When we talk about the space, the first things that we think of are Black Holes, Nebulae, Dwarf Stars & much more. The fundamental similarities between the examples I just gave is, all of these are visible objects that we have discovered out in the space. But, what if I told you that we know that, there is something out there that is not visible even with our super high space tech but, we know for a fact that it exists? Well, that's kinda what Dark Matter is but, it is slightly more complicated than it seems.
Dark Matter & Its Weird Characteristics
The majority (about 85%) of the total gravity in the universe comes from some unknown object or matter which kinda has to exist as the source. But, it cannot be seen by the human eye or to be more specific, our space telescopes or cameras. So, we don't know what this matter actually is but, we do know that it exists and scientists believe that it has a mass. The reason why scientists are obsessed with the fact that it must be some kind of matter with a mass to it, is because that is the fundamental property of gravity. The science we know right now, doesn't have a logical explanation of gravity existing without mass. That's because everything we know that is the source or even affected by gravity has a mass to it.
So, when we talk about Dark Matter, we still don't know what is the exact thing we are talking about. But, we know that it exists & most of the gravity in the universe comes from it.
Why Can't We See Dark Matter?
There is no confirmed logical explanation on why we can't see Dark Matter but, feel it's existence. However, the possibilities are really interesting. Dark Matter can just be regular matter lying in higher than three or even four dimensions. So, our eyes or telescopes or cameras cannot see them. And if that is possible, there might be another universe out there lying in that same dimension. This is also possible for multiple dimensions. So, maybe when the day comes when we find out what Dark Matter really is, we may actually get a real Multiverse theory in our hands. Or maybe gravity exists without mass too but, we just haven't figured that out yet.
All of this seems really fun & interesting but, we still need to figure out Dark Matter completely. We still don't have the perfect answer to the questions like, "What does it look like?", "What is it's properties?", "Is it actually some kind of matter with a mass?" and many more. Whatever the situation is, Dark Matter is the proof of the fact that, we still don't know a lot about the universe. We will figure it out, eventually. But, until we get there, we are still in the dark from the greatest mysteries of the cosmos.