This time travel that I refered to is the same time travel that I touched upon in my discussions on relativity. Basically, time is relative to the person or object that measures it. This measurement almost completely relies on the speed of the person or object. Therefore, according to relativity, as a person approaches the speed of light the more time appears to freeze to onlookers watching the person. For the person, however, time is at a normal pace and the person views the onlookers at going extremely fast. Although it is technically impossible for an object to hit the speed of light, if it were possible then time would appear to absolutly freeze to the onlookers. To illustrate, if a spaceship was able to attain the speed of light and be visible from earth, people on earth would see this spaceship is if it was at rest.
So time travel is possible, but its more of a handicap then good to astronauts. To understand why you would have to understand the dimentions of our galaxy. Pretend we could shrink the Earth so small that it’s size would be diminished to the size of a marble. Place this marble on the ground and count off four inches. This is where the moon resides in relation to the marble sized Earth. Now keep in mind how long the trip was for us to send men on the moon. Neglecting the time taken to build the rocketship (and keep in mind the speeds in which they traveled). Now walk 3 miles away from this location. What’s wrong? Can you not see Earth anymore? if you can’t you are doing the correct thing because three miles is a long way. But this is the distance that Pluto sits at. This is the last known planet in our solar system if you even count it as a planet because it is just the largest rock in a belt of asteroids. There is nothing presently here, so there would be no reason to reside here unless it was used as a space dock where spaceships used the elements as a fuel (Low gravity is a plus as well). Now lets see, we got a marble at zero, moon at four inches and Pluto at 3 miles… so the question is how far away is the closest solar system Alpha Centuri (4.3 light years in reality or 25,000,000,000,000 miles)? Put on your tennis shoes for this one. The closest solar system in our tiny model would be the equivalent as a complete trip around the planet. Feel insignificant? You should, After all when we look into the sky at this star all we see is a four year old photograph .
So at these great distances it would be extremely unrealistic to travel at speeds that are measured at anything but at lightspeed. This is not the problem because we have designed plans for a spaceship that could travel exactly at those speeds, but these super spaceshuttles ran basically on Nuclear weapons (which is now illegal [worldwide treaty] to shoot off into space because of the fact that 10% of unmanned rockets fail which would produce a nuclear blast in the atmosphere [not good!]). The true problem in travel to other solar systems is relativity. By the time the Astronauts returned from alpha centuri relatively un-aged, the world could have passed thousands of years here on Earth. Think of it, the fact that we even sent astronauts could be forgotten. Then there is the problem that the astronauts would not know anyone. Maybe the computers are so outdated that the data is untransferable. The idea I’m getting at here is so much could happen in thousands of years. On top of all this I’m ignoring the problems of space dementia, bone loss due to the lack of gravity, spare parts for the ship, food, waste, mechanical problems, computer problems and cost (and since we’re talking about time travel we’ll leave it to that)
So how have scientists decided to solve this problem? Here comes a huge headache for the faint hearted. Time travel back in time by exceeding the speed of light. What? Past the speed of light! I know what you are thinking… I just spent half an hour learning that the speed of light was the universal speed limit enforced by spacetime. It still is, but there might be a trick of hitching a ride on something that doesn’t quite follow spacetime rules. The answer to this is what scientists call a wormhole.
Think of this concept as the following example. Imagine you need to traverse the super wavy Lombard street in San Francisco. One way is to follow the law and walk down the road following all the turns. The other way is against the law, but still doable. Construct a wire grapple 5 feet off the ground, grapple onto it and slide down. Both get to the bottom, but the wire way is fastest. On a galactic view you can beat your own light that is following the curvature of spacetime with your shortcut. So how do we construct this wormhole. The answer is all theoretical. Take two blackholes singularities and connect them together. When this happens they are supposed to hypothetically annihilate each other giving a moment when a wormhole exists, but only for a moment because they will quickly pinch off and reform their singularities. Although this theory is allowed by the theory of relativity, it would take a massively negatively reversible field to do it-which scientists have no idea how to do it.
There is one more theory as well, but this one is even more confusing. You enter the very center of a large gas planet like Jupiter without bursting into flames (no gravity in the center because all points of the planet attract you which cancels them out). Then you collapse the planet to near black hole limit around you in a perfectly round shell. Then because of the warping and fall of light into the black hole you will have a time machine. The problem is that a planet the mass of Jupiter would not give any more space in the center, while still working, then ten feet. Implausible? Yes. Possible?