Quantum Thoughts

Max Planck

Too Weird For Words!

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.

tree falls

“I’ve fallen & I can’t get up…”

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.

squirrel

Did you hear that?

And what about smaller animals? Do squirrels hear a falling tree? 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.

Schrödinger’s Cat

You may have heard of Schrödinger’s Cat. It’s a thought experiment created by Erwin Schrödinger to help illustrate the utter weirdness of 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.

cat in box

Hang on here… radioactivity and poison? WTF?!

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.

cat out of boxThis 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.

Heisenberg Uncertainty

You may have heard of the “Uncertainty Principle” — it’s been used in popular literature, for instance the “Heisenberg Compensators” supposedly used in the transporters in Star Trek.

transporters

Engage Heisenberg thingies!

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.

HUP

Werner’s actual Principle: The change in momentum (x) times the change in position (p) is equal-to or greater-than h-bar over two (a really tiny amount). As one gets bigger, the other has to get smaller.

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

light waves

Light waves

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.

light particles

Light particles

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.

About Wyrd Smythe

The canonical fool on the hill watching the sunset and the rotation of the planet and thinking what he imagines are large thoughts. View all posts by Wyrd Smythe

15 responses to “Quantum Thoughts

  • sonmicloud

    I enjoyed that post, some of which I was aware of, some of which I was not. Of course in another dimension I wrote it *smiles*

    – sonmi on the cloud

    • Wyrd Smythe

      I’m glad you enjoyed it (and welcome to the blog)! I want to live in the dimension where I’m married to Lucy Liu and I’m a successful Major League Baseball pitcher!

      • sonmicloud

        Thank you *curtsies*. I best not list what is going on in my favourite dimension, no-one has that much time *laughs* . It’s always nice to find another lover of words.

        – sonmi on the cloud.

      • Wyrd Smythe

        I do very much love wyrds, especially with meat! Even more I love the ideas they can express. We can’t think it unless we can put it into words. (Which is a big reason I think the growing illiteracy of today is so tragic.)

  • Lyla Michaels

    “Quantum effects, if they can be found in the brain, could allow for free will.” Woah! *Brain aneurysm* Hadn’t thought of that. Awesome.

    • Wyrd Smythe

      That’s a huge if at the moment. One description of the mind (not the brain) I read recently is that our conscious mind is a “standing wave” of unimaginable complexity. If that’s a reasonable description, it may be in the emergent properties of that wave that we’ll find some sort of quantum-level randomness.

      • Lyla Michaels

        A-mazing. I love it when things cross-over from one discipline to the next. Next thing we know, there’s a field of quantum neuroscience. Would you have the reference by any chance?

      • Wyrd Smythe

        You could start with the Wikipedia article, which will provide an overview, and go from there.

        Roger Penrose is a big proponent of quantum effects in the mind. His book, The Emperor’s New Mind was where I first ran into the idea. The book is a heavy read, and while he explores a variety of related and fascinating topics, he can only speculate about putative quantum effects in the brain.

        A more accessible book, albeit not about quantum effects, is Douglas Hofstadter’s I Am a Strange Loop. It’s actually a rewrite of his (in)famous G.E.B., which many ended up using as a weighty doorstop. The latter isn’t bad in any way… but at 777 pages it covers a lot of material.

        Hofstadter’s “strange loop” idea is similar to the “standing wave” idea I mentioned. He also has an interesting take on how our existence is smeared out across all those who know us and carry a piece of us in their minds.

      • Lyla Michaels

        Hmm. I’ll have to check these out. I currently have a couple on my nightstand (‘The Elegant Universe by Brian Greene and In Search of Schrodinger’s Cat by Gribbin). I’m trying to wrap my mind around String Theory as a ToE contender. I have to admit that sometimes I have issues with theories that are not experimentally verifiable- what’s to distinguish physics from philosophy at that point?

      • Wyrd Smythe

        The Gribbin book is very good, but a little dated. Mine is copyrighted 1984. On the other hand — other than String Theory — there hasn’t been a lot of new physics since, so it remains a useful text. (You won’t find much on quarks, though. Our understanding of them has improved a lot since the early 80s.)

        The Greene book is excellent (I can also recommend his 2nd book, The Fabric of the Cosmos — I haven’t read his 3rd or 4th, yet). You might keep in mind that Greene is a cheerleader for S/T, and after reading The Elegant Universe, you’ll probably be very enthused about it (I certainly was).

        You might want to read Lee Smolin’s The Trouble With Physics or Peter Woit’s Not Even Wrong for balance. (I highly recommend the Smolin book also for his take on science, in general, and, in particular, for the need for philosophy in science. See this blog article for a quote. I’ve talked to a number of scientist bloggers who seem to have no background in philosophy at all.)

        FWIW, in the same way physicists hate how the popular press refers to the Higgs boson as “the God particle,” most workers in S/T don’t much like the phrase “Theory of Everything,” because it’s misleading (“everything” really just means all of quantum physics + gravity). Plus, at the moment S/T is more a “theory of anything” (or worse, just a really interesting mathematics with no connection to reality).

        That said, S/T is kinda cool because it does unify General Relativity and quantum physics (and tosses in gravitons for free). One reason Smolin doesn’t like it is that he’s been been studying a competing theory, Loop Quantum Gravity, and feels that “S/T fever” has sucked the air out of the room.

        And then, as you say, when the physics is down at the Planck level, it may never be testable, and that does make it awfully speculative.

      • Lyla Michaels

        Yeah… I actually get annoyed at how much of a ‘cheerleader’ Greene is. I watched a documentary on String Theory he hosted and I always get very skeptical of people that seem too ‘partisan’ (for a lack of better words). With regards to the label ToE, I liked that Greene framed it more as a macro and micro universe explanation rather than classical/relativity and quantum mechanics “mending” (so-to-speak).

      • Wyrd Smythe

        Excellent; sounds like you’re going at this with clear eyes!

      • Lyla Michaels

        Science background education. ‘Can’t help it. *smirk*

      • Wyrd Smythe

        We’ll get along just great, then! 😀

%d bloggers like this: