Time travel to the future is possible within the laws of physics. Travelling to the past seem less likely to be achieved according to physicists. But J Richard Gott III, a professor of astrophysical sciences at Princeton University, explores the physics of time travel and suggests that time travel to the past might be possible. He also promoted his theory for how the Universe began - through a time loop that allowed it to create itself - and revealed how the Copernican Principle could be used to predict the likelihood of events as diverse as the fall of the Berlin Wall to the extinction of the human race.
In his theory of past time travel Richard Gott sais that can visit the past but you cannot change it.
If you want to see the past rather than visit it this is already possible. Because of the finite speed of light, when we look at a star 10 light years away we are seeing what it looks like 10 years ago because it takes the light and the image that long to travel back to us. Even looking in the mirror is seeing the past also due to the speed of light. If you are 5 feet in front of your mirror the image you receive is of yourself 10 nanoseconds ago.
To visit the past means traveling faster than the speed of light and according to Einstein's theory of special relativity that is not possible.
Gott sustains his own theory of "cosmic strings" and according to him the law of physics can be overstepped using Einstein's theory of curved space-time.
If you want to see the past rather than visit it this is already possible. Because of the finite speed of light, when we look at a star 10 light years away we are seeing what it looks like 10 years ago because it takes the light and the image that long to travel back to us. Even looking in the mirror is seeing the past also due to the speed of light. If you are 5 feet in front of your mirror the image you receive is of yourself 10 nanoseconds ago.
To visit the past means traveling faster than the speed of light and according to Einstein's theory of special relativity that is not possible.
Gott sustains his own theory of "cosmic strings" and according to him the law of physics can be overstepped using Einstein's theory of curved space-time.
Time travel to the future, let's say to the Earth 1,000 years from now could be possible if a person gets in a spaceship, travels to a star a bit less than 500 light years away and returns traveling both ways at 99.995% of the speed of light. When arriving to Earth that person would be 1,000 years older but he would have only aged 10 years. This is possible because time passes more slowly when traveling at such speeds. But there are huge technical barriers to overcome in achieving this scientific possibility. The Russian cosmonaut Sergei Avdeyev who was in orbit a total of 748 days during three space flights, is about 1/50th of a second younger than he would be if he hadn't gone on those trips so he is really a time traveler. When he arrived home, he found the earth 1/50th of a second to the future of where he expected to find it.
Predicting the Future
Gott has discovered a way of predicting how long something you are observing is likely to last. The idea is based on the Copernican Principle - the idea that your location in time and place is not special. Gott discovered this idea in 1969 whilst looking at the Berlin Wall, which he correctly predicted (with 50% confidence) would have a future longevity of between 2-2/3 years and 24 years. If you observe something at a non-special or random time there is a 50% chance that it is in the middle two quarters of its period of existence. At one extreme the future will be three times as long as the past at the other extreme the future is one third as long as the past. There is a 50% chance you lie between these extremes so the future is between one third and 3 times as long as the past. Gott has refined this theory to ensure that the prediction is 95% reliable, the scientific standard, and has used it to predict everything from the future longevity of the human race (5,100 years to 7.8 million years) to the future longevity of the New York Times (3.8 years to 5,811 years).
