Strange

I agree. However, that is not the same as it no longer holding true. And, as far as I know, there have been no extensions since the mid-70s when QCD was added. What is silly about asking you for an example or to clarify what you mean?

That implies that there are observations that do not fit in the standard model. Can you give an example?

I am not sure, but I thought that this "missing" baryonic matter was already taken into account (I mean, assumed to be there). But if it turns out to be largely outside galaxies, that might mean we need more dark matter not less!

Not assuming anything. The answer is we don't know. Among the classes of possibilities are WIMPs and MACHOs: https://en.wikipedia.org/wiki/Weakly_interacting_massive_particles https://en.wikipedia.org/wiki/Massive_compact_halo_object There are many other ideas. Energy is a property of things, so it can't be just energy. Not sure what you mean by a "left over" but I think that in most models dark matter has existed for as long as normal matter. I don't think so. The speed is so close to the speed of light that it is within the error bounds. Or maybe they do travel at the speed of light and this indicates something else wrong with the model. I don't think that either of those is the case. Gravitons would be the quantum of gravitational waves in the same way that photons are the quantum of EM waves. And gravity would be mediated by virtual gravitons in the same way that electromagnetic forces are mediated by virtual photons. I think there are models which have both modified gravity plus dark matter. But I don't know any more than that ...

Nope.

Sounds like a good summary to me. BTW, I had never looked at the Wikipedia page on the standard model before. It has a very neat diagram summarising all the known interactions of particles: https://en.wikipedia.org/wiki/Standard_Model

I'm not sure that there is really any evidence for or against it. It is a possible consequence of some big bang models. One thing I agree with Dubbelosix about is that it is (currently) unfalsifiable. But I don't think that means it should be discounted or considered to be wrong. (I am actually not particularly interested in it for that reason, though.) It might be that a quantum theory of gravity sheds more light on the early universe. That might make a multiverse model more or less plausible. I think it is one of those things we can never have direct evidence of, but it might seem be an inevitable consequence of some future theory. Or the reverse. (It is all too speculative for me to care much either way!)

So, from that, I can only conclude that you don't have any examples of the standard model being changed or extended since the addition of quarks. I just checked on Wikipedia and its (admittedly very brief) history section has the last update to the standard model being the addition of QCD to explain the behaviour of quarks. Then it has a link to "physics beyond the standard model" which includes things like supersymmetry, preons, string theory, etc. So I am confused about where our difference of opinion (if any) lies.

Well, I'm sorry you feel that way. But I can't really understand why you do. If my knowledge of the standard model is lacking, then I am interested in learning more. So if the standard model has changed in ways I am not are of then I would like to learn about it. We both seem to agree that the standard model cannot be complete. But beyond that, I seem to have misunderstood several of your statements. So I am also trying to understand where I have gone wrong and what you meant. For example, I initially thought you meant that there were things that had been discovered that were not part of the standard model. I see know that this was just a misunderstanding on my part. Then I thought you were saying that if you predict something outside of the standard model then you are predicting something that can't exist. But obviously, I was wrong about that as well. So I am not really sure where we stand. I would appreciate some examples of ways the standard model has changed or been extended since the discovery of quarks (even the Higgs mechanism is earlier than that) as it seems I have missed some stuff.

Isn't that about the Many Worlds interpretation, not the multiverse?

Huh? Supersymmetry predicts a number of particles that are not part of the standard model. There are other hypothetical ideas like axons. So it is quite possible to predict the existence of things outside the standard model. That doesn't mean they "shouldn't exist in nature". What an odd thing to say. Could you provide some examples then. As this is so obvious to you, that shouldn't take much time. (And why would I say you were lying, when you haven't provided any examples yet.)

There are also cultural factors. For example some cultures or religions do not like the idea of "mutilating" the body after death by removing organs.

Possibly a complete misunderstanding of your use of the word "discrepancy". However, there is absolutely nothing observed that is outside of the standard model and nothing that has caused the standard model to be revised since, I think, the addition of quarks (one of the major paradigm shifts Have lived through!). I may be wrong, but your one example of "discrepancy" doesn't seem to require any change to the standard model. Indeed. But (again, as far as I know) none of the possible extensions have predicted anything that has been found. Everything discovered to date is within the standard model. Hopefully something will be discovered soon that forces the standard model to be revised or extended. (My time is running out, apart from anything else!)

I don't think anyone thinks the standard model is all there is. Because of dark matter, if nothing else. But so far, there is no evidence as to what might be beyond the standard model. So do you just mean the standard model has been extended to include new observations? If so, that is how science proceeds. (Is English not your first language? I would be surprised because it appears perfect but you seem to be using "discrepancy" and "divergence" in a slightly idiosyncratic way.) But actually, I'm not even sure that is true. The existence of pentaquark was predicted long before they were seen. I am not aware of anything that has been found that was not predicted as part of the standard model. Many physicists are very frustrated that nothing as been found to "break" or extend the standard model. Many were hoping that the Higgs wouldn't be found. Or that it would turn out to have properties different than expected. People still hope to find something that will support some for of supersymmetry but instead more and more constraints are being placed on any extension to the standard model.

You started off saying there were discrepancies in the standard model and claimed the pentaquark was not part of the model (when it obviously is). Then you said there is nothing inconsistent. Maybe "discrepancy" and "inconsistent" mean very different things to you. Perhaps you need to explain what you mean. And provide some actual examples of these "discrepancies". Or are they all, like the pentaquark, due to your lack of knowledge?

How do the Friedmann equations relate to dark matter? Doesn't seem consistent with what? We already know of particles which do not interact via the electromagnetic force. Why would it be strange or inconsistent if there were others? There several pre-existing hypotheses that could account for dark matter.

So, which is it?

Just a guess from this: https://en.wikipedia.org/wiki/Galaxy_rotation_curve (see the error bars on the graph)

But it isn't. The difference between calculated mass distribution and the observed mass is enormous: a factor of 5. The error bounds will be a few percent, at most, fractions of a parent in some cases.

"the possibility of five-quark particles was identified as early as 1964 when Murray Gell-Mann first postulated the existence of quarks.[3] Although predicted for decades, pentaquarks have proved surprisingly difficult to discover and some physicists were beginning to suspect that an unknown law of nature prevented their production.[4]" https://en.wikipedia.org/wiki/Pentaquark Seems to be pretty much part of the standard model.

OK. So not logic as it is used in philosophy, mathematics or science. Not much.

What does "logical sentiment" mean? Are you using the word logic in the popular sense of "it makes sense to me"? In which case it has pretty much zero value. And what is an "action theory"?

Can you provide some examples or some sort of supporting reference for this?

An argument from incredulity is not very compelling, whoever it comes from. Also, you may be mixing up the multiverse hypothesis (or hypotheses) with the Many Worlds interpretation of quantum theory (which is, of course, indistinguishable from the Copenhagen interpretation or indeed any other).

https://en.m.wikipedia.org/wiki/Cheese