String theory and M-theory are highly theoretical at the moment, but could give us enormous insight some time down the line. As any hypothesis it makes certain predictions (i.e. it is falsifiable), but we do not yet have the technology to test it.
To quote wikipedia: "String theory as a theory of everything has been criticized as unscientific because it is so difficult to test by experiments. The controversy concerns two properties:
1.It is widely believed that any theory of quantum gravity would require extremely high energies to probe directly, higher by orders of magnitude than those that current experiments such as the Large Hadron Collider can reach.
2.String theory as it is currently understood has a huge number of equally possible solutions, called string vacua and these vacua might be sufficiently diverse to explain almost any phenomena we might observe at lower energies.
If these properties are true, string theory as a theory of everything would have little or no predictive power for low energy particle physics experiments. Because the theory is so difficult to test, some theoretical physicists have asked if it can even be called a scientific theory. Notable critics include Peter Woit, Lee Smolin, Philip Warren Anderson, Sheldon Glashow, Lawrence Krauss, and Carlo Rovelli.
All string theory models are quantum mechanical, Lorentz invariant, unitary and contain Einstein's General Relativity as a low energy limit. Therefore to falsify string theory, it would suffice to falsify quantum mechanics, Lorentz invariance, or general relativity. Hence string theory is falsifiable and meets the definition of scientific theory according to the Popperian criterion. However to constitute a convincing potential verification of string theory, a prediction should be specific to it, not shared by any quantum field theory model or by General Relativity.
One such unique prediction is string harmonics: at sufficiently high energies—probably near the quantum gravity scale—the string-like nature of particles would become obvious. There should be heavier copies of all particles corresponding to higher vibrational states of the string. But it is not clear how high these energies are. In the most likely case, they would be 10^15 times higher than those accessible in the newest particle accelerator, the LHC, making this prediction impossible to test with a particle accelerator in the foreseeable future."
In other words; unless you are seriously interested in physics, and more accurately quantum physics, I would wait until we have something more solid to go on here. ;)
