Physics

Sabine Hossenfelder, author of Lost in Math: How Beauty Leads Physics Astray, is not enthusiastic about a new video promoting a new, larger collider for CERN. She believes that current, serious problems are being smoothed over for politicians and the public, by general soothing noises that a bigger collider might answer many questions about our universe. Her summaries are worth reading in detail, for example, Why is there no more antimatter? Because if there was, you wouldn’t be here to ask the question. Presumably this item refers to the baryon asymmetry. This is a fine-tuning problem which simply may not have an answer. And even if it has, the FCC may not answer it. In general, she thinks, That particle physicists Read More ›

From ScienceDaily: Astrophysical evidence suggests that the universe contains a large amount of non-luminous dark matter, yet no definite signal of it has been observed despite concerted efforts by many experimental groups. One exception to this is the long-debated claim by the DArk MAtter (DAMA) collaboration, which has reported positive observations of dark matter in its sodium-iodide detector array. The new COSINE-100 experiment, based at an underground, dark-matter detector at the Yangyang Underground Laboratory in South Korea, has begun to explore DAMA’s claim. It is the first experiment sensitive enough to test DAMA and use the same target material of sodium iodide. COSINE-100 has been recording data since 2016 and now has initial results that challenge the DAMA findings. Those Read More ›

Computer engineering prof Robert J. Marks, first author of Introduction to Evolutionary Informatics, explains, When I was boy, my father explained free will and predestination to me: I dig a fence post hole. · Did I create the hole because of my own free will? · Or was the hole already there and I simply removed the dirt? If true, the hole was predestined. The question cannot be answered by examining the evidence. In philosophy terms, it is “empirically unanswerable.” That is the sort of stuff that philosophers debate. Religious people might point to scripture to support one conclusion over the other. In physics, however, quantum randomness offers a definitive answer to the question of predestination vs. free will—for subatomic Read More ›

In this 2018 video, quantum physicist Anton Zeilinger explains the essence of quantum physics for a general audience: The skinny, courtesy Philip Cunningham: 40 sec: Every object has to be in a definite place is not true anymore… The thought that a particle can be at two places at the same time is (also) not good language. The good language it that there are situations where it is completely undefined where the particle is. (and it is not just us (we ourselves) that don’t know where the particle is, the particle itself does not know where it is). This “nonexistence” is an objective feature of reality… 5:10 min:… superposition is not limited to small systems… 7:35 min:… I have given Read More ›

That’s a common problem when we ask great figures their opinion about things they haven’t studied. From a review of Stephen Hawking’s (1942–2018) last book (or the last book that could be put together plausibly under his name), Brief Answers to the Big Questions: Because of the likelihood of a nuclear confrontation or an environmental catastrophe, we should work out how to leave the planet and colonise space, Hawking reckons. “Spreading out,” he says, “may be the only thing that saves us from ourselves.” He concedes that move will involve abandoning the flora and fauna of Earth, but Hawking seems to believe that humans deserve more of a future than other species. Leaving all other life to fend for itself is Read More ›

Error alone does not apparently explain the discrepancy in these figures: For some methods, which rely on using the light from supernova and pulsing stars called Cepheid variables to determine their changing distance, it appears that objects move away from the Earth 73 kilometers per second faster for every 3.26 million additional light-years, also called a megaparsec. For other measuring methods, which rely on the electromagnetic radiation that reaches us from the early universe called the cosmic microwave background, the value is around 67 kilometers per second per megaparsec. … Most recently, a new result from scientists running the Dark Energy Survey has muddied the waters. Using measurements from supernovae, they in fact measured a Hubble constant of 67.7 kilometers Read More ›

Our physics color commentator, Rob Sheldon, was looking at two physicists’ recent salvos and offers some thoughts: Nicole Yunger Halpern (Theoretical physicist: My field is not going to the dogs vs. The point of view represented by Sabine Hossenfelder (Theoretical physicist: Present phase of physics “not normal” – stagnation, not crisis) and Sarah Scoles (Is cosmology in crisis over how to measure the universe?) Halpern’s response is typical. She’s a young, female, postdoc with jobs at MIT and Harvard. Of course, the future looks bright! Now if it had been a white, male, 40-ish, on his third-postdoc at a 2nd tier school, the story would have been very different. But Halpern is exactly who Sabine Hossenfelder is talking to. What Read More ›

A helpful list of the 11 biggest questions about dark matter starts with this: Originally, some scientists conjectured that the missing mass in the universe was made up of small faint stars and black holes, though detailed observations have not turned up nearly enough such objects to account for dark matter’s influence, as physicist Don Lincoln of the U.S. Department of Energy’s Fermilab previously wrote for Live Science. The current leading contender for dark matter’s mantle is a hypothetical particle called a Weakly Interacting Massive Particle, or WIMP, which would behave sort of like a neutron except would be between 10 and 100 times heavier than a proton, as Lincoln wrote. Yet, this conjecture has only led to more questions… Read More ›

Possibly. They certainly rule out experimenter interference: Quantum particles appear to behave randomly when measured. But what if there is no free will? In that case, the physicists were fated, so to speak, to set up the experiment to achieve a certain set of results which might appear to them to be random. But that was fated too. Koberlein explains, “It’s often said that nothing can travel faster than the speed of light, but it’s really information that can’t travel faster than light. We can send each other telegrams or text messages, but never faster than the time it takes for light to travel between us. In a small lab, light has plenty of time to travel back and forth Read More ›

Proton: stable subatomic particle that has a positive charge equal in magnitude to a unit of electron charge and a rest mass of 1.67262 × 10−27 kg, which is 1,836 times the mass of an electron. (Britannica) Only 9% of the proton’s mass comes from its quarks: The rest of the proton’s mass comes from complicated effects occurring inside the particle, researchers report in the Nov. 23 Physical Review Letters. … Instead, most of the proton’s 938 million electron volts of mass is due to complexities of quantum chromodynamics, or QCD, the theory which accounts for the churning of particles within the proton. Emily Conover, “Physicists finally calculated where the proton’s mass comes from” at Science News These results provide figures for what’s long been suspected. Seems like Read More ›

In recent years, a number of theoretical physicists have raised concerns about stagnation and cool-sounding programs that produce little but TED talks. Now one replies, pointing out that if we leave the wild world of string theory out of the picture, theoretical physicists work with experimentalists more than ever before: In one example, theorists teamed with experimentalists to probe quantum correlations spread across space and time. In another example, theorists posited a mechanism by which superconducting qubits interact with a hot environment. Other illustrations from the past five years include discrete time crystals, many–body scars, magic-angle materials, and quantum chaos. These collaborations even offer hope for steering quantum gravity with experiments. Certain quantum-gravity systems share properties with certain many-particle quantum Read More ›

At her blog, Sabine Hossenfelder, author of Lost in Math: How Beauty Leads Physics Astray, offers a guest post spot to a fellow physicist: No current unified theory includes quantum mechanics fundamentally as part of its structure. But a truly unified theory must. And I believe the ultimate theory will be geometrically natural. Canonical quantum commutation relations are a Lie bracket, which can be part of a Lie group in a geometrically natural description. I fully expect this will lead to a beautiful quantum-unified theory – what I am currently working on. I never expected to find beauty in theoretical physics. I stumbled into it, and into E8 in particular, when looking for a naturally geometric description of fermions. But beauty Read More ›

If you saw it up close? If you were to take a photo of a black hole, what you would see would be akin to a dark shadow in the middle of a glowing fog of light. Hence, we called this feature the shadow of a black hole . Interestingly, the shadow appears larger than you might expect by simply taking the diameter of the event horizon. The reason is simply, that the black hole acts as a giant lens, amplifying itself. Surrounding the shadow will be a thin ‘photon ring’ due to light circling the black hole almost forever. Further out, you would see more rings of light that arise from near the event horizon, but tend to be concentrated Read More ›

Theoretical physicist Sabine Hossenfelder, author of Lost in Math: How Beauty Leads Physics Astray, acknowledges the seriousness of the situation but isn’t sure that the term “crisis” describes the current situation well: I think stagnation describes it better. And let me be clear that the problem with this stagnation is not with the experiments. The problem is loads of wrong predictions from theoretical physicists. The problem is also not that we lack data. We have data in abundance. But all the data are well explained by the existing theories – the standard model of particle physics and the cosmological concordance model. Still, we know that’s not it. The current theories are incomplete. So what would she change? I have spelled out Read More ›