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Author Topic: Groupthink and Physics
Stradling
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I haven't read Smolin's book (disclaimer). This is going to be long but worth it (disclaimer 2).

Since I grew up around physicists (Los Alamos) and have been getting my PhD in a part of physics related to string theory, I can speak to both the technical and social aspects of your groupthink assertion.

Item 1 - Theoretical physics is a small part of the physics community. High-energy theorists are a moderate part of that group. String theorists (note the name) are a small (though growing) part of HEP (high energy particle physics) theory. It is not persuasive to state that physics has been taken over by string theorists. Certainly, experimentalists are not big fans yet - there's nothing for them to do there. [Smile]

There is no indication that the rest of the theoretical community is being encroached on - there are many, many people who work on other, more immediate issues. More on that later. There is a comparatively large amount of hiring going on in string theory - because lots of people are VERY interested in some aspects of it. However, the hirings tend to be shared between physics and math departments (obviously) because there's some ambiguity as to who will eventually be left with the results. "Here" at UW Madison, there was recently a cluster hire of three string theorists, one from math and two from physics. That's a 10% effect on the number of THEORISTS in the department. It was considered a big hire.

Item 2 - Doing the math is not as easy as you make it sound. When you actually manage to do the math, it means a lot of the underlying problems have been solved - you've already done a large part of the "debugging" and your description doesn't spiral off into nonphysical infinities.

quote:
But the key mathematics, the reality check, had only been done to the "first approximation," which meant that nobody had any idea whether any of this stuff actually described the real world.
Do you have any idea how hard it is to get past a first approximation? Newton got famous on his first approximation. The real world, even on our scale, quickly dissolves into a nightmare of mathematical difficulty. Every keystroke I make, every eye twitch, every elbow jerk, is described by infinities of derivative terms cascading out into the black. We handle that complexity by chopping things off when we have enough precision or not enough time to do the calculation. If a first-order is enough to go with, we use it and try to find clever ways to get more orders to fall out without infinite labor.

We can't actually solve most things in physics precisely. We can approximate, sometimes well. But it's hard. The only interesting problems we have "exact" solutions for are the simple harmonic oscillator and the hydrogen atom. And even hydrogen is more complex than we give it credit for (that why it's "exact"). Helium is just another electron and proton - and we can do nothing exact. No perfect equations. Just approximations - modifications of the hydrogen atom as a starting point. And, of course, there are no real perfect simple harmonic oscillators.

quote:
Especially Physics. Because physics is the field of Newton and Einstein. Physics describes the real universe, at its smallest and largest scales -- from quarks to quasars.
Physics is where you realize that nothing will ever be easy - because as we get more and more "fundamental", things get less and less deterministic. Oh, well. And, by the way, the quarks to quasars line encapsulates just why string theory is so exciting, for all its impracticality.

quote:
Everything in physics is predicted through mathematics, and then checked against the real world. It is the purest of sciences.
Ahem. Not really. It *is* the purest of sciences - but as you should know by now - if it's real, there's always a catch. Math (and associated semantics) are also impure, but are by definition as pure as they can be. See Gödel. In physics, we see the world and try to describe it repeatably - because then we can do something with it. The rare and sweet exception is someone taking the next step and showing something mathematically that is later seen in an accelerator or something. It's a turning of the tables, and it's hotly pursued.

If we build a model that works with our data and then it works with someone else's data as well, then we have a success. That's usually how physics works.

quote:
until it now dominates the field of physics so thoroughly that it is only just barely possible to point out that it is not proven and probably is not true.
Have to call baloney on this - categorically not true. If Smolin made this assertion, he's suffering from limited vision. String Theory's lack of provables is regularly discussed and often mocked, even by its practitioners.

Why, then, is it so attractive? Why do people "waste" their time and other people's money doing it?

Quasars and quarks are nasty things to study - we can't probe them directly, or isolate one in a lab. We do our best, though. The very large and heavy (quasars, black holes) we deal with in general relativity. Quarks and leptons we do with quantum theory - or more generally, the Standard Model of particles and fields.

They don't match. They explode on contact. They contradict each other - and at least one is therefore cockeyed wrong.

Except that they both work on all the scales that we can probe them on. Too bad those scales are so widely separated. [Smile]

String theory as math is lovely. As physics, it's crap, for now. It's also the only viable candidate that people have to play with that spans the contradiction between large and small. Smolin is a player in the field, and has proposed several others, all of which are appealing - but if people don't have room to play in them, not much they can do. That, and none of them have any results to back them up either. [Smile]

So - when you have nothing that works, you might as well fool with the most promising candidate to see if you can make it work. Maybe it's just over this hill, you say to yourself. That works sometimes (Brigham Young), but not always (lost hiker).

quote:
We even have leading String Theorists saying, in effect, "Because String Theory gives us no way to describe why the universe functions as it does, we can only conclude that the universe we live in is a random event. We happen to live in the universe that happened to produce physicists, and so all we're studying is the accidental rules of this universe, when there could just as easily have been any of a million -- or an infinite number of -- different rule sets that were just as valid."
Not at all. What they're saying is that they have so many undetermined parameters in their theory that we don't know why the universe would have turned out as it did. Par for the course with mathematics.

Physics (especially HEP) has the same issue. Right now, my group is working on how to find a Higgs particle. It's hard, because there are two undetermined parameters, and that means we're not looking for a bead on a string, but for a specific grain of sand on a beach. Takes a lot of looking. When we find it, we will be able to nail down several undetermined parameters in the Standard Model - which has a lot of free variables as well. Lucky for us, they're measurable in our energy regime. Otherwise, it's be like string theory, and by tweaking any of them, we could describe a multitude of universes as well - places where photons are heavy and slow, etc. It's just that we have a crib sheet.

Think of theoretical physics as a community of fiction writers. Most are there to have fun and make a living. They try coming up with the next Great American Novel. They want to describe something True.

Some are like Danielle Steele - they use formulae with some skill to produce papers and explorations of not-particularly-interesting subjects. Some take the James Joyce route - obfuscation with bits of genius hidden away. Every once in a while, we have a Tolkien that spawns a whole new form that people are VERY attracted to and put a lot of themselves into, and which might contain some Truth. Sometimes we have a Shakespeare that describes Truth, and is proven beyond doubt to be Right.

I'm sitting here at CERN where a truly gigantic accelerator is being built to poke around and see if we can find some data for supersymetry and strings and general relativity and technicolor and Loop Quantum Gravity (Smolin's baby) and others. Possibly we find something that proves one theory and discards others, and leaves still others untouched. Hopefully we find something truly new. In the mean time, ALL the theoreticians are waiting and speculating at the top of their lungs. [Smile]

Meanwhile, the whole Rest of Physics (a *very* conservative field) moves on and pays passing attention to this whole drama.

There's a lot more to say, but I have work to do.

I know Groupthink exists in all disciplines, and the concentrates in the humanities in particular (because it can be gotten away with). I know that there is some in my field. But in fields that have to deal with reality, there are corrective mechanisms. When people are shown to be wrong, they are wrong. Done. They have to get up and move on, usually. Fortunately, there are lots of things to see and do. There are individuals that resist - and the stream flows on around them.

If String Theory gets some experimental support, it'll be fun and cool. If not - when the attraction goes away, the people who studied it don't die or get fired - they just go find something else to look at and prod. This has happened MANY times in physics in the last few centuries - it's how things go.

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Everard
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Brilliant brilliant post. You should post this on hatrack where card will see it [Smile]
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jouissance
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Seconded- Cut and paste this over there. Very nice!
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Stradling
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I actually mailed it to him direct. [Smile] But I'll Hatrack it too if I see a thread that it fits.

Thanks, Ev. [Smile]

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javelin
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I have to add my applause too. Yay!
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frogcat2
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Nice post. Thanks!
The NY Times has a similar article by a professor of physics and mathematics.

Universe on a String

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danshawen
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Congradulations on finding the Higgs boson!

Judging by the increased frequencies of the citations about Higgs and gravitons, even on IOP (Higg's own organization), something really big is in the works. Higgs isn't a graviton, exactly, but there are ways it can behave very much like one, apparently.

Congrats too on the work in string theory that led to the development of the amplitudihedron. Even Feynman would have approved; he really liked graphic approaches to tough QED problems, as you already know.

Fear not; 30 years of developing the math for string theory will not have been wasted, I'm certain. I'm actually relieved that the math is now in place to unify many different domains of physics, astrophysics and cosmology. Great job! We know, you don't hear it enough.

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