Well, I just stumbled upon this video on Youtube:

http://www.youtube.com/watch?v=EuGIsUY6ftc

Now there are explanations in the comments for this video, but I can't make sense out of them. I'm thinking you've got to be a genius to figure this out, maybe you don't, either way I am in pain trying to figure this out. Where did that mutha ficken space come from?

lol that's a puzzle?

Just move the green and tan together, and swap the triangle pieces lol

It's like moving blocks around.

EDIT: Oh you're supposed to explain WHY the space is there? Something to do with the different triangle lengths, not nerdy enough to give a specific answer lol

Alright Kev, so you're saying if I go and buy a sheet of graph paper, recreate the image and the shapes contained within, and swap them around like the video shows, I will end up with an empty space? I didn't know physics allowed that. But if I can't figure it out just by looking at it, it's going to bother the hell out of me enough to go and do exactly that.

I fail for jumping in and thinking I knew the answer lol, but I'm pro at rearranging shapes. ;D That's the easy part, but you're supposed to give some explanation of why the space is there with the same shapes, which is the tricky part lol.

Looking at the comments it seems that

the triangles aren't at the same angle (which you can see if you look closely) so it leaves a small space difference when you move them like that.

OK then. My mind is officially blown, and I am questioning the existence of factual scientific evidence as we know it, as well as the laws of physics, and space.

I just took a piece of paper, cut out an exact replica of the top figure, inner shapes and all, and rearranged them as shown. I was left, get this, with a ******* EMPTY SPACE. Where did that little square go? I have no idea, but I'm about to call it a day. I need some sleep or something, cause I must be dreaming.

Ok.

I seriously would like to meet the creator of this optical illusion and cut his balls off, soak him in a vat of gasoline, and while covered in gasoline, slowly skin him with a shaving razor (I would make sure to TAKE my TIME) then soak his skinned body in another coating of gasoline and maybe some salt for good measure, then make him sit and wait while I tell him how I'm going to burn his skinless, lack of testicles self.

U mad bro? Oh definitely.

Not that hard, one has the two pieces below the small triangle and the other one has them below the larger triangle.

if it were a crisp, thin line drawing on true graph paper, it would be glaring. i wouldn't even call it an optical illusion, more of a lack of focus.

The top box of the 2 non triangles is a 3 by 5 which means it has 15 squares, an odd number. The bottom box is an 8 by 2 which is 16, meaning there has to be a missing box to have the same area assuming the other 2 triangles are held constant.