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String theory can now describe a universe that has dark energy?
- mono442 9mo agoOnly in universe with 5 dimensions. Shouldn't string theory be given up on at this point? This theory has existed for over 50 years and hasn't produced any results. Even the predictions made by it such as e.g. supersymmetry have not been confirmed despite searching for them at particle colliders.
- boxed 9mo agoIt has produced some good math though. That's something.
- isolli 9mo agoAt what opportunity cost?
- kakacik 9mo agoIf you want to bash badly-spent potential look at people doing cutting edge ad research and optimization, or HFT. This is at least good base research that others can build on.
- isolli 9mo agoFair point, but waste in one domain should not be used to excuse waste elsewhere. Unless your argument is that it's generally hard for human societies to know where to best invest their scientific talent without the benefit of hindsight.
- hahahahhaah 9mo agoI agree plus ST takes a person who would have researched somewhere else. The Googler or Jane Street or guy who decides to travel the world in the canoe have different reasons and probably would need way more persuading to be in academia.
- lacunary 9mo agohuman societies don't decide where to invest their talent; individuals do
- defrost 9mo agoThink of it as a playground for the exercise and training of a pool of minds that will one day either make the glove fit or kick the sand castle over replacing it with a better mousetrap. Too many metaphors? Hmmm, maybe fold in some dimensional reduction somehow.
- bluGill 9mo agoString theory has generated a lot of hype over the years, but never delivered anything. Looks to me like they are all the negatives you hate about ad research.
- computerfriend 9mo agoAdvertising has been a net negative and the mathematics produced by string theory research is amazing.
- azan_ 9mo agoBut HFT is good! It allows better pricing of equities and increases liquidity.
- tomrod 9mo agoLow. It's too expensive to send all of humanity across the stars at present.
- boxed 9mo ago100% unknown. That's always the problem with science and why political control and direction always backfires and is stupid.
- n4r9 9mo agoAs I understand it, it's still our best candidate for a unified theory of everything. Not for lack of effort in researching alternatives, either.
- aurareturn 9mo agoShouldn't string theory be given up on at this point? Has anti string theory propaganda taken over HN? Sabine Hossenfelder succeeded? Anyone who is anti string theory actually qualified to make statements saying string theory is wrong or not worth more investment from researchers? Are these anti string theory posts on HN mostly just laymen hearing how string theory can’t be tested and we wasted a lot of resources on it so it needs to be repeated on every string theory post here?
- squeefers 9mo agoSusskind himself said its dead in the water. We dont live in an anti de-Sitter space, the basis of string theory.
- aurareturn 9mo agoSource?
- simiones 9mo agoHere is a lengthy interview where he discusses this at length (with a timestamp where he says exactly that String Theory, the precise mathematical model, doesn't describe the real world): https://www.youtube.com/watch?v=2p_Hlm6aCok&t=10m15s https://www.youtube.com/watch?v=2p_Hlm6aCok&t=10m15s This also references this podcast discussion between Leonard Susskind and Lawrence Krauss, where they discuss the same thing: https://www.youtube.com/watch?v=qhszd_wqAgQ https://www.youtube.com/watch?v=qhszd_wqAgQ Note that he still thinks that there is a way to produce some kind of similar theory, "a string theory" as opposed to "String Theory", could be the best answer.
- aurareturn 9mo agohttps://www.reddit.com/r/AskPhysics/comments/1kolwxm/last_year_leonard_susskind_said_he_is_100_sure/ https://www.reddit.com/r/AskPhysics/comments/1kolwxm/last_ye... According to this Reddit thread, he doesn't say it's "dead in the water" at all. It's just a version of string theory. This is what I'm afraid of. People who aren't qualified spreading fake news on string theory. I don't claim to be qualified. I just want to call out HN people who are extremely confident that string theory is dead but has no background in physics.
- deleted 9mo ago[deleted]
- yyyk 9mo agoThe issue isn't string theory yes or no (there are reasons physicists went this way and other alternatives aren't so much better), but the difficulty in getting data and testable predictions. It's very likely the most effective way to help particle physics is getting way more data at high energies, not a new theory.
- barishnamazov 9mo agoI foolishly sat in 8.821 [0] while at MIT thinking I could make sense out of quantum gravity. Most of the math went over my head, but the way I understand this paper, it’s basically a cosmic engineering fix for a geometry problem. Please correct me if necessary. String theory usually prefers universes that want to crunch inwards (Anti-de Sitter space). Our universe, however, is accelerating outwards (Dark Energy). To fix this, the authors are essentially creating a force balance. They have magnetic flux pushing the universe's extra dimensions outward (like inflating a tire), and they use the Casimir effect (quantum vacuum pressure) to pull them back inward. When you balance those two opposing pressures, you get a stable system with a tiny bit of leftover energy. That "leftover" is the Dark Energy we observe. You start with 11 dimensions (M-theory) and roll up 6 of them to get this 5D model. It sounds abstract, but for my engineer brain, it's helpful to think of that extra 5th dimension not as a "place" you can visit, but as a hidden control loop. The forces fighting it out inside that 5th dimension are what generate the energy potential we perceive as Dark Energy in our 4D world. The authors stop at 5D here, but getting that control loop stable is the hardest part The big observatiom here is that this balance isn't static -- it suggests Dark Energy gets weaker over time ("quintessence"). If the recent DESI data holds up, this specific string theory solution might actually fit the observational curve better than the standard model. [0] https://ocw.mit.edu/courses/8-821-string-theory-and-holographic-duality-fall-2014/ https://ocw.mit.edu/courses/8-821-string-theory-and-holograp...
- simiones 9mo ago> we perceive as Dark Energy in our 4D world This is a bit of a technicality, but we don't live in a 4D world, we live in a 3+1D world - the 3 spacial dimensions are interchangeable, but the 1 time-related dimension is not interchangeable with the other three (the metric is not commutative). I'm bringing this up because a lot of people seem to think that time and space are completely unified in modern physics, and this is very much not the case.
- pwatsonwailes 9mo agoTo expand on this a little for those interested, time has properties space doesn't. For example, you can turn left to swap your forward direction for sideways in space. You cannot turn though, in a way that swaps your forward (as it were) direction in space for a backward direction in time. Equally, cause always precedes effect. If time were exactly like space, you could bypass a cause to get to an effect, which would break the fundamental laws of physics as we know them. There's obviously a lot more, but that's a couple of examples to hopefully help someone.
- isolli 9mo agoHm, string theory can describe a lot of things, but it's not testable with current technology. I'm pretty sure that other mathematical constructs exist that could also describe a similar set of properties, but we just happened to stumble upon string theory first, and got enamored with some of the nice properties it had initially.
- pseingatl 9mo agoThey had to keep the theory alive somehow.
- amelius 9mo agoSounds like overfitting.
- PlatoIsADisease 9mo agoYeah I am awaiting the Copernican Revolution of quantum mechanics before I care about this stuff. I personally have no practical application, so it does me no good to learn this stuff that will be obsolete sooner or later.
- forgotpwd16 9mo agoJust few extra dimensions and you can handle anything.
- yyyk 9mo agoThe prediction is just 105 orders of magnitude (and an extra dimension) away, but ok.
- jl6 9mo agoOnly about 2 orders of orders of magnitude - not bad for string theory.
- isolli 9mo agoI don't know who wrote the title for this submission, but adding a question mark that is not in the linked article seems like a terrible editorial decision.
- mellosouls 9mo agoAgree, its editorialising and not allowed under the guidelines here (unless it was in the original and that was changed), but given the uselessness of the field you could argue that any "String Theory" claim in any title should have an automatic question mark (or perhaps several) attached afterwards.
- Gualdrapo 9mo ago> given the uselessness of the field It's not useless, though. String theory can be a fad (or "difficult to prove", per Witten) but some of the mathematics used in its research or "trying to prove it" have been used in other fields.
- hahahahhaah 9mo agoYes. Like Python can describe any turing machine.
- smnplk 9mo agoHere is the latest and in my opinion the best interview with Ed Witten [1] Things he talks about go mostly over my head. What disappointed me a little bit is that he seems to be a materialist. But that is pretty common position among physicists anyway, so not that surprising. [1] - https://www.youtube.com/watch?v=sAbP0magTVY https://www.youtube.com/watch?v=sAbP0magTVY
- DonHopkins 9mo agoIf materialists disappoint you, then you should check out Deepak Chopra, for all your self affirming quantum woo needs and desires. He will make your dreams come true! Just buy lots of his books, and you both will be very happy.
- smnplk 9mo agoYou are clearly very philosophically inclined.
- exe34 9mo agoI'm sad to discover that wisdomofchopra is no more.
- aeve890 9mo agoWe have llms now so no need for another bullshit generator.
- DonHopkins 9mo agoRobots will need to become fat and human before they can ever generate Deepak Chopra Quality Woo! https://www.youtube.com/watch?v=aO2dPIdEaR4 https://www.youtube.com/watch?v=aO2dPIdEaR4 "But as Deepak Chopra taught us, quantum physics means anything can happen at any time for no reason. Also, eat plenty of oatmeal, and animals never had a war! Who's the real animals?" -Professor Hubert Farnsworth
- exe34 9mo ago
- aurareturn 9mo agoSide note, there’s been a few recent publications showing that dark energy may not be needed to explain what we are seeing. 1. Inhomogeneity backreaction (Moffat 2025) Large-scale cosmic inhomogeneities such as voids and dense regions can create an effective expansion history that mimics evolving dark energy when averaged using standard homogeneous assumptions. https://arxiv.org/abs/2503.20912 https://arxiv.org/abs/2503.20912 2. Timescape cosmology (Wiltshire) Because cosmic voids expand faster than dense regions and dominate volume at late times, observers may infer acceleration from redshift data even if the universe is not globally accelerating. https://www.livescience.com/physics-mathematics/dark-energy/cosmic-voids-may-explain-the-universes-acceleration-without-dark-energy https://www.livescience.com/physics-mathematics/dark-energy/... 3. Local giant void hypothesis If the Milky Way resides inside a large underdense region, locally measured redshifts and distances can bias expansion measurements and partially explain apparent acceleration and Hubble tension. https://www.livescience.com/space/cosmology/echoes-from-the-big-bang-suggest-earth-is-trapped-inside-a-giant-cosmic-void-scientists-claim https://www.livescience.com/space/cosmology/echoes-from-the-... 4. Void universe models (LTB cosmologies) Placing the observer near the center of a large cosmic void can reproduce supernova redshift–distance relations without dark energy, though such models struggle with other cosmological constraints. https://arxiv.org/abs/0807.1443 https://arxiv.org/abs/0807.1443 5. Structure formation and virialisation effects The growth of cosmic structure and entropy production alters averaged expansion rates, potentially generating an apparent dark-energy-like signal without introducing a new energy component. https://www.aanda.org/articles/aa/full_html/2024/09/aa50818-24/aa50818-24.html https://www.aanda.org/articles/aa/full_html/2024/09/aa50818-... 6. Redshift drift as a discriminator Measuring how cosmological redshifts change over time can distinguish true cosmic acceleration from redshift effects caused by voids or inhomogeneous expansion. https://arxiv.org/abs/1010.0091 https://arxiv.org/abs/1010.0091
- squeefers 9mo agoString theory does not work with de-Sitter spaces, only with anti de-Sitter spaces. Science has proved we are living in a de-Sitter space. String theory cannot be true.
- dmd 9mo agoThat is literally what this article is about.
- squeefers 9mo ago> “What they have found is a 5D de Sitter solution, and we don’t live in 5D,” said > Antonio Padilla(opens a new tab) of the University of Nottingham. > Still, the work is expected to launch a new era in matching the mathematical > elegance of string theory to the actual world we live in." yeah, sounds real promising. string theory all over. nice maths but who cares if it doesnt map to reality, its nice maths!
- bluGill 9mo agoWhich would be fine if they were calling themselves mathematicians, we can debate if their ideas are more/less worthy of funding vs all the other mathematicians working on interesting math that might or might not be useful. However when they call themselves physicists we demand they prove they are creating useful physics. There are other areas of study in Physics that are producing results and thus seem more worthy of funding. Remember resources are limited. We cannot fund everyone who wants it. Society needs to make choices, we are generally okay with a bit of "interesting but unlikely to produce anything important", but most of what we fund needs a return on investment.
- maxnoe 9mo agoScience never proves a positive. You can only disprove. The only way to prove a positive if there is a finite number of possibilities and you have disproven all but one. But even then, someone could conceivably come up with an alternate description that preserves the current understanding but makes additional predictions or is a simpler model making the same. As Feyman said: "We can never know if we are right, we can only be certain if we are wrong".
- ChrisArchitect 9mo agoRelated: The string theory hype machine will never die https://news.ycombinator.com/item?id=46621518 https://news.ycombinator.com/item?id=46621518