The claims of Einstein’s theory of special relativity defy common sense. Clocks tick at different rates depending on your speed. All objects (including people!) moving at near light speeds shrink in the direction of motion. And light travels at the same speed for everyone, independent of motion.
Quantum mechanics, the theory of nature on atomic scales, is equally if not more bizarre. The equations of quantum mechanics do not calculate things like mass, force, velocity, or position; they measure our “knowledge.” The principle of complementarity says that a single, clear, realistic picture of atomic phenomena is impossible, and we are stuck with mutually exclusive descriptions. For instance, electrons are both particles and waves.
On the heels of such counterintuitive theories, stranger stuff has emerged. Some have suggested that traveling faster than light may be possible, which will make time go backwards. Others have claimed that the outcome of every atomic interaction remains “undecided” until observed by a conscious observer. Or perhaps for each undecided atomic interaction every option is selected simultaneously and in multiple ways, creating multiple universes. And string theory posits that the physical world is made up of ten dimensions instead of the usual three.
This is strange stuff. But the strangeness is embraced by scientists, not just popular science magazines and Internet hacks. Consider the following quotations (taken, I admit, out of context):
I could only say that I did not really know what was meant by “understanding” in physics. The mathematical framework of relativity theory caused me no difficulties, but that did not necessarily mean that I had “understood” … The whole thing baffled me, and struck me as being quite “incomprehensible.” (Werner Heisenberg, Nobel Laureate, in Physics and Beyond, Harper and Row, New York, 1972, p. 29.)
We must be clear that when it comes to atoms, language can be used only as in poetry. (Niels Bohr, physicist, philosopher, and founder of quantum mechanics, as recollected by Heisenberg in Physics and Beyond, Harper and Row, New York, 1972, p. 41.)
When the province of physical theory was extended to encompass microscopic phenomena through the creation of quantum mechanics, the concept of consciousness came to the fore again. It was not possible to formulate the laws of quantum mechanics in a fully consistent way without reference to the consciousness.” (Eugene Wigner, Nobel Laureate, in Symmetries and Reflections, Ox Bow Press, 1979, p.171.)
Time travel used to be thought of as just science fiction, but Einstein’s general theory of relativity allows for the possibility that we could warp space-time so much that you could go off in a rocket and return before you set out. (Stephen Hawking, https://parade.com/37704/parade/12-inside-a-great-mind/.)
There does seem to be a sense in which physics has gone beyond what human intuition can understand. We shouldn’t be too surprised about that because we’re evolved to understand things that move at a medium pace at a medium scale. We can’t cope with the very tiny scale of quantum physics or the very large scale of relativity. (Richard Dawkins, https://www.theguardian.com/science/2010/sep/11/science-david-attenborough-richard-dawkins.)
What are we to do with such strangeness? I have struggled with this question for many years, beginning, I suppose, when I first encountered special theory of relativity in my college physics class. I was studying Einstein’s theory, and some aspects of the theory did not sit right with me. I distinctly recall going through this line of thinking: First, I knew that relativity theory had to be true. It was in all the physics books. Everyone agreed it was true, and Einstein was the most famous physicist of the twentieth century. Second, I knew that the theory did not seem to fit with my common sense and intuition. There were equations that could be used to calculate things, but I had no realistic mental model for those equations. And something like this was probably part of my thinking, as well: If I am in a rocket ship with a laser beam shooting out the front of my ship, I can use my ACME laser-beam-measuring kit to determine that the laser light is traveling at 186,000 miles per second. So far so good. If now Wile E. Coyote zips by in his rocket moving at 185,000 miles per second in the same direction as the beam, he can use his own ACME laser-beam-measuring kit to measure the speed of my laser beam. His measurement is not 1000 miles per second as one might expect. Instead, he measures 186,000 miles per second. Yep. That’s weird. Oh, and just to add insult to injury, if Roadrunner came zipping by in the opposite direction, toward me, at say 185,000 miles per second, then he will measure the beam moving toward him at, you guessed it, 186,000 miles per second. Beep! Beep!
What was my response? Only one possibility was available to me at the time: my common sense was faulty. I made the same move Dawkins and others have made. Because common sense is derived from experience, and my experience is limited to speeds much less than that of light (meter sticks don’t shrink and clocks don’t slow down in my experience), I told myself that if I had grown up moving at speeds close to the speed of light, then I would have developed a totally different intuition and common sense. I decided that since my experience was so limited, I should not expect a realistic mental model.
As my scientific training continued, similarly incomprehensible conclusions confronted me in my quantum mechanics classes. But since I had already thrown out any reliance on common sense, the strange things I was taught in those classes were easier to swallow. “Stick with the equations, and solve the problems,” I thought, “Don’t worry about it making sense.” It did not sit well with me, but I didn’t see any other options.
Many years later, I began teaching two science seminars at Gutenberg College. We studied Einstein’s theory of relativity one quarter and quantum mechanics in another. We approached these subjects historically and with an eye to philosophy of science. The goal was to understand how science works, not the mathematical specifics of the theories. As a physicist, this was dangerous ground for me. After all, physics is a “hard science,” and philosophy is, in the words of one of my undergraduate professors, “fuzzy studies.”
The first time I taught the seminars was hard going; I had little experience with philosophy. But one of the huge advantages I had over the students—even greater than having a physics background—was covering the same material over and over again. And as the years passed, I began to come to the profound realization—which in hindsight may seem obvious but was not obvious at the time—that the development of the theories of special relativity and quantum mechanics were profoundly influenced by philosophy and culture.
Consider first the theory of special relativity. When Einstein first published his theory, other physicists had already been working in the field for many years. One, Dutch physicist Henrik Lorentz, had made a great deal of progress in understanding how electrical and magnetic phenomena are affected by speeds close to the speed of light. At the root of his researches was the belief that there was an all pervasive, fixed ether through which all things traveled. This ether was the medium for light waves, much as water is the medium of ocean waves. Lorentz’s research led to some interesting conclusions. First, the equations of electricity implied that when moving at high speeds relative to the ether, electrical forces diminished. Second, based on all the evidence available at the time, he concluded that the forces which kept atoms together were electrical. Both these conclusions turned out to be correct in essence. The combination of these two conclusions allowed Lorentz to deduce that matter moving at high speed relative to the ether shrinks due to the change in the internal forces. His equations relating to this deduction have been labeled the “Lorentz equations,” and they form the basis of Einstein’s theory of relativity. The shrinkage of matter was a strange result but easily imaginable by common sense.
Einstein took a different approach. Rather than making any claims about matter, he relied heavily on the importance of having simple and elegant equations and principles. Because a complete, commonsense theory of the forces within matter was messy and intractable, some other guidance was required. For Einstein, mathematical aesthetics took the place of common sense.
The impetus for such a move came from two sources. First, Einstein had read the philosophy of Austrian physicist and philosopher Ernst Mach, who claimed that mathematical equations were convenient formulations of measurements, but they did not represent any underlying reality about the nature of the world. Physics was about equations and measurements, period. Everything else was metaphysical mumbo jumbo. Second, Einstein was influenced by the spirit of mathematical formalism championed by German mathematician David Hilbert. Hilbert, an intimate friend of Einstein’s teacher and collaborator Minkowski, believed that all mathematics should be based upon first principles, called “axioms.” Every mathematical conclusion was to be deduced by clear logical steps from the axioms. This was a common belief. Formalists took this belief one step further by insisting that the axioms could not be based on the physical world, intuition, or the logic built into our minds. No, axioms were freely chosen. Good axioms allowed for beautiful mathematical structures. Bad axioms either led nowhere or to contradictions. Mathematics was completely detached from common sense or experience.
Einstein was a young, brilliant man whose commitments and beliefs were formed in this intellectual milieu. Thus it was a simple step for him to elevate the elegance and fruitfulness of mathematical principles to the guiding light for his physics. And he did just that. He proposed two axioms for his theory: 1) mechanical and electrical experiments that are identical in every way except for the speed of the laboratory (reference frame) have identical results; and 2) the speed of light is independent of the speed of the reference frame. Since, according to Einstein’s axioms, no one can claim their reference frame is preferred or “at rest,” there must be no preferred ether-based frame of reference, as Lorenz believed. From his two principles, however, Einstein was able to derive Lorentz’s equations. The two men arrived at the same mathematical equations but from different starting points. The history of how Einstein’s theory was chosen over Lorentz’s theory by the physics community is too complex to discuss here. I will simply suggest that philosophical and social components influenced that process.
So then, a viable, realistic interpretation of the phenomena of relativity theory existed—Lorentz’s ether theory. It had some problems early on, but these problems were being tackled. The measurable conclusions of ether theory were identical to the measurable conclusions of Einstein’s theory of special relativity because all measurements are based on the Lorentz equations. While I cannot claim that we should abandon Einstein’s presentation for that of Lorentz, I am willing to say that looking at the history and philosophy of the origins of the theory gives us a chance to re-ask whether throwing out a commonsense mental model is required by modern physics.
A similar situation arose regarding quantum mechanics. The results of quantum mechanics defied a rational, commonsense model. And for many, this counterintuitive and arational aspect was seen not as a problem but a welcome feature of the theory.
Of the many scientists who created the theory, Niels Bohr was probably the one most responsible for its strangeness. Bohr championed a perspective he called “complementarity”; that is, any event or physical change in a microscopic system should be described in complementary ways. No single, rational, and clear description could capture the essence of the phenomena. Take for instance the motion of an electron in an atom. In one experiment, it behaves as a particle. In another, it behaves as a wave. Bohr was adamant that no deeper explanation was possible, and we should embrace the mutually exclusive accounts. The wave description complemented the particle description. Neither is wrong, and neither is right. Ultimately, Bohr said, our language and concepts are insufficient for the task, and we are reduced to “poetry.”
A second important development along these lines was the interpretation of the Schrödinger equation, which is used to make predictions about atomic phenomena and the outcomes of measurements. German physicist and mathematician Max Born advanced the interpretation that the equation calculates our “knowledge of the system.” It does not calculate things like positions of atoms or speed or energy. Instead, according to Born, the Schrödinger equation calculates probabilities. As with complementarity, this interpretation abandons the possibility of a clear, imaginable, realistic picture of atomic phenomena. Further, Bohr and others insisted that they had “proved” that no clear realistic picture would ever be possible.
Despite the confidence of men like Bohr and Born, and despite the acceptance of these ideas among the majority of physicists at the time, some hold-outs did not agree with these ideas—among them Einstein and Schrödinger. In the 1950s, another scientist, American physicist David Bohm, came up with a counter theory that was far more intuitive and understandable than the approach espoused by Bohr. Bohm’s pilot-wave theory explained the seemingly irreconcilable particle-wave behavior in a simple, intuitive, and obvious way. He showed that nature did not demand that we abandon a realistic understanding of the world.
What can we conclude from our examination into the origins of relativity and quantum mechanics? After all, schools teach Einstein and Bohr, not Lorentz and Bohm. Realistic mental models of phenomena are out of fashion (hence the creation of a ten-dimensional string theory!). The physics community largely decided against realism even though viable realistic alternatives existed. Shall we embrace a skeptical attitude toward physics and say that all our theories are simply ways of calculating, not descriptions of an underlying reality? Shall the existence of alternatives lead us to doubt the possibility of finding a true theory? It is tempting to go that route.
However, my point is the opposite. We should not give up on creating descriptions of the world that can be imagined realistically. The fact that realistic options existed is encouraging, not a source of skeptical despair. I am aware now, more than ever before, of the philosophical commitments at the beginning of the twentieth century and how those commitments influenced the decisions of physicists. Perhaps if the philosophical commitments of the time had been different, we would have theories more akin to those of Lorentz and Bohm. We will never know.
My philosophical commitments are strongly realistic. I believe that the history of science has shown that a great deal of rational order is built into the universe. Theories with arational elements are few and very recent, deviations from the norm. Further, the Bible’s hints about the nature of God suggests that God intended to create a beautiful and orderly world. Thus I am a hold-out on both the theories of special relativity and quantum mechanics, and I hope for a time when realism once again comes back into fashion. Perhaps such a hope is naive, but I am waiting for a clear, realistic theory combining relativity and quantum mechanics to emerge that will dispel many of the perplexing problems currently plaguing particle physics. For now, however, I need not abandon commonsense realism as I felt compelled to do as a youth. Instead, I will marvel at the order, beauty, and complexity of the physical world and trust that someday I will have a chance to ask the Creator all about it.