Final chapter: Possability of Time Travel

Is time travel possible? Can we actually move backwards or forwards to different points on time? It is currently unknown whether the laws of physics will allow time travel to pass. In theory, particularly the multiverse theory, it is believed to be possible.

One man, a University of Connecticut professor Ronald Mallett is challenging this notion by trying to send elementary particles back into time using a laser. His project has received criticism within the physics community, but he nonetheless continues its efforts.

A central problem with time travel to the past is the violation of causality. This phenomenon is relationship between a first event and a second event where the second event is a direct consequence of the first. Thus, should an effect precede its cause, it would give rise to the possibility of temporal paradox. One of the most famous temporal paradoxes is the Grandfather Paradox. In this riddle, a boy travels back in time and kills his grandfather before his grandfather is conceived. This leaves the boy unable to return to his previous state, because in his present world, he now would not exist. Some interpretations of time travel resolve this by accepting the possibility of travel between parallel realities or universes.

I know its sort of exciting to imagine a thing like this happening. But really, according to the laws of physics- you could not travel back in time without somehow affecting the present and the future.

Time MINI mini series Part 4: Time and the "Big Bang"

Little is known about the earliest moments of the universe's history

Scientists have come to some agreement on descriptions of events that happened 10−35 seconds after the Big Bang, but generally agree that descriptions about what happened before one Planck time (5 × 10−44 seconds) after the Big Bang will likely remain pure speculation.

Stephen Hawking is perhaps the most famous cosmologist today studying time.
Upon occasion, he has stated that time actually began with the Big Bang, and that questions about what happened before the Big Bang are irrelevant.

Even if time did not begin with the Big Bang and there was another time frame before the Big Bang, no information from events then would be accessible to us, and nothing that happened then would have any effect upon the present time-frame.

Some argue that our measurable, quantified “time” concerns the elements beyond the visible universe.

Afterall, there may also be parts of the universe well beyond what can be observed in principle.

Some theories, each of which are untested hypotheses, include the Hartle-Hawking boundary condition in which the whole of space-time is finite; the Big Bang does represent the limit of time, but without the need for a singularity (one specific point where the event occurred).
Brane cosmology is another story. The word “brane” refers to a giant oscillating membrane believed to house individual universes. Brane cosmology models contend that this "inflation" of the universe is due to the movement of branes.

The pre-big bang model; the ekpyrotic model, in which the Big Bang is the result of a collision between branes; and the cyclic model, a variant of the ekpyrotic model in which collisions occur periodically between them.
Chaotic inflation occurs: in which inflation events start here and there in a random quantum-gravity foam, each leading to a bubble universe expanding from its own big bang. This my dear friends- is a segway into theories of parallel universes.