I definitely don't walk away from any of Brian Greene's content thinking that String Theory is anything close to a confirmed fact at all.
It's been some times since I read his earlier books, possibly his tone has changed?
I'll also say, I'm far from a professional physicist. I'm reading and watching for fun and intellectual curiosity, not to learn physics with the goal of doing my own research. I always thought of String Theory as being more of a study of math where many people have unsuccessfully tried to apply it to physics. And, that it's lead to some really interesting ideas. I just find him and his work really enjoyable.
Thanks for posting that; as soon as I saw the title here I was going to look that up if no one else had already. Sabine Hossenfelder too, though there's far too much content from her on this to put a list, but anyone interested might like some of her takes.
A few debates between Brian and other notables; Hossenfelder, Eric Weinstein, and Roger Penrose to name a few; have popped up in my youtube feed lately which are typically also engaging.
Hossenfelder is not really comparable to Collier. Collier's video is critical of string theory as a testable framework but she ultimately still supports people who do research in string theory. Most of her criticism is with media coverage of string theory, not the research or the researchers.
Hossenfelder has gone off the "the physics establishment is all idiots and they are suppressing the real physics" deep end and has converted specific complaints into trashing the entire field.
I'm not a fan of Hossenfelder, especially for casting quacks like Weinstein, but AFAICT she isn't about "suppressing the real physics" but more of a "establishment physics is wasting money and time, and a lot is equally bad/good as some alternative physics."
Don't agree, she spreads misinformation, she's disrespectful to other scientists and basically has resorted to just claiming that everything in academics is wrong. YouTube fame has completely radicalized her.
> Most of her criticism is with media coverage of string theory, not the research or the researchers.
I pretty strongly disagree with that categorization of Collier's video, as it makes it sound like string theorists were innocent bystanders and "the big bad media" just ran overboard.
I think she puts the blame squarely on string theorists (e.g. "celebrity string theorists who wrote all these books") as constantly hyping up the field with promises of "in a decade it will be amazing" - a phrase she uses to great dramatic effect throughout the video - despite never acknowledging the fact that it fails miserably at making testable predictions.
When she says "they lied to us", the "they" she's clearly talking about are specific researchers in the field (which she names), and the string research community more broadly, who are hyping up their field, not just "the media".
The problem with sabine is that she's become the worst person to make a correct point for the wrong reasons
If you do research it becomes pretty apparent that a high number papers are not great. There's varying issues, but a big one is that the funding model incentivises pumping out papers which are often of low quality, researching whatever happens to be in vogue at the moment
Literally everyone I've ever talked to in research as a frank conversation knows that this is a massive problem, but nobody wants to talk about it publicly. Research funding is already completely screwed as it is, and researchers are incredibly aware of how fragile their livelihoods are
Its clearly leading to a big reduction in the quality of the literature. I went on a replication spree recently and found that a pretty decent chunk of the field I was working in was completely unreplicable by me, with a few papers that I strongly suspect 'massaged' their results for various reasons
I wish someone would talk about this who wasn't also in bed with right wing grifters, and was actually credible. We need someone more like ben goldacre for physics
Sabine's most interesting content is the paper reviews, and where she sticks to actually examining the evidence - but it makes up a tiny fraction of what she produces these days, and her support for some truly grim figures is just gross
The Planck scale where string theory's distinctive physics should appear is around 10^19 GeV. The LHC operates at about 10^4 GeV. That's a factor of 10^15 which is a million billion times too weak. No foreseeable accelerator technology can bridge this gap. The proposed Future Circular Collider (FCC) would reach maybe 10^5 GeV. Still 14 orders of magnitude short.
Non-Euclidean geometry (geometric axioms in which one postulate is rejected such that the 3 angles of a triangle are not exactly 180 degrees) was considered a meaningless word game and fundamental mistruth.
Later, non-Euclidean geometry was actually essential to modern physics.
It's intellectually sketchy to judge future value by the present.
you are mixing up gambling spend vs whole industry spend. If string theory was a small handful of people making up a small m*nority of physics departments like non-euclidea geometry research was that would be fine. Its huge swaths of most physics departments and a huge suck on research funding. For that kind of spend you better show results because you are in production phase at that point not lotto ticket moonshit phase. If we are buying lotto tickets with the money bey lots of different lotto tickets not a whole bunch of one lotto ticket
Might as well fund someone researching whether quantum theory run on little gnomes, if there is no serious path to verification after 50 years, why not quantum gnomes?
Yeah, even just trying chart a course on a ship across a reasonable distance will cause you to need to reevaluate some "obvious" things (like "what path is the shortest between these two ports" being a curve rather than a line).
People often say that the problem with string theory is that it doesn't make any prediction, but that's not quite right: the problem is that it can make almost any prediction you want it to make. It is really less of a "theory" in its own right and more of a mathematical framework for constructing theories.
One day some unusual observation will come along from somewhere, and that will be the loose end that allows someone to start pulling at the whole ball of yarn. Will this happen in our lifetimes? Unlikely, I think.
I am old enough to remember when string theory was expected to explain and unify all forces and predict everything. Sadly, it failed to deliver on that promise.
And there is no known single real world experiment that can rule out string theory while keeping general relativity and quantum mechanics intact.
More accurately, string theory is not wrong (because it just cannot be wrong). Because it does not predict anything and cannot invalidate anything, it does not help to advance our understanding of how to integrate general relativity and quantum mechanics.
It should not be called theory - maybe set of mathematical tools or whatever.
Or, that day will never come, because string theory isn't reflective of the actual world, or because there are so many theories possible under the string theory rubric that we can never find the right one, or because the energies involved to see any effect are far beyond what could be reached in experiment.
It isn't completely implausible that a future civilisation could perform the experiments to gather that data, somehow; but it is hard to envisage how we do it here on Earth.
Your implicit point is a good one. Is it sensible to have a huge chunk of the entire theoretical physics community working endlessly on a theory that could well end up being basically useless? Probably not.
I think that's not quite right: it is reasonably certain that string theory can produce both the standard model and most extensions people have dreamt up, so the problem is rather that all the obviously "stringy" predictions are currently unavailable, while the string theory derived predictions for achievable experiments look like what we get from other theories we already have.
To make this valuable, it should produce a limited set including standard model. If you produce pretty much everything one can dream of, that does not carry predictive power.
What does string theory predict that (1) is within experimental reach in, say, 5 years (2) if not found, would prove it wrong. Was there ever anything satisfying these two simultaneously? AFAIK,the answer is "no".
But we've discovered a number of useful tools and techniques that are applicable to other areas of research have we not? The billions of dollars spent on string theory hype might have unlocked a strategy or technique that ends up being useful in a civilization changing way that we just don't know about yet. Maybe string theory and the hype it was able to generate was just the catalyst that we needed.
Compared to all the other useless endeavors we send our brightest minds to work on (optimizing ad sales, high frequency trading, crypto) I'd say physics research has the highest chance of being useful
Physicist here. My PhD is in an area that was spawned into existence due to inspiration coming from string theory, not string theory proper.
I've made some comments here [1] to discuss how I see the situation. It's difficult to be thorought in the world of research, and even more so in an HN comment. I'll be writing more as the subject pops up in HN.
The legit criticism with a legit recommended change is even better.
A time and technological gap always exists between theory and a plan for experimental confirmation. Some gaps are fairly short. String theory's gap is undoubtedly long, not for lack of resources.
This gap justifies tapering the allocation of attention and research resources (funding, students, etc), which got lopsided following the strong marketing campaign driven by Greene.
I'm legit interested in hearing more about this, like YouTube series, popsci books, magazines - I've been meaning to read Zwiebach's A first course, but I keep getting distracted with background reading and then never get back to it.
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I don't entirely understand where that comes from. The Standard Model and General Relativity are both tested to extreme precision. Any experiment unifying them will have to involve insane energies. It's not as if there is some other model with easy tests that we've agreed to ignore.
As far as I can tell, it seems to come from the developers of Loop Quantum Gravity, who feel left out of funding. And maybe that's true. But their theory doesn't offer practical tests, either. It would be weird if it did.
> I don't entirely understand where that comes from. The Standard Model and General Relativity are both tested to extreme precision. Any experiment unifying them will have to involve insane energies. It's not as if there is some other model with easy tests that we've agreed to ignore.
You're absolutely right in everything you said, thank you.
Like another commenter posted, the planck scale is 10^19 GeV and we're about 10^15 short. Therefore it follows we won't be testing anything at planck scale for many generations, if ever. Therefore the argument of "I can't test it therefore the theory is useless" is just being defeatist. The fact that such theory isn't testable might be a feature of our Universe, not the theory. As in, these people don't normally make the distinction between something that "could be tested in principle, we just don't have the technology" (like string theory) vs something that "couldn't be tested even in principle" (like how many angels can dance on the head of a pin). They're basically playing with semantics when they say "it's not testable".
> As far as I can tell, it seems to come from the developers of Loop Quantum Gravity, who feel left out of funding. And maybe that's true. But their theory doesn't offer practical tests, either. It would be weird if it did.
Again, correct on all points. However, I'll add the following. Yes, LQG makes as many directly-testable predictions at the planck scale as string theory, which is to say none, because we don't have the technology to test anything directly at that scale.
I keep repeating these things on HNs, but people here fundamentally don't understand how research in theoretical physics is done. I'll try a little exposition:
Physics is: make experiments, and try to infer which laws/rules/formulas are common to all experiments or sets of similar experiments, and their domain of applicability. These are called theories.
Theoretical physics is: think about theories, and try to observe which laws/rules/formulas are common to all theories or sets of similar theories, and their domain of applicability. These are more general theories from which your directly-experimented theories can be derived. You can keep interacting constructing ever more general theories from an ever smaller set of principles.
So a lot of theoretical physics is about arguing which of the principles that you know are true because you've experimentally tested them will hold in circumstances where you can't directly test. As it turns out there's a lot that you can infer about things you've never seem because often times mathematics puts constraints on how different ideas work together.
The string theory/LQG thing is that LQG start from the guess that Lorentz invariance doesn't hold at planck scale. The reason why LQG is less appealing to a lot of physicists is that if you follow this through you can never quite make it mathematically self consistent. In string theory what happens in certain sub-domains is that you start with a lot of arbitrary possibilities, but then you demand certain types of mathematical self-consistency and magically it points out that there's only one or a small number possibilities. A classic example is: "how many dimensions does the universe has?" which no theory really gives as answer, but string theory at least points in a direction: "if you assume such and such, the the allowed answers are such and such". This happens a lot in string theory, and it's what drives people to keep digging. String theory on the other hand concludes that Lorentz invariance must hold at all scales "in some string-like theories" if you demand cancellation of divergences, which you must have for your theory to be renormalizable and therefore mathematically self-consistence. So in a sense this is a prediction of string theory. Not that LQG doesn't predict the opposite, that Lorentz invariance doesn't hold. Instead it assumes that it doesn't. String theory instead predicts that it does. The latter is much more impressive; anybody can start from an arbitrarily picked assumption that noone can prove wrong.
Perhaps you could elevate the discussion by providing an actual argument against this view of string theory, which has indeed percolated through social media?
For my part, I know a little bit more than "shit" about physics but I know very little about string theory and know better than to have strongly held opinions about things I don't understand. I've heard quite a lot about the criticisms and would like to hear a defense of it.
Ive been told my multiple High Energy Physicists that String Theory was suspect because it makes no predictions. Being able to make predictions that are testable is a foundation of theoretical science. Not everything is because of influences.
Eh... mainstream physics by numbers is not HEP and definitely not HEP Th, and there are plenty of serious physicists somewhat critical of the field, and more so of the way it presented itself over the last decades.
And while I disagree with some of the criticisms and some of the style of the crtics, it's not like you get an honest appraisal from Greene (and Witten).
i dont think it has anything to do with threats to way of life. It has everything to do with public subsidy of physics that has pushed peripherary mathematics forward without much to show for actual physics advancements. New observations cause changes to string theory not validation of string theory. String theorists can keep do*ng their string theory but its time to subsidize something(so else and see if that leads to actual advancement. I think sabbine hossenfelder is largely correct about this
Theoretical physics is subsidizing a handful of people sitting at white boards.
Even accepting the premise that string theory is wrong I can list hundreds of ways the US budget spews money down black holes orders of magnitude bigger. The spending on string theory isn’t even a rounding error compared to the way my tax dollars are allocated to special interest pork.
But only string theory impinges on a generation of cranks who are convinced they alone have the insight into the true ToE and would be recognized as the new Einstein were it not for some entrenched cabal. Maybe I shouldn’t reflexively trust “big science” or something but it’s also not great to evaluate science by who is more charismatically narcissistic on a podcast.
Again, I don’t have a big axe to grind on the merits here. But it’s hilarious that folks with zero science background past middle school hear some of these cranks on YouTube and feel worthy to decry Witten as an enemy of the people. Between the podcast bro who was just told his ToE was right by ChatGPT and Witten I’ll take Witten.
I know absolutely nothing about string theory, or the culture of high-energy physics, but I don't buy the pecuniary argument you are making. You aren't considering the downwind effects of allowing academic rot. The Bourbaki—and their acolytes—also sponged up only a tiny amount of academic funding, but a fever in the pulpit can spread out into the pews; we've seen the "New Math" paradigm damage a generation of primary-and-secondary-school students. Even today, we have issues with engineers not understanding that a derivative is a slope and an integral is an area—due in no small part to a cartel of bad actors in mathematical research. Allowing bad behavior in high-value and influential positions has consequences beyond a waste of government expenditure; a president could turn a democracy into a banana republic, and we would have issues beyond his salary of a few hundred thousand dollars being wasted.
How many primary school students can't add fractions because string theory may be a less promising approach to a ToE versus loop quantum gravity or geometric unity? I know nothing about this stuff. You know nothing about this stuff. Since we both do know about the Bourbaki school of mathematics despite having different opinions on the value of building mathematics upward from foundational principles I'd say we are in the top .5% of the planet re general mathematical/scientific literacy. So I don't buy that even if string theory is wrong there is some massive spillover effect.
No, its subsidizing a handful of people sitting at whiteboards at the expense of different camps of people sitting at whiteboards and the result is nefarious because you dont see what could have been if we minimized string theory funding after a decade or two of poor performance instead of going all in on it for five decades. We gave up decades of potentially actually figuring something new out by going harder on string theory instead of diversifying physics spend as performance failed to show up.
how the government wastes money elsewhere is irrelevant to the conversation. Its about proper management of research funding and how string theorists managed tp trick us into funding failure for whole academic careers.
Since I sadly must return to the real world (but thank you everyone for the well spirited debate) -- string theory is funny to me because its a bit of a Rorschach test as such a tiny number of people who follow the subject can actually evaluate string theory vs. alternative models. It's just an abstract blob people can project their worldview onto. To the extent someone reading this is in the group who does understand the topic, this isn't about you--
As a society we can't place excess faith in the orthodox positions of institutions. We all know they can be rigid, wrong, and lock out dissenting views. But society today seems to embrace heterodoxy for its own sake the way perhaps in the past orthodoxy was just accepted on pure faith and there is a vast media ecosystem happy to promote (ie monetize) this worldview. Just because something is heterodox doesn't make it right.
Again, I'll accept your premise for the sake of debate (which I welcome, and sincerely thank you for doing so respectfully).
Let me try to rephrase where I am coming from. I'm going to accept there is a good argument that some science funding should be redirected towards theoretical physicists pursuing alternate approaches.
1. The focus towards this matter in online media circles is vastly disproportionate to the relative impact this has on anyone's life compared to the multitude of other intra-silo disputes across the federal budget. It's not irrelevant to the conversation or at least my subsection of the conversation. It is interesting to me what debates burst through the noise and get traction outside of their own little world. Maybe 1% of the people debating string theory online actually understand a micro-fraction of this stuff. To be clear, I don't claim to be in that 1%. I'm interested in how that happened and the cultural+platform reasons for it. I'm interested in why alongside those genuinely interested in alternative approaches to theoretical physics this topic attracts tons of people who just lump it in with their "they are all lying to you" worldview. Nothing this obscure, incomprehensible, and yes irrelevant to most peoples lives should have organically reached such breakout status. I can ask some of the 22 year old bros at my jiu jitsu gym what they think of string theory and they will tell me it's all part of the omni-conspiracy. It's literally the only science thing they know. It's not like they understand a word of the debate or know of/care about a single other intra-discipline debate about the allocation of resources.
2. No small part of this is the unfortunate emergence of the online narcissist huckster and nothing plays better in online circles than "they" don't want you to know the truth that "I" have the true answer but "Big X" won't admit it. This clown show distracts from the real merits of the relative positions. But it does get the charismatic narcissist a slot on general interest "they are all always lying to you" podcasts.
3. Obviously this doesn't apply to legit physicists and good faith normies who simply disagree with the existing dogma. That's not who I'm talking about. That said, theoretical physics is bargain basement cheap. I don't need to build a supercollider the size of Mars. I don't need to sequence a trillion genomes. I need a laptop, a whiteboard, some time to think, and a bit of ancillary budget. Surely there are enough allied tech/crypto heterodox rich dudes at this point to fund a Center for Heterodox ToEs and staff it with 50 bright people to prove they have something to add. I can't pretend to have the chops to analyze Eric Weinstein's Geometric Unity vs String Theory. I do know if I really thought I had the answer to the universe and his bankroll/connections I'd just fund a real research effort to prove it vs. doing the podcast circuit ad infinitum.
Honestly that kind of straw man is about equally as grating as the "string theory critics" that watched 1 Sabine Hossenfelder video. And just as uninteresting.
I thought Brian Greene did a great job interviewing Edward Witten (Fields Medal winner) on the World Science Festival Youtube channel [1].
I also just really enjoy Brian Greene, his books, and the World Science Festival Youtube channel.
[1] https://www.youtube.com/watch?v=sAbP0magTVY
You might not like Angela Collier's video on string theory[1].
[1]: https://m.youtube.com/watch?v=kya_LXa_y1E
Interesting, thanks for sharing!
I definitely don't walk away from any of Brian Greene's content thinking that String Theory is anything close to a confirmed fact at all.
It's been some times since I read his earlier books, possibly his tone has changed?
I'll also say, I'm far from a professional physicist. I'm reading and watching for fun and intellectual curiosity, not to learn physics with the goal of doing my own research. I always thought of String Theory as being more of a study of math where many people have unsuccessfully tried to apply it to physics. And, that it's lead to some really interesting ideas. I just find him and his work really enjoyable.
Thanks for posting that; as soon as I saw the title here I was going to look that up if no one else had already. Sabine Hossenfelder too, though there's far too much content from her on this to put a list, but anyone interested might like some of her takes.
A few debates between Brian and other notables; Hossenfelder, Eric Weinstein, and Roger Penrose to name a few; have popped up in my youtube feed lately which are typically also engaging.
Hossenfelder is not really comparable to Collier. Collier's video is critical of string theory as a testable framework but she ultimately still supports people who do research in string theory. Most of her criticism is with media coverage of string theory, not the research or the researchers.
Hossenfelder has gone off the "the physics establishment is all idiots and they are suppressing the real physics" deep end and has converted specific complaints into trashing the entire field.
I'm not a fan of Hossenfelder, especially for casting quacks like Weinstein, but AFAICT she isn't about "suppressing the real physics" but more of a "establishment physics is wasting money and time, and a lot is equally bad/good as some alternative physics."
I think here more recent takes are not nearly as nuanced.
Yeah I think most of what (negative) people attribute to her is mostly her being hopelessly German.
Most, but not all
Don't agree, she spreads misinformation, she's disrespectful to other scientists and basically has resorted to just claiming that everything in academics is wrong. YouTube fame has completely radicalized her.
> Most of her criticism is with media coverage of string theory, not the research or the researchers.
I pretty strongly disagree with that categorization of Collier's video, as it makes it sound like string theorists were innocent bystanders and "the big bad media" just ran overboard.
I think she puts the blame squarely on string theorists (e.g. "celebrity string theorists who wrote all these books") as constantly hyping up the field with promises of "in a decade it will be amazing" - a phrase she uses to great dramatic effect throughout the video - despite never acknowledging the fact that it fails miserably at making testable predictions.
When she says "they lied to us", the "they" she's clearly talking about are specific researchers in the field (which she names), and the string research community more broadly, who are hyping up their field, not just "the media".
I thought her rant about bullshit papers was pretty convincing and poignant.
The problem with sabine is that she's become the worst person to make a correct point for the wrong reasons
If you do research it becomes pretty apparent that a high number papers are not great. There's varying issues, but a big one is that the funding model incentivises pumping out papers which are often of low quality, researching whatever happens to be in vogue at the moment
Literally everyone I've ever talked to in research as a frank conversation knows that this is a massive problem, but nobody wants to talk about it publicly. Research funding is already completely screwed as it is, and researchers are incredibly aware of how fragile their livelihoods are
Its clearly leading to a big reduction in the quality of the literature. I went on a replication spree recently and found that a pretty decent chunk of the field I was working in was completely unreplicable by me, with a few papers that I strongly suspect 'massaged' their results for various reasons
I wish someone would talk about this who wasn't also in bed with right wing grifters, and was actually credible. We need someone more like ben goldacre for physics
Sabine's most interesting content is the paper reviews, and where she sticks to actually examining the evidence - but it makes up a tiny fraction of what she produces these days, and her support for some truly grim figures is just gross
Collier made a video fairly recently where she showed disappointment that her videos are watched by people who also watch Hossenfelder.
https://youtu.be/miJbW3i9qQc
The Planck scale where string theory's distinctive physics should appear is around 10^19 GeV. The LHC operates at about 10^4 GeV. That's a factor of 10^15 which is a million billion times too weak. No foreseeable accelerator technology can bridge this gap. The proposed Future Circular Collider (FCC) would reach maybe 10^5 GeV. Still 14 orders of magnitude short.
So the grift can continue
Non-Euclidean geometry (geometric axioms in which one postulate is rejected such that the 3 angles of a triangle are not exactly 180 degrees) was considered a meaningless word game and fundamental mistruth.
Later, non-Euclidean geometry was actually essential to modern physics.
It's intellectually sketchy to judge future value by the present.
you are mixing up gambling spend vs whole industry spend. If string theory was a small handful of people making up a small m*nority of physics departments like non-euclidea geometry research was that would be fine. Its huge swaths of most physics departments and a huge suck on research funding. For that kind of spend you better show results because you are in production phase at that point not lotto ticket moonshit phase. If we are buying lotto tickets with the money bey lots of different lotto tickets not a whole bunch of one lotto ticket
Might as well fund someone researching whether quantum theory run on little gnomes, if there is no serious path to verification after 50 years, why not quantum gnomes?
Ideally, one should explore all possibilities. It is remarkable how far "merely" predicting the next word has taken us.
That was constant progress with measurable goals, not "big things are coming decade from now" every decade.
In the 1700s, perhaps. But we have come a long way since that.
I imagine that elliptic geometry had some use before modern physics.
Yeah, even just trying chart a course on a ship across a reasonable distance will cause you to need to reevaluate some "obvious" things (like "what path is the shortest between these two ports" being a curve rather than a line).
Planck energy: ~10^19 GeV is approx 2 GJ per collision
Energy to vaporize Earth's oceans: ~4 x 10^27 J
For a Planck-scale linear collider at LHC-like collision rates (~10^8/sec):
Beam power requirement: ~2 x 10^17 W
With realistic wall-plug efficiency of ~1%: ~2 x 10^19 W
Annual energy consumption: ~6 x 10^26 J
At 1% efficiency, one year of operation would:
Vaporize about 15% of Earth's oceans
Or vaporize the Mediterranean Sea roughly 50 times
Or boil Lake Superior every 5 hours
Or one complete ocean vaporization every 6-7 years of operation
It's about 1 million times current global power consumption
Or about 50,000 Suns running continuously
Or 170 billion Large Hadron Colliders operating simultaneously
People often say that the problem with string theory is that it doesn't make any prediction, but that's not quite right: the problem is that it can make almost any prediction you want it to make. It is really less of a "theory" in its own right and more of a mathematical framework for constructing theories.
One day some unusual observation will come along from somewhere, and that will be the loose end that allows someone to start pulling at the whole ball of yarn. Will this happen in our lifetimes? Unlikely, I think.
I am old enough to remember when string theory was expected to explain and unify all forces and predict everything. Sadly, it failed to deliver on that promise.
And there is no known single real world experiment that can rule out string theory while keeping general relativity and quantum mechanics intact.
More accurately, string theory is not wrong (because it just cannot be wrong). Because it does not predict anything and cannot invalidate anything, it does not help to advance our understanding of how to integrate general relativity and quantum mechanics.
It should not be called theory - maybe set of mathematical tools or whatever.
Or, that day will never come, because string theory isn't reflective of the actual world, or because there are so many theories possible under the string theory rubric that we can never find the right one, or because the energies involved to see any effect are far beyond what could be reached in experiment.
It isn't completely implausible that a future civilisation could perform the experiments to gather that data, somehow; but it is hard to envisage how we do it here on Earth.
Your implicit point is a good one. Is it sensible to have a huge chunk of the entire theoretical physics community working endlessly on a theory that could well end up being basically useless? Probably not.
An in half a century we still haven't found a single actually testable prediction.
I think that's not quite right: it is reasonably certain that string theory can produce both the standard model and most extensions people have dreamt up, so the problem is rather that all the obviously "stringy" predictions are currently unavailable, while the string theory derived predictions for achievable experiments look like what we get from other theories we already have.
To make this valuable, it should produce a limited set including standard model. If you produce pretty much everything one can dream of, that does not carry predictive power.
What does string theory predict that (1) is within experimental reach in, say, 5 years (2) if not found, would prove it wrong. Was there ever anything satisfying these two simultaneously? AFAIK,the answer is "no".
Making a hard, arbitrary deadline is a pretty extreme thing to do. ie Higgs Boson was a lot longer between theory and experiment than this.
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But we've discovered a number of useful tools and techniques that are applicable to other areas of research have we not? The billions of dollars spent on string theory hype might have unlocked a strategy or technique that ends up being useful in a civilization changing way that we just don't know about yet. Maybe string theory and the hype it was able to generate was just the catalyst that we needed.
what didn't se develop because those people were working on string theory? That is an unanswerable question. It is also the important question.
Compared to all the other useless endeavors we send our brightest minds to work on (optimizing ad sales, high frequency trading, crypto) I'd say physics research has the highest chance of being useful
I wonder what Ed Witten would have accomplished if he had gone into another field instead of choosing to dedicate his life to mathematical physics.
You reminded me about this Abstruse Goose comic: https://web.archive.org/web/20230202225744/https://abstruseg...
Not sure if you're making a joke about this, but Ed Witten tried a number of fields before settling on theoretical physics.
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Physicist here. Would you like to enrich our world view by linking to counter-examples?
My understanding was that string theory being more "hypothetical physics" than "theoretical physics" at this point is still a pretty legit criticism.
Physicist here. My PhD is in an area that was spawned into existence due to inspiration coming from string theory, not string theory proper.
I've made some comments here [1] to discuss how I see the situation. It's difficult to be thorought in the world of research, and even more so in an HN comment. I'll be writing more as the subject pops up in HN.
[1] https://news.ycombinator.com/item?id=46336655
The legit criticism with a legit recommended change is even better.
A time and technological gap always exists between theory and a plan for experimental confirmation. Some gaps are fairly short. String theory's gap is undoubtedly long, not for lack of resources.
This gap justifies tapering the allocation of attention and research resources (funding, students, etc), which got lopsided following the strong marketing campaign driven by Greene.
I'm legit interested in hearing more about this, like YouTube series, popsci books, magazines - I've been meaning to read Zwiebach's A first course, but I keep getting distracted with background reading and then never get back to it.
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Wow their comment history isn’t much better, is there downside or anything that repeat low-value commenters face?
I've had dang on my case, threatening to ban me if I kept it up.
Rather than inb4, you'll make a stronger case by rebutting any of those comments you see come up in the thread.
Not really a rebuttal, but a discussion of how I see the situation: https://news.ycombinator.com/item?id=46336655
I don't entirely understand where that comes from. The Standard Model and General Relativity are both tested to extreme precision. Any experiment unifying them will have to involve insane energies. It's not as if there is some other model with easy tests that we've agreed to ignore.
As far as I can tell, it seems to come from the developers of Loop Quantum Gravity, who feel left out of funding. And maybe that's true. But their theory doesn't offer practical tests, either. It would be weird if it did.
> I don't entirely understand where that comes from. The Standard Model and General Relativity are both tested to extreme precision. Any experiment unifying them will have to involve insane energies. It's not as if there is some other model with easy tests that we've agreed to ignore.
You're absolutely right in everything you said, thank you.
Like another commenter posted, the planck scale is 10^19 GeV and we're about 10^15 short. Therefore it follows we won't be testing anything at planck scale for many generations, if ever. Therefore the argument of "I can't test it therefore the theory is useless" is just being defeatist. The fact that such theory isn't testable might be a feature of our Universe, not the theory. As in, these people don't normally make the distinction between something that "could be tested in principle, we just don't have the technology" (like string theory) vs something that "couldn't be tested even in principle" (like how many angels can dance on the head of a pin). They're basically playing with semantics when they say "it's not testable".
> As far as I can tell, it seems to come from the developers of Loop Quantum Gravity, who feel left out of funding. And maybe that's true. But their theory doesn't offer practical tests, either. It would be weird if it did.
Again, correct on all points. However, I'll add the following. Yes, LQG makes as many directly-testable predictions at the planck scale as string theory, which is to say none, because we don't have the technology to test anything directly at that scale.
I keep repeating these things on HNs, but people here fundamentally don't understand how research in theoretical physics is done. I'll try a little exposition:
Physics is: make experiments, and try to infer which laws/rules/formulas are common to all experiments or sets of similar experiments, and their domain of applicability. These are called theories.
Theoretical physics is: think about theories, and try to observe which laws/rules/formulas are common to all theories or sets of similar theories, and their domain of applicability. These are more general theories from which your directly-experimented theories can be derived. You can keep interacting constructing ever more general theories from an ever smaller set of principles.
So a lot of theoretical physics is about arguing which of the principles that you know are true because you've experimentally tested them will hold in circumstances where you can't directly test. As it turns out there's a lot that you can infer about things you've never seem because often times mathematics puts constraints on how different ideas work together.
The string theory/LQG thing is that LQG start from the guess that Lorentz invariance doesn't hold at planck scale. The reason why LQG is less appealing to a lot of physicists is that if you follow this through you can never quite make it mathematically self consistent. In string theory what happens in certain sub-domains is that you start with a lot of arbitrary possibilities, but then you demand certain types of mathematical self-consistency and magically it points out that there's only one or a small number possibilities. A classic example is: "how many dimensions does the universe has?" which no theory really gives as answer, but string theory at least points in a direction: "if you assume such and such, the the allowed answers are such and such". This happens a lot in string theory, and it's what drives people to keep digging. String theory on the other hand concludes that Lorentz invariance must hold at all scales "in some string-like theories" if you demand cancellation of divergences, which you must have for your theory to be renormalizable and therefore mathematically self-consistence. So in a sense this is a prediction of string theory. Not that LQG doesn't predict the opposite, that Lorentz invariance doesn't hold. Instead it assumes that it doesn't. String theory instead predicts that it does. The latter is much more impressive; anybody can start from an arbitrarily picked assumption that noone can prove wrong.
Perhaps you could elevate the discussion by providing an actual argument against this view of string theory, which has indeed percolated through social media?
For my part, I know a little bit more than "shit" about physics but I know very little about string theory and know better than to have strongly held opinions about things I don't understand. I've heard quite a lot about the criticisms and would like to hear a defense of it.
I have a lot more to say, but I wrote a little bit here: https://news.ycombinator.com/item?id=46336655
Ive been told my multiple High Energy Physicists that String Theory was suspect because it makes no predictions. Being able to make predictions that are testable is a foundation of theoretical science. Not everything is because of influences.
Eh... mainstream physics by numbers is not HEP and definitely not HEP Th, and there are plenty of serious physicists somewhat critical of the field, and more so of the way it presented itself over the last decades.
And while I disagree with some of the criticisms and some of the style of the crtics, it's not like you get an honest appraisal from Greene (and Witten).
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i dont think it has anything to do with threats to way of life. It has everything to do with public subsidy of physics that has pushed peripherary mathematics forward without much to show for actual physics advancements. New observations cause changes to string theory not validation of string theory. String theorists can keep do*ng their string theory but its time to subsidize something(so else and see if that leads to actual advancement. I think sabbine hossenfelder is largely correct about this
Theoretical physics is subsidizing a handful of people sitting at white boards.
Even accepting the premise that string theory is wrong I can list hundreds of ways the US budget spews money down black holes orders of magnitude bigger. The spending on string theory isn’t even a rounding error compared to the way my tax dollars are allocated to special interest pork.
But only string theory impinges on a generation of cranks who are convinced they alone have the insight into the true ToE and would be recognized as the new Einstein were it not for some entrenched cabal. Maybe I shouldn’t reflexively trust “big science” or something but it’s also not great to evaluate science by who is more charismatically narcissistic on a podcast.
Again, I don’t have a big axe to grind on the merits here. But it’s hilarious that folks with zero science background past middle school hear some of these cranks on YouTube and feel worthy to decry Witten as an enemy of the people. Between the podcast bro who was just told his ToE was right by ChatGPT and Witten I’ll take Witten.
I know absolutely nothing about string theory, or the culture of high-energy physics, but I don't buy the pecuniary argument you are making. You aren't considering the downwind effects of allowing academic rot. The Bourbaki—and their acolytes—also sponged up only a tiny amount of academic funding, but a fever in the pulpit can spread out into the pews; we've seen the "New Math" paradigm damage a generation of primary-and-secondary-school students. Even today, we have issues with engineers not understanding that a derivative is a slope and an integral is an area—due in no small part to a cartel of bad actors in mathematical research. Allowing bad behavior in high-value and influential positions has consequences beyond a waste of government expenditure; a president could turn a democracy into a banana republic, and we would have issues beyond his salary of a few hundred thousand dollars being wasted.
How many primary school students can't add fractions because string theory may be a less promising approach to a ToE versus loop quantum gravity or geometric unity? I know nothing about this stuff. You know nothing about this stuff. Since we both do know about the Bourbaki school of mathematics despite having different opinions on the value of building mathematics upward from foundational principles I'd say we are in the top .5% of the planet re general mathematical/scientific literacy. So I don't buy that even if string theory is wrong there is some massive spillover effect.
No, its subsidizing a handful of people sitting at whiteboards at the expense of different camps of people sitting at whiteboards and the result is nefarious because you dont see what could have been if we minimized string theory funding after a decade or two of poor performance instead of going all in on it for five decades. We gave up decades of potentially actually figuring something new out by going harder on string theory instead of diversifying physics spend as performance failed to show up.
how the government wastes money elsewhere is irrelevant to the conversation. Its about proper management of research funding and how string theorists managed tp trick us into funding failure for whole academic careers.
Since I sadly must return to the real world (but thank you everyone for the well spirited debate) -- string theory is funny to me because its a bit of a Rorschach test as such a tiny number of people who follow the subject can actually evaluate string theory vs. alternative models. It's just an abstract blob people can project their worldview onto. To the extent someone reading this is in the group who does understand the topic, this isn't about you--
As a society we can't place excess faith in the orthodox positions of institutions. We all know they can be rigid, wrong, and lock out dissenting views. But society today seems to embrace heterodoxy for its own sake the way perhaps in the past orthodoxy was just accepted on pure faith and there is a vast media ecosystem happy to promote (ie monetize) this worldview. Just because something is heterodox doesn't make it right.
Have a wonderful weekend all.
Again, I'll accept your premise for the sake of debate (which I welcome, and sincerely thank you for doing so respectfully).
Let me try to rephrase where I am coming from. I'm going to accept there is a good argument that some science funding should be redirected towards theoretical physicists pursuing alternate approaches.
1. The focus towards this matter in online media circles is vastly disproportionate to the relative impact this has on anyone's life compared to the multitude of other intra-silo disputes across the federal budget. It's not irrelevant to the conversation or at least my subsection of the conversation. It is interesting to me what debates burst through the noise and get traction outside of their own little world. Maybe 1% of the people debating string theory online actually understand a micro-fraction of this stuff. To be clear, I don't claim to be in that 1%. I'm interested in how that happened and the cultural+platform reasons for it. I'm interested in why alongside those genuinely interested in alternative approaches to theoretical physics this topic attracts tons of people who just lump it in with their "they are all lying to you" worldview. Nothing this obscure, incomprehensible, and yes irrelevant to most peoples lives should have organically reached such breakout status. I can ask some of the 22 year old bros at my jiu jitsu gym what they think of string theory and they will tell me it's all part of the omni-conspiracy. It's literally the only science thing they know. It's not like they understand a word of the debate or know of/care about a single other intra-discipline debate about the allocation of resources. 2. No small part of this is the unfortunate emergence of the online narcissist huckster and nothing plays better in online circles than "they" don't want you to know the truth that "I" have the true answer but "Big X" won't admit it. This clown show distracts from the real merits of the relative positions. But it does get the charismatic narcissist a slot on general interest "they are all always lying to you" podcasts. 3. Obviously this doesn't apply to legit physicists and good faith normies who simply disagree with the existing dogma. That's not who I'm talking about. That said, theoretical physics is bargain basement cheap. I don't need to build a supercollider the size of Mars. I don't need to sequence a trillion genomes. I need a laptop, a whiteboard, some time to think, and a bit of ancillary budget. Surely there are enough allied tech/crypto heterodox rich dudes at this point to fund a Center for Heterodox ToEs and staff it with 50 bright people to prove they have something to add. I can't pretend to have the chops to analyze Eric Weinstein's Geometric Unity vs String Theory. I do know if I really thought I had the answer to the universe and his bankroll/connections I'd just fund a real research effort to prove it vs. doing the podcast circuit ad infinitum.
Honestly that kind of straw man is about equally as grating as the "string theory critics" that watched 1 Sabine Hossenfelder video. And just as uninteresting.