“It [String Theory] has attracted many, but no solutions have been proposed that have been found satisfactory or generally acceptable. It is here, it is claimed, that the presence of many solutions of string theory rides to the rescue. The string theory landscape, it is said, can explain why the cosmological constant is small – and the explanation is the anthropic principle. The anthropic principle is essentially the statement that the answer to some questions is conditioned by the fact that we are here to ask them. If I may ask the density of atoms around me is so vastly greater than almost anywhere else in the universe, a reasonable response is the fact that life cannot exist in empty space.”



In “What is String Theory?” by Joseph Conlon



“There is no direct experimental evidence for string theory.”



In “What is String Theory?” by Joseph Conlon



“Another example concerns Newton’s development of calculus.” (*)



In “What is String Theory?” by Joseph Conlon





I believe the path to learning String Theory could work like this, if memory serves (Kaku’s book explores this approach). Part 1: the least action principle, Noether theorem, group theory for dummies, K-G equation, Dirac, quantization of Maxwell, and intro QED; Part 2: path integrals, other covariant methods, renormalization, and intro QCD; Part 3: application of statistical mechanics to QFT, solitons monopole instantons (killer chapter), SUSY, and strings. Whew Ready? Go!

I fully accept that there are things we can never test and never verify. Heck, those things are fun and interesting to speculate on. I'm not even saying there aren't strings or that the idea is flawed. It would be fine if it were only claiming to be a maths exercise, but it's claiming to be science. As science it's a fine thing speculating on what is beyond our current grasp.

But, unverifiable speculation on those things does not make them theories no matter how cool and awesome they would be if it turned out they were true. String Theory explains nothing, it surmises that if there are stings it would explain some things and IF there are stings this must be how it would work mathematically. Just because someone creates a self consistent mathematical model that explains infinite turtles does impart an obligation for Turtle Theory to be correct, nor to shield it from demands for evidence no matter if the maths work out so the the turtles are in another dimension so they can't actually be disproved. I mean Turtle Theory explains even if does not predict so if you can get the math to work....

Some day perhaps there will be technology or a better understanding of the cosmos which will allow for evidence of strings, just as we grew and could test aether theory.

Think of it like the difference between an anthropological theory and a language theory. Both have implications for our understanding of history, and a language theory could potentially help to unify a larger group of theories. But there are some things about dead languages we cannot test or verify, such as pronunciation, dialect, precise meaning behind abstract words. But we can use some things we already know from anthropogy to show that the language theory must be correct, such as know that a certain word is an abstractualized version of a skilled trade word, and conveys something much deeper than a simple word.

String Theory fails to make explicit predictions of experiments. Its predictions cannot be tested, because there are none. Until string theory comes up with testable predictions, it remains Mathematics and not Physics. We must beware of beauty as a guide to truth. Sometimes it may be; other times not. A beautiful woman is not necessarily a good choice for a wife. We must also beware of excessive love of symmetry. Sometimes a symmetry may be true, other times false. The false symmetry between charge (electric field) and pole (magnetic field) in Maxwell's equations has led to failed predictions of magnetic monopoles. When looked at from a relativistic perspective, the symmetry between electricity and magnetism dissolves.

There is growing evidence that the symmetry between matter and anti-matter may be false: only approximate. Also, there is growing evidence that the time symmetry in the Schrodinger equation may be false, as it fails to take into account decoherence.

This theory is hanging by a thread. By a string actually... What about fabric theory, surely it’s stronger than string theories since its use more than one string…

All physics is "unproven" in that we don't prove things in science. What we try to do is to produce the best possible explanations. As for "dark matter, dark energy". Some say we have a good theory that accurately explains multiple phenomena, but has some anomalies which it does not explain. At this point one has to choose, does one assume that the theory is correct but our ontology is wrong, or does one assume that the ontology is correct and hence the theory is wrong? Professor Michio Kaku describes this interpretation of 'a good theory' as the ugliest ever proposed by humanity. It has no less than 19 mathematical fudges, does not reconcile relativity or quantum mechanics, and still has no suitable explanation for gravity. It's a terrible theory, responsible for side-tracking humanity from the true nature of reality, forcing us into a materialistic paradigm responsible in itself for so much destruction. Of course, Kaku believes in idealism (I don’t). Idealism allows Schrodinger's cat to be both alive and dead. While the cat's paradoxical existence is merely that of a thought experiment, the thought experiment itself is no less valuable than EPR was to opening up the door to our understanding of entanglement. I should also point out the fact that we can't definitively falsify anything. That's not to say that falsification isn't the right approach, clearly it has huge merits - and it's a lot easier and more reliable to falsify than prove. Feynman is right, of course, for those reasons. But he knew, even Popper realised, there's no such thing as definitive falsification.

I think when the scientists figure out what space is, figuring out what gravity is will be the next step, but trying to figure out what gravity is when nobody yet knows what space is seems to be putting the proverbial horse before the cart to me.

A final note: Maldacena’s AdS/CFT correspondence doesn't describe our universe. It’s got lots of problems I won’t delve into here.



NB1 (*). This statement should be read as “Another example concerns Leibniz’s and Newton’s development of calculus.” I must deduct another star on account of this glaring mistake.

NB: 3 stars for Conlon’s attempt at explaining internal symmetry (gauge symmetry) and giving us the history of String Theory in all its different flavours. ( )

Very well done!

Joseph Conlon is remarkably successful at communicating with intelligent non-experts. This book doesn't pretend to be a technical work on string theory, neither does it try to be a pop science book. The former, even at an introductory level, would demand a far greater commitment from the reader than many of us are able to give; for various reasons, the latter category has turned out to be a big disappointment to people like me. Conlon carefully gives just the right amount of detail to support, but not distract from, his thesis, which is (roughly) that string theory's position within physics has been rightfully earned. ( )

One of Conlon's 14 chapters is entitled "Direct Experimental Evidence for String Theory" and consists of a single sentence saying there is no such evidence! Yet Conlon is a string theorist himself, and the book authoritatively defends string theory's prominent existence -- not so much as a specific all-encompassing physical theory, but as a conceptual framework and a source of calculational tools such as the AdS/CFT correspondence. The volume thus joins, albeit in a different way, philosopher Dawid's 2013 book as one not to the liking of string theory's detractors.