I started with the idea of physical determinism and what it implies about free will and the future. Then I touched on chaos theory, which is sometimes raised as a possible way around determinism (short answer: nope). In the first article I drew a distinction between “classical” mechanics and quantum mechanics because only at the quantum level is there any sign of randomness in reality.
It turns out that the quantum world is decidedly weird, and while we have math and models that seem to describe it extremely well, it can honestly be said that no one actually understands it. This time I’ll tell you about some of that weirdness and how it may (or may not) apply to the world as we know it.
The key question here is whether our brains make use of quantum effects.
We can start with one of the weirder parts of quantum physics — the observer.
There is an old question about whether a tree falling in the forest makes a sound. It’s a silly question in that the answer is trivial once you actually define what it means to “make a sound.”
If sound is the physical vibrations (such as you feel when you touch a speaker playing music), then clearly a falling tree creates those vibrations and does “make a sound.”
On the other hand, if you define sound only as what we hear in our heads, if there is no head present to hear the sound, then — arguably — the tree makes no “sound.”
But what if there are some deer present? Deer react to sounds, so it seems they hear (better than we do, in fact). If deer are present to hear the falling tree, it’s hard to argue it doesn’t make a sound just because no people are around.
And what about smaller animals?
Do squirrels hear a falling tree (surely they must)?
How about insects? Do they quality as being able to validate the presence of sound?
At what point do we draw the line allowing the “hearing” of sound?
Something very similar happens in quantum physics.
The idea is that you have a cat locked in a box with a device that consists of a Geiger Counter, a radioactive source and a vial of poison. During the experiment, if the Geiger Counter detects a radioactive decay particle, it smashes the vial, releasing the poison and killing the cat.
Whether the radioactive sample decays (and releases a particle) is a random event. It is possible to know how many particles are released over time, but no way to predict whether one will be released in a specific time span.
Cruelty to cats aside, here’s where it gets weird:
According to quantum physics, since we don’t know what happens in the box (and because what happens is governed by quantum physics), until we actually open the box to find either a very angry cat or a dead one, the cat is dead and alive and an infinite number of states between dead and alive.
That’s preposterous, of course, and that was Erwin’s point.
We know the cat has to be either dead or alive and certainly not in some mystic quantum state between them (let alone an infinite number of such states).
At the classical level, things either are or are not, even if we can’t see them.
But at the quantum level, it works exactly that way. It’s only when we open the box and observe that things “collapse” into a specific state.
And further, which final state we find (dead or alive) is — for all intents and purposes — random.
This is what we mean by quantum randomness. The quantum world is undetermined until we look at it, and then — and only then — do things snap into focus as something specific.
There is nothing random about quantum physics up to that point (or after that point). The math that describes quantum physics is fully deterministic. But the world that math describes is in terms of probabilities.
Erwin’s Cat Box assumes the experiment is set up so that a radioactive decay has a 50% probability. That means the cat has a 50/50 chance until we open the box.
The Principle is due to Werner Heisenberg, and it expresses the minimum possible knowledge we can have about a particle’s speed (momentum) and position. Specifically, it states that the more we know about one, the less we can know about the other.
In fact, if we know one of those with absolute certainty, we can know almost nothing about the other.
The Principle extends to other pairs of properties. For example, space and energy are related this way. As we zero in on ever smaller chunks of space, the amount of energy in that chunk becomes more and more unknowable.
If the chunk is small enough (we’re talking several dozen decimal points of smallness), the energy can literally be anything. In fact, the energy can be so huge it can create a “Big Bang” and give birth to a universe. This is one theory about how we’re here — an infinitely tiny bit of space decided it had so much energy that it spawned a whole universe.
A popular misconception about the Heisenberg Uncertain Principle (HUP) is that it is a statement about our inability to measure accurately. This is — despite some college physics professors saying otherwise — wrong.
The HUP addresses fundamental limits of possible knowledge. At the quantum level, the universe really is, honest-to-god, no kidding, fuzzy.
(I find a certain level of comfort in that fact.)
We can measure a particle’s position to a high degree of accuracy, but in doing so, we surrender ever knowing its speed.
Or we can measure its speed and give up ever knowing exactly where it is.
Fuzzy Quantum Universe
On some level, the universe does not spell things out until we observe them, and even then, we are limited in what we can observe.
You may have heard that light is “a particle and a wave.” (More correctly, light has wave-like and particle-like properties.)
The kicker is that, if you observe light’s wave properties, its particle properties go away. And vice versa. Look for light’s particle-like properties, and — poof — it stops having wave-like ones.
To quote J.B.S. Haldane, “[T]he Universe is not only queerer than we suppose, but queerer than we can suppose.”
Down at the quantum level, reality is fuzzy and undetermined. Above that level, reality does appear to work like a machine and is (as far as we can tell) physically determined — nothing is random.
A key question is whether, and how, quantum effects affect the larger world. We don’t see that quantum fuzziness at the macro level. Quantum effects decohere at the macro, or classical mechanics, level.
Even chemistry is physically determined, so to the extent we’re bio-chemical machines, it would seem we are just big squishy clocks ticking out the minutes of predetermined lives.
Quantum computing — the next big thing — faces the challenge of avoiding decoherence long enough to do useful calculations. The challenge is a huge one, because a coherent state is extremely difficult to maintain (and I have certainly found that to be true, especially when beer is involved).
Do our brains somehow make use of quantum effects in consciousness? If so, that would provide an escape from the idea that every thought, every feeling, every action you take, was determined by past events.
Quantum effects, if they can be found in the brain, could allow for free will.
But so far there is no evidence that such exist. We are left truly wondering if our wondering is preordained in a script written long, long ago.