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Author Topic:   String! Theory! What is it good for ?!?
onifre
Member (Idle past 2950 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 16 of 107 (535151)
11-13-2009 7:00 AM
Reply to: Message 8 by Iblis
11-12-2009 10:09 PM


Re: nuh UNH!
I thought string theory predicted that particles or waveforms or whatever they are like quarks, which we like to think of as dimensionaless points, are actually one-dimensional lines;
Yea, like I said, roughly speaking there are things inside quarks.
That 'thing' is a vibrating one dimensional string. The way you would find out would be with a large enough collider.
- Oni

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onifre
Member (Idle past 2950 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


(2)
Message 17 of 107 (535168)
11-13-2009 10:49 AM
Reply to: Message 12 by AnswersInGenitals
11-13-2009 1:55 AM


Re: Popper pooped.
The engineering that went into the designing and building of the LHC was primarily based on Newtonian mechanics, classical thermodynamics, and Maxwell's equations, all falsified theories. The engineers did not have to differ to relativistic quantum field theory or general relativity, two theories that have yet to be falsified, in the design process.
Are you saying that the LHC doesn't incorporate SR...?
If you are, this is incorrect. Relativistic mass is a fundamental aspect of the LHC due to the high momentum the particles are taken to.
- Oni

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slevesque
Member (Idle past 4640 days)
Posts: 1456
Joined: 05-14-2009


Message 18 of 107 (535190)
11-13-2009 3:12 PM
Reply to: Message 15 by Iblis
11-13-2009 3:39 AM


Re: NM, I'm a Big Dope
That is not exactly what I had in mind. I read that in an article, so it may be hard for me to find it on the internet.

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slevesque
Member (Idle past 4640 days)
Posts: 1456
Joined: 05-14-2009


(1)
Message 19 of 107 (535192)
11-13-2009 3:21 PM
Reply to: Message 11 by Huntard
11-13-2009 1:48 AM


Re: Yes, that's science
Supposing my anecdote is true, then I think the problem is much deeper. Because string theory has been viewed as unfalsifiable for this very reason: it can adapt to anything. Even when it predicts something in a specific direction, and observation shows the opposite, and can still be reworked and twisted, and a little more branes here, and a little exra-dimension there, and pop there it goes string theory is not shown to be wrong. (this is carricatural of course)
This is what annoyes many physicists in the community, and I remember reading a quote along the lines of:
'' I don't like that they (speaking of string theorists) can just rework the theory at will. I don't like that they can explain everything and anything, and that they will never be wrong, I don't like ...''
I couldn't say that this is anywhere near exact to the quote, but the general idea that stemed from it was this.
Because if a theory can adapt to any situation (even two situation that are distinctly opposite), to any data, than I do not think we can legitimately call it science anymore.

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slevesque
Member (Idle past 4640 days)
Posts: 1456
Joined: 05-14-2009


Message 20 of 107 (535193)
11-13-2009 3:28 PM
Reply to: Message 12 by AnswersInGenitals
11-13-2009 1:55 AM


Re: Popper pooped.
I find a serious lack of Culture in this post. And also a clear condescension of philosophy.
Just read the many quotes fro mthe greatest scientists to have lived, and you can see that they had a great understanding of philosophy. Just look at all those einstein quotes that everyone have in their signatures.
Karl Popper has made maybe the single most important contribution to science as a whole in the 20th century, which came in the form of his book ''The logic of scientific discovery''.

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Iblis
Member (Idle past 3895 days)
Posts: 663
Joined: 11-17-2005


Message 21 of 107 (535209)
11-13-2009 6:26 PM
Reply to: Message 19 by slevesque
11-13-2009 3:21 PM


Re: Yes, that's science
Yeah, I still can't find it. Don't get me wrong, supersymmetry, symmetry breaking, and field theory are all components of superstring just like general relativity and Lorentz invariance are; so it's very likely that one of the people in such an argument would be a string theorist.
I would love to find some actual quotes though.

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slevesque
Member (Idle past 4640 days)
Posts: 1456
Joined: 05-14-2009


Message 22 of 107 (535251)
11-14-2009 2:01 AM
Reply to: Message 21 by Iblis
11-13-2009 6:26 PM


Re: Yes, that's science
Ok, so if I remember correctly, it was in an article that I read back at my parents house. I'm going there next weekend, so I'll bring it back with me so as to get the actual quotes.

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Iblis
Member (Idle past 3895 days)
Posts: 663
Joined: 11-17-2005


Message 23 of 107 (535259)
11-14-2009 5:34 AM
Reply to: Message 22 by slevesque
11-14-2009 2:01 AM


Re: Yes, that's science
Ok, I'm getting closer to it. First off, here's this from the San Francisco chronicle
String theorists and their foes can't even agree on what constitutes success or failure. For example, the most unexpected and counterintuitive discovery of recent science occurred in the 1990s, when astrophysicists at Berkeley and elsewhere realized the universe is expanding faster with time. The apparent reason: a mysterious dark energy pervades space and drives the accelerated expansion.
Critics mock superstringers because their so-called theory of everything failed to predict this colossal discovery. String theorists fire back that no one else predicted it, either
'Theory of everything' tying researchers up in knots
Sound familar? Honestly, though, this sort of development strikes me as good evidence that superstring is not a pseudo-science, particularly in the hoax sense. Why? Because if it were, with the content it has, someone would have been able to throw together a provisional coup of an interpretation almost immediately.
Don't believe me? Fine, I will do it. Dark energy is energy that leaks in from other branes, just as "dark matter" is actually gravity that leaks in from other branes. The objection that we don't have any missing energy to correspond to the energy that would be leaking out of our brane is just as simple; energy, like photons, is bound to stable branes, unlike gravitons, which are looped and have no "loose ends" to lock them inside.
How is the energy getting out of those other branes into ours, then? Simple. There are a huge number of different universes in M-theory, some of which are similar to ours and some of which are wildly different. As the "fine-tuning" argument has demonstrated, a lot of those universes with even mildly different dimensionless constants, wouldn't last 3 minutes! Once they collapse, their constituent energy is no longer bound, and migrates whichever direction entropy happens to take it. Eventually it tends to settle in more long-term universes like our own.
"Oh dear," says God, "I hadn't thought of that," and promptly vanished in a puff of logic.
"Oh, that was easy," says Man, and for an encore goes on to prove that black is white and gets himself killed on the next zebra crossing.
--Douglas Addams
Edited by Iblis, : brane phart

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Iblis
Member (Idle past 3895 days)
Posts: 663
Joined: 11-17-2005


Message 24 of 107 (535263)
11-14-2009 6:49 AM
Reply to: Message 22 by slevesque
11-14-2009 2:01 AM


Re: Yes, that's science
Now on to the goodies. First up is Richard Feynmann, Nobel Laureate in Physics and coiner of the "cargo cult science" pejorative
Shortly before his death, Feynman criticized string theory in an interview: "I don't like that they're not calculating anything," he said. "I don't like that they don't check their ideas. I don't like that for anything that disagrees with an experiment, they cook up an explanationa fix-up to say, 'Well, it still might be true.'"
Richard Feynman - Wikipedia
He died in 1988, so he isn't talking specifically about dark energy, but he gets quoted a lot in this argument so he well may be what you remember reading.
There are plenty of other candidates, though. Here's a snap of Robert Laughlin, another Nobel in Physics, from the Guardian
An unprovable theory that talks of unseeable parallel universes and 10-dimensional space has proved too much for some physicists. 'Quasi-theology' and 'post-modern' have been among the most polite terms used; 'bogus' and 'nonsense' among the less forgiving.
'Far from a wonderful technological hope for a greater tomorrow, string theory is the tragic consequence of an obsolete belief system,' said Stanford University's Robert Laughlin, winner of the 1998 Nobel prize for physics.
For a theory that purports to explain the entire structure of the universe, such a high-level attack is very serious.
String theory: Is it science's ultimate dead end? | Science | The Guardian
He won his in 1998 and is still alive and publishing.
Edited by Iblis, : coynte

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cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(1)
Message 25 of 107 (535298)
11-14-2009 1:31 PM
Reply to: Message 20 by slevesque
11-13-2009 3:28 PM


Re: Popper pooped.
Karl Popper has made maybe the single most important contribution to science as a whole in the 20th century, which came in the form of his book ''The logic of scientific discovery''.
I think you'll find that Popper is not such a hero in the world of theoretical physics. And he never could quite handle the essence of quantum mechanics and the methodology behind the development of QCD and similar theories...
ABE: but this is for yet another thread
Edited by cavediver, : No reason given.

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cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(1)
Message 26 of 107 (535299)
11-14-2009 1:42 PM
Reply to: Message 24 by Iblis
11-14-2009 6:49 AM


Re: Yes, that's science
Here's a snap of Robert Laughlin, another Nobel in Physics
Who gives a crap about what Laughlin thinks? His field is condensed matter physics. He's so lost that he thinks that he's qualified to theorise about black holes (and why they don't exist :rolleyes without understanding even the basics. He's a laughing stock to relativists.
Richard Feynmann
Now Dick is another matter. But he has always been about calculations. His development of QED was simply to get out the numbers he wanted. No disgrace, and he is still God to many of us - he and I share birthdays But his approach to quantum gravity is a different approach... (not least, that it is now from the other side!)
Edited by cavediver, : No reason given.

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cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(2)
Message 27 of 107 (535306)
11-14-2009 4:36 PM
Reply to: Message 19 by slevesque
11-13-2009 3:21 PM


Re: Yes, that's science
Because string theory has been viewed as unfalsifiable for this very reason: it can adapt to anything.
What is reality? - There are several of us who believe that our reality is just one infinitesimal part of a Grand Ensemble - an ensemble that makes the multiverse just our local backyard. This by necessity will involve a theory with an ability to produce an infinitude of possible realities. The fact that M-theory seems to be doing this is exactly what we expected. *If* this is how reality is built, then I guess you're suggesting that we should abandon research in the correct direction, and go play with some wrong theories that you will find more philosophically satisfying. No thanks. I don't give a shit about the philosophy. As a scientist, I'm trying to understand the nature of reality. If M-theory has something to do with it, great. If it doesn't, great.

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Replies to this message:
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cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(2)
Message 28 of 107 (535311)
11-14-2009 5:17 PM
Reply to: Message 10 by slevesque
11-13-2009 1:29 AM


Didn't string theory predict that the cosmological constant would be negative or null
Let me save you all the trouble and explain - you are essentially correct, but it is not the way we would look at it. We couldn't get a positive Cosmological Constant out of String Theory. You could say this is a prediction but we saw it as a major drawback - we couldn't generate cosmologically interesting solutions related to de-Sitter space, and then when we discovered that we were living in a de-Sitter-like space, there was concern. However, this provided the necessary motivation and inspiration to look for an answer. An answer was found, that opened the doors to the (infamous) String Landscape. This was in many ways what I had been waiting for and I was very excited. For all my time in Quantum Gravity I never expected to find a single obvious reduction of any grand theory into the Standard Model, a compactification that would give exactly what we see. The Standard Model is a mess, and whatever reduction gives rise to it will also be a mess, and essentially unpredictable.

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Straggler
Member
Posts: 10333
From: London England
Joined: 09-30-2006


(2)
Message 29 of 107 (535326)
11-14-2009 7:37 PM
Reply to: Message 28 by cavediver
11-14-2009 5:17 PM


Questions
My (admittedly limited) understanding is that M theory provides a sort of working ability to pertubitively (i.e. calculate in practical terms) various aspects of the standard model whilst also incorporating gravity. And that it is essentially this that means it is taken seriously. Because no other model even gets that far.
Is this correct?
Even though the underlying theory behind the working calculations is not known at a deep (i.e. truly quantum gravity) level this is the reason that theorists take the string theory model as seriously as they do. It can derive the standard model and gravity without breaking out into a mass of infinities. So to speak, and if one already knows what one is looking for.
Is that fair?
I have a couple of questions if you are willing to answer them:
1) What is supersymmetry (i.e. that which make string theory into superstring theory)?
2) What are solitonic solutions and why are they important?
If all of this is too much then even being pointed at some references that might be appropriately levelled would be appreciated.

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Iblis
Member (Idle past 3895 days)
Posts: 663
Joined: 11-17-2005


Message 30 of 107 (535327)
11-14-2009 7:38 PM
Reply to: Message 26 by cavediver
11-14-2009 1:42 PM


Re: Yes, that's science
Who gives a crap about what Laughlin thinks? His field is condensed matter physics. He's so lost that he thinks that he's qualified to theorise about black holes
Maybe I don't have a good idea of what "condensed matter physics" is. Maybe that sounds to me like exactly the sort of thing that would make one an expert on black holes. (They are made out of condensed matter, ain't they?) Maybe a bit more information about the distinction is in order?
(and why they don't exist :rolleyes
Yeah he's a real hoot!
George and I made a very plausible case that general relativity, as we have observed it experimentally, could be perfectly true, and yet fail to describe a black hole event horizon properly, said Laughlin. What would allow this to happen is failure of the relativity principle on very short-length scales.
His and Chapline’s model, he argues, fixes violations of quantum mechanicssuch as information loss and the freezing of time at a black hole’s event horizon in traditional black hole models. Laughlin notes that the argument may offend his peers, but that they have no valid criticism of his and his partner’s arguments. He insists their redefinition is correct.
The point is that there is no way to tell one way or the other right now, he said. If there were, there would be no controversy.
http://seedmagazine.com/...e/what_if_black_holes_didnt_exist
So, should we just "teach the controversy"?
Anyway, he's fun to read regardless
But skeptics suggest it's the latest sign of how string theorists, sometimes called "superstringers," try to colorfully camouflage the theory's flaws, like "a 50-year-old woman wearing way too much lipstick," jokes Robert B. Laughlin, a Nobel Prize-winning physicist at Stanford. "People have been changing string theory in wild ways because it has never worked."
Already, the split over string theory has caused tensions at some of the nation's university physics departments. "The physics department at Stanford effectively fissioned over this issue," said Laughlin, now on sabbatical in South Korea. "I think string theory is textbook 'post-modernism' fueled by irresponsible expenditures of money."
'Theory of everything' tying researchers up in knots
Here's some more
"If Einstein were alive today, he would be horrified at this state of affairs. He would upbraid the profession for allowing this mess to develop and fly into a blind rage over the transformation of his beautiful creations into ideologies and the resulting proliferation of logical inconsistencies. Einstein was an artist and a scholar but above all he was a revolutionary. His approach to physics might be summarized as hypothesizing minimally. Never arguing with experiment, demanding total logical consistency, and mistrusting unsubstantiated beliefs. The unsubstantial belief of his day was ether, or more precisely the nave version of ether that preceded relativity. The unsubstantiated belief of our day is relativity itself. It would be perfectly in character for him to reexamine the facts, toss them over in his mind, and conclude that his beloved principle of relativity was not fundamental at all but emergent-a collective property of the matter constituting space-time that becomes increasingly exact at long length scales but fails at short ones. This is a different idea from his original one but something fully compatible with it logically, and even more exciting and potentially important. It would mean that the fabric of space-time was not simply the stage on which life played out but an organizational phenomenon, and that there might be something beyond."
http://physicsmathforums.com/showthread.php?t=2722
Making speeches isn't really the same kind of thing as doing experiments and observing results and modifying your hypothesis to agree with the results and doing more experiments and so on though, is it?
Now Dick is another matter
Did you know him personally?

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