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Comment by brummm | Hacker News Reader

The article touches upon something that I think most people that learn about physics don't realize. The models physicists use to describe nature do NOT exist in reality. They are mere concepts that work well to describe natural phenomena.

My favourite example for this is the electron. Does an electron how we describe it in quantum mechanics exist in nature? The answer is no. The electron is a model construct we have made up that describes natural phenomena. Nothing more.

This is where non-experts that didn't study physics get confused when they read that an electron is a wave but also a particle. All of these concepts are just physical models that again do not exist in nature. But they describe different aspects of nature pretty well. And so we assign them a meaning beyond what the mathematical or physical model contains, a part of reality.

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The world that see you when looking out through your eyes doesn't exist in reality either. It's just models your brain puts together from some sensory stimuli (photons hitting your retina), but they aren't real, they are mere concepts that happen to work well enough that you may manage to live long enough to procreate... they were made by evolution, and evolution doesn't care if it's real so long as it works well enough.

I don't think it's meaningful to say that the electron described by QM doesn't exist in nature... something exists in nature and all we can ever do is describe it with a model.

>>> The article touches upon something that I think most people that learn about physics don't realize. The models physicists use to describe nature do NOT exist in reality. They are mere concepts that work well to describe natural phenomena.

Indeed, having completed a graduate degree in physics, by the time you've been introduced to a different model of the electron for the third or fourth time, it begins to sink in.

Physics isn't special in this regard, though. All conscious thought is about models, abstractions and filing things away in boxes. I might think this post of mine starts with the letter P, but if I made the http request by hand, starting it by sending the utf8 encoding of P to the network card won't work, because I need headers. On the other hand if my child tried to render the opening P I'd ask her to not draw on my phone screen please.

> Physics isn't special in this regard, though.

Yep. I immediately started thinking about how this “real”/“not real” dichotomy applies to programming. We write programs that confidently declare not only that they’re defining facts for the purpose of the computation, but transferring them and interoperating with other such stated facts. But they’re all abstractions, they’re all convenient fictions we use to describe, model and hopefully send electricity through minerals to achieve the result we defined.

Even stepping a bit away from the physics involved, just considering the humans who do lithography and are closest to reality, their mental model and work is still an approximation of that reality that’s effective at their level of abstraction.

And this doesn’t just apply to human-mechanics interaction. It’s something my messed up brain thinks about with human-human interactions all the time. We have mental models of how the electrical impulses travel through our fellow animated bags of meat, but they’re not just approximations they’re often very flawed. But we still interact and we hopefully don’t become overly obsessed with the underlying details we don’t and probably can’t fully grasp.

Physics is slightly special in that it tries to optimise for mathematical simplicity rather than ease-of-conscious-thought. If we find a simpler or more predictive model for the electron, physicists will happily abandon the model we currently have, while nothing will destroy our brain's model of 'what I type is what is sent'. Conscious thought isn't even required for the process of physics, we only use it because it is the only thing we have to approximate the mathematical reasoning that physics does require.

Definitely agree with your first sentence, I was thinking it's special somehow just not in the way we perceive models rather than 'reality'.

> The answer is no

Well technically I think the answer would he "We don't know" instead. We don't have anything better than the standard model - the perceived clash between wave and particle is resolved by a more general theoryz for example.

Yeah, that was just an example.

And to be fair, with regards to the standard model, we know the standard model is not fully correct and we still don't have anything better.

This all depends on your philosophy and definition of reality. When you get into stuff as far from everyday life as electrons, our intuitive definitions don't work very well.

Most scientists, I think, use some definitions along the lines of "Reality is whatever appears in our best models/explanations of our observations of the world".

If all observations of electrons we have ever made obey some law, we say that's the real behaviour of electrons. If we find out it doesn't always work, we realize reality is something more complex, and at some point hopefully we find out what it is.

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