How do you square the following notions? a) dark matter does not interact with measurable matter b) proof of dark matter's existence derived by the measurable, relative, interaction of mass and energy
Regular matter interacts via the four forces: strong interaction, weak interaction, electromagnetism and gravity.
Strong interaction: binds fundamental particles together to make atoms. In every day terms, it’s what makes mass, mass.
Weak interaction and electromagnetism: causes radioactive decay and EM radiation (photons). In every day terms, it’s how we get light, radio, cell phones, etc. Also nuclear power.
Gravity: attraction of mass across great distances. It’s how we stick to the earth and why the earth circles the sun.
There are particles that don’t act through forces but are affected by them:
Photons don’t have mass so don’t cause gravity but are affected by it.
Neutrinos don’t have an electromagnetism effect so they can’t be seen at all only measured in very rare weak interactions.
Dark matter: No strong interaction so not a part of atoms. No EM interaction so we can’t see it blocking light. No weak interaction that we have observed. However they do cause gravity, so we can see that. All of the proofs of existence are via gravity and relate only to mass — we can’t observe any other properties.