Hawking radiation is a very robust prediction. It comes simply from applying quantum field theory in the curved space-time near the event horizon. It's also part of the synthesis called "black hole thermodynamics", for which string theory provides an explanation in terms of the statistical mechanics of microstates. In the S-matrix of quantum gravity, if black holes didn't evaporate, they'd show up as asymptotic states, but they don't. (There are eternal black holes in anti de Sitter space, but they still evaporate, they just don't get to evaporate completely; the particles produced by the evaporation can't escape to infinity because of the peculiarities of AdS geometry, and fall in again.)

So denying the existence of Hawking radiation would screw up many other things. You could say that Hawking radiation is real but that it falls back in, like in AdS space, but there's no reason for it to do so. The paper featured at arxivblog is a "what if" paper which ignores all these problems and proceeds to calculate some of the consequences. You could compare it to an engineering study of one of M.C. Escher's impossible structures: if you ignore the contradictions in its design, maybe you can calculate some of its properties, but it only has recreational value to do so. We don't quite *know* that a nonevaporating quantum black hole is logically impossible, in the way that we know the impossible staircase is impossible, but in the future a genuine proof may be available.

But empirical confirmation of black hole evaporation is rather unlikely. If we could produce mini black holes in colliders, then we'd see it, but those models aren't especially favored; they are a "what if" of a different sort, one in which there is at least a consistent fundamental picture behind the hypothesis (particular braneworld models), but it's just one of many possibilities about what happens at the next frontier of physics and those models are not significantly favored. (These models are also the ones which predict a detectable signature in GRB data.) If we could send a probe to the edge of an astrophysical black hole, maybe the radiation could be detected, but that is a job for interstellar civilizations, if they exist.

Maybe you could find indirect evidence for Hawking evaporation of primordial black holes in the cosmic microwave background. But I don't know how likely that is - again, it would be highly model-dependent.

String theory includes every self-consistent conceivable quantum gravity situation, including 11 dimensional M-theory vacuum, and various compactifications with SUSY (and zero cosmological constant), and so on. It can't pick out the standard model uniquely, or uniquely predict the parameters of the standard model, anymore than Newtonian mechanics can predict the ratio of the orbit of Jupiter to that of Saturn. This doesn't make string theory a bad theory. Newtonian mechanics is still incredibly predictive for the solar system.

String theory is *maximally* predictive, it predicts as much as can be predicted, and *no more*. This *should* be enough to make severe testable predictions, even for experiments strictly at low energies--- because the theory has no adjustable parameters. Unless we are extremely unfortunate, and a bazillion standard model vacua exist, with the right dark-matter and cosmological constant, we should be able to discriminate between all the possibilities by just going through them conceptually until we find the right one, or rule them all out.

What "no adjustable parameters" means is that if you want to get the standard model out, you need to make a consistent geometrical or string-geometrical ansatz for how the universe looks at small distances, and then you get the standard model for certain geometries. If we could do extremely high energy experiments, like make Planckian black holes, we could explore this geometry directly, and then string theory would predict relations between the geometry and low-energy particle physics.

We can't explore the geometry directly, but we are lucky in that these geometries at short distances are not infinitely rich. They are tightly constrained, so you don't have infinite freedom. You can't stuff too much structure without making the size of the small dimensions wrong, you can't put arbitrary stuff, you are limited by constraints of forcing the low-energy stuff to be connected to high energy stuff.

Most phenomenological string work since the 1990s does not take any of these constraints into account, because they aren't present if you go to large extra dimensions.

You don't have infinitely many different vacua which are qualitatively like our universe, you only have a finite (very large) number, on the order of the number of sentences that fit on a napkin.

You can go through all the vacua, and find the one that fits our universe, or fail to find it. The vacua which are like our universe are not supersymmetric, and will not have any continuously adjustible parameters. You might say "it is hopeless to search through these possibilities", but consider that the number of possible solar systems is greater, and we only have data that is available from Earth.

There is no more way of predicting which compactification will come out of the big-bang than of predicting how a plate will smash (although you possibly can make statistics). But there are some constraints on how a plate smashes--- you can't get more pieces than the plate had originally: if you have a big piece, you have to have fewer small piece elsewhere. This procedure is most tightly constrained by the assumption of low-energy supersymmetry, which requires analytic manifolds of a type studied by mathematicians, the Calabi-Yaus, and so observation of low-energy SUSY would be a tremendous clue for the geometry.

Of course, the real world might not be supersymmetric until the quntum gravity scale, it might have a SUSY breaking which makes a non-SUSY low-energy spectrum. We know such vacua exist, but they generally have a big cosmological constant. But the example of SO(16) SO(16) heterotic strings shows that there are simple examples where you get a non-SUSY low energy vacuum without work.

If your intuition is from field theory, you think that you can just make up whatever you want. This is just not so in string theory. You can't make up anything without geoemtry, and you only have so much geometry to go around. The theory should be able to, from the qualitative structure of the standard model, plus the SUSY, plus say 2-decimal place data on 20 parameters (that's enough to discrimnate between 10^40 possibilities which are qualitatively identical to the SM), it should predict the rest of the decimal places with absolutely no adjustible anything. Further, finding the right vacuum will predict as much as can be predicted about every experiment you can perform.

This is the best we can do. The idea that we can predict the standard model uniquely was only suggested in string propaganda from the 1980s, which nobody in the field really took seriously, which claimed that the string vacuum will be unique and identical to ours. This was the 1980s fib that string theorists pushed, because they could tell people "We will predict the SM parameters". This is mostly true, but not by predicting them from scratch, but from the clues they give us to the microscopic geometry (which is certainly enough when the extra dimensions are small).

## Best Answer

There is a mathematically precise dictionary from perturbative string theory to perturbative quantum field theory obtained by systematically taking the point particle limit of string backgrounds encoded by 2d SCFTs via a "degeneration limit" that turns these into spectral triples.

I have written an exposition of this process, with pointers to the literature, at PhyiscsForums, here:

Spectral Standard Model and String Compactifications(Beware though that, while precise, there is much, much room to develop and explore the mathematical process further. )