There are 18 subscribers. I'm not sure what volume of posts you are expecting.
If you are looking for Reddit volume, change your expectations. They have a 150k+ subscribers. Nearly 10,000,000% more users. Give it time, or even better, ask questions about physics.
Ok, it just seems that on Lemmy people are creating communities like they are staking a claim to a piece of ground. They put in the claim, it case they want it, and walk away.