The Skeptical Teacher

Musings of a science teacher & skeptic in an age of woo.

Testing String Theory? How Real Science Progresses

Posted by mattusmaximus on September 16, 2010

Something very interesting has happened recently in the world of theoretical physics.  One of the hottest ideas around is the notion of so-called string theory: it’s the idea that all matter & energy in the universe – from the electrons & quarks that make up atoms to photons of light to everything in between – is composed of ultra-tiny strings of vibrating energy.  It’s a marvelous and mathematically elegant idea, one which many theoretical physicists believe holds the key to unifying the fundamental forces of nature, but it suffers from a big flaw: these strings are, according to the theory, so small that we have no way to experimentally detect them. Thus, if such is the case, then many physicists & critics of string theory have equated the idea with a dragon in the garage, an unfalsifiable notion which isn’t subject to scientific investigation.  I have placed myself into this category of string theory skeptics for quite a long time for this very reason…

… up until now, that is.  It seems that the question of whether or not string theory is testable, and therefore real science, has been answered.  That’s because recent theoretical analysis of string theory has revealed that it makes unique predictions which can be tested in a controlled laboratory setting having to do with a weird phenomenon called quantum entanglement. Up until now, physicists haven’t had a good way to really predict the behavior of systems that coupled via quantum entanglement, but it seems that some aspects of string theory can shed some light on this…

New study suggests researchers can now test the ‘theory of everything’

String theory was originally developed to describe the fundamental particles and forces that make up our universe. The new research, led by a team from Imperial College London, describes the unexpected discovery that string theory also seems to predict the behaviour of entangled quantum particles. As this prediction can be tested in the laboratory, researchers can now test string theory.

Over the last 25 years, string theory has become physicists’ favourite contender for the ‘theory of everything’, reconciling what we know about the incredibly small from particle physics with our understanding of the very large from our studies of . Using the theory to predict how entangled quantum particles behave provides the first opportunity to test string theory by experiment.

“If experiments prove that our predictions about quantum entanglement are correct, this will demonstrate that string theory ‘works’ to predict the behaviour of entangled quantum systems,” said Professor Mike Duff FRS, lead author of the study from the Department of Theoretical Physics at Imperial College London.

“This will not be proof that string theory is the right ‘theory of everything’ that is being sought by cosmologists and particle physicists. However, it will be very important to theoreticians because it will demonstrate whether or not string theory works, even if its application is in an unexpected and unrelated area of physics,” added Professor Duff. …

I bolded Professor Duff’s comment in that last paragraph for emphasis, because it illustrates a very important point.  Namely, if these experiments on quantum entanglement are run and found to conform to the predictions of string theory, then that doesn’t necessarily prove string theory – instead, what it does is give us some real confidence in some aspects of string theory, and – hopefully – it will also lead us to some other insights and possible tests in the future.  But, to me, the really important thing here is that string theory is no longer a dragon in the garage, because now it is entering the realm of empirical examination via experimentation.  And that’s a huge step.

For people to understand this progression of string theory from an elegant mathematical notion that, while it was very aesthetically pleasing it was essentially non-testable and therefore (at best) questionable science, to a much more robust & respectable theory that actually makes testable predictions, I find it apt to reference a historical analogy: Einstein’s theory of relativity.

In 1915, Albert Einstein formulated & published his general theory of relativity, which is currently the most well-respected & thoroughly verified theory of gravity to date.  However, at the time that he published his ideas, they were highly abstract and very mathematically complex – just like modern-day string theory.  In fact, many physicists thought that Einstein’s ideas were little more than crackpot stuff and were openly skeptical of the description of the universe put forth by relativity.  Yet relativity did make some testable predictions, and when – in 1919 – the first such test of general relativity took place (the gravitational lensing of starlight during that year’s solar eclipse) and was found to verify the predictions of the theory, a lot of critics of Einstein’s ideas began to think twice.  Within a few years, because of the power of relativity’s testability, this new theory of gravitation went from being almost scorned within the physics community to the realm of a much more respected & useful idea.

I like to think of string theory in much the same way.  For many decades now, string theorists have been doing a lot of really amazing mathematical work, but there just hasn’t been anything really solid in the way of testable predictions, which is exactly the kind of thing that critics like me have been looking for.  However, with these new developments, I’m happy to say that I must look at string theory in a new light – it is now a much more solidly scientific notion than before.  Now, I’m not saying that string theory is correct and provides an accurate view of the universe; anyone who says this based upon what’s known to date is, in my opinion, grasping at straws.  However, we can now see that we have a way to check to see whether or not string theory, or aspects of it, might be correct.

Folks, this is how real science works.  many pseudoscientists & cranks often moan about how the “scientific establishment” is keeping them down, or how there’s some conspiracy to conceal the “truth of their discovery”.  But for all their melodrama, these cranks and weirdos can never seem to come up with the scientific goods that skeptics are looking for: a way to actually test out their ideas.

The lesson here is simple: if you want your idea to gain any scientific validity, answer the questions of whether it is falsifiable and how to go about testing it.  Without that, it may be a very elegant & appealing idea, but don’t call it science.

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