In The Avengers, Loki the Norse God of Mischeif and his Chitauri alien army invade The Big Apple. But how were they able to do that? Well I'll tell you it certainly wasn't by cab. They traveled through space with the use of The Tesseract, a small cube with enough clean energy to sustain the whole planet, or destory it. But can space travel really occur? And does such thing like the Tesseract even exist?
Actually, scientists around the world are studying worm holes and how to travel through them. Einstien was the first person to theorize this type of travel. Adam Hadhazy wrote an article on worm holes and space travel. He said, "The solutions describe a "tube" through the four dimensions of space-time, potentially connecting two regions vast distances apart. Think of two dots on a sheet of paper that is then folded so the dots overlap. That overlap is your wormhole, and it could theoretically allow for the transfer of matter from dot A to dot B instantaneously, instead of traveling the normal, long way across the sheet." (http://www.livescience.com/33730-science-fiction-fact-wormhole-space-travel.html)
So can space travel be achieved? The answer lies in the future and how science evolves from generation to generation, innovating new ideas and challenging old ones.