Cosmology

From Adam Hadhazy at Space.com: A new cosmic map was unveiled in August, plotting where the mysterious substance called dark matter is clumped across the universe. To immense relief — and frustration — the map is just what scientists had expected. The distribution of dark matter agrees with our current understanding of a universe born with certain properties in a Big Bang, 13.8 billion years ago. So what is the problem here? But for all the map’s confirmatory power, it still tells us little about the true identity of dark matter, which acts as an invisible scaffold for galaxies and cosmic structure. It also does not explain an even bigger factor shaping the cosmos, known as dark energy, an enigmatic Read More ›

Whatever dark matter is, is not what was expected. From Dan Hooper at Physics: The latest results from two dark matter searches have further ruled out many theoretically attractive dark matter particle candidates. The lack of a definitive detection of dark matter particles, in both underground experiments and at the Large Hadron Collider [4–7], has had a palpable effect on the community of scientists that study particle dark matter. Even though a discovery could very plausibly be right around the corner, there is a widespread view that many of the most theoretically attractive candidates for dark matter should have been detected by now, based on their predicted properties. In the absence of such a discovery, the field has begun to Read More ›

No help for materialism. – Reflecting light off satellite backs up Wheeler’s quantum theory thought experiment – October 26, 2017 – Bob Yirka: Excerpt: Back in the late 1970s, physicist Johan Wheeler tossed around a thought experiment in which he asked what would happen if tests allowed researchers to change parameters after a photon was fired, but before it had reached a sensor for testing—would it somehow alter its behavior mid-course? He also considered the possibilities as light from a distant quasar made its way through space, being lensed by gravity. Was it possible that the light could somehow choose to behave as a wave or a particle depending on what scientists here on Earth did in trying to measure Read More ›

From Andrew Griffin at The Independent: “All of our observations find a complete symmetry between matter and antimatter, which is why the universe should not actually exist,” explained Christian Smorra, the author of a new study conducted at CERN. “An asymmetry must exist here somewhere but we simply do not understand where the difference is. What is the source of the symmetry break?” The latest possibility was matter and anti-matter’s different magnetism. But new research shows that they are identical in that way too – lending further mystery to the question of why the universe is still around at all. More. Persons who find that this situation seriously interferes with their lifestyle could try complaining to the UN. See also: Read More ›

From philosopher Emily Thomas at The Conversation: Is there space between the stars? The relationist Leibniz argued that space is the spatial relations between things. Australia is “south of” Singapore. The tree is “three meters left of” the bush. Sean Spicer is “behind” the bush. That means space would not exist independently of the things it connects. For Leibniz, if nothing existed, there couldn’t be any spatial relations. If our universe were destroyed, space would not exist. In contrast, the absolutist Clarke argued that space is a sort of substance that is everywhere. Space is a giant container, containing all the things in the universe: stars, planets, us. Space allows us to make sense of how things move from one Read More ›

From Shannon Palus at New Scientist: THERE is a hole in the sun. Right in the middle, a mass the size of 1500 Earths has simply disappeared. Much of what we know about the sun’s behaviour says it should be there – but when we interpret the data encoded in sunlight, that chunk of stuff is nowhere to be seen. That has shaken up our understanding of how the sun works, and physicists are struggling to figure out what fills that hole. It could be a thing, like dark matter. It could be a concept, with elements such as carbon and nitrogen simply behaving in a way we didn’t expect under crushing pressure. Or perhaps we’re looking at the sun Read More ›

From Cathay O’Connell at at Cosmos: Like me, physicists around the world are in the midst of an important search that has so far proven fruitless. Their quarry is nothing less than most of the matter in the universe, so-called “dark matter”. So far their most sensitive detectors have found – to be pithy – nada. Despite the lack of results, scientists aren’t giving up. “The frequency with which articles show up in the popular press saying ‘maybe dark matter isn’t real’ massively exceeds the frequency with which physicists or astronomers find any reason to re-examine that question,” says Katie Mack, a theoretical astrophysicist at the University of Melbourne. In many respects, the quest for dark matter has only just Read More ›

From Sabine Hossenfelder at her blog Backreaction: I’ve had many interesting reactions to my recent post about inflation, this idea that the early universe expanded exponentially and thereby flattened and smoothed itself. The maybe most interesting response to my pointing out that inflation doesn’t solve the problems it was invented to solve is a flabbergasted: “But everyone else says it does.” … I’m not sure why that is so. Those who I personally speak with pretty quickly agree that what I say is correct. The math isn’t all that difficult and the situation pretty clar. The puzzle is, why then do so many of them tell a story that is nonsense? And why do they keep teaching it to students, Read More ›

From astrophysicist Ethan Siegel at Forbes: The multiverse is inevitable and we’re living in it What is the Multiverse, then? It may go well beyond physics, and be the first physically motivated “metaphysics” we’ve ever encountered. For the first time, we’re understanding the limits of what our Universe can teach us. There is information we need, but that we’ll never obtain, in order to elevate this into the realm of testable science. Until then, we can predict, but neither verify nor refute, the fact that our Universe is just one small part of a far grander realm: the Multiverse. More. In other words, the multiverse is to be accepted as science, even though it may never be testable, thus never Read More ›

Recently, we reported on the question of whether the missing dark matter of the universe has finally been found, and we cautioned, Keep the file open but remember: We did find the Higgs boson (and Peter Higgs got the Nobel). But gravitational waves and dark energy are questionable despite the Nobels awarded. More. Our physics commentator Rob Sheldon offers some perspective: The New Scientist was kind enough to link to the arXiv server, so I could read the actual paper. Because the journalese is not making the slightest bit of sense. The two main conundrums of dark matter are: a) It allows galaxies to spin faster than they otherwise would, yet not enough gas is found in the galaxies to Read More ›

In the view of physicist Ethan Siegel at Forbes, the doomed ideas are proton decay, modified gravity, supersymmetry, Technicolor, and WIMP-based dark matter. Supersymmetry is, of course, Cool, so it is immortal, irrespective of evidence. But Siegel cautions, While there are many elegant reasons to favor supersymmetry, the fact is that these particles should exist at approximately the same masses as the highest-mass Standard Model particles. With the advent of the LHC, we have determined that if these particles exist, they are many times heavier than the Standard Model particles, so much so that they would no longer solve the mass-difference problem. As a theory to explain this hierarchy problem, supersymmetry is completely dead. More. Of course, it might be Read More ›

According to a report from Leah Crane at New Scientist: The missing links between galaxies have finally been found. This is the first detection of the roughly half of the normal matter in our universe – protons, neutrons and electrons – unaccounted for by previous observations of stars, galaxies and other bright objects in space. Two separate teams found the missing matter – made of particles called baryons rather than dark matter – linking galaxies together through filaments of hot, diffuse gas. Two separate teams found the missing matter – made of particles called baryons rather than dark matter – linking galaxies together through filaments of hot, diffuse gas. … Because the gas is so tenuous and not quite hot Read More ›

Here. Paper. See also: Carlo Rovelli: Theories of everything ill-conceived but we can learn to understand quantum mechanics

From Oxford’s William E. Carroll at Big Questions Online: The use of cosmology either to deny or to affirm creation is often the result of confusions about what creation is and about the explanatory power of the natural sciences. Creation, as a metaphysical and theological notion, affirms that all that exists — in whatever way it does — depends upon God as a cause. The natural sciences have as their subject the world of changing things, from subatomic particles to acorns to galaxies. Whenever there is a change there must be something that changes. Whether these changes are biological or cosmological, without beginning or end, or temporally finite, they are still processes. Creation, on the other hand, is the radical Read More ›

From Rachel Feltman and Matthew R. Francis at Popular Science: The main reason some physicists obsess over the beginning of the universe is because so much evidence points to there being one. But what if our universe grooved within an ageless multiverse—like a patch of ground from which countless flowers bloom. In this model, each universe has a big bang and keeps its own time. In the most popular version, each universe might even have its own version of physics too. Infinite possibilities yield infinite results: Some say this theory explains life itself. We’d have to be extremely lucky for a single big bang to create a universe with the perfect conditions for life as we know it, but if Read More ›