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  • We’ve just doubled the number of gravitational waves we can find

    We’ve just doubled the number of gravitational waves we can find

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    Gravitational wave detectors use laser beams in tubes that span kilometres

    The Virgo Collaboration

    Gravitational waves that span thousands to billions of miles can be obscured in our detectors by the smallest of quantum fluctuations that permeate space-time. But now, researchers at the Laser Interferometer Gravitational-Wave Observatory (LIGO) have found a way to beat this quantum noise. And as a result, they are finding nearly twice as many cosmic events as before.

    “We realised that quantum noise will be limiting us a long time ago. It’s not just a fancy [quantum] thing to demonstrate, it’s something that really affects the actual detector,” says Wenxuan Jia at the Massachusetts Institute of Technology.

    LIGO detects gravitational waves, ripples in the fabric of space-time created by dramatic cosmic events like collisions between black holes. To do so, it fires a laser beam along each of its two 4-kilometre-long arms, which sit perpendicular to each other. A passing gravitational wave squashes and expands the part of space-time where these arms reside, introducing a small difference between the distances travelled by the two beams.

    But that discrepancy is so tiny it can be hard to tell when it is caused by gravitational waves and when it is due to the nearly-imperceptible flickers of quantum fields that permeate all of space, including the laser light itself. The researchers found changing the quantum properties of the light could help them suppress the crackles of quantum fields and get a more distinct gravitational wave signal.

    They added a series of devices to the detector, including a special crystal and several lenses and mirrors, which all work together to “squeeze” LIGO’s light into a quantum state where correlations between light particles diminish the flickering.

    LIGO completed its first run with squeezed light in 2020, but the method only worked for gravitational waves with relatively high frequencies – those with lower frequencies actually produced more noisy signals than before. Jia and his colleagues modified the squeezing process to work equally well at both high and low frequencies before LIGO’s 2023 run. This change had a stunning effect: the number of gravitational waves it detected nearly doubled, effectively allowing the machine to reveal a larger part of our universe.

    “Pushing the boundaries of quantum measurement has pushed the boundaries of space-time measurement, which is truly a beautiful thing,” says Chad Hanna at the Pennsylvania State University. He says this advanced precision will enable LIGO to see black hole mergers “all the way back to the formation of the first stars”.

    Bruce Allen at the Max Planck Institute for Gravitational Physics in Germany says there are several new kinds of gravitational waves physicists would like to see with LIGO’s newfound precision. This includes those emitted constantly by bumpy neutron stars as they rotate, as opposed to the ones they emit when they collide with something, which has been the origin of most gravitational waves detected to date.

    The upgrade also opens the door for fully new discoveries, as it could help probe the gravitational wave background that permeates space-time. “Every time you increase the sensitivity [of your detectors], you increase your chances of encountering the unexpected,” says Allen.

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  • We physicists could learn a lot by stepping beyond our specialisms

    We physicists could learn a lot by stepping beyond our specialisms

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    A century ago, it was possible for a physicist to know almost everything there was to know about physics. Now, this is far from the case. It isn’t that the physicists of today are less competent. The problem is that humans simply know so much about the inner workings of the universe that it is impossible for someone to be deeply familiar with all of it. As a result, today’s tendency is to produce specialists.

    For example, I trained initially as a relativist: general relativity and quantum extensions of it, applied to cosmology, were my specialist areas of physics. Eventually,…

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  • Black hole jets on the scale of the cosmic web

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  • We finally know exactly how dark deep space is

    We finally know exactly how dark deep space is

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    NASA’s New Horizons spacecraft in deep space

    NASA, APL, SwRI, Serge Brunier (ESO), Marc Postman (STScI), Dan Durda

    We finally know just how dark it is in deep space. NASA’s New Horizons spacecraft has made the first precise measurements of the ambient light that suffuses the universe, called the cosmic optical background.

    The cosmic optical background is so dim that it is impossible to measure with any precision from Earth – the glow of objects in the inner solar system far outshines it. “Every time you try to measure it from Earth, or from near Earth, you’re going to…

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  • How Einstein was both right and wrong about gravitational waves

    How Einstein was both right and wrong about gravitational waves

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    Gravitational waves are vibrations in space-time itself

    Peter Jurik/Alamy

    The following is an extract from our Lost in Space-Time newsletter. Each month, we hand over the keyboard to a physicist or mathematician to tell you about fascinating ideas from their corner of the universe. You can sign up for Lost in Space-Time for free here.

    From our current vantage point, gravitational waves appear to be a ubiquitous phenomenon in the cosmos. The first detection of these ripples in space-time came in September 2015 at the Laser Interferometer Gravitational-Wave Observatory (LIGO). The waves captured were the by-product of a…

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  • This mind-blowing map shows Earth’s position within the vast universe

    This mind-blowing map shows Earth’s position within the vast universe

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    New Scientist. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine.

    This story is part of our Cosmic Perspective series, in which we confront the staggering vastness of the cosmos and our place in it. Read the rest of the series here.

    This map shows the circle of the cosmos that surrounds us, extending to a distance of 200 million light years. At this scale, space is comprised of clusters of galaxies and voids, the latter being areas with relatively few galaxies. The Milky Way, at the centre, is part of the Local Group of galaxies, with the Virgo cluster our nearest neighbour.

    Majestic spiral

    The Milky Way’s spiral structure is dominated by two main arms called Scutum-Centaurus and Perseus. It also features a dense region known as the central bar. Our solar system lies on a more modest structure called the Orion spur.

    However tangled the question of our metaphorical place in the universe, we can use astronomy to grasp Earth’s physical location.

    Earth orbits the sun at a distance of 150 million kilometres and the sun orbits the centre of the Milky Way. Specifically, we are in the Orion arm, around 26,500 light years from the centre.

    The Milky Way resides in the Local Group of galaxies. About 2.5 million light years away is our closest neighbouring galaxy, Andromeda, the largest galaxy in the Local Group. Right now, we are hurtling towards Andromeda at more than 100 kilometres per second; in about 4 billion years, the two galaxies will collide.

    The Local Group

    That will shake up the Local Group, but it will be barely a blip on the radar of the wider cosmic neighbourhood.…

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  • The universe is built a lot like a giant brain – so is it conscious?

    The universe is built a lot like a giant brain – so is it conscious?

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    An astrophysicist and a surgeon walk into a bar. No, this isn’t the start of a bad joke. A few years ago, astrophysicist Franco Vazza met his childhood friend Alberto Feletti, who had become a neurosurgeon. As they reminisced and chatted about their work – Vazza modelling the structure of the universe, Feletti poring over the composition of the brain – a thought struck them: why not compare the two?

    Vazza, based at the University of Bologna, Italy, did just that. He used statistical methods to compare the neurons in one area of the brain, the cortex, with the cosmic web, the pattern of matter distribution across the universe. Vazza looked at the number of nodes in each network and how densely each node was connected. The results surprised him. “It is a tantalising level of similarity,” he says. The structures differ in size by some 27 orders of magnitude. But if you ignore that, “the two patterns sort of overlap”, says Vazza.

    For some physicists, this likeness is too tempting to ignore. Some have even suggested the possibility that the universe “thinks” or is in some sense conscious, an idea with roots in the philosophy of panpsychism.

    Traditionally, researchers explained consciousness in one of two ways. Materialists say matter is all there is and consciousness – somehow – emerges from it. Dualists say there are fundamentally two kinds of stuff: matter stuff and consciousness stuff. Much ink has been spilled on the shortcoming of both ideas. For instance, how exactly does consciousness arise from pure matter?

    Panpsychism

    For some,…

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  • We are closer than ever to finally proving the multiverse exists

    We are closer than ever to finally proving the multiverse exists

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    Shutterstock/Dr. Norbert Lange

    We think our universe contains everything that exists, has ever existed and will exist in the future. But this might not be the case: there are many ways other universes could exist.

    One is that we could be a single part of a branch of infinite universes known collectively as the multiverse. These universes might have appeared shortly after the big bang, they might be hiding in extra dimensions or they could pop into existence whenever a quantum property goes from a cloud of possible states to a single reality.

    Multiverse ideas gained scientific weight in the 1980s with the invention of inflation, a period when the early universe suddenly expanded. Inflation explains why the cosmos is so flat and smooth, but it also predicts the creation of a multitude of independent bubble universes.

    Cyclic universes

    Yet inflation is just one route to a multiverse, and it has its critics. In recent years, many cosmologists have turned to alternatives like cyclic universe theories, which say the universe is on an unending cycle between ballooning and compressing. These theories still invoke multiple universes, but at different times.

    “What I didn’t like about inflation was that there are very few genuine predictions – you don’t get out much more than you put in,” says Neil Turok, a physicist at the University of Edinburgh, UK, who helped develop a model for a cyclic universe, published in 2001, as a rival for inflation. “It just struck me that there has to be a better explanation.”

    The cyclic universe has its…

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  • Odd black holes smaller than protons may have once littered the cosmos

    Odd black holes smaller than protons may have once littered the cosmos

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    Colour-charged black holes may have formed in the early universe

    betibup33/Shutterstock

    The universe may have once been speckled with tiny black holes with a strange property called colour charge. These exotic objects, if they existed, would have formed in the instants after the big bang and evaporated just as quickly, but they could have upset the balance of elements that formed in the early universe.

    Minuscule black holes formed right at the beginning of the cosmos are known as primordial black holes. Because of their…

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  • What “naked” singularities are revealing about quantum space-time

    What “naked” singularities are revealing about quantum space-time

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    New Scientist. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine.

    adbobe stock/Erika Eros/Alamy/collarge ryan wills

    Deep inside a black hole, the cosmos gets twisted beyond comprehension. Here, at some infinitesimal point of infinite density, the fabric of the universe gets so ludicrously warped that Albert Einstein’s general theory of relativity, which describes how mass bends space-time, ceases to make sense. At the singularity, our understanding falls apart.

    As daunting as singularities are, each one is at least safely tucked away inside the event horizon of a black hole, the boundary beyond which we can’t see. This not only cloaks them from view, but also stops unknown effects they herald, namely the horrors of unpredictability, from leaching out into the wider universe. But what if singularities could exist outside black holes after all?

    That question, given fresh impetus in recent years by demonstrations that general relativity allows for this, has spurred theorists to probe singularities from a deeper perspective, folding in insights from the latest forays into the possible quantum foundations of gravity. Already, they are realising that this new approach “flips the script” on how we think about singularities, says Netta Engelhardt at the Massachusetts Institute of Technology.

    Fair warning: the work takes us into some labyrinthine physics. But by grappling with singularities in this way, Engelhardt and her colleagues are deciphering the enigmatic connections between the quantum realm and classical gravity – and reinforcing the revolutionary idea that…

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