# Time Travel Possibilities

Time, being the fourth dimension of our universe, is interconnected with the space (three dimensions) in a way that it cannot exist without space, and space cannot exist without time. This kind of relationship between time and space is called the spacetime continuum, which means that any event that occurs in the universe has to involve both space and time.

According to Einstein's theory of relativity, time gets slower as we approach the speed of the light, and apparently that means time travel is possible, but the problem is if any object tries to approach the speed of the light, its mass gets increased (E=mC^2) for the apparent reason that we try to provide more and more energy to increase the objects speed and as E(energy) directly proportional to m (mass), mass gets increased and that reaches infinite as the object reaches the speed of the light, which is practically impossible. so we can't travel in time, this is what some our physicists say.

### Its possible.. they say

Anyways, Theories are never been agreed so easily, there is always an other side and this is how it goes: there are some physicists who believe traveling faster than light (FTL) is possible and they say.

### Quantum tunneling

Quantum Tunneling is the quantum mechanical effect that permits a particle to pass through a barrier when it does not have enough energy to do so classically. You can do a calculation of the time it takes a particle to tunnel through such a barrier. The answer you get can come out less than the time it takes light to cover the distance at speed c. Does this provide a means of FTL communication?

Ref: T. E. Hartman, J. Appl. Phys. 33, 3427 (1962).

### Casimir Effect

The Casimir Effect describes the fact that a very small but measurable force exists between two uncharged conducting plates when they are very close together. It is due to the existence of vacuum energy. A surprising calculation by Scharnhorst suggests that photons travelling across the gap between the plates in the Casimir Effect must go faster than light by a very very small amount (at best 1 part in 1024 for a 1 nano meter gap). It has been suggested that in certain cosmological situations, such as in the vicinity of cosmic strings if they exist, the effect could be much more pronounced. However, further theoretical investigations have shown that, once again, there is no possibility of FTL communication using this effect.

### Virtual Photons

In quantum field theory forces are mediated by "virtual particles". The Heisenberg Uncertainty Principle allows these virtual particles to move faster than light

### Cherenkov Effect

One way to go faster than light is to make the light slow down! Light in vacuum travels at a speed that is an universal constant , but in a dense medium such as water or glass, light slows down to c/n where n is the refractive index of the medium (1.0003 for air, 1.4 for water) and c velocity of light. It is certainly possible for particles to travel through air or water at faster than the speed of light in the medium, and Cherenkov radiation is produced as a result.

Read more:  Time Travel Possibilities in Deep Study