Thinking about thought experiments
3 Dec 2013 by Evoluted New Media
Niels Bohr, a quantum physics godfather if ever there was one, once said: "Anyone who is not shocked by quantum theory has not understood it."
He is of course correct. There are several central tenants to quantum mechanics – each easily written down in sentences of no more than a dozen words. One such sentence could read: All particles exhibit both wave and particle-like properties.
Simple to read, yet to really understand it – to really grasp its significance – well, that is altogether a rather different proposition. And that, of course, is because the quantum world is one that seems utterly counter intuitive to our own familiar, explainable, macro-world.
Our conscious mind has evolved to hold physical properties – at least those directly observable physical properties – as almost self-evident. How to move if you want to outrun a predator; how to strike an axe against the skull of your prey; how to judge where a thrown arrow will land. Key to our survival was the ability to form a mental map of our immediate environment and, in a basic way, derive how physical things interact.
Now, quantum physics demands that we throw off the shackles of our evolutionary past – that we enter a brave new world of imagination. A world where things are and aren’t at the same time. Where existence is a factor of probabilities, not absolutism. Where absolute truth seems embedded in the shifting sands of quantum phenomena.
Easier said than done. Yet many keen physicists have done so – none less so than the shimmering brilliance of Richard Feynman. It was he who first framed the ideas that quantum physics was beginning to uncover within a delightfully ‘simple’ experiment. Yet at the time he devised it, this experiment required no apparatus other than the cerebral deftness of a rigorous mind.
His thought experiment – the double-slit experiment – became the heart of quantum mechanics. It highlighted the tendency of an elementary particle to exhibit both wave and particle-like properties. And there is that ‘simple’ sentence again – yet its message was truly powerful with its full implications fundamentally shifting the way we view the universal laws of existence.
As technology advanced, thought experiment became hard evidence. And it really is quite incredible to think that even relatively large particles, molecules even, exhibit the same behaviour. Here we look at the latest demonstration of this – and witness the further exploration of the boundary between classical and quantum physics.
