Elegant Universe Airs Tonight on PBS

fatarfy writes "USA Today among others has an article discussing tonight's presentation of Brian Greene's Elegant Universe, which discusses String Theory. It airs on PBS. From the article: 'The two segments of the show turn their spotlights on a crisis in physics, one invisible to the general public but increasingly embarrassing to the discipline. Simply put, Einstein's unbelievably accurate explanation of gravity, known as general relativity, is completely out of whack with the equally accurate explanation of electromagnetism, radioactivity and atomic forces known as quantum mechanics. The theories are mankind's most fundamental views of verifiable reality, and the disagreement means that something important about the universe eludes our understanding.' Sounds like it's worth watching."

Comments

For sure, more than one thing *grin*

[Futurepower(R)]

"... something important about the universe eludes our understanding..."

Exactly correct, but also unintentionally funny. I'm guessing something is more accurately 100,000,000 things.

classical/statistical - quantum reconciliation

[Doc Ruby]

At least one physicist, Garnet Ord, has extended the classical/statistical physical model of phenomena to include quantum mechanics. Perhaps similar work with Relativity can produce a grand reconciliation?

String Theory

[Academy Girl]

The thing I find funny about critics of string theory is their objection to the idea that there can be multiple dimensions beyond the three dimensions people can perceive. This is where philosophy and physics should intersect -- right at Kant, who pointed out that you cannot understand the world, only your perception of the world. Now, whether or not you agree with Kant, the point is that you, at least, shouldn't be limited by your perception of the universe. It seems plainly obvious that just because people can only perceive three dimensions, the universe certainly doesn't have to be contained by that premise.

Re:String Theory

[citoc]

The issue isn't the inability to understand higher dimensions, most critics have an issue with the inability to observe higher dimensions. If higher dimensions exist, why don't we observe things moving in them? The only reason String theory predicts higher dimensions is because the matrix it uses (the math kind not the movie kind ;-) can only be solved in higher dimensions. So the explanation that these higher dimensions must in fact exist on a plane smaller than our observable limit (roughly a proton) seems a bit arbitrary to some (many).

Surely we can agree that the gap between quantum and relativity needs to be filled, but going off on a whole set of random assumptions based on what needs to be true to solve a little math issue might not be the best approach. Then again, look what it did for Einstein... Of course the difference there was that his predictions were actually observed...

Re:String Theory

[Bootsy Collins]

The thing I find funny about critics of string theory is their objection to the idea that there can be multiple dimensions beyond the three dimensions people can perceive.

Who fits that description, though? I know lots and lots of theorists in elementary particles and fields who are critics of string theory, but not for that reason. Indeed, it'd be odd if so, since mainstream particle theorists have been building models incorporating additional "dimensions" since the 1950s (e.g. isospin models in particle and nuclear physics).

The real criticism of string theory is much more fundamental. In order to be taken seriously -- indeed, to even be considered scientific -- a physical theory should be falsifiable. There should be some experiment I can do or observation I can make where, if it doesn't come out the way the theory says, then the theory is wrong. But since string theory describes the nature of things at energies around the Planck scale -- 19 orders of magnitude greater than the mass of the proton, or 16 orders of magnitude higher than the best particle accelerators we've built -- how do you test the theory? String theorists say that they simply haven't been clever enough yet to figure out how to make unique predictions at potentially experimentally accessible energies, but that they will be; and maybe they're right. I hope they're right, because string theory is beautiful in a lot of ways (at one point, I wanted to do string theory). But they've been saying that for 20 years now, since Green (no relation), Schwarz and Witten's stuff.

Re:String Theory

[jazman_777]

In order to be taken seriously -- indeed, to even be considered scientific -- a physical theory should be falsifiable.

Unless, of course, it happens to be _true_.

Re:String Theory

[Bootsy Collins]

> In order to be taken seriously -- indeed, to even be considered scientific
> -- a physical theory should be falsifiable.

Unless, of course, it happens to be _true_.

I'm not sure whether you meant this reply as a joke or not; the moderation suggests so, and perhaps my humor detector is even worse-off than it usually is. But it seems possible to me that your reply is serious, so (being both a physicist and an educator) I can't help myself . . .

Perhaps the most widely misunderstood property of modern science is that no proposition, no scientific theory, is ever proved to be absolutely true. No matter how much evidence you accumulate in favor of some theory or model, there's always the possibility that next week someone's going to come up with an experimental or observational result that requires that theory's revision or even outright rejection. Scientific theories can only be proven false; they can never be proved true.

"Yeah, yeah," you might be saying, "but I wasn't talking about whether theories can be proved true or not; I was talking about whether or not a theory actually is true. After all, even if we can't ever know with 100% certainty that a particular theory is true, it may still be true." Yes, indeed. But that's irrelevant to my original point, the one to which you replied. Since we cannot ever know with certainty whether any theory we put forward is absolutely true, and thus any theory is always subject to scrutiny, our requirement that the theory be falsifiable -- that it be possible to conceive of an experimental or observational result which would rule the theory out -- still stands.

Re:String Theory

[key45]

I heard Greene on NPR's Science Friday He says that some recent work on the theory predicts some effects which may be testable in a few years by the newest generation of "atom smashers" currently under construction at CERN and elsewhere.
We may get to that "falsifiable" stage relatively soon...

Re:String Theory

[Bootsy Collins]

I heard Greene on NPR's Science Friday He says that some recent work on the theory predicts some effects which may be testable in a few years by the newest generation of "atom smashers" currently under construction at CERN and elsewhere.
We may get to that "falsifiable" stage relatively soon...

Unfortunately, I'm not so optimistic. At least, not in general.

To explain why . . .in string theories, one of the things that has to be explained can be oversimplistically described as "where are all the other spatial dimensions now?" Why are three spatial dimensions macroscopic (effectively, observable by us) and all the others not? In the very early universe/at extremely high energies, all the dimensions should have been equal; but somehow, three of them expanded into the universe we know while the others stayed small. How this is done mathematically is referred to as "compactification" (and for anyone out there who's a math graduate, it's the same compactification of manifolds as you encountered in topology).

Some string theories have, as a result of the compactification, one of the compactified dimensions actually being comparatively large, with a characteristic scale of about a millimeter or a micron or something like that. These "one large dimension" models look like they would have observable consequences for experiments at accessible particle accelerator energies; and so it's possible that such models could be falsified. But that's not the same as falsifying string theory; it's only the possibility of falsifying a class of models within string theory.

Re:String Theory

[squiggleslash]

Apparently most washing machines are four dimensional objects, which is why you keep losing socks in them.

In order to balance, one of the two opposing socks is pushed away from the other in the unseen plane, balancing the washing machine but, regretfully, making that sock unobtainable. Many scientists believe that at the opposing side of the washing machines is a large black hole, into which the socks go, which in turn is unbalanced as a result causing each sock to remove a small amount of mass from the hole on entry.

This is why you get holes in your socks. It's symmetry.

Re:String Theory

[mrgeometry]

http://mathworld.wolfram.com/Calabi-YauSpace.html

The above-linked page has a rough definition of the kind of space a 10-dimensional string theory might live on. I don't know why they take a product $M \times V$ --- why not allow a more general bundle of C-Y 3-folds?

The imaginary version of string theory which exists only in my mind has the universe as a bundle of Calabi-Yau 3-folds over $M$ (a real 4-manifold with a Minkowski metric, or something like that... anyway, a $(3,1)$ form --- that's a Minkowski metric, right???). That's 10 dimensions. The 11- or other-dimensional kinds of string theory, I have no idea.

Being an algebraic geometer (in training), I think of a C-Y 3-fold as a smooth projective complex 3-dimensional variety, or manifold, with trivial canonical bundle.

Well, that's the space. Then all kinds of crap happens *in* the space, with strings and stuff, and that's a whole nother story...

Re:String Theory

[mrgeometry]

I'm stupid. I meant to say also the following. What if we specify an ample line bundle L on the C-Y 3-fold X; this is a polarization of X? Ample in algebraic geometry is the same as positive in several complex variables.

Among other things, this gives a *volume* of X, a positive real number, which is the same kind of volume that we're used to thinking of---like a cube with sides all equal to 1 has volume 1, etc. The Griffiths and Harris book would explain this better than I can.

The volume is something like $L^3/sqrt{2\pi}$, or something like that. Since it's physics, there are some kind of units. If this volume is small enough (i.e. measured in small enough units), it might suggest a reason why we can't move "along" the six dimensions corresponding to the C-Y 3-fold bundle: something small like an electron already fills up the tiny volume.

Ah, whatever. I'm just talking out my butt.

Re:I'm busy tonight

[NanoGator]

"Some record it and put it on Kazaa for me."

If the television industry were to be a little more forward thinking, they'd do that themselves. They'd put a few commercials in, get paid for it, and it'd be distributed virtually for free. If they maintain a server to make those shows availble with a decent download rate, then they can pretty much insure that nobody's going to edit out the commercials. (If they wanted to be real assholes, they could use Microsoft's Media format and disable indexing on it, thus meaning you can't skip commercials.)

embarassing?

[TwistedGreen]

The two segments of the show turn their spotlights on a crisis in physics, one invisible to the general public but increasingly embarrassing to the discipline... general relativity is completely out of whack with the equally accurate explanation... known as quantum mechanics.

How is this an embarassment? It's a fascinating puzzle to have uncovered! Once we nix this dilemma, we'll have the most comprehensive understanding of the physical universe ever before achieved! But it's embarassing that we've already gotten this far? Whomever thinks that does not have an accurate understanding of the nature of science.

If you already plan to watch Nova...

[node 3]

Don't try too hard to find "Brian Greene's Elegant Universe" in your local listing. Instead, just watch Nova as planned, as that's the show which will be covering the topic. Part one is tonight. Part two is next week.

I don't know why the article (at least), or the headline (even better) didn't mention this. It's sort of the inverse of "The Lone Gunman are Dead".

Yes, it's in one of the seven links. Did you click all seven? I didn't.

Re:I'm busy tonight

[DJayC]

Actually, PBS is allowing you to view the program on the website after both airings. (this week and next week)

From the site:
"Immediately following the broadcast of "The Elegant Universe" on October 28th and November 4, watch the entire three-hour special here. Each episode will be divided into chapters and can be viewed with the QuickTime or RealPlayer plug-ins. "

And the link:
http://www.pbs.org/wgbh/nova/elegant/program.html

More information

[daigu]

It's a bit dated, but this bibliography has some of the more interesting works in the field.

Re:I'm busy tonight

[anthony_dipierro]

We're talking about PBS here. It's really easy to skip the commercials already, since they're not embedded in the program.

Of course, if they offered it for download on the internet, they wouldn't sell as many DVDs for $20.

Whatever, my tax money is already paying for the program. Please, someone record this and put it on Kazaa for me.

book; better book

[bcrowell]

I guess I'm just an intellectual snob, but I can't see tackling a difficult subject like string theory by watching a TV show. The thing that always bugs me about TV is that I can't turn the page when I want to, either forward or backward!

The TV show is based on a book of the same title, which I've read. I don't think it's the best introduction to the subject of quantum gravity, because it's all predicated on string theory, which is only one possible candidate for a theory of quantum gravity. Actually string theory has made essentially no progress in the last 20 years. You still can't calculate anything with it, it still doesn't make testable predictions, and there are still too many different versions of string theory, with no way to tell which (if any) is correct.

A much better book is Lee Smolen's Three Roads to Quantum Gravity. What I like about it is that it focuses on basic principles of what a theory of quantum gravity must be like, rather than just describing all the (probably incorrect) details of one (probably incorrect) theory. Before reading Smolen's book, I'd also recommend starting off with QED: The Strange Theory of Light and Matter by Feynman, which describes the relatively well understood unification of quantum mechanics with special relativity (as opposed to general relativity).

Re:book; better book

[Curtman]

I don't think TV is a great media for exploring a subject, so much as it is great for presenting you with an overview of what something is about. I've tried many times to read physics books and tire of them pretty quickly because I don't understand some underlying principle. I need lots of pictures and naration to handle these concepts. Thanks for the suggested reading, I think this series will be enough of a snapshot to prompt me to pick one of these books up and actually get through it.

Re:book; better book

[MysticGlyph]

I also have read extensivly on the subject of string theory. I found the PBS program to be VERY helpful in laying out difficult to understand concepts and actually making things understandable to the laymen, or armchair (wannabe) physicist. Another great source for string theory information is at http//www.mkaku.org ...and Michio Kaku's book "Hyperspace" is a fun and informative read, I highly suggest it for anyone interested in learning more about string theory.

Re:"equally accurate"

[barawn]

Er? QED is arguably the most accurate theory - something like what, 11 different measurements of alpha yield the same result to 10 digits or so? (I want to say that this is in Peskin & Schroeder's Quantum Field Theory, but I could be wrong). However, for one, that's only QED, not quantum mechanics in general. It's not like QCD is well tested - at all.

And, for two, it depends on what you mean by "accurate". Certain portions of GR - for instance, the equivalence principle - have been tested ridiculously accurate - 1 part in 10^12, or something like that. Plus, if memory serves, the binary pulsar measurement was ridiculously good in agreement.

QED is by far the more accurately tested theory of the two. By *far*. But if you group all quantum field theories together, then it's not so good (because strong strong interactions are just as hard as gravity), and "quantum field theories in general" start to look about as accurate as general relativity.

I think the basic idea is that QM and GR are fundamentally different theories. You look at them, and it sounds like you're talking about two different Universes, with two different physical laws. And the problem is, that within the domain of their accuracy (GR is large-scale, 'strong' gravity, QFTs are generally short-range 'weak' interactions, but only because the long range stuff is classical) they're both extremely accurate - about as accurate as the measurement can make. And the main problem is that no one has a friggin' clue how to unify the two.

Well, they have a clue. It's just that most of the time, that clue makes the universe look like a complete disaster. It's like in the 1930s, during the revolution in particle physics: "who ordered THAT?"