How time travel is theoretically possible?

Question

Can someone explain to me how it is theoretically possible to time travel. How can time travel comply with the laws of nature? My friend was trying to explain this to me, but I'm still trying to figure some parts out.

Answer 1

First you have to realize that time is not what we originally expected it to be. Einstein theorized that an object experiences time much quicker if it moves really fast. This is called the Theory of Relativity.

So for example, if you were to start two timers, one on your wrist and one at your home, and you flew almost at the speed of light around the world until your wrist watch said 30 seconds and flew back home, then you'd be pretty confused to see that the timer at home was much further ahead than your wrist watch. So you've effectively travelled into the future.

Check out this documentary on time travel, he explains travelling back in time.

Answer 2

To understand time travel, you have to come to terms with the idea of time as a dimension, just like width, height, and length of an object. A point in 3-dimensions can be desribed by 3-coordinates (e.g. x = 0, y = 1, z = 2). If the point moves along one of these three axes then it has traveled along this axis in the same sense that a point in 4-dimensions (x, y, z, and t for time) has traveled along the time dimension as time passes. For example, consider the book on your desk. Let give it arbitrary 3D coordinates (1, 2, 3). Now although this book is presumably still on your desk, it is really travelling in time (just like we all are). So the book in 4D has the coordinates (1, 2, 3, 10:30:00pm), then a second later is (1, 2, 3, 10:30:01pm) and so on and so forth.

Now that we have come to terms with time as a physical dimension that we are constantly traveling forward on, let's consider time travel.

1. Traveling to the future: This is the easy one. We are right now all traveling to the future just with the passage of time. On planet earth, 1 sec in China is 1 sec in the USA (+/- very minute differences due to the Earth's rotational speed at the point the second is measured). And when it's 1 second later in China, it's 1 second later in the USA. Well, you say, this is pretty trivial, and I would agree up to a point. The question is WHY IS 1 SEC IN CHINA THE SAME AS 1 SEC IN THE USA? And the answer is because China is travelling through space at pretty much the same speed that the USA is travelling through space because they are both attached to planet Earth which is travelling at a given speed through space. The interesting part is what happens when you travel at a much faster rate than that of your original frame of reference? The answer is that you travel to the future. Here's how this happens: Say on Jan. 1, 2007, you take off in your space ship to travel to a galaxy far far away. You say goodbye to your twin brother on Earth where you are both the same age, let's say 21. You jump into the ship and off you go into space travelling at the speed of light. The trip takes you a year to get to your destination (which means that your destination is 1 light year away). By the time you get to your desintation, you are 22 years old. As soon as you get to the galaxy, you take a few pictures, and you make your way back home. The return trip takes you another year travelling at the speed of light. By the time you get back to Earth, you're 23 now. Your space ship lands, you get out of it and there's your twin brother who you have left 2 years ago space-ship time, but heck he's 80 years old now. How can your twin brother by 80 years old while you're still 23? Because you were travelling at the speed of light, the closer to which you get, the slower time passes, so effectively you have traveleld 57 years into the future Earth time.

Now you might ask why and how does time slow down when you travel at the speed of light? At the molecular level, inside your body, how do your cells know that it's less time passing? There is no real explanation to why you physically age slower, only that time passes slower.

2. Traveling BACK in time: Here's the tough one. No one has a plausible answer that could be explained here. A major obstacle to backwards time travel is the issue of causality. What if you go back in time and kill yourself as an infant? Go figure that one out. Another observation (highly unscientific) is if time travel was to ever be possible, where are the tourists from the future? If anybody attempts to convince you that there is a plausible theory on backwards time travel out there, be very skeptical.

All in all, an interesting subject.

Answer 3

physicists have rejected for many years that you CANT go back in time or reverse time....has to do with quantum mechanics and the quorum unity of space and time in which Einstein theory of relatively show to be true......but wormholes differentials would produce a "plank effect" in which energy of a whole sun would have to be used to move a person an inch in space and time....it is the natural law "for every action there is a reaction".....

Answer 4

Travelling to the future is easy - you are doing it now.

Travelling to the past is impossible. Theoretically and practically. It violates conservation of energy and 2nd law of thermodynamics, to name but two. So its no wonder you could not follow your friend's explanation - because it was wrong.

Answer 5

the answer lies in Einstein's theory of relativity.
in a nutshell, as you go on moving fatser and faster, time goes on slowing down for you. when you reach the speed of light, time freezes. now if somehow you are able to move faster than light, you start going back in time.