Talk:String theory

Why must everything be particle-based?

I don't understand any of the mathematics behind string theory, so I don't know the situation. So from my point of view, I don't get why people are trying to assign gravity to its own particle. Why can't gravity just be the curvature of spacetime around massive objects, and leave it at that? Particles follow spacetime. Said spacetime is being curved because of a massive object. Why must gravity be assigned its own particle? And, if it is, what is it doing with those particles to cause you to fall? Is it throwing them at you? I mean, I know any classical way I try to think of particles will be dead wrong, so probably not. But you get the point. I don't understand why people need the graviton there is an other concept called cosmic essence concept which includes sayoing there is no one dimension but there is a unknown undfineable existing matrix which makes up the one dimensional string. Tickbeat (talk) 15:28, 17 April 2024 (UTC)

Wave–particle duality. The problem is that general relativity is not cosistent with quantum mechanics. This is why most physicists believe that a quantum theory of gravity is needed. –LaundryPizza03 (dc̄) 21:44, 20 April 2024 (UTC)

These are the words I hear all the time, and they provide next to no information on why we need the graviton. If you either don't know the technical details of why, or you don't think I can handle it, then I guess just read it and move on :P Tickbeat (talk) 23:57, 26 April 2024 (UTC)

In that case, I had to do a little research and came across this article about such a theory and the technical problems encountered in combining quantum mechanics with classical gravity without invoking a graviton. [1] –LaundryPizza03 (dc̄) 15:17, 27 April 2024 (UTC)

I have always found it intriguing (and somewhat irritating) that quantum mechanics was developed as a particle (excitation) and force (field) theory, while Einstein et al. used a space-time approach to explain gravity alone. Could the three other forces (electromagnetism, weak and strong forces) be explained by space-time properties? 38.134.123.209 (talk) 18:03, 11 September 2024 (UTC)

String is not a dictionary; it has single language. We can separate it on life code, and frozen code to prove. 62.181.56.1 (talk) 10:08, 2 January 2025 (UTC)

No, not by spacetime, but they can be described geometrically too; instead of the curvature of spacetime, it’d be the curvature of gauge fields. All four forces can be described this way, but things still fail when you have to deal with how quantum mechanics works near/inside black holes. OverzealousAutocorrect (talk) 22:41, 10 January 2025 (UTC)

@LaundryPizza03 97.85.68.104 (talk) 00:45, 29 October 2025 (UTC)

I can't figure out what you're pinging about. –LaundryPizza03 (dc̄) 01:01, 29 October 2025 (UTC)

a string will look just like an ordinary particle

This unsourced claim is of course nonsense on several levels. What is an "ordinary particle"? What do particles "look like"? The overwhelming evidence in QM is that no local realism model is correct: particles are an effect that appears during interaction, not a cause. Even simpler, to "look" means to respond to light in a way that can visually perceived, which does not happen. Since the stringiness aspects are a level tinier, this phrase is even sillier.

Unfortunately fixing these kinds of statements is difficult because the mathematical concept of particles is central to models of QM. So presumably strings as the wiggly thing. It is difficult to explain in a sentence or two how particles can be both critical to models and not a concept of reality. Johnjbarton (talk) 18:12, 6 January 2025 (UTC)

You are missing the key start of that sentence "On distance scales larger than the string scale..." It actually makes decent sense, especially for the usage of a simple overview which is aimed at a lay audience; if you zoom out, a closed string does indeed look like (not physically via photons, but in the other sense of the word of behaving as) a point, and does behave as such, hence what the sentence seems to convey. More technically, the low energy effective field theory of string theory is a quantum field theory whose excitations are particles (which are just strings that have been zoomed out of), which is what the sentence is conveying, and accurately so.

Not sure what you mean by "particles are an effect that appears during interaction"; particles are by definition unitary irreducible representations of the Poincare group, see Wigner's classification. This makes no reference to interactions and holds in free field theories.

OpenScience709 (talk) 00:08, 7 January 2025 (UTC)

You're ignoring my first complaints: what do ordinary particles look like? Physically, assuming that particles zoom around in QM gives incorrect predictions (delayed choice, Bell's theorem). Falling back on this language for a lay audience is not correct and sets up endless rounds of "paradox" questions.

"behaving as" is perfectly reasonable, so: "at larger distances scales a string behaves like a particle" is fine.

What do "excitations" look like? As far as I am aware, QFT avoids "looks like" altogether. Paul Teller has a nice little book which basically concludes that QFT does not support anything like particles in the classical sense.

Wigner's classification is mathematics, but this sentence is clearly physics ("look"). (This is the distinction that is so vexing for describing this stuff. So in QM we have equations with positions of negative charges but then we will later say, oh those aren't electrons.) Johnjbarton (talk) 01:03, 7 January 2025 (UTC)

Again, "look like" has two meanings as a phrase, one of which is identical to "behaving as", which is contextually clear that that's the use. If you CTRL+F a physics textbook you'll find plenty of "look", "looks like", and absolutely no one is confused about whether that is referring to physically interacting with photons. But if you want to change it, go for it.

I really don't quite know what your aim is here. Particles are a well defined concept in QFT; they are unitary irreps of the Poincare group. That's what we mean by particles. Excitations of the quantum field are exactly these objects. The different types of particles are classified by Wigners theorem (hence why I brought it up). Just cause its a mathematical statement doesnt mean its not a physical statement as well...

I don't know to what extent your Teller reference is relying on the "in the classical sense". I mean yeah, you don't have a bunch of balls hitting each other, but we still have the concept of particles by the aforementioned definition which is what physicists mean by a particle in QFT. Additionally, the low energy limit of QFT also just becomes a classical field theory where the particles do indeed behave classically. The low energy limit of two electrons scattering calculated in QED just becomes identical to having two point particles scatter in classical electrodynamics. OpenScience709 (talk) 10:57, 7 January 2025 (UTC)

Particles in physics are a mathematical construct, a mental invention aiding the construction of models which predict natural phenomena. Physicists understand that visualizing these constructs is useful up to a limit and they are trained to avoid equating math with "reality". In presenting physics we have to avoid presenting the visualization aids as an actual model of the phenomenon.

Your definition of particles is completely at odds with the normal lay point of view. That is what I am trying to get across. When we write "ordinary particle", a lay audience is entitled to assume that we mean a tiny sphere, a BB.

Maybe most readers of this article are experienced readers of physics, IDK. Anyway I made a change. Johnjbarton (talk) 15:41, 7 January 2025 (UTC)

Examples of Realistic Physics could be added to Particle Physics Section?

Under phenomenology -> particle physics there's this statement:

"Such compactifications offer many ways of extracting realistic physics from string theory."

But as far as i can see there arent examples of realistic (particle) physics listed in this subsection. I think it would be very useful to readers if for example the sentence was changed to something like:

"Such compactifications offer many ways of extracting realistic physics from string theory (e.g. a, b, c, etc)"

However I don't know enough about string theory myself to be able to make this change. Perhaps someone can help out?

Of course, my suggestion might not be very good, and I am open to the idea that its fine as is (e.g. maybe the realistic predictions would require a large amount of new text / be quite involved to explain) BennBluee (talk) 22:16, 27 April 2025 (UTC)

I think we should just delete the two related sentences as unsourced. Absent sources we have no practical to take the path you propose. Johnjbarton (talk) 02:56, 28 April 2025 (UTC)

I have now provided a source. OpenScience709 (talk) 07:19, 28 April 2025 (UTC)

Feynman diagrams don’t depict the paths on point-like particles.

”perturbative quantum field theory uses special diagrams called Feynman diagrams to organize computations. One imagines that these diagrams depict the paths of point-like particles and their interactions.”

This statement found in this page is false. One of the first things that students learn in their first introductory course in quantum field theory is to resist the temptation to interpret Feynman diagrams as depictions of the paths of particles in space / worldlines in spacetime. It needs to be removed / amended. See, for example, this discussion and countless others on stackexchange and standard physics textbooks Siupa (talk) 12:38, 8 September 2025 (UTC)

You need a more reliable source for this claim, and it belongs first at Feynman diagram, not here. –LaundryPizza03 (dc̄) 06:02, 9 September 2025 (UTC)

I mean, if the statement is false and its being made in this article, then it is a discussion that does belong here... As for the matter at hand, it is technically false yes, although it is sometimes a useful fiction. Feynman diagrams are merely calculational tools rather than literal paths of particles; a good way to view it is from the path integral perspective where the physics is a weighted sum of all possible paths. Likewise the actual process is a weighted sum of all possible diagrams which also in a way represent the paths so its really the same thing, as it should be.

Hence, the statement should be amended to for example "perturbative quantum field theory uses special diagrams called Feynman diagrams to organize computations. These can to be viewed as describing paths of point-like particles and their interactions, although the actual physical process is a sum of all Feynman diagrams and so the diagrams themelves do not literally depict how the particles behave." Or something more eloquent. OpenScience709 (talk) 09:24, 9 September 2025 (UTC)

Wiki Education assignment: Organic Chemistry I

This article is currently the subject of a Wiki Education Foundation-supported course assignment, between 3 September 2025 and 19 December 2025. Further details are available on the course page. Student editor(s): Hhebah 13 (article contribs). Peer reviewers: Rboyer24.

— Assignment last updated by Rboyer24 (talk) 03:31, 14 October 2025 (UTC)

String theory is not an Organic Chemistry topic... and certainly doesnt fall into the category of introductions to "fundamental principles of organic chemistry"... OpenScience709 (talk) 08:59, 18 September 2025 (UTC)

What's happened since the '00s?

There is a quarter-century-wide chasm in the "History" section. Surely something worthy of mention has happened this millennium. 2603:8001:D300:342F:2B12:48A4:6D17:5FB5 (talk) 00:17, 24 October 2025 (UTC)

I'll tell you what happened: the coupling of the three forces did not go as planned.

So, yes, string theory is falsifiable, and that actually happened. tgeorgescu (talk) 01:09, 24 October 2025 (UTC)

Plenty of stuff happened. Continual work in holography, attempts at construction of dS vacua (KKLT, LVS), swampland program, etc, along with other stuff in other parts of string theory research I know far less about. Someone just has to sit down and write the update. OpenScience709 (talk) 09:46, 24 October 2025 (UTC)

For what I mean see Lincoln, Don (2009). The Quantum Frontier: The Large Hadron Collider. JHU Press. p. 41. ISBN 978-0-8018-9644-6. Retrieved 26 October 2025.

But this paper denies that SUSY has been debunked: Constantin, L.; Kraml, S.; Mahmoudi, F. (2025). "The LHC has ruled out supersymmetry – really?". Nuclear Physics B. 1018: 117012. doi:10.1016/j.nuclphysb.2025.117012.{{cite journal}}: CS1 maint: article number as page number (link) tgeorgescu (talk) 23:43, 26 October 2025 (UTC)

Supersymmetry has obviously not been ruled out (and string theory definitely hasn't). Only low scale supersymmetry (at scales accessable to the LHC). There is nothing ruling it out at higher energies. OpenScience709 (talk) 11:35, 27 October 2025 (UTC)