• Wayfarer
    6.9k
    Recent discoveries suggest that there's a perfect symmetry between matter and antimatter - meaning it's not clear why they didn't annihilate each other upon the birth of the universe. CERN's latest study sought to find out whether different magnetic properties accounted for matter's seeming victory after the Big Bang, but found another point of symmetry. Essentially, going by our findings so far, there simply shouldn't be a universe.

    More reports here

    So much for 'symmetry breaking' :-}
  • Michael
    7.6k
    Such a sensational headline. It should read "CERN discovers that current scientific models are missing something (or wrong somewhere)".
  • fdrake
    1.8k
    Or alternatively 'no reason to assume the universe is anything but a contingent accident'.
  • unenlightened
    3.1k
    I always said that morals were objective. Evidence of what ought not be at last! And it's universal.
  • apokrisis
    4.5k
    So much for 'symmetry breaking' :-}Wayfarer

    What are you rolling your eyes at? Do you think the symmetry ain't actually broke or something?

    The very fact that Cern can conjure up anti-matter to test is a demonstration that the symmetry breaking exists. And when matter and anti-matter annihilate back into a shower or radiation, that demonstrates also that the symmetry exists.

    It is just that proton and anti-protons are identical in their magnetic moment, just as they are with their charge and mass. So the source of the symmetry-breaking ain't that.
  • apokrisis
    4.5k
    Or alternatively 'no reason to assume the universe is anything but a contingent accident'.fdrake

    But an essential handedness has been found in the weak force. And the explanation is mathematical - chiral symmetry and its breaking by the Higgs mechanism.

    But not "enough" symmetry-breaking has been found in that one mechanism. So it would be useful to find a similar contribution from the strong force.

    Anyway, the working presumption is that the necessary symmetry-breaking asymmetry is not accidental but an exact mathematical feature that always "lurked" in the Big Bang's particle making. Things couldn't have been different.

    You've got to hand it to nature. Who would have thought that the mathematics of existence would have to embed the twist that meant all the positive mass particles were clunky great big triplet entities - protons - and all the negative ones were little point-like electrons?

    This baked-in symmetry difference built in a physical asymmetry which - once the Big Bang had expanded and cooled enough for it to be stably expressed - guaranteed things could evolve to be more complex.

    And indeed, life itself depends fundamentally on the fact of this size-difference in the charged particles. Life could happen as protons are too fat to squeeze through membranes. Life could develop as there was a size asymmetry it could exploit to control the flow of charge and thus extract work from that controlled flow.

    So everything about existence comes back to symmetries and their breaking. The Universe as we know it was mathematically pre-ordained.
  • fdrake
    1.8k


    Supporting links?
  • apokrisis
    4.5k
    To what in particular? I traversed a heck of a lot of ground there. If your reply is well-intentioned - you are actually curious - then sure I can dig out the supporting books or papers.
  • fdrake
    1.8k


    What informed you about: amount of symmetry breaking is insufficient and lurked in the big bang, chiral symmetry breaking in the weak force through the Higgs mechanism.

    Stuff about life (this life, whatever it is) depending on particle sizes, imagined you had proton channels and more fundamentally bonding in mind, don't think it needs more detail.

    As payment, check your PM inbox for a link.
  • apokrisis
    4.5k
    There is a vast literature on this. I could go digging for the best lay summary I guess.

    Here is a reliable source that is specific to the proton magnetic moment issue - https://profmattstrassler.com/articles-and-posts/particle-physics-basics/c-p-t-and-their-combinations/

    Very surprisingly, CP is not significantly violated by the strong nuclear force, and no one knows why. We know the strong nuclear force does not violate CP symmetry very much because of a certain property of the neutron, called an “electric dipole moment”.

    Now, how big would you expect the dipole moment of a neutron to be? Well, the neutron has a radius of about 10-13 cm, so you’d expect D should be about that size. And it consists of quarks, anti-quarks and gluons; the gluons are electrically neutral, but the quarks and anti-quarks have electric charges: 2/3 e (up quarks), -1/3 e (down quarks), -2/3 e (up anti-quarks) and +1/3 e (down anti-quarks). So you might expect q to be about that size. So you’d expect the neutron to have an electric dipole moment with a size in the vicinity of 10-13 e cm. That’s about a million times smaller than the dipole moment of a water molecule, mainly since the radius of a neutron is a million times smaller.

    Actually there are some subtle effects which make a more accurate estimate a little smaller. The real expectation is about 10-15 e cm.

    But if the neutron had an electric dipole moment, this would violate T, and therefore CP, if CPT is even an approximate symmetry. (It also violates P.) So if CP and CPT were exact symmetries, then the electric dipole of the neutron would have to be exactly zero.

    Of course we already know that CP is not an exact symmetry; it’s violated by the weak nuclear force. But the weak force is so weak (at least as far as it affects neutrons, anyway) that it can only give the neutron an electric dipole moment of about 10-32 e cm. That’s far smaller than anyone can measure! So it might as well, for current purposes, be zero.

    But if the strong nuclear force, which holds the neutron together, violates CP, then we’d expect to see an electric dipole moment of 10-15 e cm or so. Yet experiment shows that the neutron’s electric dipole moment is less than 3 × 10-26 e cm!! That’s over ten thousand million times smaller than expected. And so the strong nuclear force does not violate CP as much as naively anticipated.

    Why is it so much smaller than expected? No one knows, though there have been various speculations. This puzzle is called the strong CP problem, and it is one of the three greatest problems plaguing the general realm of particle physics, the others being the hierarchy problem and the cosmological constant problem.
  • fdrake
    1.8k


    Aight, I read the link, were you using it to say symmetry breaking is still a thing, contra the OP?
  • Wayfarer
    6.9k
    This puzzle is called the strong CP problem, and it is one of the three greatest problems plaguing the general realm of particle physics, the others being the hierarchy problem and the cosmological constant problem

    Just by way of footnote to the above, abstracts of the other two 'greatest problems'

    In theoretical physics, the hierarchy problem is the large discrepancy between aspects of the weak force and gravity. There is no scientific consensus on why, for example, the weak force is 1024 times as strong as gravity.

    In cosmology, the cosmological constant problem or vacuum catastrophe is the disagreement between measured values of the vacuum energy density (the small value of the cosmological constant) and the zero-point energy suggested by quantum field theory.

    Depending on the assumptions, the discrepancy ranges from 40 to more than 100 orders of magnitude, a state of affairs described by Hobson et al. (2006) as "the worst theoretical prediction in the history of physics."
  • apokrisis
    4.5k
    I don't understand your concern. You'll have to explain.

    Anti-matter exists. We can create it. But matter dominates the visible Universe. We can measure that.

    So there is an asymmetry - a symmetry-breaking - which is a foundational issue for cosmology and particle physics.

    And also an actual symmetry-breaking mechanism has been found for the weak force. Nobels have been awarded.

    The link talked about how the search was going in regards to the strong force.

    So I'm not seeing what you think might be the problem.
  • Wayfarer
    6.9k
    But matter dominates the visible Universe. We can measure that.apokrisis

    Well, not really - there's still the outstanding problem of dark matter.
  • apokrisis
    4.5k
    Just by way of footnote to the above, abstracts of the other two 'greatest problems'Wayfarer

    Science is a work in progress. Shock horror.
  • apokrisis
    4.5k
    Well, not really - there's still the outstanding problem of dark matter.Wayfarer

    Dark or bright, we know it is matter. If it were anti-matter, it would be blowing you to shit right now.
  • fdrake
    1.8k


    I don't have a problem. Was only asking for clarification.
  • noAxioms
    677
    Essentially, going by our findings so far, there simply shouldn't be a universe.
    Wrong conclusion. It finds that current models don't necessarily match what is seen. If the findings were accurate, the universe should be different, but concluding that it should not exist is an absurd category error.

    The universe didn't even start out with matter/antimatter that mutually annihilated. That stuff formed later. Yes, the imbalance has been noted and any model needs to account for that. Apparently not all models do.
  • Marchesk
    2.4k
    Confirmed universe is click baiting physicists.
  • Wayfarer
    6.9k
    Science is a work in progress. Shock horror.apokrisis

    That is not the point. It ought to give pause to any form of physicalism that such questions are still so wide open.

    Confirmed universe is click baiting physicists.Marchesk

    This comment would definitely win the Lucky Door Prize, should there have been one. :-)
  • apokrisis
    4.5k
    It ought to give pause to any form of physicalism that such questions are still so wide open.Wayfarer

    It should give far more pause to the peddlers of metaphysical stories that "can't even be wrong".

    What you are saying is science knows that the Big Bang is a story of symmetry and symmetry-breaking. It even has mathematical theories backed up by experimental confirmation of just how much symmetry-breaking is being delivered by particular physical mechanisms. And so now, the job is finding the machinery to explain the amount of symmetry-breaking that is known to be missing.

    You do realise that you only hear about these "crises in physics" because physics is right on the doorstep of an answer?

    It has a range of candidate theories - any number of them generated by its armies of theoreticians. It has quantified the amount of "missing information" it might looking for. It is searching for what it knows has to be there - some known unknowns. And all it needs is a few billion of your tax-payer dollars to take the next step.

    The cosmological constant problem and the hierarchy problem are just the same. Physics is advertising the work it could get going with if you give it the grants.

    It may indeed be the case that the physics community will prove that on these ones "it just doesn't have a clue".

    But when it comes to antimatter, Dirac already predicted positrons, or anti-matter electrons, had to be the case back in 1928. That just fell out of the maths of relativistic quantum physics.

    Then once the Big Bang became a thing, everyone immediately knew that there had to be some mechanism for favouring particles over their anti-particles for particles to even exist. It is was as obvious as stumbling into a city in a forest and asking, well who built this?

    Sakharov defined the three symmetries which would have to be broken to fit the facts - particle number, charge and/or parity, and the thermodynamic arrow of time.

    So you must end up with more than one than the other (otherwise any pair would mutually annihilate). And then time symmetry must be broken, otherwise the Universe could grow hotter again and just melt any matter particles.

    So the critical part of the machinery must be charge/parity. The finger pointed at the maths of intrinsic spin. Something about that had to be the key - the explanation for why a hot swamp of Big Bang radiation would produce slightly more of one kind of matter than the other.

    And so since the 1960s, science has chewed is way through a lot of theories, a lot of experiments. The level of understanding has become spectacular.

    But to keep climbing towards the critical energy range is an exponential effort. Testing weak force level theories is easy-peasy compared to achieving the collider energies to test strong force level theories.

    So stop being so cheapskate and vote Cern the trillions it needs to get on with the job. ;)
  • Wayfarer
    6.9k
    You do realise that you only hear about these "crises in physics" because physics is right on the doorstep of an answer?apokrisis

    'Realise'? I don't see any need to accept that; science may never solve these issues. I'm pretty certain that they won't in my lifetime; the gaps are getting bigger, not smaller. The confident predictions of science providing a naturalistic 'theory of everything' seem to be getting more, not less, remote. I mean, good luck, and all (as if the kvetching of an arts graduate on a philosophy forum amounts to anything) - but an accelerator the size of the orbit of the Moon could be built, and yield only a series of proportionately larger mysteries. (Interesting article on that very point by Stephen Weinberg, The Crisis of Big Science. )

    As far scientific cosmology is concerned, I am aware that at least some respectable scientists entertain the idea that 'The Big Bang' might have been one of a series. I don't see any logical reason why, if it happened once, it can't happen repeatedly. In which case, we're back at the Myth of the Eternal Return and a cyclical cosmos which, for unknown reasons, seems to have formed the backdrop of ancient Indian cosmology. ('Breathe in, breathe out. Breathe in, breathe out.....')
  • apokrisis
    4.5k
    The confident predictions of science providing a naturalistic 'theory of everything' seem to be getting more, not less, remote.Wayfarer

    That confident assertion would be more believable if it were backed up by some reasons to show science has been failing to make continual progress.

    Only about a century ago, atoms were still half-regarded as a fiction. Now we can blow up the planet with nuclear bombs. :)

    As far scientific cosmology is concerned, I am aware that at least some respectable scientists entertain the idea that 'The Big Bang' might have been one of a series.Wayfarer

    Only half a century ago, no-one had reason to be certain that the Cosmos was even created once by a Big Bang.

    In which case, we're back at the Myth of the Eternal Return and a cyclical cosmos which, for unknown reasons, seems to have formed the backdrop of ancient Indian cosmology.Wayfarer

    And so you just reveal how you are happy with any old theory - just so long as it chimes with your own metaphysical preferences.

    The same with panspermia and any other half-baked speculation that gets a good run in the popular press.
  • Wayfarer
    6.9k
    you just reveal how you are happy with any old theoryapokrisis

    Hey they all beat being 'a dissipative structure', if you ask me ;-)
  • Metaphysician Undercover
    5.2k
    You do realise that you only hear about these "crises in physics" because physics is right on the doorstep of an answer?

    It has a range of candidate theories - any number of them generated by its armies of theoreticians.
    apokrisis

    Two contradictory statements one after the other. Physics is on the doorstep of the answer. It has a whole range of possible answers.

    Of course, the reality is that they're nowhere near an answer, or else they wouldn't have armies of theoreticians going in completely different directions. This evidence, of armies of theoreticians going in completely different directions, indicates that actually they are completely lost.
  • apokrisis
    4.5k
    You’ll have to try harder than that if you’re wanting to troll me MU.
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