Marty has proof of time travel.

[bigdaddy]

Personally I'm fond of the theory that the time machine will never be invented. If it is invented, people will travel to the past and keep messing with the timeline. Eventually they'll change the timeline in such a way that the time machine never gets invented. Sooner or later, it always comes back to that.

I don't know how plausible this is, but I find it really amusing.

You can't go further back in time than when the time machine was invented. I like that theory I saw on "Into the Wormhole".

 

[Silvercrest]

How do you know? It's hard to speak definitively about a technology that's impossible.

 

[YellowSubmarine]

It's a speculation, but it would be a good reason why we don't have time travellers from the future in our century, which is one of the reasons some of us believe that time travel isn't possible. Another possible reason good is that it is very likely that time travel is expensive, most likely as expensive as interstellar travel, and you don't see time travellers for the same reason that you don't see aliens visiting us.

For example, one known way to travel through time is by travelling faster than light, and the energy required for that if it were possible seems to be enormous, you can actually go and calculate a lower bound using the first two laws of thermodynamics and it's really ridiculous AFAIR.

 

[doubleohfive]

It's a speculation, but it would be a good reason why we don't have time travellers from the future in our century, which is one of the reasons some of us believe that time travel isn't possible. Another possible reason good is that it is very likely that time travel is expensive, most likely as expensive as interstellar travel, and you don't see time travellers for the same reason that you don't see aliens visiting us.

That, or (assuming traveling back in time becomes possible someday) time travelers from the future are good enough at time travel to not get noticed. Notice that all I said was "good enough to not get noticed" because we have no way of knowing in this timeline if our history has changed due to temporal tampering.

For example, one known way to travel through time is by travelling faster than light, and the energy required for that if it were possible seems to be enormous, you can actually go and calculate a lower bound using the first two laws of thermodynamics and it's really ridiculous AFAIR.

True, but according to astronomy, this type of time travel only works in one direction. Science has yet to find a way to theoretically travel back in time.

 

[JarodRussell]

They all still have the video tape of Einstein's time travel.

 

[Mike Farley]

But then someone else will travel back in time a little further, get in line ahead of you, and end up being the one filing the very first patent. What do you do then?

Go back in time and kill his grandfather as a child. Screw that guy.

 

[Broccoli]

Clearly, the reason we don't have time travelers coming back is because the world is going to end next year.

 

[Scout101]

That, or (assuming traveling back in time becomes possible someday) time travelers from the future are good enough at time travel to not get noticed. Notice that all I said was "good enough to not get noticed" because we have no way of knowing in this timeline if our history has changed due to temporal tampering.

Doesn't seem possible. If it was one dude doing it once, then maybe. But once it exists, it would get used enough times, over long enough a period, that it would be impossible not to screw up. Someone accidentally dropping something, getting hurt/killed and leaving evidence, a disease (or immunity) that ends up out of sync, etc.

Might start off expensive/secretive/controlled/etc, but what about once it's been around a couple hundred years? Would be accessible eventually. Even if it were repressed for a while, it would pop up again sooner or later.

Think about it: not going to get an even distribution of travellers, and they're all going to want to see the 'big' events, right? At what point are there so many people wandering around Bethleham that there's nowhere for Jesus to actually be born? Would the Titanic sink because of the iceberg, or the 50k people that showed up to witness it? Wouldn't Crazy Horse turn the hell around if he saw that Custer appeared to have another 100k troops when he started his charge?

Pretty much the only argument you need that time travel (to the past) is impossible is that you don't already have proof that it exists. Even if we live in a 'boring' time that no one wants to visit, there'd be evidence of travellers from some other time in the past. Modern human bones in the Le Brea tar pits, or some such thing. Given enough trips through time, it's impossible to avoid.

Can't even play out a DTI or Timecop scenario where they clean up the mess, because every time the time traveller screws up, it changes the future instantly. The timecop now exists in a timeline where that screwup is part of history, and likely led to earlier investigation of possible time travel. Why would he want to travel back in time and try to delete his own history?

Not. Possible.

Ever

 

[Hartzilla2007]

Clearly, the reason we don't have time travelers coming back is because the world is going to end next year.

That or their too busy erasing each other from history so they can get the credit for inventing it.

 

[JarodRussell]

Clearly, the reason we don't have time travelers coming back is because the world is going to end next year.

Good point. What if there is no future?

 

[Silvercrest]

Obviously it means someone will invent a time machine and inadvertently wipe out the timeline.

 

[Broccoli]

Or we might just be stuck in a loop.

 

[Silvercrest]

Well, obviously the Mayans knew about it, so someone must have traveled back to tell them.

 

[Gaith]

What if there is no future?

What if there is no now?

 

[doubleohfive]

"There is no 'now' here."

 

[Skywalker]

What if there is no future?

What if there is no now?

Whoa. You just wrinkled my brain, man.

 

[RandyS]

But then someone else will travel back in time a little further, get in line ahead of you, and end up being the one filing the very first patent. What do you do then?

Go back a little further and pop a cap in his ass.

What else?

 

[Python Trek]

It's like the Liverpudlian physicist once said about black holes: "Thuh's no thuh thuh."

Time travel is about as possible as the existence of a supreme being..that is to say totally impossible.

 

[Photoman15]

Unless you have faith.

 

[Immolatus]

were all part of the Matrix anyway