The article I’ll be talking about today is this one by Ethan Siegel called “Why String Theory is not a Scientific Theory”. Here’s the link:
Long story short: the astrophysicist/author in the above article needs to read some Thomas Kuhn and his book the Structure of Scientific Revolutions. What do I mean by this?
A Ph.D in astrophysics does not give one instant credibility to talk about a theory that is essentially about the subatomic world. Pardon my layman’s knowledge, but isn’t the study of the macro-scales of the cosmos different than studying the microscopic? Dealing with quantum physics all day and the mathematics of quantum physics is categorically different than studying stars.
With the immense proliferation of stuff claiming to be knowledge out there now, self-proclaimed experts, even Ph.D’s who then claim to know about every other subject are rampant. This goes in my mind for something even as close as astrophysics and quantum physics. I have no doubt that the author of the article here has a vastly superior knowledge of physics. That being said, his dive into philosophy, indeed ANY physicist’s dive into philosophy about how science is done, how revolutions in science occur, are fraught with problems.
First I’ll quote an article on the same subject by Tom Hartsfield that basically gives the same argument as Siegel, but uses the language of philosophy to justify its claim:
“String theorists met jointly with academic philosophers at a conference last month to talk about what we require of a theory for it to be held as correct. Do we need to test it experimentally? Or, are the qualities of beauty, consistency, mathematical interest, and greater funding proof enough?
It is a debate on which of two philosophies science ought to follow: empiricism or rationalism. The choice, to this physicist, is stingingly clear.
Science has been for its entire history fantastically successful precisely because it requires experimental tests to verify and confirm its claims. That criterion can be defined simply: empiricism. Ideas are not true simply because of their logic or conceptual beauty but because they are observed by human senses — or the extension thereof by cameras, telescopes, spectroscopes, thermometers, and so forth — and verified. Empiricism is not necessarily the best system of philosophy for all endeavors. Moral human beings accept many ideas and laws that are not learned from observation but instead found within (or without) and supported by the heart.
A different type of philosophical system describes the new guidelines that string theorists lust for: rationalism.
Rationalism derives truth via the process of deductive logic. Rationalism is the system of the mathematician. Theorems are logically correct because they can be built logically from a dictionary of axioms followed by deductions.”
This conference greatly interests me, because apparently no Kuhnians were there. I’ll explain what I mean later. It is interesting that Hartsfield frames the debate around string theory as a debate between rationalism and empiricism.
So some background. String theory is a theory which purports to reconcile quantum mechanics with general relativity into a unified theory. It is a complex set of mathematical axioms which describe elementary particles as consisting of vibrating open or closed strings. String theory also predicts the existence of multiple new dimensions in space, because for the math to work, it requires these extra dimensions.
So essentially the argument from Siegel is basically that because string theory has predictions that are not testable by current instruments, it is not justifiably called a scientific theory.
Now I’m on my guard for pseudo-science as well, and its interesting how Siegel uses Ted-talks to back up the claim that string theory is essentially just a branch of mathematics. I’m also willing to say that string theory should just be called the superstrings hypothesis or something- now we are getting technical about what a theory is.
However his and Hartsfield’s essential argument about how science proceeds has been debunked a long time ago. Science does not proceed in a calm fashion of simply waiting for the better theory to come along and plug the holes of the first theory. Thomas Kuhn argued that there is a necessarily cultural, and therefore conceptual dimension, to science. They always use Kepler’s theory as an example in this narrative as well.
So the idea is that science can only proceed through observation, but its funny how Hartsfield and Siegel use Einstein as an example. Siegel’s justification is that Einstein’s theory could be tested and verified- however Siegel admits that string theory can also be verified, but its not possible with our current technology. My answer to that is- so what? It still makes predictions doesn’t it? But his caricature of how science actually proceeds is laughable. The idea that Einstein did no mathematical “pure reasoning” is absolutely absurd. Everyone knows Einstein was first and foremost a mathematician, and some of the proofs of general relativity could only be tested very recently.
Hartsfield strawmans rationalism as only caring about the beauty of an idea, instead of its internal consistency. If a mathematical theory is internally consistent, that actually means something and pushes mathematics forward. I have heard mathematicians talk about how even if string theory isn’t correct, its still pushing the envelope of theoretical mathematics (and the mathematics of how objects act in 6-10 dimensions) forward. So the idea that there are no concepts or ideas involved in science, that it is pure observation, has always been one of the guiding myths of science- in fact its one thing that gives science, or rather physics, its legitimacy.
The point the author was trying to make about Kepler and Newton is that it doesn’t matter how simple or beautiful a theory is, if it doesn’t correspond to reality its not true. This is so self-evident that it makes me laugh. But the idea that string theory is inherently non-falsifiable may actually be true- but again, one of the biggest quandaries in philosophy is that if something is non-falsifiable, that doesn’t make it untrue. It may mean, as the author claims, that its a weak theory, but to me the author doesn’t engage with any of the theory surrounding string theory.
What’s my point? Ideas matter. If we can extrapolate from current models, models that are empirical, like quantum theory, then maybe we can make predictions about certain things. In this sense, I’m not arguing for rationalism against empiricism (whatever that means)- I’m arguing for arguing the merits of a scientific theory on the basis of science alone. What’s funny is that the author, in claiming to do that, is actually doing the exact opposite in my mind.
Does this mean I’m a proponent of string theory? I can safely say I don’t have the theoretical physics background to make a claim one way or another. All I can say is that based on the fact that string theory isn’t provable by current instruments (by a longshot- it would take energy 1 trillion times our largest particle accelerators to prove string theory definitively correct, which might be pretty dangerous) perhaps theoretical physics (emphasis on theoretical) has hit a threshold where people are realizing that the line between philosophical speculation and mathematics, the line between science and philosophy, cosmology and cosmogony, has started to blur. I’m willing to give proponents of string theory the claim that they are doing actual work, trying to work within the mathematics of the Standard Model of Particle physics for example, but it is interesting that the territory that was once occupied solely by philosophy is now being usurped by science, and science is at a loss to prove its claims. The territory of the “big questions”- what is the universe made of? When did it begin? We have more answers to these questions for sure! But even more questions. The only big question is, as I have stated in my other posts about physics- have physicists hit a theoretical dead end? String theory, as well as some other TOE’s (theories of everything), represent in my mind not only science’s highest hopes for a complete totalizing knowledge about the world, but also its possible epistemological limits.
For an epistemological pragmatist, the question becomes- can we just practically assume the universe is made of strings? Will that make everything else work? And furthermore- if it is, what are the consequences of that theory, for my life?
To me, string theory does have one piece of elegance that I really like as a theory about the world and matter- it theorizes that all particles are not just strings, but vibrating string-like patterns of energy. This already agrees with modern physics (E=mc^2 anyone?) If one thing is for sure, physics has proved that stable self-contained concepts like matter and energy are not only convertible, but actually one in the same thing. Any theory about the world must take into account this basically inviolable philosophical law- that the universe is one inseparable whole, what some philosophers might call the One-All, in that the multiplicity is contained within the fundamental unity. The problem for the physicist then is explaining this multiplicity