Time travel has long been a popular topic in science fiction, but can it really exist? The Daily Mail recently published an article by Professor Brian Cox arguing that travel to the future is possible. But if you get there, you can't go back.
Speaking at the British Science Festival, Cox said that time travel has already been achieved, albeit on a very small scale. He discussed the theory of relativity, saying:
Cox's theory is based on Einstein's theory of special relativity, based on two principles. First, the laws of physics do not change, even when objects move at a constant speed relative to each other. Another principle is that the speed of light is the same for everyone, no matter how they move in relation to the light source.
If two objects are moving in space and want to compare what they "see", the only way to do this is to compare how fast the objects are moving relative to each other. Cosmonaut Sergei Krikalev
To travel in time, the speed of an object must approach the speed of light. When an object approaches the speed of light, the clock slows down, but only for a moving object. Everything else is still moving in time at the same speed.
Cosmonaut Sergei Krikalev, Federal Space Agency of Russia, commander of the 11th expedition, commander of the Soyuz spacecraft.
Our cosmonaut Sergei Krikalev has spent more time in orbit than anyone else in the world - 803 days, 9 hours and 39 minutes. If you add up all the accumulated speed since the time he spent in orbit, Krikalev has indeed moved into his future by about 0.02 seconds, according to Universe Today.
Promotional video:
Time dilation (the relative time difference between, say, an astronaut in orbit and everyone else on the planet) is caused either by a difference in relative speed or gravity, each of which has its own effect over time.
The ISS-1 Expedition crew launched from Soyuz TM-31.
When an object is in space, be it a satellite or an astronaut, it is slightly farther from the planet's gravitational force, so its clock runs faster, albeit a tiny amount, than on the surface of the Earth. When an astronaut returns to Earth, he has to "go back" to the past regarding when he was in space.
However, the temporal dilatation due to speed means that the astronaut's clock will run slightly slower than all clocks on Earth, which means that the astronaut will have to go a little into the future to catch up with the clock on earth.
Earth's gravity is relatively weak and does not exert much pressure on bodies in space, so Krikalev's clock also runs a little slower when in orbit, which has moved him forward in time.
Our current technology does not allow this effect to be more pronounced than a leap into the future by thousandths of a second. We do not have the ability to accelerate objects to speeds where the effect of time dilation would be greater than the smallest fractions of a second.
All this seems complicated and rather far from what most people see in everyday reality, but think about it: Sergei Krikalev is living proof that time is not like an arrow that just flies forever in one direction. It is really relative.