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Comment by bbor | Hacker News Reader

I’m not a physicist, but as an arrogant philosopher of science: isn’t it just field excitation? Like, every particle looks like a circle bouncing around a 2D piece of paper, but if you look reeaaaaally closely it’s just a localized 3D spike of energy in a usually 2D field of energy? So it’s made of the field/paper itself.

I must be under-thinking this, but that’s what’s worked pretty convincingly for me.

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So what is a field?

a thing that can have particle-like excitations

Historically, electrical and magnetic fields were discovered first. Then em-waves. Then photons.

This should tell us that fields are useful in their own right, without referencing particles.

A probability.

It’s everything! Idk, I don’t think the universe owes us an answer there. What is a human? Well, it’s a human. You can think of all sorts of mental tools for understanding humans (eg “species”), but ultimately they just are.

No... a field is mathematical representation. The universe is most definitely NOT made of fields.

Are you saying that the universe cannot be represented by mathematics?

I imagine you could use that argument to shoot down pretty much any explanation.

I'm saying that a mathematical representation of a physical phenomenon isn't the physical phenomenon.

Ok fair: they're things that right now are best understood using the term Field. I don't understand what kind of answer you're hoping for that would be better than this -- what kind of answer to "what is a particle" wouldn't be describable by mathematics?

By saying "the universe is fields", I'm saying "it's distributions of energy across spacetime". That's seemingly a consensus. Why demand that that energy must also form into strings or even tinier spheres or spheres in an alternate dimension or something? We have described fields in detail, I say Mission Accomplished

Let's say we describe a particle as being an excitation of a field. Can't we describe any physical phenomenon in the same way? For example, describe a football as an excitation of the football field. I think we all agree that this description does a terrible job of actually describing a football. In fact, I don't think it can be called a description at all. Likewise, I find describing a particle as an excitation of a field to be equally unsatisfactory.

A function that takes a point in space as input. The output can be various things, e.g. a scalar field gives a (possibly complex) number as output.

That's a bit too simple, not all functions work well as fields (differentiability is quite desirable) and you have no way to interact with the fields that way.

I think principal bundles come closest to what physicists call fields. Though I'm holding open the option that really the things in most equations are more like elements of the corresponding Lie-algebra.

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