Scientists have created a lab-grown analog of a black hole to test one of Stephen Hawking’s most famous theories — and it behaves exactly as he predicted.
The experiment, created by using a single row of atoms to simulate a black hole’s event horizon, has added further evidence to Hawking’s theory that black holes should emit a faint glow of radiation from virtual particles randomly orbiting near reveal their limits. . In addition, the researchers found that most of the light particles, or photons, should be produced around the edges of the cosmic samples. The team published their findings Nov. 8 in the journal Physical Review Research.
According to quantum field theory, there is no such thing as an empty vacuum. Space is instead teeming with tiny vibrations that, when imbued with enough energy, randomly shatter into virtual particles — particle-antiparticle pairs that almost instantly annihilate each other, producing light. In 1974, Stephen Hawking predicted that the extreme gravity felt at the mouths of black holes – their event horizon – would elicit photons in this way. Gravity, according to Einstein’s general theory of relativity, distorts space-time, so that quantum fields become more distorted the closer they get to the immense gravitational pull of a black hole’s singularity.
Due to the uncertainty and strangeness of quantum mechanics, this distortion creates uneven boxes with differently moving time and subsequent energy spikes across the field. It’s these energy mismatches that cause virtual particles to emerge from what appears to be nothing on the fringes of black holes, before self-destructing to produce a faint glow called Hawking radiation.
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Physicists are interested in Hawking’s prediction because it was made at the extreme boundary of the two great but currently incompatible theories of physics: Einstein’s general theory of relativity, which describes the world of large objects, and quantum mechanics, which explains the strange behavior of the smallest. particles.
But detecting the supposed light directly is something astrophysicists will probably never achieve. First, there are the considerable challenges involved in traveling to a black hole — the closest known one is 1,566 light-years from Earth — and, once there, not being sucked in and spaghetti made by its immense gravity. Second, the number of Hawking photons created around black holes is thought to be small; and would be drowned out in most cases by other light-producing effects, such as the high-energy X-rays spewed out by matter swirling around the black hole’s abyss.
In the absence of a true black hole, physicists have been looking for Hawking radiation in experiments simulating their extreme conditions. In 2021, scientists used a one-dimensional array of 8,000 supercooled, laser-bounded atoms of the element rubidium, a soft metal, to create virtual particles in the form of wave-like excitations along the chain.
Now another atomic chain experiment has achieved a similar feat, this time tuning the ease with which electrons can jump from one atom to the next in line, creating a synthetic version of a black hole’s space-time warping event horizon. arises. After adjusting this tether so that part of it fell over the simulated event horizon, the researchers recorded a temperature spike in the tether — a result that mimicked the infrared radiation produced around black holes. The finding suggests that Hawking radiation could arise as an effect of quantum entanglement between particles located on opposite sides of an event horizon.
Interestingly, the effect emerged only when the hop amplitude transitioned from a few fixed configurations of flat space-time to a warped configuration—suggesting that Hawking radiation requires a change in specific energy configurations of space-time to become produced. Since the powerful gravitational distortions caused by the black hole are absent from the model, it’s unclear what this means for a theory of quantum gravity and for potential naturally produced real Hawking radiation, but it nevertheless offers a tantalizing glimpse into previously unexplored physics .