20 ms·

20 Years Later

412 points by jjgreen 6y ago

jagged-chisel 6y ago
> Almost exactly twenty years ago I started writing a short article about the problems with string theory. [...] The piece was done in a week or two, after which I sent it around to a group of physicists to ask for comments. The reaction was mostly positive, although at least one well-known theorist told me that publicly challenging string theorists in this way would be counter-productive. I like to know the subject before I wander off HN following a nondescript title...
- throwaway98797 6y ago
  Domain name should give a clue. Plus, a little bit of randomness is the spice of life.
  - CyberDildonics 6y ago
    Don't rationalize clickbait. This site doesn't allow comments without substance, but for some reason link titles don't have the same standards.
    - hyperpape 6y ago
      The title wasn't written for you, but that doesn't make it clickbait. That's true even though it's not a great title. The author is a physicist/computer scientist writing on his personal blog. He is writing about some of his own work, 20 years later, and his likely audience probably has context about that work, or will be linked from somewhere that provides that context. The fact that you and I stumbled upon it from a decontextualized aggregator is a bug.
      - CyberDildonics 6y ago
        It wouldn't be a bug if there was more information than "20 years later"
      - fireattack 6y ago
        Totally unrelated, but why is he in Math department instead of Physics?
        cambalache 6y ago
        Peter Woit(the author) is a lecturer in the department of mathematics at Columbia University. He is kind of a black sheep in the high-energy physics world. He has a PhD in physics from Harvard, so he certainly has the credentials but his academic career stalled/never took off, so after some post-docs he took a job at Columbia teaching mathematics and maintaining the computer network of the department. A fact that has not passed unnoticed by his "enemies"(many string theorists),so they use that to mock him and dismiss his not entirely unreasonable criticism of ST. That shows you that eminent physicists can be as tribalistic, petty and emotional as a stereotypical 14 year old girl.
    - segfaultbuserr 6y ago
      No, clickbaits are usually disallowed in the title. The rule is use original title, most of the time it's indeed an anti-clickbait rule (although some false negatives are unavoidable). > Please don't do things to make titles stand out, like using uppercase or exclamation points, or saying how great an article is. It's implicit in submitting something that you think it's important. > [...] Please use the original title, unless it is misleading or linkbait; don't editorialize. My personal observation, there are three types of bad titles. 1. Clickbait titles editorialized by a submitter to make everyone know how great/important the article is. 2. Clickbait titles from the source. 3. Non-descriptive title from the source. 60% of the bad titles are Type-1 title from the submitters (as everyone who ever browsed Reddit would know). To prevent such behaviors, the "use original title" rule is implemented on Hacker News. 30% of the titles are Type-2 title. On Hacker News, if many readers loudly criticize that the original title is misleading, eventually a moderator will correct it manually. 10% of the titles are Type-3 title, non-descriptive title that contain little information, but it's neither misleading or clickbait. On Hacker News, usually, nothing happens. This article is one of them. Also, any attempt to change the title could be seen as Type-1 title editorialization, so the original title remains. So sometimes, even after the title has been changed by the submitter to be more descriptive, it could be reverted back to the original, non-descriptive one. > This site doesn't allow comments without substance, but for some reason link titles don't have the same standards. Whenever people compliant that Hacker News allows non-descriptive titles, please consider the fact that "use the original title" does more good than harm in general with a false negative rate of only 10%, which is a small price to pay.
  - AnimalMuppet 6y ago
    The domain name doesn't give me a clue that it's about physics, instead of, say, sociology or something.
    - throwaway98797 6y ago
      Okay princess.
- raldi 6y ago
  Thank you. I came to the comments hoping for exactly this.
- jjgreen 6y ago
  Sorry about that, just following the submission guidelines [1] but should have left an explanatory initial comment I guess ... [1] https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
  - jagged-chisel 6y ago
    Hey, no worries. The title is definitely not your fault. :)
  - Exmoor 6y ago
    I almost certainly would have never clicked on an article about String Theory, even if it was trending at #1, but because of the vague title I did and was happily surprised to learn something about the world of physics and physics researchers.
- deleted 6y ago
  [deleted]
- idlewords 6y ago
  Thoughts and prayers to you in this challenging time.
hardtke 6y ago
One of the biggest problems in science (in general) is that your reputation and therefore funding is highly tied to a particular subfield. Everyone in a subfield knows each other and gives positive grant reviews and external tenure letters to other practitioners. If you try to move on to new areas of research, your reputation and funding are gone. The outcome is that areas of research interest become quasi-permanent, even when they are no longer interesting. I talk to the people today that still work in my specialty of nuclear physics (relativistic heavy ion physics) and I'm shocked at how little intellectual progress has been made. At the risk of offending people it's time to give up and declare victory, but the consequences would be dire (hundreds of professors all over the world without grants).
- marta_morena_9 6y ago
  If there is funding, there is apparently a need for research. The solution is never for the individuals to induce change. This doesn't work for consumers (i.e. you can't say "If everyone stops buying plastic bags, we do something for the environment", because well, nobody cares... You have to make selling plastic bags either illegal or add a significant surcharge that causes consumers to avoid them for reasons that actually affect them, like "too expensive") And it doesn't work for anything else either. As long as there is funding, this will go on. The "solution" is to stop funding, but apparently since funding is still flowing, someone still values the research. So what is even the problem? No progress has been made? Well, if funding is still there, whoever funds this seems to be beyond happy with the progress. This is a non-issue.
  - xapata 6y ago
    Perhaps the issue is that the funding agency is not sophisticated enough to realize that there's no value, or more value elsewhere?
    - wadkar 6y ago
      OR perhaps the issue that the same people who are in the clique of the said field are also evaluating the research proposals. So the funding doesn’t run dry? Not that that’s a good or bad thing. You wouldn’t want a “non-expert” to evaluate the proposal. And perhaps a tapering of the funding is better indicator of interest/progress of the field?
whatshisface 6y ago
What is there around to replace string theory with? I predict that if there ever is a viable alternative available with even 0.001% more evidence supporting it, strings will vanish in a day. Presently all other approaches to quantum gravity are in a less developed state and make even fewer predictions.
- Iwan-Zotow 6y ago
  Fewer than 0? How come?
  - whatshisface 6y ago
    String theory at least predicts gravity in three dimensions. Other approaches to quantum gravity are not even far enough along to do that - it was an immense and relatively recent accomplishment to have LQG on a circle.
    - guscost 6y ago
      String theory has not made predictions that are in any sense meaningful to science. “Confirmations should count only if they are the result of risky predictions; that is to say, if, unenlightened by the theory in question, we should have expected an event which was incompatible with the theory--an event which would have refuted the theory.” - Popper
      - whatshisface 6y ago
        >String theory has not made predictions that are in any sense meaningful to science. You're welcome to set the bar of meaningful at any level you like; such a statement cannot in principle be disagreed with. However the point stands that string theory has made more accurate empirical predictions than any other theory of quantum gravity. That doesn't mean no other theory of quantum gravity will ever beat it, just that the focus on string theory among people and funders who are precomitted to studying quantum gravity is rational.
l0b0 6y ago
I can't help but feel cynical about this piece: 1. 20 years ago the author wrote a paper asserting that string theory was a fruitless field of study. 2. The paper is written in a confrontational and snarky tone, for example: "The theory has been spectacularly successful on one front, that of public relations." Not a way to build bridges. 3. The author seems bitter that the paper wasn't accepted into Physics Today, and that the suggested rewriting into a letter to the editor did not result in publication either. 4. The author is sticking to their guns. No matter how well-founded the idea that string theory is a dead end, this isn't likely to improve things.
- meowkit 6y ago
  Hard disagree on #3. He seems annoyed that he didn’t get any followup, which is totally warranted.
  - l0b0 6y ago
    I assume a publication like Physics Today gets a lot of submissions, and that probably the majority of them are rejected. Maybe there would've been a better chance of acceptance if the article (and presumably also the letter to the editor) wasn't so confrontational.
    - cycomanic 6y ago
      Physics today is not a scientific journal. I highly doubt that they get a lot of submissions. In my experience with similar publications in a different subfield it's typically more that the journalists/editors at those magazines think that some topic is interesting and talk to some of the more famous researchers in the field to write an article. Sometimes it's also a bit the other way around and the researchers suggest articles to editors they know. Not to publish a letter to the editor seems a very strange decision, these are very short letters and sometimes really cover some quite niche topics. Also not getting back to the author after asking him to rewrite in a different format is just bad form.
- hitekker 6y ago
  The scientist saw BS, he called BS, and then 20 years later, the field he criticized turned out to be mostly BS. If you're offended by the audacity of scientists criticizing pseudoscience, you may want to read about the concept of "polemics". It's an acceptable, longstanding form of rhetoric for when a respected figure publicly disagrees with a direction of another group of people. https://en.wikipedia.org/wiki/Polemic https://en.wikipedia.org/wiki/Polemic Incidentally, the author even noted his article was a polemic in the original abstract https://arxiv.org/abs/physics/0102051 https://arxiv.org/abs/physics/0102051
dilippkumar 6y ago
Is there a popular science book that begins with Noether’s theorem (along with some biographical details and historical context in which her theorem must be understood) and traces developments from there down to the Standard Model and talks about what the standard model doesn’t solve and why new theories are interesting? Preferably a book that doesn’t go off into the deep end with alternate realities and dead/alive cats in boxes. I read Higgs by Jim Baggot, it did a good job of providing an overview - however I would like something that goes into a little more detail while still being a popular science book.
- deleted 6y ago
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- whatshisface 6y ago
  I don't understand how you could imagine having a discussion about "what the standard model doesn’t solve and why new theories are interesting," that wasn't in the language of quantum mechanics, which the dead/alive cats in boxes thing would be an elementary first step of learning. Field theory is way farther off the deep end than the measurement of a two-state system.
  - centimeter 6y ago
    There are several languages with which you can discuss the standard model, particularly Group Theory, which I don't think require much familiarity with the details of QM. I assume this is what the GP is talking about given his mention of Noether currents. I say this as someone who is quite familiar with QM, so it's very possible I'm just neglecting to consider all the implicit context I'm working with.
    - whatshisface 6y ago
      Group theory has applications in QM, but you can't go from the standard model to experimental results through group theory alone. To do that, you need to understand all of the physics concepts leading up to it. Even knowing what a conserved quantity is involves some of that implicit context you're talking about.
Scene_Cast2 6y ago
I find that in big organizations, this is is a very frequent pattern. There is a commonly accepted approach that is obviously wrong to a subset of people. However, the people that are able to see the "wrongness" either don't have the political skills to accelerate a mental shift for the entire organization, or they choose to apply their limited "political leverage" to a different (often smaller and more tractable) problem instead.
jariel 6y ago
The key quote: "The tribalistic sociology that has led to a large group of people calling themselves “string theorists” when what they do has nothing to do with string theory is also something I would have thought impossible." It's my personal bias but I see every group this way. As someone intrigued by 'cults' early in life, I've come to see that all groups exhibit quite a lot of in/out group behaviour, the weird things is when it happens among those most socially unaware people (often science) - combined with a highly objective discipline (again science) ... people are just unwilling to accept that social artifacts can dominate their sphere. Now, the existential issue of the fact that their 'entire worldview' and 'life-long work' is tied up in something, delusions can become very strongly internalized. String theory is at least as interesting for the 'sociology' part as it is the 'string' part. String theory, and the 'reproducability problem' has kind of shaken my faith in science. I grew up really 'believing' in Science, I view it much more differently these days - including those who have this unassailable faith in it as likely being a little deluded themselves.
- pdonis 6y ago
  > It's my personal bias but I see every group this way. I have the same "bias". What people seem to forget is that the scientific method was supposed to be a way to develop theories that made good predictions in spite of the fact that humans, both individually and in groups, are unreliable and do all sorts of crazy things for all sorts of crazy reasons. Calling oneself a "scientist" or having an advanced degree does not make one less susceptible to that. One has to set up institutions that will harness the craziness of humans and human groups in a direction that, on average and over the long term, is productive. But what most people call "science" today is not such an institution. For example, the real message of the "replication crisis" is that most of what the average person is told is "science" is actually nothing of the sort. A sane institution of science would never have labelled that stuff as "science" in the first place; it would have said "sorry, we're still working on this, no results yet". And a lot of times it would say that and there never would be any results, and science would say "no results from this line of research; that's to be expected since many lines of research that initially look promising don't pan out".
  - 6y ago
frongpik 6y ago
IIRC, one big problem of the strings theory was the shape of those strings: the theory allows many, but our universe uses one and we don't know which one. I think there's a good candidate for this shape. Many books, rather old, but completely inadmissible in the court of modern science, describe the smallest particle in a way that curiously resembles a string. The string forms a coil, very similar to a wire coil in electromagnets, that revolves almost 3 times around the central axis and then returns back to the entrance. The outer shape is an oblate spheroid and the entire thing is dynamically stable. The coil itself carries electricity, and because of its shape, it produces a magnetic field that streams thru the center. The particle performs rapid gyrations around the central axis - that's probably the same effect as the Lamour precession. There are two types of this particle: one with clockwise direction of the coil and the other with counterclockwise. The string enters and exits the area in a direction perpendicular to all 3 dimensions, so it kind of appears from nowhere. The string itself is made of a finer coil, and that of even finer coil and so on a few times. If the 10 dimensions guess is correct, then there are probably 6 or 7 such finer coils. If the entire thing is unrolled, it would form a circle of very large radius. While such a particle, that probably corresponds to the electron, has enormously complex internal structure, it's still a fundamental particle of 3d world, because cutting the string in any place makes it recombine into numerous tiny coiled strings, but all of them freely float along the 4th dimension and barely interact with the 3d particles, so they become kind of background noise of unknown origin. The magnetic stream that flows thru the central axis of each 3d particle is made of these tiny 4d particles, and those probably replicate the entire arrangement at a smaller scale, so there probably are even smaller 5d coiled strings and so on. Like I've said, this kind of description is inadmissible in science, but it's ok to "guess" it and invent a plausible explanation that this shape minimizes some weird functional in a hilbert space of the strings theory.
- pfdietz 6y ago
  > but our universe uses one Oh really.
- AnimalMuppet 6y ago
  Yeah... um... "many books, rather old, but completely inadmissible in the court of modern science" seems like an improbable place to expect to have any accurate insight into the actual fundamental nature of fundamental particles. Even if they contain something that, if you squint hard enough, looks like a string, that's no reason to suppose that reality actually looks like that. (But I suspect that you're inclined to accept those books for other reasons, and therefore to accept them as also accurate about physics. I suppose a starting point is where you find it, but you should forgive the rest of us when we remain unconvinced that it is likely to be a useful starting point.)
mensetmanusman 6y ago
I wonder if future historians will look back at this time in physics and use the chemistry analogy of phlogiston. https://en.m.wikipedia.org/wiki/Phlogiston_theory https://en.m.wikipedia.org/wiki/Phlogiston_theory Then, as now, there was a large body of entrenched individuals who would not budge until some ingenious experiments by the British and French (et al.) to entirely destroy the theory.
- soneca 6y ago
  A falsifiable theory that led to a useful discovery (of oxygen, according to the Wikipedia article) seems nothing like string theory.
  - pfdietz 6y ago
    A closer match is the Victorian era vortex theory of the atom. https://www.academia.edu/4084776/The_Vortex_Atom_A_Victorian_Theory_of_Everything https://www.academia.edu/4084776/The_Vortex_Atom_A_Victorian...
- Gibbon1 6y ago
  I think of the closing to an essay by Martin Gardner on once mainstream scientific theories, eugenics, Freudism, etc. Which is when evidence is weak then scientific theory tends to exactly match scientists cultural biases. With string theory there is no evidence to work off. To me it feels like with nothing better to do everyone in the field is just trying to out math everyone else.
  - jjgreen 6y ago
    Using "math" as an abbreviation for the noun mathematics always grates a little for us Brits (not that we'd say anything), but as a verb it totally works, I math, you math, he/she maths ...
    - rxhernandez 6y ago
      And yet, despite all that annoyance for the ways Americans use the language, a significant number of French derived words are butchered on that side of the pond (e.g. lieutenant).
narrator 6y ago
In computer science, researchers who had spent decades working on feature engineering for images got completely blown out of the water by deep learning. All those decades of papers would never get another cite. Everyone moved on. String theory doesn't actually do anything though, so there's no way to say it's better or worse than anything else. It's like someone saying they're working on solving the halting problem or something and eventually they'll get there and they've been working on it for 20 years without any code that actually works. At some point, you just have to give up and do something else. They keep getting grants to work on this stuff though for some reason. Someone needs to interview the people who are giving out string theory grants and ask them why the heck they are still giving these people money.
- posterboy 6y ago
  > At some point, you just have to give up and do something else. Imaginably, given the field's topics, they think in different dimensions than on a 20 year scale.
- crdrost 6y ago
  There might still be some value in it. I think people will use tools like AdS/CFT correspondence for a while. And it is worth remembering that in terms of actual dollars, fundamental physics research is not that big of a spend. Like, part of the reason why these articles are important, is that the pie is so small to start with. So I don't worry too much about the string theory grant money, if anything I would not mind the absolute dollar amount going up if the relative fraction decreased with it. The one thing that kind of irks me is this Kaku book “The God Equation.” I have only seen one equation that is so universally applicable that it could deserve that title, and even then I would be hesitant about that because it might give people the wrong impression. (It is the transport equation—it keeps appearing and appearing, a bunch of other equations are special cases of it, it is involved in one of the million-dollar Clay Mathematics prizes so there is clearly something hard/intractable about it, and it has a term which refers to creation and destruction. It says, a box flows downstream, the time rate of change of stuff in the box is equal to the flow J of stuff through the walls of the box plus the rate Φ of stuff being created/destroyed in the fluid. Or, ∂ρ/∂t + (v · ∇) ρ = - ∇ · J + Φ.)
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lifeisstillgood 6y ago
1. Don't try too hard to make science funding more efficient / market lead or whatever - just fund more - double the science budget tomorrow And again every five years for a generation. We are about to go through a societal refactoring with solar / electric / digital / climate change hitting at once. Spending a few quid to help out the fundamentals won't hurt anyone. 2. The above might upset people but string theory is a good example - partly yes people are held hostage by funding (much like it's hard to avoid being typecast as an actor). But the solution to that is to fund lots more (experimental) movies, not to hope studio heads can pick better winners. I am perfectly happy for a slice of my tax dollar to go on someone thinking about Pram theory (#) for a decade simply because we have no idea whatsoever how to tackle the big ones in physics, so spray and pray is going to be a lot better than most other options. (#) Red Dwarf episode. worth watching episode just for this joke.
- kestonis 6y ago
  Could not agree more. If you see into most big discoveries, fundamentals were laid 50-70 years ago. F.e. math for string theory (twistor space) was in 1960s while theory itself gained traction in 1990s. Todays the new math developed under premise of string theory might be fundamental for future theories coming 50 year later, even if string theory would be proven wrong
- read_if_gay_ 6y ago
  I would agree with funding more science, but you'll need some hoops to jump through or anyone can just come in and grab free money to "do research" with. I think you will necessarily end up not too far from where we are now because of that.
  - intended 6y ago
    sure go for it. If you have a country rewarding intellectual effort, that’s a good country to be a part of. I’m betting that there will be more smart people trying more smart things that will end up positive than not. I mean we are on a hackers and startups forum - it’s the fundamental premise of a majority of people visiting this site. Honestly this seems like an issues of not having testable hypotheses. I’d love to see how it gets to a testable state.
pontus 6y ago
Disclaimer: My background is in string theory. I've spent a lot of time thinking about this subject (in fact, I studied string theory at Columbia which is where Peter Woit is). The main issue that people have with string theory is the lack of testability / falsifiability. I think there's definitely some issues there, but I think blaming string theory is not quite right. There are two reasons why string theory is tough to test. One of them, and the most obvious one, is that the energy scale where the strings exist is super high (likely at or near the Planck scale). This means that if we wanted to detect the direct signatures of strings, we'd have to create an experiment that is sensitive to these energy scales. This seems to be completely infeasible (people talk about particle colliders having to be the size of our solar system etc.) Now, interestingly this is not actually only a problem with string theory but rather with any theory of quantum gravity. This is because the fundamental scale of a theory is usually determined by combining its fundamental constants in some way as to produce an energy scale, and any theory of quantum gravity must somehow contain Planck's constant, Newton's constant of gravitation, and the speed of light. Taking these together gives you the Planck scale. So, in other words if the reason you don't want to study string theory is that it only is testable at the Planck scale, then what you're really saying is that you don't think we should study any theory of quantum gravity. This is, I think, way to extreme of a position. Now, interestingly, string theory is actually more than a theory of gravity, so unlike something like e.g. loop quantum gravity which is only a theory of gravity, it's conceivable that string theory somehow within it contains information that "trickles down" to lower energies and thus could potentially be testable at something like the LHC. This leads me to the second reason why string theory is very difficult to test. It turns out that the equations of string theory are more-or-less unique at high energies but that as you start lowering the energy at which you probe the theory, multiple distinct solutions emerge. These solutions turn out to have a very nice physical interpretation: they are the different ways in which we can compactify the extra dimensions of string theory. Regardless of this physical interpretation, the fact remains that there are many many distinct solutions of string theory at low energies, and in order to make predictions that are falsifiable, we need to know which of these solutions we're living in. This is where the crux of the problem lies. It turns out that there are so many solutions of string theory that we cannot even in principle go through them one at a time to see if they're feasible (people throw around the number 10^500). Now, it turns out that the real problem is not actually in the number of distinct solutions to string theory (~10^500), but rather in the way their structure is poorly understood. In fact, any theory of physics contains an infinite number of theories within it. For example, consider the mass of the electron as a free parameter. Until I tell you what the mass is, you can't make a complete prediction for what the energy levels in Hydrogen are. In fact, you could argue that since the mass of the electron is a real number, there are in fact an infinite number of predictions to the energy levels. A bit sarcastically you could then say that at least string theory has "only" 10^500 different theories within it, unlike traditional physics that has this continuous infinite set of theories. The distinction between these two cases is then that for traditional theories, we can go the other way. If we measure the energy levels of Hydrogen, we can infer the mass of the electron. Then, knowing the mass of the electron, we can make other predictions. It's this last step that's currently missing in string theory. Currently we only know how to move in one direction: give me the solution you're talking about and I might be able to make predictions, but give me observational data and I can't work backwards to determine which solution I'm in. It's almost like a one-way hash. I would say that this last objection is a roadblock that we're currently facing, and it's not perfectly clear that it's not solvable, nor is it clear that it is. I think that until we solve this problem, string theory will be stuck and people will be pointing fingers at the theory calling it a fool's errand. I personally think this criticism is misguided. The upshot of this is that most people who work on string theory work in areas that are not plagued by this bifurcation to low energies. For example, you can use string theory to study the structure and behavior of black holes and holography, something called AdS/CFT, an area that has been incredibly successful.
TheMagicHorsey 6y ago
Public grant making is a very political process. People imagine there is an apolitical body that makes grants to physicists based on the merits of their work ... but that's not the case. In any resource allocation scheme where the grantors have no skin in the game, politics and cronyism will dominate in the long term. That's probably what's happened here. String theorists get grants not because string theory produces practical results, but because there is now a network of string theorists and sympathizers in charge of the institutions that control professorships and grant making. That's why resource allocation should be left to those with skin in the game. A market is one mechanism for forcing allocators to expose themselves to the downsides of bad investments ... but there are other mechanisms if people have an allergy to markets.
kkwteh 6y ago
It looks like Planck's Principle is in effect here. To paraphrase, "Science progresses one funeral at a time."
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zinclozenge 6y ago
Yes, it's true that string theory hasn't panned out in the same way as general relativity or the standard model, but it really bothers me when people criticize it without even tacit acknowledgement of the fruitful discoveries that came out of the research that has been applied to other fields. The AdS/CFT correspondence alone is worth the effort that was put in, not to mention mirror symmetry in algebraic geometry and everything that was discovered about Calabi-Yau manifolds. String theory research isn't directly useful, but other fields of physics and mathematics reap the benefits.
interestica 6y ago
I would love to see a series of "20 years later" posts on a bunch of different fields. Where was the field at in 2000, where did they think they were going, where are they now? Related: what are the fields that did fade or have a major change where they may not even be around now.
- rablackburn 6y ago
  You and me both. It's hard as a layman to keep track of what's happening in real-time. I love going back to things in ~1-decade intervals and seeing lists and articles etc showing what's happened "in-review". Usually those kinds of overviews are limited to things like media genres, not fields of science. (eg best video games of the last 10 years, best movies and how they changed the industry etc). Something a bit more academic would be nice...
  - sgt101 6y ago
    This is an interesting sub thread, a lot of the threads here seem to have the wrong idea about how funding really works. I've been involved in DARPA programs and EU programs and sat on national committees allocating research funding an I think that there is a much more progressive and critical stance than folks portray here. A good example is the Semantic Web movement - big excitement 20 years ago, big funding, big community... no results really....then no funding, community switches to other things real fast. There is a lot of griping about this in Comp Sci with people from the Semantic Web groups rightly saying that the funding bodies bought the hype and misallocated the funds on short term silly projects and that if just a fraction of the money had been provided in a structured and long term way a great deal more would have got done. But what is really clear is that there is no real institutional effort to do what you suggest above - folks are not really tracking how well the funding system is working or what has worked and what hasn't. All of the reviews that I have seen are forward looking and driven by science insight, administrative change seems to be done by MBA fashion - or inertia.
boxmonster 6y ago
A long time ago in a galaxy far away I entered U.C. Berkeley as a physics major. Then I dropped acid and became very interested in consciousness, but didn't see that being taught in the physics track, so I dropped it. Now I see that physics is coming around to talking about consciousness. I don't know why they stopped, because I learned later that early 2oth century physicists did talk about it. Max Planck among others. Materialism reigns supreme and I don't know why. No one has to start being a theist when they stop being a materialist. I regard consciousness as fundamental. I regard matter as derivative from consciousness. We cannot get behind consciousness. Everything that we talk about, everything that we regard as existing, postulates consciousness ― Max Planck
- ryan93 6y ago
  You clearly wouldn’t have made it as a physicist.
- renox 6y ago
  That's funny: your post talk has exactly the same problems as string theory: untestable predictions. How are you going to do experiments which test whether 'consciouness is fundamental' or not?
  - boxmonster 6y ago
    As I said, physicists thought about it 100 years ago and then the atomic age came along and physicists didn't pursue consciousness as an area of interest. That's been changing recently. Some catching up must be done. As you point out, tests do not exist yet. It doesn't matter if you give up on it. It's being pursued. I think it's an interesting consideration.
unnouinceput 6y ago
I like String Theory. It's a beautiful theory that's striking all the right chords within me. Lemme paraphrase the great Arthur C. Clarke about this. We are fish in water. And some time fishes do jump out of the water. And sometime fishes, while jumping out of the water are seeing fires on land. That's String Theory for me - it's a fire on land that we get a glimpse of it and can't quite make what it is. And until we will not walk on land and make fire ourselves we'll never fully understand its potential. 20 years is nothing in this regard. My 2 cents.
ncmncm 6y ago
It may be true that, "Lubos Motl is still arguing that string theory is the language in which God wrote the universe"; but it has been several years since I last encountered any text he wrote. So, that seems like progress, of sorts. I gather that Alzheimer's research is still almost exclusively about amyloid plaques and tau tangles, despite absolutely negative results and disastrous drug trials for decades. And, of course, magnetic confinement fusion is still 20 - 30 years off, and always will be.
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arbirk 6y ago
There are lots of examples in physics of math solutions leading to discoveries. On the plus side string theory is a tool that makes it possible to derive conjectures. One day we will find a testable prediction..
wazoox 6y ago
Incidentally I've just read the book "Lost in Math" by Sabine Hossenfelder, and it really goes down into the problems of modern science, its funding, its "publish or perish", its fashions... A really excellent (and quite funny, too) book.
swyx 6y ago
I wonder if a similar moment of reckoning will ever come for modern macroeconomics. I remember working on differential equations on the economy one night and having the sudden insight that the data was far too skimpy and uncontrolled to be at all pretending to do science. and yet there I was going through the motions of doing math on the economy. ditto, of course, goes to holding accountable the economic beliefs of politicians and talking heads of all persuasion. the people conscious of how much we don't know get drowned out by the people who don't care.

412 points by jjgreen 6y ago

> Almost exactly twenty years ago I started writing a short article about the problems with string theory. [...] The piece was done in a week or two, after which I sent it around to a group of physicists to ask for comments. The reaction was mostly positive, although at least one well-known theorist told me that publicly challenging string theorists in this way would be counter-productive. I like to know the subject before I wander off HN following a nondescript title...

throwaway98797 6y ago
Domain name should give a clue. Plus, a little bit of randomness is the spice of life.
- CyberDildonics 6y ago
  Don't rationalize clickbait. This site doesn't allow comments without substance, but for some reason link titles don't have the same standards.
  - hyperpape 6y ago
    The title wasn't written for you, but that doesn't make it clickbait. That's true even though it's not a great title. The author is a physicist/computer scientist writing on his personal blog. He is writing about some of his own work, 20 years later, and his likely audience probably has context about that work, or will be linked from somewhere that provides that context. The fact that you and I stumbled upon it from a decontextualized aggregator is a bug.
    - CyberDildonics 6y ago
      It wouldn't be a bug if there was more information than "20 years later"
    - fireattack 6y ago
      Totally unrelated, but why is he in Math department instead of Physics?
      - cambalache 6y ago
        Peter Woit(the author) is a lecturer in the department of mathematics at Columbia University. He is kind of a black sheep in the high-energy physics world. He has a PhD in physics from Harvard, so he certainly has the credentials but his academic career stalled/never took off, so after some post-docs he took a job at Columbia teaching mathematics and maintaining the computer network of the department. A fact that has not passed unnoticed by his "enemies"(many string theorists),so they use that to mock him and dismiss his not entirely unreasonable criticism of ST. That shows you that eminent physicists can be as tribalistic, petty and emotional as a stereotypical 14 year old girl.
  - segfaultbuserr 6y ago
    No, clickbaits are usually disallowed in the title. The rule is use original title, most of the time it's indeed an anti-clickbait rule (although some false negatives are unavoidable). > Please don't do things to make titles stand out, like using uppercase or exclamation points, or saying how great an article is. It's implicit in submitting something that you think it's important. > [...] Please use the original title, unless it is misleading or linkbait; don't editorialize. My personal observation, there are three types of bad titles. 1. Clickbait titles editorialized by a submitter to make everyone know how great/important the article is. 2. Clickbait titles from the source. 3. Non-descriptive title from the source. 60% of the bad titles are Type-1 title from the submitters (as everyone who ever browsed Reddit would know). To prevent such behaviors, the "use original title" rule is implemented on Hacker News. 30% of the titles are Type-2 title. On Hacker News, if many readers loudly criticize that the original title is misleading, eventually a moderator will correct it manually. 10% of the titles are Type-3 title, non-descriptive title that contain little information, but it's neither misleading or clickbait. On Hacker News, usually, nothing happens. This article is one of them. Also, any attempt to change the title could be seen as Type-1 title editorialization, so the original title remains. So sometimes, even after the title has been changed by the submitter to be more descriptive, it could be reverted back to the original, non-descriptive one. > This site doesn't allow comments without substance, but for some reason link titles don't have the same standards. Whenever people compliant that Hacker News allows non-descriptive titles, please consider the fact that "use the original title" does more good than harm in general with a false negative rate of only 10%, which is a small price to pay.
- AnimalMuppet 6y ago
  The domain name doesn't give me a clue that it's about physics, instead of, say, sociology or something.
  - throwaway98797 6y ago
    Okay princess.
raldi 6y ago
Thank you. I came to the comments hoping for exactly this.
jjgreen 6y ago
Sorry about that, just following the submission guidelines [1] but should have left an explanatory initial comment I guess ... [1] https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
- jagged-chisel 6y ago
  Hey, no worries. The title is definitely not your fault. :)
- Exmoor 6y ago
  I almost certainly would have never clicked on an article about String Theory, even if it was trending at #1, but because of the vague title I did and was happily surprised to learn something about the world of physics and physics researchers.
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idlewords 6y ago
Thoughts and prayers to you in this challenging time.

hardtke 6y ago

One of the biggest problems in science (in general) is that your reputation and therefore funding is highly tied to a particular subfield. Everyone in a subfield knows each other and gives positive grant reviews and external tenure letters to other practitioners. If you try to move on to new areas of research, your reputation and funding are gone. The outcome is that areas of research interest become quasi-permanent, even when they are no longer interesting. I talk to the people today that still work in my specialty of nuclear physics (relativistic heavy ion physics) and I'm shocked at how little intellectual progress has been made. At the risk of offending people it's time to give up and declare victory, but the consequences would be dire (hundreds of professors all over the world without grants).

marta_morena_9 6y ago
If there is funding, there is apparently a need for research. The solution is never for the individuals to induce change. This doesn't work for consumers (i.e. you can't say "If everyone stops buying plastic bags, we do something for the environment", because well, nobody cares... You have to make selling plastic bags either illegal or add a significant surcharge that causes consumers to avoid them for reasons that actually affect them, like "too expensive") And it doesn't work for anything else either. As long as there is funding, this will go on. The "solution" is to stop funding, but apparently since funding is still flowing, someone still values the research. So what is even the problem? No progress has been made? Well, if funding is still there, whoever funds this seems to be beyond happy with the progress. This is a non-issue.
- xapata 6y ago
  Perhaps the issue is that the funding agency is not sophisticated enough to realize that there's no value, or more value elsewhere?
  - wadkar 6y ago
    OR perhaps the issue that the same people who are in the clique of the said field are also evaluating the research proposals. So the funding doesn’t run dry? Not that that’s a good or bad thing. You wouldn’t want a “non-expert” to evaluate the proposal. And perhaps a tapering of the funding is better indicator of interest/progress of the field?

whatshisface 6y ago

What is there around to replace string theory with? I predict that if there ever is a viable alternative available with even 0.001% more evidence supporting it, strings will vanish in a day. Presently all other approaches to quantum gravity are in a less developed state and make even fewer predictions.

Iwan-Zotow 6y ago
Fewer than 0? How come?
- whatshisface 6y ago
  String theory at least predicts gravity in three dimensions. Other approaches to quantum gravity are not even far enough along to do that - it was an immense and relatively recent accomplishment to have LQG on a circle.
  - guscost 6y ago
    String theory has not made predictions that are in any sense meaningful to science. “Confirmations should count only if they are the result of risky predictions; that is to say, if, unenlightened by the theory in question, we should have expected an event which was incompatible with the theory--an event which would have refuted the theory.” - Popper
    - whatshisface 6y ago
      >String theory has not made predictions that are in any sense meaningful to science. You're welcome to set the bar of meaningful at any level you like; such a statement cannot in principle be disagreed with. However the point stands that string theory has made more accurate empirical predictions than any other theory of quantum gravity. That doesn't mean no other theory of quantum gravity will ever beat it, just that the focus on string theory among people and funders who are precomitted to studying quantum gravity is rational.

l0b0 6y ago

I can't help but feel cynical about this piece: 1. 20 years ago the author wrote a paper asserting that string theory was a fruitless field of study. 2. The paper is written in a confrontational and snarky tone, for example: "The theory has been spectacularly successful on one front, that of public relations." Not a way to build bridges. 3. The author seems bitter that the paper wasn't accepted into Physics Today, and that the suggested rewriting into a letter to the editor did not result in publication either. 4. The author is sticking to their guns. No matter how well-founded the idea that string theory is a dead end, this isn't likely to improve things.

meowkit 6y ago
Hard disagree on #3. He seems annoyed that he didn’t get any followup, which is totally warranted.
- l0b0 6y ago
  I assume a publication like Physics Today gets a lot of submissions, and that probably the majority of them are rejected. Maybe there would've been a better chance of acceptance if the article (and presumably also the letter to the editor) wasn't so confrontational.
  - cycomanic 6y ago
    Physics today is not a scientific journal. I highly doubt that they get a lot of submissions. In my experience with similar publications in a different subfield it's typically more that the journalists/editors at those magazines think that some topic is interesting and talk to some of the more famous researchers in the field to write an article. Sometimes it's also a bit the other way around and the researchers suggest articles to editors they know. Not to publish a letter to the editor seems a very strange decision, these are very short letters and sometimes really cover some quite niche topics. Also not getting back to the author after asking him to rewrite in a different format is just bad form.
hitekker 6y ago
The scientist saw BS, he called BS, and then 20 years later, the field he criticized turned out to be mostly BS. If you're offended by the audacity of scientists criticizing pseudoscience, you may want to read about the concept of "polemics". It's an acceptable, longstanding form of rhetoric for when a respected figure publicly disagrees with a direction of another group of people. https://en.wikipedia.org/wiki/Polemic https://en.wikipedia.org/wiki/Polemic Incidentally, the author even noted his article was a polemic in the original abstract https://arxiv.org/abs/physics/0102051 https://arxiv.org/abs/physics/0102051

dilippkumar 6y ago

Is there a popular science book that begins with Noether’s theorem (along with some biographical details and historical context in which her theorem must be understood) and traces developments from there down to the Standard Model and talks about what the standard model doesn’t solve and why new theories are interesting? Preferably a book that doesn’t go off into the deep end with alternate realities and dead/alive cats in boxes. I read Higgs by Jim Baggot, it did a good job of providing an overview - however I would like something that goes into a little more detail while still being a popular science book.

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whatshisface 6y ago
I don't understand how you could imagine having a discussion about "what the standard model doesn’t solve and why new theories are interesting," that wasn't in the language of quantum mechanics, which the dead/alive cats in boxes thing would be an elementary first step of learning. Field theory is way farther off the deep end than the measurement of a two-state system.
- centimeter 6y ago
  There are several languages with which you can discuss the standard model, particularly Group Theory, which I don't think require much familiarity with the details of QM. I assume this is what the GP is talking about given his mention of Noether currents. I say this as someone who is quite familiar with QM, so it's very possible I'm just neglecting to consider all the implicit context I'm working with.
  - whatshisface 6y ago
    Group theory has applications in QM, but you can't go from the standard model to experimental results through group theory alone. To do that, you need to understand all of the physics concepts leading up to it. Even knowing what a conserved quantity is involves some of that implicit context you're talking about.

Scene_Cast2 6y ago

I find that in big organizations, this is is a very frequent pattern. There is a commonly accepted approach that is obviously wrong to a subset of people. However, the people that are able to see the "wrongness" either don't have the political skills to accelerate a mental shift for the entire organization, or they choose to apply their limited "political leverage" to a different (often smaller and more tractable) problem instead.

jariel 6y ago

The key quote: "The tribalistic sociology that has led to a large group of people calling themselves “string theorists” when what they do has nothing to do with string theory is also something I would have thought impossible." It's my personal bias but I see every group this way. As someone intrigued by 'cults' early in life, I've come to see that all groups exhibit quite a lot of in/out group behaviour, the weird things is when it happens among those most socially unaware people (often science) - combined with a highly objective discipline (again science) ... people are just unwilling to accept that social artifacts can dominate their sphere. Now, the existential issue of the fact that their 'entire worldview' and 'life-long work' is tied up in something, delusions can become very strongly internalized. String theory is at least as interesting for the 'sociology' part as it is the 'string' part. String theory, and the 'reproducability problem' has kind of shaken my faith in science. I grew up really 'believing' in Science, I view it much more differently these days - including those who have this unassailable faith in it as likely being a little deluded themselves.

pdonis 6y ago
> It's my personal bias but I see every group this way. I have the same "bias". What people seem to forget is that the scientific method was supposed to be a way to develop theories that made good predictions in spite of the fact that humans, both individually and in groups, are unreliable and do all sorts of crazy things for all sorts of crazy reasons. Calling oneself a "scientist" or having an advanced degree does not make one less susceptible to that. One has to set up institutions that will harness the craziness of humans and human groups in a direction that, on average and over the long term, is productive. But what most people call "science" today is not such an institution. For example, the real message of the "replication crisis" is that most of what the average person is told is "science" is actually nothing of the sort. A sane institution of science would never have labelled that stuff as "science" in the first place; it would have said "sorry, we're still working on this, no results yet". And a lot of times it would say that and there never would be any results, and science would say "no results from this line of research; that's to be expected since many lines of research that initially look promising don't pan out".
- 6y ago

frongpik 6y ago

IIRC, one big problem of the strings theory was the shape of those strings: the theory allows many, but our universe uses one and we don't know which one. I think there's a good candidate for this shape. Many books, rather old, but completely inadmissible in the court of modern science, describe the smallest particle in a way that curiously resembles a string. The string forms a coil, very similar to a wire coil in electromagnets, that revolves almost 3 times around the central axis and then returns back to the entrance. The outer shape is an oblate spheroid and the entire thing is dynamically stable. The coil itself carries electricity, and because of its shape, it produces a magnetic field that streams thru the center. The particle performs rapid gyrations around the central axis - that's probably the same effect as the Lamour precession. There are two types of this particle: one with clockwise direction of the coil and the other with counterclockwise. The string enters and exits the area in a direction perpendicular to all 3 dimensions, so it kind of appears from nowhere. The string itself is made of a finer coil, and that of even finer coil and so on a few times. If the 10 dimensions guess is correct, then there are probably 6 or 7 such finer coils. If the entire thing is unrolled, it would form a circle of very large radius. While such a particle, that probably corresponds to the electron, has enormously complex internal structure, it's still a fundamental particle of 3d world, because cutting the string in any place makes it recombine into numerous tiny coiled strings, but all of them freely float along the 4th dimension and barely interact with the 3d particles, so they become kind of background noise of unknown origin. The magnetic stream that flows thru the central axis of each 3d particle is made of these tiny 4d particles, and those probably replicate the entire arrangement at a smaller scale, so there probably are even smaller 5d coiled strings and so on. Like I've said, this kind of description is inadmissible in science, but it's ok to "guess" it and invent a plausible explanation that this shape minimizes some weird functional in a hilbert space of the strings theory.

pfdietz 6y ago
> but our universe uses one Oh really.
AnimalMuppet 6y ago
Yeah... um... "many books, rather old, but completely inadmissible in the court of modern science" seems like an improbable place to expect to have any accurate insight into the actual fundamental nature of fundamental particles. Even if they contain something that, if you squint hard enough, looks like a string, that's no reason to suppose that reality actually looks like that. (But I suspect that you're inclined to accept those books for other reasons, and therefore to accept them as also accurate about physics. I suppose a starting point is where you find it, but you should forgive the rest of us when we remain unconvinced that it is likely to be a useful starting point.)

mensetmanusman 6y ago

I wonder if future historians will look back at this time in physics and use the chemistry analogy of phlogiston. https://en.m.wikipedia.org/wiki/Phlogiston_theory https://en.m.wikipedia.org/wiki/Phlogiston_theory Then, as now, there was a large body of entrenched individuals who would not budge until some ingenious experiments by the British and French (et al.) to entirely destroy the theory.

soneca 6y ago
A falsifiable theory that led to a useful discovery (of oxygen, according to the Wikipedia article) seems nothing like string theory.
- pfdietz 6y ago
  A closer match is the Victorian era vortex theory of the atom. https://www.academia.edu/4084776/The_Vortex_Atom_A_Victorian_Theory_of_Everything https://www.academia.edu/4084776/The_Vortex_Atom_A_Victorian...
Gibbon1 6y ago
I think of the closing to an essay by Martin Gardner on once mainstream scientific theories, eugenics, Freudism, etc. Which is when evidence is weak then scientific theory tends to exactly match scientists cultural biases. With string theory there is no evidence to work off. To me it feels like with nothing better to do everyone in the field is just trying to out math everyone else.
- jjgreen 6y ago
  Using "math" as an abbreviation for the noun mathematics always grates a little for us Brits (not that we'd say anything), but as a verb it totally works, I math, you math, he/she maths ...
  - rxhernandez 6y ago
    And yet, despite all that annoyance for the ways Americans use the language, a significant number of French derived words are butchered on that side of the pond (e.g. lieutenant).

narrator 6y ago

In computer science, researchers who had spent decades working on feature engineering for images got completely blown out of the water by deep learning. All those decades of papers would never get another cite. Everyone moved on. String theory doesn't actually do anything though, so there's no way to say it's better or worse than anything else. It's like someone saying they're working on solving the halting problem or something and eventually they'll get there and they've been working on it for 20 years without any code that actually works. At some point, you just have to give up and do something else. They keep getting grants to work on this stuff though for some reason. Someone needs to interview the people who are giving out string theory grants and ask them why the heck they are still giving these people money.

posterboy 6y ago
> At some point, you just have to give up and do something else. Imaginably, given the field's topics, they think in different dimensions than on a 20 year scale.
crdrost 6y ago
There might still be some value in it. I think people will use tools like AdS/CFT correspondence for a while. And it is worth remembering that in terms of actual dollars, fundamental physics research is not that big of a spend. Like, part of the reason why these articles are important, is that the pie is so small to start with. So I don't worry too much about the string theory grant money, if anything I would not mind the absolute dollar amount going up if the relative fraction decreased with it. The one thing that kind of irks me is this Kaku book “The God Equation.” I have only seen one equation that is so universally applicable that it could deserve that title, and even then I would be hesitant about that because it might give people the wrong impression. (It is the transport equation—it keeps appearing and appearing, a bunch of other equations are special cases of it, it is involved in one of the million-dollar Clay Mathematics prizes so there is clearly something hard/intractable about it, and it has a term which refers to creation and destruction. It says, a box flows downstream, the time rate of change of stuff in the box is equal to the flow J of stuff through the walls of the box plus the rate Φ of stuff being created/destroyed in the fluid. Or, ∂ρ/∂t + (v · ∇) ρ = - ∇ · J + Φ.)

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lifeisstillgood 6y ago

1. Don't try too hard to make science funding more efficient / market lead or whatever - just fund more - double the science budget tomorrow And again every five years for a generation. We are about to go through a societal refactoring with solar / electric / digital / climate change hitting at once. Spending a few quid to help out the fundamentals won't hurt anyone. 2. The above might upset people but string theory is a good example - partly yes people are held hostage by funding (much like it's hard to avoid being typecast as an actor). But the solution to that is to fund lots more (experimental) movies, not to hope studio heads can pick better winners. I am perfectly happy for a slice of my tax dollar to go on someone thinking about Pram theory (#) for a decade simply because we have no idea whatsoever how to tackle the big ones in physics, so spray and pray is going to be a lot better than most other options. (#) Red Dwarf episode. worth watching episode just for this joke.

kestonis 6y ago
Could not agree more. If you see into most big discoveries, fundamentals were laid 50-70 years ago. F.e. math for string theory (twistor space) was in 1960s while theory itself gained traction in 1990s. Todays the new math developed under premise of string theory might be fundamental for future theories coming 50 year later, even if string theory would be proven wrong
read_if_gay_ 6y ago
I would agree with funding more science, but you'll need some hoops to jump through or anyone can just come in and grab free money to "do research" with. I think you will necessarily end up not too far from where we are now because of that.
- intended 6y ago
  sure go for it. If you have a country rewarding intellectual effort, that’s a good country to be a part of. I’m betting that there will be more smart people trying more smart things that will end up positive than not. I mean we are on a hackers and startups forum - it’s the fundamental premise of a majority of people visiting this site. Honestly this seems like an issues of not having testable hypotheses. I’d love to see how it gets to a testable state.

pontus 6y ago

Disclaimer: My background is in string theory. I've spent a lot of time thinking about this subject (in fact, I studied string theory at Columbia which is where Peter Woit is). The main issue that people have with string theory is the lack of testability / falsifiability. I think there's definitely some issues there, but I think blaming string theory is not quite right. There are two reasons why string theory is tough to test. One of them, and the most obvious one, is that the energy scale where the strings exist is super high (likely at or near the Planck scale). This means that if we wanted to detect the direct signatures of strings, we'd have to create an experiment that is sensitive to these energy scales. This seems to be completely infeasible (people talk about particle colliders having to be the size of our solar system etc.) Now, interestingly this is not actually only a problem with string theory but rather with any theory of quantum gravity. This is because the fundamental scale of a theory is usually determined by combining its fundamental constants in some way as to produce an energy scale, and any theory of quantum gravity must somehow contain Planck's constant, Newton's constant of gravitation, and the speed of light. Taking these together gives you the Planck scale. So, in other words if the reason you don't want to study string theory is that it only is testable at the Planck scale, then what you're really saying is that you don't think we should study any theory of quantum gravity. This is, I think, way to extreme of a position. Now, interestingly, string theory is actually more than a theory of gravity, so unlike something like e.g. loop quantum gravity which is only a theory of gravity, it's conceivable that string theory somehow within it contains information that "trickles down" to lower energies and thus could potentially be testable at something like the LHC. This leads me to the second reason why string theory is very difficult to test. It turns out that the equations of string theory are more-or-less unique at high energies but that as you start lowering the energy at which you probe the theory, multiple distinct solutions emerge. These solutions turn out to have a very nice physical interpretation: they are the different ways in which we can compactify the extra dimensions of string theory. Regardless of this physical interpretation, the fact remains that there are many many distinct solutions of string theory at low energies, and in order to make predictions that are falsifiable, we need to know which of these solutions we're living in. This is where the crux of the problem lies. It turns out that there are so many solutions of string theory that we cannot even in principle go through them one at a time to see if they're feasible (people throw around the number 10^500). Now, it turns out that the real problem is not actually in the number of distinct solutions to string theory (~10^500), but rather in the way their structure is poorly understood. In fact, any theory of physics contains an infinite number of theories within it. For example, consider the mass of the electron as a free parameter. Until I tell you what the mass is, you can't make a complete prediction for what the energy levels in Hydrogen are. In fact, you could argue that since the mass of the electron is a real number, there are in fact an infinite number of predictions to the energy levels. A bit sarcastically you could then say that at least string theory has "only" 10^500 different theories within it, unlike traditional physics that has this continuous infinite set of theories. The distinction between these two cases is then that for traditional theories, we can go the other way. If we measure the energy levels of Hydrogen, we can infer the mass of the electron. Then, knowing the mass of the electron, we can make other predictions. It's this last step that's currently missing in string theory. Currently we only know how to move in one direction: give me the solution you're talking about and I might be able to make predictions, but give me observational data and I can't work backwards to determine which solution I'm in. It's almost like a one-way hash. I would say that this last objection is a roadblock that we're currently facing, and it's not perfectly clear that it's not solvable, nor is it clear that it is. I think that until we solve this problem, string theory will be stuck and people will be pointing fingers at the theory calling it a fool's errand. I personally think this criticism is misguided. The upshot of this is that most people who work on string theory work in areas that are not plagued by this bifurcation to low energies. For example, you can use string theory to study the structure and behavior of black holes and holography, something called AdS/CFT, an area that has been incredibly successful.

TheMagicHorsey 6y ago

Public grant making is a very political process. People imagine there is an apolitical body that makes grants to physicists based on the merits of their work ... but that's not the case. In any resource allocation scheme where the grantors have no skin in the game, politics and cronyism will dominate in the long term. That's probably what's happened here. String theorists get grants not because string theory produces practical results, but because there is now a network of string theorists and sympathizers in charge of the institutions that control professorships and grant making. That's why resource allocation should be left to those with skin in the game. A market is one mechanism for forcing allocators to expose themselves to the downsides of bad investments ... but there are other mechanisms if people have an allergy to markets.

kkwteh 6y ago

It looks like Planck's Principle is in effect here. To paraphrase, "Science progresses one funeral at a time."

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zinclozenge 6y ago

Yes, it's true that string theory hasn't panned out in the same way as general relativity or the standard model, but it really bothers me when people criticize it without even tacit acknowledgement of the fruitful discoveries that came out of the research that has been applied to other fields. The AdS/CFT correspondence alone is worth the effort that was put in, not to mention mirror symmetry in algebraic geometry and everything that was discovered about Calabi-Yau manifolds. String theory research isn't directly useful, but other fields of physics and mathematics reap the benefits.

interestica 6y ago

I would love to see a series of "20 years later" posts on a bunch of different fields. Where was the field at in 2000, where did they think they were going, where are they now? Related: what are the fields that did fade or have a major change where they may not even be around now.

rablackburn 6y ago
You and me both. It's hard as a layman to keep track of what's happening in real-time. I love going back to things in ~1-decade intervals and seeing lists and articles etc showing what's happened "in-review". Usually those kinds of overviews are limited to things like media genres, not fields of science. (eg best video games of the last 10 years, best movies and how they changed the industry etc). Something a bit more academic would be nice...
- sgt101 6y ago
  This is an interesting sub thread, a lot of the threads here seem to have the wrong idea about how funding really works. I've been involved in DARPA programs and EU programs and sat on national committees allocating research funding an I think that there is a much more progressive and critical stance than folks portray here. A good example is the Semantic Web movement - big excitement 20 years ago, big funding, big community... no results really....then no funding, community switches to other things real fast. There is a lot of griping about this in Comp Sci with people from the Semantic Web groups rightly saying that the funding bodies bought the hype and misallocated the funds on short term silly projects and that if just a fraction of the money had been provided in a structured and long term way a great deal more would have got done. But what is really clear is that there is no real institutional effort to do what you suggest above - folks are not really tracking how well the funding system is working or what has worked and what hasn't. All of the reviews that I have seen are forward looking and driven by science insight, administrative change seems to be done by MBA fashion - or inertia.

boxmonster 6y ago

A long time ago in a galaxy far away I entered U.C. Berkeley as a physics major. Then I dropped acid and became very interested in consciousness, but didn't see that being taught in the physics track, so I dropped it. Now I see that physics is coming around to talking about consciousness. I don't know why they stopped, because I learned later that early 2oth century physicists did talk about it. Max Planck among others. Materialism reigns supreme and I don't know why. No one has to start being a theist when they stop being a materialist. I regard consciousness as fundamental. I regard matter as derivative from consciousness. We cannot get behind consciousness. Everything that we talk about, everything that we regard as existing, postulates consciousness ― Max Planck

ryan93 6y ago
You clearly wouldn’t have made it as a physicist.
renox 6y ago
That's funny: your post talk has exactly the same problems as string theory: untestable predictions. How are you going to do experiments which test whether 'consciouness is fundamental' or not?
- boxmonster 6y ago
  As I said, physicists thought about it 100 years ago and then the atomic age came along and physicists didn't pursue consciousness as an area of interest. That's been changing recently. Some catching up must be done. As you point out, tests do not exist yet. It doesn't matter if you give up on it. It's being pursued. I think it's an interesting consideration.

unnouinceput 6y ago

I like String Theory. It's a beautiful theory that's striking all the right chords within me. Lemme paraphrase the great Arthur C. Clarke about this. We are fish in water. And some time fishes do jump out of the water. And sometime fishes, while jumping out of the water are seeing fires on land. That's String Theory for me - it's a fire on land that we get a glimpse of it and can't quite make what it is. And until we will not walk on land and make fire ourselves we'll never fully understand its potential. 20 years is nothing in this regard. My 2 cents.

ncmncm 6y ago

It may be true that, "Lubos Motl is still arguing that string theory is the language in which God wrote the universe"; but it has been several years since I last encountered any text he wrote. So, that seems like progress, of sorts. I gather that Alzheimer's research is still almost exclusively about amyloid plaques and tau tangles, despite absolutely negative results and disastrous drug trials for decades. And, of course, magnetic confinement fusion is still 20 - 30 years off, and always will be.

deleted 6y ago

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arbirk 6y ago

There are lots of examples in physics of math solutions leading to discoveries. On the plus side string theory is a tool that makes it possible to derive conjectures. One day we will find a testable prediction..

wazoox 6y ago

Incidentally I've just read the book "Lost in Math" by Sabine Hossenfelder, and it really goes down into the problems of modern science, its funding, its "publish or perish", its fashions... A really excellent (and quite funny, too) book.

swyx 6y ago

I wonder if a similar moment of reckoning will ever come for modern macroeconomics. I remember working on differential equations on the economy one night and having the sudden insight that the data was far too skimpy and uncontrolled to be at all pretending to do science. and yet there I was going through the motions of doing math on the economy. ditto, of course, goes to holding accountable the economic beliefs of politicians and talking heads of all persuasion. the people conscious of how much we don't know get drowned out by the people who don't care.