Tony Stark and Bruce Banner, S.H.I.E.L.D's certified technoscientific geniuses, are examining the Tesseract. True to its name, it appears to be capable of manipulating spacetime in more than the usual 3+1 dimensions. That goes part of the way to explaining why it emanates a tetrahedron of warped space whose edges crackle with the blue light of energy rushing down some sort of hyperspatial gradient, but Bruce is still very surprised when it hits him.