I would also include Laughlin's theory of the fractional quantum Hall effect. This was a major achievement in theoretical physics in the 1980s and led to the concept of topological order (Wen), which also underlies much of the current research on topological insulators you mentioned in your list. Anyway, it is difficult to remember everything. Nevertheless, your list seems to be pretty much complete to me.
Minor point, but I think you've got the timeline of quantum computing and quantum cryptography backwards. I don't know of any evidence that the idea of a quantum computer was discussed before 1980. Feynman's first talk on the subject was in 1981 and his first paper in 1982. Detusch's start in 1985. There are precursor papers by Benihoff and Manin, but they were published in 1980.
On the other hand, Wiesner's work on conjugate coding from the 70's an obvious precursor to quantum cryptography, and he applied it to a cryptographic task. Admittedly, this was "quantum money" rather than key distribution, but Bennett and Brassard used the same encoding scheme for BB84, and Bennett acknowledges that the conjugate coding idea came from Wiesner.
I think Steve must have meant "theoretical high-energy physics", and I think to count it must be something that has been confirmed by experiment. If that's the case, then I don't see anything on your list that counts.
The only thing I can think of is the relation between the fermion masses and the W mass accounted for using non-commutative geometry. That certainly wasn't known in the 1980s. But arguably it still isn't very well known!
Possibly also the Planck satellite data validates some cosmological models, but I don't know if that counts as an "advancement".
Yes possibly, but you see, that's exactly my point - most of physics is not hep. It annoys me if people aren't able to make this distinction. It's like saying there's no skyscraper in Vienna, consequently architecture must be in a crisis.
Did theoretical physics predict dark matter, dark energy or high temperature superconductivity? Was there much of anything predicted?
The answer to the first question is no. The second is of course open to interpretation, my take is 'not much' - especially when the number of person hours spent on theoretical physics since 1980 is very likely greater than the time spent on all theoretical physics before 1980 - back to Aristotle.
Where are these "stories about a crisis in physics that the media warm up and serve every couple of months"? I see a wall of self congratulatory articles, and only one article from April 2014 on a crisis in one field, supersymmetry.
I'm sure there have been many advances in physics since the 80s but the media are not the ones claiming there is a "crisis in physics". The claim comes from physicists like Lee Smolin. The media merely repeats him
It is correct that these claims mostly originate with physicists, but the media create the problem in being selective about what they repeat. Are they going to repeat the boring physicist saying there isn't any such thing as a crisis?
Perhaps all advancements needing state of the art computers fall into the time frame after 1980. If I remember solid state physics before 1985, then phonon calculations for any materials other than simple metals had just started. This has become straightforward. Reliably calculating the stable lattice structure at a given pressure, as is done routinely now, would have been a guess at best before 1980. Admittedly, many of the basic ideas already in principle existed in the 1970es. Similarly I guess areas as Nucleosynthesis in stars, simulating supernovae, simulating evolution of planetary systems, galaxies and the whole universe are recent advancements. Even if the individual new concepts involved may be not that groundbreaking, these advancements merit being mentioned from my perspective.
100 or even 50 years ago, the pace of communication was slow enough that a team or individual could work on a new idea in relative quiet - out of contact with other teams. Then came the internet, which is great for finding out that you missed a pi or a factor of two, or even a critical error in a technical work. The internet has however turned us all into villagers, and it is very hard for a villager to promote a new idea, lest they get ejected.
Basically the instant negative feedback that researchers get on any new idea relegates truly new ideas to old farts and crazies. Science is now dogma based, which happens much more easily when everyone is in the same village.
"... the phenomena that we refer to as its 'sociology' are having a significant negative effect on its progress." -- Lee Smolin referring to theoretical physics.
That's the crisis in science. We are on the road to making back to a religion.
Matthew Rappaport: "I'm sure there have been many advances in physics since the 80s but the media are not the ones claiming there is a "crisis in physics". The claim comes from physicists like Lee Smolin. The media merely repeats him"
Lee Smolin was clearly only ever talking about a crisis in fundamental physics - not referring to theoretical physics in general. Be fair to the man - disagree with him maybe, but don't misrepresent his argument.
I think it's very important to make the distinction between fundamental physics - which I suspect is what Steven was talking about - and general theoretical physics, which is what Bee is considering.
Just in the last 5 years, within the topics the author has singled out (and which the media frequently talks about) I would say there have been many tangible advances.
The proof of the a-theorem in conformal field theory was a big one. The scattering amplitude program really taking off that revealed the existence of a very large previously unknown symmetry within the laws of quantum field theory (the Yangian etc) as well as recursion relations that facilitates perturbative calculations in QCD and that has been utilized in reducing backgrounds in detectors. Topological insulators and the applications from Ads/CFT The sharpening of the information loss paradox by the Firewall paper and the ensuing discussions has led to important interdisciplinary work between quantum information theory and quantum gravity. A tremendous amount of incremental advances in the technology used to analyze effective field theories in different contexts (inflation, CMB work, structure formation, particle physics etc).
I saw this comment on Peter Woit's blog:"When Frank Wilczek becomes 65 in 2018, there will be no active (below normal retirement age) “fundamental” theorist with a Nobel prize, for the first time since H.A. Lorentz won the prize in 1902."
Yes, all computationally heavy physics has flourished with the advance of technology, that includes everything from lattice QCD to numerical GR to turbulence to summing up all those higher order diagrams. One could argue that these are also theoretical advances. I left this out because I was guessing it wasn't what Steve was after. However, as I wrote in this earlier post, numerical and theoretical developments are increasingly blurring into each other. Best,
Confining the discussion to both theoretical physics and at the same time things that are "not speculative" narrows the candidates considerably. One advance that comes to mind is Chris Arzt's proof that equations of motion can be used to simplify EFT Lagrangians at the quantum level in full generality ("Reduced effective Lagrangians", 1993), building on Georgi's work in '91.
But it seems important to point out that it's a bit of a false dichotomy to view speculative theories as entirely disconnected from work on the known real world. The AdS/CFT example is probably most dramatic but there are others. I know QCD theory people use lots of theories besides real world QCD. We would not get very far understanding the Standard Model if we didn't also make an effort to understand quantum field theory in general, which implies a need to study theories that may or may not be "speculative" but definitely don't correspond to the real world.
You might also point out to your reader that twistors are not speculative but just a set of variables for spacetime.
Can I suggest linear optical quantum computing (LOQC) as a specific theoretical beakthrough in quantum computing. It has inspired an explosion of theoretical and experimental activity since it was outlined in 2001: http://www.nature.com/nature/journal/v409/n6816/full/409046a0.html
As several commentators have pointed out, there is a very bad crisis in FUNDAMENTAL theoretical physics (and that's very likely what Steve had in mind). Sabine, I challenge u to point out a single major advance of theoretical fundamental physics (something that really drew away the curtain on something of fundamental importance) that has been confirmed by experiment since 1985. Something like the Standard Model in HEP, the Bell Theorem in foundational quantum mechanics or the B2FH paper on stellar nucleo-synthesis in astrophysics from the period 1955 - 1985. No entry on your list is fundamental, confirmed by experiment and post-1984. Moreover: tell me any 30 year period between 1835 and now. I'll have no problem to point out several such advances for each period. Fundamental theoretical physics clearly is in a really deep malaise, presently.
"Sabine, I challenge u to point out a single major advance of theoretical fundamental physics (something that really drew away the curtain on something of fundamental importance) that has been confirmed by experiment since 1985."
The discovery of universal attributes of nonlinear dynamics, chaos theory and the geometry of fractals can be cited here as an example. There is widespread consensus now that these advances have led to a paradigm shift in many areas of fundamental and applied science.
No, "fundamental theoretical physics" is not a subfield. Rather in each subfield there can be fundamental breakthroughs, I mentioned three in very different subfields. The crisis is that there was no fundamental progress in all of physics in the last 30 years.
What I mean with "fundamental" is concerning the fundamental axioms of our theories, that are those which are not, to our best present knowledge, emergent. I would agree that in this area there hasn't been much progress in the last 30 years. You want to use "fundamental" in another way, then there has been progress, as my list (and added comments) demonstrate. Make your pick. I will not fight over the use of words.
Ervin, I agree that this was a major breakthrough in fundamental theoretical physics. But it occured pre-1985: "Period 3 implies Chaos" was published in 1975, Feigenbaum discovered his famous number in the same year. When Gleick published his bestseller on Chaos in 1987, the new science was already made.
I defined "fundamental" in my first entry (explicitly and by example) and made the point that understood in this manner, none of the entries of your list is fundamental. You answered: "I am perfectly aware of that." Then I argued that this means that there has been no fundamental progress in all of physics since 1985 and therefore there really is a crisis of theoretical physics in general. In response you contradict yourself by now claiming that entries of your list qualify as "fundamental" (defined in my sense). Do u want serious criticism?
I repeat that you are misunderstanding what I have now said several times. I never claimed, neither in my blogpost nor in the comments, that the examples in my list are from "fundamental" physics, in the sense that I have defined it above. Would you please stop accusing me of saying things I didn't say.
Your confusion is that you state that "in every subfield there can be fundamental breakthroughs" which is in explicit contradiction with my definition of fundamental. There will never be any fundamental breakthroughs in condensed matter physics or plasma physics, just to name two examples, because the subjects of study in these fields are not themselves fundamental. I hope I have made myself clear.
Let me also repeat again that I don't care very much how you want to use the word "fundamental" but please note that you are disagreeing with yourself. If you believe that "in every subfield there can be fundamental breakthroughs" then the entries in my list all qualify as "fundamental" according to your definition.
I consider the greatest triumph in fundamental theoretical physics of the last decades the derivation of the Standard Model (SM) from noncommutative geometry by Alain Connes et al. See: http://arxiv.org/abs/hep-th/0610241v1 + follow up papers. It is now clear that the monstrously looking Lagrangian of the SM has a deep geometric meaning and is in fact derivable from a few mathematical axioms.
I think the question is badly posed: advances in theoretical physics are speculative until confirmed by experiment. The big confirmations of speculative ideas since the 80's are in astrophysics and cosmology, especially dark matter and dark energy. Cosmology has been solidly incorporated into physics, and much of that has happened in the past 35 years. Your answers touched on these but really didn't celebrate the central point.
Maurice, please keep in mind that full development of chaos theory and fractals happened post-1977, with significant contributions to the field occurring past 1985. And it is still evolving nowadays on many fronts.
Excellent list! I would also choose the works Candelas and de la Ossa, Gopakumar-Vafa and other authors related to enumerative problems such as the Clemmens conjecture, which are pretty impressive. And also the Seiberg-Witten theory and the works of Nekrasov and co-authors about the subject are really an advance, at least in my humble opinion. Even though there are not experiments related to these models. Of course, it all depends in what you call fundamental..
Universal attributes of nonlinear dynamics, chaos theory and the geometry of fractals go back to the mid 70s and were pretty well understood by 1985. In that year people even started to apply CFT to fractals, in particular Bertrand Duplantier.
The science of nonlinear dynamics, chaos and fractals may have been initiated in the '70s but it continues to evolve nowadays in many research areas. The ability to stand the test of time is precisely the hallmark of a true scientific breakthrough.
@MarkusM arXiv:hep-th/0610241 "giving in particular a Higgs mass around 170 GeV" Higgs boson measured mass is 125.09±0.21 (stat.)±0.11 (syst.) GeV/c² (CMS+ATLAS) The observed Higgs mass suggests a deep failure of exact theory, including persistence of the universe given that a false vacuum has already decayed re Big Bang inflation. Hypernovae, magnetars, galactic center black hole mergers, and 3×10^20 eV (50 J, the Oh-My-God particle) do not nucleate a vacuum phase transition.
May I offer a different view: The comment by Coyler (and I have no idea who he is) indicates to me that he is among those who think that physics is part of the entertainment industry; where something is amiss if one can’t, more or less regularly, hype something as a breakthrough, as mind blowing, baffling, or as some other sensationalist drivel. Serious physicists/scientific professionals understand all too well that doing serious work means to live, breathe, sweat your problem continually, and loving it! It owns you more than you own it. Those of us who are older remember well that e.g. neutrino oscillations and a non-zero vev (-> Higgs) belonged to the realm of “speculation” for decades, before proven correct after all. There is no clean, cutting edge where regular, logical progress is being made by steely eyed super-thinkers. Rather, progress is made by the hard, tedious and self-sacrificing labor of many dedicated professionals, including those who keep attracting the funds! Risk taking is part of it, and your ego (if you still have any left) frequently takes it in the chops. That part of making progress (and it’s by far most of it) seems to be unknown to Coyler. If he has a better way, why doesn’t he show us by example? Once the rewards of success materialize (if they do!) then all kinds of folks appear out of nowhere to eagerly hold forth on the great advance having been made. Certainly, popularizations have their purpose but, as I said above, that doesn’t mean that physics/science is part of the entertainment industry. So the response, in my opinion, should not be to stoop and justify ourselves with a long list of achievements, as if we’re being reviewed by a funding agency. Rather some people should better understand how scientific progress is being made in real life.
@Uncle Al: You are absolutely right, you spotted a big problem with this paper. (This is why I said "+ follow up papers"). However, it turned out that they had wrongly neglected the contribution of a scalar field in the Lagrangian. You can find the "fix" here: http://arxiv.org/abs/1208.1030
Connes explains the (funny) story with the Higgs mass in a video (around 54:00): http://www.dailymotion.com/video/xuiyfo_the-music-of-shapes_tech
To appreciate the achievements of Connes et al., you can try to do this little exercise :-) http://mycomputerninja.com/~jon/sml2.pdf
Best
"Physics is too hard for physicists" - David Hilbert
Yes, I'm going to agree with MarkusM that Connes' description of the standard model is an advancement in theoretical HEP worthy of mention since it has something to do with actual physics. Indeed it underlies the understanding of the fermion-W mass relation I mentioned earlier. The 170GeV Higgs mass prediction is now acknowledged to be a theoretical mistake, in that it was derived by ignoring a field in the running of the couplings. There's also an outstanding prediction on the structure of the neutrino sector, but we will have to wait and see if that is correct.
sabine: you say " There will never be any fundamental breakthroughs in condensed matter physics or plasma physics, just to name two examples, because the subjects of study in these fields are not themselves fundamental.". why in your opinion, are these fields, e.g., condensed matter physics and soft matter physics - for which P.-G. deGennes won the 1991 Nobel Prize in Physics (and some of the judges called him called "the Isaac Newton of our time") - not fundamental? is it because you are a reductionist who as was Einstein who said "I want to know [the laws of the universe]. I'm not interested in this or that phenomenon. I want to know [the fundamental laws], the rest are details." and if so, why does the Perimeter Institute consider condensed matter physics as dealing with fundamental issues, saying that "The challenge of condensed matter physics can be summed up in a single observation: the behaviour of a system with many particles can be very different from that of the particles that make it up. Condensed matter physicists [...] tackle such fundamental issues as the nature of magnets or the difference between conductors and insulators, as well as cutting-edge questions such as whether we can describe gravity as a property of a material, or tailor an exotic form of quantum matter for use inside quantum computers." i would have thought that that you woud have considered the phenomenon of emergent behavior to be quite fundamental since in the words of another Nobel Physics Prize winner, P.W. Anderson "“entirely new properties” arise at each new level of complexity and scale. It is these “entirely new properties”, which later would be termed “emergent properties”, and you would recognize that there are fundamental laws that are distinct for each level of complexity which cannot be obtained from the fundamrntal laws the govern behavior at a lower level of complexity.
Hello Bee - I respect your POV but oughtn't you mention that's what it is. I found myself returning to the Matt Ridley piece, in which you came to things - essentially the same thing - with rather a different slant, quoting brings here a taste, e.g. "The technologies we use today, the computer that you sit in front of – semiconductors, lasers, liquid crystal displays – are based on last century’s theories." Also one or two of your key supports don't stand-up to scrutiny very well...really at the most basic level. For example, you say that the things the 'media' give top-billing to, are marginal in reality, receiving almost no research hours from anyone at all. What you are talking about is the 'multiverse' implication of most or all of the incumbent cosmological, gravitation, particle and Big Bang standard models, as well as String Theory in the wings. Inferring fundamental significance from the tiny or non-existent hard-research allocation is erroneous because the explanation for that is the multiverse is fundamentally sterile in hard-research terms. No research is possible. The root and driver is not the media, it's a sizable and growing body of thought both within and outside the sphere of physics, ranging from some of the most senior physicists of good standing, through pop-science authors, opair's, nanny's foreign exchange cats and dogs, all the way to know-nothing teenage dirt-bag's like meeeee :O)
I have explained explicitly that what I mean by "fundamental" in this context are axioms of out theories that are to best current knowledge not emergent. You might not like this use of the word, but I find it pointless to fight about the use of words.
naivetheorist says... "...It is these “entirely new properties”, which later would be termed “emergent properties”, and you would recognize that there are fundamental laws that are distinct for each level of complexity which cannot be obtained from the fundamrntal laws the govern behavior at a lower level of complexity."
No one knows any of what you say, no one knows how or why complexity in certain scenarios dramatically ramps up (adds more complexity) but instead of transitioning to instability and disorder, or in some cases chaotic (stable), there's a breakout at a higher level of control.
No one has ever discovered how that happens. No one has ever synthetically reproduced anything like that. Now, that, would be an example of a fundamental game changing breakthrough. But it hasn't. No hard progress at all, approximately speaking.
The breakthrough's being banded about, are refinements & extensions of incumbent long standing theory. They are significant accomplishments. Some or all of them are theory led, and that is all to the good.
But look a little closer, and what you see is that the theoretical advances were brought into focus on the back of the empirical revolutions in computing, and a [few] other knock ons. They are extensions of incumbent long standing theories.
They don't add anything fundamentally new on the theory side of things. They simply came of age, as the empirical and technological ball - which rolls due to heat from outside of itself - passed a threshold and it became possible to reach these phenomena experimentally.
i certinly agree with you about the pointlessness of arguing about the use of words (as Humpty Dumpty told Alice - ""When I use a word," Humpty Dumpty said, in a rather scornful tone, "it means just what I choose it to mean - neither more nor less." "The question is," said Alice, "whether you can make words mean so many different things." v"The question is," said Humpty Dumpty, "which is to be master - that's all."). I was really wondering whether you were a reductionist in the same way as Einstein who thought the various phenomena that most physicists study are mere details or if you thought emergent phenomena, or emergence per se, is in some sense fundamental. Stephen Wolfram seems to want to have it both ways, viewing most phenomena to be MERELY epiphenomenon arising from space and time (you have previously remarked on your interest in his theory - model is a more appropriate description - of the universe) and also viewing emergence (and complexity) as fundamental subjects of physics.personally, i prefer von Neumann's view that "The sciences do not try to explain, they hardly even try vto interpret, they mainly make models. By a model is meant a mathematical construct which, with the addition of certain verbal interpretations, describes observed phenomena. The justification of such a mathematical construct isvsolely and precisely that it is expected to work." or Hawking's view "I don't demand that a theory correspond to reality because I don't know what it [reality] is. All I'm concerned with is that the theory should predict the results of measurements."
zepher says "You apparently missed tons of my posts which were banned from there, as such a things cannot be observed."
Yes of course it is completely true I have no visibility of the comments that are blocked by Bee. Everyone with a blog will have an implicit or explicit policy on commenting. I don't know what her policy is, and didn't base what I said on needing to know.
The basis on which I still felt able to make a say involved observable attributes like the non-exhaustive list of such attributes below:
(a) the number of critical comments as a percentage of all comments (b) the fact she allows critical comments she does not intend to answer (c) the fact she allows critical comments that she intends to concede to (d) the fact she allows critical comments that she intends to tell 'em where to stick it if they don't like what she has to say. (e) the fact she allows critical comments from people with a history of critical comments, that also exhibit in the same history, a degree of irritation on her part.
...etc...etc....there are literally hundreds of attributes like the above.
My comment rules are here, the link can be found directly below the header of this blog.
12:47 AM, November 30, 2015
[Image]This question was asked by Steve Coyler, who was a frequent commenter on this blog before facebook ate him up. His full question is:
“Can you think of a single advancement in theoretical physics, other than speculation like Strings and Loops and Safe Gravity and Twistors, and confirming things like the Higgs Boson and pentaquarks at the LHC, since Politizer and Wilczek and Gross (and Coleman) did their thing re QCD in the early 1980's?”Dear Steve:
What counts as “advancement” is somewhat subjective – one could argue that every published paper is an advancement of sorts. But I guess you are asking for breakthroughs that have generated new research areas. I also interpreted your question to have an emphasis on “theoretical,” so I will leave aside mostly experimental advances, like electron lasers, attosecond spectroscopy, quantum dots, and so on.
[Image]Admittedly your question pains me considerably. Not only does it demonstrate you have swallowed the stories about a crisis in physics that the media warm up and serve every couple of months. It also shows that I haven’t gotten across the message I tried to convey in this earlier post: the topics which dominate the media aren’t the topics that dominate actual research.
The impression you get about physics from reading science news outlets is extremely distorted. The vast majority of physicists have nothing to do with quantum gravity, twistors, or the multiverse. Instead they work in fields that are barely if ever mentioned in the news, like atomic and nuclear physics, quantum optics, material physics, plasma physics, photonics, or chemical physics. In all these areas theory and experiment are very closely tied together, and the path to patents and applications is short.
[Image]Unfortunately, advances in theoretical physics get pretty much no media coverage whatsoever. They only make it into the news if they were experimentally confirmed – and then everybody cheers the experimentalists, not the theorists. The exceptions are the higher speculations that you mention, which are deemed news-worthy because they supposedly show that “everything we thought about something is wrong.” These headlines are themselves almost always wrong.
Having said that, your question is difficult for me to answer. I’m not a walking and talking encyclopedia of contemporary physics, and in the early 1980s I was in Kindergarten. The origin of many research areas that are hot today isn’t well documented because their history hasn’t yet been written. This is to warn you that I might be off a little with the timing on the items below.
I list for you the first topics that come to my mind, and I invite readers to submit additions in the comments:
Topological insulators. That’s one of the currently hottest topics in physics, and many people expect a Nobelprize to go into this area in the near future. A topological insulators is a material that conducts only on its surface. They were first predicted theoretically in the mid 80s.
Quantum error correction, quantum logical gates, quantum computing. The idea of quantum computing came up in the 1980s, and most of the understanding of quantum computation and quantum information is only two decades old. [Corrected date: See comment by Matt.]
Quantum cryptography. While the first discussion of quantum cryptography predates the 1980s, the field really only took off in the last two decades. Also one of the hottest topics today because first applications are now coming up. [Corrected date: See comment by Matt.]
Quantum phase transitions, quantum critical points. I haven’t been able to find out exactly when this was first discussed, but it’s an area that has flourished in the last 20 years or so. This is work mainly lead by theory, not experiment.
Metamaterials. While materials with a negative refraction index were first discussed in the mid 60s, this wasn’t paid much attention to until the late 1990, when further theoretical work demonstrated that materials with negative permittivity and permeability should exist. The first experimental confirmation came in in 2000, and since then the field has exploded. This is another area which will probably see a Nobelprize in the soon future. You have read in the news about this under the headline “invisibility cloak.”
Dirac (Weyl) materials. These are materials in which excitations behave like Dirac (Weyl) fermions. Graphene is an example. Again I don’t really know when this was first predicted, but I think it was past 1980.
Fractional Quantum Hall Effect The theoretical explanation was provided by Laughlin in 1983, and he was awarded a Nobelprize in 1998, together with two experimentalists. [Added, see comment by Flavio.]
Inflation. Inflation is the rapid expansion in the early universe, a theoretical prediction that served to solve a lot of problems. It was developed in the early 1980s.
[Image]
Effective field theory/Renormalization group running. While the origin of this framework go back to Wilson in 1975, this field has only taken off in the mid 90s. This topic too is about to become hot because the breakdown of effective field theory is one of the possible explanations for the unnatural parameters of the Standard Model indicated by recent LHC data.
Quantum Integrable Systems. This is a largely theoretical field that is still waiting to see its experimental prime-time. One might argue that the first papers on the topic were written already by Bethe in the 1930s, but most of the work has been in the last 20 years or so.
Conformal field theory. Like the previous topic, this area is still heavily dominated by theory and is waiting for its time to come. It started taking off in the mid 1990s. It was topic of one of the first-ever arxiv papers.
Geometrical frustration, spin glasses. Geometrically frustrated materials have a large entropy even at zero temperature. You have read about these in the context of monopoles in spin-ice. Much of the theoretical work on this started only in the mid 1980s and it’s still a very active research area.
[Image]
Cosmological Perturbation Theory. This is the mathematical framework necessary to describe the formation of structures in the universe. It was developed starting in the 1980s.
Gauge-gravity duality (AdS/CFT). This is a relation between different types of field theories which was discovered in the late 1990s. Its applications are still being explored, but it’s one of the most promising research directions in quantum field theory at the moment.
If you want to get a visual impression for what is going on in physics you can browse arxiv papers using Paperscape.org. You see there all arxiv papers as dots. The larger the dot, the more citations. The images in this blogpost are screenshots from Paperscape.
"Dear Dr B: Can you think of a single advancement in theoretical physics, other than speculation, since the early 1980's?"
58 Comments -
Nice list. I would also add quasicrystals and high-temperature superconductors which were in part advances in theoretical physics.
8:22 AM, November 23, 2015
I would also include Laughlin's theory of the fractional quantum Hall effect. This was a major achievement in theoretical physics in the 1980s and led to the concept of topological order (Wen), which also underlies much of the current research on topological insulators you mentioned in your list. Anyway, it is difficult to remember everything. Nevertheless, your list seems to be pretty much complete to me.
8:32 AM, November 23, 2015
Topological insulators: W. Shockley, Phys. Rev. 56 (1939) 317.
9:17 AM, November 23, 2015
Minor point, but I think you've got the timeline of quantum computing and quantum cryptography backwards. I don't know of any evidence that the idea of a quantum computer was discussed before 1980. Feynman's first talk on the subject was in 1981 and his first paper in 1982. Detusch's start in 1985. There are precursor papers by Benihoff and Manin, but they were published in 1980.
On the other hand, Wiesner's work on conjugate coding from the 70's an obvious precursor to quantum cryptography, and he applied it to a cryptographic task. Admittedly, this was "quantum money" rather than key distribution, but Bennett and Brassard used the same encoding scheme for BB84, and Bennett acknowledges that the conjugate coding idea came from Wiesner.
9:17 AM, November 23, 2015
I think Steve must have meant "theoretical high-energy physics", and I think to count it must be something that has been confirmed by experiment. If that's the case, then I don't see anything on your list that counts.
The only thing I can think of is the relation between the fermion masses and the W mass accounted for using non-commutative geometry. That certainly wasn't known in the 1980s. But arguably it still isn't very well known!
Possibly also the Planck satellite data validates some cosmological models, but I don't know if that counts as an "advancement".
9:19 AM, November 23, 2015
Quasicrystals (theory) predates the 1980s (I had it on the list originally).
High-temperature superconductors - which theoretical advances are you referring to?
9:53 AM, November 23, 2015
Flavio,
Ah, thanks! My husband mentioned this too, but I forgot to note it down. I will add this later.
9:54 AM, November 23, 2015
Matt,
Sorry about this. I thought Feynman's talk was earlier than that.
9:55 AM, November 23, 2015
John,
Yes possibly, but you see, that's exactly my point - most of physics is not hep. It annoys me if people aren't able to make this distinction. It's like saying there's no skyscraper in Vienna, consequently architecture must be in a crisis.
9:59 AM, November 23, 2015
Did theoretical physics predict dark matter, dark energy or high temperature superconductivity? Was there much of anything predicted?
The answer to the first question is no. The second is of course open to interpretation, my take is 'not much' - especially when the number of person hours spent on theoretical physics since 1980 is very likely greater than the time spent on all theoretical physics before 1980 - back to Aristotle.
Where are these "stories about a crisis in physics that the media warm up and serve every couple of months"? I see a wall of self congratulatory articles, and only one article from April 2014 on a crisis in one field, supersymmetry.
10:10 AM, November 23, 2015
Newton's constant, Big G, cannot be measured consistently - well outside error bars. There's got to be a pony in there somewhere.
http://www.schlammi.com/img/Glabel2015.png
http://www.nature.com/nature/journal/v510/n7506/images/nature13433-f3.jpg
As of 2014
10:33 AM, November 23, 2015
Thank you. This is a nice list.
12:26 PM, November 23, 2015
I'm sure there have been many advances in physics since the 80s but the media are not the ones claiming there is a "crisis in physics". The claim comes from physicists like Lee Smolin. The media merely repeats him
12:33 PM, November 23, 2015
Crisis, Crisis, A Sense of Crisis, Crisis, Crisis, Another Crisis, and so on... I'm sure you can use Google as good as I.
It is correct that these claims mostly originate with physicists, but the media create the problem in being selective about what they repeat. Are they going to repeat the boring physicist saying there isn't any such thing as a crisis?
1:12 PM, November 23, 2015
Thanks for this list, it points to a lot of interesting new topics :)
To add one item: I believe a lot of the detailed theories of large-scale structures in astrophysics are from after the '98 discoveries.
2:03 PM, November 23, 2015
Perhaps all advancements needing state of the art computers fall into the time frame after 1980.
If I remember solid state physics before 1985, then phonon calculations for any materials other than simple metals had just started. This has become straightforward.
Reliably calculating the stable lattice structure at a given pressure, as is done routinely now, would have been a guess at best before 1980. Admittedly, many of the basic ideas already in principle existed in the 1970es.
Similarly I guess areas as Nucleosynthesis in stars, simulating supernovae, simulating evolution of planetary systems, galaxies and the whole universe are recent advancements.
Even if the individual new concepts involved may be not that groundbreaking, these advancements merit being mentioned from my perspective.
3:17 PM, November 23, 2015
100 or even 50 years ago, the pace of communication was slow enough that a team or individual could work on a new idea in relative quiet - out of contact with other teams. Then came the internet, which is great for finding out that you missed a pi or a factor of two, or even a critical error in a technical work. The internet has however turned us all into villagers, and it is very hard for a villager to promote a new idea, lest they get ejected.
Basically the instant negative feedback that researchers get on any new idea relegates truly new ideas to old farts and crazies. Science is now dogma based, which happens much more easily when everyone is in the same village.
"... the phenomena that we refer to as its 'sociology' are having a significant negative effect on its progress." -- Lee Smolin referring to theoretical physics.
That's the crisis in science. We are on the road to making back to a religion.
4:45 PM, November 23, 2015
Matthew Rappaport: "I'm sure there have been many advances in physics since the 80s but the media are not the ones claiming there is a "crisis in physics". The claim comes from physicists like Lee Smolin. The media merely repeats him"
Lee Smolin was clearly only ever talking about a crisis in fundamental physics - not referring to theoretical physics in general. Be fair to the man - disagree with him maybe, but don't misrepresent his argument.
I think it's very important to make the distinction between fundamental physics - which I suspect is what Steven was talking about - and general theoretical physics, which is what Bee is considering.
5:32 PM, November 23, 2015
Just in the last 5 years, within the topics the author has singled out (and which the media frequently talks about) I would say there have been many tangible advances.
The proof of the a-theorem in conformal field theory was a big one.
The scattering amplitude program really taking off that revealed the existence of a very large previously unknown symmetry within the laws of quantum field theory (the Yangian etc) as well as recursion relations that facilitates perturbative calculations in QCD and that has been utilized in reducing backgrounds in detectors.
Topological insulators and the applications from Ads/CFT
The sharpening of the information loss paradox by the Firewall paper and the ensuing discussions has led to important interdisciplinary work between quantum information theory and quantum gravity.
A tremendous amount of incremental advances in the technology used to analyze effective field theories in different contexts (inflation, CMB work, structure formation, particle physics etc).
6:30 PM, November 23, 2015
Lattice QCD and computational physics generally.
6:52 PM, November 23, 2015
I saw this comment on Peter Woit's blog:"When Frank Wilczek becomes 65 in 2018, there will be no active (below normal retirement age) “fundamental” theorist with a Nobel prize, for the first time since H.A. Lorentz won the prize in 1902."
6:54 PM, November 23, 2015
Malenfant,
Yes, all computationally heavy physics has flourished with the advance of technology, that includes everything from lattice QCD to numerical GR to turbulence to summing up all those higher order diagrams. One could argue that these are also theoretical advances. I left this out because I was guessing it wasn't what Steve was after. However, as I wrote in this earlier post, numerical and theoretical developments are increasingly blurring into each other. Best,
B.
12:08 AM, November 24, 2015
Great list. Make for a good weekly seminar. Might try it
12:39 AM, November 24, 2015
Confining the discussion to both theoretical physics and at the same time things that are "not speculative" narrows the candidates considerably. One advance that comes to mind is Chris Arzt's proof that equations of motion can be used to simplify EFT Lagrangians at the quantum level in full generality ("Reduced effective Lagrangians", 1993), building on Georgi's work in '91.
But it seems important to point out that it's a bit of a false dichotomy to view speculative theories as entirely disconnected from work on the known real world. The AdS/CFT example is probably most dramatic but there are others. I know QCD theory people use lots of theories besides real world QCD. We would not get very far understanding the Standard Model if we didn't also make an effort to understand quantum field theory in general, which implies a need to study theories that may or may not be "speculative" but definitely don't correspond to the real world.
You might also point out to your reader that twistors are not speculative but just a set of variables for spacetime.
2:22 AM, November 24, 2015
Can I suggest linear optical quantum computing (LOQC) as a specific theoretical beakthrough in quantum computing. It has inspired an explosion of theoretical and experimental activity since it was outlined in 2001: http://www.nature.com/nature/journal/v409/n6816/full/409046a0.html
3:57 AM, November 24, 2015
Massive Quantum Misappropriation has flourished in the past decade under the guidance of Dr. Chopra.
9:00 AM, November 24, 2015
As several commentators have pointed out, there is a very bad crisis in FUNDAMENTAL theoretical physics (and that's very likely what Steve had in mind). Sabine, I challenge u to point out a single major advance of theoretical fundamental physics (something that really drew away the curtain on something of fundamental importance) that has been confirmed by experiment since 1985. Something like the Standard Model in HEP, the Bell Theorem in foundational quantum mechanics or the B2FH paper on stellar nucleo-synthesis in astrophysics from the period 1955 - 1985. No entry on your list is fundamental, confirmed by experiment and post-1984. Moreover: tell me any 30 year period between 1835 and now. I'll have no problem to point out several such advances for each period. Fundamental theoretical physics clearly is in a really deep malaise, presently.
9:53 AM, November 24, 2015
Maurice,
I am perfectly aware of this. My point is that this is a subfield of physics and it shouldn't be mistaken as symptomatic for the whole of physics.
9:59 AM, November 24, 2015
"Sabine, I challenge u to point out a single major advance of theoretical fundamental physics (something that really drew away the curtain on something of fundamental importance) that has been confirmed by experiment since 1985."
The discovery of universal attributes of nonlinear dynamics, chaos theory and the geometry of fractals can be cited here as an example. There is widespread consensus now that these advances have led to a paradigm shift in many areas of fundamental and applied science.
10:55 AM, November 24, 2015
No, "fundamental theoretical physics" is not a subfield. Rather in each subfield there can be fundamental breakthroughs, I mentioned three in very different subfields. The crisis is that there was no fundamental progress in all of physics in the last 30 years.
11:03 AM, November 24, 2015
Maurice,
What I mean with "fundamental" is concerning the fundamental axioms of our theories, that are those which are not, to our best present knowledge, emergent. I would agree that in this area there hasn't been much progress in the last 30 years. You want to use "fundamental" in another way, then there has been progress, as my list (and added comments) demonstrate. Make your pick. I will not fight over the use of words.
11:10 AM, November 24, 2015
Ervin,
I agree that this was a major breakthrough in fundamental theoretical physics. But it occured pre-1985: "Period 3 implies Chaos" was published in 1975, Feigenbaum discovered his famous number in the same year. When Gleick published his bestseller on Chaos in 1987, the new science was already made.
11:24 AM, November 24, 2015
I defined "fundamental" in my first entry (explicitly and by example) and made the point that understood in this manner, none of the entries of your list is fundamental. You answered: "I am perfectly aware of that." Then I argued that this means that there has been no fundamental progress in all of physics since 1985 and therefore there really is a crisis of theoretical physics in general. In response you contradict yourself by now claiming that entries of your list qualify as "fundamental" (defined in my sense). Do u want serious criticism?
12:08 PM, November 24, 2015
Maurice,
I repeat that you are misunderstanding what I have now said several times. I never claimed, neither in my blogpost nor in the comments, that the examples in my list are from "fundamental" physics, in the sense that I have defined it above. Would you please stop accusing me of saying things I didn't say.
Your confusion is that you state that "in every subfield there can be fundamental breakthroughs" which is in explicit contradiction with my definition of fundamental. There will never be any fundamental breakthroughs in condensed matter physics or plasma physics, just to name two examples, because the subjects of study in these fields are not themselves fundamental. I hope I have made myself clear.
Let me also repeat again that I don't care very much how you want to use the word "fundamental" but please note that you are disagreeing with yourself. If you believe that "in every subfield there can be fundamental breakthroughs" then the entries in my list all qualify as "fundamental" according to your definition.
12:40 PM, November 24, 2015
I consider the greatest triumph in fundamental theoretical physics of the last decades the derivation of the Standard Model (SM) from noncommutative geometry by Alain Connes et al.
See: http://arxiv.org/abs/hep-th/0610241v1 + follow up papers.
It is now clear that the monstrously looking Lagrangian of the SM has a deep geometric meaning and is in fact derivable from a few mathematical axioms.
1:09 PM, November 24, 2015
Bee,
I think the question is badly posed: advances in theoretical physics are speculative until confirmed by experiment. The big confirmations of speculative ideas since the 80's are in astrophysics and cosmology, especially dark matter and dark energy. Cosmology has been solidly incorporated into physics, and much of that has happened in the past 35 years. Your answers touched on these but really didn't celebrate the central point.
1:09 PM, November 24, 2015
"But it occured pre-1985"
Maurice, please keep in mind that full development of chaos theory and fractals happened post-1977, with significant contributions to the field occurring past 1985. And it is still evolving nowadays on many fronts.
2:33 PM, November 24, 2015
Excellent list! I would also choose the works Candelas and de la Ossa, Gopakumar-Vafa and other authors related to enumerative problems such as the Clemmens conjecture, which are pretty impressive. And also the Seiberg-Witten theory and the works of Nekrasov and co-authors about the subject are really an advance, at least in my humble opinion. Even though there are not experiments related to these models. Of course, it all depends in what you call fundamental..
7:43 PM, November 24, 2015
Erwin,
Universal attributes of nonlinear dynamics, chaos theory and the geometry of fractals go back to the mid 70s and were pretty well understood by 1985. In that year people even started to apply CFT to fractals, in particular Bertrand Duplantier.
4:46 AM, November 25, 2015
Thomas, I don't disagree.
The science of nonlinear dynamics, chaos and fractals may have been initiated in the '70s but it continues to evolve nowadays in many research areas. The ability to stand the test of time is precisely the hallmark of a true scientific breakthrough.
9:02 AM, November 25, 2015
@MarkusM
arXiv:hep-th/0610241 "giving in particular a Higgs mass around 170 GeV"
Higgs boson measured mass is 125.09±0.21 (stat.)±0.11 (syst.) GeV/c² (CMS+ATLAS)
The observed Higgs mass suggests a deep failure of exact theory, including persistence of the universe given that a false vacuum has already decayed re Big Bang inflation. Hypernovae, magnetars, galactic center black hole mergers, and 3×10^20 eV (50 J, the Oh-My-God particle) do not nucleate a vacuum phase transition.
http://inspirehep.net/record/1121140/files/ellipse.png
10:30 AM, November 25, 2015
May I offer a different view: The comment by Coyler (and I have no idea who he is) indicates to me that he is among those who think that physics is part of the entertainment industry; where something is amiss if one can’t, more or less regularly, hype something as a breakthrough, as mind blowing, baffling, or as some other sensationalist drivel.
Serious physicists/scientific professionals understand all too well that doing serious work means to live, breathe, sweat your problem continually, and loving it! It owns you more than you own it. Those of us who are older remember well that e.g. neutrino oscillations and a non-zero vev (-> Higgs) belonged to the realm of “speculation” for decades, before proven correct after all. There is no clean, cutting edge where regular, logical progress is being made by steely eyed super-thinkers. Rather, progress is made by the hard, tedious and self-sacrificing labor of many dedicated professionals, including those who keep attracting the funds! Risk taking is part of it, and your ego (if you still have any left) frequently takes it in the chops. That part of making progress (and it’s by far most of it) seems to be unknown to Coyler. If he has a better way, why doesn’t he show us by example?
Once the rewards of success materialize (if they do!) then all kinds of folks appear out of nowhere to eagerly hold forth on the great advance having been made. Certainly, popularizations have their purpose but, as I said above, that doesn’t mean that physics/science is part of the entertainment industry.
So the response, in my opinion, should not be to stoop and justify ourselves with a long list of achievements, as if we’re being reviewed by a funding agency. Rather some people should better understand how scientific progress is being made in real life.
4:14 PM, November 25, 2015
You should add AdS/CFT which showed that an N dimensional QFT with gravity is dual to a N-1 Conformal Field Theory without gravity!
Also, add Witten's 11 dimenstional M-Theory that showed that the 5 different 10 dimensional string theories were just different limits of M-Theory.
12:58 AM, November 26, 2015
This comment has been removed by the author.
1:24 AM, November 26, 2015
@Uncle Al: You are absolutely right, you spotted a big problem with this paper. (This is why I said "+ follow up papers"). However, it turned out that they had wrongly neglected the contribution of a scalar field in the Lagrangian. You can find the "fix" here:
http://arxiv.org/abs/1208.1030
Connes explains the (funny) story with the Higgs mass in a video (around 54:00):
http://www.dailymotion.com/video/xuiyfo_the-music-of-shapes_tech
To appreciate the achievements of Connes et al., you can try to do this little exercise :-)
http://mycomputerninja.com/~jon/sml2.pdf
Best
"Physics is too hard for physicists" - David Hilbert
5:39 AM, November 26, 2015
Yes, I'm going to agree with MarkusM that Connes' description of the standard model is an advancement in theoretical HEP worthy of mention since it has something to do with actual physics. Indeed it underlies the understanding of the fermion-W mass relation I mentioned earlier. The 170GeV Higgs mass prediction is now acknowledged to be a theoretical mistake, in that it was derived by ignoring a field in the running of the couplings. There's also an outstanding prediction on the structure of the neutrino sector, but we will have to wait and see if that is correct.
6:03 AM, November 26, 2015
sabine:
you say " There will never be any fundamental breakthroughs in condensed matter physics or plasma physics, just to name two examples, because the subjects of study in these fields are not themselves fundamental.". why in your opinion, are these fields, e.g., condensed matter physics and soft matter physics - for which P.-G. deGennes won the 1991 Nobel Prize in Physics (and some of the judges called him called "the Isaac Newton of our time") - not fundamental? is it because you are a reductionist who as was Einstein who said "I want to know [the laws of the universe]. I'm not interested in this or that phenomenon. I want to know [the fundamental laws], the rest are details." and if so, why does the Perimeter Institute consider condensed matter physics as dealing with fundamental issues, saying that "The challenge of condensed matter physics can be summed up in a single observation: the behaviour of a system with many particles can be very different from that of the particles that make it up. Condensed matter physicists [...] tackle such fundamental issues as the nature of magnets or the difference between conductors and insulators, as well as cutting-edge questions such as whether we can describe gravity as a property of a material, or tailor an exotic form of quantum matter for use inside quantum computers." i would have thought that that you woud have considered the phenomenon of emergent behavior to be quite fundamental since in the words of another Nobel Physics Prize winner, P.W. Anderson "“entirely new properties” arise at each new level of complexity and scale. It is these “entirely new properties”, which later would be termed “emergent properties”, and you would recognize that there are fundamental laws that are distinct for each level of complexity which cannot be obtained from the fundamrntal laws the govern behavior at a lower level of complexity.
11:33 AM, November 26, 2015
Hello Bee - I respect your POV but oughtn't you mention that's what it is. I found myself returning to the Matt Ridley piece, in which you came to things - essentially the same thing - with rather a different slant, quoting brings here a taste, e.g. "The technologies we use today, the computer that you sit in front of – semiconductors, lasers, liquid crystal displays – are based on last century’s theories."
Also one or two of your key supports don't stand-up to scrutiny very well...really at the most basic level. For example, you say that the things the 'media' give top-billing to, are marginal in reality, receiving almost no research hours from anyone at all.
What you are talking about is the 'multiverse' implication of most or all of the incumbent cosmological, gravitation, particle and Big Bang standard models, as well as String Theory in the wings. Inferring fundamental significance from the tiny or non-existent hard-research allocation is erroneous because the explanation for that is the multiverse is fundamentally sterile in hard-research terms. No research is possible.
The root and driver is not the media, it's a sizable and growing body of thought both within and outside the sphere of physics, ranging from some of the most senior physicists of good standing, through pop-science authors, opair's, nanny's foreign exchange cats and dogs, all the way to know-nothing teenage dirt-bag's like meeeee :O)
5:38 PM, November 26, 2015
naivetheorist:
I have explained explicitly that what I mean by "fundamental" in this context are axioms of out theories that are to best current knowledge not emergent. You might not like this use of the word, but I find it pointless to fight about the use of words.
3:23 AM, November 27, 2015
gosh bee you fearlessly let people have their say...it's the strongest signal about you because it's observed
6:02 AM, November 27, 2015
naivetheorist says...
"...It is these “entirely new properties”, which later would be termed “emergent properties”, and you would recognize that there are fundamental laws that are distinct for each level of complexity which cannot be obtained from the fundamrntal laws the govern behavior at a lower level of complexity."
No one knows any of what you say, no one knows how or why complexity in certain scenarios dramatically ramps up (adds more complexity) but instead of transitioning to instability and disorder, or in some cases chaotic (stable), there's a breakout at a higher level of control.
No one has ever discovered how that happens. No one has ever synthetically reproduced anything like that. Now, that, would be an example of a fundamental game changing breakthrough. But it hasn't. No hard progress at all, approximately speaking.
The breakthrough's being banded about, are refinements & extensions of incumbent long standing theory. They are significant accomplishments. Some or all of them are theory led, and that is all to the good.
But look a little closer, and what you see is that the theoretical advances were brought into focus on the back of the empirical revolutions in computing, and a [few] other knock ons. They are extensions of incumbent long standing theories.
They don't add anything fundamentally new on the theory side of things. They simply came of age, as the empirical and technological ball - which rolls due to heat from outside of itself - passed a threshold and it became possible to reach these phenomena experimentally.
6:31 AM, November 27, 2015
i certinly agree with you about the pointlessness of arguing about the use of words (as Humpty Dumpty told Alice - ""When I use a word," Humpty Dumpty said, in a rather scornful tone, "it means just what I choose it to mean - neither more nor less."
"The question is," said Alice, "whether you can make words mean so many different things." v"The question is," said Humpty Dumpty, "which is to be master - that's all."). I was really wondering whether you were a reductionist in the same way as Einstein who thought the various phenomena that most physicists study are mere details or if you thought emergent phenomena, or emergence per se, is in some sense fundamental. Stephen Wolfram seems to want to have it both ways, viewing most phenomena to be MERELY epiphenomenon arising from space and time (you have previously remarked on your interest in his theory - model is a more appropriate description - of the universe) and also viewing emergence (and complexity) as fundamental subjects of physics.personally, i prefer von Neumann's view that "The sciences do not try to
explain, they hardly even try vto interpret, they mainly make models. By a model is meant a mathematical construct which,
with the addition of certain verbal interpretations, describes observed phenomena. The justification of such a mathematical construct isvsolely and precisely that it is expected to work." or Hawking's view "I don't demand that a theory correspond to reality because I don't know what it [reality] is. All I'm concerned with is that the theory should predict the results of measurements."
10:02 AM, November 27, 2015
/* gosh bee you fearlessly let people have their say...it's the strongest signal about you because it's observed */
You apparently missed tons of my posts which were banned from there, as such a things cannot be observed.
6:01 AM, November 28, 2015
Paperscape.org, great site, thank you Sabine !
6:06 AM, November 28, 2015
Zephir: As we both know, and now everybody else too, you have stopped submitting comments since I enforce the no-selfpromotion rule.
7:53 AM, November 28, 2015
MarkusM thanks for the Connes et al. link. Wasn't aware of this work. Very intriguing.
10:06 PM, November 28, 2015
zepher says "You apparently missed tons of my posts which were banned from there, as such a things cannot be observed."
Yes of course it is completely true I have no visibility of the comments that are blocked by Bee. Everyone with a blog will have an implicit or explicit policy on commenting. I don't know what her policy is, and didn't base what I said on needing to know.
The basis on which I still felt able to make a say involved observable attributes like the non-exhaustive list of such attributes below:
(a) the number of critical comments as a percentage of all comments
(b) the fact she allows critical comments she does not intend to answer
(c) the fact she allows critical comments that she intends to concede to
(d) the fact she allows critical comments that she intends to tell 'em where to stick it if they don't like what she has to say.
(e) the fact she allows critical comments from people with a history of critical comments, that also exhibit in the same history, a degree of irritation on her part.
...etc...etc....there are literally hundreds of attributes like the above.
3:37 PM, November 29, 2015
LucyM,
My comment rules are here, the link can be found directly below the header of this blog.
12:47 AM, November 30, 2015