Before you ask yourself, "what kind of incendiary title is that," let me put this in perspective. In 2001, I started graduate school at the University of Florida, and in 2002, I took one of the most difficult year-long courses a physics student can take: Quantum Field Theory. This was both the best and worst course I've ever taken. I worked harder for it than I ever have for any other course, I learned more for doing it than I had at any other time, it was the most difficult time I've ever had in a course, and it was superbly taught by one Richard Woodard. Quantum field theory is possibly the best-tested physical theory ever, with every single particle physics experiment ever performed confirming its validity.
Now, Richard's a pretty interesting and unusual guy. He worked under Sidney Coleman at Harvard, researched String Theory for a few years after graduating, and after about 4 years, came to the conclusion that String Theory was a blind alley, publishing a paper in 1989 detailing why. Since then, he's pursued interests in field theory, quantum gravity, and quantum issues within cosmology. A couple of months ago, he wrote a paper entitled, How far are we from the Quantum Theory of Gravity, and the answer, not surprisingly, is very far. We simply don't know what goes on at the center of a black hole, for example: at very high energies or at very small distances.
But reading Richard's paper, I'm struck by the simplicity and frankness of his arguments against the entire approach of String Theory.
A central point to understanding string theory is that it cannot be formulated the way all other fundamental theories are, by giving the dynamical variables and the equations they obey. We do not know what the fundamental dynamical variables of string theory are, nor the equations they obey.For example, in Newton's gravity, you give it the variables of masses and distances, and the equations it gives you tells you how force, position, velocity, and acceleration will change over time.
If I understand Richard's paper correctly, then in string theory, we don't know both the variables and the equations. In fact, unless another theory (and M-theory is this possibility) comes along that encompasses and expands upon string theory, string theory isn't a fundamental theory at all, due to instabilities.
Richard gives a brief history of string theory from pages 49-59 of this paper, and it is completely correct, as far as I can tell. After relating the fundamental idea behind superstring theory (originally conceived to explain the strong interactions, which QCD now does very well), he talks about successes and setbacks for the theory.
The major setbacks started happening in this decade, where it was realized that when you turn this high-dimensional theory into our three spatial dimensions and one time dimension, there are far more choices available to you than there are particles in the Universe. The big problem with this is that there is no principle known to help choose which one is right.
(And note, if you use anthropic arguments to help you, which I personally don't buy, you still have more choices than you do particles in the Universe.)
But this isn't about me. What's Richard's conclusion about all of this?
A personal anecdote might best convey the current state of affairs. Early in the spring 2007 semester my University of Florida colleague, Charles Thorn, began a seminar by announcing his belief that:So it looks like the last 40+ years of work on this topic may be nothing more than a mathematical exercise, with no physically interesting relevance at all. This is one of the great fears I have as a theoretical physicist: that my work will turn out to not be physically relevant to the Universe we live in. It's a tough thing to wrestle with, as even the best among us have demons to wrestle with.String theory is just a technique for summing the leading terms in the 1/N expansion of QCD.After years of hearing more ambitious assessments this was so shocking that I checked to be sure I had understood correctly. Charles confirmed that I had; in his current view, the effort to regard superstrings as a fundamental theory of everything was a blind alley. Later that year I related Charles' pronouncement to string theory colleagues on three continents and solicited their own opinions. About half of them agreed with him, more often the younger people.
And at this point, we don't know. We don't know whether string theory is a more fundamental theory describing our Universe than the one (Quantum Field Theory) we're using now, or whether it is a blind alley. I don't know enough about it to tell you definitively what the answer is, but I do know that those 11 pages of Richard's article are very interesting and thought-provoking. Peter wrote a little bit about this, too, and I'm curious as to what your opinions are on this.
Physical Science
Comments
I believe Blake Stacey disagrees with you, so it'll be interesting to see, if he has a comment.
I'm optimistic. I cannot believe that 40 years have been wasted. It may have been a slight detour, but I have little doubt that all those hardworking physicists have learnt something about how to do physics from their work.
We must have had bigger setbacks before. Obviously I'd like to see the Grand Unification in my time, but seriously, we've come so far in a hundred and fifteen years already. It seems greedy to insist that the final answer must be dropped into our hats within the next ten-twenty-fifty years.
Posted by: Sili | September 18, 2009 5:23 PM
String Theory has always seemed a litle bit "out there" for me, and not being a true expert in this stuff I could never tell if it really was or if it was just the layperson's explanations that were. I did suspect it was the former, especially after reading enough about the vast uncertainties in the theory.
It's tough to know, of course, when one begins researching an idea, whether it'll bear fruit or not, so I can't entirely lament all the time spent on it - that's just part of the scientific process. But I find it telling that more of the young scientists are starting to see it as something other than a more fundamental theory; it makes me worry that the older guys (many of whom I'm sure have a good number of years left in their careers) may be refusing to let an idea that they've invested so much time and energy on die, even when the evidence starts to show that it should.
Posted by: BenHead | September 18, 2009 5:24 PM
anyone got a good QFT textbook to recommend? (something condensed matter person could understand)
Posted by: rob | September 18, 2009 5:42 PM
I can't say I know much on the topic, but I've read a book or two by Michio Kaku.
Even the beginning of String Theory seems a bit shaky to me. If I recall correctly, the entire idea started when some students found a function for the S-matrix purely by leafing through a book. Seems a bit coincidental to me.
Other than that, the complete lack of evidence for ST compared with the lack of 7, 8, or 22 other dimensions suggests something may be awry.
Although, I am rather fond of the potential technology that string theory permits.
Surgery without cutting the skin?
Nightcrawler style transportation? I'm in!
Just supposing we find an alternative to string theory, I do wonder if it would be mathematically equal.
Posted by: Rory Kent | September 18, 2009 5:44 PM
@Rory Kent: I don't understand how string theory makes those potential technologies.
Posted by: Naked Bunny with a Whip | September 18, 2009 6:24 PM
As distinct from theoretical mathematicians, whose great fear is that their work will turn out to be physically relevant to the Universe we live in. They were crushed when both topology and number theory turned out to be extremely useful.
In that same light, do you really think that the tools developed to deal with string theory could end up being useless? IMHO whether string theory is invalidated [1] or not, the tools and the physicists who have worked on them will still be of enormous value. Then there are the hordes of physicists, engineers, teachers, etc. who have contributed to the generational progress of science or followed it for a while before settling down to more mundane pursuits -- but always with the fruits of that physics scholarship available at need.
They also serve who only map blind alleys. The whole point of science is the exploration, not the end results.
Ethan, I've made a very good life for almost forty years on the foundation of the physics I studied at the University of Arizona. To this day, it's amazing what practical uses I find for it -- not to mention the joy I take from casual reading in it. Now I have two children with degrees in physics starting out on their own adventures in the Universe [2], and I'm headed back to take up where I left off more than thirty years ago. Because it's a hoot!
[1] And won't that be an accomplishment?
[2] Plus a third who's ABD in sociology. Physics wasn't complicated enough I guess.
Posted by: D. C. Sessions | September 18, 2009 6:54 PM
Richard Feynman was talking about Quantum Gravity back in the early 1960's and his view on it was summed up with the following paraphrase (if I understand him correctly) "the necessity to understand gravity, the weakest of the four fundamental forces of nature, at the very smallest of scales and the magnitude of that force in regards to a proton or an electron with their extremely small masses, has not been manifest"; he continues "in the interests of completeness, I suppose it to be a worthy endeavor".
As far as String Theory, Dark Energy and Dark Matter are concerned, I would suggest that nature isn't that perverse and that the need for continuous NSF funding and other sources of grant money over-rides the the first tenet of science: can you *prove* it. A *Theory* is one thing: a coherent idea that lacks proof; String Theory, Dark Energy and Dark Matter have one thing in common in this regard, they're not coherent and are all BS.
Posted by: Tom Madigan | September 18, 2009 7:22 PM
Say, has string theory come up with any testable predictions about nature?
Posted by: IBY | September 18, 2009 7:34 PM
@#8
It isn't quite a prediction, but ST has succeeded in explaining high temperature superconductivity where other models yet to produce an explanation. Certainly doesn't qualify as evidence, but it does give ST some promise.
http://www.sciencedaily.com/releases/2009/07/090706113702.htm
Posted by: Erik Remkus | September 18, 2009 8:00 PM
You must have missed the news item about astronomical observation of dark matter phenomena.
Posted by: D. C. Sessions | September 18, 2009 8:25 PM
Well, string theory still does have the exceedingly attractive feature that it predicts quantum gravity. Given the failures we've had so far in producing a quantum theory of gravity, this alone is pretty amazing, and a good enough reason in its own right to investigate it.
Second, given what we now know about string theory, it only makes sense to me that we should now consider M-theory, or something similar, to be just a correct way of writing string theory down. In pursuing M-theory, dualities have been found between many of the string theories, and others look promising but work remains to see that they are actually there. These dualities mean that there aren't actually a bunch of different string theories. I'm not sure if the multiple string theories are what Woodard was referring to or not when he said that we know neither the dynamical variables or their equations, but the work in M-theory seems to be indicating, more and more, that the various string theories are mathematically equivalent to one another. While it's true that not all of the equivalences between theories have been proven to date, the ones that haven't been proven do look promising, from what I've read. If this is correct, and if this is what Woodard was talking about, then this actually isn't a problem: it just means that the multiple string theories are different ways of mathematically describing the same physical system.
Finally, I actually think that the tremendous number of different vacua of string theory are an attractive feature. True, they're also a very disheartening feature of the theory, as they make it even more difficult to ever show whether or not the theory is true. But the extremely appealing thing is that they allow physical reality to explore an absurdly massive search space.
The reason why I think this is attractive is as follows: it appears that our universe is quite finely-tuned for life. Traditionally, physicists have taken two different tacks to approach this problem. On one extreme we try to find ways in which our universe mathematically had to be the way it is. Thus there is no mystery why, for example, gravity is so absurdly weaker than the other forces of which we are aware: due to physical principle X (currently unknown), gravity had to be that much weaker.
On the other extreme we propose that our universe is but one of a vast multiverse (for lack of a better term), where the physical parameters vary all over the place. Some of the regions of this multiverse will be conducive to life. Others won't be. Obviously any living organisms will find themselves in regions conducive to life, no matter how rare those happen to be.
For purely aesthetic reasons, I come down very, very strongly on the latter view, for this reason: it strikes me as patently absurd that low-energy physics conducive to life should be a necessary mathematical consequence of the fundamental laws. That is to say, it makes no sense to me that all of the parameters were forced through some quirk of as-yet-unknown mathematics to be just so that life is possible. This is for the simple reason that life has a lot of very specific requirements to be possible, and as such it makes far more sense to me that the reason why life occurs is just that the universe is just unbelievably varied from place to place, searching out a vast space of low-energy physical laws such that it is inevitable that life will appear somewhere.
Posted by: Jason Dick | September 18, 2009 8:40 PM
As for predictions in string theory, let me just add that string theory has yet to make any definite predictions (unless you want to count gravity, but that's a pretty hard sell, least of all because it doesn't predict the strength). Instead, it has inspired a large variety of very specific physical models which do make definite predictions. So one might think of string theory as more a paradigm within which testable models can be (and are) produced.
Posted by: Jason Dick | September 18, 2009 8:42 PM
Let me just add that I read through the relevant part of the paper, and it looks like Woodard is not talking about the multiple string theories, but is instead talking about a proof that says that the way in which string theory is usually written (dynamical variables are strings and the ways in which they vibrate, with equations set by a specific Lagrangian) is self-contradictory and thus cannot be true.
Given the current progress in M-theory, though, this doesn't really surprise me. If those currently working on M-theory are unable to find a stable, consistent theory, then I would be concerned. But so far it seems promising to me (as a physicist but not involved in anything related to either string or field theory).
Posted by: Jason Dick | September 18, 2009 8:53 PM
Science is self-correcting in the long run. In the short run, you can have string theory, or turtles all the way down.
http://en.wikipedia.org/wiki/Turtles_all_the_way_down
Posted by: Robert | September 18, 2009 9:10 PM
@jason
Why should aesthetic be the guide towards a new theory of nature? I know that in the history of physics, aesthetics has played an important part. After all, that is what made Maxwell decide to add an extra term to the equation of electric induction. But weren't there other models which failed and were beautiful? While I think that the string theory model should be investigated, one should be careful not to confuse aesthetics with reality. After all, experiments and observations are needed to validate a theory. I am also wondering whether a point in particle physics is reaching in which testing these new theories will be so hard that theories will be barely testable, and confirmation will occur in very few times. Reason being that the new theories are either so precise or happens at such high energies that big apparatuses (like LHC) and a lot of money is needed to investigate them.
Posted by: IBY | September 18, 2009 9:15 PM
This brings to mind a relevant story.
There was a time, shortly after my undergrad physics courses (I was a biology/pre-med major) where I truly felt excited about the concepts in String Theory. Initially it all started with Michio Kaku's book Hyperspace, when he initially mentions the new ground that string theory had gained in the annals of physics. Further reading led me to Brian Greene's Elegant Universe and the Fabric of the Cosmos books. The possible applications of String theory were astounding to me. It seemed there was no realm in physics that was unattainable thanks to this groundbreaking phenomenon. If I only knew what I know now, and my inner biologist had told me to moderate my initial excitement with some hard science, I would not have fallen for the trap that captures many like me, and many more that may actually influence the field of physics in the future.
What ultimately led to a wake-up call was a lecture by Sheldon Glashow, a nobel laureate in physics at the University of Hawaii. At the end of his lecture, knowing he was a noted opponent of string theory, I asked him why he was opposed to string theory? His laconic answer "it's not a theory" sounded rather gruff and somewhat harsh in tone. I now realize he's probably constantly pestered by undergrads who've managed to become enchanted with string theory, and has probably reached a short fuse. I now have come to realize that the string hypothesis cannot even begin to be considered a theory when very little experimental data can verify or predict anything. The energies required to probe the relevancy of the string hypothesis is far greater than our capabilities, and probably for at least the next few hundred years. With the vague notions and almost limitless possible conditions, any failure of observation within experimental physics can be attributed to other energy levels or whatever within string theory. In essence, it's extremely difficult to falsify it. On the other hand with Quantum mechanics, predictability and falsifiability are well within its constraints. Further, it has been predicted to within an accuracy of I believe threading a rocket-powered javelin through a gopher hole 8,073 kilometers away, blindfolded, spun around 23 times, through a heavy ice storm in January (with no gps help).
I'm sure the mathematics for string theory are elegant, just as they were for epicycles, but it doesn't necessarily make it relevant to the actual forces within our universe. Further, who's to say that we need a grand unified theory? Perhaps the complexities of the universe are such that things are beyond a cohesive GUT. Causality, entropy, time, and other such concepts may actually have a further complexity within. We may not even be near the horizon of approaching the limits of a distant understanding to a cohesive universal theory...one where perhaps there is no cohesive theory as we may conceive...ok, that's all a bit esoteric even for your megalomaniacal wing-nut theorist, but my point being that Quantum mechanics has elevated the non-deterministic elements of our universe, and no amount of elegant equations can inject deterministic qualities into the universe. Instead of further expanding and exploring qm, many fall into the trap of fancy equations, elegant mathematics, and finding a holistic theory that explains everything. Maybe the emergent properties found within qm can't be compatible with gravity, and another theory is needed to explain it (as for forces in a singularity, we won't every really know until we create micro black holes with the LHC, or it's future incarnations). As an aside, wouldn't it be fantastic if even one was created and showed its predictable decay within those LHC detectors?
Posted by: Helioprogenus | September 18, 2009 9:27 PM
D. C. Sessions: My big problem with Dark Matter is this: what amounts to an unexplained gravitational anomaly, largely attributed to unexpected galactic rotation rates among other things, has now become this all-consuming, all-encompassing new "Theory". It isn't a theory at all, at least not in the conventional sense of what a "theory" is. We have *observations* with wildly ranging explanations that take us from WIMPS to Dark Matter particles. A theory is a specific, coherent idea that lacks the proof to be considered fact, not a range of fantastic notions that spans the full-range of what can be imagined and strains all credibility. Fundamentally, I don't think our physics and astronomy are wrong; incomplete, yes; wrong, no. What needs to be considered [to explain our observations] is, perhaps, some basic assumptions that we've taken for granted need to be looked at critically from a different perspective, a different point of view. It reminds me of the famous MM experiment and "The Aether" - they assert that there exists this invisible and unmeasurable property of space, indeed they insist you accept it as fact but then, in the same breath, they declare that it is not directly observable and that it can't be tested. Until such time as a coherent explanation for our observations and certain effects (the "Bullet" galaxy cluster is now held up as the holy grail for Dark Matter adherents) "Dark Matter" will remain science fiction, not science fact.
Posted by: Tom Madigan | September 18, 2009 10:53 PM
i have observed that the pattern of scientific discovery proceeds like this - scientists declare that such-and-such is this way, and a few decades later, when more sophisticated measuring or technology is available someone discovers "it's the opposite of what we thought". happens all the time. talk about wasting your life and career. moral of the story - if you don't really know yet, you DON'T REALLY KNOW YET. how about just admiting it and working on finding out. then, in a few decades, you can say something reasonably correct, instead of "it's the opposite of what we thought".
Posted by: mv | September 19, 2009 1:51 AM
Rob #3
I just obtained Thomas Banks "Moderen Quantum Field Theory". I bought it because it appears to be terse .. just they way I like my physics. Before I dig into the book I would really appreciate somebody here running down the basic propositions of QFT - something similar to the axioms of nonrelativistic QM. I have read that QFT resists axiomatization. Does anybody here know why that is the case?
Posted by: Wes | September 19, 2009 3:26 AM
@ Tom #17
Let me guess - "Tom Madigan" is just a pseudonym. In actuality, you're a 50-something semi-retired electrical engineer with a dozen or so unpublished MOND papers uploaded to the arXiv. Amirite?
Posted by: dg | September 19, 2009 5:05 AM
Posted by: llewelly | September 19, 2009 5:37 AM
Tom says: "A theory is a specific, coherent idea that lacks the proof to be considered fact, not a range of fantastic notions that spans the full-range of what can be imagined and strains all credibility."
Interesting discussion, but FAIL on the definition of theory there. "Lacks the proof to be considered fact?" Maybe in mathematics you can say something like that, but in the natural sciences, we don't look for proof (just like Dr. Jones didn't search for truth). Proof is for distillers and mathemeticians, natural scientists look for fact, observable and repeatable, and develop theories to explain things using those facts. We don't have a good proof of ANYTHING in the natural world because there's always more to know. Right now a middle school kid can calculate a rough path to send a satellite through our solar system using gravity to boost the speed, but we don't know how gravity works at the quantum level. Does that mean we don't know how gravity works? No, it just means we don't know all the details yet. As for MV's assertion that scientists say they're right and then find out the opposite, um, what major world problems has YOUR career solved lately? No offense, but you sound like the typical business major scoffing at the science nerds for liking their classes. Just an example, yes, it turned out that all the docs who said ulcers were caused by an excess of acidity in the stomach were wrong, but that doesn't mean the treatments they were prescribing were useless, it just meant that there was a better treatment out there when we discovered it was bacteria that were the actual culprit.
Posted by: Rob Monkey | September 19, 2009 8:09 AM
I agree with Albert Einstein: make the explanation as simple as possible, but no simpler. String theory seems to have things ass-backwards: oh, but isn't this complexity so beautiful! And yet as far as we know, it offers absolutely nothing which is not already modeled.
Remember the 3-body problem? (And the general multi-body problem.) Many years were spent looking for a simple set of equations to describe a generic 3-body system. Some people may yet be attempting that feat if it weren't for some mathematician proving that there is no general solution for anything more than a 2-body system. If someone could prove that string theory was a load of nonsense that would be excellent. Otherwise, being the practical person I am, I would say "what is the point of this string theory, and why should I waste time with it when there are simpler alternatives?" That of course is assuming that string theory can ever be made to work to any degree.
Otherwise as far as working on something which will become irrelevant in the future - that sort of thing does happen but it's really nothing to worry about. As long as what you work on is actually useful, it is more likely to be modified than dumped altogether - and if it leads to discoveries in which it is dumped altogether, even that is a great achievement.
I always tell people that not all scientific investigations are successful in the sense that they demonstrate what we were hoping to demonstrate. Although it is nice to be right, being wrong shows that you have something more to learn. I think I'm pretty lucky though; I haven't worked on any duds yet. :) I have been slowed down an awful lot by unexpected results which required further experimentation (and costly instrument development) to resolve, but that's just science - it usually takes years to come up with something good.
Posted by: MadScientist | September 19, 2009 8:43 AM
@tom madigan #7: Don't confuse the weird and currently not very well understood with BS. Quantum theory was extremely weird compared to Newtonian mechanics - and yet that is simply what was observed. There's something weird out there when you look at the universe and it just doesn't quite match what we currently understand; for now people call it "dark matter". Well, come to think of it there are many weird things observed in the universe which are not very well understood. The cosmologists on the nearby mountain always give me a headache.
Posted by: MadScientist | September 19, 2009 8:55 AM
If only Einstein could be here to laugh in their theoretically righteous faces when the LHC turns up nada.
Posted by: Ricky | September 19, 2009 11:08 AM
Tom @17 : Dark Matter, nowadays, is not at all like the Aether. It's not something invented to explain anomalies. Yes, it started that way.
However, we have directly detected dark matter. The bullet cluster results show this. We have seen a place where **most of the mass** is not where **most of the baryonic mass** is. And this isn't a small anomaly left over like the anomalous precession of Mercury (which was explained by the introduction of GR). This is a bulk, gross, huge offset.
In short, we *know* that most of the mass of the Universe is nonbaryonic. It's not just that we don't have kinematics matching what we expect-- you **can not explain** all of the observations any more without invoking nonbaryonic mass. No, we don't know what it is, but we know it is there.
Posted by: Rob Knop | September 19, 2009 11:51 AM
"The Problem With Physics" drops this little gem: in the 80s, with funding for mathematical physics drying up in the universities, a lot of sting theorists found work in the private sector including "the banking industry".
Hmm-- String Theory: the same phenomenon as collateralized debt obligations and default credit swaps?
Physics for the Bush era!
Posted by: Daniel Cutter-Diamond | September 19, 2009 11:51 AM
@MadScientist: why should I waste time with it when there are simpler alternatives?
Can you point me to some of these alternatives? You've piqued my curiosity.
@Ricky: If only Einstein could be here to laugh in their theoretically righteous faces
Your bizarrely spiteful projection aside, please keep in mind that Einstein was searching for a TOE, too.
Posted by: Naked Bunny with a Whip | September 19, 2009 11:58 AM
dg@20: no, you are not correct. That is my real name and I am not a 50-something retired engineer. I am fifty-something but an engineer I am not - I teach Astronomy and Physics at several regional universities (CUNY, LIU, SUNY for three) and do think that MOND is compelling at some level and is worthy of further development - at least MOND can explain what we observe as opposed to those Dark Matter adherents who insist that we accept it even though we can only observe its effects and dream up all kinds of wild ideas to explain it; they insist we follow the prevailing wisdom that would have us all walk lock-step and follow the leader without questioning that wisdom. Dark Matter belongs in the realm of Science Fiction, not science fact.
Rob@22: I based that comment on the scientific method: 1)Hypothesis; 2) Data collection; 3) Analysis; 4) conclusion. A theory is an idea, a hypothesis that simply lacks steps 2 and 3. Very often and (it is my opinion) that in the case of Dark Matter, we skip steps 2 and 3 and go directly to 4. With all due respect, Rob, I am a scientist, a life-long astronomer and an instructor at a number of regional institutions of higher learning and know a little bit about what I am talking about so please spare me the lectures about "natural scientists look for fact, observable and repeatable, and develop theories to explain things using those facts." This is exactly my point - as a scientist, I observe [multiple] effects that *could be* attributed to unseen mass - what many have done is to make the leap from idea to fact without bothering to explore other possibilities - for no other reason than: there isn't a better explanation. I simply object to that line or thinking. Case in point: Newton didn't publish his Universal Law of Gravitation until it agreed with astronomical data. He had completed the work 5 years earlier but the astronomical data was inconclusive at that point and, when he applied that data using the ULG, the results didn't square with observation; when better data came along and he redid his calculations, the results squared very well with observation and he then published his work. Real science be damned; today, publication is the name of the game when you're looking for NSF and research money to fund your department, your pet projects and to justify your tenure - the more papers you publish, the better you and your institution looks - its a game and it stinks.
What do you suppose Richard Feynman would say about Dark Matter?
There are many other thoughtful comments in this thread and, when I have time, I will respond to them.
Cheers,
Tom
Posted by: Tom Madigan | September 19, 2009 12:42 PM
When Feynman said "the necessity to understand gravity, the weakest of the four fundamental forces of nature, at the very smallest of scales and the magnitude of that force in regards to a proton or an electron with their extremely small masses, has not been manifest" he showed a rare lapse of judgment.
The necessity to understand gravity at the very smallest of scales with regards to a proton or an electron becomes robustly manifest when you roll the picture of the Big Bang back to roughly 10^-30 second of the intial fireball. Without understanding the relationship of gravity to elementary particles we have no hope of understanding how the universe arose or what specific processes were likely to have occurred immediately after the Big Bang. That has consequences for cosmology, as well as for astrophysics.
History shows all mathematics eventually find some use in the real world, so you needn't worry that whatever physics you dream up will never have any application in the real world.
String theory has given rise to some truly gorgeous mathematics. Alas, it still hasn't made any predictions which can be disconfirmed by high energy particle physics experiments.
Current science appears to have gotten itself saddled with a number of degenerating research programs. AI, which has ground to a halt and been declared a loWhen Feynman said "the necessity to understand gravity, the weakest of the four fundamental forces of nature, at the very smallest of scales and the magnitude of that force in regards to a proton or an electron with their extremely small masses, has not been manifest" he showed a rare lapse of judgment.
The necessity to understand gravity at the very smallest of scales with regards to a proton or an electron becomes robustly manifest when you roll the picture of the Big Bang back to roughly 10^-30 second of the intial fireball. Without understanding the relationship of gravity to elementary particles we have no hope of understanding how the universe arose or what specific processes were likely to have occurred immediately after the Big Bang. That has consequences for cosmology, as well as for astrophysics.
History shows all mathematics eventually find some use in the real world, so you needn't worry that whatever physics you dream up will never have any application in the real world.
String theory has given rise to some truly gorgeous mathematics. Alas, it still hasn't made any predictions which can be disconfirmed by high energy particle physics experiments.
Current science appears to have gotten itself saddled with a number of degenerating research programs. AI, which has ground to a halt and been declared a lost cause by some of its leading practitioners; string theory; machine translation of human language; nuclear fusion; human space travel. All showed initial promise and then degenerated into dead ends with no progress observable in the past few decades. You have to wonder how many more decades these kindsof deead ends will continue to get funded. Perhaqs as long as phlogiston?
st cause by some of its leading practitioners; string theory; machine translation of human language; nuclear fusion; human space travel. All showed initial promise and then degenerated into dead ends with no progress observable in the past few decades. You have to wonder how many more decades these kindsof deead ends will continue to get funded. Perhaqs as long as phlogiston?
Posted by: mclaren | September 19, 2009 1:50 PM
NB click on my name and get a clue why.
Posted by: Ricky | September 19, 2009 2:32 PM
Naked Bunny with a Whip #5
The idea is that 4 dimensional being can see the entire 3D world without obstruction. Think of Square, you can see all of it. But a 2D person could only see the outer edges. Michio Kaku proposes that this allows for all sorts of fantastic technologies. Crazy, eh?
Posted by: Rory Kent | September 19, 2009 4:54 PM
here's Sean Carroll (from Cosmic Variance) laying out the case for dark matter better than I could:
http://online.kitp.ucsb.edu/online/lens06/carroll/
As an aside to all the MOND people - turns out, once you graduate from high school, being different for its own sake doesn't score you any extra cool points. Take that fact under advisement when deciding on your preferred unproven gravitational theory.
Posted by: dg | September 19, 2009 8:32 PM
to #22 RobMonkey - actually, my backgrond for the past 30 years has been in plant and agricultural research at the university level. although i haven't kept a list of specific articles on the "exact opposite" topic, your mention of H. pylori is, in fact, one of them. another was new observations and measurements of the planets in our solar system gleaned from the fly-bys of the latest satellite a few years ago. i am ont dissing research, which is my career interest, just the jumping to wrong conclusions that happens because people can't stand uncertainty.
Posted by: mv | September 19, 2009 10:59 PM
oh yeah, and i like to think i'm an English major, too, except when proven wrong by typos :)
Posted by: mv | September 19, 2009 11:04 PM
@NakedBunny: By simpler alternatives, I mean that string theory has neither unified everything nor does it even correctly predict what is already predicted. At the moment it's an unnecessary complication. There is the question of whether it can ever work - unfortunately we can't be sure until (a) someone shows it works or (b) someone proves it can't work.
There is nothing fundamentally wrong with the inability to lump gravity and electrostatic forces into a single equation; it may be as sensible as looking for an equation which predicts both the tides and the stock market. A useful theory which does unify things successfully must either make verifiable predictions not currently derivable from the existing models or else it must simplify something while retaining the predictive ability of all that's currently modeled; anything less than that is superfluous.
Posted by: MadScientist | September 20, 2009 6:47 AM
Tom, I sincerely hope that you do not teach your students stuff like this. In dumb-downed parlance (for my own benefit), theories can be viewed as explanations of facts (observations); they don't ever graduate into fact when the evidence reaches a certain level of proofiness. Theories change, but the facts that they explain do not.
Posted by: Zwirko | September 20, 2009 11:29 AM
From AWT follows, every theory, which expects Lorentz invariance and hidden dimensions at the same moment becomes inconsistent, because hidden dimensions manifest itself just by Lorentz invariance violation.
http://aetherwavetheory.blogspot.com/2009/02/consistence-problem-of-string-theory.html
Posted by: Zephir | September 20, 2009 2:17 PM
mclaren: "History shows all mathematics eventually find some use in the real world ..."
No, history shows just the opposite. Look at the libraries of the mathematical institutes: 90 percent of all publications have never found any use in the real world (most of them not even are used by any other mathematician), and this in the course of, say, the last 200 years (most mathematical publication have been published in modern times).
Yes, I know there are mathematicians saying "but any mathematical publication you take will eventually find some application in the real world, yes it will, if not in 100 years, then in 1000 years, or later". But those people don't have the smallest piece if evidence, if asked -- they just believe it.
Well, but the residual 10 percent are interesting and important.
Posted by: Duncan Ivry | September 20, 2009 8:42 PM
Zwirko: "Theories change, but the facts that they explain do not."
Take this: There is an upper limit to the velocity of material things. Theory or fact? Please, explain!
Before answering, please consider the following:
- Nowadays physicists say, that there is indeed an upper limit of velocity.
- Before Einstein they said the opposite.
- Because physical theories are falsifiable, we cannot exclude, that at some point in the future the theory of relativity, which contains a statement about an upper limit of velocity, will be falsified in this regard.
- Nowadays physicists say, that the statement, that there is an upper limit of velocity, has always been true and will always be true.
Irritated.
Posted by: Duncan Ivry | September 20, 2009 9:15 PM
Duncan, in those examples you give, the absolute facts never changed - our understanding of them changed. That there is a "cosmic speed limit" is what it is regardless of having people around to understand or measure it correctly or incorrectly at various points in history.
Likewise ancient peoples thought that the Sun revolved around the earth; now we know that it is the Earth that orbits the Sun. The truth was always that the Earth went round the Sun. That it was the other way around was never a fact, even though it was written down as such. Our understanding (theory) of why the Sun moves across the sky (observation) has changed.
The point is this: theories don't lie at one end of a continuous spectrum with solid fact at the other end and they don't turn into facts when the evidence comes in - they either get accepted, modified or scrapped.
When a fact (slippery word) turns out to be wrong, then it was really only an error in assuming that it was correct in the first instance. The underlying truth was always there waiting to be discovered.
Posted by: zwirko | September 21, 2009 6:46 AM
String theory predicts 10^500 different universes, all with different versions of quantum gravity and other physics. It therefore predicts more than any other theory, and is more important than any other theory. Besides, in physics it is heretical to question mainstream ideas, so you shouldn't. The important thing ow is fitting into status quo, not demanding unique predictions which are falsifiable. Popperian philosophy of science is old hat, and physics is now concerned with exciting ideas that make good sci fi films.
Posted by: nige cook | September 21, 2009 6:56 AM
ST does not predict gravity. It puts up a 10-d spin-2 Boson. Even in 4-d the spin-2 Boson is not GR, no matter how many times you say it is.
-drl
Posted by: D R Lunsford | September 21, 2009 7:08 AM
To reduce the possibilities, why not test these things by comparing the fractal dimension of various observations?
Posted by: LAnsbury | September 21, 2009 8:12 AM
"String theorists: We've got the Standard Model, and it works great, but it doesn't include gravity, and it doesn't explain lots of other stuff, like why all the elementary particles have the
masses they do. We need a new, broader theory.
Nature: Here's a great new theory I can sell you. It combines quantum field theory and gravity, and there's only one adjustable parameter in it, so all you have to do is find the right value of
that parameter, and the Standard Model will pop right out.
String theorists: We'll take it.
String theorists (some time later): Wait a minute, Nature, our new theory won't fit into our driveway. String theory has ten dimensions, and our driveway only has four.
Nature: I can sell you a Calabi-Yau manifold. These are really neat gadgets, and they'll fold up string theory into four dimensions, no problem.
String theorists: We'll take one of those as well, please.
Nature: Happy to help.
String theorists (some time later): Wait a minute, Nature, there's too many different ways to fold our Calabi-Yao manifold up. And it keeps trying to come unfolded. And string theory is only
compatible with a negative cosmological constant, and we own a positive one.
Nature: No problem. Just let me tie this Calabi-Yao manifold up with some strings and branes, and maybe a little duct tape, and you'll be all set.
String theorists: But our beautiful new theory is so ugly now!
Nature: Ah! But the Anthropic Principle says that all the best theories are ugly.
String theorists: It does?
Nature: It does. And once you make it the fashion to be ugly, you'll ensure that other theories will never beat you in beauty contests.
String theorists: Hooray! Hooray! Look at our beautiful new theory."
A great review by Peter Shor about the bokk "The Trouble With Physics", by Lee Smolin.
Posted by: Kata | September 21, 2009 11:44 AM
Fuck you dude.
Posted by: Stefan | September 21, 2009 11:57 AM
And one final quote by the Dutch physicist Gerard ’t Hooft, a Noble Prize winner for his work in elementary-particle physics:
"Actually, I would not even be prepared to call string theory a “theory” rather a “model” or not even that: just a hunch. After all, a theory should come together with instructions on how to deal with it to identify the things one wishes to describe, in our case the elementary particles, and one should, at least in principle, be able to formulate the rules for calculating the properties of these particles, and how to make new predictions for them.
Imagine that I give you a chair, while explaining that the legs are still missing, and that the seat, back and armrest will perhaps be delivered soon; whatever I did give you, can I still call it a chair? "
Cheers,
K.
Posted by: Kata | September 21, 2009 11:59 AM
To conclude, my quote: String Theory is the closest thing to "Religion"(perhaps faith) one can find in Sciences.
Cheers,
K.
Posted by: Kata | September 21, 2009 12:03 PM
To conclude, my quote: String Theory is the closest thing to "Religion"(perhaps faith) one can find in Sciences.
No testable predictions, no even tests for that matter...just believe IT! you gotta believe it !
Cheers,
K.
Posted by: Kata | September 21, 2009 12:07 PM
Unphysical pile of Garbage? That would be a complement compared to my feelings about String Theology. Since someone will ask, I received my bachelor's degree in Physics in 1968 (I am 63) and returned to grad school after serving as a pilot in the Vietnam war. I finally recived my PhD in Mathematics in 1987 with a dissertation entitled "The Geometry of Elementary Particles". That summer I went to the Summer Meeting of the AMS in Salt Lake City, where Ed Witten gave a series of talks on String Theory. I didn't know whether to laugh or cry, what he said was not physics, not even science, just speculation. My dissertation showed how to get matter out of the complex spacetime U(3,2)/U(3,1)xU(1).
And I did a lot more than Witten dreamed of. The problem is that one has to abandon a lot of what passes for physics these days. The no-go theorems can be by-passed using
U(3,2) instead of the Poincare group. QFT is not good science since it leads to infinities (and renormalization is nonsense). Einstein was not happy with General relativity because of the singularites. Quantum theory and GR are incompatible on at least 12 points, so a union is out of the question. One must trash both and start over. I had to abandon Lagrangians, and got more conserved quantities using the Casimir operators of SU(3,2).
Sting theory is Certainly Repulsive Anti-Physics.
Posted by: Thomas R Love | September 21, 2009 12:37 PM
Thomas and others
Would somebody please provide a complete list of the fundamental phenomenon that must be described/predicted by a QFT or a suitable replacement for QFT.
Posted by: Wes | September 21, 2009 4:29 PM
Thomas, I wish you could point out where to read this work.
-drl
Posted by: D R Lunsford | September 21, 2009 11:15 PM
Thomas, I can see the U(3,2) part but saying "I had to abandon Lagrangians" cannot be right, you might as well quit there, because any theory with conservation laws is going to have a Lagrangian formulation, period. So I can't imagine what you mean. One should not just rip away parts of the tested structure like this.
The referenced paper about where QG is going, makes a similar glib mistake, by taking Tmn;n = 0 as a conservation law (it's not).
-drl
Posted by: D R Lunsford | September 21, 2009 11:25 PM
If this stuff is true, then so few people would be able to understand it, the technological elite might be tempted to get rid of us dumb critters, justified by neo-malthusian Darwinism.
And as we all know, a theory that cannot be tested and validated by experiments is merely a hypothesis, not a theory. Some of this stuff was speculated on in pre-socratic times, call it philosophy, meta-physics, meta-religion, what have you, verified only by thought experiments, sober or not.
So many bright minds working on this, no wonder that since 1974 we seem to have hit a technological "Dark Ages" except for info-tainment technology and weapons/security systems.
They say it might take us 30 years to get back to the moon if we choose, but they also say it is too expensive. Since our monetary system is not much more advanced from the Dark Ages, thats not surprising. Today, like superstring theory, most of the worlds money is imaginary, it does not exist in any physical form except on hard discs as bits and bytes. In the Dark Ages the Templars used bills of exchange, they had no desire to go to the moon either, so no difference really.
So the only reason we don't have a space program is the lack of will to use imaginary money to finance it. I doubt superstring theory will solve that.
Posted by: pft | September 22, 2009 5:04 AM
http://www.springerlink.com/content/r630722r1pth4p47/?p=c3849ca55254464e8c7c3a3a97867c86&pi=0
http://www.springerlink.com/content/mtk1636062737125/?p=c3849ca55254464e8c7c3a3a97867c86&pi=1
These will take you to two of my papers (if your institution has a suscription.
drl said "any theory with conservation laws is going to have a Lagrangian formulation", sorry but you have been brainwashed by the establishment. The Casimir operators give conservation laws. Noether's theorem says that conserved quantities and generators of the Lie groups are in 1-1 correspondence. If you are working with a Lagrangian, a conserved quantity yields a generator, but nothing implies the existence of a Lagrangian.
Posted by: Thomas R Love | September 22, 2009 4:22 PM
Zwirko, you talk about "absolute facts", that "never changed", and about an "underlying truth", that "was always there waiting to be discovered". With all due respect, this sounds very much like religion and not like science. A crazy version of physics as ersatz-religion!
Posted by: Duncan Ivry | September 22, 2009 8:17 PM
TRL, there *is* no Noether's theorem without a variational principle behind it. I don't have institutional access, you could send the papers to antimatter33 at yahoo and I will investigate in detail.
In any case the theories that work - GR and spontaneously broken Yang-Mills - have Lagrangians and it would be silly to expect a better theory not to. But I will look, I promise.
-drl
Posted by: D R Lunsford | September 23, 2009 8:38 PM
It makes me sad to see scientists confused about what a theory is. A theory is not something to prove, or to disprove. A theory is any notion that generates / suggests / implies hypotheses. A usable theory generates testable hypotheses. A good theory generates hypotheses that turn out to be correct.
A theory can remain usable, and useful, after some of its hypotheses have proven false, if there's nothing better yet, or even if it's just convenient to use. After all, it can still generate testable hypotheses, and the outcome of testing them can still yield meaningful information.
String Theory is a theory, but it's not a good theory, and not even a bad theory, because to be one of those it would need to be a usable theory.
Posted by: Nathan Myers | September 23, 2009 9:57 PM
Doesn't string theory predict that there are extra dimensions and super symmetry.
Check.
Isn't the LHC going to be able to search for these.
Check.
What were people saying about string theory not predicting anything?
Now granted there are probably other explanations for these things if they are found to exist but doesn't it lend a little more credence to the theory if they are.
What happens if we don't find the Gibb's? does that mean the standard model is a pile of garbage, I think not.
Posted by: Doug Little
| September 24, 2009 11:30 AM
there *is* no Noether's theorem without a variational principle behind it---drl
Exactly, Noether's theorem limits the number of conserved quantities--making some problems unsolvable. I obtain far more conserved quantities using the Casimir operators (unfortunately, the standard theory of Casimir operators is wrong*). One of the problems I plan to attack with more Casimirs is the 3-body problem. My PhD advisor ar UCSC was Ralph Abraham, author of Foundations of Mechanics, which deals with the 3-body problem. If you have worked on it you know the trouble--not enough conserved quantities.
*Where mathematicians use Lie algebras, physicists use 'commutator gymnastics'---not the same algebraic operation and so not the same category.
Posted by: Thomas R Love | September 24, 2009 12:50 PM
sorry massive typo Gibb's = Higg's, don't know what I was thinking at the time.
Posted by: Doug Little
| September 24, 2009 1:12 PM
Can somebody here explain QFT to me with something like the set of axioms for nonrelativistic QM.
Posted by: wes | September 25, 2009 7:41 PM
Wes, It would take a book, the classic is:
PCT, Spin and Statistics, and All That by Raymond F. Streater and Arthur S. Wightman
Even then the axioms are not perfect.
Posted by: Thomas R Love | September 26, 2009 9:45 AM
Wes - Feynman's QED is nice relatively digestible discussion of Quantum Electrodynamics. It was written for an intelligent lay audience though it gets a bit rough near the end. My understanding is that QFT and QED are different ways of looking at the same subject. Both work however it is easier to apporach some problem with one or the other. There was a nice introduction to the version I read by a more current physicist in the field who discusses these issues, and how the popularity of QED and QFT has waxed and waned over the years (as in which was taught as an intro to the subject).
I have always been suspicious of string theory as it smacks of mathematical tricks to deal with infinities that sprung out of early attempts at understanding gravity. On the other hand, to dismiss it simply because is lacks any physical grounding would be a mistake. Feynman discusses in QED the fact that this is one of the most throughly tested areas of physics. As one earlier post mentioned, every test ever tried with it has confirmed it. And yet, you cannot explain in any reasonable physical terms why it is that the world at the quantum level works this way.
For instance, the idea that a photon travels on every possible path simultaneously cannot be understood in any physical way and yet you can prove it with QED or QFT by using a partially silvered mirror. There are any number of examples where the behavior predicted by QED/QFT seems impossible physically, and yet that is the way it is.
So string theory or some variation of it may yet turn out to be a way or explaining gravity. I hope I live long enough to see some of these questions answered.
Posted by: Mike Crooks | October 2, 2009 2:42 AM