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Comment by esperent | Hacker News Reader

> When interpreting electrons as particles, the atom is mostly empty

The Bohr planetary model, which I assume is what you're referring to, is equivalent to Newtonian mechanics. It's simple to understand and a good starting point for high schoolers. It's even still usable for certain types of calculations.

However, like Newtonian mechanics, at a deeper level and according to modern understanding, it's fundamentally wrong.

Instead we use the Schrodinger electron-cloud model. According to which the ~nucleus~ (EDIT I mean atom not nucleus) is not mostly empty.

It's not pedantic to discuss this, any more than it's pedantic to discuss why Newtonian mechanics is less accurate than relativity.

https://www.compoundchem.com/2016/10/13/atomicmodels/

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> Instead we use the Schrodinger electron-cloud model. According to which the nucleus is not mostly empty.

The electron cloud and the nucleus are different things. The electron cloud on it's own is an empty volume except where the electrons are at any given moment.

>The electron cloud on it's own is an empty volume except where the electrons are at any given moment.

The article specifically rejects this way of thinking and makes the point that the electrons are not in the cloud. The electrons are the cloud. Thinking of them as little balls whizzing about so fast that it seems cloud-like is wrong.

Except saying that the volume of space is filled is also incorrect. Multiple particle’s probability distributions may overlap without those particles interacting with each other. They don’t “fill” space.

It’s common to say they behave as a particle and a wave, but it’s equally valid to say they don’t behave as a particle or a wave. It’s a distinct phenomena and thinking in terms of large scale things you’re familiar with is simply misleading.

Saying it behaves as a particle is wildly misleading, we should really remove it from the curriculum. If electrons ever behaved as particles or even if the wave function 'collapsed' into particles, they would immediately crash into the nucleus and the universe as we know it would cease to exist.

Quantized fields is a much better term. Also collapse of the wave function never happens, only increased entanglement.

Treating an electron as a particle is the most natural way to understand the operation of devices like an electron synchrotron or a cathode ray tube, though. Not helpful for atoms or molecules though, I agree.

I'm not sure about even the synchrotron, most people have the very incorrect perception that a single electron is being circled around rather than a continuous beam. This is so far from reality where we're doing something like 600 million collisions / second that I question the value of the analogy entirely.

The concept of a single particle as a point charge that isn't really interacting with everything around it is similarly flawed. We learn from a very young age to conceptualize that as the building block of matter, and entanglement as something weird. Instead it's the other way around: a single particle with a pure (unentangled) wavefunction is pretty near statistically impossible.

Particles unlike waves bounce off each other. For all the wavelike behavior in QM, bouncing just doesn’t fit.

It sounds like you might disagree that the room I'm in right now is filled with air or that my cup is full of tea.

This article is trying to help laypeople have better intuition about things from the quantum point of view. It's full of evocative prose. Arguing about the definition of the word "full" is completely tangential to the point.

More, I just think it’s misleading. Even the most basic introduction to physics should cover the idea that the air in the room has a pressure to it rather than the room being full.

The point of physics is to have a unified system where the same description applies to the widest possible number of phenomena. Calling atoms empty or full isn’t a great description but neutrino’s behavior for example lends itself to calling them empty.

And those clouds aren't in the 3d space, because if we consider an ekectron travelling from one galaxy to another, the electron-cloud will reach gakactic size before it interacts with something and then it will suddenly shrink into a tiny electron.

> where the electrons are at any given moment

That isn't entirely a thing.

Seems like you're argeeing with their point while framing it as if you don't agree?

They say the article is pedantry. I say that it's not. That sounds like a disagreement to me.

a probability field isn't really ever empty unless zero or near-zero is considered an empty space. which is kind of like a painting on which the some of the canvas is background

A probability field is not a geometric volume. The phrase "empty" is meaningless to apply to it and doesn't provide laymen with any useful intuition.

Fields may have high or low energy densities, and we might compare that to the height and frequency of waves on the ocean in explanation. But just as the ocean is violent or becalmed, not "full" or "empty", so are fields neither full or empty.

I assume that being probably empty is equivalent enough to being mostly empty, especially in bulk.

No, because as the article explains, the probability isn't of the "which pocket are my keys in" kind.

The pocket isn't empty because there is air inside...

national review told me to buy in bulk to achieve economic mobility so i think maybe you're right

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