Time travel is a scientific concept in which an object moves between different points in time in the same way as as it would between different points in space. In early 1900’s, Einstein’s theories that space and time form a four-dimensional fabric known as space-time which can be warped as speed or mass is increased did more than anything else to draw serious scientific attention to the field of study, and currently theoretical physicists usually consider the topic in conjunction with quantum physics or wormholes (Einstein–Rosen bridges).
Here are some interesting quotes on a topic full of uncertainty that has sharply divided scientists for decades. But as Stephen Hawking explains, “even if it turns out that time travel is impossible, it is important that we understand why it is impossible.”
H.G. Wells (Writer)
“Man can go up against gravitation in a balloon, and why should he not hope that ultimately he may be able to stop or accelerate his drift along the Time-Dimension, or even turn about and travel the other way.”
Albert Einstein (Theoretical Physicist)
“People like us, who believe in physics, know that the distinction between past, present and future is only a stubbornly persistent illusion.”
Stephen Hawking (Theoretical Physicist)
“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.”
David Deutsch (Physicist)
“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.”
Clifford A. Pickover (Writer)
“Today, we know that time travel need not be confined to myths, science fiction, Hollywood movies, or even speculation by theoretical physicists. Time travel is possible. For example, an object traveling at high speeds ages more slowly than a stationary object. This means that if you were to travel into outer space and return, moving close to light speed, you could travel thousands of years into the Earth’s future.”
Martin Ringbauer (Physicist)
“The question of time travel features at the interface between two of our most successful yet incompatible physical theories – Einstein’s general relativity and quantum mechanics. Einstein’s theory describes the world at the very large scale of stars and galaxies, while quantum mechanics is an excellent description of the world at the very small scale of atoms and molecules.”
Michio Kaku (Theoretical Physicist)
“In Einstein’s equation, time is a river. It speeds up, meanders, and slows down. The new wrinkle is that it can have whirlpools and fork into two rivers. So, if the river of time can be bent into a pretzel, create whirlpools and fork into two rivers, then time travel cannot be ruled out.. 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.”
Tim Ralph (Physicist)
“The properties of quantum particles are fuzzy or uncertain to start with. This gives them enough wiggle room to avoid inconsistent time travel situations.. Our study provides insights into where and how nature might behave differently from what our theories predict.”
Brian Greene (String Theorist)
“The basic idea if you’re very, very optimistic is that if you fiddle with the wormhole openings, you can make it not only a shortcut from a point in space to another point in space, but a shortcut from one moment in time to another moment in time.”
Brian Cox (Physicist)
“In General Relativity, you can do it in principle. It’s to do with building these things called wormholes; shortcuts through space and time. But most physicists doubt it. Hawking came up with the ‘chronology protection conjecture’ – physics we don’t yet understand – that means wormholes are not stable.. [re travelling between different dimensions] We look for extra dimensions at the LHC (Large Hadron Collider). You can imagine extra dimensions in space, and that we are living on a sheet of higher dimensional space.”
J. Richard Gott (Astrophysicist)
“Cosmic strings are either infinite or they’re in loops, with no ends. So they are either like spaghetti or Spaghetti Os. The approach of two such [loop] strings parallel to each other, will bend space-time so vigorously and in such a particular configuration that [it] might make time travel possible – in theory. This is a project a super civilization might attempt,” says Gott. “It’s far beyond what we can do. We’re a civilization that’s not even controlling the energy resources of our planet.””
Ronald Mallett (Theoretical Physicist)
“As physicists, our experiments deal with subatomic particles. How soon humans will be able to time travel depends largely on the success of these experiments, which will take the better part of a decade. And depending on breakthroughs, technology, and funding, I believe that human time travel could happen this century… The Grandfather Paradox [where you go back in time and kill your grandfather] is not an issue. In a sense, time travel means that you’re traveling both in time and into other universes. If you go back into the past, you’ll go into another universe. As soon as you arrive at the past, you’re making a choice and there’ll be a split. Our universe will not be affected by what you do in your visit to the past.”
Douglas Adams (Writer)
“If the Universe came to an end every time there was some uncertainty about what had happened in it, it would never have got beyond the first picosecond. And many of course don’t. It’s like a human body, you see. A few cuts and bruises here and there don’t hurt it. Not even major surgery if it’s done properly. Paradoxes are just the scar tissue. Time and space heal themselves up around them and people simply remember a version of events which makes as much sense as they require it to make.”