Dead Cat Walking
Issue #27
Surely, you’ve heard about this famous cat?
It’s inside a box with an equal chance of being alive or dead. That means, till you open the box it’s both dead and alive.
It’s called Schrodinger’s cat, not because it was his, but because physicist Erwin Schrodinger came up with this famous thought experiment. Actually, his experiment consisted of an elaborate system that released poison, but let’s leave the messy details aside – and ask why this experiment was needed at all.
Well, in the early part of the twentieth century, a raging controversy was the particle/wave nature of matter. So, for example, were electrons particles or waves?
To the rest of us non-physicists this sounds absurd – clearly those teensy things are particles. The atomic model that many of us (ok, some of us) remember resembles the solar system with a sun-like nucleus and planets-like electrons, right?
So, from whence came this wave nonsense? Actually, it’s been around for . . . a few centuries.
In the 17th century, Christiaan Huygens (championing Team Wave) and Isaac Newton (repping Team Particle) clashed over light’s true nature. Sir Isaac’s Instagram Influencer-level status relegated the wave theory to obscurity.
Until – about a couple of centuries later experiments definitively established that light traveled in waves. Case closed.
Until again – a friendly uncle type named Einstein won the Nobel prize by essentially proving that light traveled in particles (photons).
This led to more theories, experiments and mustache-stroking, until Louis De Broglie established (and later won a Nobel for) the idea that all matter exhibited the wave-particle duality (not just light). ????
“Quantum mechanics” was the name given to this physics describing the subatomic particles displaying wave characteristics. But – in a sort of redux of the Huygens-Newton death match – there were two competing mathematical elucidations of quantum mechanics.
You may have heard of the first contestant, Werner Heisenberg. Yes, he of the Uncertainty Principle (which in the popular imagination is stretched to cover any dubious contradiction – such as, you can be a Buffalo Bills fan or win a Super Bowl, not both, because UP). The other was the aspiring feline assassin Erwin Schrodinger.
The problem was that their theories were utterly, terminally incompatible. Done and over with.
Until it wasn’t – when the genius John von Neumann (pronounced “Noiman”) decided to turn his million-watt intellect on it and developed an elegant synthesis.
Hallelujah, right? Not quite.
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It turned out that von Neumann had used some mathematical wizardry that implied that there was . . . no boundary between the quantum world and our physical world. The implication was that particles existed everywhere all at once as waves (called Superposition) but collapsed into a single position . . . only when observed.
Even friendly uncle Albert wasn’t friendly anymore, asking incredulously (insert exaggerated German accent) whether the moon existed only if there’s someone to see it. (May need to crosscheck that with uncle Albert’s official Twitter account @AlbertEinstein)
Erwin Schrodinger so disliked von Neumann’s take that he was willing to suspend a cat between life and death – actually, suspend it in both life and death – in his thought experiment to demonstrate its absurdity.
That’s the origin of the famous Schrodinger’s cat thought experiment.
And yet.
No boundary has surfaced to refute Von Neumann’s explanation (even though spooky stuff happens in the quantum world but not here). And quantum mechanics clearly works giving us valuable real-world applications like electron microscopes and GPS (and soon quantum computing – a topic for another day).
Schrodinger’s cat sounds as fictional as that other famous disappearing cat – but maybe not? ??
End Notes
Disclaimer – I’m not a physicist. If you are, please forgive my errors.
Interested in Von Neumann? Check out “The Man from the Future” by Ananyo Bhattacharya.
Interested in a wave-particle duality explanation? Check out:
Uncertainty Principle – Interestingly, Heisenberg used the lack of the commutative principle in matrix algebra to show that Position x Location is not the same as Location x Position. ?
#science , #insight , #learning , #physics , #vonneumann