Is it Possible to Attain the Speed of Light by Combining Two Half-Speed Bodies?

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Discussion Overview

The discussion revolves around the possibility of attaining the speed of light by combining two objects moving at half the speed of light (0.5c) in opposite directions. Participants explore concepts from special relativity, particularly how velocities combine and the implications for measuring the speed of light.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether achieving a speed of 0.5c is possible and proposes that combining two such bodies could lead to reaching the speed of light.
  • Another participant clarifies that while 0.5c is attainable, the addition of velocities in special relativity does not follow classical rules, citing the formula w=\frac{u+v}{1+\frac{uv}{c^2}}.
  • A participant expresses uncertainty about the implications of the relativistic velocity addition formula regarding the attainability of light speed.
  • One participant asserts that if both objects are moving at speeds less than c, their combined speed will still be less than c.
  • Another participant emphasizes that all observers measure the speed of light as c, regardless of their own speed, and discusses the implications of this for the scenario presented.
  • A later reply suggests that while the relative speeds of the ships may appear to approach c, the emitted light from each ship will still be observed at speed c by all observers.

Areas of Agreement / Disagreement

Participants express disagreement regarding the possibility of reaching the speed of light through the combination of two half-speed bodies. While some acknowledge the attainability of 0.5c, there is no consensus on whether this leads to light speed.

Contextual Notes

Limitations include the dependence on the relativistic velocity addition formula and the implications of the second postulate of special relativity, which may not be fully understood by all participants.

waqarrashid33
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Every one know that the speed of light "c" is unattainable but IS half the speed of life is attainable?
i.e 1/2(c)
If we get two bodies of 1/2(c) speed then by moving these bodies in opposite direction the spees of light is attainable?
Is it possible?
 
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A speed of 0.5c is attainable, but velocities don't add up like that in special relativity. Instead of w=u+v, the rule is

[tex]w=\frac{u+v}{1+\frac{uv}{c^2}}[/tex]

With u=-0.5c and v=0.5c, you get w=c/(1+0.25)=0.8c.
 
I don't know about the details of relativity but know about it,s results.
Is from this equation the velocity of light is attainable or not by the motion of two bodies having speed less than C
 
It's not. If u<c and v<c, then w<c.
 
Since this is the Relativity section, think of the situation in terms of Special Relativity.
The 2nd postulate says that all observers measure the speed of light to be the same c.
So it doesn't matter to me how 'fast' any other object is traveling, I always measure c as c. I could accelerate for a long time, making me go a lot faster than other objects, doesn't change anything - we will each continue to measure c.
A consequence of this idea is that, as stated above, the (relative) speeds of individual moving objects does not add algebraically.
Ron
 
If we get two bodies of 1/2(c) speed then by moving these bodies in opposite direction the spees of light is attainable?
Is it possible?

yes. Fredriks answer is precisely correct as observed from either u or v,

but if these are the speeds of spaceships relative to earth, an observer will see the ships moving apart at speed c...but if each ship emitted light, the light from each would be observed at speed c among all observers...
 

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