Accelerating to the speed of light

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Discussion Overview

The discussion revolves around the concept of approaching the speed of light, particularly from different frames of reference in the context of special relativity. Participants explore the implications of relativistic effects on mass, time, and length as perceived by observers in different states of motion.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that as an object approaches the speed of light, its mass approaches infinity, making it impossible to reach that speed from an external observer's perspective.
  • Another participant clarifies that in the frame of reference of the person moving towards the speed of light, their speed is perceived as 0, indicating that they do not experience any unusual effects on mass, time, or length.
  • A later reply emphasizes the importance of understanding that different observers have different frames of reference, leading to varying perceptions of speed, time, and length, which is a key aspect of special relativity.
  • It is noted that the constancy of the speed of light is a fundamental principle that remains fixed for all observers, contrasting with the variability of space and time measurements.

Areas of Agreement / Disagreement

Participants generally agree on the significance of different frames of reference in special relativity, but there is some contention regarding the implications of mass and speed as one approaches the speed of light.

Contextual Notes

Participants express varying levels of understanding regarding the implications of special relativity, and there are unresolved questions about the nature of mass and its relationship to speed in different frames of reference.

Shark 774
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Hey, I understand why if you watch someone they can never accelerate to the speed of light: their mass approaches infinity so the necessary impulse reaches infinity. But what about in the frame of reference of the person approaching the speed of light. They notice nothing unusual about their mass/time/length so clearly the previous explanation doesn't fit. Maybe my first explanation isn't the best way to explain it? Need some help please!

Cheers -
 
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?? In "the frame of reference of the person approaching the speed of light", nothing changes because their speed in that frame of reference is 0. The speed of any person or object in is own frame of reference is 0- nowhere near the speed of light!

You can only "approach the speed of light" (or be moving at all) in the frame of reference of some other person.
 
HallsofIvy said:
?? In "the frame of reference of the approaching the speed of light", nothing changes because their speed in that frame of reference is 0!

You can only "approach the speed of light" (or be moving at all) in the frame of reference of some other person.

Ah ok, so my question was a totally moot point! Thanks for that.
 
But your question does point out an important aspect of special relativity: everybody's frame of reference is in general different and that is something that was not clearly understood before Einstein. Not only do different observers see different speeds, but time passes at different rates for each and each may measure different lengths as well...

The underlying principle is that it is NOT space and time that are fixed as we all might think from everyday [low speed] observations, these in fact vary with observer speed, but it is the speed of light that IS fixed, that is, the same for all observers.
 

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