Time Travel

I was reading about time travel this morning and came across a line on Wikipedia about how "Stephen Hawking once suggested that the absence of tourists from the future constitutes an argument against the existence of time travel."

And that got me wondering about time tourism. Of course, we'd have the gawkers and the other usual suspects coming to visit, but then wouldn't we also have the volunteers?

They'd have to come. I just can't imagine that philanthropical urge disappearing in people. I mean, if they still want to travel, why wouldn't there still be those who want to travel "with a purpose"?

And so they'd visit and sign on to help at our schools and out on the farm. Somewhere like California's Central Valley, maybe, where they could get the feel of authentic industrial mono-cultural agri-business.

But wait, wouldn't complete non-engagement be the only way time toursim could work? Otherwise, the time tourist might make changes in the past that could render them nonexistent. (Or whatever).

So all time tourists would have to remain completely out of sight. They couldn't even leave footprints. And no photos, of course. No interacting with the locals. No showing the kids their 24th century technology and turning them green with envy. No packs of futurists tromping through town with their weightless future packs exposing us to their future culture (which would irreperably alter ours). No futurists coming to live with the family.

I wonder how they'd enforce all that.