Can something exceed the speed of light?

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Discussion Overview

The discussion revolves around the concept of the speed of light, its implications in physics, and whether anything can exceed this speed. Participants explore the theoretical underpinnings of light speed, the effects of constant acceleration, and the relativity of velocity in the universe.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants inquire about how the speed of light was established as 3*10^8 m/s, referencing Maxwell's equations and the wave equation.
  • It is suggested that the impossibility of exceeding the speed of light is a consequence of the postulates of relativity.
  • Questions are raised regarding the behavior of a body under constant acceleration in space and whether it could exceed the speed of light, with some arguing that its inertial mass increases with velocity, preventing it from reaching light speed.
  • Participants discuss the concept of "absolute" velocity, noting that all velocities are relative and that no speed can exceed the speed of light.
  • One participant introduces the distinction between group and phase velocity, mentioning that light can exceed these velocities in certain media but not in a vacuum.
  • There is a request for clarification on the measurement of speeds in relation to different objects, indicating a need for further exploration of reference frames.

Areas of Agreement / Disagreement

Participants express various viewpoints on the nature of light speed and its implications, with no consensus reached on the broader implications of constant acceleration or the concept of absolute velocity.

Contextual Notes

There are unresolved questions regarding the definitions of group and phase velocity, as well as the implications of constant acceleration in different reference frames.

ahmedhassan72
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How was the speed of light proved to be 3*10^8...also How it was proved that nothing can exceed the speed of light?...and what will happen if something moves under the effect of certain force with constant acceleration in space i.e the net force on it is constant and not equal zero...is that possible and will that body at certain instant exceed the speed of light ?and if so what will happen...another question, does my absolute velocity in the universe exceed the speed of light i.e I move with 100 km/h the Earth moved with x km/h and the galaxy and so on ...
Thanks for consideration
 
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ahmedhassan72 said:
How was the speed of light proved to be 3*10^8
Using Maxwell's equations & the wave equation.
ahmedhassan72 said:
...also How it was proved that nothing can exceed the speed of light?
It is a consequence of one of the postulates of relativity.
ahmedhassan72 said:
...and what will happen if something moves under the effect of certain force with constant acceleration in space i.e the net force on it is constant and not equal zero...is that possible and will that body at certain instant exceed the speed of light ?
No since the body's inertial mass increases with velocity (http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html).
 
Last edited:
ahmedhassan72 said:
How was the speed of light proved to be 3*10^8...
It was first deduced, then measured. (Given our modern understanding, it is now defined to be a certain speed.)
also How it was proved that nothing can exceed the speed of light?...
It's a consequence of relativity.
and what will happen if something moves under the effect of certain force with constant acceleration in space i.e the net force on it is constant and not equal zero...is that possible and will that body at certain instant exceed the speed of light ?and if so what will happen
While the force and acceleration will appear constant as measured by observers moving with the body, it will not appear constant to others. The speed of the body with respect to any other object will never reach light speed.
...another question, does my absolute velocity in the universe exceed the speed of light i.e I move with 100 km/h the Earth moved with x km/h and the galaxy and so on ...
There's no "absolute" velocity; all velocities are relative. No, your speed with respect to anything will be less that the speed of light.
 
We have to careful about whether we are talking about the group or the phase velocity. This is where the confusion comes in when people say they made light travel faster than the speed of light, they mean the group (or is it phase?) velocity of light through a specific medium. Nothing can travel faster than light in a vacuum, light can exceed its group (phase?) velocity in a medium like water, and give off pretty blue radiation.

I hope someone else can explain this better than me.
 
ahmedhassan72 said:
another question, does my absolute velocity in the universe exceed the speed of light i.e I move with 100 km/h the Earth moved with x km/h and the galaxy and so on ...
Thanks for consideration

What are the speeds of these objects being measured with respect to?
 

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