(January 29, 2022 at 4:23 pm)vulcanlogician Wrote:(January 28, 2022 at 4:43 pm)polymath257 Wrote: I don't see a problem. Why would things have to be the same 'substance' in order to interact?
Well it does kinda depend on your definition of substance. But, as far as definitions of "substance" go, I like drawing the line at "must interact with physical reality."
You are pretty empirically-minded, Poly, so think about it. If there IS some kind of thing out there that doesn't interact with physical matter or energy at all, it may as well not exist. We'll never sense it. We'll never know it. And if we do somehow sense it or detect it- Boom. That's interaction.
It makes sense to define substance as something that MUST interact with physical matter or energy.
Interact is the keyword.
How does matter interact with matter?
An electron interacts with another electron or any other charged particle via its electric field/magnetic field.
A neutrino, a neutron, a photon does not interact with an electron via the electric force/magnetic force.
I think that neutrinos, a neutrons, a photons can all interact together via the their gravitation forces (if you want to accept that gravity is a force. There is another concept that sees gravity as a deformation of space. I think the electric force/magnetic force can also be viewed that way.).
There is a strong interaction between baryon particles, such as neutrons, protons, anti-neutrons, anti-protons. At close distances, they can bind together.
There is another force called the weak force. Neutrinos interact with other particles via the weak force.
So, it looks like all interactions are done via fields.
If one particle has field X and another particle has field Y, they will not interact with each other.
If one particle has field X and another particle has field Y and also field X, they will interact via field X.
So what Angrboda said makes sense.
