String theory is what?

[The Dagda]

Nobody is reading the replies of the others in some instances here. I'm not surprised, going by the length of some of them, but someone - have a look, guys - just quoted what I said thinking it was one of the protagonists in this verbal kerfuffle. Now I know that a mistake is easy to make, but the fact that I'm the only one who picked it up implies that I'm the only one who's actually reading the whole things. I'm sure if everyone had been paying attention it would have been rather vigorously pointed out. Please don't now, as I did it already. Maybe you all actually agree but you don't realise.

I don't think you understand what is being said any better than nautilidae understands tensor mathematics. Or gravitation in a non Euclidean framework.

[The Dagda]

String theory is what?

Trigger Warning!!!1! :

Boring

No one's making you read it. Turn off your TV and go and do something less boring instead is my advice.

I lold.

Nobody is reading the replies of the others in some instances here. I'm not surprised, going by the length of some of them, but someone - have a look, guys - just quoted what I said thinking it was one of the protagonists in this verbal kerfuffle. Now I know that a mistake is easy to make, but the fact that I'm the only one who picked it up implies that I'm the only one who's actually reading the whole things. I'm sure if everyone had been paying attention it would have been rather vigorously pointed out. Please don't now, as I did it already. Maybe you all actually agree but you don't realise.

I think that's about as likely as the Church of the Latter Day Saints throwing their lot in with the Sikhs...



They do get cranky with each other, don't they?

Not at all it's just a posting style. If I was angry I'd not be posting at all.

[lpetrich]

I think that I'll review where we are about the Standard Model and possible GUT's, and see how string theory fits in.

The details are a bit arcane and lengthy, so I'm putting them in spoiler tags.

The short-short version -- one can get the Standard Model's multiplet structure out of string theory by a series of symmetry breakings.

Trigger Warning!!!1! :

I'll post in somewhat abbreviated fashion, but if anyone wants me to expand on it, I will.

At low energies (< a few hundred GeV), the gauge symmetry is SU(3) (QCD) * U(1) (electromagnetism)
I'll list the particles by (QCD multiplet, electric charge):

Higgs: at least one of (1,0), possible (1,+/-1)
Elementary Fermions: U (3,2/3), D (3,-1/3), N (1,0), E (1,-1)
Their antiparticles: U* (3*,-2/3), D* (3*,1/3), N* (1,0), E* (1,1)
Gauge: gluon (8,0), W (1,+/-1), Z (1,0), photon (1,0)

The unbroken Standard Model with two Higgs doublets, necessary for supersymmetric extensions of it:

The gauge symmetry is SU(3) (QCD) * SU(2) (weak isospin) * U(1) (weak hypercharge)

Left-handed Higgs: Hu (1,2,1/2), Hd (1,2,-1/2)
Right-handed Higgs: Hu* (1,2,-1/2), Hd* (1,2,1/2)
Left-handed EF's: Q (3,2,1/6), U* (3*,1,-2/3), D* (3*,1,1/3), L (3,2,-1/2), N* (1,1,0), E* (1,1,1)
Right-handed EF's: Q* (3*,2,1/6) U (3,1,2/3), D (3,1,-1/3), L* (3*,2,1/2), N (1,1,0), E (1,1,-1)
Gauge: gluon (8,1,0), W (1,3,0) (weak isospin), B (1,1,0) (weak hypercharge)

With supersymmetry, the Higgses and the EF"s form "Wess-Zumino" multiplets, with spins 0 and 1/2. The gauge particles have spins 1 and 1/2.

-

The simplest GUT with a single gauge multiplet is the SU(5) Georgi-Glashow model. Its particle content is

Higgs:
Left: Hu(5) = Hu + Hql (3,1,-1/3)
Left: Hd(5*) = Hd + Hqr* (3*,1,1/3)
Right: Hu(5*) = Hu* + Hql* (3*,1,1/3)
Right: Hd(5*) = Hd* + Hqr (3,1,-1/3)
EF's:
Left: F(1) = N*
Right: F(5) = D + L*
Left: F(10) = Q + U* + E*
Right: F(10*) = Q* + U + E
Left: F(5*) = D* + L
Right: F(1*) = N
Gauge:
G(24) = gluon + W + B + XY (3*,1,5/6 ) + XY* (3,1,-5/6)

The Georgi-Glashow model predicts some extra particles, which can cause proton and bound-neutron decay.
I'll give their low-energy multiplet values here:

A down-like "Higgs quark" (Hql, Hqr, Hql*, Hqr*): Hq (3,-1/3)
XY gauge particle: X (3*,4/3), Y (3*,1/3)

It has not only gauge unification, but also mass unification for down-like quarks and charged leptons. It has two Higgs multiplet pairs and three EF multiplet pairs per generation, not exactly one.


One can go further with a SO(10) symmetry. It will break into SU(5) * U(1) where the latter is related to B-L, (baryon number) - (lepton number).
I'll give the "B-L hypercharge" alongside the SU(5) multiplet number:

Higgs:
Left: H(10) = Hu(5,-2) + Hd(5*,2)
Right: H(10)* = Hu(5*,2) + Hd(5,-2)
EF's:
Left: F(16) = F(1,5) + F(10,1) + F(5*,-3)
Right: F(16*) = F(1*,-5) + F(10*,-1) + F(5,3)
Gauge:
G(45) = G(24,0) + G(10,-4) + G(10*,4) + G(1,0)

The SO(10) model has some additional particles, which are all gauge particles.

The Higgses are in one multiplet pair, and the EF's are in one multiplet pair per generation. This not only makes mass unification for all the EF's, it prevents cross-generation decay.

So we've reduced the Standard Model to 9 multiplets. Can we go further?

We can, with a bigger symmetry called E6, which breaks down into SO(10) * U(1)

Higgs + EF's:
Left: F(27) = F(16,1) + F(10,-2) + F(1,4)
Right: F(27*) = F(16*,-1) + F(10,2) + F(1,-4)
Gauge:
G(78) = G(27,0) + G(16,-3) + G(16*,3) + G(1,0)

One of the F(10,-2), F(-10,2) pairs becomes the SO(10) Higgses -- the other two must get GUT-scale masses. This may explain part of the mass pattern of elementary fermions -- the Higgses may live in the generation with the tau lepton, bottom quark, and top quark, with some "cross talk" due to symmetry breaking.

This has gotten down to 7 multiplets. Can we proceed further?

String theory to the rescue.

All the five kinds of superstrings have a supergravity multiplet in their low-energy limits, and some of them also have a gauge-field multiplet in those limits. The possible gauge symmetries are constrained by quantum-mechanical consistency to SO(10) and E8*E8; their superstrings are types HO and HE.

Superstrings prefer to live in 10 space-time dimensions, so it's expected that 6 of them will compactify, becoming a GUT-to-Planck-sized ball. This is also a kind of symmetry breaking, it must be said.

This compactification will interact with the gauge field, breaking one of the E8's to E6 * SU(3):

Gauge:
G(248) = G(78,1) + G(1,8) + G(27,3) + G(27*,3*)

Thus, *all* the Standard-Model particles emerge from *one* gauge multiplet, three generations and all. The spin-0 ones get their spin reduced from 1 as a side effect of compactification.

That ball will also induce further symmetry breaking, the details of which are dependent on its topology. It can have numerous possible topologies, thus producing numerous possible symmetry-breaking patterns.

Even if one of them could be shown to produce the entire Standard Model, one then feels compelled to ask: why that one and not another one? There does not seem much of a hint in string theory as to which one might be "preferred".

[Trolldor]

...what?

[hackenslash]

String theory is what?

Trigger Warning!!!1! :

Boring

No, that would be Quantum Theory.

[The Dagda]

I think that I'll review where we are about the Standard Model and possible GUT's, and see how string theory fits in.

The details are a bit arcane and lengthy, so I'm putting them in spoiler tags.

The short-short version -- one can get the Standard Model's multiplet structure out of string theory by a series of symmetry breakings.

Trigger Warning!!!1! :

I'll post in somewhat abbreviated fashion, but if anyone wants me to expand on it, I will.

At low energies (< a few hundred GeV), the gauge symmetry is SU(3) (QCD) * U(1) (electromagnetism)
I'll list the particles by (QCD multiplet, electric charge):

Higgs: at least one of (1,0), possible (1,+/-1)
Elementary Fermions: U (3,2/3), D (3,-1/3), N (1,0), E (1,-1)
Their antiparticles: U* (3*,-2/3), D* (3*,1/3), N* (1,0), E* (1,1)
Gauge: gluon (8,0), W (1,+/-1), Z (1,0), photon (1,0)

The unbroken Standard Model with two Higgs doublets, necessary for supersymmetric extensions of it:

The gauge symmetry is SU(3) (QCD) * SU(2) (weak isospin) * U(1) (weak hypercharge)

Left-handed Higgs: Hu (1,2,1/2), Hd (1,2,-1/2)
Right-handed Higgs: Hu* (1,2,-1/2), Hd* (1,2,1/2)
Left-handed EF's: Q (3,2,1/6), U* (3*,1,-2/3), D* (3*,1,1/3), L (3,2,-1/2), N* (1,1,0), E* (1,1,1)
Right-handed EF's: Q* (3*,2,1/6) U (3,1,2/3), D (3,1,-1/3), L* (3*,2,1/2), N (1,1,0), E (1,1,-1)
Gauge: gluon (8,1,0), W (1,3,0) (weak isospin), B (1,1,0) (weak hypercharge)

With supersymmetry, the Higgses and the EF"s form "Wess-Zumino" multiplets, with spins 0 and 1/2. The gauge particles have spins 1 and 1/2.

-

The simplest GUT with a single gauge multiplet is the SU(5) Georgi-Glashow model. Its particle content is

Higgs:
Left: Hu(5) = Hu + Hql (3,1,-1/3)
Left: Hd(5*) = Hd + Hqr* (3*,1,1/3)
Right: Hu(5*) = Hu* + Hql* (3*,1,1/3)
Right: Hd(5*) = Hd* + Hqr (3,1,-1/3)
EF's:
Left: F(1) = N*
Right: F(5) = D + L*
Left: F(10) = Q + U* + E*
Right: F(10*) = Q* + U + E
Left: F(5*) = D* + L
Right: F(1*) = N
Gauge:
G(24) = gluon + W + B + XY (3*,1,5/6 ) + XY* (3,1,-5/6)

The Georgi-Glashow model predicts some extra particles, which can cause proton and bound-neutron decay.
I'll give their low-energy multiplet values here:

A down-like "Higgs quark" (Hql, Hqr, Hql*, Hqr*): Hq (3,-1/3)
XY gauge particle: X (3*,4/3), Y (3*,1/3)

It has not only gauge unification, but also mass unification for down-like quarks and charged leptons. It has two Higgs multiplet pairs and three EF multiplet pairs per generation, not exactly one.


One can go further with a SO(10) symmetry. It will break into SU(5) * U(1) where the latter is related to B-L, (baryon number) - (lepton number).
I'll give the "B-L hypercharge" alongside the SU(5) multiplet number:

Higgs:
Left: H(10) = Hu(5,-2) + Hd(5*,2)
Right: H(10)* = Hu(5*,2) + Hd(5,-2)
EF's:
Left: F(16) = F(1,5) + F(10,1) + F(5*,-3)
Right: F(16*) = F(1*,-5) + F(10*,-1) + F(5,3)
Gauge:
G(45) = G(24,0) + G(10,-4) + G(10*,4) + G(1,0)

The SO(10) model has some additional particles, which are all gauge particles.

The Higgses are in one multiplet pair, and the EF's are in one multiplet pair per generation. This not only makes mass unification for all the EF's, it prevents cross-generation decay.

So we've reduced the Standard Model to 9 multiplets. Can we go further?

We can, with a bigger symmetry called E6, which breaks down into SO(10) * U(1)

Higgs + EF's:
Left: F(27) = F(16,1) + F(10,-2) + F(1,4)
Right: F(27*) = F(16*,-1) + F(10,2) + F(1,-4)
Gauge:
G(78) = G(27,0) + G(16,-3) + G(16*,3) + G(1,0)

One of the F(10,-2), F(-10,2) pairs becomes the SO(10) Higgses -- the other two must get GUT-scale masses. This may explain part of the mass pattern of elementary fermions -- the Higgses may live in the generation with the tau lepton, bottom quark, and top quark, with some "cross talk" due to symmetry breaking.

This has gotten down to 7 multiplets. Can we proceed further?

String theory to the rescue.

All the five kinds of superstrings have a supergravity multiplet in their low-energy limits, and some of them also have a gauge-field multiplet in those limits. The possible gauge symmetries are constrained by quantum-mechanical consistency to SO(10) and E8*E8; their superstrings are types HO and HE.

Superstrings prefer to live in 10 space-time dimensions, so it's expected that 6 of them will compactify, becoming a GUT-to-Planck-sized ball. This is also a kind of symmetry breaking, it must be said.

This compactification will interact with the gauge field, breaking one of the E8's to E6 * SU(3):

Gauge:
G(248) = G(78,1) + G(1,8) + G(27,3) + G(27*,3*)

Thus, *all* the Standard-Model particles emerge from *one* gauge multiplet, three generations and all. The spin-0 ones get their spin reduced from 1 as a side effect of compactification.

That ball will also induce further symmetry breaking, the details of which are dependent on its topology. It can have numerous possible topologies, thus producing numerous possible symmetry-breaking patterns.

Even if one of them could be shown to produce the entire Standard Model, one then feels compelled to ask: why that one and not another one? There does not seem much of a hint in string theory as to which one might be "preferred".

Interesting total mathematical waffle and impenetrable but interesting.

I still think that's a maths mode and E6 is dangerously complicated to the point of having infinite solutions, which makes it again a theory of anything. Too complicated too background independant, or dependant and not experimental, to inferred from other models. Too indiscrete. Too bad.

[lpetrich]

Interesting total mathematical waffle and impenetrable but interesting.

It won't be impenetrable to someone familiar with "Lie groups" and "Lie algebras" and their representations. A Lie group is an abstract-algebra group with members specified by continuous parameters. A Lie group can be generated from a Lie algebra:

R(x) = exp(L.x)

Lie-group member R(x), Lie algebra L, parameters x.

For example, the 2D rotations form a Lie group:

(cos(a), -sin(a); sin(a), cos(a)) for parameter a

Its Lie algebra has one member: (0, -1; 1, 0).

3D rotations have a 3-member Lie algebra, each member being for rotation around each coordinate direction, and n-D ones a Lie algebra with dimension (1/2)*n*(n-1). It's SO(n) -- the special orthogonal matrices with dimension n. The "special" part is their determinants all being 1.

Generalizing to complex numbers gives the unitary-matrix group U(n), which splits into SU(n) * U(1). The group U(1) is of all complex numbers with absolute value 1: exp(i*a), while SU(n) matrices have determinant 1.

The SU(2) Lie algebra has Pauli matrices as its members; its group members are exp(i*s.x) for Pauli matrices s and 3-vector x.

The smaller Lie algebras have these isomorphisms:

SO(2) ~ U(1)
SO(3) ~ SU(2)
SO(4) ~ SU(2) * SU(2)
SO(6) ~ SU(4)

There are some additional Lie algebras, like the "symplectic" ones, Sp(2*n), and five "exceptional" ones: G2, F4, E6, E7, and E8.

I still think that's a maths mode and E6 is dangerously complicated to the point of having infinite solutions, which makes it again a theory of anything. Too complicated too background independant, or dependant and not experimental, to inferred from other models. Too indiscrete. Too bad.

The E6 theory that I mentioned is a superset of the Standard Model that lives in the familiar 4 dimensions, like most other GUT's:

Low-energy SM -> unbroken SM -> SU(5) -> SO(10) -> E6 -> E8 * E8 (string low-energy limit)

So this E6 GUT is not string theory.

[The Dagda]

I think that I'll review where we are about the Standard Model and possible GUT's, and see how string theory fits in.

The details are a bit arcane and lengthy, so I'm putting them in spoiler tags.

The short-short version -- one can get the Standard Model's multiplet structure out of string theory by a series of symmetry breakings.

Trigger Warning!!!1! :

I'll post in somewhat abbreviated fashion, but if anyone wants me to expand on it, I will.

At low energies (< a few hundred GeV), the gauge symmetry is SU(3) (QCD) * U(1) (electromagnetism)
I'll list the particles by (QCD multiplet, electric charge):

Higgs: at least one of (1,0), possible (1,+/-1)
Elementary Fermions: U (3,2/3), D (3,-1/3), N (1,0), E (1,-1)
Their antiparticles: U* (3*,-2/3), D* (3*,1/3), N* (1,0), E* (1,1)
Gauge: gluon (8,0), W (1,+/-1), Z (1,0), photon (1,0)

The unbroken Standard Model with two Higgs doublets, necessary for supersymmetric extensions of it:

The gauge symmetry is SU(3) (QCD) * SU(2) (weak isospin) * U(1) (weak hypercharge)

Left-handed Higgs: Hu (1,2,1/2), Hd (1,2,-1/2)
Right-handed Higgs: Hu* (1,2,-1/2), Hd* (1,2,1/2)
Left-handed EF's: Q (3,2,1/6), U* (3*,1,-2/3), D* (3*,1,1/3), L (3,2,-1/2), N* (1,1,0), E* (1,1,1)
Right-handed EF's: Q* (3*,2,1/6) U (3,1,2/3), D (3,1,-1/3), L* (3*,2,1/2), N (1,1,0), E (1,1,-1)
Gauge: gluon (8,1,0), W (1,3,0) (weak isospin), B (1,1,0) (weak hypercharge)

With supersymmetry, the Higgses and the EF"s form "Wess-Zumino" multiplets, with spins 0 and 1/2. The gauge particles have spins 1 and 1/2.

-

The simplest GUT with a single gauge multiplet is the SU(5) Georgi-Glashow model. Its particle content is

Higgs:
Left: Hu(5) = Hu + Hql (3,1,-1/3)
Left: Hd(5*) = Hd + Hqr* (3*,1,1/3)
Right: Hu(5*) = Hu* + Hql* (3*,1,1/3)
Right: Hd(5*) = Hd* + Hqr (3,1,-1/3)
EF's:
Left: F(1) = N*
Right: F(5) = D + L*
Left: F(10) = Q + U* + E*
Right: F(10*) = Q* + U + E
Left: F(5*) = D* + L
Right: F(1*) = N
Gauge:
G(24) = gluon + W + B + XY (3*,1,5/6 ) + XY* (3,1,-5/6)

The Georgi-Glashow model predicts some extra particles, which can cause proton and bound-neutron decay.
I'll give their low-energy multiplet values here:

A down-like "Higgs quark" (Hql, Hqr, Hql*, Hqr*): Hq (3,-1/3)
XY gauge particle: X (3*,4/3), Y (3*,1/3)

It has not only gauge unification, but also mass unification for down-like quarks and charged leptons. It has two Higgs multiplet pairs and three EF multiplet pairs per generation, not exactly one.


One can go further with a SO(10) symmetry. It will break into SU(5) * U(1) where the latter is related to B-L, (baryon number) - (lepton number).
I'll give the "B-L hypercharge" alongside the SU(5) multiplet number:

Higgs:
Left: H(10) = Hu(5,-2) + Hd(5*,2)
Right: H(10)* = Hu(5*,2) + Hd(5,-2)
EF's:
Left: F(16) = F(1,5) + F(10,1) + F(5*,-3)
Right: F(16*) = F(1*,-5) + F(10*,-1) + F(5,3)
Gauge:
G(45) = G(24,0) + G(10,-4) + G(10*,4) + G(1,0)

The SO(10) model has some additional particles, which are all gauge particles.

The Higgses are in one multiplet pair, and the EF's are in one multiplet pair per generation. This not only makes mass unification for all the EF's, it prevents cross-generation decay.

So we've reduced the Standard Model to 9 multiplets. Can we go further?

We can, with a bigger symmetry called E6, which breaks down into SO(10) * U(1)

Higgs + EF's:
Left: F(27) = F(16,1) + F(10,-2) + F(1,4)
Right: F(27*) = F(16*,-1) + F(10,2) + F(1,-4)
Gauge:
G(78) = G(27,0) + G(16,-3) + G(16*,3) + G(1,0)

One of the F(10,-2), F(-10,2) pairs becomes the SO(10) Higgses -- the other two must get GUT-scale masses. This may explain part of the mass pattern of elementary fermions -- the Higgses may live in the generation with the tau lepton, bottom quark, and top quark, with some "cross talk" due to symmetry breaking.

This has gotten down to 7 multiplets. Can we proceed further?

String theory to the rescue.

All the five kinds of superstrings have a supergravity multiplet in their low-energy limits, and some of them also have a gauge-field multiplet in those limits. The possible gauge symmetries are constrained by quantum-mechanical consistency to SO(10) and E8*E8; their superstrings are types HO and HE.

Superstrings prefer to live in 10 space-time dimensions, so it's expected that 6 of them will compactify, becoming a GUT-to-Planck-sized ball. This is also a kind of symmetry breaking, it must be said.

This compactification will interact with the gauge field, breaking one of the E8's to E6 * SU(3):

Gauge:
G(248) = G(78,1) + G(1,8) + G(27,3) + G(27*,3*)

Thus, *all* the Standard-Model particles emerge from *one* gauge multiplet, three generations and all. The spin-0 ones get their spin reduced from 1 as a side effect of compactification.

That ball will also induce further symmetry breaking, the details of which are dependent on its topology. It can have numerous possible topologies, thus producing numerous possible symmetry-breaking patterns.

Even if one of them could be shown to produce the entire Standard Model, one then feels compelled to ask: why that one and not another one? There does not seem much of a hint in string theory as to which one might be "preferred".

Interesting total mathematical waffle and impenetrable but interesting.

I still think that's a maths mode and E6 is dangerously complicated to the point of having infinite solutions, which makes it again a theory of anything. Too complicated too background independant, or dependant and not experimental, to inferred from other models. Too indiscrete. Too bad.

I've heard E6 theories that aren't string theory are even more complicated and unlikely than strings itself. I don't doubt it makes perfect sense to those studying that sort of maths, I just wonder why anyone would want to study that sort of idea myself. Unimaginably complicated and boring IMHO. the Universe we can see is interesting, maths for its own sake is not. But then I am not a mathematician.



Good god no, why?

By the way don't let my contempt for E6 as science if not respect for its maths give you the impression I am expecting you to defend it or care to much beyond the equations themselves.

[kiki5711]

"Equations that begin brilliantly and end in wishful thinking" -- 'Hannibal'

Hannibal the Cannibal?

back to square one.

[The Dagda]

"Equations that begin brilliantly and end in wishful thinking" -- 'Hannibal'

Hannibal the Cannibal?

back to square one.

Probably the Emperor Hannibal of Carthage? No idea?

String Theorists Finally Admit Defeat
April 1st, 2004

The news that next week’s “Science Times” will run an article by NYT reporter James Glanz in which several leading string theorists say that they are giving up on the idea is rapidly spreading throughout the particle theory community. Evidently Glanz recently went down to Princeton to interview Edward Witten, who took the opportunity to announce that he has changed his mind about whether string theory will ever be a “Theory of Everything”. When Glanz contacted other string theorists and read to them what Witten had said, almost all of them told him that they too had been having their doubts about the theory.

Glanz quotes Witten as follows:

“One night a few weeks ago I was sitting at my kitchen table trying to make sense of Douglas’s latest work on the KKLT proposal and all of a sudden it really hit me that this is a completely lost cause. If perturbative string theory has any relation to Planck scale physics, then KKLT or something like it should work and string theory is vacuous since it can never predict anything. If perturbative string theory isn’t useful then we really don’t have anything since we’ve never been able to come up with a non-perturbative version that makes sense. Twenty years of this is enough. It’s time to give up.”

When Glanz asked him what he intends to do now, Witten responded:

“I don’t really know. There are still promising ideas about using string theory to solve QCD, and I could keep working on those. Maybe I should take up something completely different, like biology. I’m starting to worry that John Horgan was right about the ‘End of Science’. Right now I just definitely need a long vacation.”

When Glanz read Witten’s statement over the phone to David Gross, Frederick W. Gluck Professor of Physics at UCSB and Director of the Fred Kavli Institute for Theoretical Physics, Gross thought for a moment and then told him “Yeah, despite my quote last year from Churchill, I’ve also been thinking of giving up. Not sure though how I’m going to break this to the two Freds.”

The news of Glanz’s article has had dramatic effects at many universities and research institutes. At MIT yesterday, Prof. Barton Zwiebach shocked students in his Physics 8.251 “String Theory for Undergraduates” class by announcing that he wasn’t going to collect the homework due that day and was canceling his lectures for the rest of the semester. He also asked Cambridge University Press to halt publication of his new undergraduate textbook called “A First Course in String Theory”, the release of which had been planned for next month.

Search committees at several institutions that hadn’t finished their hiring yet this season held new meetings to decide how to react to the news. A prominent theorist at a UC campus told me in an e-mail that “our chair had the phone in his hand and had already dialed the number of a string theory graduate student from Princeton we were going to offer a post-doc to. I ran into his office as soon as I heard the news and stopped him just in time. Last week we were sure that string theorists were the smartest guys around and considered only them for jobs, but now there’s no way we’re going to hire any more, ever!”.

At the Institute in Princeton this year’s “Summer Program for Graduate Students in String Theory” scheduled for July has been canceled, with one of its organizers remarking “what graduate student would now be crazy enough to show up for a program like this?” Next week’s conference on “The Status of M-theory” at the Michigan Center for Theoretical Physics has also been canceled on very short notice. The director there, Michael Duff, commented “We had to do this because the status of M-theory is all too clear. It’s passed on! This theory is no more! It has ceased to be! It’s expired and gone to meet its maker! … This is an ex-theory!”

Breaking news. Well it was 4 years ago I wonder where strings are now? Yes the piece is clearly biased but the information seems credible.

Smolins blog.

[newolder]

Breaking news. Well it was 4 years ago ...

An “All Fools Day” report from 2004?
You've got to be kidding, right?

[Nautilidae]

Ahhh diddums. You think anything they say is taken seriously by those outside of string theory and I don't think it is mainstream. /thread

Yes. That's why it's in a science journal.

You have adressed the premisis but what you are saying is garbage and not true, every time you say it it becomes more and more a mantra of dogmatic belief.

You say that but I have shown peer-reviewed work that shows that it isn't garbage. Of course, you will simply ignore it, claiming that it's either lying or biased.

The reason being is that I don't even think you know what you are saying means. You are just quoting something you read because you have no idea how field theories actually work.

Let's disregard the fact that I understand the basics of field theory to prove a point. What does that do to support your argument? Does my understanding of a statement or claim make it any less true or false? No it does not.

Explain to me how curled up dimensions can be detected, how variations are discreet and exactly how they are and could be shown in precise mathematical terms that give a discrepancy in a constant agreed by peer review that would make it unlike other models standard or x?

In extra-dimensional theories, the Planck mass, an important value in physics, shrinks. The Planck mass is reduced to the TeV energy scale, a scale accessible at the LHC. Because of this small Planck mass, massive objects such as micro black holes and string-balls can be created at lower energies. In fact, there is a peer-reviewed paper that shows that micro black holes and string-balls created in this manner can give rise to the Higgs boson.

Curled dimensions date back as early as the 1940's when a physicist named Theodore Kaluza proposed a 5-dimensional variant of general relativity that gave rise to electromagnetism. Oscar Klein proposed that the 5th dimension of Kaluza's theory was curled up, or compactified.

Compactification is how one reduces a theory's number of dimensions while still keeping that dimension in tact.

To get a 10-dimensional space that , to large objects, *looks* 3+1 dimensional, one begins with a 3-dimensional manifold M4. This represents our 3+1 dimensional Minkowski space-time, so it is labeled with a "4" to represent 4 dimensions.

One then multiplies it with a Calabi-Yau 6-manifold to get a space of this form: M4xC6. One constructs a fiber bundle f: E -> M4 with C6 being the fiber. This maps a Calabi-Yau manifold to every point in the Minkowski space-time. The size of these Calabi-Yau manifolds is the Planck length, so the fiber bundle describes space-time as viewed by strings. How one compactifies the 6 dimensions can give rise to different effects, but this is the basic method. Other methods involve different varieties of Calabi-Yau manifolds, such as a 4-manifold with elliptical fibers in the shape of a 2-torus.

Extra dimensions, as far as math is concerned, isn't very complicated.

I really couldn't give a damn what you think (because you have no idea what anything you are saying actually means to an experiment) or anyone inside string theory thinks is true by default of them saying it is in the face of criticism, the fact is they aren't getting Nobel prizes and its likely they never will. So that's all that matters to me. The fact that the mainstream spurns their pseudo hypothesis as lacking in weight says more than anything ever could from the bouncy castle ridden fantasy land that is Imagination land where maths is real. Anything you have read that claims to make string theory a stand alone theory is a fraud made by the chancers in science, the people who just say something that isn't true again and again and again as if saying it again and again and again will magically make it more true.

This is priceless.

First, you ask me to explain something and then immediately tell me that you don't give a damn what my answer is. These two statements, when combined, render your argument utterly vacuous.

Following this, you claim that math is only real in fantasy land. In case you haven't noticed, for the past two thousand years, mathematics has done a very fine job of defining reality and nature. This can be seen in something as simple as Newton's laws of motion to something as complex as general relativity.

THEN you create a conspiracy theory that everyone that publishes work that discredits your arguments is committing fraud. You have no evidence of this, and you probably never will.

Theory Failure #1: In order to make string theory work on paper our four dimensional real world had to be increased to eleven dimensions. Since these extra dimensions can never be verified, they must be believed with religious-like faith -- not science.

Incorrect, as shown many times throughout this thread.

Theory Failure #2: Since there are an incalculable number of variations of the extra seven dimensions in string theory there are an infinite number of probable outcomes.

While this is true, the point he is making is null. The varieties of string theory compactifications don't necessarily lead to consistent descriptions of the universe. For instance, there are Lie algebras that can be used to describe certain properties of a string theory but aren't consistent with nature. These can be ruled out. The point he is making is that there are many different string theory vacuums. However, only one of them correctly describes nature. This is analogous to any theory that hasn't been tested. It may be consistent, like Nordstrom gravity, but it isn't necessarily seen in nature. By making predictions that match nature, the theories that don't match the results can be thrown away. Of course, you'll simply say that string theory makes no predictions, which is typical and false.

Theory Failure #3: The only prediction ever made by string theory -- the strength of the cosmological constant -- was off by a factor of 55, which is the difference in magnitude of a baseball and our sun.

This is facile. This is not a flaw of just string theory, but most quantum field theories. Plus he makes the assertion that this is the only prediction made by string theory, which has been shown to be incorrect.

Theory Failure #4: While many proponents have called string theory "elegant," this is the furthest thing from the truth. No theory has ever proven as cumbrous and unyielding as string theory. With all of its countless permutations it has established itself to be endless not elegant.

This is vacuous. Despite the fact that it is filled with opinionated statements, I've already shown this to be an incorrect argument.

Theory Failure #5: The final nail in the coffin of string theory is that it can never be tested.

That's funny. He claims that string theory can never be tested, yet he claims in an earlier argument that string theory made a testable prediction. This is inconsistent. I've also shown this to be false.

The rest isn't even worth addressing. The very premise of the final section has already been shown to be incorrect.

Can anything insinuate itself into your impenetrable faith at all? Even maths even deeply understanding string theory? Even the words of the brightest and best who aren't religious devotees with everything to lose?

Can anything allow you to make coherent arguments? Ones that don't involve arm-waving or opinionated statements? Even the fact that we've given you several chances to do so but still respond with the same facile, ad hominem ridden arguments??

The last quote made arguments that I've already addressed, so I won't bother dealing with it.

Breaking news. Well it was 4 years ago ...

An “All Fools Day” report from 2004?
You've got to be kidding, right?

If this is true, I am very disappointed in you, Dadga. The Smolin quote isn't even worth addressing if this is the case.

- Nautilidae

[newolder]

...

Breaking news. Well it was 4 years ago ...

An “All Fools Day” report from 2004?
You've got to be kidding, right?

If this is true, I am very disappointed in you, Dadga. The Smolin quote isn't even worth addressing if this is the case.

- Nautilidae

http://www.math.columbia.edu/~woit/wordpress/?p=9

This entry was posted on Thursday, April 1st, 2004 at 10:08 am and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.
…
Peter says:
April 2, 2004 at 11:36 am
“Just wondering–and no disrespect meant–is this an April Fools Day joke?” (quoted from raj)
Ummmm, yes. Some people think it was rather too subtle, some not.
“I heard from Harvard yesterday that Lubos Motl has decided to take up professional wrestling now that his job there is being cancelled.” (quoted from zeitblom)
I had thought about including news about Lubos, but he is pretty hard to parody.

[The Dagda]

If this is true, I am very disappointed in you, Dadga. The Smolin quote isn't even worth addressing if this is the case.

- Nautilidae

I see you have no sense of humour either.

So I'm right you can't explain to me why it is or isn't testable I think we're done here then.

You basically side with String Theorists and I with the mainstream lets see who's right eh? I don't think you really understand what you are defending tbh though.

"This is false" as an argument highlights only your lack of understanding of that which you are defending. Why is it false what experiment can and will distinguish strings and why?

That's funny. He claims that string theory can never be tested, yet he claims in an earlier argument that string theory made a testable prediction. This is inconsistent. I've also shown this to be false.

The rest isn't even worth addressing. The very premise of the final section has already been shown to be incorrect.

Oh shut up you're an ill educated school boy what the hell do you know. I wouldn't of presumed to tell people with more qualifications than me what physics is the fact you do is sad. The fact that just saying this is facile about some professional scientists is enough for you to have argued the point shows that you really do have no idea even why you believe what you do, it's just what you were told by propagandists.

Do you understand Euclidean geometry, imaginary numbers, general and special relativity: Non Euclidean geometry, vectors, tensors any maths that relates to physics at a level where you can begin to understand the underlying concepts, feild theory basic concepts? If not then there's little point exploring why String Theorists are so convinced of their fairies. And there's little point in continuing this discussion. That's not an ad hominem ,that's just being at a stalemate because you don't have the education to argue further. Now I'm not claiming to be an expert far from it but I do understand what the objections are at a higher level than the 15 years olds curriculum.

Balls in your court I'll give you 24 hours to show me any sign you know what it is that makes string theory testable and how it is provable and then I'll assume you can't. I can't argue with papers that are hypothetical, that's what experiment is for.

I wouldn't begin to try anyway, its a waste of time a hypothesis is only as good as it's peer review.

[owtth]

Oh shut up you're an ill educated school boy what the hell do you know. I wouldn't have presumed to tell people ....

If you're going to belittle somebody's education it's generally best to get your grammar right.