Is the standard model only descriptive lacking understanding of underlying structure?

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I was asked this question by someone else and wondered if I could get better answers here:


Is it fair to say that the standard model for matter is basically descriptive, without any underlying understanding of what causes its structure?

Can it be compared it to the periodic table of elements BEFORE the discovery of the modern atomic model (nucleus plus electrons in shells) and quantum mechanics. Once one has the Schroedinger equation, plus spin, the periodic table becomes a trivial result, that can be derived in a few hours. But before one has the right fundamental equations, the chemical elements are just a mess of phenomena, some of which have some similarities.

So are we are at the very point in physics where we were 100 years ago in chemistry? i.e.. we have the elements, we can put them in a table and we can even do "chemistry" with them, but what they really are eludes us. Eventually, we will find the correct equations. But is the standard model of high energy physics really it?

Also take at the look at its full Lagrangian and tell me if you really expect this to be the fundamental equation of the universe? even without gravity!
 
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  • #2
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On reflection this question is dealing with the standard model in particle Physics which is not the standard model we talk about in Cosmology.

However, I believe progress was made in understanding the structure of matter with the theory of Quarks and their forces carriers and interactions. I am not sure if this means that we now understand the structure of matter, or if this is still just one more layer of being descriptive. That is the best answer that I can give for now.
 
  • #3
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This is a question of philosophy more than Cosmology, the topic where you've started this thread.

Personally, I am not convinced that "underlying understanding" is independent from the "descriptive" model. The better the model, the better your understanding of the processes it describes. There is a feeling of safety and completeness that comes with understanding of deep laws of nature, and it is wonderful.

On the other hand, it goes against the philosophy of science to resist new ideas because you feel good about ideas you've committed to, emotionally. This is why I think it dangerous to focus on "underlying understanding" instead of perusing truth by model dependent realism.

Too many times I have heard argument for an otherwise weak theory because it satisfies the emotional need for "understanding". For example, someone was espousing the idea of entropic gravity as being true chiefly because it provided an "underlying understanding" of gravity.

I can think of a different but related question: Will the successor of the Standard Model be a modification, or complete renovation?

A successful unification of the Standard Model with General Relativity would, I suspect, look radically new.
String theory and LQG, two of our best attempts to date, are a good example.
 
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I agree this question could be equally relevant in the High Energy forum, Cosmology Forum and Philosophy forums. I thought it would be interesting to all though especially the periodic table analogy.
It is also interesting that we are facing kind of similar issues at both the infinite and infinitesimal scales of the universe.
 
  • #5
Chronos
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Some think quantum theory is more squishy than GR. I happen to agree.
 
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Chronos, so you think that QT yields easily to pressure or weight, and is not as firm as GR?



gendou2, so the question really is do we lack the underlying understanding of what gives matter its structure?

We thought we had answered this at the atomic level, then we found the nuclear level, and now we have the fermion (quarks and leptons) level (which cannot be observed). At each level of abstraction we found there was something more, perhaps this final level of abstraction is the last? If so perhaps this question about what gives matter structure cannot ever be answered and at this final level of abstraction we are left only with descriptive models?

What are fermions and what causes the 24 fermions to be different from each other? How can a point like anything have structure? Is this a reason why other dimensions than the three large ones that we know are being proposed?

http://en.wikipedia.org/wiki/Fermion
http://en.wikipedia.org/wiki/Boson


http://en.wikipedia.org/wiki/Mass_in_special_relativity
http://en.wikipedia.org/wiki/Mass_in_general_relativity
 
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  • #7
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do we lack the underlying understanding of what gives matter its structure?
Not at all! The structure of matter is very well understood.
Read up on Quantum Electrodynamics.

perhaps this final level of abstraction is the last?
You've gone down another philosophically dangerous road by asking about a "final level".
A smart scientist will not get married to one theory, till death do they part.
There is no "final" theory, no matter the title of Weinberg's book.
Sure, we have reason to believe new physics may be hiding down to, but not below the plank length.
Even if we reach this experimental limit, there may be things yet to unify.

now we have the fermion (quarks and leptons) level (which cannot be observed)
I object to your classification of quarks and leptons as "unobservable".
The directness of evidence doesn't matter as much as how well it supports theory.
Indirectness of measure can be a source of error, but is philosophically irrelevant.
We're used to indirect measures, photographic plates and bubble chambers.

What are fermions and what causes the 24 fermions to be different from each other?
You ask what fermions are, but give a link to the wiki page, so I won't answer that part.
What makes them different, also seen on the wiki page, is their mass, charge, spin, and name.
Where you find unexplained complexity you may find new physics, it's a good place to look.
This is one of the compelling arguments for string theory, that it accounts the fermions properties.

How can a point like anything have structure?
In the spacial system describing the point, it can't have further structure.
Though, a thing we model as a point today may be found to have tiny hidden structure tomorrow.

Is this a reason why other dimensions than the three large ones that we know are being proposed?
<joke>No. String theorists just added 6 extra dimensions to get more grant money.</joke>
 
  • #8
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Thanks gendou2, you have a singular wit. So you dont like string theory then? :)

So what could possibly give these 24 fermions such different properties? I suspect more structure..
 
  • #9
D H
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Is it fair to say that the standard model for matter is basically descriptive, without any underlying understanding of what causes its structure?
No. That is an incredibly unfair assessment.

Can it be compared it to the periodic table of elements BEFORE the discovery of the modern atomic model (nucleus plus electrons in shells) and quantum mechanics. Once one has the Schroedinger equation, plus spin, the periodic table becomes a trivial result, that can be derived in a few hours. But before one has the right fundamental equations, the chemical elements are just a mess of phenomena, some of which have some similarities.
I disagree. It was the growing particle zoo of the 1940s-1970s that could be compared to the periodic table, not the standard model. In fact, that growing particle zoo had a lot less structure than did even the first stabs at a periodic table. It was the standard model that brought it all together.

Is there more? Probably. At least that is the hope that drives string theory. But don't knock the standard model. The simplifying and unifying picture that it provides to particle physics is incredibly powerful and incredibly deep. In my mind, it is a much deeper theory than is general relativity.
 
  • #10
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So, you don't like string theory, then?
I have nothing against string theory.
Didn't you get my joke?

What could possibly give these 24 fermions such different properties?
Theory tells us what we can observe, and we observe the masses of the 24 fermions.
These different properties come from nature, in the context of the Standard Model.
I worry you won't be satisfied until you have a theory with zero free parameters.
There is no reason to expect so simple a theory as to have no free parameters at all.

I suspect more structure...
Like I said before, the origin of the particle generations is a good area to research.
There may be a good explanation, or there might not.
See if you can come up with one!
 
  • #11
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I was asked this question by someone else and wondered if I could get better answers here:

Is it fair to say that the standard model for matter is basically descriptive, without any underlying understanding of what causes its structure?

Can it be compared it to the periodic table of elements BEFORE the discovery of the modern atomic model (nucleus plus electrons in shells) and quantum mechanics. Once one has the Schroedinger equation, plus spin, the periodic table becomes a trivial result, that can be derived in a few hours. But before one has the right fundamental equations, the chemical elements are just a mess of phenomena, some of which have some similarities.
What you say about the periodic table of chemistry is plain wrong:

How Good is the Quantum Mechanical Explanation of the Periodic Table?, Journal of Chemical Education, 75, 1384-1385, (1998). Scerri, Eric.

Has the Periodic Table Been Successfully Axiomatized? Erkentnnis, 47, 229-243, (1997). Scerri, Eric.

See also his well-known book

https://www.amazon.com/gp/product/0195305736/?tag=pfamazon01-20

So are we are at the very point in physics where we were 100 years ago in chemistry? i.e.. we have the elements, we can put them in a table and we can even do "chemistry" with them, but what they really are eludes us. Eventually, we will find the correct equations. But is the standard model of high energy physics really it?

Also take at the look at its full Lagrangian and tell me if you really expect this to be the fundamental equation of the universe? even without gravity!
Evidently, nobody claims the Standard Model to be the last word and several extensions of it are being worked since the 20th century.
 

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