Is String Theory Falsifiable?

Is String theory falsifiable?

Is String theory falsifiable?

Check out this answer from Consensus:

The falsifiability of String Theory is an ongoing debate in the scientific community. The identification of physical and mathematical inconsistencies and the essential nonlocality of string field actions present significant challenges. While novel reformulations offer potential pathways to resolve these issues, the inherent complexities of String Theory make it difficult to definitively prove or disprove. As research continues, the question of whether String Theory can be falsified remains open, with implications for its status as a scientific theory.


String Theory has been a significant area of theoretical physics, aiming to reconcile general relativity and quantum mechanics. However, its falsifiability, a criterion for a scientific hypothesis proposed by philosopher Karl Popper, has been a topic of debate. Falsifiability requires that a theory can be proven false by an experiment or observation. This article explores the challenges to the falsifiability of String Theory.

Problematic Aspects of String Theories

Recent research has identified several problematic aspects of current noncanonical or nonunitary string theories. These include the lack of invariant units necessary for consistent measurements and the lack of preservation in time of Hermiticity-observability1. These inconsistencies raise questions about the empirical testability of String Theory, as any theory that cannot make consistent predictions is challenging to falsify.

Novel Reformulations of String Theories

To address these issues, novel reformulations of string theories have been proposed, utilizing iso-, geno-, and hyper-mathematics of hadronic mechanics1. These reformulations aim to resolve the current inconsistencies and offer new possibilities, such as an axiomatically consistent inclusion of gravity and the treatment of multi-valued, irreducible biological structures. If these reformulations can lead to testable predictions, they may enhance the falsifiability of String Theory.

Nonlocality in String Theory

Another challenge to the falsifiability of String Theory is the problem of nonlocality. All string field actions are essentially nonlocal, leading to unstable manifestly Poincaré invariant theories and a breakdown of Lorentz invariance2. The use of perturbation theory alters the causal and canonical structure of the covariant formulations, resulting in acausality2. This fundamental property of the light cone formalism suggests that certain aspects of String Theory may not be testable in a traditional sense, complicating its falsifiability.


Is String theory falsifiable?

Rafael Alves Batista has answered Extremely Unlikely

An expert from Oxford University in Cosmology, Astrophysics

String Theory (ST) is currently NOT falsifiable: it does not make any testable predictions. In the strictly positivist popperian view, it couldn’t even be regarded as science. However, there is a problem with the above reasoning: it disregards ST as science on the grounds of testability.

A scientific theory may be underdetermined, meaning that even though it might not be testable today (for reasons such as technological limitations, etc), it might in the future.

I use the word ‘testable’, but the argument applies more broadly for falsifiability as well. Because there are many versions of ST (okay, they can be unified within a single M-theory – or not), all of them are in principle equally valid, and there is no way to distinguish among them. Therefore, even if ST is actually the underlying structure of the physical world, it seems that it could never be unambiguously confirmed. So the argument that it is currently underdetermined but may be testable in the future seems not to apply.

Some people claim the axion is a testable prediction of ST. Indeed, it is. However, the detection or non-detection of the axion does not confirm nor reject ST, and therefore this cannot be considered a reliable test. On point to consider is the sociology of the ST community: many people are drawn to it for its aesthetically beauty and likely because this satisfies their ontological views. Adopting a more pragmatic stance, ST doesn’t make measurable predictions nor is falsifiable.

Maybe it is time for a new scientific theory that simply attempts to describe what we observe, rather than a theory attempt to describe the nature of reality – and that is not string theory. The real question is then: When should we abandon string theory? Should we abandon it at all?

Maybe in the future we’ll be able to test it. I personally doubt it, but I cannot be 100% sure we’ll not find/think of a measurable manifestation of ST. So I cannot say whether the theory is falsifiable – I strongly lean towards NO (it’s not falsifiable), but I wouldn’t be surprised if it a yes.


Is String theory falsifiable?

Joel Primack has answered Unlikely

An expert from University of California, Santa Cruz in Cosmology, Astrophysics, Quantum Physics

String Theory is based on supersymmetry, which is a very popular approach among particle physicists to go beyond what we call the Standard Model of Particle Physics. Thus String Theory is actually Superstring Theory.

The Standard Model — in which matter is made of quarks and leptons, which interact via the photon, W and Z bosons, and gluons, and which get mass from the Higgs boson — accounts for essentially all the results yet obtained from particle accelerators. But we know that the Standard Model is seriously incomplete; for example, there is no room in it for dark matter, the main form of mass in the universe.

Supersymmetry posits that all the fundamental particles of the Standard Model have partner particles whose interactions are analogous to those of their Standard Model particles — but which must have much larger masses, since none of the partner particles have yet been discovered at accelerators.

There are good, although not compelling, reasons to expect that the masses of the supersymmetric partner particles will be within the range of the Large Hadron Collider, so it is possible that supersymmetry will be discovered in the next few years — which would be very good news for Superstring Theory.

The late Heinz Pagels and I pointed out in a 1982 article in Physical Review Letters that supersymmetry naturally explains the dark matter as the least massive of the supersymmetric partner particles. This remains perhaps the most popular theory for the nature of the dark matter, and many experiments are testing it — another possible way to verify supersymmetry. But if supersymmetry were ruled out, that would falsify String Theory.

There are a number of different experiments currently underway that are looking for possible effects of supersymmetry. Evidence from them could support supersymmetry, but I know of no current experiments that are capable of disproving supersymmetry. Thus supersymmetry is unlikely to be ruled out any time soon, although evidence could emerge supporting alternative theories — and that could make supersymmetry less plausible.

Subscribe to
Our Newsletter