Happy Birthday, String Theory.
December 7, 2004 5:22 PM Subscribe
String Theory Turns 20 - first posited in 1984 as an explanation for the strong force, String Theory turns 20 this year. While some physicists celebrate, others are concerned that string theory isn't coming close to being a theory of everything as many had hoped. While it does reconcile quantum mechanics with Special Relativity, there is currently no mathematical proof for String Theory. Even more troubling, rather than providing one solid explanation for the universe, the many dimensions of string theory offer 10^100 different possible results.
Even more troubling, rather than providing one solid explanation for the universe, the many dimensions of string theory offer 10^100 different possible results.
Many consider this one of the singular stegnths of the theory. Also, having a legitimate use for the word "google" (10^100) how could you not use it?
posted by ChasFile at 5:57 PM on December 7, 2004
Many consider this one of the singular stegnths of the theory. Also, having a legitimate use for the word "google" (10^100) how could you not use it?
posted by ChasFile at 5:57 PM on December 7, 2004
Nitpick powers, activate!
While it does reconcile quantum mechanics with Special Relativity...
Actually, Quantum Field Theory did that. You may be thinking of general relativity — but the jury's still out on whether string theory really reproduces GR.
Having a legitimate use for the word "google" (10^100) how could you not use it?
"Google" is the search engine; "googol" is the number.
Sorry to inject such pedantry into the thread — we now return you to your regularly scheduled comments.
posted by Johnny Assay at 6:16 PM on December 7, 2004
While it does reconcile quantum mechanics with Special Relativity...
Actually, Quantum Field Theory did that. You may be thinking of general relativity — but the jury's still out on whether string theory really reproduces GR.
Having a legitimate use for the word "google" (10^100) how could you not use it?
"Google" is the search engine; "googol" is the number.
Sorry to inject such pedantry into the thread — we now return you to your regularly scheduled comments.
posted by Johnny Assay at 6:16 PM on December 7, 2004
Correction: quantum electrodynamics (QED) reconciles quantum mechanics and special relativity. Quite well actually. See here for a description of the g-2 prediction of QED which has been experimentally verified to 12 digits of precision. String theory's aim is to reconcile quantum mechanics and General Relativity, a theory of gravity that also predicts well at astronomical scales, but so far has predicted nothing that can be measured.
posted by fatllama at 6:18 PM on December 7, 2004
posted by fatllama at 6:18 PM on December 7, 2004
Darn. I was coming in to say what the posters above said.
Ah well. I'll add that string theory may only be 20 yrs old but its one of a line of theories which attempted to tackle the asymmetry problems in the universe by adding extra dimensions.
It goes back to Kaluza-Klein in 1919 really, though you could take it back to Minkowski. Later in his life, Einstein was exploring higher-dimensional frameworks as a path to the unification of gravity and electromagnetism.
The notion of symmetry is a key one in modern physics. One way to look at asymmetric processes in our universe (whether in time or space) is to try to imagine that we are only looking at a piece of a larger, symmetrical whole. Then the puzzle becomes how did we get from there to here - from perfect symmetry to this broken symmetry we live in.
posted by vacapinta at 6:59 PM on December 7, 2004
Ah well. I'll add that string theory may only be 20 yrs old but its one of a line of theories which attempted to tackle the asymmetry problems in the universe by adding extra dimensions.
It goes back to Kaluza-Klein in 1919 really, though you could take it back to Minkowski. Later in his life, Einstein was exploring higher-dimensional frameworks as a path to the unification of gravity and electromagnetism.
The notion of symmetry is a key one in modern physics. One way to look at asymmetric processes in our universe (whether in time or space) is to try to imagine that we are only looking at a piece of a larger, symmetrical whole. Then the puzzle becomes how did we get from there to here - from perfect symmetry to this broken symmetry we live in.
posted by vacapinta at 6:59 PM on December 7, 2004
Where there are strings there are branes.
More branes!
Mmm, branes.
posted by Wolfdog at 7:13 PM on December 7, 2004
More branes!
Mmm, branes.
posted by Wolfdog at 7:13 PM on December 7, 2004
...there is currently no mathematical proof for String Theory.
What are you thinking about here? Physical theories aren't proven mathematically -- theorems they are not. You prove String Theory by showing that it models observation correctly -- and currently we can't do that. As far as I know, String theory is mathematically difficult, but consistent. Does it rely on some unproven mathematical leap?
It is an important distinction. There is no "mathematical proof" for Newton's theory of gravitation, either. It is a mathematical consistent model that happens to (mostly) agree with experiment. That is all we would be hoping for with String Theory. But to know, we need to be able to observe things that are amazingly small.
posted by teece at 7:23 PM on December 7, 2004
What are you thinking about here? Physical theories aren't proven mathematically -- theorems they are not. You prove String Theory by showing that it models observation correctly -- and currently we can't do that. As far as I know, String theory is mathematically difficult, but consistent. Does it rely on some unproven mathematical leap?
It is an important distinction. There is no "mathematical proof" for Newton's theory of gravitation, either. It is a mathematical consistent model that happens to (mostly) agree with experiment. That is all we would be hoping for with String Theory. But to know, we need to be able to observe things that are amazingly small.
posted by teece at 7:23 PM on December 7, 2004
If you prefer your information presented with pictures and sounds to accompany the words, I'd recommend watching the Nova program based on Brian Greene's book. I spent three hours doing it a few weeks ago, and thought it was a pretty good introduction to string theory, even though it seems to be targeted for high schoolers. I don't remember Nova seeming so dumbed down, but if you get a kick out of bad re-enactments of physicists putting their ground-breaking research in the mailbox while you're doing your learning, you can't go wrong.
posted by gleckt at 7:28 PM on December 7, 2004
posted by gleckt at 7:28 PM on December 7, 2004
teece has it right. Theories are chock full of equations etc. but they're astonishingly lacking in actual observational proof (particularly in physics). String theory (as implausible at it may sound) is just as probable as any unified theory, even if it ultimately proves to be completely false.
Either way, it's an exciting sci-fi read and so unbelievably out there that it's absolutely incredible that it's considered "sound" science (by some).
I love it, even though I may not necessarily believe it. ;)
posted by purephase at 7:33 PM on December 7, 2004
Either way, it's an exciting sci-fi read and so unbelievably out there that it's absolutely incredible that it's considered "sound" science (by some).
I love it, even though I may not necessarily believe it. ;)
posted by purephase at 7:33 PM on December 7, 2004
fatllama: actally, QED is a quantum field theory. Go read chapter 2 of Peskin and Schroeder; there they describe why one needs a QFT to describe physics at small length scales, (where quantum mechanical effects are important) and large energies (where relativistic effects are important).
I'm not tryin' to rag on you, but it seems you're a physics grad student. I'm one, too. It's our job (as physicists) to bring clarity to public discussions of what the hell it is we're doing with the resources the public so generously provides.
(Wow, pedantic criticism of a post which is pedantically critical of of a post, self-described as pedantic! Who says physics is no fun?)
posted by funkbrain at 7:34 PM on December 7, 2004
I'm not tryin' to rag on you, but it seems you're a physics grad student. I'm one, too. It's our job (as physicists) to bring clarity to public discussions of what the hell it is we're doing with the resources the public so generously provides.
(Wow, pedantic criticism of a post which is pedantically critical of of a post, self-described as pedantic! Who says physics is no fun?)
posted by funkbrain at 7:34 PM on December 7, 2004
Seeing this thread with 11 comments and baby jesus + creation science currently at 89 is really bumming me out this fine Tuesday evening. So let's kick it up a notch.
Vacapinta is referring to the notion that while the phenomena known separately as the strong nuclear, weak nuclear, electromagnetic, and gravitational forces obey completely different physics today, most physicists believe that moments after the big bang these forces were governed by the same physics. For instance, the interaction strength of gravity and electromagnetism differ today by 40 orders of magnitude but in a short epoch following the big bang they were of equal strength. See for instance this cartoon from this page.
For those who want to keep score at home, here's how the next 10 years play out. These days, popular variants of string theory require supersymmetry which is a prediction that for every fermionic particle we've discovered so far there is a much heavier (thus harder to manufacture at colliders) bosonic particle which have exactly the right properties to make the grand unification of the forces we've been talking about possible near the big bang. Similarly there should be fermionic superpartners for all the bosons we know of now. Plus the Higgs boson, which is how we think particles get to be the mass that they are. It hasn't been found yet (conclusively), but the Higgs is the first order of business when the LHC turns on at CERN so stay tuned.
on preview - Funkbrain, my earlier post was correcting the poster, not Johnny Assay who is perfectly correct and posted while I was typing. I've been through more than Chapter 2 of Peskin. But you're right, it is more correct to say that QFT has married quantum mechanics with special relativity; though QED is by far the most calculable and tested field theory to date. To wit, precision calculation of magnetic moments of hadrons isn't even possible under Quantum Chromodynamics; go lattice, go!
posted by fatllama at 8:17 PM on December 7, 2004
Vacapinta is referring to the notion that while the phenomena known separately as the strong nuclear, weak nuclear, electromagnetic, and gravitational forces obey completely different physics today, most physicists believe that moments after the big bang these forces were governed by the same physics. For instance, the interaction strength of gravity and electromagnetism differ today by 40 orders of magnitude but in a short epoch following the big bang they were of equal strength. See for instance this cartoon from this page.
For those who want to keep score at home, here's how the next 10 years play out. These days, popular variants of string theory require supersymmetry which is a prediction that for every fermionic particle we've discovered so far there is a much heavier (thus harder to manufacture at colliders) bosonic particle which have exactly the right properties to make the grand unification of the forces we've been talking about possible near the big bang. Similarly there should be fermionic superpartners for all the bosons we know of now. Plus the Higgs boson, which is how we think particles get to be the mass that they are. It hasn't been found yet (conclusively), but the Higgs is the first order of business when the LHC turns on at CERN so stay tuned.
on preview - Funkbrain, my earlier post was correcting the poster, not Johnny Assay who is perfectly correct and posted while I was typing. I've been through more than Chapter 2 of Peskin. But you're right, it is more correct to say that QFT has married quantum mechanics with special relativity; though QED is by far the most calculable and tested field theory to date. To wit, precision calculation of magnetic moments of hadrons isn't even possible under Quantum Chromodynamics; go lattice, go!
posted by fatllama at 8:17 PM on December 7, 2004
fatllama: my bad.
also, thanks for bringing so much to this conversation. i'm not going to put the time in to contribute to the discussion; i've been reading MeFi instead of working on my thesis...
posted by funkbrain at 8:38 PM on December 7, 2004
also, thanks for bringing so much to this conversation. i'm not going to put the time in to contribute to the discussion; i've been reading MeFi instead of working on my thesis...
posted by funkbrain at 8:38 PM on December 7, 2004
funk - Please note one side benefit of babysitting a long runtime experiment. Except that's really no excuse - don't you guilt me into changing my homepage to something more productive! ;-) Best wishes on the thesis.
posted by fatllama at 8:47 PM on December 7, 2004
posted by fatllama at 8:47 PM on December 7, 2004
Someone, quick, blow my mind.
posted by orange clock at 9:26 PM on December 7, 2004
posted by orange clock at 9:26 PM on December 7, 2004
my branes hurt.
posted by five fresh fish at 9:28 PM on December 7, 2004
posted by five fresh fish at 9:28 PM on December 7, 2004
This is one of those threads that, while fascinating to me, leaves me with a sense of dread because I feel too stupid to follow it.
I've read one of Brian Greene's books, and I'd like to read another. I'm not sure I'll get it. [sigh]
posted by TeamBilly at 5:54 AM on December 8, 2004
I've read one of Brian Greene's books, and I'd like to read another. I'm not sure I'll get it. [sigh]
posted by TeamBilly at 5:54 AM on December 8, 2004
in my late night posting efforts, i seem to have confused special and general relativity. i do this a lot even during reasonable hours - my apologies.
also, the line i used about there being no mathematical proof for string theory was pulled almost directly out of the new york times article i linked. last i knew, physicists still used math and brain greene in his interview talks about the math of string theory. i'm perfectly willing to accept that i could be completely misreading these sources, so again, sorry if this is a mistake.
now back to reading the comments - i just wanted to offer a short note of apology if i presented information inaccurately - i'm no expert on physics, i just like it.
posted by grapefruitmoon at 8:12 AM on December 8, 2004
also, the line i used about there being no mathematical proof for string theory was pulled almost directly out of the new york times article i linked. last i knew, physicists still used math and brain greene in his interview talks about the math of string theory. i'm perfectly willing to accept that i could be completely misreading these sources, so again, sorry if this is a mistake.
now back to reading the comments - i just wanted to offer a short note of apology if i presented information inaccurately - i'm no expert on physics, i just like it.
posted by grapefruitmoon at 8:12 AM on December 8, 2004
wait! i had my relativities straight the first time! that'll learn me to only read half the comments before responding.
ah well.
thankyou, fatllama for your comments. very interesting stuff. i wish i understood it well enough to discuss it a bit better!
posted by grapefruitmoon at 8:21 AM on December 8, 2004
ah well.
thankyou, fatllama for your comments. very interesting stuff. i wish i understood it well enough to discuss it a bit better!
posted by grapefruitmoon at 8:21 AM on December 8, 2004
fatllama keeps giving and giving! Thank you for the (possible) view of just over the horizon
For those of us who're non scientists has it gleck right - Green's book The Elegant Universe is a fascinating and demanding consideration of string theory for non-scientists such as me...
posted by dmt at 2:57 PM on December 8, 2004
For those of us who're non scientists has it gleck right - Green's book The Elegant Universe is a fascinating and demanding consideration of string theory for non-scientists such as me...
posted by dmt at 2:57 PM on December 8, 2004
Wait.... where's the part about balling up the string so every day of your life touches every other day, and you can 'leap' from day to day within your own lifespan?
posted by John Kenneth Fisher at 3:17 PM on December 8, 2004
posted by John Kenneth Fisher at 3:17 PM on December 8, 2004
Damn, I know that I know that "balling up string" demonstration from some tv program or other. Where's it from, JKF?
posted by five fresh fish at 3:33 PM on December 8, 2004
posted by five fresh fish at 3:33 PM on December 8, 2004
(Quantum Leap? But I've only seen the pilot and a couple other episodes of that show...)
posted by five fresh fish at 3:34 PM on December 8, 2004
posted by five fresh fish at 3:34 PM on December 8, 2004
:-) Quantum Leap indeed.
posted by John Kenneth Fisher at 2:46 PM on December 9, 2004
posted by John Kenneth Fisher at 2:46 PM on December 9, 2004
Objective reality may owe its existence to a 'darwinian' process that advertises certain quantum states.
posted by homunculus at 4:00 PM on December 27, 2004
posted by homunculus at 4:00 PM on December 27, 2004
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posted by Hat Maui at 5:51 PM on December 7, 2004