String Theory, speculation or hypothesis

 

Scientists think about known phenomena and known data that puzzles them and try to think of ways to fit theory into the observations. They then come up with ideas, and make predictions of what else we should see if these ideas are correct. They then do experiments and make observations to see if the predictions of the idea are true, and if so they incorporate the idea into existing theory. This is usually called a "hypothesis." "Speculation," on the other hand, are ideas for which no experimentally testable predictions can be thought of, either because we don't have the needed technology or because it is too unpredictable ("woo") to be reliably experimented on. String theory, for example, is often labeled speculation for the reason that most of its predictions are effectively untestable: to test them would require technology we don't have. So, string theorists look for things string theory predicts that are testable. An example is if we can measure gravity wave polarization, this could test the reality of string theory. The thing that impresses me about string theory, as compared to a lot of speculation you see, is it is so consistent mathematically, the sort of thing sometimes called beauty or elegance. I know that is what keeps them working on it in spite of the criticism. Maybe that is enough to convert it from speculation to hypothesis. It seems to sit on the boundary.

You’ve drawn the line about as well as working scientists actually use it, though in practice it’s a bit fuzzier and more political than the textbook version.

A hypothesis, strictly speaking, isn’t just “an idea,” but an idea that earns its keep by exposing itself to possible failure. It says: if I’m right, you should observe X under conditions Y. The key is not that we can test it today, but that we can at least state clearly what would count as evidence for or against it.

Speculation begins where that breaks down—either because no such tests can be articulated even in principle, or because the connection between the idea and observable reality is too loose to pin down.

Where your example—string theory—gets interesting is that it lives in that uncomfortable middle ground.

On paper, string theory does make predictions. The trouble is that most of them sit at energy scales or conditions (Planck-scale physics, extra compactified dimensions, etc.) that are wildly out of experimental reach. So it’s not that it’s untestable in principle, but that it’s effectively untestable for the foreseeable future. That’s why many physicists are reluctant to grant it full “hypothesis” status in the same way as, say, the Higgs mechanism was before it was confirmed.

Your point about mathematical elegance is exactly right, and it has a long pedigree. Theories like Maxwell’s equations or General Relativity were admired for their internal coherence and beauty before all their consequences were experimentally confirmed. In those cases, elegance turned out to be a good guide.

But—and this is the cautionary part—history also contains beautiful theories that went nowhere. Mathematical consistency is a necessary condition for a physical theory, but not a sufficient one. Nature is under no obligation to be elegant in the way we find aesthetically pleasing.

So what keeps string theory alive is really three things:

First, it’s not just elegant—it’s unusually constrained. Once you assume certain starting points (quantum mechanics + relativity + extended objects), the mathematics doesn’t give you a lot of wiggle room. That gives physicists the sense they may be uncovering something deep rather than inventing freely.

Second, it has had “spillover success.” Techniques developed in string theory have illuminated problems in other areas—black hole entropy, quantum field theory, even some condensed matter systems. That gives it indirect credibility.

Third, there’s still hope for indirect tests—like the gravitational wave polarization idea you mentioned, or cosmological signatures. These are long shots, but they keep it from slipping fully into the “woo” category.

So I’d phrase it this way:

String theory isn’t pure speculation, because it does connect to known physics and, in principle, to observation. But it isn’t a well-formed empirical hypothesis either, because it hasn’t yet produced clear, testable predictions within reach.

It’s something like a mathematically grounded research program waiting for empirical traction.

Your instinct that it sits on the boundary is exactly how many physicists see it. The real dividing line isn’t elegance—it’s whether, sooner or later, nature is forced to answer it.

Maybe we should make a separate academic field called "String Theory," perhaps in Mathematics or in Physics or maybe all on its own.

That suggestion isn’t as radical as it sounds—in practice, something very close to it has already happened.

String theory today behaves less like a single, testable physical theory and more like a research program spanning physics and mathematics. In many universities, the people working on it sit in physics departments, but their day-to-day work often overlaps heavily with pure mathematics—sometimes more than with experiment-driven physics.

There’s even a recognizable subculture sometimes called “string mathematicians”: people who use string-theoretic tools to prove or inspire results in areas like geometry or topology, with little immediate concern for experimental verification.

So your instinct—to separate it out—captures a real tension:

Physics, at its core, is empirical. It ultimately answers to experiment.
Mathematics answers only to internal consistency and proof.

String theory sits awkwardly between those two stools.

Creating a distinct field—call it “String Studies” or something less whimsical—would have some advantages. It would be intellectually honest about what’s going on: a body of highly structured, mathematically rich ideas whose connection to physical reality is still uncertain. It would also remove some of the friction inside physics, where critics argue that too much attention and funding has gone to something not currently testable.

But there are also reasons scientists have resisted formalizing that separation.

One is historical precedent. The boundary between mathematics and physics has always been porous. Isaac Newton wouldn’t have recognized a clean distinction; nor would Albert Einstein, whose work was deeply mathematical but relentlessly aimed at physical reality. New mathematical structures often precede experimental confirmation by decades.

Another is strategic: if you formally exile something from physics, you risk cutting it off from the very empirical discipline that might eventually test it. Keeping string theory inside physics is, in part, a statement of intent: “this is supposed to describe the real world, even if we’re not there yet.”

And finally, there’s a sociological reality. Academic fields don’t reorganize themselves cleanly based on philosophical clarity. They evolve through funding streams, hiring patterns, and intellectual fashion. String theory already has its journals, conferences, and networks—it’s effectively a semi-autonomous domain without needing a new label.

If I were to sharpen your idea rather than dismiss it, I’d say this:

Instead of carving out a new field, it might be more useful to adopt clearer categories within physics itself—something like:

• empirically grounded theory

• speculative but testable-in-principle theory

• mathematically driven exploratory frameworks

String theory would sit squarely in that third category, without pretending to be something it currently isn’t.

That keeps the door open without blurring the standards.

Your instinct, though, is pointing at a genuine issue: science doesn’t just need good ideas—it needs clarity about what kind of idea it is dealing with.

Well, then, kindly let me dismiss it. The thing is it is so developed and still so far from demonstrated, it seems a pity. It probably is true, too, but it will be a good long while.

You can dismiss it—but I’d nudge you not to write it off so much as to reclassify it in your mind.

What you’re reacting to—the sheer elaboration of the structure, combined with its distance from experiment—is exactly what makes people uneasy. It feels like a cathedral built on land no one has yet confirmed is even there.

But that doesn’t make it wasted effort, and it doesn’t even make it unlikely to be true. It just means it’s operating on a very long fuse.

There are really three separate judgments tangled together in what you said:

First, “it’s a pity.”
Yes, in a very human sense. Physics is most satisfying when theory and experiment dance together—proposal, test, correction, repeat. String theory has been mostly a solo performance. That’s aesthetically disappointing to people who like closure.

Second, “it probably is true.”
Here I’d gently push back. There’s no real evidential basis for assigning it a high probability. What we can say is that it’s one of the most internally consistent attempts to unify quantum mechanics and gravity. But nature has fooled elegant thinkers before. Consistency narrows the possibilities; it doesn’t pick the winner.

Third, “it will be a good long while.”
That’s the safest part of your statement. Even optimistic routes to testing—cosmological signatures, subtle imprints in gravitational phenomena—are technically daunting and may remain ambiguous. So yes, if string theory connects to reality, confirmation is likely to be indirect and slow.

What keeps it from being a dead end is that it has already paid off in unexpected ways. Work motivated by string theory has clarified black hole thermodynamics, quantum field theory techniques, and even bits of pure mathematics. So even in the worst case—if it turns out not to describe our universe—it may still be remembered as a remarkably productive wrong turn.

There’s a precedent for that. The 19th-century vortex theory of atoms (associated with William Thomson, 1st Baron Kelvin) was elaborate, mathematically rich, and ultimately incorrect—but it helped stimulate developments that mattered later. Science sometimes advances by overreaching.

So perhaps the most balanced stance is this:

Treat string theory as a powerful, highly disciplined speculation—one that has earned the right to be taken seriously, but not the right to be believed.

And then let time do what it always does in science: either drag it down to earth, or quietly let it fade while its useful pieces get absorbed into the rest of the structure.