Shrug asked in Science & MathematicsPhysics · 7 years ago

# Does Einstein's theory of relativity say time travel is possible?

Einstein's Theory of Relativity states that time is relative, so would that mean it is possible for an astronaut to leave the earth, travel away and then return at a high speed, and arrive at a time earlier than that at which they left; in other words, it is possible for the astronaut to travel back in time? Why or why not? I don't quite understand his Theory of Relativity. Can someone explain it? 10 points for best answer.

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• Anonymous
7 years ago
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"Does Einstein's theory of relativity say time travel is possible?"

No, this is the "laws of physics". Only forward in time, in contact with every instant.

"Einstein's Theory of Relativity states that time is relative, so would that mean it is possible for an astronaut to leave the earth, travel away and then return at a high speed, and arrive at a time earlier than that at which they left;"

No. The astronaut and the Earth agree on the ship's speed. Let's pretend they get impossibly close to c, and go to the nearest star at 4.3 light years. They will get there and return in almost zero time. For us, the trip takes 8.6 years, minimum.

"in other words, it is possible for the astronaut to travel back in time?"

No.

"Why or why not? Idon't quite understand his Theory of Relativity."

The "laws of physics" that you measure in your laboratory will not tell you how fast or in which direction you are moving. That is pretty much it. It allows you to correctly infer what relatively moving observers will measure about events and distances in the Universe.

• 7 years ago

To the future yes

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://en.wikipedia.org/wiki/Grandfather_paradox

http://science.howstuffworks.com/science…

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.

• 7 years ago

Not sure if Einstein addressed time travel specifically, but Stephen Hawking has said that based on Einstein's theory, time travel is possible, but only forward, not back. If someone approaches the speed of light, time slows down for them compared to those on earth. So, upon their return the will have "travelled" to the future.

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