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What Is A Particle?

posted by Fnord666 on Wednesday November 18 2020, @01:38PM   Printer-friendly
from the left-as-an-exercise-to-the-reader dept.

Common Joe writes:

What Is A Particle?

Given that everything in the universe reduces to particles, a question presents itself: What are particles?

The easy answer quickly shows itself to be unsatisfying. Namely, electrons, photons, quarks and other "fundamental" particles supposedly lack substructure or physical extent. "We basically think of a particle as a pointlike object," said Mary Gaillard, a particle theorist at the University of California, Berkeley who predicted the masses of two types of quarks in the 1970s. And yet particles have distinct traits, such as charge and mass. How can a dimensionless point bear weight?

"We say they are 'fundamental,'" said Xiao-Gang Wen, a theoretical physicist at the Massachusetts Institute of Technology. "But that's just a [way to say] to students, 'Don't ask! I don't know the answer. It's fundamental; don't ask anymore.'"

It's a good "average Joe" explanation of our current understanding of what a particle is in a non-mathematical way.

Original Submission

 
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  • (Score: 5, Interesting) by c0lo on Wednesday November 18 2020, @02:05PM (11 children)

    by c0lo (156) Subscriber Badge on Wednesday November 18 2020, @02:05PM (#1078772) Journal

    Interesting FA, indeed.

    But... a good explanation for "average Joe"? I doubt it. Here's the list of explanations in TFA for what a particle is:

    1. A Particle Is a ‘Collapsed Wave Function’

      Quantum mechanics revealed to its discoverers in the 1920s that photons and other quantum objects are best described not as particles or waves but by abstract “wave functions” — evolving mathematical functions that indicate a particle’s probability of having various properties.

    2. A Particle Is a ‘Quantum Excitation of a Field’

      According to quantum field theory, particles are excitations of quantum fields that fill all of space.

      In positing the existence of these more fundamental fields, quantum field theory stripped particles of status, characterizing them as mere bits of energy that set fields sloshing. Yet despite the ontological baggage of omnipresent fields...,

    3. A Particle Is an ‘Irreducible Representation of a Group’

      It’s the standard deep answer of people in the know: Particles are “representations” of “symmetry groups,” which are sets of transformations that can be done to objects.

      Take, for example, an equilateral triangle. Rotating it by 120 or 240 degrees, or reflecting it across the line from each corner to the midpoint of the opposite side, or doing nothing, all leave the triangle looking the same as before. These six symmetries form a group. The group can be expressed as a set of mathematical matrices — arrays of numbers that, when multiplied by coordinates...

    4. ‘Particles Have So Many Layers’

      Just as particles are representations of the Poincaré group, theorists came to understand that their extra properties reflect additional ways they can be transformed. But instead of shifting objects in space-time, these new transformations are more abstract; they change particles’ “internal” states, for lack of a better word.

      Take the property known as color: In the 1960s, physicists ascertained that quarks, the elementary constituents of atomic nuclei, exist in a probabilistic combination of three possible states, which they nicknamed “red,” “green” and “blue.” These states have nothing to do with actual color or any other perceivable property.

    5. Particles ‘Might Be Vibrating Strings’

      Researchers placed even higher hopes in string theory: the idea that if you zoomed in enough on particles, you would see not points but one-dimensional vibrating strings. You would also see six extra spatial dimensions, which string theory says are curled up at every point in our familiar 4D space-time fabric.
      ... However, if any strings or extra dimensions exist, they’re too small to be detected experimentally. In their absence, other ideas have blossomed. Over the past decade, two approaches in particular have attracted the brightest minds in contemporary fundamental physics. Both approaches refresh the picture of particles yet again.

    6. A Particle Is a ‘Deformation of the Qubit Ocean’

      The first of these research efforts goes by the slogan “it-from-qubit,” which expresses the hypothesis that everything in the universe — all particles, as well as the space-time fabric those particles stud like blueberries in a muffin — arises out of quantum bits of information, or qubits. Qubits are probabilistic combinations of two states, labeled 0 and 1. (Qubits can be stored in physical systems just as bits can be stored in transistors, but you can think of them more abstractly, as information itself.) When there are multiple qubits, their possible states can get tangled up, so that each one’s state depends on the states of all the others. Through these contingencies, a small number of entangled qubits can encode a huge amount of information.

    7. ‘Particles Are What We Measure in Detectors’

      Strangely, calculations involving hundreds of pages of algebra often yield, in the end, a one-line formula. Amplitudeologists argue that the field picture is obscuring simpler mathematical patterns. Arkani-Hamed, a leader of the effort, called quantum fields “a convenient fiction.” “In physics very often we slip into a mistake of reifying a formalism,” he said. “We start slipping into the language of saying that it’s the quantum fields that are real, and particles are excitations. We talk about virtual particles, all this stuff — but it doesn’t go click, click, click in anyone’s detector.”...

      ...
      Arkani-Hamed and his collaborators, meanwhile, have found entirely new mathematical apparatuses that jump straight to the answer, such as the amplituhedron — a geometric object that encodes particle scattering amplitudes in its volume. Gone is the picture of particles colliding in space-time and setting off chain reactions of cause and effect. “We’re trying to find these objects out there in the Platonic world of ideas that give us [causal] properties automatically,” Arkani-Hamed said. “Then we can say, ‘Aha, now I can see why this picture can be interpreted as evolution.’”

    You got it, Average Joe? Come on, it's easy, you only need to know a bit of Algebra, Calculus, Statistical Mechanics, Topology, Information Theory, maybe a bit of Theory of Relativity to have a vague idea of what all above is about.

    --
    https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
    Starting Score:    1  point
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  • (Score: 2, Interesting) by Anonymous Coward on Wednesday November 18 2020, @02:25PM (5 children)

    by Anonymous Coward on Wednesday November 18 2020, @02:25PM (#1078780)

    Yeah, reading all that made me glad I decided not to go into physics as a career.

    I'm still not totally convinced that modern physics isn't just a scam that all the physicists are using to avoid having to dig ditches for a living. I mean, good on them if they are because it's clearly a damn good scam. I just can't tell them apart from the theologians at this point. (which is probably just because I personally can't understand a damn thing either group says)

    • (Score: 5, Funny) by c0lo on Wednesday November 18 2020, @02:44PM (2 children)

      by c0lo (156) Subscriber Badge on Wednesday November 18 2020, @02:44PM (#1078787) Journal

      I'm still not totally convinced that modern physics isn't just a scam that all the physicists are using to avoid having to dig ditches for a living.

      On the other side, I'm convinced that those who dig trenches for a living are just slackers who found a legal loophole to eschew learning modern physics (large grin)

      --
      https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford

      • (Score: 0) by Anonymous Coward on Wednesday November 18 2020, @06:47PM

        by Anonymous Coward on Wednesday November 18 2020, @06:47PM (#1078890)

        On the other side, I'm convinced that those who dig trenches for a living are just slackers who found a legal loophole to eschew learning modern physics (large grin)

        The laws of physics are different on the other side. For example, there are no door knobs on the other side.

      • (Score: 0) by Anonymous Coward on Wednesday November 18 2020, @07:26PM

        by Anonymous Coward on Wednesday November 18 2020, @07:26PM (#1078909)

        very brave: they totally and fully immersed are for real digging the field ^_^

    • (Score: 0) by Anonymous Coward on Wednesday November 18 2020, @05:04PM

      by Anonymous Coward on Wednesday November 18 2020, @05:04PM (#1078847)

      I feel the same way about patents and patent lawyers. Try reading through a bunch of patents and it all looks like nothing but confusing gibberish.

    • (Score: 2) by mhajicek on Wednesday November 18 2020, @06:33PM

      by mhajicek (51) on Wednesday November 18 2020, @06:33PM (#1078881)

      A particle is what collects on my cpu cooler.

      --
      The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek

  • (Score: 0) by Anonymous Coward on Wednesday November 18 2020, @04:02PM (3 children)

    by Anonymous Coward on Wednesday November 18 2020, @04:02PM (#1078822)

    The three main things to kinda look up when it comes to quantum physics that are unintuitive are

    Quantum Coherence / decoherence
    Quantum tunneling
    Quantum Non-locality

    You can find youtube videos on these.

    • (Score: 0) by Anonymous Coward on Wednesday November 18 2020, @05:00PM (2 children)

      by Anonymous Coward on Wednesday November 18 2020, @05:00PM (#1078845)

      Also these three concepts are related to object permanence and how you lose your natural intuition of quantum physics after a certain age when you gain object permanence.

      • (Score: 0) by Anonymous Coward on Thursday November 19 2020, @05:13AM (1 child)

        by Anonymous Coward on Thursday November 19 2020, @05:13AM (#1079089)

        Oh, you tease! You can't come out with such a delightfully nutty comment without going the full rant. I invite you to please expound further on your ideas.

  • (Score: 3, Informative) by Common Joe on Friday November 20 2020, @10:21AM

    by Common Joe (33) <{common.joe.0101} {at} {gmail.com}> on Friday November 20 2020, @10:21AM (#1079675) Journal

    You got it, Average Joe? Come on, it's easy, you only need to know a bit of Algebra, Calculus, Statistical Mechanics, Topology, Information Theory, maybe a bit of Theory of Relativity to have a vague idea of what all above is about.

    Ok, you got me. That was my opinion.

    I still think it's a much better read than most articles which require a PhD in physics with a specialization in string theory to understand. It won't satisfy the average Joe. It won't satisfy the physicist. But it at least satisfied this Common Joe, and I thought others on here would also appreciate it.