I don't believe in time travel, but you have to admit that it has great story potential.
A lot of time travel stories have the practice heavily regulated for fear that someone might change the past and thereby alter the future. I prefer to imagine that safeguards will be in place and that time travel will become a safe and popular entertainment like amusement park rides are now.
People who elect to ride into America in 2014 will take blasters with them to protect them from Al Capone's gangsters. Capone died way before 2014 but only the A students will know that and besides, as long as they stay in their seats, nothing they do...even with lasers...will effect anything in our era.
The tracks will take their cars down suburban streets and into houses where they can see how people in 2014 lived. Even the most mundane things we do in our time will appear exotic and awe-inspiring to the time travelers. Of course they'll be invisible, so no one in our time will know they're being watched.
Everything will turn out fine as long as the cars keep moving and so long as no traveler attempts to get out or leave something behind.
The problem is that someone (above) always breaks the rules. Someone will find a way to get out of the car and mess with the people in our time.
Will they still be invisible after leaving the car? I don't think so. Of course, coming from the future they'll no doubt find ways to avoid being seen.
You could be walking down the street in 2014 never be aware that a mischievous future person was near-by.
If we're lucky the worst that will happen is a prank where some future person deliberately loses a 2014's set of keys.
But it could get worse. A girl might deliberately cause an accident just to see what happens when two gasoline cars collide.
"After all," she'll reason, "it's not as if I hurt two
real people. These people in 2014 are just shades. They lived their lives and passed away a long time ago. Why can't I have some fun with them?"
Hmmmm. The future had better figure out a way to prevent passengers from leaving the car. Of course a really determined person could still make trouble. They might be able to sneak an android into 2014, someone who could pass as a local but who still takes her orders from the future. It could get nasty.
Yikes!
