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Science

LIGO Surpasses the Quantum Limit (sciencealert.com) 22

Wikipedia defines LIGO as "a large-scale physics experiment and observatory designed to detect cosmic gravitational waves." (It stands for Laser Interferometer Gravitational-Wave Observatory — that is, measuring the interference caused by superimposed waves.)

Now Science Alert reports: A technique for squeezing light in the arms of LIGO's interferometer has allowed its measurements to cross the quantum barrier.

For LIGO, it's a bold new realm of sensitivity, giving the gravitational wave detector the ability to find 60% more dead star mergers than the rate of its previous run, which was around one or two detections every week or so... "Now that we have surpassed this quantum limit, we can do a lot more astronomy," says physicist Lee McCuller of Caltech...

LIGO's sensitivity was already absolutely jaw-dropping. The interferometer works by detecting ripples in space-time that are generated by colliding black holes and neutron stars, millions of billions to light-years away. These cause gravitational waves, like ripples in a pond. We can't feel them; but they can be detected in miniscule deviations in the path of light down a long, long tunnel. These deviations are incredibly small, down to trillions of times smaller than a human hair. But once you get into subatomic scales — the quantum realm — LIGO's abilities are hobbled. That's because, on those unimaginably small scales, particles randomly pop in and out of space, creating a constant background hiss of quantum noise that's louder than any signal.

Frequency-dependent squeezing is a way of amplifying the signals to be 'louder' than the quantum noise... If you pinch a property of light, such as amplitude (or power), other properties, such as frequency, can be measured more accurately... [T]he light can be squeezed in multiple ways to amplify the frequency of the gravitational waves the scientists are looking for... "We've known for a while how to write down the equations to make this work, but it was not clear that we could actually make it work until now. It's like science fiction," says physicist Rana Adhikari of Caltech...

This means we're likely to see a significant uptick in the number of black hole and neutron star collisions we observe out there in the wider Universe.

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LIGO Surpasses the Quantum Limit

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  • by sinkskinkshrieks ( 6952954 ) on Monday October 30, 2023 @04:18AM (#63965006)
    I like it. It sounds illegal. Turn on the LIGO detector in case the physics police have a quantum speed trap.
  • Next up, go lower than planck length and blink faster than planck time.

  • Intelligence testing (Score:5, Interesting)

    by mattr ( 78516 ) <mattr @ t e l e b o d y . com> on Monday October 30, 2023 @06:50AM (#63965218) Homepage Journal

    Nice. Not that I'm expecting an advanced species to place a gravitational frequency beacon just below the limit where prospective civilization needs to be able to implement. Just saying.

    • by Sique ( 173459 )
      I don't expect that either. (I rather expect Earth to be one of the earliest planets to have developed Life, as it started just 9 billion years after the Big Bang, when there was just enough metallicity in the universe to even create a rocky planet, and enough icy comets to have it rain on it.)
  • by v1 ( 525388 ) on Monday October 30, 2023 @06:59AM (#63965228) Homepage Journal

    This detector isn't measuring ripples at the ATOMIC level, like "this ripple is about five atoms wide".

    It's measuring ripples on the SUB-atomic level, like "that ripple is 1/1000th the with of a PROTON"

    (and don't forget, the nucleus of an atom, where the proton lives, is less than 1% of the volume of the atom)

    There's just no easy way to wrap your mind around the idea of measuring something THAT small. It makes an electron microscope look like a kid's magnifying glass.

    • You just described measuring something that small... So actually I CAN imagine it.

      But I guess if you have no imagination...
    • What we really need now is somebody who can channel Douglas Adams long enough to come up with a memorable description of just how small that is.
  • Why does the summary begin with a wikipedia definition? Are the summaries being written by high-school essayists now?
    • Why does the summary begin with a wikipedia definition? Are the summaries being written by high-school essayists now?

      Absolutely not. A high school essayist would likely have better spelling and grammar.

      • by Potor ( 658520 )

        Absolutely not. A high school essayist would likely have better spelling and grammar.

        Then what happens to these skills between high school and university?

    • Any article that begins with a definition is always accompanied by some moron who thinks this only started happening around "here".

    • by ceoyoyo ( 59147 )

      Because the editors got tired of being made fun of for not doing anything, so now they copy and paste a gratuitous paragraph off Wikipedia and THEN a paragraph or two of the article.

      • by Potor ( 658520 )
        That's my point. Is there anyone on /. who does not know what LIGO is, or is incapable of figuring that out?
        • by ceoyoyo ( 59147 )

          Yes. Any article that uses an abbreviation and doesn't define it draws several comments about it.

          There's an expression: "damned if you do, and damned if you don't." If you aim for an audience with some knowledge, or at least the ability to use Google, you get whiney, off topic comments about it. If you aim for the unwashed masses, you get whiney, off topic comments about it.

          • by Potor ( 658520 )

            Yes. Any article that uses an abbreviation and doesn't define it draws several comments about it.

            LIGO is not an abbreviation but an acronym ... as long as I'm being whiny.

  • It is stunning to me that a device can be built with such accuracy of laser light to detect ripples at the atomic layer or lower, over such distance.

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