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The Proton Just Got Smaller 289

inflame writes "A new paper published in Nature has said that the proton may be smaller than we previously thought. The article states 'The difference is so infinitesimal that it might defy belief that anyone, even physicists, would care. But the new measurements could mean that there is a gap in existing theories of quantum mechanics. "It's a very serious discrepancy," says Ingo Sick, a physicist at the University of Basel in Switzerland, who has tried to reconcile the finding with four decades of previous measurements. "There is really something seriously wrong someplace."' Would this indicate new physics if proven?"
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The Proton Just Got Smaller

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  • by Remus Shepherd ( 32833 ) <> on Thursday July 08, 2010 @12:44PM (#32841604) Homepage

    Physicist here.

    What's the diameter of the earth's magnetosphere?

    About 10 Earth radii, defined as the point where the Earth's magnetic field is stronger than the solar wind and thus becomes the dominant force on electrical particles.

    Similarly, we define the proton's radius in terms of its charge distribution. See how easy that is? It only takes a simple definition to make a word like 'size' meaningful.

    And in the case of the proton is *is* meaningful, because you are incorrect about the proton being a singularity. The proton is composed of three quarks, each with their own charges and charge fields.

    The quarks inside a proton are held together by strong force interactions. So any change in the measurable size of a proton is a change in what we know about the strong force. This is significant. Either the strong force is 4% stronger than our calculations predict, or there is another mechanism that is squeezing that proton's charge field down. Another force? Another particle? It'll be exciting to find out, now that we know there's something there to find.

    The journalists who write about science often use bad, confusing, or just plain nonsensical terms. But it's almost always the journalists, and you can't really fault them for dumbing down their story to appeal to the largest group of readers. Whatever you do, don't blame the scientists. They are doing good work. It's not their fault if journalists relate it improperly, nor is it the scientists' fault if you don't understand the explanations.

  • Re:Ummm... (Score:3, Informative)

    by painandgreed ( 692585 ) on Thursday July 08, 2010 @01:16PM (#32842066)

    According to the article the difference is 4%. How is that small? I'm not even a physicist and that seems like a pretty huge difference to me.

    It is a significant difference, however, this is Nature magazine and does not usually deal with data or presenting it to scientists but rather the common person. This can be seen by their writing out "0.00000000000003 millimetres" rather than the more usually useful "3*10^-16 m". The people reading their article are not actually intended to make sense out of that number. Rather they are just supposed to see all the zeros and go "Wow, that's really, really small and insignificant." Nature is not actually trying to present data but provide a combination of sensational, yet easily understandable reporting to the layperson who has some interest in science but doesn't really care to use any of it.

  • by Anonymous Coward on Thursday July 08, 2010 @02:22PM (#32842952)

    Nope. It's still a fallacy of the form "John is an expert, John says X is true, therefore X is true." What if both John and Jane are experts, yet Jane says that NOT X is true. Which of the experts is correct? And that is precisely the situation. So, you don't have to be an expert to have an opinion on the matter, especially considering that the experts themselves get it wrong sometimes. You merely weigh the opinion accordingly.

    Also, you commit the fallacy of ad hominem. Have a nice day.

  • Re:Ummm... (Score:4, Informative)

    by cowscows ( 103644 ) on Thursday July 08, 2010 @03:37PM (#32843724) Journal

    Even the heaviest of elements that you might come across here on earth are mostly empty space down on the atomic level. That's why it's possible for a teaspoon's volume worth of neutron star to contain millions of tons of mass. The ridiculous amount of gravity there has overcome some of the forces that give atoms their structure and squeezed out a bunch of that empty space.

    The universe is a crazy place.

  • Re:Anonymous Coward. (Score:4, Informative)

    by Artifakt ( 700173 ) on Thursday July 08, 2010 @03:40PM (#32843756)

    Godel's theorem applies to mathematical formal systems that are sufficiently complex and powerful. 'Sufficiently' here is reached by formal systems far, far simpler and less powerful than the real number system. The only way Godel's theorem wouldn't apply to our models of the universe is if all the calculations used in all related physics could be encoded in a system much simpler than first year algebra or trig. You might get around it if you could describe all physics using only formulae that cannot under any circumstances what-so-ever generate an irrational number or any undefined value, that never require infinitesimals or infinities, and that can't even imply a potential need for imaginary numbers. Yes, Godel's theorem is that powerful.

  • Re:Anonymous Coward. (Score:3, Informative)

    by lgw ( 121541 ) on Thursday July 08, 2010 @06:12PM (#32845238) Journal

    Here are two systems to which Godel's problem does not apply:

    1. The system of math of all integers less than Graham's number (a number large even by size-of-the-universe standards).
    2. The system of non-computable reals (infinitely long "decimals" without a pattern), as might be correct for time and distance measurements.

    Similarly, the halting problem doesn't apply to any computer you can actually build, but only to a computer with infinite memory. As long as you're dealing with finite sets, or purely infinite sets (no finite integers allowed), you don't have the problem. Imaginary numbers are fine IIRC, if composed of bounded finite integers (not sure what you'd use a system like that for). A system like imaginary numbers except with triplets has no trouble with Godel (because it's surprisingly weak - you can't make a field IIRC, and this is partly why theres no 2D solution to the wave equation).

    Even so, I'm not sure how much physics you could do before Godel's Theorum became an issue - these example systems are more restrictive than they might appear. On the other hand, a lot of work has been done to show how powerful Godel's Theorum ism but relitively little to explore how useful of a system one might construct without it being a problem.

  • Re:Ummm... (Score:3, Informative)

    by TimboJones ( 192691 ) <> on Friday July 09, 2010 @03:18AM (#32848152) Homepage

    Solidity isn't a measure of molecular or atomic density, of how much of an object's actual volume is 'matter' as opposed to empty space. It's a measure of the arrangement of those molecules and their resistance to change in that arrangement.

    Solidity could be thought of as a resistive force being provided as an aggregate of the energy bonds between atoms & the arrangement of and repulsive force between adjacent molecules. In particular therefore, measurement of solidity is dependent on the size and force of the measurement device.

    This table in front of me is solid relative to my hand as I push on it. It's not solid relative to an object small enough to slip between the wood grain, such as perhaps a gamma ray photon. It's also not solid relative to an ax or sledge swung at high velocity, at least not at the time and location of impact.

Always leave room to add an explanation if it doesn't work out.