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      No, physicists didn’t make a real wormhole. What they did was still pretty cool

      news.movim.eu / ArsTechnica · Friday, 2 December, 2022 - 19:14 · 1 minute

    Illustration of a new quantum experiment that studies traversable wormholes.

    Enlarge / Artist's illustration of a quantum experiment that studies the physics of traversable wormholes.

    Wormholes are a classic trope of science fiction in popular media, if only because they provide such a handy futuristic plot device to avoid the issue of violating relativity with faster-than-light travel. In reality, they are purely theoretical. Unlike black holes—also once thought to be purely theoretical—no evidence for an actual wormhole has ever been found, although they are fascinating from an abstract theoretical physics perceptive. You might be forgiven for thinking that undiscovered status had changed if you only read the headlines this week announcing that physicists had used a quantum computer to make a wormhole, reporting on a new paper published in Nature.

    Let's set the record straight right away: This isn't a bona fide traversable wormhole—i.e., a bridge between two regions of spacetime connecting the mouth of one black hole to another, through which a physical object can pass—in any real, physical sense. "There's a difference between something being possible in principle and possible in reality," co-author Joseph Lykken of Fermilab said during a media briefing this week. "So don't hold your breath about sending your dog through a wormhole." But it's still a pretty clever, nifty experiment in its own right that provides a tantalizing proof of principle to the kinds of quantum-scale physics experiments that might be possible as quantum computers continue to improve.

    "It’s not the real thing; it’s not even close to the real thing; it’s barely even a simulation of something-not-close-to-the-real-thing," physicist Matt Strassler wrote on his blog . "Could this method lead to a simulation of a real wormhole someday? Maybe in the distant future. Could it lead to making a real wormhole? Never. Don’t get me wrong. What they did is pretty cool! But the hype in the press? Wildly, spectacularly overblown."

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      Black holes can’t trash info about what they swallow—and that’s a problem

      news.movim.eu / ArsTechnica · Monday, 3 October, 2022 - 13:45

    Black holes can’t trash info about what they swallow—and that’s a problem

    Enlarge (credit: Aaron Horowitz/Getty Images)

    Three numbers.

    Just three numbers—that’s all it takes to completely, unequivocally, 100 percent describe a black hole in general relativity. If I tell you the mass, electric charge, and spin (i.e., angular momentum) of a black hole, we’re done. That’s all we’ll ever know about it and all we’ll ever need to describe its features.

    Those three numbers allow us to calculate everything about how a black hole will interact with its environment, how objects around it will respond to it, and how the black hole will evolve in the future.

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