Introduction
When the phrase "time travel" mentioned we automatically resort to the futuristic devices, time machines and Back to the Future. But in true fact, time travel is not only possible is has happen before. Before we understand time travel, we must understand the universe, or what we know about the universe right now.
Spacetime Fabric?
Right now we believe that space is made up of a fabric called spacetime. Spacetime is a 4 dimensional object which contains all our known 3D objects but including another dimension, called time. If we lived in that dimension we would be able to navigate time just like left and right. As spacetime is like a fabric the only thing that bends spacetime is gravity. A star or planet's gravity can bend the spacetime fabric. As we do not live on the 4th dimension the bending of spacetime changes the time we feel.
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Important!
Another important concept to understand is that time works differently for everyone and the passing of time refers to our age, not our ageing.
We Already Know About Time Travel (you are been kept in the dark!!!)
We know about time travel... One of the most important cases of time travel we use nearly every day is GPS navigation. GPS satellites orbit the Earth to help you navigate around the globe or your local neighbourhood. To keep all the data in sync the satellites need an atomic clock on board. It is an extremely exact clock that calculates time by measuring the amount of times that a specific atom vibrates, hundreds of millions of time per minute. The atomic clock that resides in space automatically goes into the future by a few nanoseconds every day. So the atomic clocks on the ground are behind the atomic clocks in space and this needs to be taken into account every day because not doing so will cause problems to the satellites. Now that we understand gravity influences time, because the satellites are further away from the Earth's gravitational pull, time has to travel less, along the fabric of spacetime than if it that to travel the whole bend of the Earth's gravity. Let talk about astronauts. The astronaut that has stayed in space the longest, 800 days, has traveled into the future by 0.2 seconds.
Now let's get to the exciting part of time travel. If somehow, in the far future, we were able to travel the 90% the speed of light, and someone traveled for 7 years, away from Earth at the speed of light, and then turned back and somehow intercepted Earth, in the 14 years that would have passed for the person on board, on Earth 2800 years would have past. This is because of two things. The speed you are traveling and the zero gravity you are facing. In Earth years, you would be 2800 years old, but you would have only aged 14 years. The technical term for this is time dilation. If you don't call that time travel I am not sure what I would... |