Hey /sci

hey /sci
>Travelling @ speed of Light stops Time
>Not for Sunlight.
>It needs over 8 mins to reach Earth.
How fast is Sunlight?

Other urls found in this thread:

en.wikipedia.org/wiki/Energy–momentum_relation
twitter.com/SFWRedditImages

E=MC^2
:^D

Yellow light only travels at about 0.93212c so it needs some time to get here

light doesn't have mass so it doesn't affect time

retard

That's relative to us.

If there was a reference from for light, it would travel instantly

Traveling at the speed of light stops time only if the object in question has mass, because of the equation e=mc^2.
Light can travel at the speed of light whenever it wants because it has no mass.

Wrong.

Time dilation has nothing to do with mass

Proof?

Because dynamics doesn't even enter the picture when you derive time dilation from the Lorentz transform?

>I don't know want a Lorentz transformation is

Google the time dilation equation? It involves relative velocity. No mass.

time is only "stopped" for tangible particles, not photons

You mean it's only "stopped" for particles incapable of traveling at that speed in the first place? Nice baseless conjecture.

But why?

Because light moves the same speed in all reference frames

>But why?
It is said that there are no stupid questions. "Why" is a stupid question in the way you seem to intend. The best "why" that can possibly be offered is the structure of the equations that work better than any others we've found. The laws of the universe don't need "reason".

So it is hypothetical, that means neither of us are 'technically' wrong. :^D

It's not hypothetical at all. It's a theory that has led to some of the most accurate predictions in all of science

You could say that if you have the brain of a child, but you could also say one of us is more right.

Shh, did his smiley face not tip you off?

Lol ad hominem :^D

So theory isn't theoretical? Lol okay umad? :^D

I have a legit question.

How can light __carry__ energy, if it has no mass?

E=MC^2

E=0*C^2=0

There is no reference frame for light, or anything that travels at c. There is no Lorentz transformation that takes you into a reference frame where a massive object travels at c.

>E=MC^2
>E=0*C^2=0
That is not the full equation, that's only valid at rest (zero momentum).
E^2 = (mc^2)^2 + (pc)^2, where p is momentum.
Now light has momentum (photons do, but even clasically EM waves carry momentum) that is nonzero, so E=pc.

You're formula isn't complete. This formula is for rest mass and the light certainly isn't at rest (in fact, in a vacuum it is the furthest from rest that it can possibly be). The "complete" formula is E^2=m^2c^4+p^2c^2. Photons have momentum. Note that the momentum is not classical (it isn't p=mv).

The correct formula in this case is:
[math]E^2 = (pc)^2 + (m_0 c^2)^2[/math]

en.wikipedia.org/wiki/Energy–momentum_relation

You beat me to it. The formula E=pc is known as the ultrarelativistic limit and is a good approximation when the kinetic energy of an object is significantly greater than the rest energy. Of course, for light it is trivial to show that this formula is exact.

>The formula E=pc is known as the ultrarelativistic limit and is a good approximation when the kinetic energy of an object is significantly greater than the rest energy
Indeed, especially useful and often used in high energy physics (I don't know how often I have read "neglect the electron's mass" in QFT ecercises).

Thanks a lot!