Speed of light questions

[dustin_archibald]

A friend of mine recently told me that most people misunderstand Einstein's Relativity. He said:

• Matter cannot reach the speed of light or surpass it.
• Light can only travel the speed of light, not faster or slower.
• Tachyons can only travel faster than the speed of light.

Is this right?

[AntonioLao]

matter in the form of energy waves can travel at light speed. Relative to the aether (vacuum), the speed of light is a constant.

[dustin_archibald]

What about tachyons? Did Einstein actually refer to them or was this found out after?

[AntonioLao]

for tachyon, please see the following website. My guess is that Einstein probably was aware of this concept since Sommerfeld was his comtemporary.

http://en.wikipedia.org/wiki/Tachyon

[dustin_archibald]

Thanks for your help.

[gs_cmans]

Dont confuse with the Quantum Electro dynamics model of Feyman in which he says the probability of light to travel above the speed of light(c). it is a different concept.