Is time travel possible? It's still a matter of debate. If the universe behaves the way Einstein predicted, time travel may be impossible. But scientists in 2011 were surprised when they discovered neutrinos -- sub-atomic particles -- appeared to travel faster than the speed of light. While that may have been an error in measurement, if the neutrinos really did exceed the universal speed limit, time travel might just be a reality on a sub-atomic scale.
While the neuralizer from "Men in Black" would be handy for making folks forget the last few moments, what happens when you make a major mistake? That's when you hop into your handy-dandy time machine and risk introducing a paradox that could rip apart the very fabric of time and space in order to prevent yourself from an embarrassing situation. Sure, you might encounter a younger version of yourself or somehow set into motion a series of events that will prevent your own birth, but that's half the fun!
Time machines come in all shapes, sizes and styles. You could have a living creature that inhabits a multi-dimensional construct like the TARDIS in "Doctor Who." You might plop down on a comfy chair and manipulate dozens of levers and dials like the time machine in H.G. Wells's famous story. Or maybe you want to give that flux capacitor a real workout and zoom into time at 88 miles per hour (141.6 kilometers per hour) with the famous DeLorean from the "Back to the Future" films. No matter what your sense of personal style, there's a time machine out there for you.