Schrodinger’s quantum cats and their implications for reality

Quantum physics is a fascinating branch of modern science that has grown in popularity. Terms such as “the uncertainty principle”, “quantum entanglement” and “probability waves” have all become commonly-used phrases in the scientific community. In the same way that Newtonian mechanics explains the world of the very big, (the orbits of planets, falling apples) quantum physics aims to improve our understanding of the very small (sub-atomic scales). Once objects start interacting at a smaller level, quantum mechanics takes over and produces some weird and wacky results. What Newton’s laws and (to an extent) Einstein’s special and general theories of relativity have in common sense and comprehensibility, quantum physics makes up for in its plain weirdness.

In the wacky world of the quanta, particles appear out of nothing and vanish again in an instant. Particles separated by infinite distances show characteristics of ‘entanglement’; that is, measurements taken on one particle instantaneously affect the state of the partner (seemingly violating the faster-than-light limitations of general relativity). Similarly, quantum particles exhibit tunneling behaviours. Being probabilistic in nature, the quantum wave equation for any given particle will expand as a function of time. Occasionally, this wave (or probability of existing in a particular position) will penetrate insurmountable obstacles (that is, distances or barriers where the energy to escape them is more than the particle’s kinetic energy). In effect, the particle has ‘tunnelled’ through thin air.

The probabilistic nature of quantum physics introduces some worrying implications for the nature of reality. In particular, the Copenhagen Interpretation (one leading view on what the quantum calculations translate into in the macroscopic world) posits that an observer is needed to collapse the wave functions, creating what we see as real. Taken literally, this means that nothing exists if we aren’t watching. The falling tree in a deserted forest really does make no sound, solving the Chinese proverb succinctly. Erwin Schrodinger, one of the pioneers of quantum theory and the man behind wave equations, disagreed with this interpretation most vehemently. Schrondinger’s cat was the fruits of his protest; a thought experiment introducing the paradox that this interpretation brings.

Schrodinger’s thought experiment goes a little something like this. It states that a cat, sealed off totally from the outside world and attached to a death device will exist in a superposition of quantum states. Its probabilty wave will spread out over time, with the cat existing as both dead and alive at the same time. The hypothetical death device consists of a decaying radioactive source, emitting particles that are detected via a Geiger counter. The probabilty wave spreads in such a manner due to the underlying quantum randomness that controls the process of radioactive decay (tunnelling allows beta particles to escape the overwhelming pull of the weak nuclear force). Thus, once a sufficient period of time has passed and the probability of the radioactive substance emitting a particle (or not) is exactly 1/2, the cat is said to be both alive and dead.

Schrodinger was not advocating the truth of this experiment, rather using it instead to draw attention to the paradox and ‘can of worms’ that the Copenhagen Interpretation had brought about. While the experiment may indeed be possible in the realm of quantum uncertainty, it certainly requires a definite leap of faith away from the common sense interpretation of everyday occurances. The major premises that this argument requires us to accept is that a) probability waves exist (that is, quantum particles exist in a superposition of possible states), b) an observer is necessary to collapse the function and bring about reality and c) the observer must be intelligent (namely that there is something inherently unique about conscious beings and their quantum-collapsing ability).

Firstly I will take a minor detour and actually lend a snippet of support to the thought experiment. The old saying ‘a watched pot never boils’ seems to make no practical sense, however a simple rephrasing to ‘a watched quantum pot never boils’ is closer to the truth. Researchers imitated the physical process of boiling on a quantum scale by bombarding a collection of beryllium atoms with microwaves. These incoming microwaves were then absorbed by the atoms, booting them up from a low to high energy level. The researchers knew that the time period for all atoms to become excited was around 250ms, therefore by beaming a burst of laser light into their atomic midst, the number of atoms still in their lower ground state could be counted (excited atoms cannot absorb the incoming photons, therefore only the atoms in the lower, less excited state will be affected). Initially they only looked at 125ms, when around half the atoms should be excited. And they were! Then then increased the number of observations, looking four times in 250ms. They found something unexpected. With each successive observation, the atoms would ‘reset’ their energy levels; in effect, by increasing the number of observations the atoms would never reach the higher state. The watched pot never boiled! (For further reading, search for “The Quantum Zeno Effect“).

The explanation here directly supports one of Schrodinger’s main requirements for the thought experiment. Quantum probability waves exist. What the researchers believe happens is that the probability wave of each atom is artificially collapsed by the act of observing. When the atoms are free from observation, the probability wave is free to spread out, increasingly the likelihood of observing all the atoms similarly excited. By looking multiple times, the wave is collapsed prematurely, preventing the wave from spreading out to its potential equilibrium state. In effect, the intent of the observer controls to outcome. If you want half the atoms to become excited, no problem, look at time t/2. You want the pot to never boil? OK, just keep watching continuously.

However, Shrodinger’s second and third requirements denoting the features of the observer doing the collapsing are not so easy to support. Why are humans so arrogant to believe that there is something inherently special about us that we are required for the universe to exist? It simply makes no sense whatsoever that outside of our measly existence, nothing is actually real until we look. Rather, the quantum constituents may be probabilistic however the virtual seething mass of particles that zip around and interact with each other must surely provide the means to collapse wave functions. A conscious observer is not needed for reality to have any objective meaning (what about prior to the evolution of conscious beings – are we all being observed by an omnipotent being which makes us all real?) The universe itself must surely be doing the observing and the collapsing, through the myriad of interacting particles.

I believe the main problems people suffer from when discussing quantum mechanics is that they try to relate it to pre-existing notions of reality. They also place the importance of human consciousness above the fact that the universe will continue to exist regardless of whether we are around to watch. This deluded geocentricism has long plagued humanity, causing major scientific retardation throughout the ages (Aristotle et al). The implications of quantum mechanics on reality still holds many mysteries. If watching a quantum pot causes it to freeze in its initial state, what does this mean for reality and intent (and also free-will)? If quantum processes control the operation of minds, perhaps it will also prove to be the mysterious bridge that spans between Cartesian mind/body duality. Perhaps the secret to consciousness is the uncertainty introduced by the quantum reality that underlies every physical process.