# Why is light speed the limit? [duplicate]

Why is the light speed a limit? Why can't anything go faster than light? Not even a single atom?

## marked as duplicate by Dilaton, Brandon Enright, Frédéric Grosshans, jinawee, akhmeteliFeb 14 '14 at 18:04

• possible duplicate of Travelling faster than the speed of light – Danu Feb 14 '14 at 17:04
• This question has been asked before: Please browse around this forum to find related questions and answers. – Danu Feb 14 '14 at 17:05

There's no answer to this "Why". This is what we observe in nature. Nothing* can travel faster than light.

*Note: Denizens of the Quantum World like atom may not be agree with this. For example, information of quantum states of two entangled entities are shared between them faster than light. It has been tested with polarized light beams. Understand it this way: Suppose, two electrons are in Quantum Entanglement and both are in Quantum Superposition possessing up & down spin at the same time. You separate both electron to the opposite edge of the Galaxy and break the superposition of one electron. The other electron will know about it exactly at the same time faster than light. If one electron is ended up with Up Spin, Other one would start possessing Down spin instantly even if nothing's there to break the superposition.
Einstein called this faster than light Quantum interaction "Spooky action at a distance."

• * information of quantum states of two entangled entities are shared between them faster than light. * This, of course, is 100% false . – WillO Feb 14 '14 at 19:39
• @WillO Einstein called it "Spooky action at a distance." Search this phrase. Or, see: livescience.com/27920-quantum-action-faster-than-light.html – Schrödinger's Cat Feb 14 '14 at 21:01
• @iani, Sachin Shekhar: "There's no answer to this "Why" [Why is light speed the limit?]. This is what we observe in nature" -- Wrong. "Speed" is a quantity to be measured, obtaining commensurate result values. They're not obtained by plainly "observing nature", but instead by applying a suitable measurement operator to (given) observational data. The answer is therefore: that's a consequence of the definition of how to measure "speed"; especially Einstein's (or at least Synge's) definition to measure "distance" between "ends" $A$, $B$ as "c/2 Pingduration_ABA" = "c/2 Pingduration_BAB". – user12262 Feb 14 '14 at 21:20
• @SachinShekhar: I am well acquainted with quantum entanglement and so-called "spooky action at a distance". You most definitely cannot exploit this phenomenon to transmit information faster than light. – WillO Feb 14 '14 at 21:22
• @user12262 What The heck... Go read meaning of Observation. And, you must know that Light Speed limit was found before the existence Relativistic Physics. It's not the consequence of measurement scale change. Maxwell's equation predict that there can't be standing electromagnetic wave. – Schrödinger's Cat Feb 14 '14 at 22:17

Because not until now that scientists discovered laws that can be applied on objects attaining even the speed of light .. actually no one knows what happens when an object attains the speed of light

• So we don't know what light is? – jinawee Feb 14 '14 at 17:39