>I think the confusion here is "in space", maybe you can expand on that. Is space itself not the medium? I think using that definition is fine! I tried to talk

>I think the confusion here is "in space", maybe you can expand on that. Is space itself not the medium? I think using that definition is fine! I tried to talk about things positioned in space directly instead of using a notion of medium because that word comes with a lot of imagery, and it can make discussion difficult, it's easy to talk past each other when we start using words that don't have a very well settled definition I was originally responding to a formulation where the medium is defined as something "present in a vacuum" that allows propagation of things. This is where imprecise language creates trouble, and why I don't like that word. You can say space is the medium, but you can't say space is a thing present in the vacuum that allows propagation. Vacuum is located in space, there's not a very meaningful sense in which space is a medium found within vacuum that helps things propagate, or at least that definition of the word is not very helpful to my understanding of the world For gravity, I'm okay with calling spacetime the medium, as long as you're careful to not imagine that there's some more ethereal thing within the vacuum that physics doesn't say anything about >But any medium is just the means by which something occurs or happens That's fine. That's not an invalid definition. I just think it's important to separate the concept of a physical medium from more philosophical notions that everything happens in a medium, even if that sometimes means defining the word medium as an immaterial concept whose existence makes people question the definition of the word "exist". In response to the original post, that definition of a medium inside the vacuum is something that doesn't exist. With your definition of space as the medium for gravity, you can make that work, as long as you can communicate what you really mean to other people when using that particular word!