Travel to the past is probably impossible. But are there ways to time-travel into the future?
Of course, we are all time travelers, since we are swept along in the stream of time at a rate of one hour per hour from the past to the future.
However, the current, like a river, runs at various rates in different areas. Science, as we know it, offers us a variety of ways for accelerating into the future. Here’s a summary of what’s going on.
1. Time travel via speed
Going extremely quickly is the simplest and most practical technique to time travel into the remote future.
When traveling at speeds near the speed of light, time slows down for you in relation to the outside world, according to Einstein’s theory of special relativity.
This isn’t simply a guess or a thought experiment; it’s been proven. Physicists have shown that a flying clock ticks slower due to its speed using dual atomic clocks (one flown in a jet aircraft and the other stationary on Earth).
In the case of airplanes, the impact is negligible. However, if you were aboard a spaceship traveling at 90% of the speed of light, time would move roughly 2.6 times slower than it would on Earth.
The more you get closer to the speed of light, the slower time travels.
2. Time travel via gravity
The next method of time travel is also inspired by Einstein. The stronger the gravity you feel, the slower time flows, according to his general relativity theory.
The strength of gravity rises as you approach closer to the Earth’s center, for example. Your feet move at a slow rate than your mind.
This impact has also been measured. In 2010, scientists at the US National Institute of Standards and Technology (NIST) observed the variation in ticking rates of two atomic clocks positioned 33 cm apart on shelves. Because it has a somewhat greater gravity, the lower one ticked a little slower.
To travel far to the future, all we need is a location of incredibly intense gravity, such as a black hole The closer you get to the event horizon, the slower time flows – but it’s a dangerous business because once you cross the event horizon, you’re trapped.
Assuming you had the technology to travel the long distances required to reach a black hole (the closest is roughly 3,000 light years away), the time dilation caused by travel would be considerably higher than the time dilation caused by orbiting the black hole.
(According to Kip Thorne, the movie’s scientific advisor, the scenario shown in Interstellar, when one hour on a planet near a black hole is the equivalent of seven years on Earth, is so severe that it is impossible in our Universe.)
Perhaps the most astounding fact is that GPS systems must account for time dilation effects (due to both the satellites’ speed and the gravity they experience) in order to function. Your phone’s GPS capabilities would be unable to determine your location on Earth to within a few kilometers without these adjustments.