The Casimir Effect

“Scientific revolutions are not made by scientists. They are declared post factum, often by philosophers and historians of science rather than by the scientists themselves.”

- Hendrik Casimir

What a strange ethereal plane I find myself in. Somewhat suspended above my own life, even above grief, which is some form of relief. This is incredibly alien; surely only the purity of youth can inhabit this state, swim in these pristine waters. Life, age, carries too many pollutants, the waters are muddy, strewn with debris, toxic algae and all manner of sticky viscous substances whose origins are vaguely familiar, but conveniently blurred from sharp memory. No one cares to trace the factory that dumped all that toxicity in their stream of life, you were right there, you watched it happen, but you don’t want to know about it. You just try and clean up the waters as best you can.

So what is this? What is this feeling? It tastes strangely metallic in the same way distilled water does, due to your taste buds not being used to the lack of impurities. It’s infuriatingly intoxicating. Infuriating because it doesn’t exist, it was never real. A perfect film script, written, directed and acted by me and by me alone. I was a runaway train; I yanked her arm and dragged her to a place she never meant to journey to. I thought for a minute we were travelling somewhere together. She was just too polite to ask me to stop and let her get off the train. Why didn’t she just stop me? How did I get it so wrong? It’s just too surreal to think I had imagined it all, she must have known something was building up. Can those layers upon layers have been so weightless? Maybe it was a brief moment of uncertainty, wondering how far I’d go. Perhaps just innocent curiosity, like a child dropping an ant in a cup of water with no genuinely cruel intent, only an anatomical interest in the ‘what happens’. Probably neither, just a distracted gesture without any real thought or motivation. Just the thousandth distracted gesture in a distracted day of a distracted life. A consciously numbed life, with a gaze fixed on a horizon that seems scorched and yet is the only possible focal point for her eyes. It was close. At least I thought we came close. I thought we were close, I felt we were close for a brief second. But there is a surely common misconception about the concept of closeness, that it is somehow a stable state of matter, an attractive force that makes the elements experiencing it stick or get closer still. That is not always the case, and the science behind it is compelling.

So many things about life rely on geometry. Allicin is the molecule in garlic that’s responsible for its smell. It’s a chiral molecule and our nose only smells it in one orientation, a simple geometric mirror image of the same molecule would be undetected by our olfactory receptors.

Geometry, what a curious operator, such an unsuspectingly powerful arbiter of reality. Geometry is also responsible for a very strange quantum mechanical phenomenon called the Casimir effect. It’s a very counterintuitive but measurably real phenomenon, it seems to be a force out of nothing, a force that exists from a position of closeness and a consequence of geometry. How painfully familiar that sounds.

Two concepts that are important to understand this phenomenon, the first one being the Heisenberg uncertainty principle, one of the pillars of quantum mechanics. One must take a deep breath before plunging to these subatomic depths, much like the deep sea, they are alien lands where strangeness is Queen and chance is the court jester. The Principle is this: even if the exact initial conditions of a system are known, at some future point the exact position and momentum of the system cannot be simultaneously determined with complete precision, because the act of observing such quantities would changes their reality. The concept same is true with regards to the energy of a system in any particular time interval.

Eq.1 Heisenberg energy-time uncertainty

There is an undeterminable amount of energy that may exist in an unfathomably small time interval. It is this playful dance of energy and time which gives rise to the phenomenon called ‘quantum fluctuations’, the second fundamental concept. Above the sea level, back in the world of humans, we are acutely aware of the wonderful creations than can arise when energy and time dance together. It’s no different down there in the deep sea really.

Quantum field theory is the theory that describes elementary particles, the tiniest building blocks of the universe. In this context, quantum fluctuations are essentially energy fluctuations in a quantum field and give rise dual particle/antiparticle pairs that form randomly from nothing and annihilate each other again all within a very short space of time. It is as if they ‘borrowed’ energy to exist and then immediately gave it back. Their dance having no real beginning or end, existing and vanishing in the randomness and uncertainty. It seems like a fanciful idea, but it is permissible due to the fact the energy at a given point is not fully determinable because of the uncertainty principle. Quantum fluctuations are a background hum of creation and destruction in the universe that is almost hard to believe, but it’s predicted consequences very much have measurable effects. The Casimir effect is one such occurrence.

Hypothesized by Dutch physicist Hendrik Casimir, the Casimir effect is a force experienced by two large conducting plates when they are placed at a miniscule distance from each other in a vacuum. The quantum fluctuations in the electromagnetic field interact with the conducting plates when they are at such small distances apart creating an imbalance between the field within the plates and the field outside of them. For two simple parallel plates that force is attractive, just like attractive is the force we normally expect human closeness should generate. However, the exact geometry and arrangement of the conducting plates in space is what determines whether the force will be one that attracts or repels. The same is true of human closeness, there are arrangements of the elements that can cause them to repel, not in spite of, but precisely because of the closeness. This unintuitive truth seems oddly self-evident, a contradiction I surrender to without complaint. We were perhaps just the wrong alignment, the wrong configuration of this unsuspecting, curious arbiter of life that is geometry.

I surrender to the truth without complaint, but not without regret, not without sadness, not without melancholy. This last one in particular scars the deepest. We both have a factory within us that produces bricks made of compressed melancholy, but we build fundamentally different structures with them. I build impossibly winding roads that don’t lead anywhere. With the same bricks she builds impossibly high walls that don’t let her go anywhere. I perhaps delight in the elaborate windings of my roads, but I’m left frustrated by the fact they lead nowhere. She’s perhaps frustrated by the feeling of being trapped within her walls, but delights in the comfort of protection they afford her from external agents. She isn’t the slightest bit interested in seeing where my roads go or how intricately I build them. I tried to break through her walls, but she only built them higher and stronger. There runs however a deep and silent kinship for the fact we are made of the same bricks. We don’t know each other’s structures in any detail, but we know what they are made of. That is an odd duality of closeness and distance, perhaps as odd as the duality of particles and antiparticles that fluctuate randomly in a vacuum. But the music has faded in the distance and the dance of energy and time, if it ever even existed at all, is a floating spectre too faint to even perceive. And all I am left with now is a quantum of uncertainty.