And make no doubts about it, the "shut up and calculate" people are unambiguously the right ones.
Arkani-Hamed defended "shut up and calculate" – David Mermin's dictum usually misattributed to Feynman that was originally meant to sound pejorative – as the required pragmatic attitude that is needed locally in research for it to be scientific and not philosophical; however, a broader philosophical vision is needed, too.
He wants to have
the greatest respect for, such questions, coupled with a desire to find concrete paths to attacking them, rather than gaping at them in perpetual awe.Arkani-Hamed discussed examples of the "shut up and calculate" that were important when Albert Einstein was searching for the general theory of relativity in the darkness of confusion. Einstein needed to understand certain mathematical facts properly and once he did, things became straightforward.
(I haven't attended or watched his talk. Aside from years of interactions with the speaker, what I needed to determine the content of Arkani-Hamed's talk was to "shut up and calculate" LOL.)
In fact, he said an insight that I've been saying for a very long time, maybe even in discussions with him: A theoretical physicist may afford to be "somewhat sloppy" and his research may be "less than straightforward" because once certain totally qualitative conceptual ideas are correctly identified, what remains to be investigated is basically a finite number of possibilities how the concepts can be combined into propositions and arguments in a "spiritually correct" way. And after some time, pieces simply fit together and one arrives at the complete, technically correct, detailed theory or argument. Well, in this sense, the rough philosophical ideas are more central and valuable; the detailed technical work may be reduced to some combinatoric labor that sufficiently intelligent graduate students or collaborators (or you) may go through.
Well, sometimes it takes less time and sometimes it takes more time to migrate from the rough sketch to the final product. I still remember some three weeks in early 2003 when Andy Neitzke and I were completing a calculation of asymptotical, highly-damped quasinormal frequencies of black holes using a monodromy argument. We knew the result which was already calculated by another method and supported by very strong numerical evidence; we knew that "some monodromy properties" of Bessel's functions were relevant, and they should be combined to a constraint that implies the right values of the frequencies. But it took three weeks to combine the pieces correctly so that it worked. Partly because of our frequent communication, we arrived at the "Heureka" moment almost simultaneously.
One may say that this was pure mathematics because the problem was well-defined. But many problems in physics may be conceptually harder and more fuzzy. I would argue that the string theory's sketch of a theory of everything has been available since the mid 1980s and string theorists have already been oscillating in the right "basin of attraction" for more than 30 years, and finding new interesting local minima and structures over there. But the mapping of the basin hasn't been quite completed yet.
I only gave 2.7 cheers for "shut up and calculate" while Arkani-Hamed gave 3. Well, I don't want to overwhelm you with technicalities but he actually gave \(\pi\) cheers to "shut up and calculate" while I gave \(e\) cheers. Where does the difference come from? Well, my thinking is still a little bit closer to that of a seer. ;-) You know, I actually find the deep questions very important. And in some sense, I view all the precise calculations and technical work to be primarily some pile of dirty work whose real purpose is to strengthen some far-reaching philosophical principles. Well, the calculations are needed not just to support the hot conceptual ideas. They're often needed to make them well-defined, too. The rough recipe or a theory – like the "sum over histories of interacting quantum fields" – may look attractive but you're not guaranteed whether it may be translated to actual numbers that compute meaningful predictions in particular situations. Indeed, you may find out that it's possible but only sometimes and new conditions and required procedures (e.g. renormalization) are needed which couldn't have been guessed if you always stood at the level of words.
If you have a theory, like quantum mechanics, you may learn what the theory predicts for certain observables in some situations. When the verbal definitions and algorithms sound well-defined enough and if you can really extract the right predictions in a sufficiently diverse set of examples, it means that you have almost certainly found the well-defined rules and it doesn't make too much sense to spend too much more time on words. If you can predict all the things in a huge class of problems even quantitatively or numerically, and if you still realize that and why these examples follow from the same recipe or the same theory, it means that you probably understand the situation better than just at the level of some philosophers' words.
I believe that Arkani-Hamed's point that "shut up and calculate" is forced upon us equivalent to this simple point – that the deeper we understand physics, the more clearly we see that the human language is inadequate and the only correct litmus test to decide whether we understand something is that "we know how to solve numerous problems".
The philosophically inclined people – the enemies of the "shut up and calculate" principle – seem to misunderstand this very basic point, namely the point that mathematics is more accurate than just the words. In the case of the "interpretations" of quantum mechanics, they implicitly assume that the mathematics of quantum mechanics has been identified correctly or almost correctly but what remains is some huge pile of extra words that should be added on top of the quantitative rules of quantum mechanics in order to "clarify" these quantitative rules.
But that's completely upside down. Mathematics is what clarifies vague philosophical words. Mathematical formulations of the laws are the clarification of the more vague ideas that existed before the theory became quantitative! If quantum mechanics tells you what is the input for the quantum mechanical calculations, how it's determined (by observations), whether these observations are well-defined objectively or need the decision of a conscious observer (the latter), what can be calculated (probabilities of future observations), and how these predictions are calculated (through the mathematics of unitary and Hermitian operators on a complex Hilbert space), then it tells you the maximum. This description is clearly superior in comparison what philosophers ever had or could have. Trying to increase the "verbosity" of the story makes the story less well-defined and less exact, not more so!
Again, I actually like the deep questions and some of my "shock and awe" is basically permanent. The quantum revolution has been the deepest transformation of the 20th century science – and analogously, its understanding could have been the deepest change of my thinking about the physical world. This change has long-term or permanent consequences. However, what's important is that it's not just the questions we are excited by. It's also – and perhaps primarily – the answers that physics has brought us.
What I (LM) find so annoying about the "interpreters" of quantum mechanics isn't that they're asking far-reaching questions. Far-reaching questions are great and important. What I find annoying is that
they ignore the answers. They seem to ask questions because they're pseudo-intellectual posers, not truly curious people. And when you look closely, these questions aren't true pure questions. They're demagogic tricks to promote old, wrong answers – and ignore any new, correct answers or the search for such new, correct answers! These are my, Motl's words – I added this sentence because I was told that some people misunderstood it.So almost all the "interpreters" of quantum mechanics are asking deep questions that are actually recipes to think incorrectly. They implicitly and sometimes explicitly assume wrong things about Nature. When you ask "What is the precise objective, observer-independent state of affairs that exists in the real world at some moment," it's a question that deceives the recipient and wants him to think that there is some observer-independent information about Nature. But a key point of the quantum revolution is that it isn't the case. The knowledge of the state of the world must always be determined relatively to an observer and from his observations.
The idea that the laws of physics could depend on the observer could look like a contradiction to some people who would be told about it before 1925 – simply because they were used to the framework of classical physics and could have thought that it was there to stay forever. And it looked (and still looks) strange to lots of people who were recently told about it. But when one analyzes these matters properly, he must conclude that there is absolutely nothing illogical or logically incomplete about these laws of physics whose application depends on the observations. Most of the "interpreters" just don't want to learn these key answers – which is why their questions are actually just demagogic tricks to mentally keep themselves and their listeners in the 19th century while spending their careers by fooling people into thinking that the 19th century framework is more correct than the 20th century framework.
Also, what I don't share is Nima's optimistic picture of the future of pure theorists:
I will also argue that the "Shut Up And Calculate" philosophy is certain to grow in influence over time, as we draw ever closer to uncovering laws of physics governing the most fundamental elements of reality.Do I agree with that? It depends on how you measure the "influence". If one were always capable of picking the "actual best" theoretical physicists at every moment, including in the year 2100, the statement above would be correct, I think. As the foundations of theoretical physics will be getting even more abstract, mathematical, or impersonal, the "shut up and calculate" philosophy will be more influential on the reasoning of these top people. This process is clearly ongoing in quantum gravity and other corners of cutting-edge theoretical physics.
But what's the algorithm to pick these top people in 2100? And will they exist at all? I surely believe that there exist some "basically objective" ways to decide which people are at the top – or bottom of the depths – of the theoretical physics reasoning. But all such claims are disputed. Can we discuss the "influence" at all? And are we sure that someone in 2100 will be doing deeper physics than e.g. Nima today? Won't the society turn off this deep layer of itself completely?
So I prefer to use a WYSIWYG definition of "influence". I think that people who are absolutely deluded and absolutely contradict the "shut up and calculate" paradigm are immensely influential in the sense that is "measurable by surveys and social sciences" and their influence seems to be growing further. You may search for "quantum mechanics (an embarrassment)" on YouTube. The first video you get has over 600,000 views. Nima is arguably the most charming and energetic among the men who have won the $3 million Milner Prize, the most generous award for theoretical physics that the world knows these days. Correct me if I overlooked something but I think he hasn't even gotten close to 600,000 in the number of views of his talks about the conceptual foundations of physics or science.
While I think that the influence of the "shut up and calculate" thinking and other things should increase with time, a sensibly sociologically measured influence of this kind is decreasing in time while the influence of demagogic philosophical babbling is increasing, perhaps skyrocketing. And those 600,000 viewers don't represent just the ignorant laymen. There are lots of PhDs and physics PhDs or at least self-confident science journalists, officials at science institutions, students, and kids who are just naturally curious about science but when they try to get one, they are served garbage.
The observations of the society that I can perform indicate that the people who are deep and who know what they're doing may be approaching extinction, a de facto eradication by fake scientists and the fads that are destructive for science that have teamed up with these fake scientists. A brilliant pro-science kid who is naturally driven to become a top theoretical physicist faces dozens of traps, misinformation, discouragement, and outright threats. How many of these brilliant kids can make it to the actual top these days? Some secret society – perhaps a new, science-optimized Templar Order – will have to be created to save the pure science (deep theoretical physics in particular) from extinction, from the cruel death prepared by the superficial thinkers and demagogues.
I believe that people like Nima who live a comfortable life in ivory towers may be seeing something else but the path of the brilliant and curious teenagers to the world class theoretical physics has become much worse than what it was just two decades ago and some nontrivial efforts may be needed to make sure that "real physicists of the Nima's kind" will exist in the year 2100 at all.