“…And then he ran out.
And, then, fast as a fox
The Cat in the Hat
Came back in with a box.”
Before we really dive into this there is something you should understand: Schroedinger’s only goal in 1935 was to bitch to Einstein about how blind their contemporaries were to the nature of reality. If someone told him that almost 100 years later we would still be talking about his cat, putting it on T-shirts, creating memes about it, he would have been appalled. First he may have asked us to explain what a meme is, but then, certainly, he would have been appalled.
Schroedinger was awarded the Nobel Prize in 1933 along with Paul Dirac1 for their individual work on atomic theory. Schroedinger’s equation,2 which describes the wave function of an electron, is a cornerstone of quantum mechanics. In the marbled halls of science Schroedinger is remembered for this equation. In the real world we have distilled his work down to a cat in a box, which may or may not be dead.
If the thought of a cat being both dead and alive leaves you with an uncomfortable feeling in your stomach, like seeing friend get sick after eating the same meal you did, you are not alone. That a particle at the quantum level can exists in multiple states, a term called superposition, has, however, been shown experimentally.3
In 1933, Albert Einstein, Boris Podolsky, and Nathan Rosen wrote a paper referred to as the EPR article. In this article they stated their general distaste for quantum mechanics in its current form. Their complaints were not unreasonable. They wanted to believe in a reality in which there is an underlying truth, regardless of who or what is observing it.4 Can we blame them? Hardly. Does that make them right? The road to dissertations is paved with good intentions.
According to the commonly held belief of the time, often referred to as the Copenhagen Interpretation,5 any particle can exists in more than one state, and, until observed, exists in all of them. If you think about this for too long you’ll find yourself needing a little DMZ6 just to find your way back to normal.
Perhaps in an effort to align himself with the time’s most ingenious thinker, Schroedinger wrote Einstein a letter supporting the EPR article and proposing the following thought experiment: Imagine there is a sealed box with a cat inside. Along with the cat there is a single radioactive particle. If the particle decays it will cause a poison to be released and the cat will die. However, there is equal probability that the particle will not decay and the cat will not die.
The state of the radioactive particle can be described as a wave function containing all of the information for both the decayed particle and the whole particle. According to the Copenhagen Interpretation this means that until an observer opens the box to check on the cat, causing the wave function of the particle to collapse into a single state, the cat is simultaneously alive and dead.
And so here we are. With a cat, in a box, that we can’t see, that might be dead, that might be alive, and a headache. You don’t have to believe this is true. In fact, it’s not, no one has yet worked his or her way up to a cat-sized grouping of particles in a lab to demonstrate the theory. But we do know it’s true for one particle. And if it’s true for one particle… well, you see where I’m going with this. Any high school math student can tell you there is more than one way to solve a problem, but every problem only has one answer. Or, more aptly perhaps, there is more than one way to skin a cat, but you end up with the same bloody result.7
In corners of the Internet, overlit with fluorescent bulbs, sick and illiterate people debate the shape of the Earth and Kubrick’s Moon landing. But elsewhere, scientists offer up other explanations for how and why quantum realities can be applied to our experienced realities. The many worlds theory suggests that the wave function never collapses at all; it simply exists in different states in a parallel reality we’re not aware of.8 Alternately, the “observer” in the experiment can be the experimenter or the cat, indicating that for each observer a different reality exists, with micro realities specific to the observer. This theory is popular among the anthropomorphic crowd. Currently, there is not a single agreed-upon theory of quantum superposition. At least not in this reality.
Jennifer Teubl is a recovering English major/Sommelier/Molecular Biologist who loves to code, works in finance, and believes the cat is dead.
1 Dirac is known as much for his social ineptitude as for his genius. The Dirac equation predicted the existence of antimatter several years before its existence was experimentally proven. When giving a lecture a colleague said, “I don’t understand the equation in the top right-hand corner.” After several moments of silence the moderator asked Dirac if he could answer the question to which Dirac responded, “There was no question asked. That was a comment.”
3 Starting with the double slit experiment first done in 1801 by Thomas Young. Long before quantum physics Young showed that light could behave as both a wave and a particle. This laid the groundwork for researchers to eventually view all matter as having properties of both waves and particles. Most people will tell you that organic chemistry is the gatekeeper of higher science learning. They’re wrong; it’s the double slit experiment.
4 There is a well-known quote of Einstein’s: “God does not play dice.” I have read several different accounts detailing when, and to whom, this phrase was said. The one I like best takes place at the 5th Solvay conference in 1927, in which after Einstein’s remark Niels Bohr responded “Einstein, stop telling God what to do.”
5 First referred to by Heisenberg as the “Copenhagen spirit of quantum theory” in a 1930 publication. It is assumed to refer to the work done by him and Bohr during their time at Bohr’s institute in Copenhagen in the 1920s. For more on this one should read “Copenhagen,” a play by Michael Frayn that imagines, entertainingly, a conversation between Bohr and Heisenberg in the shadow of a world about to go atomic. I found my copy at Goodwill for $1.99 where it had been yellowing on a shelf next to John Grishams’ greatest hits. You may want to find yours on Amazon.
6 An extremely potent hallucinogen most well known for its implication in the demise of Hal Incandenza’s promising tennis career. It is derived from a mold found only to grow on other molds.
7 This proverb is rooted in a similar proverb from the 17th century: There are more ways to kill a dog than hanging. It serves as a reminder that the 1800’s were a terrible time to be alive.
8 This is a personal favorite of mine, because it means there is a reality in which 14-year-old me kicked Nancy Sullivan’s ass for calling me fat instead of crying in a bathroom stall.