In physics, spacetime (or space-time, space time, space-time continuum) is any mathematical model that combines space and time into a single continuum. Spacetime is usually interpreted with space as being three-dimensional and time playing the role of a fourth dimension that is of a different sort from the spatial dimensions. From a Euclidean space perspective, the universe has three dimensions of space and one dimension of time. By combining space and time into a single manifold, physicists have significantly simplified a large number of physical theories, as well as described in a more uniform way the workings of the universe at both the supergalactic and subatomic levels.
In non-relativistic classical mechanics, the use of Euclidean space instead of spacetime is appropriate, as time is treated as universal and constant, being independent of the state of motion of an observer. In relativistic contexts, time cannot be separated from the three dimensions of space, because the observed rate at which time passes for an object depends on the object's velocity relative to the observer and also on the strength of gravitational fields, which can slow the passage of time.
Kip Stephen Thorne (born June 1, 1940) is an American theoretical physicist, known for his prolific contributions in gravitation physics and astrophysics and for having trained a generation of scientists. A longtime friend and colleague of Stephen Hawking and Carl Sagan, he was the Feynman Professor of Theoretical Physics at the California Institute of Technology (Caltech) until 2009 and one of the world’s leading experts on the astrophysical implications of Einstein’s general theory of relativity. He continues to do scientific research and is also writing a film.
Thorne was born in Logan, Utah, the son of Utah State University professors D. Wynne Thorne and Alison C. Thorne, a soil chemist and an economist, respectively. Raised in an academic environment, two of his four siblings are also professors. He became interested in science at the age of eight, after attending a lecture about the solar system. Thorne and his mother then worked out calculations for their own model of the solar system.
Helen Fay Dowker (born 1965 in Manchester, Lancashire) is a British Theoretical Physicist at Imperial College London.
As a student, she was interested in wormholes and quantum cosmology. Having studied at the University of Cambridge, Dowker was awarded the Tyson Medal in 1987 and completed her Doctor of Philosophy under the supervision of Stephen Hawking in 1990.
Fay Dowker was later a Postdoctoral Researcher at the Fermi National Accelerator Laboratory, at the University of California at Santa Barbara and also the California Institute of Technology.
She is currently a Professor of Theoretical Physics and a member of the Theoretical Physics Group at Imperial College London and an Affiliate of the Institute for Quantum Computing. She conducts research in a number of areas of theoretical physics including quantum gravity and causal set theory.
Dowker was previously a Lecturer at Queen Mary, University of London.