7 ms·

Yes, sure, they've measured something surprising. I have no reason to doubt that. A few years ago, the enormously more respected folks at the OPERA experiment

• ngoldbaum 11y ago
  This reminds me of the story behind the "discovery" of cold fusion in the 80s. Sure, Pons & Fleischman may have thought they measured something, but in the end the whole effect could be attributed to careless experimental design and procedure. See this paper: http://pus.sagepub.com/content/5/2/121.short http://pus.sagepub.com/content/5/2/121.short (unfortunately behind a paywall)
  • tzs 11y ago
    Cold fusion is a bit more complicated than that. The early experiments were certainly flawed, and there were way to many people announcing results for publicity before they had checked their work. After a few years, it was no longer socially acceptable for respected scientists to work on cold fusion. It didn't matter anymore how good your reputation was as a researcher, or how carefully designed your experiment was--if your research was in cold fusion, it would get largely ignored. Unfortunately, this happened around the time a couple groups of respected researchers with good experiment design were getting interesting results pointing to real new phenomena, and perhaps explaining why prior results had been so erratic. David Goodstein around this time wrote a great article [1] looking back at cold fusion, which included a discussion of these later results, and how socially science had reached a state where they could not be considered. Here are the last few paragraphs. All of this was much less important than the fact that Cold Fusion experiments, if they gave positive results at all, gave them only sporadically and unpredictably. When Bednorz and Mueller announced the discovery of high-temperature superconductivity in 1986, no one carped about control experiments, because, once the recipe was known, any competent scientist could make a sample and test it and it would work immediately. If, at their press conference, Pons and Fleischmann had given a dependable recipe for producing excess heat, they very likely would be Nobel Prizewinners now (as Bednorz and Mueller are) rather than social outcasts from the community of scientists. The essential key to the return of Cold Fusion to scientific respectability is to find the missing ingredient that would make the recipe work every time. Experiments done in the U.S. and in Japan, and reported at the Maui meeting indicate that the missing ingredient may have been found. In all the various Cold Fusion experiments, the first step is to load deuterium into the body of metallic palladium. The issue is how much deuterium gets into the metal. The ratio of the number of atoms of deuterium in the metal to the number of atoms of palladium is called x. It turns out, by means of electrolysis, or by putting the metal in deuterium gas, that it is rather easy to get x up to the range of about 0.6 or 0.7. That is already a startlingly high figure. If there are almost as many deuterium atoms as palladium atoms in the material, the density of deuterium (a form of hydrogen) is essentially equal to that of liquid hydrogen rocket fuel, which can ordinarily exist only at extreme low temperatures. In other words, palladium (and certain other metals including titanium) soak up almost unbelievable amounts of hydrogen or deuterium if given the chance. This is far from a new discovery. However, according to the experiments reported at Maui, x=0.6 or 0.7 is not enough to produce Cold Fusion. Both the American and Japanese groups showed data indicating there is a sharp threshold at x=0.85. Below that value (which can only be reached with great difficulty and under favorable circumstances) excess heat is never observed. But, once x gets above that value, excess heat is essentially always observed, according to the reports presented at Maui, and recounted by Franco Scaramuzzi in his seminar at the University of Rome. The audience at Rome, certainly the senior professors who were present, listened politely, but they did not hear what Franco was saying (that much became clear from the questions that were asked at the end of the seminar, and comments that were made afterward). If they went away with any lasting impression at all, it was just the sad realization that a fine scientist like Franco had not yet given up his obsession with Cold Fusion. They cannot be blamed. Any other audience of mainstream scientists would have reacted exactly the same way. If Cold Fusion ever gains back the scientific respectability that was squandered in March and April of 1989, it will be the result of a long, difficult battle that has barely begun. Recently, I told this story in a Philosophy course we teach at Caltech called "Ethics of Research." The first question, when I finished my tale, was, do I believe in Cold Fusion? The answer is, no. Certainly, I believe quite firmly the theoretical arguments that say Cold Fusion is impossible. On the other hand, however, I believe equally firmly in the integrity and competence of Franco Scaramuzzi and his group of co-workers at Frascati. I was disturbed when I saw that Franco had gotten caught in the web of science-by-news conference in April 1989 (although I was truly pleased that he finally got the long overdue recognition his agency ENEA owed him), and I was even more distressed when I learned that Franco and his group had observed excess heat (the "bad kind" of Cold Fusion). However, I have looked at their cells, and looked at their data, and it's all pretty impressive. The Japanese experiment showing that heat nearly always results when x is greater than 0.85 looks even more impressive on paper. It seems a particularly elegant, well designed experiment, at least to the untutored eye of a physicist (what do I know about electrochemistry?) What all these experiments really need is critical examination by accomplished rivals intent on proving them wrong. That is part of the normal functioning of science. Unfortunately, in this area, science is not functioning normally. There is nobody out there listening. I suppose that, if nuclear fusion really does take place whenever x is greater than 0.85 in palladium, the world of conventional science will eventually be forced to take notice. If not, then the whole story I have told you is nothing but a curious footnote to a bizarre and ugly episode in the history of science. Either way, I think the story illuminates the inner dynamics of the scientific enterprise in a way that few other stories have done. For that reason alone, it may be worth telling. [1] http://www.its.caltech.edu/~dg/fusion_art.html http://www.its.caltech.edu/~dg/fusion_art.html
  • Animats 11y ago
    That was taken very seriously at the time. I went to a well-attended talk at Stanford by a Stanford physicist who was trying to replicate the Pons/Fleischman experiment. When they first set up the apparatus, they had radiation detectors with alarms, in case it started generating a dangerous level of neutrons. After some initial tests where not much happened, they moved the radiation alarm gear back a bit. Total measured neutron output, best case, appeared to be twice background. That's small enough that people moving around (people are mostly water) was enough to cause such variation. So they moved the experiment to a "neutron cube", a big box built of lead bricks where few background neutrons penetrated. Then there was no significant difference in neutron levels between "off" and "on". They also tried heat generation measurement. Because you have to put power into the Pons/Fleischman apparatus to get anything to happen (it's not self-sustaining) it's a difficult experiment to do accurately. It requires water jackets, insulation, and lots of measurements. They were unable to detect any heat output above measurement noise.
• lotsofmangos 11y ago
  That was one experimental setup, that was not replicated by other experiments though. It is a bit different when you get multiple experiments by lots of different teams.
• spott 11y ago
  So, it is worth bringing up: GR doesn't require global conservation of momentum or energy.[0,1] I'm not saying anything about the experiment, but I think your statement that "conservation of momentum is more deeply embedded..." isn't quite so accurate. [0] http://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/ http://www.preposterousuniverse.com/blog/2010/02/22/energy-i... [1] http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_g...
  • Steuard 11y ago
    Yes, it would be more precise if I had prepended "local" every time I said "conservation of momentum" above. With that clarification, I'm happy to stand by what I've said.
    • 3iak 11y ago
      "local" seems like a fairly large assumption for something hypothesized by at least some to work through quantum mechanics, of which a central tenant is non-locality. In fact, given the consistency of qm experimental results over the past 50 or so years, it seems entirely plausible to think that it would be a field of study which could upend classical physics. All that being said I agree extreme skepticism is healthy here, though arrogance or dismissal doesn't seem quite appropriate as these results continue to be reproduced.
      • Steuard 11y ago
        I may have been using a technical term too glibly there. Local conservation of momentum is a fundamental property of any translation-invariant model in the framework of quantum field theory. All this means is that the (vector) momentum flowing into any point in space-time must equal the momentum flowing out plus any increase in "stored" momentum at that point (whatever that might mean). Quantum mechanics is a "local" theory in the formal sense, at least in any halfway mainstream formulation (from Copenhagen to many-worlds). Even the "spooky action at a distance" that folks talk about in reference to quantum phenomena is never capable of transmitting information outside of the "cone of causality" in space-time (which is the "light cone" in most relativistic theories: information can't travel faster than light).
• alextgordon 11y ago
  Happens the other way too. In the 80s high-temperature superconductors were discovered, which were 'impossible' by previous understanding. The theory is still catching up to that.
  • Steuard 11y ago
    And even low-Tc superconductors looked "impossible" under the physics of their day. No question about it! Science thrives on surprises: it's the very best part of what we do. But maybe non-physicists don't have a sense of the range of meanings that "that isn't possible within current theory" can have. High-Tc might have been "impossible" under basic BCS superconductivity theory, but BCS theory itself taught us that it was possible to find novel theoretical mechanisms generating zero resistance, so needing a new one was surprising but not unprecedented. "Standard" low-Tc superconductivity appeared "impossible" under the usual models of materials' resistivity, but even that was merely a violation of a well-tested model when it was extended to a previously untested very-low-temperature regime. Resolving that apparent impossibility didn't require rewriting any fundamental principles, it just required very careful application of the existing theoretical framework. These speculative new propulsion theories appear to violate the conservation laws underlying all of our existing models of physics, and in an experimental regime of size/temperature/etc. where (I believe) they have been very well-tested in the past. Any calculation within the framework of quantum field theory or general relativity will inevitably result in momentum being (locally) conserved: it's unavoidably built in to the formalism. So as I said to begin with, although it's obviously not truly impossible that some entirely different framework could turn out to be correct, that is an enormously bigger jump than any stage of the discovery and explanation of superconductivity.
    • gus_massa 11y ago
      I agree completely. I´ll try to explain this with a simpler example. A long time ago, people thought that the faster than sound planes were impossible, perhaps some wrote that formally. The materials didn't have enough strength, it would become too hot, the pressure at some point would be too high, ... To model a faster than sound plane you need to model a lot of complicated interactions between a lot of atoms, and then you need some simplifications, and with the simplifications used at that time it was impossible. The conservation of momentum is a very low level result, so you don't need to put a lot of simplifications to prove it or measure it. For example you can measure the conservation of momentum when a photon hits an electron almost directly: http://en.wikipedia.org/wiki/Compton_scattering http://en.wikipedia.org/wiki/Compton_scattering
• SEJeff 11y ago
  For the longest time, everyone thought that the earth was flat as well until this heretic said, nope it is flat. Challenging group think and being skeptical is part of being a proper scientist. Perhaps they end up learning something entirely new from all of this.
  • knodi123 11y ago
    Interesting side note, it wasn't thought to be flat for as long as most people think. The roundness of earth is a pretty ancient piece of knowledge. https://en.wikipedia.org/wiki/Myth_of_the_Flat_Earth https://en.wikipedia.org/wiki/Myth_of_the_Flat_Earth
  • lotsofmangos 11y ago
    Go read up on Eratosthenes. http://en.wikipedia.org/wiki/Eratosthenes http://en.wikipedia.org/wiki/Eratosthenes
  • teraflop 11y ago
    Which "heretic" would you be referring to? Pythagoras? He was persecuted, but not for believing in a spherical earth.
  • bjourne 11y ago
    The heretic, Galileo Galilei, claimed that the earth revolved around the sun instead of the sun revolving around the earth. That the earth is (almost) spherical was known since antiquity.
    • danielweber 11y ago
      I thought his name was Copernicus.
      • btilly 11y ago
        Copernicus came up with the theory. Galileo became a heretic for how he popularized it.
• zamalek 11y ago
  The neutrino phenomenon was caused by a calculation error regarding GR and was miniscule magnitudes of error. I'm genuinely curious how a measurable force is a calculation error. Notwithstanding that whether or not it can be explained it works. The measured forces are so substantial that even a high school student with high school apparatus would notice them, it's hardly caused by a wobbly cable in precision equipment.
• tonyhb 11y ago
  This doesn't have to violate conservation of momentum to work. We don't understand how it works yet, which precludes us from saying that it violates our current understanding of physics. I'm no physicist but this guy[1] is, and his paper — which is based off of research with evidence backing it up in the 1970's — suggests that the EmDrive creates propulsion from Unruh radiation[2]. [1]http://physicsfromtheedge.blogspot.co.uk/2015/04/light-in-box-emdrive.html http://physicsfromtheedge.blogspot.co.uk/2015/04/light-in-bo... [2]http://www.ptep-online.com/index_files/2015/PP-40-15.PDF http://www.ptep-online.com/index_files/2015/PP-40-15.PDF
  • gus_massa 11y ago
    If this is consistent with quantum mechanics, this must emit some kind of particles, the main candidates are photons (and far less probable gravitons, but some alternatives / variations claim to use gravity). (I'm not sure about Unruh radiation, but the nice thing about radiation is that when you see it far enough, it doesn't depend on the details of the source, it's simple a bunch of photons. (Well, the color of the photon depends on the details of the source, but they are undistinguishable from other photons.)) If this is consistent with special relativity, and the particles are mass less, then the Force/Power ratio is at most 1/c, that is 0.0033 uN/W = 0.0033 mN/KW. If the particles are not mass less, and you just create them at the moment to emit them, the ratio is even smaller, much smaller. If the particles are not mass less, and just accelerate them from a reservoir, the ratio can be much bigger, but now you have a standard rocket, not a fuel-less rocket. Someone compiled here a list of experiments, with the Force/Power ratio: http://forum.nasaspaceflight.com/index.php?topic=36313.msg1302455#msg1302455 http://forum.nasaspaceflight.com/index.php?topic=36313.msg13... They vary from 3x to 200000x the theoretical maximum if we assume that this doesn't break the conservation of momentum, special relativity and quantum mechanics. (Perhaps it's not necessary to use quantum mechanics, because the classical electromagnetic waves have the same Force/Power ratio, because they are actually a good approximation of the quantum electromagnetic waves. But the photons picture makes all clearer.)
  • pdonis 11y ago
    > the EmDrive creates propulsion from Unruh radiation This would just be a standard photon rocket--the cavity would eject photons out one end and move in the other direction. AFAIK all the EmDrive experimenters are claiming that no radiation is coming out of the cavity.
• Dylan16807 11y ago
  >Despite this coming from a large group of scientists with top-notch credentials, that was immediately doubted by almost the entire physics community You make it sound like the scientists reporting it didn't doubt it.
  • Steuard 11y ago
    Well, that's a funny question, right? On the one hand, they really were careful in their announcement to indicate "we're not sure about this". They were clearly making a real attempt to exercise proper scientific skepticism of such a remarkable result. But on the other hand, they were willing to make that public announcement in the first place. If they'd really felt the same level of skepticism that most of the rest of the community did, they might have done the tests that eventually found that loose cable before they stuck their necks out. (But then, part of their intent was clearly to get help and suggestions in figuring out what the lingering errors might be, and to get broader input on how feasible superluminal neutrinos might be theoretically. I can't judge them too harshly, even if they did wind up looking a step or two more willing to believe than they should have been.)
    • Dylan16807 11y ago
      At the time I saw it as a big request for help in finding the experimental oversight. They had tried pretty hard to rule everything out, and they wanted fresh eyes.
• cowkingdeluxe 11y ago
  This statement is extremely dishonest and inaccurate. The folks at the OPERA experiment stated that they found something that needed further testing. They even said that they doubted faster than light particles. They wanted their experiment audited and repeated and stated that they wanted help from the scientific community. The media is who turned it into a circus.