Forgelord asked in Science & MathematicsPhysics · 9 years ago

# How does relativity work?

I always thought that the faster you go, the slower time travels around you, meaning you would pass it by and end up in the future. But apparently you would end up back in time? So would it not be possible to travel into the future? How does it all work in Ender's Game? Doesn't Mazer Rackham travel into the future by going at relativistic speeds?

Relevance
• 9 years ago

Time Travel into the future is possible. If Free Will exists, then time travel into the past is not possible, IF there is only one universe. But, some versions of Quantum Mechanics proposes multiple universes. Multiple universes are possible, then time travel to the past is also possible. Though any change made in the past results in living on a different timeline. (Example of the fun you can have with this: Solution to the “Grandfather Paradox,” If you go back in time it is impossible to kill your grandfather. Every time you try the gun mis-fires and you stay on a timeline where your grandfather lives. See:

http://science.howstuffworks.com/science%E2%80%A6

Two Time Machines for travel into the future:

Type 1

Build a space ship capable of near light speed. Put it into a long orbit like a comet that returns to earth every 100 years. Get in the ship and blast off. When you return you will have aged a few years and be 100 years into the earth's future.

Type 2

Build a space station in near orbit to a Black Hole. As long as you are in the space station you age very slowly. When you leave you could be 100s of years in the future.

Special and General Relativity makes either of these possible. The science is solid, the engineering will take some work.

• JBere
Lv 6
9 years ago

You don't travel into the future. A journey of seven light years at a speed of 0.99c takes a little over seven years. Inside the ship however, the same trip takes about one year because of relativity, so while the outside universe ages seven years you only age one year. To you, you're not going faster, the distance shrinks. Length compression is the flipside of time dilation.

You don't end up back in time though. Theoretically anything that travels FASTER than the speed of light would end up going backwards in time, but it's impossible to accelerate anything past the speed of light because of relativity. The mass of the object would increase, due to the same equations that give time dilation and length compression, requiring more energy to accelerate the faster the object is going. To reach lightspeed, a literally infinite amount of energy would be required.