the real time machine
Time machines may be possible, but the laws of physics will impose limits on what they'll be able to do.
When Simon Wells, the great-grandson of famed sci-fi author H.G. Wells, made the 2002 version of The Time Machine, he probably didn't know about Professor Ronald Mallet and just how close his story mirrored that of the film's protagonist. While the original Wells novel was fairly abstract, the 2002 version of the film created a back story for the unnamed Time Traveler. After losing his fiancee to a robber on the streets of London, he sets out to go back into the past and change what happened. Just like Professor Mallet decided to dedicate his life to building a time machine to go back in time and save his father from an early death. And neither machine can change what already happened.
There's something very interesting about how Mallet envisions his information travel machine working. If we were to send medical and scientific information into the past, wouldn't we start changing the timeline? Let's say that I use a time machine to send a note to myself in the past about catching the flu while visiting a friend. If I listen to my future self and skip on the visit, then why would I send anything to myself afterwards? The event I set out to stop didn't happen in the first place. This is the biggest problem with time machines. They break causality and we have little idea how the universe handles an attempted causality break. I wouldn't be surprised if the first time machine wouldn't work because there's some unknown force in the universe preventing the causality violation.
According to physicists, there's nothing out there preventing time travel. Create a wormhole large enough, step through it, and depending on the spin and direction of the other end, you might get spat out in the past or in the future. The big question is: then what? Every interaction in a timeline outside your own is a breeding ground for paradoxes that violate causality. On the one hand, physics allows us to travel through time. On the other, it doesn't want us to break causality. It's like a giant cosmic "do as I say, not as I do."
Clearly, there are a lot of things we need to figure out before we create the first time machines. Who knows what will come out of it and what will happen to whatever goes into it?
