/sci/ - Science & Math

Why is it that both moderation and users on this server promote such anti-string, anti-maths, anti-physics, crackpot demagogy?

>>5265222
There is quite a lot.

We have shown that string theory does not require any coupling constants - http://en.wikipedia.org/wiki/Dilaton

We have shown string theory resolves every single standard model anomaly, and all standard model field/particle content - http://en.wikipedia.org/wiki/Green%E2%80%93Schwarz_mechanism

We have shown that string theory naturally contains other extended objects, which can vibrate. The vibrations on these objects can be shown to be strings - http://en.wikipedia.org/wiki/D-brane, http://en.wikipedia.org/wiki/p-brane

We have shown that there are a finite number of moduli-stabilized solutions, all of which can be compactified on top of ordinary spacetime with the use of Calabi-Yau mainfolds. - http://en.wikipedia.org/wiki/Compactification_(physics)#Flux_compactification

We have shown that all of the string theories are equivalent to each other, and to the Kaluza Klein theory - http://en.wikipedia.org/wiki/T-duality

We have shown the AdS/CFT correspondence, which allows for easier calculations in the strong nuclear physics, investigation of black holes, and shows that string theory is entirely dual to ordinary gauge theory, with the added feature of a landscape of solutions - http://en.wikipedia.org/wiki/AdS/CFT_correspondence

There's much more to list, I'll continue in the morning.

>Woit
So many untrue statements from this one. He parasites on the work of scientists. Woit is a computer administrator and a lecturer in discipline, and is trying to revenge to the hep-th community for his inability to become a physicist himself.

You can check that during the last two decades, Peter Woit only wrote 3 rants against string theory and one unpublishable, 0-citation demonization of spinors in quantum field theory, earning less than 10 suspicious citations in total. For comparison, Edward Witten wrote nearly 200 articles during the same period, earning almost 40,000 citations from them. Peter Woit is not a scientist in any sense; he is just an activist.

You may also listen to an interview with Leonard Susskind (http://kqed02.streamguys.us/anon.kqed/radio/forum/2006/07/2006-07-31b-forum.mp3)), one of the leading physicists, who is also asked about Peter Woit and Lee Smolin and explains their grumpiness.

>>5265159
>>Feynman
>>crackpot
You are quoting the incoherent ramblings of an old, mentally-unstable man with cancer. But regardless, none of what he stated regarding string theory is true. String theory at the time of his criticism was lacking numerous things. It was not the qualitative framework it is today.

>Penrose
He considers inflation a fraud. He considers consciousness of a quantum mechanical origin. He considers the uncertainty principle erroneous. Need I say more? It's simply embarrassing for one of the most famous mathematical physicists to say - and believe - these stupid things about physics.

>Smolin
I have said this before and will say it again: every competent high-energy physicist who knows Lee Smolin may confirm that he is the ultimate symbol of the complete absence of the scientific integrity and, indeed, the very basic human ethical values.He does not understand what physics is. This fact is masked by popsci articles. If you do not believe me, please see http://online.kitp.ucsb.edu/online/resident/johnson2/rm/qt.html..

>>5264636
This is just exceptionally deceitful propaganda. String theory cannot “adjust” at all; it can't be modified, not even by an infinitesimal mutation. This will render the entire theory non-unitary, and thus it will contradict basic postulates of quantum mechanics and probability theory. You can freely deform standard model physics, or adjust some 20 or so continuous free parameters and extract observables after appropriate regularization/renormalization, but unlike standard model physics all of the solutions to string theory are exact, and also easier to calculate.

>>5264693
Too funny. Please inform me with all of your bulk popsci knowledge from uneducated journalists how this has any relevance to the “death” of string theory/supersymmetry. I cannot wait to hear the demagogic crackpottery. This is a deeply flawed and brutally misinterpreted proposition.

>>5264627
What you write is a complete haze of incoherent crackpot nonsense, and a typical mantra of brainwashed laymen.

> String theorists best argument to date is '...the only reason you don't like it is because you don't understand it'
If you cannot or refuse to understand ordinary standard model physics, you cannot attempt to understand string theory. You will have to suffice for a popsci description (A recent one which I have helped to create is located on http://whystringtheory.com/).). Sadly those who write such enlightenments are in “contradiction” with hundreds of uneducated, dishonest, anti-science subhuman crackpots who dislike the theory on an emotional basis.

>String theory disagrees with experiment, it's WRONG.
It most certainly does not. I am not even going to bother refuting anything just yet: first - do you have any evidence to support this claim?

>Unless of course you are a string theorist because then you could make another dimension
It is hysterical how this is always an argument. You must suffer from some kind of severe mental deviation or even retardation. Do you not realize standard model physics already contains 11 dimensions? The symmetry group U(1) x SU(2) x SU(3) x ISO(3,1) is exactly 11 dimensional. U(1) x SU(2) x SU(3) is compactified over a four dimensional manifold.

> that makes the experimental anomaly possible.
I’d love to hear what kind of “experimental anomaly” you are referring to. Any “experimental anomaly” contradicting string theory would destroy it. Your thoroughly irrational extrapolation is also incorrect. You do not “add” dimensions to string theory to resolve anomalies.

>>5264587
>operates at levels that are far too close to h to ever be able to carry out an experiment
You are just wrong. What you spew is pure pseudointellectualism. You are confusing string theory for some hypothetical quantum gravity theory absent of a landscape; you do not have any idea what string theory is or what it predicts. Please go read/learn actual physics as opposed to glancing through popular science articles.

>>5264572 They realize that it's just math, but it's still a valid field of inquiry.
String theory is not “just maths”. This is an entirely illogical and unjustifiable prejudice. String theory is falsifiable, recovers ordinary physics, and makes predictions. It is “science” in every facet.

So in phenomenology, in contrast to adjusting continuous parameters in a theory only valid effectively below the electroweak scale, we eliminate chunks of the landscape. With enough data from future colliders, and hopefully in our lifetimes, we will know precisely which vacuum we live in.

>and seems likely to remain so until the fad passes
You dismiss science due to its popularity? Do you have any idea what physics is? Your argument here is essentially meaningless babbling plus unsubstantiated bias.

> It amazes me how excited people are about bigger and more expensive accelerators and plasma facilities, and how little interest there is in the much cheaper, and more likely to be productive, research being done on the extremes of low energy, particularly ultracold neutrons.
More irrelevant babbling. Why do you compare entirely dissimilar branches of physics? This is comparable to dismissing research on evolutionary biology in place of field biology because it is somehow “easier” to research. If you do not like hep-th, feel free to work on something else, like your condensed matter. But keep in mind that many things in Nature are scale invariant - so just like quantum field theory, string theory will now find usage in your field with AdS/CM; it's still relevant to you.

From here we notice these objects already contain local supersymmetry (via reparametrization symmetry of the worldvolume), and quantize the theory with a GSO projection + BRST. The minimal extended object turns out to be a string propagating in 11 dimensions (via the cohomology of the generators of super translations), and we see from here that the various excitation modes of this object from such a coycyle are the particles - but this time there is magical cancellation of all standard model anomalies, divergences, and inconsistencies. And no need for any sort of renormalization, free parameters, or coupling constants. The theory naturally includes a graviton propagator and describes physics at all energy scales. There does not exist any other proposed “theory of everything” capable of doing this.

>It's notoriously lacking in predictive power, and seems likely to remain so until the fad passes.
That's just wrong. String theory is the only theory in the quantum gravity regime where we can recover unequivocal, qualitative predictions. To do calculations in the low-energy regime, we must obtain moduli-stabilized vacua with their corresponding superselection sector (full-blown theories of everything, each with their own cosmic evolution, symmetry breaking mechanisms, particles, interactions, and so on) which contain standard model particle and field content. It turns out that there are a discrete number of possible solutions, and so we see string theory is the only theory which tells us we will never have to probe the quantum gravity regime experimentally (which has been known to be impossible circa 1900s) to figure out what happens. We have a discrete number to provide to a single input parameter to specify the vacuum.

>>5264560 But lots of physicists do dismiss string theory.
No. Any “physicist” to dismiss string theory baselessly is a crackpot. Every repudiation that has been made against string theory thus far is absent of an argument.

>It's a quantum theory of gravitation formulated without respect to observations
This is just indecorous. String theory is “with respect” to every observation ever made. The Horn-Scmid duality demonstrates stringy behavior already present at the electroweak scale. The landscape has been shown in the 1990s to contain the standard model. The Maldacena duality implies string theory is equivalent to ordinary gauge theory.

To recover electromagnetism, you’ll notice the global U(1) symmetry, a group of automorphisms that acts on the local net of observables of the fermionic field, and promote this to a local (principal bundle over configuration space) symmetry. A similar process occurs with chromodynamics, with the gauge group SU(3). To recover string theory, you promote the gauge symmetries to U(N), SU(N), etc. where N tends to infinity. We know that this will transpire at high energies. The worldline Feynman diagrams which pronounce the processes of these symmetries can now be split into groups according to the topology of the corresponding extended objects (worldvolumes) that they discretize. This “large-N limit” is entirely equivalent to strictly continuous worldvolumes replacing Feynman diagrams.

>>5264494
>>implying that plenty of highly respected physicists aren't also dismissing string theory as an unscientific dead end
Name one.

This journalist is wrong. A spin-0 scalar is the most "natural" choice. It was to be expected, yes, but it is interesting to see Nature prefer such a "natural" thing. There is also some new physics. A ~4 sigma multijet excess (http://kds.kek.jp/getFile.py/access?contribId=12&resId=0&materialId=slides&confId=10806
) which favors some supersymmetry models.

But regardless the LHC is a great machine that works very well and pushes many frontiers but it's not a "miracle machine" that may answer all open questions about physics, at least not within two years. It has killed the composite higgs, preons, technicolor, portions of the SUSY parameter space, etc. This is a lot in a very short time.

>>5165518
Sorry, I was busy with a few things.

I do not see how it is vague at all. They defined <span class="math">\Gamma=\rho(\gamma)[/spoiler], so rewrite the Gamma and sympletic form as such with the new variables as differential forms. After you see that <span class="math">\partial_t\gamma[/spoiler] can be rewritten in terms of the symplectic vector field as <span class="math">X(\gamma)[/spoiler] (because <span class="math">\mathcal{L}\omega[/spoiler] is preserved on <span class="math">M[/spoiler]), you just use the identity given, <span class="math">\frac{d\rho}{dt}=X\circ\rho[/spoiler] in the integral. This is trivial, and comes from the fact that the flow generated by a symplectic vector field is an auto-symplectomorphism - http://en.wikipedia.org/wiki/Moment_map#Formal_definition

This is a trivial exercise. Do you need me to TeX the integral up for you? How old are you?

I am not sure what you mean by "geometries of manifolds". I have studied symplectic geometry, yes. I am a string theorist.

>>5165485
And how would A be incorrect?

>>5165389
a) Since it's on a bounded interval, use the fact that the <span class="math">\partial_t \gamma[/spoiler] can be rewritten in terms of the symplectic vector field, then the integral is just an identity with the moment map on <span class="math">M[/spoiler]
b) Assume that the Lie derivative of <span class="math">\phi[/spoiler] annihilates the symplectic form. Use Cartan's magic formula. Spoiler: it doesn't.

You aren't being funny, btw

What kind of maths do you know? If all you have is basic vector analysis, calculus, etc there is not a "more fundamental" explanation to provide.

Every physical system is able to realize the value of any projector that can be inserted into its consistent histories. Qualia are then the projection operators which act on the action of the Poincare group, the action being the GNS construction of a C*-algebra attached to every point on a statistical manifold having symplectic structure of CP(n).

Measurements are expressed as sets of projectors onto the eigenvectors of an observable. There is no "measurement problem", and there hasn't been one since the Copenhagen school made their (phenomenologically successful) assumptions about how macroscopic objects come about from microscopic laws.

What is there *conceptually* to discuss?

>>5158346 fundamental, beautiful
Except you forgot to leave out the part that Clifford algebras are a bunch of crackpot nonsense, and people who irrationally worship and generalize this algebra with a religious fervor fail at trivial high school maths. The relevant maths behind Lorentzian manifolds involves representations of isometries as Lie groups and Lie algebras, not new kinds of algebras.

Clifford algebras are reserved for algebras of matrices that have explicit Grassmann-even entries. Making isomorphisms to other structures and dogmatically referring to Clifford algebras as "fundamental" is a bunch of meaningless unsubstantiated masturbatory anti-mathematical gibberish. Also, the real maths is much more "beautiful" and still only one equation,
<div class="math">\int_{M} F\wedge\star F + F \smile j</div>
When mathematicians or physicists, and I mean real mathematicians or physicists, not deluded crackpots, talk about mathematical constructions such as spinors, the fundamental terms are groups, Lie groups, Lie algebras, and their representations. For fields, one also adds bundles, fibers, and so on. But Clifford algebras are at most a name given by one particular anticommutator that appears once when we learn about spinors, etc. and it never appears again. It does not represent spinors, vectors, or fields, and it does not bring a huge branch of new kinds of maths. It is simply one name for one equation among millions of equations. It is not being manipulated with in numerous ways like we manipulate complex numbers or Lie algebras - and it is certainly not "fundamental" in any sense, the spin group is.

>>5155197
The answer is derived exactly from your understanding. When you Fourier transform a massless propagator, you will recover the 1/r^2 law. A laymen interpretation of this comes from the measure of "virtuality" - i.e., how far off the mass shell the particle is, <span class="math">E^2-p^2-m^2[/spoiler]. The farther off, the less time the particle is allowed to exist by the uncertainty principle. Because photons are massless thanks to gauge invariance - the uncertainty principle allows the momentum to continually decrease - and the longer the particle is allowed to live.

Note that forces which use massful particles in their exchange interactions, such as the pions of the strong force, or the W/Z bosons of the weak, do not have this infinite range.

>>5155143
In that case - yes. There are no "virtual particle states" in the Hilbert space. The Hilbert space only contains real particles. Virtual particles don't correspond to any physical states, and there are no off-shell physical states in the Hilbert space.

That doesn't mean they do not have measurable consequences, for example all electrons in an atom receive energy shifts from virtual particles that act as quantum corrections. Even something as simple as determining the strength of an electric field is also indirectly "measuring virtual particles".

Your question is complete nonsense.

What do you mean by "interact"? There is surely an interaction term, the cup product of <span class="math">A_{\mu}[/spoiler] with the matter field, in any standard model Yang-Mills lagrangian - and they surely transfer momentum, else forces would not exist.

Virtual particles are objects that appear in in amplitudes for various processes - in the Feynman diagrams. They are the internal lines of these diagrams, given by propagators that determine the 2-point function (correlator) of a quantum field. They are a subset of momentum space, they simply do not follow the on-shell condition <span class="math">E^2-p^2=m^2[/spoiler]. In standard model physics, they can be either the quanta of connections on bundles, or sections of spinor bundles.