Face to face with Schrodinger's Cat

Lent 2019: Day 4

I assume we're all familiar with the paradox of Schrodinger's cat - it's in a box, we don't know if it's dead or alive until we peek into the box to check. Let's look at this famous thought experiment in more detail. It is, after all, the easiest way to begin to understand the concept of quantum mechanics.

We all know that radioactive isotopes have half-lives. The half-life of Plutonium-238, for example, is 88 years, so after 88 years it is half as radioactive as it was. After another half-life of 88 years, a quarter of its original radioactivity has remained undecayed. Now, said Schrodinger. Take a single atom of any radioactive material. We don't know when it will decay. Taken en masse, the lump of the stuff will follow its half-life. But a single atom could decay now, tomorrow, in ten years' time, in a million years' time. Only the probability of its decay can be determined, based on its half-life. There is no cause - it will or it won't, we don't know when.

Back to the cat. A radioactive isotope will either decay or not. Should it decay, the radiation emitted will trigger a switch that will shatter a glass vial containing a poison gas. The cat dies. [Sounds cruel, but this was only ever a thought experiment.] Should the isotope not decay, there is no radioactivity to trigger the switch; the vial remains intact, the cat remains alive.

Now, Schrodinger thought of this thought experiment as a riposte to the Heisenberg Uncertainty Principle, which - in the case of the double-slit experiment I wrote about yesterday - states that unless an observer is present, we do not know whether a particle is acting as a wave or a particle. The presence of a conscious observer is crucial.

One answer to the paradox of Schrodinger's cat is the Copenhagen interpretation. Heisenberg and Bohr posited that unless - until - a quantum state is measured, it has no definite properties. So, according to the Copenhagen interpretation, the cat is both dead and alive until a conscious observer checks.

How can a cat be alive and dead at the same time?

Another answer lies in the Many-Worlds Interpretation (MWI). This posits that at the moment a quantum event happens, an entirely new universe is created, parallel to the one you and I are witnessing, but with a different outcome. According to the MWI, the cat is alive in one universe, and dead in another.

Is there enough room for an infinite number of universes, side by side, evolving away from each other as the result of infinite numbers of quantum events? The MWI has been around since before I was born, and has neither been proved or disproved, being just one of about five mainstream interpretations of quantum mechanics. Remember, that the basic physics behind quantum mechanics has been proven to eleven places after the decimal point, in thousands of labs around the world. The problem lies with interpreting it, understanding it philosophically. The science is sound and is the basis for nuclear energy, LEDs, semiconductors, magnetic resonance imaging and many more applications.

But what does it mean for us, for our worldview?

It's too big a jump to say that because we live in a universe governed by the laws of quantum physics, God exists or God doesn't exist. A lot of New Age claptrap has been churned out since the 1960s lazily leaning on the word 'quantum', as though it possesses mystical properties that can heal or enlighten.

Physicists are rightly cautious of having science hijacked by spiritualist cults, yet mankind today is further from believing that it has grasped the fundamentals of the universe than it was 80 years ago. There is more doubt, more questions. Cosmological questions, such as what preceded the Big Bang, the ultimate fate of the universe, the nature of dark matter and dark energy - and above all, the hard problem of consciousness. Did consciousness precede life? Is consciousness no more than the result of interaction between neurons in advanced brains?

I wrote a few months ago about Stuart Hameroff and Sir Roger Penrose's theory about orchestrated objective reduction (Orch-OR); I shall be returning to this as for me it is something that intuitively holds true, giving a scientific basis for many of my own ideas about consciousness, life and the universe.

For the time being, I shall leave you pondering the fate of Schrodinger's cat - and whether there is anything that you or I can do [within the framework of this thought experiment, obviously] to keep the cat alive?

This time four years ago:
Opening of Line 2 of Warsaw's Metro

This time six years ago:
A selfless faith

This time seven years ago:
Ul. Profesorska after the remont

This time eight years ago:
Lent kicks off again, for the 20th year in a row for me

This time nine years ago:
Half way through Lent

This time 11 years ago:
Spring much closer