[HN Gopher] Mysteries the Standard Model can't explain
___________________________________________________________________
Mysteries the Standard Model can't explain
Author : jc_811
Score : 169 points
Date : 2021-11-18 10:51 UTC (12 hours ago)
(HTM) web link (www.symmetrymagazine.org)
(TXT) w3m dump (www.symmetrymagazine.org)
| bmitc wrote:
| The standard model and particle physics has become basically a
| religion for some scientists.
|
| > "As for the question 'What are we?' the Standard Model has the
| answer," says Saul Ramos, a researcher at the National Autonomous
| University of Mexico (UNAM). "It tells us that every object in
| the universe is not independent, and that every particle is there
| for a reason."
|
| Because this makes no sense unless you're operating under some
| sort of belief system.
| not2b wrote:
| Except that all those physicists will tell you that they know
| that the Standard Model is incomplete, and therefore it is in
| some sense wrong. Religious people won't tell you that about
| their holy books.
| blackhaz wrote:
| Can wave-particle duality be considered as part of the riddle?
| littlestymaar wrote:
| The wave/particle duality is just an illusion, a feature of how
| we model physical objects, and ultimately how we teach physics.
|
| Neither waves or particles exist in the real world, but we do
| _model_ some features of the world through them. Particles and
| waves are just the solutions to the differential equations
| found in classical mechanics, and electromagnetism (which,
| interestingly enough, rely on the same mathematical framework).
| Then when teaching about them, we use analogies from the
| perceptible world. (And those analogies are wrong btw, waves in
| the sea don 't really behave like physics "waves").
|
| In quantum mechanics, the equations are completely different
| ones, based on a completely different branch of mathematics.
| Then unsurprisingly their solutions have little in common with
| those above.
| f154hfds wrote:
| I have a particle physicist friend I asked this very question
| to last year. He laughed and told me that this is not something
| that keeps physicists up at night. After doing a fair bit of my
| own research and watching a lot of PBS Spacetime it does make
| more sense to me. Someone with more knowledge please check my
| understanding: Quantum Field Theory treats everything as a wave
| and 'particles' arise as a result of a 'collapse' of that more
| fundamental wave (probability distribution) as we decide to
| probe our uncertainty budget by getting specificity on the
| locality of the particle. It can also collapse of course by
| interacting with a combinatorial explosion of other particles
| (such as the back wall of the double slit experiment).
|
| If the above is accurate I still think the collapse is a
| strange phenomenon that we shouldn't just take on faith
| (without probing deeper of course) - the disagreement between
| Copenhagen and Many Worlds (and the lack of a testable
| hypothesis) seems to indicate the collapse itself isn't well
| understood [1]. Many Worlds seems to have an elegant solution
| but it needs experiment and wasn't (and probably still isn't)
| 'accepted' by the overall community.
|
| [1]
| https://en.wikipedia.org/wiki/Wave_function_collapse#History...
| FeepingCreature wrote:
| There is no experiment that can settle this - collapse can be
| shown to exist, but it cannot be shown to not exist, just not
| for a particular system at a particular scale. In other
| words, experimenters can push the possible size of a quantum
| superposition upwards, but they will never be able to
| disprove the claim "if it were but a bit bigger, it would
| collapse."
| criddell wrote:
| If I have some system in a quantum superposition state and
| I simultaneously measure it in n different ways, will all n
| measurements produce the same result?
| rocqua wrote:
| I remember a Physics PhD who thought that 'waveform
| collapse' was not a transition from 'waveform' to
| measurement. Instead, he felt that 'measurement' was just
| becoming entangled with the wider world, which causes the
| waveform to converge to a dirac-delta distribution.
|
| Are there reasons to assume that 'random' entanglements
| cause the waveform to 'concentrate'? it would need to be
| that the probability of concentration at a given 'point' is
| proportional to the square magnitude of the waveform? Has
| this been studied?
| ajkjk wrote:
| That is the correct model of what wavefunction collapse
| is. And yes, there are huge amounts of research in how
| the effects of random entanglements --
| https://en.wikipedia.org/wiki/Quantum_decoherence is the
| general concept.
| mikhailfranco wrote:
| No, it's quite clear in QFT that elementary entities:
|
| - travel as unitary time-reversible non-local waves (propagate,
| interfere, entangle)
|
| - interact as non-unitary time-irreversible local particle
| events (position, time, exchange, create, destroy)
|
| Your interpretation of quantum mechanics will determine how you
| imagine the two views connect (Born Law, Many Worlds, ...)
| ajkjk wrote:
| I don't think it's correct to say that they interact as
| particle events, because off-shell interactions are a thing,
| and interacting strictly as particles would prohibit that,
| no?
| mabbo wrote:
| Many years ago, a friend (who is far smarter than I am) said
| something to me that made wave-particle duality click:
|
| "It's not that it's sometimes a particle and sometimes a wave.
| It's that very small things have a bunch of properties: some
| are shared with waves, and some are shared with small solid
| objects."
|
| We're duck-typing what we see and going "aha! It's a particle!
| No wait, now it's a wave!" but the class simply has both sets
| of methods on it and does not care how we classify it.
| Angostura wrote:
| That doesn't really help me understand how a single 'thing'
| interferes with itself when travelling through a double slit,
| unfortunately.
| goohle wrote:
| See it there: https://www.youtube.com/watch?v=nsaUX48t0w8
| [deleted]
| mabbo wrote:
| Because that's a thing it can do. It's properties include
| self-interference.
|
| You are building your expectations of 'what a thing can do'
| based on the macro world you live in and the things you see
| and experience 'up here'. But down there, the rules are
| simply different.
|
| Our expectations and intuition are simply not evolved to
| handle situations that occur in that level of reality.
| We've never thrown a rock and watched it self-interfere.
| But we should throw a lot of doubt at anyone who claims
| that it's all very natural to them, imho.
| goatlover wrote:
| Sure, but there are still different interpretation of QM
| to sort out, and electron jumps have recently been
| measured to take time. Which contradicts the idea that
| jumps were instantaneous. We don't know everything about
| QM, so it's right to push back somewhat on claims that
| it's just different. Isn't that basically saying shut up
| and calculate?
| criddell wrote:
| I've always wondered if the particle is traveling at the
| speed of light, is there any sense of sequence in that
| frame? Interference would require it to be at point A
| before point B. If I understand it correctly, for the
| particle no time passes between when it is emitted on the
| front side and detected on the back side.
|
| So could that interference just be what the path of least
| resistance looks like in a different frame?
| __s wrote:
| If you view a body of water as a single thing, would you
| think it odd that its wave interferes with itself in the
| double slit? The issue isn't unintuitive phenomena
| _(intuitive being patterns in microscopic /macroscopic
| scale which match by analogy to patterns you've learnt all
| your life from phenomena at your scale)_, but inadequately
| modeled phenomena
|
| https://youtu.be/citY6G8ePJw?t=223
|
| > But what can I call it? I can say they behave like a
| particle-wave or they behave in a typical quantum
| mechanical manner. There isn't any word for it, if I say
| they behave like particles, I give the wrong impression if
| I say they behave like waves. They behave in their own
| inimitable way. Which, technically, could be called the
| quantum mechanical way. They behave in a way that is
| nothing like anything you have seen before. Your experience
| with things you have seen before is inadequate, is
| incomplete. The behavior of things on a very tiny scale is
| simply different ... Well, there's at least one
| simplification, at least electrons behave exactly in this
| respect as photons, that is they're both screwy, but in
| exactly the same way ... But the difficulty really is
| psychological, and exists in the perpetual torment that
| exists from your saying to yourself "But how can it be like
| that?" which really is a reflection of an uncontrolled by
| say an utterly vain desire to see it in terms of some
| analogy with something familiar. I will not describe it in
| terms of an analogy with something familiar. I'll simply
| describe it
| mabbo wrote:
| Before opening the link, I read the text and thought
| "This sounds like Feynman!"
|
| The man truly had a way of speaking that is instantly
| recognizable.
| danielheath wrote:
| I always struggled with that too - I found this Veritasium
| video helpful
|
| https://www.youtube.com/watch?v=WIyTZDHuarQ&ab_channel=Veri
| t...
| __s wrote:
| Never heard of this, looked up whether there was some gap
| in the theory the video failed to mention, found a
| discussion on why this model isn't more pervasive:
| https://physics.stackexchange.com/questions/341400/why-
| would...
|
| & one comment which specifically separates pilot waves
| from the bouncing droplet demo https://old.reddit.com/r/q
| uantum/comments/7crdz6/whats_wrong...
| casparvitch wrote:
| No, physicists are pretty comfortable with that one. It isn't
| immediately intuitive, but the models we have are powerful and
| predictive. There is of course a somewhat open question as to
| the _interpretation_ of quantum mechanics. That question is
| almost metaphysics, whereas the problems quoted in the article
| are more holes in our present theory.
| hdjjhhvvhga wrote:
| Well, they're comfortable because the phenomenon is well-
| studied, we have very good models and can with good accuracy
| predict what will happen. What we don't know is why exactly
| it behaves in this way.
| andrewgleave wrote:
| One explanation is the "Many-Worlds" interpretation of
| quantum mechanics: https://en.wikipedia.org/wiki/Many-
| worlds_interpretation
| khafra wrote:
| The word "why" (and other references to causation) don't
| work in a normal way when you're talking about fundamental
| physics, because fundamental physics is the lowest-level
| model within which causation takes place.
|
| To ask "why" some part of the standard model is the way it
| is, you either invoke some rubric for comparing models,
| like Occam's Razor; or you indulge in metaphysics and
| speculate on the nature of whomever is running the
| Simulation. Either of these is a different meaning than the
| "why" of "why do rockets work in space."
| hdjjhhvvhga wrote:
| Well, you made quiet a few assumptions here. We don't yet
| know how much fundamental quarks are and what (if
| anything) hides in the subquark level.
|
| Given the lack of adequate instruments, our minds and
| unconventional approaches are our most powerful tools at
| this point. For example, we generally consider the space
| between particles as void. We can't see anything, we
| can't detect anything, so we assume there's nothing
| there. But for what it's worth, there could be trillions
| of unknown particles that don't interact with matter. So
| why would it matter, you ask? Because it's not impossible
| that under certain conditions some of these might cluster
| into matter or interact with it in unobvious ways. The
| existence of dark matter and energy (or the related
| phenomena) indicates this is not impossible.
|
| But yes, I see your point. However, I hope we get deeper
| into understanding this phenomenon before I die. Who
| knows, maybe it's because of some yet-undiscovered aspect
| of photons, and metaphysical speculation is not
| necessary?
| DangitBobby wrote:
| I thought the most surprising thing about wave/particle
| duality is that the act of observation itself is what causes
| the waveform of particles to collapse. Do we know of a
| mechanism for that? Are we not still surprised that you
| change the outcome of events by changing where you look?
| ajkjk wrote:
| No one (today) really believes that it is the observation
| that 'causes' a change in the experiment. What is happening
| is that the observer is becoming entangled with the
| experiment.
| FeepingCreature wrote:
| As I understand it, collapse is an artifact of the
| necessity to derive classical results from an experiment.
| You can think of it as "at a certain scale, calculating
| this as a quantum system as opposed to classical is no
| longer worth it." But it's of course still a quantum
| system, because everything is quantum all the time.
| jonquark wrote:
| Not really in the same way.
|
| The Standard Model is built out of quantum field theories that
| take as a given our experiment results that matter on quantum
| scales is unlike the "large scale" matter we see around us.
|
| The problems described in the articles are unexpected results
| that we see in our experiments compared to the Standard Model,
| "weird/nonintuitive" aspects of modern particle physics would
| be a separate article.
| immmmmm wrote:
| no the SM is a quantum field theory: particles are excitations
| of quantum fields, so wave-particle duality is implicit. these
| fields, at the classical level are function that take a space
| time coordinate as an argument (space time filling) and
| typically yields a vector in some vector space (except the
| higgs field which is a scalar). this vector space in turn is a
| representation of some symmetry group. the symmetry group of SM
| is U(1)xSU(2)xSU(3).
| morelandjs wrote:
| I'd add to this, that we know very little about the spatial
| distribution of nuclear matter at and below the scale of a
| nucleus. The standard model excels at understanding the salient
| characteristics of asymptotic states before and after an
| interaction, things like spin, lepton number, etc. But we still
| can't tell you how gluons are distributed inside the proton.
| evanb wrote:
| We're not all the way there yet, but this is a hot and rapidly-
| advancing topic. See, eg. https://arxiv.org/abs/2111.06948 and
| sources therein.
| indutny wrote:
| Nor can we tell why proton is a spin 1/2 particle because the
| gluon soup and particle-antiparticle pairs make this
| complicated.
| dwheeler wrote:
| I would add, why do certain particles decay into other particles?
| For example, the tau particle contains nothing else, as far as we
| can tell, yet it decays into certain other particles (and not the
| same ones every time).
|
| More generally, the standard model records a lot of particles and
| things that happen, but not why those instead of others. I
| suspect there's a simple model underneath, but I have no idea
| what it is.
| tsimionescu wrote:
| Coincidentally, Sabine Hossenfelder (a theoretical physicist)
| had just had a piece on this topic:
|
| http://backreaction.blogspot.com/2021/11/why-can-elementary-...
| evanb wrote:
| As a physicist I'd say these things are well understood.
|
| - Why do certain particles decay into other particles?
|
| Quantum mechanics is totalitarian: what ever is not forbidden
| is mandatory. Forbidden: excluded by some symmetry principle
| (violation of a conserved quantity, like energy, angular
| momentum, ...)
|
| - The tau decays into certain other particles (and not the same
| ones every time).
|
| Tau carries electric charge, fermion number, angular momentum.
| The decay products' total quantum numbers match that of the
| tau. But the quantum-mechanical totalitarian principle says
| that _every_ possible combination that satisfies that
| constraint happens with some amplitude.
|
| - The standard model records a lot of particles and things that
| happen, but not why those instead of others. I suspect there's
| a simple model underneath, but I have no idea what it is.
|
| If by 'those' and 'others' you mean all the varied observed
| phenomena, then yes, there is a simple model underneath and it
| IS the standard model. If by 'those' and 'others' you mean 'why
| is the SM the way it is', that's (likely) an out-of-bounds
| question for the SM in the first place. But a modern
| perspective on the SM is to think of it as a low-energy
| effective field theory anyway.
| umvi wrote:
| Is there any evidence of "dark matter" or "dark energy" actually
| existing?
|
| I find it more likely that we just don't understand the real
| mechanisms behind galaxy rotation and universe expansion and so
| we just made up unfalsifiable stopgaps to make the numbers work
| out.
| ajkjk wrote:
| There is vast amounts of evidence for dark matter existing.
|
| Dark energy is an unrelated concept with a similar name, and
| there is not really evidence for it; it is speculated because
| the equations of general relativity imply the need for an
| additional term to justify the inflation of the universe, but
| it's not at all clear what this term corresponds to in terms of
| matter.
| nimish wrote:
| No there isn't. There's a bunch of evidence that the current
| model used for cosmological dynamics (Friedmann's equations)
| don't work unless there's a lot of undetected stuff called
| dark matter.
|
| Until someone rules out stuff like using the full nonlinear
| Einstein equations vs Friedmann equations, or that the
| presumption of homogeneity/isotropy is wrong, (there's more
| stuff here that hasn't quite been excluded by observation)
| then the best we can say is that "We need some extra matter
| called dark matter for the standard cosmological model to
| work"
| dahfizz wrote:
| Dark matter is especially dubious to me. Is it possible its
| literally matter which is dark? i.e. there are more planets and
| asteroids and mass than we can see because it is not
| illuminated? How can we be confident in our prediction of the
| mass of distant galaxies?
|
| Maybe that is what is meant when a physicist says dark matter,
| and its the media that mysticizes it.
| AnIdiotOnTheNet wrote:
| As mentioned elsewhere, I'm an idiot not a physicist, but as I
| understand it dark matter is favored over modified gravity
| theories because all such theories are considered to be lacking
| in parsimony. Essentially, instead of showing how the behavior
| we observe arises from a fundamental simplicity, they are
| adding and tuning parameters to fit. With enough parameters one
| can fit any arbitrary shape, but this doesn't give the model
| any predictive power.
|
| I also get the impression that while dark matter is popularly
| accepted as "actually existing", that is much less the case for
| dark energy.
| JudasGoat wrote:
| I always find it curious that both dark matter and dark energy
| aren't available locally to study.
| AnimalMuppet wrote:
| They might be, but only in very small quantities. The amount
| of dark matter that we would need to "fix" the galaxy
| rotation problem... would it affect the orbits of things in
| the solar system at all? (OK, yes, it would, but
| _observably_?) I haven 't done the math, but I strongly
| suspect that the answer is "no".
| AnIdiotOnTheNet wrote:
| It likely is, we just can't detect it on such small scales.
| It would be a form of matter that interacts pretty much only
| via gravity, and since gravity is already 40 orders of
| magnitude weaker than the electromagnetic force we usually
| use to detect things, it's understandable that it is kinda
| hard to see.
| azalemeth wrote:
| One other mystery not mentioned is the problem of fine tuning.
| The standard model requires certain parameters (like alpha, the
| fine structure constant) to have their current values accurate to
| many orders of magnitude for the universe as we know it to exist.
| There are two philosophical schools of thought about that -- (a)
| we're in the universe we're in, so by definition it must exist
| and there's a selection bias there; or (b) there is an underlying
| detailed structure that gives the values of supposed
| 'fundamental' quantities their shape as an emergent property of
| something more beautiful - and thus they're not "free" at all.
| This is one of the things that SUSY was supposed to solve - but
| it's been experimentally found to not really exist by the LHC. A
| good introduction about this (in the context of the Higgs mass,
| where the need for fine tuning is really apparent) is here:
| https://www.physicsmatt.com/blog/2016/11/17/paper-explainer-...
| pfortuny wrote:
| Thanks for this detailed explanation. Did not know about the
| fine-tuning problem.
| jessermeyer wrote:
| It's only framed as a problem when it is assumed that the
| values could be other than what they are. But we have no
| reason to suspect that they could be different. We have no
| idea how unlikely the current selection is given our
| observation is a single observable. For all we know, it's
| certain.
|
| 'What really interests me is whether God had any choice in
| creation' - Albert Einstein
| brink wrote:
| > It's only framed as a problem when it is assumed that the
| values could be other than what they are.
|
| Well then your problem would be "What fixed those values to
| what they are?", which I don't think is the lesser of a
| problem.
| andrewgleave wrote:
| You may find this an interesting read:
|
| https://www.bretthall.org/fine-structure.html
| pfortuny wrote:
| Well, thanks again!
| rrdharan wrote:
| Also this free book on the Anthropic Principle is great:
| https://www.anthropic-
| principle.com/q=book/table_of_contents...
| Mizza wrote:
| "This is rather as if you imagine a puddle waking up one
| morning and thinking, 'This is an interesting world I find
| myself in -- an interesting hole I find myself in -- fits me
| rather neatly, doesn't it? In fact it fits me staggeringly
| well, must have been made to have me in it!' This is such a
| powerful idea that as the sun rises in the sky and the air
| heats up and as, gradually, the puddle gets smaller and
| smaller, frantically hanging on to the notion that everything's
| going to be alright, because this world was meant to have him
| in it, was built to have him in it; so the moment he disappears
| catches him rather by surprise. I think this may be something
| we need to be on the watch out for."
|
| --Douglas Adams
| crznp wrote:
| The puddle being in a hole implies a world outside of the
| hole. If the puddle has no means to perceive the outside
| world except a careful inspection of its own bounds, isn't
| that an interesting mystery?
| teorema wrote:
| See also Professor Pangloss.
| AnIdiotOnTheNet wrote:
| To me the fine tuning problem is a bit like saying "circles
| wouldn't exist without p being exactly the value it is" and
| wondering why p has that value specifically and not any other
| value.
|
| I don't think A and B are mutually exclusive. The values seem
| perfectly tuned for our universe because we exist in our
| universe, and they are probably emergent from a more
| fundamental parameter, possibly something like the particular
| Calabi-Yau manifold topology that happens to correspond to our
| universe (in the case of superstring theory). If we lived in a
| different CY topology that was capable of supporting
| intelligent life then we'd wonder why that one's constants are
| so precisely tuned for us.
|
| But then, I'm and idiot who just watches PBS Space Time and
| nods his head, not a physicist.
| dogma1138 wrote:
| That's not that great analogy for fine tuning. The quantized
| representative value of Pi is arbitrary based our numerical
| system, the relationship that derives it is fixed if the
| relationship would change circles indeed would not exist.
|
| Let's move the analogy to triangles a triangle has 180
| degrees but that only holds true when it's on a flat surface
| if you have a curvature it can have more or less than 180
| degrees.
|
| So this isn't a fine tuning problem on its own, if you would
| lived in a universe where triangles have less or more than
| 180 degrees it would represent a universe with negative or
| positive curvature.
|
| The issue with fine tuning is that the curvature of the
| universe is directly tied to the mass/energy density and any
| deviation from an extremely narrow range which our universe
| seems to sit in out of all possible values would not just
| produce a universe with triangles with fewer or more degrees
| than 180 but would either produce a universe that would
| collapse on itself within a blink of an eye or expand so fast
| that gravity would never be strong enough to cause even the
| most basic structures to form.
|
| So the issue really is that to produce a universe which will
| form galaxies and stars and survive long enough to produce
| life you need a lot of parameters at a certain very specific
| value even the smallest of deviations would not produce a
| universe that would ever support life, yet alone an
| intelligent life. What's even stranger iirc is that the
| values have to be really what they are now you can't simply
| 2X all of them to maintain the proportions and get the same
| result.
|
| And this is really what people are looking to solve, yes the
| androcentric is a solution if they were anything than what
| they are now we wouldn't be here to discuss why, but the
| issue is that out of all other possible combinations you
| don't seem to find another stable state and that is the true
| mystery.
| wruza wrote:
| _would either produce a universe that would collapse on
| itself within a blink of an eye or expand so fast that
| gravity would never be strong enough to cause even the most
| basic structures to form_
|
| It could do so in other chunks of space or time. If "time"
| and "expansion" have no final end, and these constants can
| fluctuate for some reason, eventually there would appear a
| universe like ours. There is no one who could count all the
| "failed" attempts. And maybe ours is also a failure in a
| sense, compared to a hypothetical much "better" universe.
| dogma1138 wrote:
| That is still fine tuning, in fact one of the more common
| interpretations of it just have an infinite number of
| universes one of them has to turn out to be alright...
| BlueTemplar wrote:
| Hmm, but isn't this very similar to taking the
| "multiverse" explanation and moving it into a "timeverse"
| ?
| hutrdvnj wrote:
| > other possible combinations you don't seem to find
| another stable state and that is the true mystery.
|
| Is that really the case, I thought in theory there could be
| a massive amount of other stable universes with different
| values. The number of unstable universes is of course much
| larger.
| dogma1138 wrote:
| That would be SUSY which solves issues like the hierarchy
| problems and other fine tuning constraints.
| occamrazor wrote:
| > androcentric
|
| I suppose you mean _anthropocentric_ (or the anthropic
| principle).
|
| The prefix andro- refers to men, in the sense of male
| (adult) humans; anthropo- instead to men in the sense of
| all humans.
| JackFr wrote:
| > yes the androcentric is a solution
|
| Anthropocentric I think you mean. Andro- would refer to the
| male sex rather than humankind -- which is I claim I doubt
| many physicists would make.
| dogma1138 wrote:
| Typing Antrocentric auto corrects to androcentric, you
| are correct off good thing this isn't Twitter or I would
| be forced to apologize by now.
| simiones wrote:
| > The issue with fine tuning is that the curvature of the
| universe is directly tied to the mass/energy density and
| any deviation from an extremely narrow range which our
| universe seems to sit in out of all possible values would
| not just produce a universe with triangles with fewer or
| more degrees than 180 but would either produce a universe
| that would collapse on itself within a blink of an eye or
| expand so fast that gravity would never be strong enough to
| cause even the most basic structures to form.
|
| Well, the notion of "extremely narrow range" is arbitrary.
| There is no mathematical notion of "large numbers" vs
| "small numbers". If the constants you speak about were
| 10^-g64 (Graham's number) times larger or smaller than they
| are, nothing would really change. If they were 2 times
| smaller, the universe would be extremely different.
|
| But 2 and 10^-g64 are just numbers. Neither of them is
| inherently large or small. We just happen to understand 1,
| 2, 3, ... much better than g64.
|
| You could say that there is a surprising amount of leg-room
| in the values of some constants of nature, while others can
| only vary in a reasonable range. While the fine-structure
| constant can vary within a reasonable +-1/1000 range
| without massive changes, other values can vary by massive
| numbers such as +-2!
| panda-giddiness wrote:
| I'm not sure I understand your point. There is such a
| thing as "large" and "small" in physics, but they're
| relative to the scale you're considering. For example, if
| you're a million miles from the Earth, then from a
| gravitational perspective you may as well be infinitely
| far away (a ~ 10^-5 g). But if you were the same distance
| from the sun, gravity would be extremely relevant for you
| (a ~ 5 g).
|
| Moreover, I find it unfathomable that the scale 1/g64
| would be relevant _anywhere_ in physics - I certainly can
| 't think of any examples!
| dogma1138 wrote:
| The range doesn't have anything to do with "numbers"
| directly because yes you can always say there is an
| infinity between any two numbers no matter how close they
| are to each other. The very limited range is actually
| captured in physical quantities.
|
| Back to the original analogy Pi is always exactly Pi not
| because we count it as 3.14~... but because of the
| relationship between the various innate properties of a
| circle.
|
| So fine tuning isn't that oh gosh we got very oddly
| specific values here is that we have problems such as
| https://en.m.wikipedia.org/wiki/Hierarchy_problem that
| are only solvable through fine tuning.
|
| So back to the circle it's really a case of use not
| understanding the relationship between the circumference
| and the radius and just brute forcing the value of Pi
| which is really what fine tuning is.
| tsimionescu wrote:
| Sure, but none of this must have a fundamental
| explanation. It could just be the way the universe is,
| nothing in maths requires this 'problem' to have a
| solution.
|
| Conversely, things like the measurement problem, quantum
| gravity, dark matter, dark energy, the mass of neutrinos
| and others must have some answer - they are facts we can
| see that just don't mesh with current theories.
|
| So why study a problem that there is no reason to believe
| will have an ultimate answer, when you can study problems
| that must have such an answer?
| dogma1138 wrote:
| Ok let me try to maybe make it simpler.
|
| Back to the circle... take a string and pin trace a
| circle with it, take another piece of string and trace
| it.
|
| Cut the traced string in half each half would not have
| the value Pi (granted the original string you had used to
| draw the circle has a value of one). That relationship is
| fundamental and the answer we are trying to find is
| exactly is this fundamental relationship that would
| explain why the constants have the values they have.
|
| As in there needs to be a certain mechanism that defined
| those values in relationship to each other in a manner
| that does not require "fine tuning" because that would
| require either an infinite number of other universes
| which can have different values regardless of the fate of
| those universes or a cycle of death and rebirth in which
| these values somehow can be randomized (which opens a
| whole other question how does that happen?).
| otabdeveloper4 wrote:
| > And this is really what people are looking to solve
|
| Why would you want to "solve" a basic fact of life?
|
| Smells of ideology.
| SAI_Peregrinus wrote:
| "explain" might be a better word than "solve" there.
| People are looking to solve the question "why are the
| fundamental constants of physics what they are?" which
| isn't a problem in the sense of something wrong but more
| something that needs an explanation for a full
| understanding to be possible.
| nicoffeine wrote:
| According to Leonard Susskind[1], fine tuning is a compelling
| argument by itself[2], and the strongest case is the
| cosmological constant.[3] In a nutshell it is a sort of
| repelling force first proposed by Einstein to create a
| workable model for a static universe who later regretted it
| as one of the biggest mistakes in his career. However, the
| theory is now back with Nobel prize winning research showing
| that expansion is accelerating, which would require a
| positive number. It could explain a large portion of "dark
| matter."
|
| When expressed in one way, it is 10^-122 "units of the square
| Planck length". I'm not smart enough to completely understand
| it, but it is (according to physicists) an incredibly precise
| ingredient in the various properties of physics that make our
| Universe possible. Any larger or smaller and the model falls
| apart. If it is an accident, that is one hell of a lottery
| ticket.
|
| [1] https://en.wikipedia.org/wiki/Leonard_Susskind
|
| [2] https://www.closertotruth.com/interviews/3081
|
| [3] https://en.wikipedia.org/wiki/Cosmological_constant
| josefx wrote:
| > and wondering why p has that value specifically and not any
| other value.
|
| Maybe the question should be "why circles" then. Early models
| of the solar system suffered under the assumption that
| everything should be modeled using circles when ellipses
| modeled everything better.
| Ginden wrote:
| > (a) we're in the universe we're in, so by definition it must
| exist and there's a selection bias there;
|
| This has basically 3 possible explanations - insane
| coincidence, multiverse (with many versions of constants;
| certain forms of mathematicism also provide such "multiverse")
| or "reason" (simulation admin/God).
| throwawaylinux wrote:
| Isn't the whole thing made up to fit observation though? Why is
| that any more arbitrary than, say, electromagnetism existing?
| TheOtherHobbes wrote:
| It's an explanatory theory with a lot - a _lot_ - of gaps.
|
| It has been extended with some nice predictions like the
| Higgs. But basically it's a Franken-patchwork of math glued
| together quite awkwardly.
|
| Because that is what it is. Literally. It was developed by
| thousands of grad students and their supervisors throwing
| math at the wall and keeping anything that matched
| observations. So there was a lot of random searching
| involved.
|
| What's missing is a central guiding _metaphor_.
|
| Relativity has one. In comparison, the Standard Model is very
| epicycle-ish tool for calculating Lagrangians with plenty of
| "Yes but" and "Except when".
| throwawaylinux wrote:
| I'm not sure I quite explained myself, although I do
| appreciate the reply.
|
| See, I also don't see how one central guiding metaphor
| would be any less arbitrary than none, or ten metaphors.
|
| What I am asking is why would a = 0.0072973525693 be more
| of a problem than electromagnetism or the speed of light
| being constant or e=mc^2? If the fine structure constant
| was exactly 1 would that make it better? Why is 1 less
| arbitrary or more good?
|
| I understand the beauty in simplicity, fewer concepts or
| ideas, smaller formulas explaining more things, 1 being
| "nicer" than other numbers, etc. So I understand that
| aspect of goodness, so it is the connection to underlying
| observable reality I'm asking about.
|
| Because isn't it also arbitrary to think that if we could
| explain things in more beautiful ways then it would be a
| deeper understanding or closer to the truth?
| WithinReason wrote:
| The article has some more instances of pysicists naming things:
|
| "The partner of the Higgs, the higgsino."
|
| "The partner of the top quark, the stop squark."
| wongarsu wrote:
| The stop squark is one of the sfermions (the superpartner
| particles of their associated fermions). As such they are all
| sparticles. Some of the other sfermions would be the sup
| squark, the scharm squark, the sstrange squark, the selectron
| or the stau. [1]
|
| In my opinion physicists are great at naming things :D
|
| 1: https://en.wikipedia.org/wiki/Sfermion
| saalweachter wrote:
| It seems kind of seems hipster.
|
| "I'll name the particles something that I can later disavow
| as a joke if people don't like it, so I'm not risking
| myself."
| mbg721 wrote:
| I mean, you only get to use "Particle McParticleFace"
| once.
| Taniwha wrote:
| Pretty sure it's its own anti-particle
| whatshisface wrote:
| What alternative would you propose? Greek naming? Latin?
| jrootabega wrote:
| No, I'm sparticles.
| WithinReason wrote:
| Oh yes, I loved it since the Big Bang and the Very Large
| Telescope!
| pfdietz wrote:
| Those supersymmetric particles have the disadvantage of not
| having any evidence they exist. I am sad for all those
| physics grad students who went into supersymmetry and string
| theory.
| steerablesafe wrote:
| Mandatory SMBC: https://www.smbc-comics.com/?id=1452#comic
| coremoff wrote:
| somewhat related, I think, is the enormous disparity between
| the strength of the strong/week/electromagnetic forces and
| gravity (30 or 40 orders of magnitude); possible indication
| that there's something missing
| tsimionescu wrote:
| Why is this a problem? If the other three forces were
| perfectly equal, or in regular intervals, _maybe_ this would
| have meant something, but the other three forces ' strength
| varies by x, y, z between them. Other than human intuition,
| there is nothing inherently different between x = 2 and x =
| 10^30-40.
| coremoff wrote:
| I don't know that it's a problem, and I'm no expert; my
| understanding is that differences like that can sometimes
| indicate that there's something else at play
| MarkusQ wrote:
| > there is nothing inherently different between x = 2 and x
| = 10^30-40
|
| Fermat begs to differ. :)
| T-A wrote:
| I am so tired of seeing massless neutrinos being described as a
| "prediction" of the Standard Model, and finite neutrino masses as
| beyond-Standard Model physics or even a "mystery". This is
| especially disappointing coming from a supposedly serious
| magazine like Symmetry.
|
| Neutrinos were originally hypothesized in order to solve a
| problem which did not require them to have mass, and for a long
| time after they were actually observed, their measured masses
| remained within error bars straddling zero. It therefore made
| perfect sense to model them as massless.
|
| But to actually include neutrino masses in the Standard Model is
| trivial, and was done long ago.
|
| The most straightforward way to do it is to give them quark-like
| mass terms. This requires introducing a right-handed partner for
| each known (left-handed) neutrino, which some people don't like
| because right-handed particles don't partake in weak
| interactions, and weak interactions are the _only_ (known)
| neutrino interactions (apart from gravity), so you end up with
| undetectable particles.
|
| The main alternative is to use Majorana mass terms, making
| neutrinos their own anti-particles, which some people don't like
| because it deviates from the pattern of all other fermions in the
| Standard Model.
|
| A third way is to say "it's both", typically involving the seesaw
| mechanism, which some people don't like because it requires
| unfashionable GUT-style beyond-Standard Model physics.
|
| Point is, there is neither a failed "prediction" nor a great
| "mystery" here. There is uncertainty about which kind of mass
| term we should use for neutrinos, because the experimentally
| observable differences between the alternatives are really,
| really tiny.
| nxpnsv wrote:
| The mystery part is: what is the correct way to include the
| mass term.
| T-A wrote:
| No mystery at all, you add it to the massless part of the
| Standard Model Lagrangian. :)
| AnimalMuppet wrote:
| If I understand this correctly, the "right hand" means
| antiparticles? Do I have that right?
|
| And if so, then I have two questions.
|
| 1. Antiparticles don't participate in the weak force? So if I
| had antimatter, and I made a nucleus of some kind, then it
| couldn't beta decay? If so, does this say anything about the
| matter/antimatter asymmetry in the universe?
|
| 2. At various times, I have seen references to anti-neutrinos.
| They seemed to say that what made them "anti" was simply that
| the spin was in the opposite direction relative to the
| direction of motion compared to a "regular" neutrino. Were they
| wrong? And if they were right, what about the direction of spin
| should make them unable to participate in the weak force?
| T-A wrote:
| > If I understand this correctly, the "right hand" means
| antiparticles? Do I have that right?
|
| No, it's about chirality:
|
| https://en.wikipedia.org/wiki/Chirality_(physics)
| AnimalMuppet wrote:
| OK, then: Why would chirality determine whether a particle
| can interact with the weak force? (ELI5, probably, or at
| least ELI20, if you can.)
| T-A wrote:
| Ultimately it's an experimental fact - a very surprising
| one when discovered:
|
| https://en.wikipedia.org/wiki/Wu_experiment
|
| In theoretical terms, the equation used to describe all
| massive fermions known at the time (like the electron) is
| built out of four-component quantities called Dirac
| spinors:
|
| https://en.wikipedia.org/wiki/Dirac_spinor
|
| A Dirac spinor can be viewed as composed of two simpler,
| two-component quantities called Weyl spinors:
|
| https://en.wikipedia.org/wiki/Weyl_equation#Weyl_spinors
|
| You can try to describe a fermion using only one Weyl
| spinor, but then it turns out that you can't build mass
| terms (unless you're willing to violate special
| relativity).
|
| The massless equation you can write down with a Weyl
| spinor has two plane wave solutions with opposite
| helicity, left and right. A Dirac spinor combines a left-
| handed and a right-handed Weyl spinor; the mass term of
| the Dirac equation "mixes" them, in the sense that if you
| start out with a Dirac spinor having its left-handed
| component set to 0, the mass term will cause it to grow
| at a rate proportional to mass. If you set the mass to
| exactly zero, you're left with two uncoupled Weyl
| equations, one for the left-handed component, one for the
| right-handed one.
|
| Knowing this, and faced with the experimental fact that
| weak interactions make a distinction between left and
| right, you write down separate weak interaction terms for
| the left- and right-handed components of your Dirac
| spinors. Eventually it turns out that the simplest
| choice, having only the left-handed components
| participate in those interactions, is the best fit to
| experiment:
|
| https://en.wikipedia.org/wiki/Weak_isospin#Relation_with_
| chi...
|
| -\\_(tsu)_/-
| AnimalMuppet wrote:
| Thank you for a clear, detailed response. (It would be
| more clear if I understood the math behind spinors...)
|
| So, returning to a previous question: If I understand
| this correctly, it means that if we have a kind of
| nucleus that undergoes beta decay, and we built the exact
| same nucleus except out of antimatter, it would _not_
| undergo beta decay. Is that correct?
|
| Has anyone actually done that experiment? Or is it beyond
| our ability to construct things out of antimatter?
| T-A wrote:
| > if we have a kind of nucleus that undergoes beta decay,
| and we built the exact same nucleus except out of
| antimatter, it would not undergo beta decay. Is that
| correct?
|
| No. Until 1964 you would have been told that applying CP,
| i.e. the combination of C transformation (charge
| conjugation, i.e. change the signs of all charges) and P
| transformation (parity, i.e. swap left and right) would
| result in exactly the same decay rate. You would get
| anti-neutrinos (which are right-handed) instead of
| neutrinos, but that would be the only difference.
|
| Then it turned out that CP symmetry is _also_ violated by
| weak interactions, though far from as neatly as just P:
|
| https://en.wikipedia.org/wiki/CP_violation
| SaberTail wrote:
| This is more of an empirical thing. We observe effects
| such as parity violation that can be best explained by an
| interaction that only works on left-handed particles.
| goatlover wrote:
| So the theoretical thing would be to account for the
| observed effects.
| 0PingWithJesus wrote:
| I think you're correct to say a lot of people simplify what the
| problem is with neutrino mass. In principle it seems like there
| is no problem, you just add a mass term for the neutrino just
| like any other particle. Just b/c at first we didn't expect
| that term to be there doesn't mean it's a problem to now, or
| that original expectation was all that meaningful. And again,
| as you point out, there are a couple of potential ways to add
| that mass term in, either the "normal" way with a right handed
| neutrino, or with some fancy see-saw majorana term, or some
| combination thereof.
|
| The issue is though, right now the standard model is at least
| ambiguous in terms of the majorana mass term. If it ends up the
| neutrino gets its mass from only the "normal" mass term, then
| why doesn't it have a majorana mass term? There's no current
| symmetry that says there can't be a majorana mass? If the
| neutrino's majorana mass is zero, then you'd probably have to
| introduce a symmetry into the standard model that says majorana
| particles can't exist.
|
| But if the neutrino does end up having a non-zero majorana mass
| term then that means the neutrino is a majorana particle, and
| can undergo lepton number violating processes (e.g.
| neutrinoless double beta decay). Again, that's new physics.
|
| So no matter how you give the neutrino mass, you're gonna have
| to modify the standard model in some "significant" way to
| accommodate. Either by specifically saying majorana particles
| can't exist, or by allowing for lepton number violating
| processes.
|
| Now you could say, well then it might the case that majorana
| particles don't exist b/c that would require lepton number
| violating processes, so I don't need to introduce a new
| symmetry, I can just take advantage of one that's already lying
| around. That might be a valid claim to make...I'm not sure. I
| think the issue with that comes down to the difference between
| lepton number a global vs accidental symmetry in the standard
| model.
| supergarfield wrote:
| > This requires introducing a right-handed partner for each
| known (left-handed) neutrino, which some people don't like
| because right-handed particles don't partake in weak
| interactions, and weak interactions are the only (known)
| neutrino interactions (apart from gravity), so you end up with
| undetectable particles.
|
| I'd be curious to hear more about this. What mechanism forces
| you to add right-handed partners? Is it some conservation
| property? Are calculations too difficult without them?
|
| Maybe it's also not clear if there really is a difference
| between saying "right-handed neutrinos exist but are
| undetectable" and "right-handed neutrinos are fake particles
| added for ease of modeling".
|
| Edit: Wikipedia also says
|
| > The neutral-current Z^0 interaction can cause any two
| fermions in the standard model to deflect: Either particles or
| anti-particles, with any electric charge, and both left- and
| right-chirality, although the strength of the interaction
| differs.
|
| So could right-handed neutrinos be detected this way?
| T-A wrote:
| > What mechanism forces you to add right-handed partners?
|
| A Dirac mass term (the kind used for all other Standard Model
| fermions) involves both left-handed and right-handed
| particles:
|
| https://en.wikipedia.org/wiki/Sterile_neutrino#Mass
|
| So you can't have one without both. (BTW, the linked section
| says "there are no Dirac mass terms in the Standard Model's
| Lagrangian", but it should really say that the Dirac mass
| terms in the Standard Model Lagrangian arise as a consequence
| of the Higgs mechanism.)
|
| > Wikipedia also says
|
| I can't find that quote, but I guess it's about
| experimentally observed particles. It would not apply to a
| right-handed neutrino:
|
| https://en.wikipedia.org/wiki/Sterile_neutrino#Properties
| not2b wrote:
| I've seen another argument, but I lack the competence to
| assess its validity: if a (left-handed) neutrino has mass,
| it moves at less than the speed of light, which means you
| can pass it and look back at it. You'd then see it as
| having reversed spin. But that might be based on a
| classical physics analogy that doesn't hold.
| T-A wrote:
| You're thinking about helicity, not chirality:
|
| https://en.wikipedia.org/wiki/Neutrino#Chirality
| SaberTail wrote:
| That's correct. The more jargon-y way to say it would be
| that for massive particles, helicity isn't Lorentz
| invariant.
|
| It's an approximation that helicity equals chirality
| (which is what matters for weak force interactions), but
| this approximation is pretty good for particles moving
| close to the speed of light (which neutrinos tend to do,
| due to their low mass)
| AnIdiotOnTheNet wrote:
| > This requires introducing a right-handed partner for each
| known (left-handed) neutrino, which some people don't like
| because right-handed particles don't partake in weak
| interactions, and weak interactions are the only (known)
| neutrino interactions (apart from gravity), so you end up with
| undetectable particles.
|
| For anyone else wondering: yes, this does make said right-
| handed (aka sterile) neutrinos a candidate for dark matter,
| assuming some of them are much heavier than their left-handed
| counter parts to account for the 'cold' properties of dark
| matter that we observe.
| bopbeepboop wrote:
| This is wrong.
|
| We know that either:
|
| a) there's mysterious undetectable particles, or
|
| b) that something beyond the standard model is happening, as in
| your second and third points.
|
| There's a failed "prediction" that all fermions have similar
| mass terms, and that failure suggests either something strange
| (undetectable particles), something strange (fermions without
| consistent mass mechanisms) or something strange (novel
| physics).
|
| I think that qualifies as a mystery.
| Iwan-Zotow wrote:
| "either something strange (undetectable particles)" There is
| nothing strange here. Undetectable in this context means it
| would be only detectable by gravitation detectors - all
| masses/energies have gravitation changes.
| unholiness wrote:
| Honest question from a physics novice: Would it be wrong to say
| the same is roughly true of all of the first 4?
|
| I have heard it is plausible that Dark Matter is merely another
| particle that fits in the standard model. I've heard it
| plausible that Dark Energy is e.g. a WIMP or other new particle
| in the standard model. And, on more-matter-than-antimatter, I
| imagine _some_ explanations of baryon asymmetry could come from
| outside the standard model but others (boundary condition,
| mirror anti-universe) would be fully standard-model-compatible,
| right?
|
| That would leave only #5 as a mystery: Why is gravity as we
| know it in general relativity so different (weaker) than the
| force that a standard-model graviton would predict?
| T-A wrote:
| > I have heard it is plausible that Dark Matter is merely
| another particle that fits in the standard model. I've heard
| it plausible that Dark Energy is e.g. a WIMP or other new
| particle in the standard model.
|
| Whoever told you that was getting dark matter and dark energy
| mixed up.
|
| Dark matter could be "another particle", possibly a sterile
| neutrino:
|
| https://en.wikipedia.org/wiki/Sterile_neutrino#Sterile_neutr.
| ..
|
| Dark energy however is definitely something else. WIMPs in
| particular are hypothetical dark _matter_ particles:
|
| https://en.wikipedia.org/wiki/Weakly_interacting_massive_par.
| ..
| mellosouls wrote:
| (2018) though I don't expect much has changed...
| redis_mlc wrote:
| > Five mysteries the Standard Model can't explain
|
| And a good thing, too.
|
| Otherwise those juicy big-science grants would disappear!
| b-x wrote:
| What about the existence of magnetic monopoles?
| aardvark179 wrote:
| Well the standard model doesn't predict them, and apart from
| one detection that has never been reproduced we've never
| detected any pre-existing ones or any created in a particle
| accelerator.
| [deleted]
| b-x wrote:
| The standard model doesn't predict the graviton neither,
| nonetheless, they mentioned it in the article.
|
| Does the SM theorize about the impossibility of the
| monopoles' existence?
| galcerte wrote:
| We have detected the effects of gravitons (...if it's
| gravitons and not something else) at macroscopic scales,
| however we have not done the same with monopoles. So that
| comparison is not apples to apples.
|
| I have not heard anything about the SM predicting them
| being impossible, but I assume it does given that I haven't
| heard anything about the subject. Source: I have a master's
| in physics and a friend of mine did his bachelor's thesis
| in monopoles in classical electrodynamics (albeit modified)
| and his master's in quantum ones, so he would've told me if
| he knew.
|
| However, if any GUT theory we have come up with is correct
| (because a few exist), then that does imply the existence
| of monopoles.
| auntienomen wrote:
| Gravitons are a universal prediction, so one doesn't get
| any credit for predicting them. _Any_ low-energy quantum
| field theory approximation to gravity will have them, so
| long as it looks like GR at large enough distance scales.
| sesm wrote:
| 2, 3 and 4 are not Standard Model problems, but cosmological
| problems. There are cosmological theories that explain them by
| using only General Relativity without any changes to particle
| physics. For example, you can check out Nick Gorkavyi's
| cosmological papers:
|
| https://pos.sissa.it/335/039/
|
| https://academic.oup.com/mnras/article/476/1/1384/4848298
|
| https://academic.oup.com/mnras/article/461/3/2929/2608669
|
| https://arxiv.org/abs/2110.10218
|
| https://www.sao.ru/Doc-k8/Science/Public/Bulletin/Vol76/N3/A...
| (this one is available only in Russian for now)
| kloch wrote:
| They forgot at least one mystery: What determines the fermion
| mass spectrum and specific mass vlaues? Why do these particle
| masses take such seemingly random values?
|
| Related: Why are these masses so much smaller than the Planck
| mass? For comparison, the electric charge is sqrt(alpha_em) or
| ~1/11th the value of the Planck charge.
| streamofdigits wrote:
| The problem is that from an experimental / observational
| technologies perspective we have been for many decades now in
| some sort of "evidence desert" that pushes against fundamental
| technology boundaries and that is not conducive to solving big
| "mysteries".
|
| Unifications, re-interpretations, new conceptualizations (new
| forces etc) are the mental tools through which we solve previous
| "mysteries" (and create new ones). Right now there are alive more
| physicists than ever and even a tiny piece of important news
| could lead to a revolution - in like a couple of years. But what
| you really want is a firehose of new data points, "a new window".
| This has not happened and it may not happen for generations (for
| the attentive reader: gravitational waves are at the very, very
| edge of the detectable).
|
| As Feynman might say, the Universe doesn't owe us a continuous
| stream of gee-wow moments
|
| But if I had to bet _where_ the breakthrough might come from I 'd
| say it would probably be cosmology rather than elementary
| particles...
| jjk166 wrote:
| I've recently heard a rather interesting and optimistic take on
| this. Since we have had so many brilliant minds looking in so
| many places for new physics and still have not seen evidence of
| it, that suggests whenever we do find new physics, it will have
| to be so bafflingly strange that all these brilliant people
| could never imagine it. It may very well be a bigger paradigm
| shift than the jump from classical to modern physics.
| streamofdigits wrote:
| Yep, that makes sense. It doesn't give us a timescale for
| when such a "jump" might happen but suggests that it could be
| "big" in the context of our heretofore discoveries
|
| My best guess at timescale (following up on the cosmology
| theme) has to do with our rate of utilizing the inner solar
| system as a clean and quiet laboratory for ultra sensitive
| observations and experiments (whether LISA) or extremely
| sensitive telescopes or any other probes.
|
| So be patient for a few more decades :-)
| snowwrestler wrote:
| It seems crazy to say that we have not seen evidence for new
| physics when the size estimates of dark matter and dark
| energy account for about 95% of known energy in the
| observable universe. How is that not evidence for new
| physics?
|
| If our physical theories cover only about ~5% of what we
| observe... that seems like a bit of an issue, no matter how
| accurately they model that 5%.
| jjk166 wrote:
| Neither dark matter nor dark energy are new physics. We
| don't know exactly what particle or combination of
| particles is responsible for dark matter, but there's not
| yet evidence that dark matter actually is composed of
| something outside the standard model. Dark energy is,
| despite the name, well explained by general relativity.
| When people talk about new physics, they're referring to
| things that change our understanding of how the universe
| works on a fundamental level. By comparison to biology,
| these are like newly discovered species - of course they're
| interesting but our understanding of nature is
| unchallenged.
| cjfd wrote:
| The neutrino mass thing is much less a surprise than the rest.
| Neutrino mass always was quite possible as an optional add-on.
| Basically, the situation for the quarks, where all six have mass,
| can be copied to apply to the leptons as well.
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