I recently read this article which claims that last year’s LIGO observation of gravitational waves is proof that, at least on massive scales, there cannot be more than three spatial dimensions.
I don’t understand the physics fully, so could someone please explain this to me? I know it’s been theorized that gravity is relatively weak when compared to other forces because it leeches into other dimensions, and I think I understand how these observations disprove that, but how does this prove that there must be three and only three spatial dimensions?
Best Answer
I’m the lead author of the paper. Thanks for being interested in the work! Your question is a good one. Really, our work can’t say anything about extra spatial dimensions if they’re not doing anything to gravity or light. As you correctly mention, we can only constrain higher dimensions where gravity is actually leaking into them.
If there are higher dimensions, but our physics experiments can’t see or hear them, are they really there? :p (this isn’t to say there might not be other ways of detecting extra spatial dimensions — but really, if they aren’t affecting physics in any measurable way, there’s not much we can say)