The mysterious quantum-mechanical phenomenon involving warm light visible only to fast-moving observers, long thought to be almost impossible to detect, should be measured in the laboratory. So say, three physicians in Canada and the US believe that “the effect of Unruh” can be seen by speeding up an electron in a well-defined way while being showered with microwaves. Evidence of the effect, they calculate, should be available within just a few hours of viewing – unlike the signature from radioactive particles, which may take longer than the history of the universe to appear.
The particular relation theory, revealed by Albert Einstein back in 1905, applies to slow-moving viewers – those in the “inertial” reference frame. It tells us that some very unusual effects occur when one viewer moves about another near light speed – which includes the fact that time and speed are no longer absolute quantities but depend on the viewer’s reference frame. However, this theory does not comment on the effects of acceleration.
Theologians investigated the problem in the 1970s, wanting to find out what a quick-witted viewer would face as he walked through the deep space. William Unruh, Stephen Fulling, and Paul Davies have found that even though the casual observer sees nothing special, the fast-moving person will be filled with warm (limited) light of particles from the quantum vacuum – which slightly increases the temperature in their reference frame. From zero to another approximate value.
Excessive acceleration: However, the effect is minimal. To measure the temperature in just 1 K, the viewer will need to accelerate to 1020 m / s2 – more than anything else can be achieved. Such acceleration can be achieved by electrons embedded within the accelerator of powerful particles, but still, the chances of getting a (possible) object are slim – only one in 1018 per second.
In recent work in Canada, Barbara Šoda and Achim Kempf of the University of Waterloo adopted a new method of calculating quantum acceleration results. In particular, they are looking at ways to improve the chances of particles getting the Unruh effect by exposing them to electrical rays as fast. They explain that the magnification of the Unruh effect is “inspired” concerning the standard, automatic variant compared to the difference between mechanical light output and atomic stimulation – this is ultimately applied to laser technology.
When they do algebra, they conclude that the probability of seeing the effect of Unruh regenerated increases proportionally with the number of photons in the radiation (compared to the default effect). Therefore, reducing the time required to observe the impact by sending an accelerated electron to the magnetic field should be possible. Pointing out that modern microwave ovens can hold about 1015 photons, they think a measurable effect can be seen within just a few hours of observation.
Vivitek Sudhir and colleagues are currently developing appropriate testing to produce such acceleration at the Massachusetts Institute of Technology in the US. Sudhir, who has collaborated with Šoda and Kempf in a recent study, says the idea is to use a ‘cryogenic’ table-top ‘microwave cavity’ to activate and accelerate one electron and measure the electron deceleration in a laboratory setting. Of reference as it releases and absorbs Unruh photons from its accelerated frame. But he is reluctant to explain how to accelerate and how he and his colleagues aim to gain the necessary balance sensitivity.
Indeed, Anatoly Svidzinsky of Texas A&M University in the US doubts that Unruh’s result could be obtained directly by testing. He says the paper published by him and his colleagues last year was based on current work, using the concept of negative frequency (or power). He argues that renewal without absorption can be legally achieved without an external photon source but depends on self-aggrandizement – the fact that Unruh extraction from one or more fast-moving atoms in its earth state should motivate other particles within the group to do the same (conservation of energy meaning that photons cannot be absorbed). But he warns that the result will be small in any real test.