The media and especially blogs continue to be literally overwhelmed by incredibly stupid proclamations of remarkably ill-informed people about theoretical physics.
Backreaction.blogspot.com keeps on promoting the blue crackpot book as an important work - mostly because its author is asking similar elementary undergraduate questions as Sabine does and is also desperately waiting for someone to tell him the wrong answers he wants to hear.
Posters at Asymptotia.com except for Clifford, Moshe, Mark, and an anonymous coward who happens to know every recent paper about particle phenomenology flood Clifford's blog with tons of pure garbage. Samantha whom we know as a fanatical feminist writes that she has just revolutionized science and superseded string theory but unfortunately she must go out for a bit so she can't discuss her ideas right now. ;-)
Carl Brannen writes a few wrong identities involving zeta functions and argues that this is why string theory is wrong. Peter Woit wants to look smart so he says that Carl Brannen is too stupid and he (P.W.) would erase his comment if it appeared on N.E.W. - only "intelligent" comments saying "it is not even wrong" are allowed there.
Clifford is repeatedly recommended to read crackpot books because it is apparently needed to discuss string theory. Well, it is only needed to discuss string theory with complete idiots such as the readers of N.E.W. Clifford is very nice to P.W. - the kind of "oh, Peter, you're so cute, do you need new diapers?" Believe me, you won't get rid of the aggressive and dishonest crackpot in this way, Clifford.
But let me get to the main source of silliness here.
An Edge Symposium was dedicated to Einstein but this giant is no longer a source of passions. That's why Brian Greene, Walter Isaacson, and Paul Steinhardt started to talk about string theory. Brian Greene says good things in a very polite way - you can see that Brian who is surely no warrior is being influenced or intimidated by the environment.
The main aggressor in the debate is Paul Steinhardt. While he offers some speculations that might be right - for example that Einstein would probably love string theory as another step in geometrization of physics - he also says so many breathtakingly dumb and bitter things about inflation and string theory that Not Even Woit would be ashamed of them. Saying that inflation is becoming a failure exactly during the decade when it begins to be confirmed experimentally is just way too much for the author of such a sentence to be taken seriously. Steinhardt may be trying to kill the Nobel prize for inflation that could otherwise be distributed in three weeks from now.
But his comments about inflation are nothing in comparison with the following assertion:
But what angers people is even the idea that you might accept that possibility — that the ultimate theory has this googol of possibilities for the laws of physics? That should not be accepted.Wow. Just the possibility angers them. ;-)
Many multiverse people have always emphasized the Copernican principle - that the Universe is big and we live at a random place. There are many other places and many other galaxies even though we can't observe their stars individually. These multiverse people were often presenting the current situation as analogous to the era when heliocentrism had to fight against the religious and Aristotelian prejudices.
Every serious participant of these discussions has always realized that this comparison doesn't prove anything - it is just a story that makes a certain scenario plausible. These stories should be counted as propaganda, not science. Those of us who think that the anthropic reasoning won't be crucial in the final picture prefer other analogies. But all of us realize that this question is not settled which is why different approaches must be allowed.
But I was always feeling doubtful not only about the science behind the analogy. I didn't believe the sociology either, especially the implicit message that some opponents of the anthropic reasoning would be using similar arguments as the Catholic Church was using in the 16th century. In fact, I used to think that even the old catholic opinions have been idealized and demonized so that the heroic struggle of science against religion looks more impressive.
Well, I was apparently wrong. What Steinhardt said now, in the 21st century, is completely identical to the idealized picture of religious fervor that was trying to kill the scientific revolution during its infancy. I am really amazed because Steinhardt's approach is so flagrantly incompatible with basic principles of the scientific method that Steinhardt, and not the Catholic Church, should be used as the ultimate bad example in textbooks for children.
Looking at Steinhardt's incredible statement
First of all, whether "people" are "angered" must be absolutely irrelevant for science as long it remains a science. All serious theoretical physicists surely think that, for example, all fans of Peter Woits are imbeciles and the fans' "anger" really can't change the scientific facts or opinions and shouldn't change them. If scientists were routinely intimidated by laymen's anger, they couldn't get too far. Our civilization has a lot of experience with what happens if the "anger" of masses is allowed to manipulate with opinions of individuals.
Surely, millions of simple-minded and brainwashed members of the Catholic Church were "angered" in the 16th century when they heard that the Earth - I mean the main celestial body that was created by no one else than God during the first day - was actually not in the center of the Cosmos. The Earth was the only body where people could have walked, they didn't feel that it was shaking, and the Universe looked identical in all directions. These and other facts, including the Bible, were surely proving that the Earth must be at the center and nothing else can ever be accepted, right? Indeed, it wasn't accepted and some heretics were executed.
It might be largely because of the predominantly atheist environment in which I was grown up but I have always considered such "anti-heretical" sentiments, indicating that someone is afraid to even think about a possibility, to be childish. People can believe wrong theories and most of them do - and it may be unpleasant if ill-informed people start to control your life (which usually happens if there are many of them around). But I simply can't understand how someone can feel threatened by a few people who work on their theories or how he can be scared of thinking about a possibility with his or her own brain.
Well, this is called bigotry. Those who can't accept that underlying equations have many solutions or that biology is surely behind some of the male-female cognitive differences are examples of it. They not only want to refuse these facts themselves but they also want to force the rest of the world - 100% if possible - to believe the same myths as they do. The taboos seem necessary for their life. They are dreaming about a "scientific consensus".
According to state-of-the-art theoretical physics, there are infinitely many stabilized backgrounds of quantum gravity that share basic features - such as the existence of gravity and the postulates of quantum mechanics - but whose physics differs in detail. I think that every good theoretical physicist knows that the previous sentence is most likely a fact. You don't need any fancy KKLT-like vacua: the AdS5 x S5 SU(N) backgrounds are enough to prove the main thesis. Whether a vacuum is a semi-realistic one is a matter of definition anyway: how much it has to be realistic to be called semi-realistic? The existence of many possible types of physics is not a new thing - there have been many quantum field theories, too.
What's new is that string theory is a complete theory so it unifies all these possibilities into one picture where all possible environments are connected in one way or another.
People disagree how they should interpret the wrong vacua, how cosmology makes or doesn't make some of them relevant, and how science should proceed. But the existence of many choices is simply not such a controversial result. It is a result of very solid calculations that can be checked in thousands of ways. It is not really possible to do theoretical physics correctly while denying this basic fact. Even if the fact were controversial, you can't ban it unless you want to join the worst tyrants in the history.
Paul Steinhardt pretends that he can rule out the very existence of many solutions:
I can't believe that he believes that these words are a proof that there are no other vacua. When the observational data are rationally evaluated, the correct conclusion is that we don't know how many other "pockets" the Universe has or how many stationary points the underlying equations admit. Saying that the observations imply that the answer is one is a result of a completely sloppy, unscientific thinking.
That [many solutions] should be regarded as an out and out failure requiring some saving idea. The fact is that, everywhere we look in the universe, we see only one set of laws. Also, the universe is smooth and uniform, smoother and more uniform than we need for humans to existence.
Every important development in science has made the world "larger" in some proper sense. Each of them has allowed us to predict (and see) some new objects or phenomena that were thought to be impossible. The Copernican revolution has increased our ideas about the size of the Cosmos. Later, billions of new galaxies outside the Milky Way were added to the picture.
Relativity predicted some "obviously impossible" phenomena that appear at high speeds. Quantum mechanics predicted hundreds of new "obviously impossible" phenomena at short distances. Dirac's equation has predicted antiparticles, the electroweak theory has predicted W and Z bosons and the Higgs, other field theories have predicted new particles and interactions at higher energies than what could be previously observed. Hawking has figured out that radiation can get out of black holes, after all, and so on and on and on.
Steinhardt's "argument" could have been used - and indeed, was often used - in every single case to stop the progress. I think that good contemporary physicists are much more able to properly evaluate what we know and what we don't know than their ancient predecessors. With relativity, we learned physics at arbitrarily high speeds but still didn't know what was happening at atomic distances. That was answered by quantum mechanics. You could continue. Today, we know how physics in the visible Universe works up to some distance scales or energy scales. Clearly, what happens at higher energies than those we have seen remains somewhat mysterious, much like physics outside the observable Universe if there is one.
An honest scientist must agree that we don't know certain things.
Saying that these limitations of our current theories don't exist is dumb. It is equally dumb to say that the general picture of the multiverse is incompatible with some basic observations. It is fully compatible. Steinhardt's hatred against the "googol" of Universes is nothing else than the well-known 16th century catholic bigotry against everything that questions the uniqueness of God and the special character of His creation. I thought that we have grown up a little bit during the last 500 years. Only some of us have.
Inflation - another thing that Steinhardt dislikes - explains why the visible Universe is so uniform, smooth, and flat. But it doesn't imply that there can't be anything else besides this smooth patch. The multiverse cosmologies are compatible with all basic features of the Universe that we observe.
String theory is a theory of everything
You can see how Brian is being intimidated into "retracting" that string theory is our only candidate for a complete theory of everything. They don't fully succeed but the pressure of ill-informed people, if I have to avoid the term idiots, is just becoming scary. Does someone really want to ban physicists from saying that a set of equations has XY solutions and it is the only set of equations with certain properties? Do all people with IQ above 140 have to become heretics because of some angered simpletons?
Is Leonard Susskind supposed to apologize for his heresy - his belief that the multiverse is the final picture? Should I be ashamed that I wrote a paper with him (more precisely he agreed to put the name there)? ;-) I am not ashamed at all!
By saying that string theory is a theory of everything, we mean something very particular, something that has been repeatedly explained even to the public, and something that is almost certainly true. And it is the following: if you assume that string theory is a correct next step in finding the rules that govern all elementary particles and their interactions, it is the final step. Why?
Simply because string theory, unlike all previous theories in physics, admits no continuous deformation and it has therefore no continuous adjustable parameters. It cannot be an approximation of a more accurate theory because the theory doesn't break down under any circumstances and every attempt to deform its rules turns out to be either a journey along its moduli space that already exists, or it turns out to be inconsistent.
Why? Perturbative string theory must be formulated in terms of a worldsheet conformal field theory, for consistency. The space of conformal field theories is by definition the same thing as the configuration space of massless scalars. Every conformal field theory that exists is a background of perturbative string theory and every theory that violates the rules is inconsistent as a background of perturbative string theory. The only other modulus is the dilaton that determines the strength of the stringy interactions. Similar arguments may be made in other descriptions that don't rely on the weak coupling.
Eventually, there are portions of the "landscape" with exactly flat directions - massless moduli - that are unlikely to be relevant for phenomenology because of their "fifth forces". And then there are portions of the landscape where the stationary points are discrete, isolated minima. By analyzing such a minimum properly, one can derive the spectrum of particles (and other objects) as well as the strength of all kinds of interactions in between them. These things directly or indirectly determine everything that happens in the real world which is why the theory is a theory of everything unless it is completely wrong which seems extremely unlikely.
And that's the memo.