Time travel, could it ever be allowed?

[Tank]

As a thought experiment suppose a way of physically travelling in time were theorised and the various aspects of the theory were tested to the point where it was a 99% probability that one could make a working time machine that could travel backwards in time but not forward. You have the final word regarding whether the machine is built and tested or all the research is destroyed.

Would you build and test it or not?

[no_god_know_peace]

I would tottaly build it ! That would be a technological breakthrough to do something like that and it would be really cool to expierience time travel. I know that I would have to think of the possible consequences to building a time machine but I think my curiousity would overide it 

[DeterminedJuliet]

If it is possible, someone will figure out how to use the technology one way or another.

I would allow the technology to exist and work very hard to set strict standards as to how it's used.

It'd also be super cool! I'm currently re-watching heroes and I love Hiro's ability 

[OldGit]

The implications are staggering.

Don't go back and shoot your own grandfather - you'll cease ever to have existed.  So you never went back and shot him. So you do exist, after all.....  Reality starts to oscillate between two states.   Bang (?)

It's really worth reading a short story on the subject by Robert Heinlein, called All You Zombies, in which a man manages - after a sex-change - to seduce his own mother, thus becoming his own father.

I'd just settle for memorising the lottery results after a particularly big prize, then going back about 26 hours and buying a winner.  I couldn't be bothered with stocks and shares, they're boring.

[Ecurb Noselrub]

The implications are staggering.

Don't go back and shoot your own grandfather - you'll cease ever to have existed.  So you never went back and shot him. So you do exist, after all.....  Reality starts to oscillate between two states.   Bang (?)

I don't think you could change what has already happened, or even interact with the past - just observe it. On the other hand, if you could interact, you wouldn't change this present reality, but perhaps you would open up an alternate reality in another dimension. Just a thought. In any event, I would build it, and sell one-way tickets.  It might be a good way to get rid of some people, as well as helping my bottom-line.

[Pharaoh Cat]

I don't think you could change what has already happened, or even interact with the past - just observe it.

If we in fact were able to interact with the past, I would want us to resist that impulse.  But hey, when we get to the point that we can build a time machine, we'll probably be able to build some other cool stuff too, like a space satellite so powerful it can see faces and hear voices from orbit.  What I would do, then, is send the space satellite back in time.  Let it record sights and sounds from a safe distance and then return to us.  Oh - but can it return to us?  The OP said travel to the future was disallowed.  From the perspective of the past, today is the future. 

[Asmodean]

I'd build it, gather me an army of minions, a pile of antibiotic and antiviral drug recipies, a few cool weapons and other necessities and go back... Then try to set meself up as a king or some such and probably muck up the timeline completely, so that I eventually wouldn't even be born to travel back to time and just like that, we have us a gramps paradox... OR an alternate reality, in which case His Infernal Majesty Asmodean would probably be able to get himself a throne and a crown and even keep it.

[xSilverPhinx]

Hmmm....if I went back in time and farted, would that cause a storm when I got back?

Whoop, did I say that out loud?  

If the grandfather paradox does have implications in our reality, then maybe you wouldn't have to do something as drastic to change things a bit.

As for time, if past, present and future exist simultaneously, then wouldn't it be physically possible to travel to the past?  

[xSilverPhinx]

I'd build it, gather me an army of minions, a pile of antibiotic and antiviral drug recipies, a few cool weapons and other necessities and go back... Then try to set meself up as a king or some such and probably muck up the timeline completely, so that I eventually wouldn't even be born to travel back to time and just like that, we have us a gramps paradox... OR an alternate reality, in which case His Infernal Majesty Asmodean would probably be able to get himself a throne and a crown and even keep it.

Oh dear. Then we'd be in trouble

[Asmodean]

Oh dear. Then we'd be in trouble

One could only imagine..! I would probably cause another mass extinction, but think of the FUN and the GLORY!  Would be worth it. Would do it without hesitation.

[The Magic Pudding]

My brain has no room for simultaneously existing alternate realities so I'll ignore the possibility.
It would be extremely difficult to time travel and not change the future.  
I think the tiniest change would result in the entire population be replaced by another.
So I have the option to travel back 500 years but by doing so I kill all my contemporaries and create a new set of people.
Although it pains me I will ignore other paradoxes.

A big rock is coming our way, extinction guaranteed, we've done the sums and ignored the big rock deniers.
I'm OK with sending an air craft carrier back 500 years, cruelly snuffing out other religions and setting us on a fast track to a high tech future/present.  Ideally we create a society capable of smiting the threatening rock, or at least I get to wear a fancy hat for a while.  Oh and anyone setting animals loose on unique island ecosystems gets handed over to Asmo for re-education.

[Tank]

So are UFOs actually time machines from our future?

Given the paradoxes inherent in time travel any time traveller would have to ensure that they had no material interaction with the past so flying around would be good. And of course the Roswell incident was simply a future human who screwed up?

[Pharaoh Cat]

So are UFOs actually time machines from our future?

Given the paradoxes inherent in time travel any time traveller would have to ensure that they had no material interaction with the past so flying around would be good. And of course the Roswell incident was simply a future human who screwed up?

Ooh!  I like that!  I never could see a reason for the UFO's to remain UFO's - but you've offered a really good one.

[xSilverPhinx]

So are UFOs actually time machines from our future?

Given the paradoxes inherent in time travel any time traveller would have to ensure that they had no material interaction with the past so flying around would be good. And of course the Roswell incident was simply a future human who screwed up?

Maybe, they always looked too humanoid to me.



I wouldn't build a time machine, or at least limit who could go to the past because I really do think that they'd mess things up and we'd find ourselves in a Back To The Future scenario, where he would always find a very different present each time he time travelled. Maybe alternate realities do exist, but who's to say if you go to the past, you'd be able to leave that particular reality and go back to yours?   

[Tank]

But what if there was a 1/100,000 possibility that the simple act of time travel would destroy the spacetime continuum and our entire universe would cease to exist the instant the machine was switched on?

Would you still do it?