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A new experiment casts doubt on the leading theory of the nucleus

quantamagazine.org

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Re: A new experiment casts doubt on the leading theory of the nucleus

#41

Post by Keyframe »

marcosdumay wrote: post #33
houston_Euler wrote: post #25

Earlier quoted context omitted.

Can you point to some evidence for the claim that "a molecule of water is lighter than the oxygen and two hydrogen atoms that went into making it?" I could understand the atoms sharing electrons, but just want to make sure I'm understanding you correctly, because you said it's unexplained.

You mean experimental evidence? I don't think our mass measurements are that precise. Just to be clear, that statement is very well accepted physics, and we have plenty of evidence of bounding energy changing the mass of things on the more energetic reactions (the nuclear ones). It would be incredibly surprising (in "redo all of physics" surprising) if it didn't hold for chemical reactions too, but I don't think anyb…

You mean experimental evidence? I don't think our mass measurements are that precise.

You don't need to weigh individual atoms or molecules to take measurement!

Just to be clear, that statement is very well accepted physics, and we have plenty of evidence of bounding energy changing the mass of things on the more energetic reactions (the nuclear ones). It would be incredibly surprising (in "redo all of physics" surprising) if it didn't hold for chemical reactions too, but I don't think anybody has evidence.

Not sure I follow your direction here. Seems to be a conflation of three separate things, not necessarily compatible with each other. In classical physics mass and charge (of a particle) are different properties. One defines how particle behaves in response to forces, the other how it interacts with em fields. That's one. The other, if we go into relativistic physics, there's mass-energy equivalence (as stated by einstein)... however, charge itself isn't a form of energy, BUT charged particles can have energy associated with their electric fields that would contribute, in a sense, to the overall mass-energy of a system (which is usually ignored unless we're talking sub-atomic particles or high-energy physics). That's two. And then there's binding (not bounding) energy which represents the amount of energy required to split a system of particles into its non-interacting components (such as, in context of nuclear physics, splitting a nucleus into protons and neutrons).. or you've meant electron binding energy which represents amount of energy needed to remove an electron from an atom.. that'd be a third.

Re: A new experiment casts doubt on the leading theory of the nucleus

#43

Post by exmadscientist »

jjtheblunt wrote: post #34
andreareina wrote: post #7

Earlier quoted context omitted.

The standard model has a number of free parameters [1] but the results of calculations are pretty sensitive to them, and this is what predicted (not just explained post-hoc) the Higgs. It's not incorrect to say there's curve fitting involved, but it severely understates the magnitude of the achievement that is the standard model, and its success in explaining everything that underpins everyday life[2], as well as mos…

If it explains everything then why are experiments still ongoing? What is left to explain?

To oversimplify: the Standard Model is pretty great when you've got two particles. As soon as there's three, it's too hard to calculate most things people are interested in. Oh, or gravity. Gravity's a problem too.

Re: A new experiment casts doubt on the leading theory of the nucleus

#44

Post by consilient »

jjtheblunt wrote: post #34
andreareina wrote: post #7

Earlier quoted context omitted.

The standard model has a number of free parameters [1] but the results of calculations are pretty sensitive to them, and this is what predicted (not just explained post-hoc) the Higgs. It's not incorrect to say there's curve fitting involved, but it severely understates the magnitude of the achievement that is the standard model, and its success in explaining everything that underpins everyday life[2], as well as mos…

If it explains everything then why are experiments still ongoing? What is left to explain?

"everything that underpins everyday life" is not everything. A more precise way to put it would be that we understand physics at the energy scales we've been able to probe.

Re: A new experiment casts doubt on the leading theory of the nucleus

#45

Post by chaxor »

jiggawatts wrote: post #16
jfengel wrote: post #9

Earlier quoted context omitted.

But relativity explains GPS. And the two theories together explain practically everything to insane levels of precision. The only time they go wrong is when they both operate at once, in a narrow range around black holes or the very earliest universe.

General Relativity doesn’t end just above the atmosphere and quantum mechanics ought to apply to everything, not just experiments. The current microscopic models don’t even attempt to explain how a molecule of water is lighter than the oxygen and two hydrogen atoms that went into making it. Oh sure, we can wave our hands at it and invoke the mass-energy relation from GR, but this doesn’t “pop out” of the Standard Mod…

Ok.

Suggest a better theory so you can pat yourself on the back then.

Re: A new experiment casts doubt on the leading theory of the nucleus

#46

Post by Sakos »

jdkee wrote: post #30
houston_Euler wrote: post #25

Earlier quoted context omitted.

Can you point to some evidence for the claim that "a molecule of water is lighter than the oxygen and two hydrogen atoms that went into making it?" I could understand the atoms sharing electrons, but just want to make sure I'm understanding you correctly, because you said it's unexplained.

Per our new electronic friend: " The weight of a molecule of water (H2O) is the sum of the weights of the two hydrogen atoms and one oxygen atom that compose it. Here are the atomic weights of these elements: Hydrogen (H): Approximately 1 atomic mass unit (amu) Oxygen (O): Approximately 16 amu So for a molecule of water: 2 Hydrogen atoms: 2 * 1 amu = 2 amu 1 Oxygen atom: 16 amu Adding these together gives a total of…

Okay, somebody explain these downvotes, because afaik none of these statements in this comment or the other downvoted comments about the mass of water are incorrect. Somebody make it make sense.

Re: A new experiment casts doubt on the leading theory of the nucleus

#47

Post by tsimionescu »

Sakos wrote: post #46
jdkee wrote: post #30

Earlier quoted context omitted.

Per our new electronic friend: " The weight of a molecule of water (H2O) is the sum of the weights of the two hydrogen atoms and one oxygen atom that compose it. Here are the atomic weights of these elements: Hydrogen (H): Approximately 1 atomic mass unit (amu) Oxygen (O): Approximately 16 amu So for a molecule of water: 2 Hydrogen atoms: 2 * 1 amu = 2 amu 1 Oxygen atom: 16 amu Adding these together gives a total of…

Okay, somebody explain these downvotes, because afaik none of these statements in this comment or the other downvoted comments about the mass of water are incorrect. Somebody make it make sense.

I believe this one is downvoted for quoting Chat GPT. The other one is downvoted not so much for the claim about water molecule mass, but because of the combative tone and feeling that it is challenging established physics in a somewhat shallow way, most likely.

Re: A new experiment casts doubt on the leading theory of the nucleus

#48

Post by garfieldandthe »

jiggawatts wrote: post #16
jfengel wrote: post #9

Earlier quoted context omitted.

But relativity explains GPS. And the two theories together explain practically everything to insane levels of precision. The only time they go wrong is when they both operate at once, in a narrow range around black holes or the very earliest universe.

General Relativity doesn’t end just above the atmosphere and quantum mechanics ought to apply to everything, not just experiments. The current microscopic models don’t even attempt to explain how a molecule of water is lighter than the oxygen and two hydrogen atoms that went into making it. Oh sure, we can wave our hands at it and invoke the mass-energy relation from GR, but this doesn’t “pop out” of the Standard Mod…

> We have a long way to go before we can par ourselves on the back and claim to truly understand what’s going on.

This is a misconception of scientific endeavour in general and of physics in particular. All models are approximations of reality. We have a theory that is consistent with experimental observations, then we make observations with which the theory is not consistent anymore and we develop a new theory that explains those new observations as well, and so on. We will never have an "exact" model, whatever that even means. But we have models that have limitations that are far beyond what's relevant for most people's life.

At many points in time, we could pat ourselves on the back. The heliocentric model. Newtons model. General Relativity. The Standard Model. All these models were important steps forward and led us to where we are today, which is absolutely astonishing. No, we don't have a full theory explaining everything, but we never will.

Re: A new experiment casts doubt on the leading theory of the nucleus

#49

Post by fsh »

marcosdumay wrote: post #33
houston_Euler wrote: post #25

Earlier quoted context omitted.

Can you point to some evidence for the claim that "a molecule of water is lighter than the oxygen and two hydrogen atoms that went into making it?" I could understand the atoms sharing electrons, but just want to make sure I'm understanding you correctly, because you said it's unexplained.

You mean experimental evidence? I don't think our mass measurements are that precise. Just to be clear, that statement is very well accepted physics, and we have plenty of evidence of bounding energy changing the mass of things on the more energetic reactions (the nuclear ones). It would be incredibly surprising (in "redo all of physics" surprising) if it didn't hold for chemical reactions too, but I don't think anyb…

The mass ratios of charged particles, such as atomic and molecular ions, can be measured incredibly accurately in Penning traps. Some of the most accurate comparisons are between the mass-3 ions ³He⁺, HD⁺, T⁺, and H₃⁺. Of these, only H₃⁺ has long-lived excited states, and the different excitation energies are clearly resolved in the mass comparisons [1]. The binding energies are much larger and have to be taken into account in the comparisons.

[1] https://doi.org/10.1103/PhysRevLett.120.143002

Re: A new experiment casts doubt on the leading theory of the nucleus

#50

Post by azalemeth »

lilgreenland wrote: post #14
jfengel wrote: post #9

Earlier quoted context omitted.

But relativity explains GPS. And the two theories together explain practically everything to insane levels of precision. The only time they go wrong is when they both operate at once, in a narrow range around black holes or the very earliest universe.

They also go wrong with large scale phenomena like inflation, dark matter, and dark energy.

There's also the problem of fine tuning -- why is the fine structure constant roughly 1/137? If it were different from its current value by a tiny amount, the universe as we know it wouldn't exist. Is the anthropocentric principal the only explanation we have -- it has the value it has because it produces a universe in which we're able to observe it?

And I guess less formally there's also the problem of complexity: condensed matter physics exists because trying to solve the standard model for a solid directly is both incredibly infeasible (think "cost of flipping bits in the calculation far extends that of all matter in the observable universe") and fails to capture the emergent phenomena in a natural way.

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