- #1

- 137

- 0

You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

- Thread starter ludi_srbin
- Start date

- #1

- 137

- 0

- #2

- 258

- 1

no, you don't. photons are massless. [tex]E=hf[/tex]

- #3

- 196

- 0

To elaborate, it only takes an infinite amount of energy for something to travel the speed of light if it has a rest mass (a mass in its own frame of reference) because relativistic mass increases as speed increases. But for something that doesn't have a rest mass (such as a photon), it has to move at the speed of light in order to even exist at all. (Or atleast, that's what the equations seem to suggest to me. I posted my reasoning behind this here: https://www.physicsforums.com/showthread.php?t=79637 and nobody told me I was wrong so I assume it was correct.)

Last edited:

- #4

Chronos

Science Advisor

Gold Member

- 11,429

- 743

Here is a link to get you started:ludi_srbin said:

Special Relativity as a Physical Theory

http://www.arxiv.org/abs/physics/0410124

And here:

http://physics.nyu.edu/hogg/sr/

- #5

- 96

- 0

εllipse said:To elaborate, it only takes an infinite amount of energy for something to travel the speed of light if it has a rest mass (a mass in its own frame of reference) because relativistic mass increases as speed increases. But for something that doesn't have a rest mass (such as a photon), it has to move at the speed of light in order to even exist at all. (Or atleast, that's what the equations seem to suggest to me. I posted my reasoning behind this here: https://www.physicsforums.com/showthread.php?t=79637 and nobody told me I was wrong so I assume it was correct.)

I think modern interpretation is that mass doesn't change (it's the same in all inertial systems), but energy does according to formula:

[tex]E = \frac{mc^2}{\sqrt{1-(v/c)^2}}[/tex].

So mass is the same in the eyes of every intertial observer (the term "invariant" is commonly used).

Share:

- Replies
- 18

- Views
- 1K