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There were many physicists who have tried to prove that time travel to the past is possible. The first of these was proposed by Kurt Gödel in 1949, a solution known as the Gödel metric. However, it was later shown that his model doesn't match the behavior of our Universe.

Another one is the concept of wormholes, introduce by the American theoretical physicist John Wheeler in 1957. A wormhole is a hypothetical topological feature of spacetime fabric that is essentially a 'shortcut' through space and time. A wormhole has at least two mouths which are connected to a single throat. While there is no observational evidence for wormholes, wormholes are known to be valid solutions in general relativity.

Another famous approach involves a dense spinning cylinder usually referred to as a Tipler cylinder, which is also a solution to Einstein's Genera Relativity discovered by Willem Jacob van Stockum in 1936 and Kornel Lanczos in 1924, but not recognized as allowing closed timelike curves until analyzed by Frank Tipler in 1974. If a cylinder is long, and dense, and spins fast enough about its long axis, then a spaceship flying around the cylinder on a spiral path could travel back in time (or forward, depending on the direction of its spiral). However, the density and speed required is so great that ordinary matter is not strong enough to construct it. A similar device might be built from a cosmic string (from Superstring Theory), but none are known to exist, and it does not seem to be possible to create a new cosmic string.

Physicist Robert Forward noted that a naïve application of general relativity to quantum mechanics suggests another way to build a time machine. A heavy atomic nucleus in a strong magnetic field would elongate into a cylinder, whose density and "spin" are enough to build a time machine. Gamma rays projected at it might allow information (but not matter) to be sent back in time. However, until we have a single theory combining General Relativity and Quantum Mechanics, we will have no idea whether such speculations are truly possible, or are just sheer nonsense.

There have been numerous famous scientists who tried to "prove" time travel.

Basically the theories that hold some (theoretical) currency are this:

1. Faster than light travel.

To understand this one first you need to be familiar with the idea that the "speed" of time isn't a constant. It's relative to your own speed. The classic example is this: Two twins. One goes into space and travels - according to the first twin - at very near the speed for light for about 3 years. When he gets back to earth, for him very little time has elapsed and for the twin who remained on earth a full 3 years have elapsed. I am not going to get into why that is as that would be a very large tangent but the essential idea is that the faster you are travelling, the slower time moves.

In fact, if you are travelling at the speed of light time stands still.

Now, what would happen if you went faster than light? Would time go backwards? The answer is hazy and somewhat moot since faster than light travel is generally considered to be a big cosmic no-no.

The second theory which some subscribe to - and popularised by hollywood is worm holes. Basically two gaps in the "Fabric" of space. These holes are essentially a tunnel between two disparate locations. My understanding is that wormholes which may exists would only exist for nano seconds and would be tiny. But if it were possible to make a big one and make it stable enough to exist for a reasonable period of time, then you could instantly jump from one point to another.

Some say, and I repeat that SOME say this could be a means of time travel. I don't really understand that logical jump myself but I am sure that would provide the grounds for further reading online.

This is all more science fiction that science really and what is postulated is generally only valid according to obscure mathematic principles and even then the actual physical results of what would occur are speculation.

Here are some other ideas:

Black holes. A black hole is a massive amount of matter compressed into a relatively tiny area. If a black hole isnt rotating then this amount of matter eventually compresses into a singularity. However, if a black hole is rotating then that singularity forms a ring. To jump through that ring is basically the same as jumping through a worm hole. Whats more its a permanent worm hole created by the laws of physics. Research has shown that at least some black holes appear to be rotating.

Godel, Feynman, , Dirac, and others were all intrigued with the possibility of time travel.

Unfortunately, few big name physicists are concerned with the "issue" of time travel, mostly because of the near-impossibility of its feasibility.

Contemporary physics books tend to lean towards fanciful tales of time travel to sell books, but those writers are rarely accepted physics and rarely make valuable contributions to Physics as a whole.

The mathematical proof for time travel, by the way is very simple.

Take the time dilation equation, and use a velocity greater than c

voila

Einstein physics show that if you approach the speed of light, you stay the same, but the world around you ages faster. The late Carl Sagan did a wonderful episode on "Cosmos" about this in the late 70's. Actually, when astronauts come back from a mission, their clokcs are slow about 1-2 seconds.

Einstein I'm sure was one. Read "Timeline" the very beginning of the book...at this point worm holes & black holes are probally our only current possibility of time travel....not machinery.

einstien said it wasn't possible