Stephen Hawking said that the early universe expanded faster than light, how this possible if nothing can travel faster than light?
2 Answers
The answer is time changes.
Explanation:
The experiments with light are amazing. When two cars approach each other at 60 miles/hour they converge at 120 miles/hour. When two beams of light approach each other at the speed of light they converge at the speed of light not double the speed of light.
When light goes through the gravity of the sun the light bends. This is not because the light slows down. It is because in a the presence of mass and gravity time slows down. In a black hole with "infinite" gravity time comes to a complete stop.
At the speed of light time does not exist. A light beam can travel through the same single slit hole multiple times creating a diffraction pattern of light. The light itself has "exceeded " the speed of light. It can do this not by actually moving faster than the speed of light but by changing time.
Time is relative, time can change. A photon 13 billion light years away can arrive instantly on earth in the frame of reference of the photon of light. To the photon a day is the same as a thousand years and a thousand years is the same as a day.
The universe can expand faster than light.
Explanation:
Einstein's theory of relativity states that nothing can travel faster than light. It would be more accurate to state that information can't travel faster than light in our universe. Information is typically exchanged in the form of photons which travel at the speed of light.
During the inflation period in the early universe, the universe was expanding faster than the speed of light. This is in fact allowed. It was the fabric of spacetime which was expanding faster than light.
This faster than light expansion is allowed become during the expansion it was impossible for two points of spacetime to exchange information. If a photon was released at one point in spacetime towards another which was moving away faster than light, the photon would never arrive, at least until the expansion rate slowed below light speed. The photon travelling at the speed of light wouldn't be able to keep up with the rate of expansion.
So, Stephen Hawking was correct in saying that the early universe expanded faster than light.
