Martin Veltman gave a colloquium talk at Fermilab two weeks ago and, as usual, had some very provocative comments to make. At the end of his talk he made the claim that the only thing astrophysics has contributed to particle physics is information about the number of neutrinos (from Helium abundance observations). He claims “Apart from this, Astrophysics is so far useless to us.”

He then gave some purported data about how particle physicists really felt about the impact of astrophysics and cosmology on their field. His slides say:

“Question put to many particle physicists: Do you feel that astrophysics and particle physics are joined at the hip?

Response:

Refusing to respond on the grounds that it is an obscene proposition (99.9%)

Do not know what you are talking about (9.671%)

Undecided (rest)

Questions put to particle experimenters:

Your experiment is justified by claiming that it will tell us about the first seconds of the big bang. Do you agree?

Response:

No (98.312%)

Do not know what you are talking about (1.671%)

Undecided (rest)

Do you feel that we need a new machine (linear collider) because it can be used to discover dark matter (dark energy)?

Response:

No (98.312%)

Do not know what you are talking about (1.671%)

Is this related to the death star of Darth Vader? (3%)

Undecided (rest)”

I think Veltman has a very good point. The particle physics community seems to have decided to try and sell the public on supporting particle physics, specifically a new linear collider, by claiming that such a machine will “solve the mystery of dark energy”, find “extra dimensions of space”, and tell us “how the universe came to be” (see for instance the HEPAP Quantum Universe report). This all sounds very sexy, but there’s no good reason to believe that a linear collider will do any of this. Maybe this is the right way to sell the linear collider, but personally I’m rather uncomfortable with this level of hype and wouldn’t want to be the one testifying under oath before Congress about this.

Veltman also comments that “It appears to me that the only viable solution is that this machine will be located in the US”, but given the massive deficit the Bush administration has created and current political realities, I find it hard to believe we’ll see the kind of budget increases for particle physics that would be required to make this happen anytime soon.

Since in 1 dimensions everything is pretty simple these susy field theories in 1+0 dimensions are not awfully exciting and you can get away with ignoring the susy that appears here.Or you may be inspired by it.

The question is for how many years, decades and centuries inspiration is enough. Signatures for supersymmetry have had ample opportunity to show up in quite a few different types of experiments, in the 1/3 century that has passed since SUSY was proposed. No such signatures have been found. A common way of summarizing the experimental situation is to say that SUSY requires fine-tuning on the percent level. This seems like a serious critique of an idea which was mainly meant to cure fine-tuning.

Anyway, we evidently have different opinions about how much inspiration should be constrained by experiments. I would like to know one things, though. The discovery of sparticles at the LHC would obviously be a great triumph for SUSY, and it would prove me dead wrong in many ways. But do you think that the non-discovery of sparticles at the LHC would in any way lessen the promise and importance of SUSY?

,

Thanks, that was very interesting, and you have an excellent way of explaining things (I imagine because you actually understand it).

-drl

Hi DRL –

Ok, well, I am not going to try to further explain why {D,D} = 2Box is the algebra of worldline susy. Whoever does not believe it should check the standard literature.

Concerning your question:

There is nothing artificial (‘clever’) going on, I think. The point is that the standard Polyakov-like action of the single free relativistic particle is, when regarded as a theory defined on the worldline, a 1+0 dimensional field theory of a couple of bosonic fields (the coordinate fields) coupled to a lagrange multiplier in such a way that the whole thing can be regarded as 1+0 dimensional gravity coupled to massless scalars plus a ‘cosmological’ constant – on the worldline.

This is just a fact. This action is there and it describes known physics (for instance you can compute QFT loop amplitudes

in target spacefrom it) and it has this interpretation as a 1+0 dimensional field theory.When this 1+0 dimensional field theory is susy-ed, which means that in addition to free bosons we allow free massless fermions propagating on the worldline, it gives us the action for single fermions in target space.

Up to this point one is firmly in the realm of known physics. All that has happened is that one has realized that single particle trajectories have field theoritic descriptions on the worldline – and supersymmetric field theories in particular. (Check Siegel’s book for instance for the superfield formulation of them.)

Since in 1 dimensions everything is pretty simple these susy field theories in 1+0 dimensions are not awfully exciting and you can get away with ignoring the susy that appears here.

Or you may be inspired by it. Turns out that in 1+1 dimensions susy field theories are still pretty simple, but taken as theories on the parameter space of single objects again (as we did before for the worldline), they are not just a curiosity but give rise in target space to perturbatively quantized superGR+YM.

This automatism that you cannot have a worldsheet which describes target space fermions without having it supersymmetric and hence have the target space theory supersymmetric is the reason why people say that string theory ‘predicts’ supersymmetry.

But one has to interpret this carefully. Just having the target space theory being supersymmetric (locally) does not mean that its physically relevant solutions exhibit this symmetry, as you know. Hence while the assumption of strings sort of ‘predicts’ that the world is locally supersymmetric, it does not (necessarily) say anything about the observability of globally supersymmetric solutions (which would give rise to superpartners observable in accelerators).

So, to make it very clear once again: Nothing of what I have said here is meant as a proof that target space supersymmetry exists. But since worldline supersymmetry does exist (since it is so trivial) the concept of supersymmetry seems very natural from some point of view. Even more since in 1+1 dimensions worldsheet susy does imply target space susy (while in 1+0 dimensions it only implies target space fermions.)

Make of that what you want.

“Bow out?” Why? this is very interesting and at least for me informative.

RE p. 134 – OK fine, now I see what you were getting at – but isn’t this just a clever jamming together of actions, one of which alone would lead to the Dirac (neutrino) equation and the other to a free classical particle?

-drl

As I said, when you go from the vector fields to their Noether charges of the sigma model you get the quadratic terms (like (partial phi)(partial phi) for the Polyakov action).

The Dirac operator as well as its square that we are talking about all along are Noether charges of a sigma model action that come from vector fields of the sort that you are talking about.

As I said, you should consider the simple case of nonrelativistic supersymmetric quantum mechanics to clarify the picture.

There is one of your vector fields, namely d_t on the worldline. Its charge is the Hamiltonian H. You can write down the square root of d_t as usual, to get the ‘covariant’ superderivative D that satisfies {D,D} = i d_t . The charge associated with D is the supercharge Q. This has Poisson bracket {Q,Q} = 2H, giving the same algebra as your vector fields.

To summarize:

There are symmetry generators which are vector fields on super-parameter space and satisfy

{D,D} = i d_t ,

where the bracket is the super-Lie bracket of super-vector fields

These have associated conserved charges which have the Poisson bracket

{Q,Q} = H ,

which is the same algebra as that of the symmetries they come from (which is no surprise).

For the relativistic particle it is precisly analogous, only that here t becomes an unphysical parameter tau and H becomes a constraint (the KG operator).

All this is elementary and standard. I’ll bow out at this point.

The {D,D} = 2Box algebra is just a truncation of the super-Virasoro algebra and there, too, as you know, L + \bar L is quadratic in derivatives.There is some confusion here. The even generators of the super-Virasoro algebra are the vector fields

L_m = z^(m+1) d/dz + f_m z^m \theta d/d\theta,

which are first order (I don’t want to work out the constants f_m). L_0 is certainly not second order, not even if you add \bar L_m.

In fact, the superconformal algebra is the algebra of vector fields in superspace which preserve the contact one-form

\alpha = dz + \theta d\theta

up to a function. Vector fields are always first-order differential operators; this is the definition of a vector field.

We can also realize super-Virasoro as an infinite sum of bilinears, like

L_m = sum_n :a_n a_(m-n): + (n + km) :b_n c_(m-n):

i.e. as a subalgebra of gl(infinity). These may be viewed as vector fields acting on an infinite-dimensional vector space whose coordinates are modes with positive energy (m>0), and the negative-energy modes are derivatives. With that interpretation, some of the L_m’s contain terms that are zeroth or second order, but L_0 only contains first-order terms.

Danny –

Read on to p. 134. See exercise IIIB1.2 .

,

RE p. 132 of Siegel – all I see is typical particle actions on a trajectory. What does this have to do with KG and “adding Fermions”?

-drl

Thomas,

Regarding the third string revolution: a minimal requirement for a something to qualify as a revolution is that outsiders notice it. Most physicists of all kinds noticed that many particle theorists started to talk about strings in 1984, about branes in 1994, and about antropic selection in 2003. Much fewer outsiders, if any, has noticed the emergent spacetime.—

Lubos,What do you think will be the main ideas which will propel the “third” superstring revolution starting next year? Hopefully it will be something which does not involve the anthropic principle.

Posted by JC at October 9, 2004 10:24 AMI have to give credit where credit is duein reference to Third Superstring Revolution

Identifyng this translation is necessary?

Thomas –

don’t mistake the symmetry generators in the Lagrangian, like partial_mu, with their corresponding Noether charges which generate them by means of Poisson brackets. Box is the (quantized) Noether charge of the partial_tau translation symmetry on the worldline and has no reason to be linear in derivatives.

So sure {D,D} = 2Box is a susy. Box is the wordline ADM Hamiltonian. And you really new this: The {D,D} = 2Box algebra is just a truncation of the super-Virasoro algebra and there, too, as you know, L + \bar L is quadratic in derivatives.

I bet once you think about this in terms of the nonrelativistic particle this becomes clearer: The Hamiltonian is quadratic in the momenta and still it generate time evolution.

And if you like, you can surely do some field theory using just worldlines, just like you compute string amplitudes just using worldsheets. This is known as the ‘worldline technique’ for field theory. See for instance vanHolten’s hep-th/9408027 and references given there.

DRL –

N is a Lagrange parameter, the lapse function on the worldline, i.e. the single component of the worldline metric. It’s presence makes this action equivalent to the (maybe more familiar?) NG-like action of the free particle.

All this is explained in introductory textbooks. For instance look at pp. 132 of Warren Siegel’s book “Fields”, which you can download for free at

http://www.imsc.ernet.in/physweb/Fields.pdf

Particles on a world-line is first quantization – that formalism cannot account for creation and annihilation of particles. People invented something called quantum field theory to cure that defect in the late 1920s.

To consider the appearence of superalgebras as a hint of SUSY seems to me like a very long shot. {D,D}= Box and Box commutes with everything is a superalgebra, which is relevant for fermions and spinors whose physical relevance nobody has denied. This is not a supersymmetry because the d’Alembertian is a second-order differential operator, whereas in {Q,Q} = P_mu the RHS is a translation, i.e. first order.

However, I appreciate that people try to apply beautiful mathematical structures to physics, although most of the beauty of SUSY is inherited from its superalgebra structure. In fact, I discovered the higher-dimensional generalization of the Virasoro algebra because I wanted to apply it to quantum gravity. We now know that such an algebra exists and that it has a wonderfully beautiful representation theory which seems to fit the needs of quantum gravity exactly. This indicates to me that my original physical motivation was correct. So mathematical beauty is certainly an important search criterion, but it can never be a success criterion by itself. Even if EW says that it is magic and mystery.

It would of course be nothing wrong with SUSY, had it been seen in experiment. However, there are just too many experiments that should have seen signatures of SUSY but did not. The absense of sparticles is the most obvious one, but SUSY also suggests a light Higgs, proton decay, permanent electric dipole moments, WIMPs, a deviation in muon g-2, etc. None of these things have been seen, at least not conclusively, which to me is a clear indication that SUSY just isn’t there.

I guess that my position is similar to Veltman’s, expressed e.g. at the end of his book:

“The fact is that this book is about physics, and this implies that the theoretical ideas discussed must be supported by experimental facts. Neither supersymmetry nor string theory satisfy this criterion. They are figments of the theoretical mind. To quote Pauli: They are not even wrong. They have no place here.”

I didn’t make up this quote; it can be found in one of the reviews at the amazon.com link. Do you really think that you or your physics professor are competent enough to question the opinion of a Nobel laureate in theoretical particle physics?

Regarding the third string revolution: a minimal requirement for a something to qualify as a revolution is that outsiders notice it. Most physicists of all kinds noticed that many particle theorists started to talk about strings in 1984, about branes in 1994, and about antropic selection in 2003. Much fewer outsiders, if any, has noticed the emergent spacetime.

..so this L is 1/2N (ds^2 – m^2 N^2) ?

What happened to (grad N)^2 (Klein-Gordon)?

-drl

Do you understand how the Klein-Gordon particle is described by the action

S = (1/2)\int dtau (N^-1 \dot X^m \dot X_m – Nm^2)

and how this action can be regarded as 1+0 dimensional ‘gravity’ coupled to scalar ‘matter’ (just formally)?

No I don’t – “what” are you “adding”, and to “what”? Explain it to me, without repeating the last two posts. Just jot down a few comments and I’ll interpolate.

From my perspective, a Dirac particle is a solution to the Dirac equation in the usual Fock space treatment. It is a primitve object. Explain to me how it is not a primitive object. I don’t know what you mean by “on the world-line” and so on.

-drl

Do you know how the relativistic bosonic particle is described by a field theory of massless bosonic fields on the worldline (a 1-dimensional sigma-model)?

If you add massless fermions to such a field theory on the worldline it becomes supersymmetric on the worldline (a 1-D susy sigma model) and now describes fermions in target space instead of (or in addition to, depending on some details) bosonic particles.

a) if you regard the massless Klein-Gordon particle as a 1+0 dimensional bosonic field theory on the worldline and add fermionic fields on the worldline to it in order to get target space fermions (the Dirac particle) the worldline theory automatically becomes supersymmetric..Umm.. what exactly does this mean?

-drl

Thomas –

recall the previous discussion. Steve M said about

superalgebras appearing in nuclear physics:

It was then said that if you are willing to take the mere appearance of superalgebras as a hint that supersymmetry will play a more important role (which you, Thomas, are not, but others might be) that then it would be ‘more’ interesting to consider worldline susy which indeed exists.

As you indicate by your reaction, and as was not disputed by anyone, this worldline susy is rather trivial and hardly a hint for anything.

But some people may find it amusing to note that

a) if you regard the massless Klein-Gordon particle as a 1+0 dimensional bosonic field theory on the worldline and add fermionic fields on the worldline to it in order to get target space fermions (the Dirac particle) the worldline theory automatically becomes supersymmetric

b) if you regard the bosonic string as a 1+1 dimensional bosonic field theory and add worldsheet fermions to it in order to get target space fermions the worldsheet theoy automatically becomes supersymmetric (this is how susy was found in the western hemisphere) and is quantumly consistent only if the target space solves susy GR+YM

c) if you regard the bosonic membrane as a 1+2 dimensional bosonic field theory and add worldsheet fermions to it in order to get target space fermions the worldvolume theory becomes supersymmetric and is classically consistent only if the target space solves susy GR+YM .

This is not a proof for anything and if you don’t like it you are welcome to ignore it.

Others may find it noteworthy that while spacetime susy is a delicate issue, woldvolume (-line, -sheet) susy is inevitable, since in low dimensions adding massless fermions to massless bosons is (almost) bound to give susy, as is exemplified by the boring old Dirac particle. And here a small step in parameter space (going from 1+0 to 1+1) is a large step in target space (going from nothing at all to susy-GR+YM).

Thomas,

Plato, the Third Superstring Revolution, also known as the Anthropic Revolution, happened in 2003. The interpretation is that experimental agreement is now irrelevant. String theory is correct even though it disagrees with observation, because God created the Universe to be compatible with human life.One thing I can tell you, though, is that most string theorist’s suspect that spacetime is a emergent Phenomena in the language of condensed matter physics.

WittenI developed a post today on my blog, in response to your statement. Sometimes, the very language one uses, orders the sequences of thought in another way? I present this to you in this light, and hope you will read post when it materializes later.:) I am learning.

The substance of the official

Third Superstring Revolutionwas posted on this Blog and officially(I recogize your statement) raises the line I have used of Witten.Would you agree to entertain the

Third Superstring Revolutionin this way?I might ask you then, that if this language had been changed, then what would the professor crossing the room mean? One would have look to what is materializing from condensed matter physics, by what is being presented, by Robert Lauglin. You see?

Anonymous, the electron can to a good approximation be considered a free Dirac particle. The electron was discovered in 1895 and supersymmetry around 1970. Maybe this is an indication that having a Dirac particle is not sufficient for supersymmetry. However, I find it quite likely that electrons will be found at the LHC. If you wish, you may hail that as proof for supersymmetry.

Plato, the Third Superstring Revolution, also known as the Anthropic Revolution, happened in 2003. The interpretation is that experimental agreement is now irrelevant. String theory is correct even though it disagrees with observation, because God created the Universe to be compatible with human life.

Hi DRL, {D,D} = 2 Box ! ðŸ™‚

Is it nice that Veltman recieved award with Gerard t Hooft in 1999? Is this correct?

IN response to Peter’s post I posted about five threads in relation to what Peter and others might reconsider, as to the question of how we might look at quantum computerization(non)?

With the Third Superstring Revolution, what shall emerge from a change in Fundamental interpretation of Quantum Mechanics?

I’m sorry, but there is no Bosonic context for a Dirac particle. There is the old “neutrino theory of light” but those are not Fermions because of an implicit correlation that ruins the statistics.

Perhaps you could scribble here a few lines about the claim

infra.If one really wanted to see ‘formal’ evidence for spacetime supersymmetry as in

I would suggest to take the Dirac particle. It has worldline 1+0 dimensional N=1 supersymmetry in the ‘right’ sense. There is a Hamiltonian constraint which generates time evolution (the Klein-Gordon operator) and the Dirac operator is the corresponding supercharge.

This might be a coincidence of low dimensions. But one might take it as a ‘hint’ for spacetime susy that by just going from this worldline susy to an analogous worldsheet susy yields spacetime susy GR+YM .

By definition, a Lie superalgebra is like a Lie algebra, except that some brackets are fermionic, so

[even, even] = even

[even, odd] = odd

{odd, odd} = even

A supersymmetry is a particular kind of superalgebra where some of the even generators can be identified with spacetime translations. Whereas superalgebras are a very beautiful and far-reaching generalization of Lie algebras, the extra translation condition that makes it into a supersymmetry does not seem particularly interesting.

But the two concepts are often blurred, as in the case of gold nuclei. One reason seems to be that supersymmetry has been more heavily sold.

I dont’ see how you can have half a ball of wax. Please explain? How is it a superalgebra if

{Q, Qdot} not = some kind of translation

Perhaps I missed the definition of superalgebra.

-drl

Yes, this ‘supersymmetry’ operation between nuclei has nothing to do with whether the (effective) field theory that describes the particles and interaction in our world enjoys symmetry under a graded extension of the Lorentz group (locally).

Graded algebras and Grassmann parameters are just concepts useful enough that they show up all over the place, not necessarily in the context of supersymmetry in high energy physics.

For instance in statistical physics many people will tell you that they are using ‘supersymmetry methods’ to evaluate their free energy or something. What they really do is conveniently express determinants as Grassmann integrals. So this method should rather be called a ‘BRST-like method’. It has nothing to do with spacetime supersymmetry, either.

Of course some people feel inclined to argue that any piece of sufficiently nice mathematics should play a role in a TOE…

To answer drl’s question regarding what physical evidence points to supersymmetry, “nuclear supersymmetry” has been observed and verified experimentally. At Yale in 1990 it was suggested that supersymmetry effects might be seen in nuclear physics. A super-algebra was proposed that allows a nucleus with even nos of protons and neutrons(even-even), 2 nuclei with even nos protons/odd nos. neutrons (even-odd)and odd nos protons/even nos neutrons (odd-even), and an (odd-odd) to transform into each other via this supersymmetry algebra. Platinum-194(even-even), gold-195(odd-even) platinum-195 (even-odd) and gold 196(odd-odd)form such a supersymmetric quartet.From what I’ve heard, this is not a supersymmetry, but rather an internal superalgebra symmetry. No bosonic subalgebra can be identified with spacetime transformations, which is the definition of a supersymmetry. An internal superalgebra symmetry does not necessarily imply superpartners of equal mass.

A genuine supersymmetry seems to exist in the tricritical Ising model in 2D, however; this is the CFT with c = 7/10. It is unclear to me what this supersymmetry corresponds to in experimental realizations such as a monolayer of Argon atoms on an inert graphite substrate.

Finally, I doubt that Lubos Motl will stay in his restroom for the rest of his life when no sparticles are found at the LHC. On the contrary, he will aggressively explain how absense of sparticles and extra-dimensions confirms that string theory is correct.

Steven M,

That’s interesting, it means that SuSy works as a dynamical symmetry (like say isospin for a simple nuclear model). Of course it doesn’t imply that the actual Bosons and Fermions of the world are related this way.

In the experimental situation described, how does the anticommutator

{Q_r, Qbar_sdot} = 2 sigma^a_r_sdot P_a (P_a = translation)

show up physically?

I don’t want to comment on how much particle physics

has contributed towards astrophysics. One thing however is certainly true. in the last decade many experimental high energy physicists have switched over to astrophysics/gravitation experiments such as LIGO, GLAST, supernova csomology, CMB

experiments, TeV gamma ray astronomy experiments,

uhe cosmic rays, etc.

If no evidence for physics beyond the standard model is found by the time LHC starts I

expect more high energy physicists to switch over

to astrophysics. Also both Fermilab and SLAC

have set up astrophysics groups.

OTOH I don’t know of a single example of an astronomer switching over to experimental high energy physics or

national astronomy institutes such as NRAO setting up a high energy physics group.

Lubos Motl said: “I don’t care too much about dark matter – and I would agree with Veltman that the influence of astrophysics on theoretical high-energy physics has been small”.

Just to clarify: we string theorists don’t really care about dark matter and ESPECIALLY — Sean — we don’t care about so-called dark energy. String theory clearly favors a negative cosmological constant, so all current observations suggesting a positive one are clearly wild monkey speculations that have no connection with reality. String theory likewise says nothing at all about dark matter, so obviously it doesn’t exist.

To answer drl’s question regarding what physical evidence points to supersymmetry, “nuclear supersymmetry” has been observed and verified experimentally. At Yale in 1990 it was suggested that supersymmetry effects might be seen in nuclear physics. A super-algebra was proposed that allows a nucleus with even nos of protons and neutrons(even-even), 2 nuclei with even nos protons/odd nos. neutrons (even-odd)and odd nos protons/even nos neutrons (odd-even), and an (odd-odd) to transform into each other via this supersymmetry algebra. Platinum-194(even-even), gold-195(odd-even) platinum-195 (even-odd) and gold 196(odd-odd)form such a supersymmetric quartet. Given the energy spectra of gold-196 the supersymmetry algebra gives the spectra for the other 3 nuclei in the quartet. Verified in the lab now by several groups. Other supersymmetric nuclear quartets have been found. This doesnt “prove” supersymmetry of course but makes its realisation in nature in particle theory, seem a whole lot more likely.

See

http://physicsweb.org/articles/world/12/10/3

I believe expectations for the top quark mass were always “just around the corner”, creeping upwards year after year, until it was finally found. So there’s still hope.

Just to rain on Lubos’s parade a little bit, most of the phenomenology talks here over the past couple of months have started out with why the current bounds on the Higgs mass strongly disfavour the MSSM. They don’t rule it out, but it’s strongly disfavoured.

My understand of the history is that SUSY has been “around the corner, next accelerator” since it was first dreamed up.

I thought I would add this in the hopes of “expanding” current limitations in matter considerations.

http://eskesthai.blogspot.com/2004/11/sound-waves-in-cmb.html

So Motl,

What physical evidence points to SuSy? Name one thing. One.

-drl

Of course that it will be shocking when SUSY is found. It will be so shocking that the people who have fought against SUSY will have to hide in their restrooms for the rest of their lives, Thomas. ðŸ™‚

At least I can’t really imagine how could you be able to appear publicly on the internet after your teachings will be devastated beyond reasonable doubts, and after everyone will see that you were trying to return the humakind to the Middle Ages. ðŸ˜‰

Moreover, it’s pretty likely that it will happen! SUSY is gonna be found, it will be dramatic, and string theorists are ready to take credit for it. ðŸ˜‰

It’s easy to be provocative, as we know. If Veltman doesn’t think that astrophysics has contributed to particle physics, he must not care about the discovery of the muon, evidence for non-baryonic dark matter, dark energy, neutrino masses and mixings, constraints on everything from time-dependence of alpha to the mass of the photon, and just about all of general relativity. In the last thirty years, astrophysics has contributed enormously more to particle physics than ground-based experiments have.In the last 30 years? Since November 1974? Even if you discount the J/psi, do you really think that beauty, top, W, Z, and the tau neutrino are nil? It may be easy to be provocative. Perhaps it’s also easy to win a Nobel, like Veltman.

It’s easy to be provocative, as we know. If Veltman doesn’t think that astrophysics has contributed to particle physics, he must not care about the discovery of the muon, evidence for non-baryonic dark matter, dark energy, neutrino masses and mixings, constraints on everything from time-dependence of alpha to the mass of the photon, and just about all of general relativity. In the last thirty years, astrophysics has contributed enormously more to particle physics than ground-based experiments have.

Of course you still need colliders at the energy frontier, and it’s misleading (although not completely dishonest) to sell them through the connection to cosmology. Denying that there is a connection is just dishonest.

Lubos,

but of course I do care about the superpartners, if they exist, and/or the extra dimensions which would be even more shocking if they could be seen.So it would be shocking if superpartners were seen? OK, I might agree on that, but I’m surprised that you think that it would be shocking if you won your experimental-susy-at-the-LHC bet.

Of course a linear collider must be built. I don’t really care where, but it would be a disaster if this project were lost like the SSC, or apparently unable to produce any relevant information like Tevatron II. It is most likely the last big collider to be built in my lifetime.

Well I am on the outside looking in.:)

What value would Iscap be to the population of scientists then, and for that matter, subjects that would treat Bekenstein Bound, in relation to spin networks. You would have to throw John Baez in the bunch?

Would mathematicains then be left in abstract spaces not theoretically developing theIr math along side of the physics?

Of course that the linear collider would be built in order to learn the mind of God in the most scientific way possible. Do you think that these billions of dollars would be spent to learn the mind of Peter Woit? No! No one smaller than God is relevant in this game. ðŸ˜‰

Moreover, the linear collider has many advantages over the synchrotrons like the LHC. The latter is a hadronic machine, and the collisions are pretty dirty and most of the events are just pure QCD. Even if SUSY is seen, it may be pretty difficult to measure various parameters on the LHC.

On the other hand, the lepton machines are much better to measure the energy of all the particles in the game, and the date are sharper. It is hard to imagine that a useful new lepton machine could be built as LEP, and the natural step after the LHC is therefore a linear collider.

The linear collider would provide us with completementary information compared to the hadronic machines. I don’t care too much about dark matter – and I would agree with Veltman that the influence of astrophysics on theoretical high-energy physics has been small – but of course I do care about the superpartners, if they exist, and/or the extra dimensions which would be even more shocking if they could be seen.

I’m not so sure. The SSC was supposed to uncover the God particle, but it was cancelled anyway.

Physicist should just start sayin that their accelerators will “probe the mind of God” or somthin, they’ll get all the money they want from this gumint. I’m sure Lubos would be happy to testify before Congress.