Albert Einstein was the first to recognize that space and time are inextricably linked. This is called space time, and a mass, such as that of our Earth, influences space time. But nobody really knows what space time actually is, and the search for a subatomic particle that makes up space time is one of the biggest questions in physics. A team of researchers now has a super exciting answer. They say that space time is actually a fluid made up of tiny elementary particles. You could call it superfluid. This would mean that the cosmos is filled with an ocean of this invisible quantum fluid, and theoretically, it should be possible to measure this, because light would lose energy slightly when it shines through this superfluid. Unfortunately, our measurement methods are not yet good enough, but at some point we will certainly be able to test the superfluid hypothesis of which.