You don't actually have to do an experiment. You only have to make informative observations. Obviously we don't have multiple universes to compare across, but we think we know things about how far away stars are, etc.. Hossenfelder wouldn't disagree; she talks about science for which there are observations, but not experiments per se (in that you are powerless to impact the system).

If you can't even make informative observations (maybe with the aid of sophisticated technology), then it isn't science.