On a friend’s recommendation, I am reading Lee Smolin’s The Trouble with Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next.
I haven’t finished the book yet — for someone with my non-science background, it can take quite a while to read a book like this. My finger can move over the words, while I say them aloud, only so fast.
But the parts that I have already read tie in rather nicely with two bits of news. First is the news that the infamous neutrino experiment of two months ago has been repeated with a smaller error window, and the neutrinos are still arriving at their destination faster than the speed of light.
This is, says the standard model, quite impossible. If these results stand up, Einstein’s theories that “prove” that the velocity of light is the absolute speed limit in the universe fall down.
The second piece of news will get much less coverage in the popular press, but it has a large but different kind of significance for the other “mega-theory” of physics — quantum mechanics. As reported on the Scientific American webpage, “At a conference in Paris on November 18, teams from ATLAS and the CMS experiments presented a combined analysis that wipes out a wide swathe of potential masses for the Higgs particle.”
And, the article continues, “Analysis of the very latest data from this autumn–which Murray isn’t yet ready to share — will scour the range that remains. If it turns out to be empty, physicists may have to accept that the particle simply isn’t there.”
Neutrinos that travel faster than light. No Higgs particle to unify the fundamental nuclear forces. And, as Smolin’s title suggests, an alternate, unifying theory — string theory — that’s impossible to verify or to disprove.
It’s enough to make one give up on reality altogether and go running as fast as possible into the comforting arms of Hawking’s “model dependent realism.” Well, not so comforting, it turns out. Even in a conceptual world that’s fine with no final physical reality, the models that work are the ones that best fit the experimental data — not the ones that don’t!
To come anywhere close to grasping the importance any of this, we could use a little help. And a form of mental first aid can be found in the first part of The Trouble with Physics.
The opening chapters of Smolin’s book deal as much with the “rules” of the scientific method as they do with the specifics of contemporary physics, and it’s in this first focus that we find our relevance to the new experimental results.
Einstein’s theories have been confirmed again and again by experimental data. Now, all of a sudden, we have data that don’t fit inside the theory. There aren’t many alternatives. Either the data is wrong in some way, or the theory is wrong in some way. And once a theory starts to go wrong, it’s seldom long until it has gone all wrong.
One of the characteristics of the physical sciences is that they attempt to describe the world as it really is, what Smolin calls “the real world out there.” His chief objection to string theory is that it (actually, they, and lots and lots of them!) can’t be tested by any method available to us with today’s technology.
In contrast, one virtue of Einstein’s relativity theories is that they are quite directly (if not simply) testable. Now, we have results that fall outside the theory’s predictions.
Why is this such a problem? Here’s where Smolin’s helpful.
Smolin distinguishes between “constructive theories” and “theories of principle.” Constructive theories are particular parts of a larger theory of principle. A constructive theory “cannot stand alone; it must be set within the context of a theory of principle.”
A theory of principle creates the framework for the explanation of all of the constructive theories of which it is composed. As such, “it must be universal.” In the simplest terms, one can have different constructive theories within one framework; but one can have just one framework at a time. If the framework isn’t universal, it all threatens to collapse.
The Higgs boson is a constructive prediction within the framework of its theory of principle, quantum mechanics. If it’s not there, something else may be. Some physicists have suggested alternatives, including that the Higgs is not a single particle but a representation of a group of even more fundamental particles. If there’s no Higgs, there’s still quantum mechanics, in an as yet unspecified different form.
In contrast, relativity is a theory of principle. In fact, it’s the existence of two different frameworks, one for the small and one for the large, that drives the search for a general unified theory. Scientists can’t accept that the laws of physics aren’t universal somewhere, on some level, with some mathematics. So science keeps looking for the way to unify them.
As Smolin writes:
The most cherished goal in physics, as in bad romance novels, is unification. To bring together two things previously understood as different and recognize them as aspects of a single entity—when we can do it—is the biggest thrill in science.
Smolin is skeptical that string theory can provide this thrill. After all, it can’t be verified experimentally. And that is — or was, until now — the great advantage of the relativity model:
Einstein’s general theory of relativity satisfied all the tests … for a successful unification. There were profound conceptual consequences, which were implied by the unifications involved. These quickly led to predictions of new phenomena, such as the expanding universe, the Big Bang, gravitational waves, and black holes, and there is good evidence for all of them.
Putting all of these ideas together, a failed search for the Higgs boson would be a disappointing but much less serious outcome than would be firm confirmation of a violation of the speed limit of the universe.
In the latter event, Smolin — and everybody else — would have to start looking for an alternative theory of principle, some new kind of universal framework for our understanding of physical reality.
That alternative might be string theory, but until string theory can be tested empirically, we’re left with a popular but unsupported speculation.
Maybe we could simply invent a Super-Force that generated spontaneously from a Super-Particle? Forget the science — when the going gets tough, fall back on an evidence-free assertion, a self-definable constant.
We could give it a short, easy to remember name.
Three letters would be about right, I’d say.