Tech

Symmetry reveals clues to three-dimensional universe


We already know about gravity since Newton’s hypothetical encounter with the apple, but we’re still struggling to understand it. While the other three forces of nature are all due to the action of the quantum field, our best theory of gravity describes it as warped spacetime. For decades, physicists have tried to use quantum field theory to describe gravity, but those efforts have been far from perfect.

One of the most promising efforts treats gravity as something like a hologram — a three-dimensional effect bouncing off a flat, two-dimensional surface. Currently, the only concrete example of such a theory is Letters from AdS / CFT, where a particular type of quantum field theory, known as conforming field theory (CFT), gives rise to a gravitational force in space known as anti-de Sitter (AdS). In the strange curves of AdS space, a finite boundary can encapsulate an infinite world. Juan Maldacenadiscoverer of the theory, called it “the universe in a bottle”.

But our universe is not a bottle. Our universe is (mostly) flat. Any bottle containing our flat universe would have to be far away in space and time. Physicists call this cosmic capsule the “heavenly sphere”.

Physicists want to define the rules for a CFT that can give rise to gravity in a world without the curves of AdS space. They were looking for the CFT for flat space — the celestial CFT.

The celestial CFT is even more ambitious than the corresponding theory in AdS/CFT. Since it lives on a sphere of infinite radius, the concepts of space and time are disrupted. Therefore, the CFT will be independent of space and time; instead, it can explain how space and time exist.

Recent research results have given physicists hope that they are on the right track. These results use basic symmetries to constrain what this CFT might look like. Researchers have discovered a surprising set of mathematical relationships between these symmetries – relationships that have appeared previously in certain string theory, leading some to wonder Ask if the connection is a coincidence.

“There is a very large, wonderful animal out here,” said Nima Arkani-Hamed, a theoretical physicist at the Institute for Advanced Study in Princeton, New Jersey. “Hopefully what we’ll find will be quite interesting.”

Symmetry on Sphere

Perhaps the primary way that physicists probe the fundamental forces of nature is to blast particles together to see what happens. The technical term for this is “distributed.” At facilities like the Large Hadron Collider, particles fly in from distant points, interact, then reach detectors in any of the variable states dictated by quantum forces.

If the interaction is dominated by any of the three forces other than gravity, physicists could, in principle, calculate the results of these scattering problems using quantum field theory. . But what many physicists really want to understand is gravity.

Fortunately, Steven Weinberg shows in the 1960s it was possible to compute a number of quantum gravitational scattering problems – those related to low-energy gravity – that could be computed. In this low energy limit, “we have nailed the behavior”, says Monica Pate of Harvard University. “Quantum gravity reproduces the predictions of general relativity.” Astronomers like Pate and Sabrina Pasterski of Princeton University is using these low-energy scattering problems as a starting point to define some of the rules that the hypothetical celestial CFT must obey.

They do this by looking for symmetry. In the scattering problem, physicists calculate the products of scattering — the “scattered amplitude” — and what they look like when they hit detectors. After calculating these amplitudes, the researchers look for patterns that the particles produce on the detector, which correspond to the rules or symmetries to which the scattering process must obey. Symmetry requires that if you apply certain transformations to the detector, the result of a scattering event will not change.



Source link

news7g

News7g: Update the world's latest breaking news online of the day, breaking news, politics, society today, international mainstream news .Updated news 24/7: Entertainment, Sports...at the World everyday world. Hot news, images, video clips that are updated quickly and reliably

Related Articles

Back to top button