The absence of visitors from future means time travel not possible?

That assumes that they find this particular time of interest or that they want their presence known. We may view our place in history as being eventful but who knows what will happen in the next 100,000 years. This could end up being a relatively dull period in human history. And even if they did come here, time travelers may decide to hide their true identity in order to avoid cultural shock and changing the time line. How would you know if the guy walking past you on the street is a time traveler if he didn't want you to know?

No visitors from the future possibly only proves that time travel to the past isn't possible. No visitors from the past just means that nobody has secretly invented a time machine yet.

Most likely if someone traveled into the past, anything he did would create an alternate future. Thus, a time traveler would probably keep a low profile. There's no way to know if time travel either backward or forward is possible with current technology. Michio Kaku theorizes time travel is possible, but who knows? I know I certainly would like it to be possible, but I have no idea if it is or not.

Requiescat in pace, Krystle Papile. I'll always miss you.

Actually if time travel into the past were possible, it would go a long way toward explaining the many-worlds concept in physics, which holds all potential outcomes exist in an endless series of parallel universes.

Requiescat in pace, Krystle Papile. I'll always miss you.

Larry Niven wrote an essay some years back, "The Theory and Practice of Time Travel" in which he pointed out that if time travel was possible, time travelers would keep monkeying with the past until they succeeded in making it impossible.

Who knows if we have been visited--it would have to stand to reason that any interaction with the past a time traveler had with events/people of the past would alter the future in some way. Smart time travlers would use the technology only for observation. It would have to be what Star Trek geeks call "the prime directive" to observe only, and I know that because I'm a Star Trek geek. Imagine if one day there could be a team of witnesses sent back to Dallas, Texas in 1963 to document the Kennedy assasination or London in the 1880s to try to identify Jack the Ripper.

I almost lost my life in a car wreck once, and I remember stopping to tie my shoe as I was getting into the car to drive. If I'd not spent those few seconds, the accident would never have happened.

A smart time traveler would have to take every step to avoid any interaction with the past because a few seconds of anyone's life one way or the other can make a huge difference, and who knows how that could ripple.

I was just re-reading the old Ray Bradbury story "A Sound of Thunder," and allowing any doofus to go back in time the way they did in the story would be an invitation to disaster. It's safe to assume it would be a government or university science/physics lab that would perfect the technology, and only trained professionals would be trusted to make the trip.

Ideally, the traveler(s) would be invisible and in sealed haz-mat type life support suits to avoid being seen or any microbes contaminating the past or future.

A time traveler could be sitting next to me as I type this and you as you read this, gathering info for his/her report on web geeks of the 21st century and their arguments on how many angels can dance on the head of a pin.

I'd like to back and watch Ruth hit a few homers and maybe catch Hendrix in a club. I'd file a full report of course.

Not necessarily, a lot of theoretical models of time travel state that time travel to a period before your time machine was built wouldn't be possible. So maybe the great time-travel era will open up at some time in the future.

time is a man-made concept, the past and future don't really exist, only the present..

this is you - this is me -