On Strings and things…
(with thanks to Cat-eyes for provoking this interesting train of thought)
One of the biggest headaches in modern physics has been the utter incompatibility of two of our most imposing pillars of knowledge: General Relativity and Quantum Mechanics.
Einstein’s General Relativity beautifully describes the large-scale geometry of the Universe and shows that gravity is really the curvature of space-time in the presence of mass-energy. Meanwhile, Quantum Theory explicates the sub-atomic world as a frothy place where particles pop in and out of existence seemingly at random, but somehow balance out to produce the reassuringly ‘solid’ matter that we take so much for granted. The only problem has been that the mathematics of each these two theories completely break down and produce nonsensical answers when extended into the realms of the other!
Physicists have a high regard for symmetry and a certain ‘elegance’ when it comes to theories of ‘everything’, and this is decidedly a very UN-elegant state of affairs. While the math can get pretty hairy, the basic problem is simple: what happens when you divide by zero?… KA-BOOM!! <’Danger!… DANGER Will Robinson!‘>
One class of possible solutions to this conundrum has come to be called ‘String Theory’. Instead of point-like particles, sub-sub-atomic entities like ‘Quarks’ are envisioned as ultra-tiny* ‘string-like’ things, whose vibrational frequencies and harmonics produce the characteristics we previously associated with the zoo of sub-atomic particles. Immediate mathematical relief is to be had when these one-dimensional ‘strings’ replace zero-dimensional point-particles. No more dividing by zero!
As a musician, I must say that the image of cosmic vibrating ‘strings’ producing a veritable ‘symphony’ of ‘tones’ that in turn produce what we call ‘reality’ is a very attractive concept! I call it the theory of ‘The Big Note‘… ;-}
But this is just the beginning… as very smart people began to seriously apply the ‘string’ idea to the real world, they found that both Relativistic and Quantum effects fall quite naturally out of the theoretical framework! Eureka! But then, as things are so often wont to do, things got complicated again… It turns out that we needed 10 (count ‘em, TEN) spatial dimensions plus time for a grand total of 11 dimensions! YOWZA! And as if that weren’t bad enough, there are now things like ‘branes’ (from ‘membrane’) which are two-dimensional sheets of gossamer ‘stuff’. And there are several different formulations of string theory, only one of which can actually describe our Universe! Curiouser and curiouser!
The mathematical scaffolding being invented to describe such things is scary-hard. On a good day I can barely slog through simple differential equations, so the details are well beyond my humble abilities!
Happily though, Dr. Brian Greene has produced a very good book and a 3-part PBS/Nova special that explains things far better than I could. You can view the whole thing on-line here:
‘The Elegant Universe’
Recommended!
The Universe is not only queerer than we suppose, but queerer than we can suppose. – J.B.S. Haldane
* and I mean TINY! These entities exist at Planck scales (1.616252×10−35 meters). Sadly, we’ll probably never get to see a ‘string’!
I was going to say “or play one” but I guess we’re playing them constantly, occasionally even making beautiful music, or at least collaborating on it.
Gotta check out The Elegant Universe.
Comment on December 3, 2009 @ 7:24 am
This train of thought reminded me of a very old New Worlds post. Are you or Cat Eyes conversant in The Exceptionally Simple Theory of Everything?
Comment on December 3, 2009 @ 7:52 am
Max, I am familiar with Lisi’s E8 GUT theory. I remember the big splash it made in the press as well. While it is obviously an interesting concept ( also hard to envision ) it is still very early in the development stages. It predicts 22 new particles but the respective masses of these particles have not been calculated which is problematic. Even if the LHC finds new particles it can be problematic because of the unknown mass predictions. So in many ways it is a fuzzy as string theory in its predictive (or lack thereof) capacity. If 22 and only 22 new particles suddenly pop out that would lend strong support to the theory. Part of the problem is that the theory should try to predict the masses before test data is produced, because otherwise it is highly sensitive to the Texas sharpshooter biasing fallacy – in other words fudging things to make the theory fit the data – especially if there are less than 22 new particles found, which is highly likely that they will not all suddenly pop out.
Moreover, there are a few types of particles that if discovered would not fit Lisi’s model, but this is a good thing insofar as testability goes. Even though I believe Lee Smolin has been trying to find a way to explain these currently unexplainable particles in E8 theory, a sort of covering your ass before you know if you have to.
And if anyone thought that string theory’s 11 dimensions is crazy hold on to your seat because Lisi’s theory has more. It starts out with the 4 dimensional space time fabric but attaches the E8 lie group as a sort of fiber to it creating 248 further dimensions. Lisi separates the defining characteristics of the known particles by spin, directionality of spin, and charge in two directions, positive and negative, as well as mass, all with respect to gravity (on the base remember). It is kind of beautiful once you can sort of get your head around it. But then the same can be said for much of string theory.
Lee Smolin is one of the advocates for the E8 theory. This is in part due to research politics and funding. When string theory became the darling of the theoretical physics community, funding for other research became the needle in the haystack. But Smolin rightfully pointed out that string theory was not in any sense tested or definitive, much less predictive in any significant way when it was new on the scene. Smolin has had to fight tooth and nail for funding to support other research ideas. But he is correct. His theories may or may not be anymore correct but they do deserve as much exploration.
Much rides on what the LHC can do. We wait with baited breath.
Also Briane Greene has a follow-up book to the Elegant Universe called The Fabric of the Cosmos. Much of the material is similar but there are some new concepts introduced in it.
If you are really curious other books you should check out are:
1-Parallel Worlds: A Journey Through Creation, Higher Dimensions, and the Future of the Cosmos by Michio Kaku;
2-The Goldilocks Enigma: Why Is the Universe Just Right for Life? by Paul Davies;
3-The Life of the Cosmos by Lee Smolin;
4-The Trouble With Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next by Lee Smolin;
5-Three Roads to Quantum Gravity by Lee Smolin;
6-Warped Passages: Unraveling the Mysteries of the Universe’s Hidden Dimensions by Lisa Randal;
For a blog entry that introduces some of the problems see:
The Dynamic of Cats at http://scienceblogs.com/catdynamics/2007/11/red_boson_blue_fermion.php
You should check out that blog anyway – just because it has the coolest name. But also you can find tons of great into at scienceblogs.com – lots of categories on a plethora of topics.
For a very heavy and detailed Physics of the Universe today refresher kind of book see The Road to Reality: A Complete Guide to the Laws of the Universe by Roger Penrose.
Hope that helps Max.
Comment on December 3, 2009 @ 12:15 pm
Wonderful wonderful. Thank you very much for the great context. I’ve got a lot of questions for my Muon-adventurer buddy Robert next time I see him.
I have to take issue with this, though:
Anything less that a thousand dimensions is so 21st century. Let me know we get into something a little less blasé, say the million dimension models…
Comment on December 3, 2009 @ 12:23 pm
By the way, thank you Sky for the great animated graphic.
Comment on December 3, 2009 @ 12:25 pm
Wow… quite an invigorating back and forth on these heady topics! If an unwary e-tripper were to happen upon this site, they might even think we knew what the hell we were talking about! (rim-shot… splash!)… but I kid the Universe… ;-}
Seriously, folks (snare… [wait for it...]… SPLASH!)… No really! c’mon! …
I’m glad Cat-eyes liked the animated 24-cell (also called an icositetrachoron… try saying that quickly three times)… I found it on Wikipedia while I was checking some of my facts. It has nothing whatsoever to do with string theory… But it DOES have a certain extra-dimensional look about it and I just thought it was kinda cool! ;-}
I’m gratified to be able to correspond with such clever fellow seekers! Cat-eyes’ erudition is blowing my mind and forcing me to bring my ‘A’ game… and thanks again to Max for setting up the site in the first place… and to byronius for hipping me to it. It’s nice to be grazing again amongst my sheepish pals in the e-lotus fields! Let’s face it, these aren’t subjects I get to argue about at the bus-stop or the local pub… So my thanks to you all!
Now (ahem), where was I? Oh yes… I need to do some homework before I can argue intelligently about “An Exceptionally Simple Theory of Everything”, but while E8 lie-algebras may be ‘exceptional’, they are certainly anything but ‘simple’ (I get the pun though)…
Cat-eyes briefly raised a point re: Lee Smolin that deserves some amplification; that being the ‘politics of science’. While we’d like to believe that in the rarefied world of Theoretical Physics, such mundane issues as politics are non-existent (the image of the serene and über-brilliant Ed Witten comes to mind), nothing could be further from the truth! In academia as elsewhere, it’s always and forever about FUNDING! String Theory and E8 GUT’s are good examples… When Strings hit serious snags in the late 1980′s, funding dried up and many workers went back to the tried-and-true particle world. Likewise, many good brains are loathe to get into E8, since it may well turn out to be yet another chimera… Science is a very human endeavour, subject to all the petty jealousies and flaws we know all too well. The saving grace of Science, and what makes it an infinitely more powerful tool of inquiry than theology or general philosophy is that it is SELF-CORRECTING. Science is from Missouri! Show Me!… now show me again… and AGAIN!
Another good point that Cat-eyes raises is related… is ‘String Theory’ really a THEORY at all? As I mentioned earlier, the postulated ‘strings’ (open or closed loops) and ‘branes’ are so tiny that we’ll likely NEVER have a way to really ‘prove’ that they exist… they are really MODELS that we create to think about things. But any proper theory must make PREDICTIONS about the world that can be TESTED and objectively proven or refuted. So far (as I know), there is a dearth of predictions from String Theory. So while it DOES neatly explain many known phenomena, that’s not quite enough, is it? This is why some theorists bridle at strings, calling it ‘mere’ philosophy… and who knows, they just may be right! We just don’t know yet. I guess the moral is to keep an open mind, but not so open that your brains spill out! (ICK!)
Finally, here’s a thought that occasionally keeps me up nights (or days… they get mixed up)… How is it that semi-evolved African primates just recently off the savannah have any business figuring out how the fucking UNIVERSE works in the first place?! Our arrogance is really pretty stunning when you think about it. And I don’t buy the ‘anthropic principle’ since it is a circular argument: we’re here because the universe is designed(?) to be a place where we can be here because… Nope. That cuts no ice with me. My best guess is that our brains got fancy enough to begin to produce SYMBOLS. Once one thing can ‘stand for’ another thing… well the game is suddenly entirely different! Suddenly we get Language and Art and Machines and Music and… blogs. I suspect that our big brains were evolved to allow us to have complex relationships within social groups… we learned (in effect) to ‘read minds’ in order to MANIPULATE and PERSUADE those other minds (to our own ends)… ‘Playing’ these various ‘what if’ scenarios in our heads is perhaps not such a big leap from inventing SYMBOLS… and thereby, true MINDS…
Just sayin’…
Comment on December 3, 2009 @ 3:34 pm
Ah yes, correct on many fronts. Social behavior is the best guess at what environmental factors saved the random mutation that accidentally gave one of us a big brain. As an aside here I’d like to point out an overlooked and under-appreciated necessary component of such an event. The mother. She probably died in childbirth since even now such big heads are not well suited to the birthing process. If she did not, then she was likely already some kind of mutant. But that kid must have been really something. Who knows many that kid was the one who made the first stone tool and started trying to figure out fire.
But back to the topic, another study or perhaps a kind a meta-study (1999 or so) studied how scientists worked in the lab. The results were somewhat appalling.
(the following is anexcerpt from the Frontal Cortex blog . . .
Kevin Dunbar is a scientist who studies how scientists study things –how they fail and succeed. In the early 1990s, he began an unprecedented research project: observing four biology labs at Stanford University.
Dunbar came away from his in vivo studies with an unsettling insight: Science is a deeply frustrating pursuit. Although the researchers were all using established techniques, more than 50 percent of their data was unexpected. (In some labs, the figure exceeded 75 percent.) “The scientists had these elaborate theories about what was supposed to happen,” Dunbar says. “But the results kept contradicting their theories. It wasn’t uncommon for someone to spend a month on a project and then just discard all their data, because the data didn’t make sense.” Perhaps they hoped to see a specific protein but it wasn’t there; or maybe their DNA sample showed the presence of an aberrant gene. The details always changed, but the story remained the same: The scientists were looking for X, but they found Y.
here were models that didn’t work and data that couldn’t be replicated and simple studies pockmarked with mistakes. “These weren’t sloppy people,” Dunbar says. “They were working in some of the finest labs in the world. But experiments rarely tell us what we think they’re going to tell us.”
How did the researchers cope with all this unexpected data? How did they deal with so much failure? Dunbar realized that the majority of people in the lab followed the same basic strategy. First, they would blame the method. The surprising finding was classified as a mere mistake; perhaps a machine malfunctioned or an enzyme had gone stale. “The scientists were trying to explain away what they didn’t understand,” Dunbar says. “It’s as if they didn’t want to believe it.”
The experiment would then be carefully repeated. Sometimes, the weird blip would disappear, in which case the problem was solved. But the weirdness often remained, an anomaly that just wouldn’t go away.”
This re-iterates my point, and the point Sky has expanded on. Scientists are humans. Humans are screwups by in large and hate to admit it. But that’s why open peer reviewed papers that include all methods and ALL data is the only way to keep science healthy. And why it is in part so important to keep corporate entities out of it. The transparency that makes science reliable is jeopardized when the bottom line pundits use white-out on negative, neutral, conflicting, questionable, or even marginally good data.
And here’s Richard Rorty: (Philosopher for those who don’t know who he is).
There is no reason to praise scientists for being more ‘objective’ or ‘logical’ or ‘methodical’ or ‘devoted to truth’ than other people. But there is plenty of reason to praise the institutions that they have developed and within which they work, and to use these as models for the rest of culture. For these institutions give concreteness and detail to the idea of unforced agreement.
Which brings me to another point. There are certain factions that like to call science a kind of religion. This is inaccurate. It is another institution but not like religion. Religions are ego-centric, by people, for people, its us, us, us, me, my, mine, ours, etc. But science as an institution doesn’t really give a crap about us any more than anything else. It is not about making us happy or putting us at the center of anything – the complete opposite of most religions.
Religion has failed as an institution for more than one reason, but mostly because if people are involved with imaginary things there will never be global consensus. Religion wants/requires certainty.
Science on the other hand since it deals with evidence, can succeed despite our differences, and often actually thrives because of those heretics that question the existing beliefs. Uncertainty is the hallmark of all science.
Comment on December 3, 2009 @ 4:20 pm
Sky relieving the stress of imperfect data.
Comment on December 3, 2009 @ 5:38 pm
TEE-HEE! And dig those way-cool shades! (not to mention a forehead that goes on forever!) Clearly, this is one highly-evolved primate! ;-}
I find no error in Cat-eyes’ logic. Our brains clearly are resonating in harmonic convergence! ;-} oh WOW man… that’s soooo HEAVY…
On the problem of big human brains in the birthing process… It is a sad but true fact that human women have an awful time giving birth to the next generation (I can hear my ex saying ‘if you only KNEW, buster!’ ;-+). Without modern assistance, as many as 1 in 5 women commonly die in childbirth… pretty lousy odds. The pelvis can only be so wide and still be capable of decent locomotion…. although I’m quite partial to the female style of locomotion… but that’s another conversation entirely! ;-}
Anyway, our giant brains clearly have been shown to have a selective advantage… so evolution has found some adaptive tricks:
Human children are born prematurely. We’re ALL ‘preemies’! So our brains do a good part of their growing OUTSIDE of the womb. The downside to this of course, is that human infants are utterly HELPLESS for an extended period of time. We also exhibit a kind of ‘arrested development’ in many features. The word for this is ‘neoteny’ and it goes a long way toward explaining both our lack of body hair and our retention of fairly juvenile features well into adulthood (a baby Chimpanzee looks FAR more ‘human’ than does an adult). And recent studies of the dentine growth on Homo Erectus and Neaderthal teeth have shown that they grew up much faster than we do! The famous (homo Erectus) ‘Turkana Boy’ was quite tall at about 5′ 8″ and was thought to be about 12 years old. From his dentition, we can now estimate that he was only 8! So not only are we moderns born too early, we also take a LOT longer to grow up… partly in order to give us extra time to learn how to USE our big brains no doubt!
Clearly, a woman nursing a completely dependent new-born is of only limited use in a hunting-and-gathering role, so our social structures changed to encourage a division of labour between men and women. We also tend to be much more monogamous than our primate cousins. Pair-bonding allowed the female to care for children while she could reasonably count on ‘her’ man to bring home the bacon (as it were). This sort of behaviour may have had something to do with us getting up on two legs in the first place, enabling us to CARRY said bacon back to the clan…
We moderns have in some ways stepped off the ‘treadmill’ of evolution, so please don’t construe these comments to be a reflection of my attitudes bearing on female ‘equality’ issues!
Comment on December 3, 2009 @ 5:56 pm
Mixed divisions above.
count on ‘her’ man to bring home the bacon (MEN???)
to CARRY said bacon back to the clan
I think in hunter-gatherer groups it is always about the clan when it comes the food, so as long as any of the men bring something home it’s good for everyone. No one goes hungry, you just get your choice of the prime cuts if you bagged the bacon – so to speak. Moreover, it’s been demonstrated that the bulk of the food is from gathering by the women, and that food constitutes the bulk of the variety in the diet that provides for a balanced nutrition in the vast majority of cases.
Comment on December 3, 2009 @ 6:55 pm
Yes, the clan is primary. But the ‘exclusive’ pair-bonding adaptation must have bestowed SOME selective advantage else it wouldn’t have happened! There were certainly advantages to being paired up with the ‘chief’ or the best hunter or the clan shaman to be had: “How would you like your steak ma’am?” However, monogamy has certainly proven over the millenia to be awfully problematic (for both sexes), so I won’t press that argument any further!
You are also correct about women and the ‘gathering’ part of hunting-and-gathering. Truth be told, most hunts come up empty, and in many tribal cultures it sure seems that the guys seem to lay around a lot while the women do most of the real work…
I’m not quite sure what that ‘means’ in sociological terms but I must admit that it brings the image of the beer-swilling couch-potato to mind…
(belch!)
mea culpa! ;-}
Comment on December 3, 2009 @ 7:16 pm