Attention to the Unseen

Charlie Wood writes: A jarring divide cleaves modern physics. On one side lies quantum theory, which portrays subatomic particles as probabilistic waves. On the other lies general relativity, Einstein’s theory that space and time can bend, causing gravity. For 90 years, physicists have sought a reconciliation, a more fundamental description of reality that encompasses both quantum mechanics and gravity. But the quest has run up against thorny paradoxes. Hints are mounting that at least part of the problem lies with…

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Charlie Wood writes: Millennia ago, Aristotle asserted that nature abhors a vacuum, reasoning that objects would fly through truly empty space at impossible speeds. In 1277, the French bishop Etienne Tempier shot back, declaring that God could do anything, even create a vacuum. Then a mere scientist pulled it off. Otto von Guericke invented a pump to suck the air from within a hollow copper sphere, establishing perhaps the first high-quality vacuum on Earth. In a theatrical demonstration in 1654,…

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Paul M. Sutter writes: Beginning in the 1970s cosmologists started to uncover the structure of the universe writ large. They already knew that galaxies occasionally clump together into clusters, but over even larger distances, spanning 100 million light-years and more, they found superclusters. And in between those superclusters they saw something even more unexpected: vast regions devoid of galaxies, great and immense dark hollows. The first of these cosmic voids that cosmologists discovered was 65 million light-years across. No theoretical…

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Katie McCormick writes: Perhaps the most famously weird feature of quantum mechanics is nonlocality: Measure one particle in an entangled pair whose partner is miles away, and the measurement seems to rip through the intervening space to instantaneously affect its partner. This “spooky action at a distance” (as Albert Einstein called it) has been the main focus of tests of quantum theory. “Nonlocality is spectacular. I mean, it’s like magic,” said Adán Cabello, a physicist at the University of Seville…

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Science reports: A decade ago, particle physicists thrilled the world. On 4 July 2012, 6000 researchers working with the world’s biggest atom smasher, the Large Hadron Collider (LHC) at the European particle physics laboratory, CERN, announced they had discovered the Higgs boson, a massive, fleeting particle key to their abstruse explanation of how other fundamental particles get their mass. The discovery fulfilled a 45-year-old prediction, completed a theory called the standard model, and thrust physicists into the spotlight. Then came…

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Philip Ball writes: In all of physical law, there’s arguably no principle more sacrosanct than the second law of thermodynamics — the notion that entropy, a measure of disorder, will always stay the same or increase. “If someone points out to you that your pet theory of the universe is in disagreement with Maxwell’s equations — then so much the worse for Maxwell’s equations,” wrote the British astrophysicist Arthur Eddington in his 1928 book The Nature of the Physical World….

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Annaka Harris writes: “I think the flow of time is not part of the fundamental structure of reality,” theoretical physicist Carlo Rovelli tells me. He is currently working on a theory of quantum gravity in which the variable of time plays no part. And throughout our conversation, I’m trying to get my mind around the idea that even though the universe is made up of “events,” as Carlo explains, a single interval between two events can have different values. There…

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Nature reports: One of nuclear physicists’ top wishes is about to come true. After a decades-long wait, a US$942 million accelerator in Michigan is officially inaugurating on 2 May. Its experiments will chart unexplored regions of the landscape of exotic atomic nuclei and shed light on how stars and supernova explosions create most of the elements in the Universe. “This project has been the realization of a dream of the whole community in nuclear physics,” says Ani Aprahamian, an experimental…

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Shutterstock By Sam Baron, Australian Catholic University Does time exist? The answer to this question may seem obvious: of course it does! Just look at a calendar or a clock. But developments in physics suggest the non-existence of time is an open possibility, and one that we should take seriously. How can that be, and what would it mean? It’ll take a little while to explain, but don’t worry: even if time doesn’t exist, our lives will go on as…

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