[Special Relativity] Test Particle Inside the Sun's Gravitational Field

In summary, the conversation discusses an attempted solution for a physics problem involving finding the equation for gamma as a function of r using Newtonian gravity applied to special relativity. The solution is based on the work of another user on StackExchange, but it is unclear if the solution is correct or not. The conversation also mentions the incompatibility of special relativity and Newtonian gravity, suggesting the use of General Relativity. However, the class where the problem was given is an SR class and the correct equation is not mentioned in Sean Carroll's lecture notes. The conversation concludes with a suggestion to ask the instructor for clarification and the reminder that mathematically, there is nothing stopping one from attempting to solve the problem.
  • #36
I'd say the OP has to live with the course he's on. Any moral dilemma rests with the university. The mathematics is almost identical to Newtonian gravitation, so it's not wasted effort in that sense.

I don't see it's any worse than teaching the Bohr atom. There are times when one, as a mere student, has to just get on with it!
 
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  • #37
PeroK said:
I'd say the OP has to live with the course he's on. Any moral dilemma rests with the university. The mathematics is almost identical to Newtonian gravitation, so it's not wasted effort in that sense.
It is not a moral dilemma for the university or the professor if they are not aware of the issue. I do not know the professor so I do not know if this is a case of misplaced ”lies to children” or an actual misconception on the professor’s part.

PeroK said:
I don't see it's any worse than teaching the Bohr atom. There are times when one has to just get on with it!
The Bohr model is not fundamentally incompatible with the theory it is being applied to. It is a model on its own that has been surpassed. You are not going to use the Bohr model as a part of a QFT problem. Here, Newtonian gravitation is fundamentally incompatible with SR and the problem is trying to force it in with hammer and nail.
 
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  • #38
PeroK said:
I don't see it's any worse than teaching the Bohr atom. There are times when one, as a mere student, has to just get on with it!
The Bohr atom is an inaccurate model and puts quantisation in by hand, but it's not self-contradictory. Using Newtonian gravity with its infinite propagation speed in a special relativistic framework is self-contradictory. It isn't even, so far as I know, a historical model in the sense that we occasionally discuss light as a wave in a medium with Fitzgerald contraction (arguably contradictory, given what we know now). That's my philosophical problem with this question.

Agree with @Orodruin that if there's some way @Athenian can (safely!) direct the prof here that would be good. Are the problem sheets online?
 
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  • #39
Thank you all for your comments and the discussion over here.
However, considering that I am an exchange student in a foreign country and university, I find it quite difficult to approach the professor about this problem. I'm sure if I discuss the topic with the professor in an incredibly cautious and tactful manner, my argument may be accepted more or less well. However, I highly doubt that it will solve anything.

If anything, I think it would be best I approach the professor regarding the issue once the semester ends in give or take a week. Then, the grade will be finalized and I will not be taking any unnecessary risk.

In short, this is my opinion as I have very little idea of how the professor will react.
Regardless, thank you all for your thoughts and contributions on the matter!
 
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  • #40
Ibix said:
Are the problem sheets online?

Apologies for forgetting to answer this question. But, no, I highly doubt (and ultimately, do not believe) the problem sheets are online. However, thus far, I have posted 5 out of 8 of the questions here on the forum - all titled "Test Particle Inside the Sun's Gravitational Field".
 
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  • #41
Athenian said:
Apologies for forgetting to answer this question. But, no, I highly doubt (and ultimately, do not believe) the problem sheets are online. However, thus far, I have posted 5 out of 8 of the questions here on the forum - all titled "Test Particle Inside the Sun's Gravitational Field".

This problem intrigues me. First, it's a static gravitational field, so infinite propagation speed isn't an issue. Second, there's nothing wrong with investigating this and seeing what comes out. There is orbital precession, for example. I've looked up all the data for Mercury and estimated its precession based on this "Newtonian/SR" hybrid theory. I don't know if this is where your Prof is heading. If so, I see nothing invalid in showing that these calculations do not solve the gravity/SR conundrum.

The interesting thing I learned is that the precession of Mercury is dominated by a factor based on the gravitational pull of other planets. The GR correction is only about 10% of this. (How did the physicists of the past do all this without computers?)

Anyway, as long as you know you are only investigating a debunked hybrid theory, perhaps you can learn quite a lot about physics from this exercise.
 
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  • #42
PeroK said:
This problem intrigues me. First, it's a static gravitational field, so infinite propagation speed isn't an issue. Second, there's nothing wrong with investigating this and seeing what comes out. There is orbital precession, for example. I've looked up all the data for Mercury and estimated its precession based on this "Newtonian/SR" hybrid theory. I don't know if this is where your Prof is heading. If so, I see nothing invalid in showing that these calculations do not solve the gravity/SR conundrum.

The interesting thing I learned is that the precession of Mercury is dominated by a factor based on the gravitational pull of other planets. The GR correction is only about 10% of this. (How did the physicists of the past do all this without computers?)

Anyway, as long as you know you are only investigating a debunked hybrid theory, perhaps you can learn quite a lot about physics from this exercise.

Interesting! Thank you for the explanation. While I have no idea where my professor is heading with these questions, I suppose I'll find out by the end of all this.
But, perhaps it's just me, I do find it quite odd that students are tasked to "investigate a debunked hybrid theory" in a purely SR class (of course, with Newtonian background to reinforce understanding). Regardless, by the end of the day, I hope I learn something valuable.
 

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