About 40 years ago, Canadian physicist William Unruh made a surprising prediction regarding quantum field theory. This is called the Unruh effect. His theory predicted that an accelerating observer would be bathed in blackbody radiation, whereas an inertial observer would be exposed to none. So on the theory’s marking of its 40th anniversary, perhaps we can again consider this theory and how it could affect human beings attempting relativistic space travel in the near future.
This is the intention behind a new study by a team of researchers from Sao Paulo, Brazil. In essence, they consider how the Unruh effect could be confirmed using a simple experiment that relies on existing technology. Not only would this experiment prove once and for all if the Unruh effect is real, but it could also help plan for the day when interstellar travel becomes a reality. To put it in layman’s terms, Einstein’s Theory of Relativity states that time and space are dependent upon the inertial reference frame of the observer. Consistent with this is the theory that if an observer is traveling at a constant speed through empty vacuum, they will find that the temperature of said vacuum is absolute zero. But if they were to begin to accelerate, the temperature of the empty space would become hotter.
This is what William Unruh, a theorist from the University of British Columbia in Vancouver, asserted in 1976. According to his theory, an observer accelerating through space would be subject to a “thermal bath” of photons and other particles and this would intensify the more they accelerated. The new study was recently published in the journal Physical Review Letters under the title “Virtual observation of the Unruh effect.” Led by Gabriel Cozzella of the Institute of Theoretical Physics (IFT) at Sao Paulo State University, they claim that this experiment would settle the issue by measuring an already-understood electromagnetic phenomenon. Essentially, it would be possible to detect the Unruh effect by measuring what is known as Larmor radiation. This refers to the electromagnetic energy that is radiated away from charged particles, such as electrons, protons, and ions, when they accelerate.
Video Courtesy of Youtube:
The experiment would consist of monitoring the light emitted by electrons within two separate reference frames. In the first, to be called the “accelerating frame,” electrons are fired laterally across a magnetic field and this would cause the electrons to move in a circular pattern. In the second, called the “laboratory frame,” a vertical field is applied to accelerate the electrons upwards, causing them to follow a corkscrew-like path. In the accelerating frame, Cozzella and his colleagues assume that the electrons will definitely encounter the “fog of photons” where they both radiate and emit them. In the laboratory frame, the electrons would heat up once vertical acceleration was applied, causing them to show an excess of long-wavelength photons.
No set date has yet been announced for the experiment, but if it does prove successful and space travel could prove dangerous because of the Unruh effect, then we could expect future space travel to be more into cryogenic or hibernation sleep rather than faster-than-light hyper jumps.