Is the Pursuit of a Grand Unified Theory Skipping Essential Steps?

[quantumkiko]

I was wondering why physicists already bother on searching for a grand unified theory if they haven't even unified the electroweak with the strong force (electrostrong) yet. Shouldn't we take things one step at a time? I don't like the idea that we are jumping this "gap" in search for one that unifies all the four forces already. So, aren't we assuming too much by making this jump?

 

[Vanadium 50]

Quantumkiko-

"You guys are doing it all wrong" is a claim that many people would find disrespectful and arrogant. If you have a PhD in physics, you're free to pursue any line of research you feel might be fruitful. If you don't have one, you might consider the possibility, remote as it might be, that you don't know more about theoretical physics than the entire rest of the community and that maybe, just maybe, those who spent years studying the field might, just might, know what they are doing.

Second, your premise is completely untrue. There have been many, many attempts at unifications that do not involve gravity. This goes back at least 34 years - there was a paper by Pati and Salam entitled "Lepton Number as the Fourth Color" which tries to do exactly this. This is an extraordinarily famous paper - with 2790 citations, it is the 34th most cited paper in all of HEP, and the single most cited BSM phenomenological model. The arrogance of your claim is only overshadowed by its ignorance.

 

[quantumkiko]

I was surprised for you to say that my claim was "arrogant" and that my question denoted a "you guys are doing it all wrong" kind of tone, and further added that I many people would find my Question disrespectful. That was too much of an assumption over there. I just posed an honest question that needed an answer, not anything more than that.

I simply needed an answer to my question and I found it unpleasant to be criticized at any underlying tone or motive that you might have produced from my inquiry. Sorry but I didn't quite get the answer to my question. I was simply asking why and was just expecting an answer that might have come from a knowledgeable person that is as excited and fascinated in sharing what he/she knows to someone who is interested in knowing more about the subject.

There is nothing rude/disrespectful about someone asking a question because he doesn't know much about the subject. In the first place, this is how we pose questions, we don't know enough and we want to know more, even if the answer has already been existing for years. I may be wrong and you may be right, but with respect, you can put me closer and more fascinated with the truth, instead of putting down my interest in it.

 

[Haelfix]

Grand unified theories are defined as the unification of the strong force and the electroweak force (which is part of the standard model). It is expected to occur for a number of theoretical reasons.

There is a gigantic literature on the subject, and most of the best models were already written down some thirty years ago.

Unfortunately, there are very few experimental constraints that you can throw at the problem, and the ones that do exist are all famous (eg doublet triplet splitting problem, proton decay, astrophysics bounds, flavor changing neutral currents etc).

So you are left with tens of thousands of different possiblilities and not much to discriminate them with, other than mostly aesthetic criteria (simplicity, elegance, lack of finetuning, explanatory power, etc). All these models share a feature in common with the standard model, in that they are adhoc and not necessarily derived from something fundamental.

 

[Vanadium 50]

I was surprised for you to say that my claim was "arrogant" and that my question denoted a "you guys are doing it all wrong" kind of tone, and further added that I many people would find my Question disrespectful. That was too much of an assumption over there. I just posed an honest question that needed an answer, not anything more than that.

I don't buy that for an instant. While one could have asked an honest question - e.g. "What is the status of strong and electroweak unification", or "How come I read a lot about strings and loop quantum gravity but not a lot about strong and electroweak unification?" - but despite your denials, your original post certainly did take the position that the community was doing it wrong. Let me remind you of what was said:

I was wondering why physicists already bother on searching for a grand unified theory if they haven't even unified the electroweak with the strong force (electrostrong) yet.

"Why do they bother" is unquestionably a question with a tone of "they are doing it wrong". You could have said "why do they do it this way", which would have been non-judgmental, but "why do they bother" is judgmental, and indicates that the physics community has come short in your judgment.

Shouldn't we take things one step at a time?

Is this not criticism? Is the complaint not that the physics community is doing the wrong thing?

I don't like the idea that we are jumping this "gap" in search for one that unifies all the four forces already.

This is a statement. You don't like what you think is happening. Of course, as was pointed out, this statement is built on a foundation of ignorance. In my view, it would have been wiser to have found out if the statement were even true before your criticism.

So, aren't we assuming too much by making this jump?

Is this not criticism? Is the complaint not that the physics community is doing the wrong thing?

 

[arivero]

Grand unified theories are defined as the unification of the strong force and the electroweak force

Indeed. Most probably, the OP thought that GUT was a term to refer to theories including gravity. It does not help that most of the BeyondStandardModel topics are about theories including gravity.

When I was student, I got a kind of opposite mistake: to thing that a TOE was any Total theory of HEP, thus not referring to gravity. Let's say, this nomenclature is not easy to manage.

 

[arivero]

Let me add, I tend to agree that any BSM theory should first worry about HEP, and only in a second though to look at cosmo/gravity. In this way, it is not so mad to do string theory around Calabi-Yaus, for instance

 

[Vanadium 50]

Let me add, I tend to agree that any BSM theory should first worry about HEP, and only in a second though to look at cosmo/gravity.

While I tend to agree with that, I would also say that it's not crazy to keep gravity in the back of your mind when doing that. If you're deciding whether to pursue Model X or Model Y, if you know Model X will have anomalies when gravity is included, maybe Model Y would be a better starting point.