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Physicists finally nail the proton’s size, eliminating an anomaly
- pavel_lishin 7y agoWhat a headline. Should someone talk to the author, make sure they're doing ok?
- draw_down 7y agoFeel free! I don't see the problem with it, though.
- asdfman123 7y agoThe world runs on clicks now, and you have to make headlines sound at least a little outrageous to keep up. I mean, I clicked because I thought, "Hope dies? I'm sure that's an exaggeration..."
- colechristensen 7y agoThere is a certain philosophical dissatisfaction with the standard model and it just keeps getting confirmed over and over, nobody can seem to find any significant new physics because possible discrepancies keep getting eliminated one by one. Hope dies is maybe a bit florid, but it's a bit real if you don't take it too seriously.
- ChuckMcM 7y agoYup, pretty much. Now if they could just use the standard model to explain dark matter/energy or the inconsistencies in the cosmic age evidence, or what ever the non-fundamental physics but really interesting problem is. I wonder if we figure out how to regrow a damaged heart into a healthy heart with a simple injection and 10 weeks of physical therapy if hope will die in all those cardiologists out there who no longer are able to push the boundaries in heart transplant surgery or heart substitutions. What is the effect on people who have spent their lives becoming an expert in a field or subject which now seems to be "done." I could imagine they might lose hope.
- devb 7y agoAuthors don't always have a final say on what the headline will be. Sometimes they don't have any say at all.
- Mathnerd314 7y agoThe original headline is much more positive: http://yfile.news.yorku.ca/2019/09/06/just-how-big-is-a-proton-york-scientists-help-resolve-decade-old-puzzle/ http://yfile.news.yorku.ca/2019/09/06/just-how-big-is-a-prot... I'd say the writer has a tendency to write gloomy headlines: https://www.quantamagazine.org/famous-experiment-dooms-pilot-wave-alternative-to-quantum-weirdness-20181011/ https://www.quantamagazine.org/famous-experiment-dooms-pilot...
- notfashion 7y agoIt's not a case of an "original headline": this is an entirely separate article, not a regurgitation of the press release. Wolchover is a very serious writer. It's pretty sickening to watch the (sadly predictable) HN sneering and mockery around the topic of someone's (anyone's) mental health. It's such a cruel, distorted and completely non-constructive conversation. Do you guys really not have anything more interesting to say?
- Dylan16807 7y agosneering mockery cruel distorted non-constructive You get all this from "make sure they're doing ok?".
- vectorEQ 7y agoso, a failure in measurement sparked a mystery which went on for decades. i wonder how often that happens in science ;P
- RandomTisk 7y agoWorse are the "best explanations" that get adopted as if they were real observations with militant fervor, something we're seeing with Dark Matter and Energy today. It's gotta be difficult to make progress sometimes when most of your field insists that their best theory must be the correct one.
- cthalupa 7y agoPlease. Millions of dollars are spent every year researching alternative theories and modifications to GR that eliminate the need for Dark Matter and Dark Energy. The problem is, and has always been, that these alternative theories are never as accurate or precise as GR and their observational evidence is never as good as what we have for DM and DE. It's not a conspiracy that scientific consensus is that they both exists, and no one is preventing research into alternatives being done. Significantly more money goes into research that accepts their existence, yes, but that's because most scientists do as well. What outcome do you want? To force scientists to work on theories they don't put any stock in? There is still plenty of interest in research papers written by people advancing alternate theories. Good ones are widely read by the entirety of the community, but you make it sound like the scientific community is actively suppressing anyone from researching anything that casts doubt on the existence of dark energy and dark matter, and that's just not true.
- RandomTisk 7y agoIt's not a conspiracy per se, but it fits into a realm where virtually every single documentary about space these days are making overt or not-so-overt claims that it's absolutely real and we're not even considering other possibilities. Of course we are, but that's not how it gets presented by the vast majority of "television physicists" and I find most documentaries about space completely unwatchable these days. Usually it's presented with unwavering faith that dark matter and energy exist, if only we could detect it. The more humble approach would be "95% of the universe is Dark Matter and Energy, unless one of our assumptions is wrong and we just don't know which one yet". That's honesty you just don't find much in media for public consumption, and if it's wrong (I'm not saying it is), then millions of bright minds are being led down the wrong path. I'm just hoping for more honesty about what we actually observe or what we desperately want to observe in popular (scientific) culture.
- Bostonian 7y agoI think in some areas of physics, such as high-energy physics, there is not much left to discover. The Standard Model works. What branches of physics are likely to see progress?
- mfoy_ 7y agoI guess it's hard to say, because we don't know what we don't know. The famous example is Newtonian physics which seemed to perfectly explain everything.... until new tools and methods came out that were capable of showing it break down under extreme circumstances. That's how we ended up with Einsteinian physics, where it accounted for the old model and the new observed discrepancies. So... how do we know that we will not find some bizarre scenario in the future the throws the Standard Model into a similar existential crisis? I say keep your mind open.
- certifiedloud 7y agoEinstein's theory hasn't yet been reconciled with quantum theory. That's a good place to watch for progress.
- willis936 7y agoI wonder if there is a Future Circular Collider that could help expand the standard model into this regime.
- sousavdouglas 7y agoNo
- gbear605 7y agoThere unfortunately isn't, at least not at a scale that's feasible right now. [0] [0]: http://backreaction.blogspot.com/2019/03/nonsense-arguments-for-building-bigger.html http://backreaction.blogspot.com/2019/03/nonsense-arguments-...
- 7y ago
- conistonwater 7y ago> If the discrepancy was real, meaning protons really shrink in the presence of muons, this would imply unknown physical interactions between protons and muons — a fundamental discovery. Hundreds of papers speculating about the possibility have been written in the near-decade since. This reminds me of a joke. An experimental physicist walks into a theoretical physicist's office with a really cool experimental result, shows the printed out graph to the theoretician. He thinks for a while and says, "this is perfectly in line with theory, let me explain how". The experimentalist looks at the graph, scratches his head, says "uh, this is upside down", and rotates the paper 180 degrees. The theoretician thinks a while more and says, "well this can also be explained".
- WhitneyLand 7y agoThe clever thing about these kinds of jokes as when it happens in politics is, they manage to mock two groups of people such that each group reads the joke and tends to laugh because they infer it as poking fun at the other group.
- AnthonBerg 7y agoWe laugh even if it is rotated by 180 degrees.
- charles_f 7y agoReminds me of a person on HN that was telling a joke on a specific group of people, and another person came and said "that can be laughed about", and the initial person said "actually it's about all groups of people", and the other person said "that can also be laughed about".
- raldi 7y agoThis was a great writeup. Accessible, yet I feel like I learned some genuine not-dumbed-down science.
- FuckButtons 7y agoQuanta has a lot of good articles like this one, definitely worth looking at every now and then.
- ur-whale 7y agoI wish a physicist could explain here how the very notion of "diameter" has any meaning for an object whose size (IIUC) belong entirely to the quantum realm. Is the hydrogen atom two hard little balls of matter orbiting one another, as we were taught in primary school, or are they a probabilistic soup with various, vaguely localized extrema? If the latter, how do you even define the notion of diameter?
- BurningFrog 7y agoThey're a soup. I suppose you have to pick a probability criteria for the diameter.
- whatshisface 7y agoUsually the radius of something like a proton or an atom takes the form of a parameter in an equation that just-so-happens to be measured in a unit of length. It's not defined specifically to be an indication of the extent of the particle, it just happens to roughly be about the right size. This paper[0] says that it is defined in terms of a "probability amplitude that an interaction between a photon of four-momentum q^μ (Q2=−q2) and a charged constituent of the proton can absorb such a momentum with the proton remaining in its ground state." So, not exactly a radius, but "radius" is an okay conceptual mnemonic. [0] https://arxiv.org/pdf/1812.02714.pdf https://arxiv.org/pdf/1812.02714.pdf
- lisper 7y agoThat is an excellent question! The definition is somewhat arbitrary, but still has some real physical significance. In actual fact, a proton is a field, so it doesn't have sharp boundaries. But the amplitude of the field still dies off very rapidly with distance from the center, so you can pick some arbitrary small value and say "the point at which the amplitude becomes less than this value is the radius of the proton". What matters is not really the number that you get out of this, but the fact that the experimental results of measuring this value appeared to change in the presence of muons. This was a phenomenon that was not predicted by present theory, and if it had held up, would have been a major breakthrough. One of the biggest problems in physics right now is that there are no experiments (except possibly this one) whose results are at odds with the Standard Model. That makes it hard to improve the model!
- deleted 7y ago[deleted]
- jpmattia 7y agoProbably worth noting: The author writes the article as though the latest experiment "solves" the issue. A more nuanced description (which is not exactly quantamagazine's forte) would note there is a conundrum about the proton size. The article describes a measurement that falls under "spectroscopic methods" in the wiki [1]. Why eg scattering measurements should yield a different value is not at all clear. [1] https://en.wikipedia.org/wiki/Proton_radius_puzzle https://en.wikipedia.org/wiki/Proton_radius_puzzle
- fsh 7y agoThe article doesn't mention that since 2010 two more measurements on atomic hydrogen that determine the proton size with similar accuracy have been published. The first one (https://science.sciencemag.org/content/358/6359/79 https://science.sciencemag.org/content/358/6359/79) agrees well with the muonic value, while the second one (https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.120.183001 https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.12...) disagrees with the muonic value and agrees with the old, larger value.
- davrosthedalek 7y agoYes, very true. I think it's a shame that some people just declare victory and ignore the discrepancy in these modern experiments. At the same time, a similar split seems to happen using the scattering method, but the data are not published yet. The results from Hessels were announced as preliminary results more than a year ago -- it's great that they are finally out peer-reviewed. But the community at large didn't stop back then when the results came out, with more experiments planned all over the world, especially but not only in the scattering sector. We made progress, but the puzzle isn't dead yet. There is actually a conference starting next week on this topic: http://ecsac.ictp.it/ecsac19/ http://ecsac.ictp.it/ecsac19/ It's a rare occasion where nuclear physics and AMO overlap. Another one is the Zemach radius, which also requires knowledge of the proton magnetic form factor.
- fastaguy88 7y agoOne has to wonder why the original "muon" paper, which produced such controversial results, did not include the control of measuring with the same methods conventional ("electron") hydrogen. Doing the control would have cleared things up a lot sooner.
- fsh 7y agoIt took Eric Hessel's group eight years of hard work to do the measurement in electronic hydrogen. The experiments are completely different.
- dschuetz 7y agoI don't understand how physicists cannot see the obvious: the size of a proton appears not to have a fixed/natural value. It seems to depend on the quantum state of their system, energy levels, and the coupling partner's quantum state, energy levels and mass. "Physicists finally nail..." sounds like a part of a joke: "Physicists finally nail the coffin with the research funds shut"