When it comes to science and the supernatural, the common consensus is that the two areas are polar opposites and will never meet. The area of quantum mechanics, which is approaching the ripe old age of 200 years, continues to provide a great deal of confusion within the scientific community as to what it is that makes such an utterly baffling concept possible.

Quantum in a Nutshell

Quantum mechanics is, at its core, an explanation of why particles act the way they do. In classical mechanics a wave will always act like a wave, that is, it will always travel at the speed of light with some frequency and respective wavelength and will experience effects such as refraction, reflection and diffraction. Similarly, a particle in classical mechanics will always act like a particle; a solid mass with a momentum. Quantum mechanics is used to explain the motion of particles that are so small they do not act like a particle or a wave, but rather as both.

Now you may be thinking “big deal, particle go brrr” but I can assure you it gets weirder. In order to illustrate why the scientific community was and remains to be so perplexed by this field, we must first observe the results of the double slit experiment, the first example of wave-particle duality.

The Double-Slit Experiment

First performed by Thomas Young in 1802, the double slit experiment, as the name suggests, uses two slits in the surface of a solid material to create and interference pattern from an incident beam of light. This experiment was revolutionary in observing the physical properties of wave motion.

Figure 1: Young’s Double Slit Experiment. Credit: [1] eiu.edu

In 1927, in an experiment performed at Western Electric by Clinton Davisson and Lester Germer, it was proven that electrons could undergo diffraction and produce a diffraction pattern, thus proving the hypothesis of wave-particle duality, a fundamental building block of modern-day quantum mechanics. In 1961, the double slit experiment was carried out using a beam of electrons instead of light in order to see if they would produce the same result. Sure enough, the electrons produced an interference pattern on the screen.

So Young’s experiment shows us that electrons behave like waves. But we know that electrons interact with other particles in the same way a particle would. This wave-particle duality is what gives rise to the quantum-mechanical theory. An electron may act as either a particle or a wave at any given time. The real question is does an electron know when it has to act like one or the other? A common thought experiment details a detector being placed at the two slits so that the electron is observed going through the slit. Hypothetically, the interference pattern would not appear on the other side as before since the electron is observed passing through the slit in the form of a particle and therefore must continue to act like a particle. Richard Feynman used this thought experiment to prove that an electron must always act like a wave in this circumstance since this thought experiment cannot possibly be performed due to the impossibly small scale ([2] Harrison, 2006).

Varying Interpretations

Feynman’s thought experiment can cause some confusion as it gives the impression that an electron could choose to act like a particle at the slit because it somehow knows it is being observed. Similar to other natural phenomena, if left unexplained by physics, many will jump to believe that a higher power could control such behaviour. Science has always been used to explain natural phenomena that were previously considered to be acts of witches, gods or the supernatural.

The idea that a particle could be granted some form of consciousness by a higher power is something that would very much excite those who believe in or are searching for a god. Simply put, however, that’s not how it works. The particle does not “choose” its state, it simply is. If placed in a certain condition where a wave will experience a certain effect (as in the double slit experiment) it will do so and will undergo the same process as anything else with wave motion. Like when a non-Newtonian fluid is put under stress, it will alter its form to adapt to its surroundings. An electron is still a particle but simply acts like a wave sometimes.

The probabilistic nature of quantum mechanics does give rise to some theories about alternate worlds in which fundamental particles were to act like particles where they would act like waves in our world. This “Many Worlds” theory is more the stuff of science fiction as there is truly no way for it to be proven. The fact that it cannot be disproven, however, is an interesting notion that finds itself appearing more in cinemas than in the lab.

The Final Message

The scientific community’s interpretations of quantum mechanics vary from the perfectly normal to the apparently bizarre. The notion that this field of study could prove the existence of parallel dimensions seems to be pulled directly out of science fiction. The idea that a particle can choose its state of being gives rise to a plethora of philosophical and potentially religious questions.

Quantum mechanics is clearly the most vital area of physics today and the sooner we can come to an explanation that can be understood by all, the better.

References

[1] Dr. Doug Davis, Adventures in Physics, 20.2 Young’s Double Slit, East Illinois University. https://ux1.eiu.edu/~cfadd/3050/Adventures/chapter_20/ch20_2.htm

[2] David M Harrison, 2006, The Feynman Double Slit, Dept. of Physics, University of Toronto. https://faraday.physics.utoronto.ca/PVB/Harrison/DoubleSlit/DoubleSlit.html