“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.”
- January 8, 1942 – March 14, 2018
- British
- Theoretical physicist, science writer
- Announced the black hole singularity theorem and Hawking radiation, and contributed to the popularization of science with his book “Talking about the Universe”
Quote
“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.”
Explanation
In this quote, Stephen Hawking refers to the theoretical possibility of time travel as proposed by Einstein’s general theory of relativity. Initially, time travel was considered a purely science fiction concept, with fantastical stories of people traveling to the past or future in machines, such as in H.G. Wells’ The Time Machine. However, Einstein’s general theory of relativity, which describes how gravity influences the fabric of space-time, opened the door to the idea that time travel might be possible under certain conditions, based on the geometry of space-time itself.
According to relativity, space and time are not separate, fixed entities but are instead intertwined into a four-dimensional fabric called spacetime. The theory allows for the possibility that extreme gravitational fields or certain curved geometries of space-time could, in theory, create loops or closed timelike curves (CTCs), which would allow time travel to the past or future. For example, a massive object like a rotating black hole (or Kerr black hole) might create a distortion in spacetime that could allow a rocket to enter and, theoretically, travel back in time. This idea, though speculative and requiring conditions that are beyond our current technological capabilities, suggests that space-time warping could enable time travel under the right circumstances.
Hawking’s reference to this possibility underscores the significant role that theoretical physics plays in exploring ideas that initially seem impossible. While time travel remains far from achievable, the notion that it is mathematically plausible within the framework of general relativity challenges our intuitions about the nature of time and space. Hawking’s work on black holes and the unification of quantum mechanics and relativity also links back to the larger goal of understanding how the laws of physics might allow for extreme phenomena like time travel, as well as the potential limits of these possibilities. Despite the speculative nature of time travel, this kind of inquiry drives scientific progress and encourages new ways of thinking about the universe, its structure, and our place within it.
