Physics

Further to Robert Marks on the math paradox that challenges physics because it may be unanswerable, Rob Sheldon writes to say, Without reading the full paper, it sounds like a familiar problem in many-body QM, how do you add up all the distant interactions in an infinite crystal to find the energy of the system at a single point? Sometimes the interactions fade away, and the series converges. Sometimes the interactions stubbornly refuse to fade, and the series diverges. This paper is saying “there is no a-priori way to know if you have a convergent or divergent series.” I think for mathematicians, this is a Thales moment, when they get to tell the physicists that math really does have application Read More ›

From PBS: The ability for seemingly constant things to evolve and change is an important aspect of Einstein’s legacy. If space and time can change, little else is sacred. Modern cosmologists like to contemplate an extreme version of this idea: a multiverse in which the very laws of physics themselves can change from place to place and time to time. Such changes, if they do in fact exist, wouldn’t be arbitrary; like spacetime in general relativity, they would obey very specific equations. So are we now enlisting Einstein on behalf of the multiverse? Out of interest, what would he have thought? We currently have no direct evidence that there is a multiverse, of course. But the possibility is very much Read More ›

From University of Southampton: An international team of physicists has published ground-breaking research on the decay of subatomic particles called kaons – which could change how scientists understand the formation of the universe. Professor Christopher Sachrajda, from the Southampton Theory Astrophysics and Gravity Research Centre at the University of Southampton, has helped to devise the first calculation of how the behaviour of kaons differs when matter is swapped out for antimatter, known as direct “CP” symmetry violation. Should the calculation not match experimental results, it would be conclusive evidence of new, unknown phenomena that lie outside of the Standard Model—physicists’ present understanding of the fundamental particles and the forces between them. The current result, reported in Physical Review Letters, does Read More ›

Why? Didn’t the thing get Higgs a Nobel? Must be more prizes in there somewhere… 😉 Oh well, here: The Higgs was, in a way, the end of the line. At the heart of particle physics is what’s known as the Standard Model: a group of 17 elementary particles and the rules for how they should interact. Up until the Higgs discovery, physicists had observed 16 of these particles—and the field was desperate for a 17th that would push the model in new directions. But the Higgs turned out to be totally ordinary. It acted just like the model said it would act, obeyed every theorized rule. One of physicists’ greatest hopes for the new LHC is to not upend Read More ›

From Nautilus: We want to believe that a thing is somehow more than the sum of its parts. That if we removed an electron’s charge, its mass, its spin, there would be something leftover, a bald electron, a haecceity, as the philosophers say, a primitive thisness. We want to believe that there is something that it means to be this electron rather than that, even if no observation, experiment, or statistic could ever reveal it. We want to believe in a primitive thisness because we want to believe in a primitive ourness—that should we one day meet our double, a perfect clone down to every detail, every dream, utterly indistinguishable to even the most discerning observer, that still there would Read More ›

From Dan Falk at Cosmos: A century ago Einstein sweated blood to give us his mind-bending theory of gravity. As technology caught up, his predictions were verified, one by one. Now only gravitational waves remain. Yet for all its triumphs, general relativity faces a couple of big challenges. Einstein wrestled unsuccessfully with one of them: reconciling the theory with its great nemesis, quantum mechanics. Each theory has been outstanding in its own domain – relativity in the cosmos, quantum mechanics in the subatomic world. But occasionally the domains overlap. To understand the Universe’s earliest moments, as well as the insides of black holes, we still need a theory that bridges the very large and the very small. No one knows Read More ›

From bFast, appended to Baffling but undead physics results: Physicists always seem to end up with puzzles: what is dark energy, what is dark matter, what caused the big bang, how big is a proton. I love the honest puzzles that physicists bring to the table. Evolutionary biologists, however, never seem to be puzzled about nuthin’. First life? Don’t know how yet, but its not a problem. Cambrian explosion, wasn’t mutch,a and it had millions of years. Irreducible complexity? No deal, we did this experiment that produced two mutations to produce a single function — after 1/2 million years worth of evolving. HAR1F pulls off 18 mutations, no problem, millions of years. No issues, not problems, no puzzles. Its as Read More ›

From Nature: When a scientific result seems to show something genuinely new, subsequent experiments are supposed to either confirm it — triggering a textbook rewrite — or show it to be a measurement anomaly or experimental blunder. But some findings seem to remain forever stuck in the middle ground between light and shadow. Here’s one of the six: Diabolical proton discrepancy Given that protons are among the most common and well-studied particles in the Universe, one would expect physicists to have a solid grasp of their size. But in 2010, Randolf Pohl of the Max Planck Institute of Quantum Optics in Garching, Germany, and his team measured the radius of the proton and found it to be 4% smaller than Read More ›

Einstein’s hidden variables tests two ways, closing both loopholes. From the Economist: To save physics from the spooky, Einstein invoked what he called hidden variables (though others might describe them as fiddle factors) that would convey information without breaking the universal speed limit. … By now, most physicists reckon the hidden-variable idea is flawed. But no test had closed both loopholes simultaneously—until this week, that is. Ronald Hanson of the University of Delft and his colleagues, writing in Nature, describe an experiment that starts with two electrons in laboratories separated by more than a kilometre. Each emits a photon that travels down a fibre to a third lab, where the two photons are entangled. That, in turn, entangles the electrons that Read More ›

From big think: MIT Physicist Proposes New “Meaning of Life” MIT physicist Jeremy England claims that life may not be so mysterious after all, despite the fact it is apparently derived from non-living matter. In a new paper, England explains how simple physical laws make complex life more likely than not. In other words, it would be more surprising to find no life in the universe than a buzzing place like planet Earth. Excuse me, but we currently have a sample size of 1. What does all matter—rocks, plants, animals, and humans—have in common? We all absorb and dissipate energy. While a rock absorbs a small amount of energy before releasing what it doesn’t use back into the universe, life Read More ›

Rats. From ScienceDaily: Can the passage of time be measured precisely, always and everywhere? The answer will upset many watchmakers. A team of physicists have just shown that when we are dealing with very large accelerations, no clock will actually be able to show the real passage of time, known as ‘proper time.’ “Our calculations showed that above certain very large accelerations there simply must be time disorders in the decay of elementary particles. And if the disturbances affect fundamental clocks such as muons, then any other device built on the principles of quantum field theory will also be disrupted. Therefore, perfectly precise measurements of proper time are no longer possible. This fact has further consequences, because losing the ability Read More ›

Sounds like science fiction. But from ScienceDaily: New theory of stealth dark matter may explain universe’s missing mass A group of national particle physicists known as the Lattice Strong Dynamics Collaboration, led by a Lawrence Livermore National Laboratory team, has combined theoretical and computational physics techniques and used the Laboratory’s massively parallel 2-petaflop Vulcan supercomputer to devise a new model of dark matter. It identifies it as naturally “stealthy” (i.e. like its namesake aircraft, difficult to detect) today, but would have been easy to see via interactions with ordinary matter in the extremely high-temperature plasma conditions that pervaded the early universe. “These interactions in the early universe are important because ordinary and dark matter abundances today are strikingly similar in Read More ›

Further to the current blaze of nonsense re the multiverse and the unfortunate news that naturalism is dead, at Not Even Wrong, mathematician Peter Woit notes, re Arkani-Harmed, here, A couple years ago I was struck by a talk of his in which he showed a lot of self-knowledge, describing himself as an “ideolog” (see here). There’s more about this in the Quanta profile: “It’s important for me while I’m working on something to be very ideological about it. And then, of course, it’s also important after you are done to forget the ideology and move on to another one.” The ideologies on display this time include a very speculative picture of a future union of mathematics and theoretical physics:More. ‘Nuff Read More ›

Further to “Water’s unique sense of time” (amazing, these accidental freaks of nature,) we also learn, this time from Aeon, about the conundrum of universal constants, like the speed of light: Light travels at around 300,000 km per second. Why not faster? Why not slower? A new theory inches us closer to an answer Electromagnetic theory gave a first crucial insight 150 years ago. The Scottish physicist James Clerk Maxwell showed that when electric and magnetic fields change in time, they interact to produce a travelling electromagnetic wave. Maxwell calculated the speed of the wave from his equations and found it to be exactly the known speed of light. This strongly suggested that light was an electromagnetic wave – as was Read More ›

From ScienceDaily: Using innovative ultrafast vibrational spectroscopies, the researchers show why liquid water is unique when compared to most other molecular liquids. (Actually, usage note: To be unique, water must survive comparison with all other molecular liquids. But let’s get on with the story.) Water is a very special liquid with extremely fast dynamics. Water molecules wiggle and jiggle on sub-picosecond timescales, which make them undistinguishable on this timescale. While the existence of very short-lived local structures — e.g. two water molecules that are very close to one another, or are very far apart from each other — is known to occur, it was commonly believed that they lose the memory of their local structure within less than 0.1 picoseconds. Read More ›