# Tagged Questions

The speed of light is a fundamental universal constant that marks the maximum speed at which energy and information can propagate. Its value is $299792458\frac{\mathrm{m}}{\mathrm{s}}$.

69 views

### Will light continue traveling after the source has stopped producing light? [closed]

Will light continue traveling after the source has stopped producing light?
104 views

### How can travelling at light speed affect light itself? [duplicate]

~Hypothetical Scenario: Your driving in a car (with the headlights on high beam) and you gradually get faster until you reach the speed of light. Raised Assumptions: You can see in and out of the ...
82 views

### Observing light speed

Consider an observer B is moving with speed $0.8c$ relative to another observer A in standard-configuration (I think it is called that in english: that the system B is only moving along the $x$-axis ...
183 views

### Why is the speed of light in vacuum what it is?

Three-pronged question on the speed of light. One: simply, do we know why the speed of light in a vacuum is what it is and why nothing is allowed to go faster? Two: if we knew why the speed of ...
38 views

### Dispersion for a highly energetic electron

The dispersion relation can be expressed as: $$w=\frac{\hbar k^2}{2m}$$ The energy of a free particle is: $$E=\sqrt{p^2c^2+m^2c^4}$$ For a highly energetic electron we have $E\approx pc.$ The ...
673 views

### Why is light in vacuum so slow? [duplicate]

Accepting the speed of light in vacuum and infinite mass and all that, I wonder why light does not have infinite speed? I know light does not have rest mass, but people use the term infinite mass ...
102 views

### Equal and opposite reaction at light speed

My knowledge of physics is very limited. And this question is only really to help me put to rest a question i have had for some time. I would like the answer to be a simple one as i am not really in ...
182 views

### What experiments have been done that confirm $E=mc^2$?

What experiments have been done that confirm $E=mc^2$? Are there experimental results that contradict $E=mc^2$? Or are experimental results consistently showing this famous formula to be true?
62 views

### Speed of light violation?

While reading this article Discovery of the companions of millisecond pulsars, it mentions a pulsar rotating multiple times a second, and I was wondering if this doesn't exceed the speed of light?
143 views

### Can a black hole move at speed of light?

Black hole comes in all sizes ranging from microscopic black hole on a quantum scale to supermassive black hole that resides in the center of probably every galaxy. Photon have no rest mass hence they ...