After taking 1000ug LSD along with 10 grams of mushrooms, a fuckload of DMT, 500mg of weed edibles along with some nitrous oxide and morphine, I finally came to the conclusion that space-time is not flat but is curved.

I calculated the curvature of space. It is just so massive that we think space is flat. But we actually live in a gigantic spherical universe. We are like ants on the outside of a football. Inside the football is air.

Similarly, we are ants on the sphere known as the universe. "Inside" the sphere is what is known as dark energy.