said:
In 1975 after an Astrophysics lecture, I asked the professor of my class, if the energy of a Quasar could be a galaxy with a Black Hole at its center - could that be enough energy release to create the energy speculated to be emitting from it. He thought that was ludicrous there is no way that a Black Hole could be so massive to swallow up a whole galaxy...

I would certainly agree that the professor was wrong to say that. But note carefully how you phrased your question: you didn't say "I think relativity is wrong because it doesn't agree with my new idea". You asked, in effect, "could my new idea be consistent with relativity?" And the correct answer, even in 1975, would have been "yes, it could". Nothing in GR prohibits the existence of supermassive black holes, or having them at the centers of galaxies, and this was known in 1975. The only difference then was that such black holes were not thought to be as common as we now know them to be.

maddog said:
Oh yah, in 1975 that was sure not original...

It wasn't. Misner, Thorne, and Wheeler was published in 1973, and it talks about supermassive black holes, and makes it perfectly clear that they are consistent with GR, and that they could be at the centers of galaxies, and that objects falling into them could release enormous energies in the process. Who was your Astrophysics professor? How in touch was he with the latest developments in black hole physics at that time? (I'm guessing "not very".)

maddog said:
My only understanding is if I make a conjecture (if original so be it), I want to be able to state it as it is, empirical as it is & not requiring proof, or corroboration or any nonexistent citation.

It makes a big difference how you state it. See my comments above.
 
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  • #32
As a clarification the patent review I was talking about, handled internal patents submitted by employees. It's purpose was to recommend potential candidates for due diligence in the Intellectual Property law department. Inventors would submit a brief description and come to present and defend it. Often we would find some web reference or product that already implemented the idea and squash it. Other times we would recommend it for publish so while we don't want we also don't want to be sued by someone filing it.

The chairman taught us to be very diplomatic but this was lost on some of our members who either invented everything there ever was or never invented anything but were experts in some field. It was a fun review board we got see how an idea that can't be patented could be transformed into one that could be.
 
  • #33
Suppose someone asks "Apparent nonsense in Newtonian mechanics? : Every force has an equal an opposite reaction. If this is true, then nothing can accelerate." Will he be asked for a reference, or will his understandable confusion be clarified?
 
  • #34
Please CLOSE this thread, it has veered way off course and the OP hasn't responded sine being rebuked for his lack of references.
 
  • #35
atyy said:
Suppose someone asks "Apparent nonsense in Newtonian mechanics? : Every force has an equal an opposite reaction. If this is true, then nothing can accelerate." Will he be asked for a reference, or will his understandable confusion be clarified?

If he claims that he read this somewhere then I for one would ask for a reference.
 
  • #36
jedishrfu said:
Please CLOSE this thread, it has veered way off course and the OP hasn't responded sine being rebuked for his lack of references.
OK..
 

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