Has Theoretical Physics met a bit of a roadblock?

[Lunct]

I personally am undecided on the issue but it goes without saying that physicists have been stuck on the same problems for years. Sure they recently proved gravitational waves, but one could say that we knew they were they existed anyway with near certainty, if they weren' t there it would be a problem with general relativity. The thought was brought up recently in the latest episode of Big Bang Theory, in which one of the characters tears apart the university on public radio when he says that they have spent so much money and not found any solutions to the largest problems in theoretical physics. The biggest problems the show talk about were quantum gravity, supersymmetry and dark matter. Scientists have been stuck on those problems for decades.
Is this true? I would love the hear your insights.

 

[phyzguy]

I would agree with you. It's been known for a long time that quantum mechanics and GR are fundamentally inconsistent, but how to solve the inconsistency is where the issue is. I'm not sure this is a new phenomenon. You could argue that it was clear after Maxwell published his equations of EM in about 1865, that there was a clear inconsistency with Newtonian gravity, where changes propagate instantaneously. However, it wasn't until Einstein developed GR in 1915 that this inconsistency was resolved. Fundamental paradigm shifts can take a long time.

 

[Lunct]

I would agree with you. It's been known for a long time that quantum mechanics and GR are fundamentally inconsistent, but how to solve the inconsistency is where the issue is. I'm not sure this is a new phenomenon. You could argue that it was clear after Maxwell published his equations of EM in about 1865, that there was a clear inconsistency with Newtonian gravity, where changes propagate instantaneously. However, it wasn't until Einstein developed GR in 1915 that this inconsistency was resolved. Fundamental paradigm shifts can take a long time.

You're right, however, Einstein was the first person to really realize that inconsistency with Maxwell and Newton. It wasn't the whole of the world of physics working towards that problem.

 

[Borek]

Exactly this way of reasoning makes me think that we may be barking up the wrong tree. The longer there is no progress the more I think quantum gravity doesn't exist and gravity is an emergent effect (something like Verlinde's entropic gravity).

That's not because I understand the details, more like I compare the effort (about 100 years already) with the results (basically none) and it makes me think lack of progress can mean the solution doesn't exist.

 

[Lunct]

Exactly this way of reasoning makes me think that we may be barking up the wrong tree. The longer there is no progress the more I think quantum gravity doesn't exist and gravity is an emergent effect (something like Verlinde's entropic gravity).

That's not because I understand the details, more like I compare the effort (about 100 years already) with the results (basically none) and it makes me think lack of progress can mean the solution doesn't exist.

I really think the same about dark matter. It's scary because if we are looking at these problems the wrong way than our whole understanding of the universe could be wrong. We would have to completely rethink gravity if we cannot find dark matter.

 

[phyzguy]

I really think the same about dark matter. It's scary because if we are looking at these problems the wrong way than our whole understanding of the universe could be wrong. We would have to completely rethink gravity if we cannot find dark matter.

I don't agree with you on this. In my mind we have already "found" dark matter. We see it's gravitational interactions everywhere in many different types of astrophysical measurements. What if dark matter were a type of particle that only interacts gravitationally and has no other interaction, or has non-gravitational interactions so weak that it will never be feasible to see it in the lab? Then it would be impossible to "find" it any more than we already have. That wouldn't mean we need to re-think everything.

 

[Lunct]

I don't agree with you on this. In my mind we have already "found" dark matter. We see it's gravitational interactions everywhere in many different types of astrophysical measurements. What if dark matter were a type of particle that only interacts gravitationally and has no other interaction, or has non-gravitational interactions so weak that it will never be feasible to see it in the lab? Then it would be impossible to "find" it any more than we already have. That wouldn't mean we need to re-think everything.

You're right. I have never really looked at it that way.

 

[ZapperZ]

The thought was brought up recently in the latest episode of Big Bang Theory, in which one of the characters tears apart the university on public radio when he says that they have spent so much money and not found any solutions to the largest problems in theoretical physics. The biggest problems the show talk about were quantum gravity, supersymmetry and dark matter. Scientists have been stuck on those problems for decades.
Is this true? I would love the hear your insights.

This is utterly silly. The medical profession has been working for decades trying to cure cancer, ALS, the common cold, etc...etc. Yet, no one seems to complain that we have been spending "...so much money and no found any solutions...".

These are not problems that can be solved within a given deadline! In fact, I would say that progress is made gradually. The unrealistic expectation that we would stumble upon the magic solution one day is only a scenario that happens in the movies and, yes, TV shows!

BTW, many theorists in condensed matter physics and other areas neglected here will take exception of the short-sighted categorization of "theoretical physics" done here. It is perpetuating the misconception that this is ALL there is in "theoretical physics".

Zz.

 

[Borek]

It's scary because if we are looking at these problems the wrong way than our whole understanding of the universe could be wrong. We would have to completely rethink gravity if we cannot find dark matter.

I see nothing scary about that. Actually, to witness such a thing would be incredibly fantastic.

Not that I hold my breath.

 

[Lunct]

BTW, many theorists in condensed matter physics and other areas neglected here will take exception of the short-sighted categorization of "theoretical physics" done here. It is perpetuating the misconception that this is ALL there is in "theoretical physics".

Zz.

I believe that the problems in theoretical physics mentioned here are not all the problems, but the most significant.

 

[ZapperZ]

I believe that the problems in theoretical physics mentioned here are not all the problems, but the most significant.

No, they are not.

The "problems" that you mentioned here are part of the standard and common misconception and view of what many think as "theoretical physics". We see this often in this forum where students claim they want to do "theoretical physics" and they mean "... quantum gravity, supersymmetry and dark matter... ", because THOSE are the ONLY thing they see as being theoretical physics. Your TV show helps perpetuate that misconception while ignoring the fact that these areas comprise of a SMALL percentage of practicing physicists.

Zz.

 

[Lunct]

No, they are not.

The "problems" that you mentioned here are part of the standard and common misconception and view of what many think as "theoretical physics". We see this often in this forum where students claim they want to do "theoretical physics" and they mean "... quantum gravity, supersymmetry and dark matter... ", because THOSE are the ONLY thing they see as being theoretical physics. Your TV show helps perpetuate that misconception while ignoring the fact that these areas comprise of a SMALL percentage of practicing physicists.

Zz.

In that case can you please link me to some information on the rest of theoretical physics then.

 

[ZapperZ]

In that case can you please link me to some information on the rest of theoretical physics then.

Look at the various Divisions under the APS. Practically every single division, i.e. broad area of studies, has theory component to the subject.

Condensed matter theorists, for example, have won many Nobel Prizes (eg: Phil Anderson, Bob Laughlin,... etc.). In fact, the only person to have ever won the Physics Nobel prize TWICE is John Bardeen, a condensed matter theorist! It is also an established fact that the work done by Phil Anderson led to the the Higgs mechanism. So that field as as "fundamental" as anything out there.

Zz.

 

[Lunct]

Look at the various Divisions under the APS. Practically every single division, i.e. broad area of studies, has theory component to the subject.

Condensed matter theorists, for example, have won many Nobel Prizes (eg: Phil Anderson, Bob Laughlin,... etc.). In fact, the only person to have ever won the Physics Nobel prize TWICE is John Bardeen, a condensed matter theorist! It is also an established fact that the work done by Phil Anderson led to the the Higgs mechanism. So that field as as "fundamental" as anything out there.

Zz.

I tell you what, I am going to go to my town library (it is very big) and find the biggest book on condensed matter I can find.

 

[ZapperZ]

I tell you what, I am going to go to my town library (it is very big) and find the biggest book on condensed matter I can find.

Er... good luck!

Zz.

 

[ISamson]

I tell you what, I am going to go to my town library (it is very big) and find the biggest book on condensed matter I can find.

Why? You have Google!

 

[Borek]

Why? You have Google!

Google university teaches a mixture of separate facts, some of them wrong, some unrelated, some irrelevant. Good textbook contains a systematic approach that leaves no holes in your understanding of the subject. Don't even compare these things.

 

[Vanadium 50]

Lunct, since you are criticizing others for their lack of accomplishments, perhaps you should describe your own. Just for perspective, you know.

Second, you might look to see how far back you need to go to get to a Nobel prizewinner for theoretical work. Hint: it's measured in days. The one before that? 2016, Then you have to go all the way back to 2013. Then there's a huge dry spell all the way back to 2008. Now, you can pooh pooh this as not significant, but then I refer you to point #1.

Finally, Zz is 100% right. Most of physics being done is condensed matter. There's a huge amount of theoretical work being done there.

 

[Lunct]

Why? You have Google!

I prefer to read a book rather than read on Google because there are too many distractions on the internet. I know it sounds weird but I retain more information from books than from websites because on the internet I always end up clicking on links upon links, then checking my twitter. I often resort back to the internet if I am unable to find the correct information from books, and after I have read about science I always cross check it with internet information.

 

[Gigaz]

According to the daily upload on arxiv condensed matter is the largest subsection of contemporary physics. There are no books on "condensed matter". There are books on semiconductors, metals, perovskites, graphene, topological insulators, and so on.

 

[Lunct]

Lunct, since you are criticizing others for their lack of accomplishments, perhaps you should describe your own. Just for perspective, you know.

Second, you might look to see how far back you need to go to get to a Nobel prizewinner for theoretical work. Hint: it's measured in days. The one before that? 2016, Then you have to go all the way back to 2013. Then there's a huge dry spell all the way back to 2008. Now, you can pooh pooh this as not significant, but then I refer you to point #1.

Finally, Zz is 100% right. Most of physics being done is condensed matter. There's a huge amount of theoretical work being done there.

Criticising others? I wrote specifically wrote that I do not agree or disagree with the whole theoretical physics road block thing. I just wanted to see what other people thought on the issue ergo I never thought theoretical physicist are rubbish, did I?

I personally am undecided

Look I wrote that on the top of the post.
To be honest, I disagreed with it more than agreed with it, however, I wanted to remain open-minded as it was the first time I had really thought about that issue.

 

[Lunct]

According to the daily upload on arxiv condensed matter is the largest subsection of contemporary physics. There are no books on "condensed matter". There are books on semiconductors, metals, perovskites, graphene, topological insulators, and so on.

I will I I will look for those books. Thank you.

 

[ISamson]

I prefer to read a book rather than read on Google because there are too many distractions on the internet. I know it sounds weird but I retain more information from books than from websites because on the internet I always end up clicking on links upon links, then checking my twitter. I often resort back to the internet if I am unable to find the correct information from books, and after I have read about science I always cross check it with internet information.

Yes, I totally agree.

 

[Jonathan Scott]

There's a lot of discovery going on in many areas of theoretical physics, so I don't believe there is a "roadblock" overall.

What concerns me are the cases where we seem to have accepted theory which directly conflicts with other accepted theory or with current experiment. This includes for example the well-known incompatibilities between GR and QM including GR's prediction of physically meaningless singularities within black holes. There is also the fact that in order for GR to be compatible with experimental observations on the scale of galaxies or above it is necessary to assume invisible "dark matter" whose distribution within galaxies curiously gives the same effect as mathematically trivial (but physically extremely implausible) modified gravity theories based only on the visible matter.

I'd agree there's a bit of a roadblock on the mainline in such cases, and a breakthrough is needed.

 

[Lunct]

There's a lot of discovery going on in many areas of theoretical physics, so I don't believe there is a "roadblock" overall.

What concerns me are the cases where we seem to have accepted theory which directly conflicts with other accepted theory or with current experiment. This includes for example the well-known incompatibilities between GR and QM including GR's prediction of physically meaningless singularities within black holes. There is also the fact that in order for GR to be compatible with experimental observations on the scale of galaxies or above it is necessary to assume invisible "dark matter" whose distribution within galaxies curiously gives the same effect as mathematically trivial (but physically extremely implausible) modified gravity theories based only on the visible matter.

I'd agree there's a bit of a roadblock on the mainline in such cases, and a breakthrough is needed.

Thank you for your insight. :)

 

[ZapperZ]

What concerns me are the cases where we seem to have accepted theory which directly conflicts with other accepted theory or with current experiment. This includes for example the well-known incompatibilities between GR and QM including GR's prediction of physically meaningless singularities within black holes.

But what do you mean by "... we seem to have accepted theory..."? If the so-called incompatibilities between GR and QM have been "accepted", why are we STILL doing plenty of research on it? This is not the sign of accepting anything.

The FACT (and it is a fact!) that they each WORK, and work very well in their respective domain means that there is a high degree of validity with them. This is no different than using classical mechanics to build the house that you live in. You just don't throw out Newtonian mechanics just because it has been superseded by other more complete theories.

Unless, of course, you too are equally concerned that we have "accepted" Newtonian theory when it is "incompatible" with SR and QM in the domains where it doesn't belong.

Zz.

 

[Lunct]

But what do you mean by "... we seem to have accepted theory..."? If the so-called incompatibilities between GR and QM have been "accepted", why are we STILL doing plenty of research on it? This is not the sign of accepting anything.

The FACT (and it is a fact!) that they each WORK, and work very well in their respective domain means that there is a high degree of validity with them. This is no different than using classical mechanics to build the house that you live in. You just don't throw out Newtonian mechanics just because it has been superseded by other more complete theories.

Unless, of course, you too are equally concerned that we have "accepted" Newtonian theory when it is "incompatible" with SR and QM in the domains where it doesn't belong.

Zz.

Imagine building a house using relativity and quantum mechanics maths. Oh God.

 

[Jonathan Scott]

But what do you mean by "... we seem to have accepted theory..."? If the so-called incompatibilities between GR and QM have been "accepted", why are we STILL doing plenty of research on it? This is not the sign of accepting anything.

I didn't say the incompatibilities have been "accepted". GR and QM have been separately "accepted" to a level which includes well-known incompatibilities with one another.
And yes, there is interesting research going on; I'm eagerly awaiting the LIGO binary neutron star results, as those will push GR further than any previous test.

 

[ZapperZ]

I didn't say the incompatibilities have been "accepted". GR and QM have been separately "accepted" to a level which includes well-known incompatibilities with one another.

But that is what I am arguing about. GR and QM have been separately accepted because THEY WORK within their respective domain! You are basically complaining that we are using our iPhones, GPS, etc.! So yeah, we HAVE accepted QM and GR!

The "incompatibilities" that you cited are predominantly ON PAPER. And I hate to tell you this, but in physics, there are MANY research-front areas that are incompatible with a number of theories. Look at high-Tc superconductivity, which is still looking for an accepted theory. Many of these are thought to be incompatible with the amazingly successful BCS theory. Yet, we have used BCS theory (still using it today) and have even given it the Nobel Prize!

Zz.

 

[Lunct]

Yes, I totally agree.

So much for not getting distracted in the library. I went there with the intent to find books about topics in condensed matter but did not leave with that. I got distracted on a book about this exact discussion we are having.

 

[Jonathan Scott]

But that is what I am arguing about. GR and QM have been separately accepted because THEY WORK within their respective domain! You are basically complaining that we are using our iPhones, GPS, etc.! So yeah, we HAVE accepted QM and GR!

It's fine accepting them within their established scope of validity.

GR is known to be incredibly precisely accurate in weak fields at the scale of the solar system and quite a long way beyond that (including the creation and propagation of gravitational waves), but that's basically just a small relativistic correction to Newtonian theory. It's also known to be fairly accurate in stronger fields, but as we move through neutron stars towards collapse the results become more qualitative than quantitative, and so far we have no direct confirmation of the existence of event horizons, nor of other related predictions such as black holes being unable to retain any significant magnetic field.

What concerns me is that the theoretical predictions of GR beyond that strength and scale diverge from the current experimental observations and come into conflict with QM, but the fact that it works so well in the solar system is often assumed to mean that it is valid at all scales, so we end up for example with "dark matter" being assumed, and with predictions of physically meaningless singularities.

When the first LIGO GW (gravitational wave) observation occurred, the Fermi observatory reported an apparent GRB (gamma ray burst) at the same time, which appeared to be statistically significant, although not totally convincing. To someone who is open to GR only being an approximation, this suggests the very interesting possibility that objects of that mass don't actually have an event horizon, so the collision could emit electromagnetic radiation. However, the general reaction was that GR says no significant electromagnetic radiation can be produced by a collision of black holes, so it must be a mistake or require an exotic explanation (such as a collision inside a star). The theory, pushed well beyond its previously tested scope, was immediately assumed to take precedence over experiment. Some re-analysis concluded that the probability of the Fermi observation being a false signal in background noise was actually higher than originally calculated (although still small), and no other observatories detected anything, so the result was apparently comfortably dismissed. This may well have been the correct conclusion, but I was quite disturbed by the way in which the result was apparently immediately assumed by the "establishment" to be wrong based on theory which had never before been tested near that limit.

This suggests to me that although GR is an attractively neat theory with a wide range of successful applicability, it is probably being accepted more strongly outside that range than the evidence warrants, which could make it more difficult than necessary to make progress in finding the next better theory. Athough I know this isn't preventing some people from trying, I still consider it a "bit of a roadblock".

 

[e-pie]

I agree with @Vanadium 50

One thing I can say that it is not the right time for the OP to question whether theoretical physics has hit a roadblock or not. We have a great many scientists having immense expertise on the subject that won't match the level of someone whose age is only 14.

I would advise to achive academic accomplishments(maybe passing with good grades or having indepth knowledge of physics)first and then question the success of ongoing research on physics.

Not to discourage you from posting but this sort of question is really not suited for your age.

These are some of the ongoing research on theoretical physics. Of course these are not the holy grail of Physics like Grand Unification etc but these are Significant contributions to the development of the subject.
I cannot link any research paper because I am not a Physicist but that will not stop me from defending years of hardwork of Physicists. I think @ZapperZ has a list of recent noteworthy physics papers

https://www.nature.com/subjects/theoretical-physics
https://physics.wustl.edu/research
http://insti.physics.sunysb.edu/~siegel/the.html
http://ctp.lns.mit.edu/research.html