10 votes
Accepted

Why can't any object gain the speed of light?

You're using the additivity of velocities that is valid only for very low velocities, in Newtonian mechanics. That's not how things work for high velocities, where special relativity applies: $$v_x=\...
user avatar
  • 2,256
6 votes
Accepted

Example of information travelling faster than the speed of light?

Therefore, we can use the law of Biot-Savart No, you cannot use the Biot Savart law in this situation. The Biot Savart law is derived from the magnetostatic assumption. That is, the assumption that $...
user avatar
  • 65.8k
4 votes

Can one record a speed faster than $c$?

To support what the earlier answers are saying, consider this "position-vs-time diagram" (spacetime diagram) with time running upwards. To make the arithmetic easier, I'll use $v=(3/5)c=(0.6)...
user avatar
  • 8,677
3 votes
Accepted

Does a smooth world sheet imply strings moving faster than light?

TL;DR: The string is not moving faster than light. A 2D tangent plane $T_pN$ of a regular/generic point $p$ of the 2D string world sheet $N:=X(\Sigma) \subseteq M$ imbedded into a Lorentzian target ...
user avatar
  • 170k
1 vote

If galaxies beyond the cosmological event horizon move faster than light is then that motion a combination of their KE and space expansion?

The motion is primarily due to expansion. The KE is almost always irrelevant. Imagine two objects with equal mass in a common circular orbit about their midpoint M. Assume that M is exactly at the ...
user avatar
  • 450

Only top scored, non community-wiki answers of a minimum length are eligible