Is Faster Than Light Travel Possible Through Black Holes?

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Discussion Overview

The discussion revolves around the possibility of faster-than-light travel, particularly through black holes, and the implications of Einstein's theories and Newton's laws in this context. Participants explore theoretical concepts, challenge each other's reasoning, and examine the relationship between gravity, light, and speed.

Discussion Character

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

Main Points Raised

  • Some participants assert that Einstein's theory prohibits faster-than-light travel due to the increase in mass as one approaches light speed, but they question how this relates to black holes and gravity's effect on light.
  • Others argue that Newton's second law, F=ma, must be modified for high-speed applications, suggesting that the force acting on light could imply acceleration beyond light speed.
  • A humorous comment is made about a hypothetical scenario where a spaceship could reach Proxima Centauri faster than light from the perspective of the traveler, highlighting the complexities of relativistic effects.
  • One participant clarifies that in General Relativity (GR), objects in free fall do not experience force, which complicates the application of Newton's second law in this context.
  • There is a mention of a misconception regarding mass increase and black holes, with a reference to external resources for clarification.
  • Another participant reiterates the idea that as velocity approaches the speed of light, acceleration approaches zero, suggesting that objects cannot reach light speed.

Areas of Agreement / Disagreement

Participants express differing views on the implications of gravity and acceleration on light speed, with no consensus reached on the possibility of faster-than-light travel through black holes or the validity of the arguments presented.

Contextual Notes

Some statements rely on interpretations of relativistic physics and may not account for all assumptions or definitions involved in the discussion. The application of Newton's laws in relativistic contexts remains a point of contention.

kogaht
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I know Einstein said it is impossible to travel faster than speed of light as the mass would get infinitely large. But if black holes exist and even a beam of light would be pulled back by gravity. Then Newton's 2nd law of motion, F=ma suggest faster than speed of light is possible.

can somebody explain what I am thinking wrong.

thanks.
 
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You didn't give a full statement of your reasoning. In any case, 'F = ma' must be modified for application at high speeds.
 
On the other hand if a spaceship were to travel to Proxima Centauri from Earth at over 70% of the speed of light (from the Earth's perspective), he would reach Proxima Centauri in less than 4.3 years by his own clock, obviously faster than the speed of light.

(just kidding)
 
Doc Al said:
You didn't give a full statement of your reasoning. In any case, 'F = ma' must be modified for application at high speeds.

Say light can be sucked by black holes then there must be a force to do so. Since there is a force acting to the light, then the light must be accelerating. So the speed of light plus the extra velocity gained by accelerating = faster than speed of light.

no?
 
In GR, there's no force acting on an object in free fall. F=ma still makes sense, but the a is a measure of the deviation from geodesic (free-fall) motion.
 
kogaht said:
I know Einstein said it is impossible to travel faster than speed of light as the mass would get infinitely large. But if black holes exist and even a beam of light would be pulled back by gravity.
Are you suggesting the idea that since "mass increases" as you approach the speed of light, then objects will turn into black holes before they can reach the speed of light? If so this is a misconception, see this entry from the Usenet Physics FAQ along with pervect's post #9 on this thread.
 
kogaht said:
I know Einstein said it is impossible to travel faster than speed of light as the mass would get infinitely large. But if black holes exist and even a beam of light would be pulled back by gravity. Then Newton's 2nd law of motion, F=ma suggest faster than speed of light is possible.
can somebody explain what I am thinking wrong.

thanks.

The second law is a microcosm of SR. As v [itex]\Rightarrow[/itex] c, a gets asymptotically smaller to zero and is at "just before" zero "just before" v = c so an object is never "bumped up" to the speed of light.
 

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