Neutron Star at Near Light Speed

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Discussion Overview

The discussion revolves around the hypothetical scenario of a neutron star being accelerated to near the speed of light and the implications of such a scenario on its mass and potential to collapse into a black hole. Participants explore concepts related to relativistic mass, gravitational interactions at high speeds, and the nature of black holes in different inertial reference frames.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions whether a neutron star accelerated to near light speed would collapse into a black hole, expressing a personal guess that it would not.
  • Another participant asserts that, at relativistic speeds, an observer would perceive an increase in mass, but emphasizes that in their own rest frame, they remain stationary.
  • Several participants discuss the concept of relativistic mass, with one noting it is becoming less common in scholarly use and primarily relevant for discussing forces needed for further acceleration.
  • There is a query about how two bodies traveling at near light speed would interact gravitationally, with speculation that their interaction might depend on their apparent relativistic masses.
  • One participant concludes that a massive body not classified as a black hole in its own inertial frame cannot be a black hole in any frame, suggesting that gravitational interactions at relativistic speeds resemble Newtonian gravity.
  • Another participant agrees with this perspective but raises a question about its consistency with special relativity, referencing accelerated particles at CERN that do reach relativistic speeds.

Areas of Agreement / Disagreement

Participants express differing views on the implications of relativistic mass and gravitational interactions at high speeds. There is no consensus on whether a neutron star could become a black hole when accelerated to near light speed, and the discussion remains unresolved regarding the nature of gravitational interactions between relativistic bodies.

Contextual Notes

Participants highlight the complexity of gravitational interactions at relativistic speeds and the evolving understanding of relativistic mass, indicating that assumptions about mass and gravity may depend on the chosen reference frame.

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What would happen to a neutron star (on the cusp of becoming a black hole) if it were sped up to near the speed of light? Or more easily done, if I sped up to near the speed of light. Would the additional mass from the near light speed cause the neutron star to collapse in on itself and form a black hole?

I am guessing that a black hole would not form, but I am curious as to the reason why. If my guess is wrong and a black hole would form, then what would a person stationary to (and light hours away from) the black hole see? The stationary person would not detect an increase in mass to cause the collapse.

Any insight would be appreciated.
 
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You, right now as you read this, are traveling at .999999999999999c. This is enough speed to cause you to become REALLY massive in the sense that you mean. Do you feel any heavier now that you know that? The accelerated particle that I used to make that determination of your speed is in a rest frame from which you appear to be going as fast as I said, and from that IRF you "appear" very massive, again, "in the sense that you mean".

The point here is that in the rest frame of any object, it is standing still.

Does that answer your question?
 
You are talking about relativistic mass, which is a misleading concept that is rapidly disappearing from scholarly use. It is basically only useful for talking about the force necessary to further accelerate a massive body traveling at relativistic speeds.
 
Chronos said:
You are talking about relativistic mass, which is a misleading concept that is rapidly disappearing from scholarly use. It is basically only useful for talking about the force necessary to further accelerate a massive body traveling at relativistic speeds.

Interesting. I had not heard that. So, if two bodies were traveling at near the speed of light relative to one another and they interacted gravitationally, would their interaction happen according to their rest masses or to their apparent, relativistic masses?
 
I read a little on relativistic mass, so maybe I can answer my own question. From what I can gather, it is an effect of space-time itself and not the internal structure of the object itself. The neutron star would not turn into a black hole no matter how fast it went.

However, I am still unclear how two objects approaching each other at near the speed of light would interact gravitationally. Since relativistic mass is a space-time effect, I would guess that the two objects would interact as if they were more massive. But that is just a guess.
 
Correct! A massive body that is not a black hole in its own inertial reference frame is not a black hole in any inertial reference frame. Gravitational interactions between bodies traveling at relativistic speeds looks complicated, but, is not. It still looks like plain old Newtonian gravity. This, of course, is theoretical. Stars of any kind are not known to travel anywhere near relativistic velocities.
 
Chronos said:
Correct! A massive body that is not a black hole in its own inertial reference frame is not a black hole in any inertial reference frame. Gravitational interactions between bodies traveling at relativistic speeds looks complicated, but, is not. It still looks like plain old Newtonian gravity. This, of course, is theoretical. Stars of any kind are not known to travel anywhere near relativistic velocities.

Although I understand, and in fact agree w/ what I believe you mean, it does lead to the question of whether or not that way of putting it is consistent with SR. After all, according to an accelerated particle at CERN, they DO travel at relativistic speeds.
 

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