Physicists find shortcuts to see the elusive quantum glow

There are many strange and wonderful concepts in theoretical physics, such as wormholes, quantum bubbles, and the multiverse. The problem is that while such things easily emerge from the theorist’s equations, it is virtually impossible to create and test in a laboratory setting. However, one such “untestable” theory could be an impending experimental setup.

Researchers at the Massachusetts Institute of Technology and the University of Waterloo, Ontario say they have found a way to test the Unlu effect, a strange phenomenon that is expected to occur from objects moving in empty space. If scientists can observe the effect, this feat can confirm long-standing assumptions about black hole physics.Their suggestion is Physical review letter April 21st.

If you can observe the Unruh effect directly, it may look like you are jumping into hyperspace. Millennium Falcon— A sudden rush of light otherwise bathed in a black void view. As an object accelerates in a vacuum, it is wrapped in a warm cloak of glowing particles. The faster the acceleration, the warmer the glow. “It’s very strange,” explains MIT quantum physicist Vivishek Sudhir, one of the co-authors of the study, because the vacuum is supposed to be above the definition. “As you know, where did this come from?”

Where it came from has to do with the fact that the so-called empty space is not completely empty, but is filled with overlapping energy quantum fields. Fluctuations in these fields can generate photons, electrons, and other particles, which can disperse sparks by accelerating objects. In essence, an object that passes through a vacuum immersed in a field at high speed gets some of the energy in the field and is then re-emitted as Unruh radiation.

The name of this effect comes from the theoretical physicist Birunlu, who explained the phenomenon that bears his name in 1976. However, two researchers, mathematician Stephen Fullerling and physicist Paul Davis, independently created the formula within three years of Unru (1973 and 1975, respectively). ).

“I remember it vividly,” says Davis, now a professor of regent at Arizona State University. “I didn’t have a desk or office, so I sat down on his wife’s dressing table and did the calculations.”

A year later, Davis met Unru at a conference where Unru was speaking about his recent progress. Davis was surprised to hear that Unru explained a phenomenon very similar to what was revealed from his bathroom calculations. “So we then got together at the bar,” recalls Davis. The two soon started a collaboration that lasted for several years.

Davies, Fulling and Unruh all worked on their work from a purely theoretical point of view. They didn’t expect anyone to design a real experiment around it. However, as technology advances, it is possible that ideas that were once entrusted to the world of theory, such as gravitational waves and the Higgs boson, can actually be observed. And it turns out that observing the Unruh effect can help solidify another distant concept of physics.

“The reason people are working on the Unlu effect is not because they think accelerated observers are very important,” said Michigan State University’s physics, astronomy, and molecular biology, which were not involved in the study. Says Christoph Adami, a professor of scholarship. “They are working on this for a direct connection to black hole physics.”

In essence, the Unruh effect is the flip side of a much more famous physical phenomenon. Hawking radiation is named after the physicist Stephen Hawking. Hawking radiation theorized that as the black hole slowly evaporates, a halo of light that is almost imperceptible should leak out of the black hole.

In the case of Hawking radiation, its warm fuzzy effect is essentially the result of gravity pulling particles into a black hole. But in the case of the Unruh effect, it’s a matter of acceleration. That is, according to Einstein’s equivalence principle, gravity is mathematically equal.

Imagine you are standing in an elevator. The impact causes the car to run up to the next floor, and for a moment I feel myself being pulled towards the floor. From your point of view, “it is essentially indistinguishable from the sudden rise in Earth’s gravity,” Sudhir says.

He says the same can be said from a mathematical point of view. “It’s just as easy. There is an equivalence between gravity and acceleration,” Sudhir adds.

Despite its theoretical excellence, scientists have not yet observed the Unruh effect. (Furthermore, no Hawking radiation was seen.) This is because it has long been considered very difficult to experimentally test the Unruh effect. In most cases, researchers need to expose objects to 25 or more ridiculous accelerations. Senjo Double the force of Earth’s gravity to produce a measurable emission. Alternatively, you can use more accessible accelerations, but in that case it is very unlikely that they will produce a detectable effect, so such experiments need to be performed continuously for billions of years. there is. But Sudhir and his co-authors believe they have found a loophole.

Researchers have been able to “stimulate” particles and artificially raise them to high-energy states by grabbing a single electron in a vacuum with a magnetic field and accelerating it through a carefully constructed photon bath. I noticed. This added energy doubles the effect of acceleration. In short, by using the electron itself as a sensor, researchers can pick up the Unruh radiation that surrounds the particles without applying too much G-force (or waiting for decades).

Unfortunately, the energy-enhancing photon bus also adds background “noise” by amplifying other quantum field effects in vacuum. “That’s exactly what we don’t want to happen,” says Sudhir. However, by carefully controlling the electron orbits, the experimenter should be able to negate this potential interference. This is like Sudhir throwing an invisible cloak over a particle.

Also, unlike the kits needed for most other state-of-the-art particle physics experiments, such as the giant superconducting magnets and vast beamlines of CERN’s Large Hadron Collider, researchers have simulated the Unlu effect. Can be set up in most university laboratories. “It doesn’t have to be a big experiment,” says Barbara Shoda, a physicist at the University of Waterloo and co-author of the paper. In fact, Sudhir and his PhD are currently designing a version that students will actually create and hope to do so in the coming years.

Adami sees the new research as an elegant integration of several different disciplines, such as classical physics, atomic physics, and quantum field theory. “I think this paper is correct,” he says. But, like the Unruh effect itself, “to some extent it is clear that this calculation was done before.”

For Davis, the possibility of testing the effect could open exciting new doors in both theoretical physics and applied physics, while expanding the toolkits that experimenters can use to study nature. We will further examine the almost unobservable phenomenon predicted by theorists. “The thing about physics that makes it such a successful field is that experimentation and theory are very closely related,” he says. “The two are in the lock step.” Testing the Unruh effect promises to be the best result for both.


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