The following story is a typical example of the things that I viscerally dislike about the current Academia and one of the reasons why I am so looking forward to be gone. The story will show that a portion of the Academia is literally built on
- superficial people
- people who're not able to recognize that the behavior of others is just a matter of politeness
The person who will prove my point is Scott Aaronson but be sure that his example is far from an isolated anomaly. First, it is really not difficult to show that he doesn't have an infinitesimal remnant of scientific integrity. How is he deciding about the validity of particular statements in theoretical physics? Please don't read the text below if you just had your dinner.
- I have therefore reached a decision. From this day forward, my allegiances in the String Wars will be open for sale to the highest bidder. Like a cynical arms merchant, I will offer my computational-complexity and humor services to both sides, and publicly espouse the views of whichever side seems more interested in buying them at the moment. Fly me to an exotic enough location, put me up in a swank enough hotel, and the number of spacetime dimensions can be anything you want it to be: 4, 10, 11, or even 172.9+3πi. ... I might have opinions on these topics, but they’re nothing that a cushy job offer or a suitcase full of “reimbursements” couldn’t change. ... Until then, I shall answer to no quantum-gravity research program, but rather seek to profit from them all.
It is absolutely impossible for me to hide how intensely I despise people like Scott Aaronson because this fact must be easily detectable by looking at my skin color and other quantities and observables. ;-) He's the ultimate example of a complete moral breakdown of a scientist. It is astonishing that the situation became so bad that the people are not only corrupt and dishonest but they proudly announce this fact on their blogs.
In fact, I have learned that the situation is so bad that when I simply state that Aaronson's attitude is flagrantly incompatible with the ethical standards of a scholar as they have been understood for centuries, there could be some parts of the official establishment that would support him against me. There doesn't seem to be a single blog article besides mine that denounces Aaronson's attitude.
Corruption has become the holy standard and some fields completely depend on it. Feminist career scholars who belong to the diversity industry financially depend on their pseudoscience about the absence of differences between the sexes much like a large fraction of the climate scientists' funding depends on spreading unsubstantiated fears and much like the loop quantum gravity research depends on spreading myths about the existence of "alternatives" to string theory even though these "alternatives" are nothing else than artifacts of confused, superficial, and sloppy thinking. And some of these people will openly tell you that the reason why they say what they say is their financial well-being.
The Academia is simply contaminated beyond imagination. You can guess that Aaronson doesn't say anything nice about me either. The difference between two of us is like the difference between a superman from the action movies who fights for the universal justice on one side and the most dirty corrupt villain on the other side. It's like the Heaven and the Hell, freedom and feminism, careful evaluation of the climate and the alarmist hysteria, or string theory and loop quantum gravity. ;-)
In order to avoid misunderstandings, let me emphasize that Aaronson's comment is no joke. First of all, it is not too nice to be joking about these serious matters. But there is a simpler way to see why it's no joke. He has not only written what he wrote: has has also acted like that. He has advocated the crackpots and when he was paid a visit to California, he started to write different things. He's a corrupt piece of moral trash. My anger may be quiet but it is unyielding. It's not just him: the Academia is literally flooded by intellectual prostitutes.
Stanford and weird discussions
Scott Aaronson was invited to Stanford to speak about some alleged links between the anthropic principle and NP-complete problems in computer science. He mentioned some elementary - for him - things about computational complexity plus its hypothetical relations to the landscape. He referred to the paper by Douglas and Denef. I don't think that their paper holds too much water - they assume that the configuration space of string theory is an uncontrollable, chaotic pile of numbers, and they use this assumption to derive that the configuration space of string theory is an an uncontrollable, chaotic pile of numbers that can't be used to find the right place where we live. ;-)
From the viewpoint of conventional physics, this statement is kind of manifestly wrong. If we made the appropriate measurements of physics at various scales up to the Planck scale, especially at the compactification scale, we could simply *measure* various parameters of the compactification. We could *measure* the fluxes and the numbers of branes wrapped on various cycles and simply reconstruct what our compactification looks like: here I assume that we live in a standard flux compactification but similar procedures could work if we live in another kind of vacuum, too.
We could determine various currently unknown features of Nature just like the physicists typically did thousands of times in the past: using experiments. Even without experiments, we can find - and we are frequently finding - new theoretical organizing principles that increase our understanding of the theory. Every insight makes our picture of reality less confusing and more comprehensible while it makes the argument of Denef and Douglas weaker. Even if the task of finding the exact vacuum were difficult in practice, it is pretty obvious that the additional measurements would simplify our search for the correct vacuum.
Denef and Douglas have to assume that we won't find any new organizing principle which is a pretty pessimistic - and unlikely - assumption. What a surprise that they can derive pessimistic conclusions.
Fine. I don't want to argue about Denef and Douglas because these physicists are extremely smart and experienced and they know what they're doing and how the actual terms in various quantities such as vacuum energy look like. But now we discuss another piece of work which seems to have nothing to do with the vacuum selection problem: correct me if I am wrong. The author just argues that he did something in computer science because of his thinking about the vacuum selection problem but this opinion seems to be a consequence of his not knowing what the vacuum selection problem is actually all about.
Unconventional seminar speakers
You know, high-energy physics groups often invite speakers who are not exactly in the mainstream but who can be interesting or inspiring because of other reasons. The more pedantically these speakers focus on our field that they don't understand, the more nonsensical the resulting talk typically is.
Needless to say, when you're the organizer and when you're a hospitable person, it is obvious that you will try to make the visit as pleasant for the speaker as you can even if his talk makes no sense. This is how good organizers normally behave. After all, we don't want to create a hell out of our environment that couldn't be cured by turning the monitor off. Many of us have organized many kinds of seminars and we could share our stories. The string theorists are undoubtedly among the most hospitable people in the world.
But the speaker must be very silly if he misinterprets the hospitality and politeness as a confirmation of his ideas about the Universe. Be sure that virtually all well-known senior string theorists realize that all the comments about the "alternatives" of string theory are just mathematically unconvincing conglomerates of half-baked ideas that can often be easily disproved within a minute and that are considered to be worth a talk only because of the unusually poor standards of their proponents.
At the same moment, the string theory community contains a huge number of very generous and receptive hosts. These two features are not necessarily in contradiction with each other because they refer to different types of the string theorists' mind. The fact that a string theorist understands that loop quantum gravity is nonsense is about her familiarity with some general facts, arguments, and theorems about theoretical physics. The fact that she is a great host talks about her social qualities.
But one shouldn't forget that these are two very different characteristics that manifest themselves in different situations. They shouldn't be mixed with each other. And if there is a risk that there could be a misunderstanding, I think it is a good policy to try to avoid such a misunderstanding.
Local description of quantum gravity
Scott Aaronson refers to some comments of Steve Shenker and especially Lenny Susskind about the local description of gravity. Although it would be nice to have a local description of string theory, one that resembles the old-fashioned field theories as closely as possible, it seems clear to me that there exists a lot of unnecessary fog about this question.
First of all, we do have such a description in many situations. It is called string field theory. String field theory has its issues - especially its awkward treatment of closed strings that doesn't seem to tell us anything about non-perturbative physics. Nevertheless, it is a correct local off-shell description of perturbative string theory. There are indeed many "local fields" at weak coupling of string theory. If you suggest that there is another local off-shell description of weakly-coupled string theory, you're pretty close to a contradiction. If you choose different degrees of freedom than the elementary string fields, they will have to be strongly coupled in order to describe the same physics. No one - not even Lenny Susskind - has ever told me in what sense this description should be better than string field theory as we know it so I consider this line of reasoning to be pretty much closed.
At weak coupling, we know more or less everything we want to know about string theory: there could perhaps exist some interesting things we should know but we don't yet know what these future questions are. ;-) It would be really great to extend our tools - such as the worldsheet conformal field theory - to all values of the couplings. But the perturbative part of the resulting formalism is physically understood.
Manifest Hawking-Bekenstein entropy
Scott Aaronson says that the loop quantum gravity proponents agree with conventional quantum gravity - and string theory - that the black hole entropy is proportional to the horizon area. That's a very bizarre statement. The proportionality law was, first of all, found by Bekenstein who has made some visionary observations about the laws of thermodynamics and their links with physics of black holes and by Hawking who has quantitatively incorporated these visions into semiclassical quantum gravity.
Second of all, the entropy formula was independently derived in string theory for rather large classes of black holes. These derivations look completely different and inequivalent according to the present understanding of physics of string theory. It is likely that a more complete and universal description of string theory will make this conclusion seem less mysterious but right now, the confirmation is something that no reasonable physicist can dismiss because it is a highly non-trivial argument supporting the formula as well as the statement that string theory is the only known consistent theory of gravity.
And yes, it is probably also the only mathematically possible theory of quantum gravity but right now, we can't prove this assertion directly.
Loop quantum gravity cannot derive that the entropy is proportional to the area and it is likely that if loop quantum gravity is treated properly according to its rules, the proportionality law doesn't hold. The law only holds if we assume that all the degrees of freedom in the black hole interior can be ignored and should be ignored: the whole region must be removed from space by hand and a new kind of physics must be attached at the end-of-the-world domain wall. These degrees of freedom are ignored because we want to get a certain result. No one has any other justification of this step that would follow from loop quantum gravity itself. Moreover, the calculation of the proportionality coefficient leads to a completely wrong result instead of the correct factor of one quarter.
Some loop quantum gravity proponents can perhaps agree that the proportionality law is true - because the evidence supporting this law is overwhelming, exact, and based on many different and inequivalent formalisms. But it is dishonest to pretend that the proportionality law is equally close to the equations of loop quantum gravity as it is to string theory. The real situation is extremely far from being a symmetric one.
Universality of the area law
Another thing I want to say is the following: the proportionality law holds for all kinds of large black holes. It is a universal law. But the reason why the law is universal is explained by arguments based on general relativity itself: imagine something like Wald's derivation of the entropy or one of the procedures by Steve Carlip. I think it is a fundamentally flawed idea to expect another universal proof of the formula that is not based on general relativity.
After all, the usual general relativistic description is the only one that can easily talk about the "horizon area". If you have a different description that doesn't directly use the metric tensor as a degree of freedom, it won't provide us with any universal method to define the "horizon area".
The only thing that all these black holes in different vacua of string theory share is the horizon area and the Einstein-Hilbert action for some of the relevant low-energy degrees of freedom. There is nothing else that they share, and there can thus be no other universal derivation of the law. The people who believe otherwise are probably making the same mistake as the people who try to derive two inequivalent descriptions of a weakly-coupled regime of a physical theory.
The alternative, microscopic calculations of the black hole entropy look different. Most of them are eventually based on Cardy's formula but the exact identity of the CFT whose density of states is calculated by this asymptotic formula differs from one black hole to the next. The macroscopic classical description based on general relativity is the only thing that all black holes really share.