The Standard Model is experimentally-based quantum field theory (unlike completely useless string field theory), yet is slightly confused due to the purely speculative electroweak symmetry-breaking Higgs field and string theory is based upon the ignorant lie that spin-2 bosons are required for quantum gravity (see post on Fierz and Pauli’s error of the spin-2 graviton, linked here). U(1) hypercharge gives leptons and quarks particles their measured masses as explained physically on the post linked here. SU(2) is not just responsible for the 3 massive weak Z and W gauge bosons; it also causes massless versions, the charged massless bosons being responsible for positively and negatively charged electric fields, respectively (they propagate in the vacuum because the magnetic self-inductance – normally infinity for massless particles – is completely cancelled out for exchange radiation travelling along two directions, to and from each real charge; this is simply because magnetic field vectors for each component are equal and opposite in direction!; this mechanism also guarantees an exact equilibrium in exchange, so that the SU(2) Yang-Mills field equation term for charge transfer becomes inoperative; you can’t transfer any net charge because of the equilibrium; this constraint on the SU(2) Yang-Mills equation then automatically cancels the equation down to the form of the regular “Maxwellian” Abelian U(1) field equation which doesn’t include charge transfer by gauge bosons!).
Not In Our Lifetimes
A report from one of last Saturday’s events at the World Science Festival has string theorists Brian Greene and Shamit Kachru admitting that they’d be surprised to see experimental evidence for string theory in their lifetimes:
John Hockenberry, the panel’s moderator, asked Greene if he thought experimental evidence would come during his lifetime.
“I’d be surprised,” said Greene.
“And in your lifetime?” Hockenberry asked Kachru.
“…I’d be surprised,” conceded the young physicist reluctantly.
In the comments of that post by Dr Woit, commentators mention spin-2 gravitons:
Even if you can’t get falsifiable predictions from string theory, you could still falsify some of the assumptions it is built upon. E.g. spin-2 gravitons seem to everyone to be logical and necessary and require some kind of stringy framework unlike the spin-1 vector bosons in the Standard Model, but suppose gravity doesn’t conform to the expectations of Pauli and Fierz, and isn’t spin-2. It’s looked logical to Ptolemy to model the sun and stars daily orbiting the Earth… things did not turn out to be that simple.
Like Ptolemy’s epicycles, string theory is an ad hoc mathematical explanation for a widely held prejudice which still hasn’t a shred of experimental evidence behind it. Maybe we need a new Kepler.
OK, maybe string theory has not predicted anything definite about the real world yet. But via the AdS/CFT correspondence it has made many precise predictions about some gauge theories at strong coupling, like the N=4 supersymmetric Yang-Mills.
These predictions are testable. In fact, some of them have been tested by solving for some qauge theory quantities as functions of the coupling and comparing with string theory at strong coupling. It works!
Maybe this is not enough to satisfy some of you critics, but I find this amazing.
AdSCFTfan: Woit has been fairly consistent in saying that it’s string unification he thinks hasn’t panned out, not all the mathematical developments associated with string theory.
The interesting thing about the AdS/CFT correspondence conjecture is that it has nothing really going for it, yet is being falsely claimed on that blog comment reproduced above that the AdS/CFT is a correspondence (wrong, it’s a conjectured correspondence) that has been applied to “strong coupling, like the N=4 supersymmetric Yang-Mills [there is no evidence for strong couplings obeying supersymmetry unification predictions; on the contrary, as Woit points out in his book Not Even Wrong, the existing evidence for the trend of strong couplings observed in experiments rules out supersymmetry predictions, if the error bars are correctly estimated for the data!] These predictions are testable. In fact, some of them have been tested by solving for some qauge theory quantities as functions of the coupling and comparing with string theory at strong coupling. It works!
As mentioned before, Woit shows that the supersymmetric predictions of string theory so far are wrong according to the estimated error bars on data for strong couplings at the highest observed energies to date.] It is true that AdS/CFT is an approximate way to model strong interactions over a limited range of energies, because AdS (anti-de Sitter space) has a negative cosmological constant. This is a good way to mathematically approximate the strong nuclear force at energies where it causes universal attraction with the force increasing with increasing distance (rather than with the force falling with distance as occurs for gravity).
The strong force is attractive as is gravity, but the strong force differs from gravity not only in being vastly more powerful, but also in the fact that it’s coupling or effective charge strength, gets bigger with increasing distance (like the force increasing as you stretch an elastic band, the model used in the old “hadronic string theory” of the 1960s which predated the 10/11 dimensional superstring/supergravity theory that culminated with Witten’s work in 1995). The reason for the difference is physically due to the fact that there are 8 strong force gauge bosons (gluons) which are charged and cause an “antiscreening” effect, the opposite of the screening of electromagnetic charge between IR and UV cutoff energies by vacuum virtual fermion polarization caused by electric fields in QED.
The massive negative signed AdS cosmological constant in AdS/CFT has nothing to do with spacetime, because it is very unlike the small positive signed number currently accepted by the mainstream in order to model observed radial cosmological accelerations of supernovae away from us.
As we stated in earlier posts, even the currently accepted small cosmological constant (Lambda) in the Lambda-CDM model of cosmology was not predicted or by any relativistic or string theory, and the resulting Lambda-CDM model is just a convoluted, epicycle-type model invented in 1998 by ad hoc downward revision of the value of Einstein’s steady-state universe error of 1915, which (unlike AdS) had a massive positive cosmological constant which sought to cancel out gravitational attractions between galaxies and thus keep the observed universe stable and neither collapsing nor expanding, indefinitely (this stability was later disproved; it is an inherently unstable mathematical solution and such a universe would have no more enduring stability than a pen placed upright on its nib). Contrary to ignorant, ad hoc, adjustable parameter general relativity cosmological metrics and string theory theory ideas about a vacuum energy, spin-1 quantum gravity in 1996 predicted the acceleration and thus the “effective” cosmological constant precisely, by showing that the universe must have acceleration of ~Hc in order for gravity to operate by spin-1 gravitons, i.e. there is no mysterious “dark energy” as distinct from the gravitational field: the gravitational field is “dark energy” and therefore there is no separate cosmological constant, although we can predict the “effective value” from the spin-1 gravity mechanism.
Update: as an antidote to depression about string theory lies being used by ignorant media morons to censor the facts of physics until after you are long dead and buried, I strongly recommend Saturday night foam parties at Ibiza’s Eden nightclub
Above: Sat 12 June 2010 Ibiza Eden nightclub (two minutes walk from my hotel) foam party photographed at 5:56am local time Sunday 13th (San Antonio, Ibiza). They gave out free wristband passes for entry at 2am in the town centre, so I didn’t pay a penny. Eden nightclub has only just had its seasonal opening party, and is Keep your phone and money in a plastic bag in your pocket and wear swimming-type earplugs to reduce eardrum stresses when the volume goes up too high for comfort (you still hear the music fine). Don’t drink any alcohol or water if you just want to practice dancing all night long to keep fit and sensibly chat to girls in the chilling out room (being drunk doesn’t make you look attractive, while drinking water or soft drinks makes you look soft). Keep fully hydrated during the day before, then drink a full litre of mineral water immediately before you go to the club at 3am (for just over 3 hours of dancing, you will remain fine without another drink). The foam party began in a special slightly rough-finished circular area (located down from the main dance stage, which is smooth and would be too slippery for foam) around 5:50am and lasted about 20 minutes. It was a water party first (sprays from ceiling sprinklers), and then lots of foam pipes from the ceiling sprayed snow-like waist-deep soap foam.
Update (15 June 2010):
Dr Woit of Columbia University has a new Not Even Wrong blog post up:
Video of David Gross’s talk at the Physics at the LHC 2010 conference is now available. He devotes much of the talk to reviewing predictions he made back in 1993 of what would happen by 2008, and making new predictions for what will happen by 2020.
… His experimental predictions include a repeat of the 1993 ones (superpartners, new Z-mesons, and the Higgs, although now he only mentions one Higgs), except that he has now given up on even “cloudy” evidence of superstrings showing up at the TeV scale. …