David Deutsch Quotes

Even if it turns out that time travel is impossible, it is important that we understand why it is impossible.

I myself believe that there will one day be time travel because when we find that something isn't forbidden by the over-arching laws of physics we usually eventually find a technological way of doing it.

Time travel is such a magic concept.

The bottom line is that time travel is allowed by the laws of physics.

Time travel was once considered scientific heresy, and I used to avoid talking about it for fear of being labelled a 'crank.'

Originally, the burden of proof was on physicists to prove that time travel was possible. Now the burden of proof is on physicists to prove there must be a law forbidding time travel.

Time travel used to be thought of as just science fiction, but Einstein's general theory of relativity allows for the possibility that we could warp space-time so much that you could go off in a rocket and return before you set out.

Thinking about time travel may seem like something humans have been doing since the first caveman dropped the first rock on his foot. But, even to begin to imagine the possibility of time travel, your mind must be able to wrap itself around the notion of a past and a future.

Time travel is a wonderful thing, isn't it?

I think the idea of time travel is very seductive.

Travel at faster than the speed of light certainly can have dramatic implications that are difficult to understand, such as time travel.

I find the whole time travel question very unsettling if you take it to its logical extension. I think it might eventually be possible, but then what happens?

Time travel offends our sense of cause and effect - but maybe the universe doesn't insist on cause and effect.

I've always been a big fan of time travel, and I'm very into the notion that some day we'll be able to do it. Beam me up!

If time travel were possible, you still wouldn't be able to change the past - it's already happened!

Once the notion of time travel starts to come naturally to the human mind, it is supremely easy to assimilate it into our mode of thinking.

People who think about time travel stories sometimes think that going back in time would be fun because you would have all the information you needed to be much more astute than the people there, when the truth is of course you wouldn't.

Whether you can go back in time is held in the grip of the law of quantum gravity.

Trust me: you make a movie about time travel, and you know for a fact humans will never travel through time. The paradoxes that come up just from trying to tell a story with time travel really illuminates the fact that it's impossible. It will never happen. We can barely get through a movie that involves time travel.

The simplest way out of the puzzle of time travel is to say that it can't be done. That's very likely the right answer. However, we don't know for sure.

Time travel, by its very nature, was invented in all periods of history simultaneously.

The river of time may fork into rivers, in which case you have a parallel reality and so then you can become a time traveler and not have to worry about causing a time paradox.

Imaginary time is a new dimension, at right angles to ordinary, real time.

When you look at the calculation, it's amazing that every time you try to prove or disprove time travel, you've pushed Einstein's theory to the very limits where quantum effects must dominate. That's telling us that you really need a theory of everything to resolve this question. And the only candidate is string theory.

Technologies that may be realized in centuries or millennium include: warp drive, traveling faster than the speed of light, parallel universes; are there other parallel dimensions and parallel realities? Time travel that we mentioned and going to the stars.