Is Time Travel (going backwards) Possible?

[Nytmare]

I personally subscribe to the Many Worlds theory regarding time travel. Beyond that, my layman's view of things would make me suspect that true sci-fi-esque time travel isn't possible for anything other than elementary particles.

Why we think there’s a Multiverse, not just our Universe – Starts With A Bang

 

[Janx]

I personally subscribe to the Many Worlds theory regarding time travel. Beyond that, my layman's view of things would make me suspect that true sci-fi-esque time travel isn't possible for anything other than elementary particles.

Why we think there’s a Multiverse, not just our Universe – Starts With A Bang

I'm too lazy to read that, but it's probably the same as my "forked quantum reality" concept. basically, there's infinite distinct realities that represent each outcome of a random chance (does an electron go left or right = poof! 2 new quantum realities).

Michael Crichton's novel Timeline used this approach (then ignored it later).

The premise being, if you COULD travel back in time, you are in an alternate quantum reality from the original that you experieced/came from. So the original reality where you were not present from the future exists and YOU experienced that (or descended from it).

Now you travel back in time, and that creates a NEW quantum reality. the current YOU and the Chrono-Native inhabitants of this NEW quantum reality experience whatever it is you and they experience (like the fun of trying to kill/protect Hitler). Let's say you're successful.

To the Chrono-Natives, they experience a world where Hitler died at your hands. To you, assuming you stay there, you watch the world experience a different sequence of reactionary events to Hitler's death. But that doesn't erase your memory of your past experience (or time spent in history class) of your original Quantum reality. If you hang out long enough, you'll get to see if this Quantum Reality's version of you gets concieved and watch you grow up (or not, if it turns out your mom marries somebody who wouldn't have existed if the Holocaust happened).

This is how Quantum physics guys explain away the paradox of killing your grandpa before your dad was born.

The time traveller is the observer. He witnessed or descended from a timeline where his grandpa concieved his dad in his Quantum Reality of Origin.

Going back in time, isn't going back in the QR of Origin. It's shifting to a new QR set in the past. You whack Gramps in THAT QR. If you then hop to the future, you are moving back to your Origin QR or the future position of this new QR. You don't cease to be because YOU were born in your Origin QR, not this new one where an equivalent you doesn't get made.

By travelling back in time, you BECOME the initiating choice factor for a new Quantum Reality. because there's the original reality where you were NOT present in 1940 Berlin, and the new reality where you just appeared from nowhere in 1940 Berlin.

there's probably more sciency details, but that's my basic understanding of Quantum physics and multiple realities. A few sci-fi authors have played with this idea, like Crighton, and Neil Stephenson if I recall.

 

[delericho]

I'm too lazy to read that, but it's probably the same as my "forked quantum reality" concept. basically, there's infinite distinct realities that represent each outcome of a random chance (does an electron go left or right = poof! 2 new quantum realities).

The problem with that is that every single event (on a quantum level, no less) creates an entirely new universe - duplicating everything that exists. Where does all the energy come from?

I suppose it's possible that there could be a finite (and fixed) number of parallel timelines, constantly splitting from and converging with one another, in some sort of ball of wibbly-wobbly timey-wimey stuff. But that does seem rather unlikely.

 

[delericho]

I'm inclined to think that time travel is probably theoretically possible, but may not be technologically possible - it may require an impossible large power source, or a computer that is too powerful to build, or whatever.

In any event, Morrus is right - if we were ever to develop time travel, someone would almost certainly have gone back and killed Hitler. That suggests that either time travel is impossible, or at least that we'll never get there.

 

[Jhaelen]

In any event, Morrus is right - if we were ever to develop time travel, someone would almost certainly have gone back and killed Hitler. That suggests that either time travel is impossible, or at least that we'll never get there.

But how about being able to observe the past (i.e. without being able to change anything)?

Is there any argument against that being possible?

No matter if time-travel is possible or not, I certainly enjoy reading stories about it, most recently Connie Willis' 'Blackout/All-Clear' and Neal Stephenson's 'Anathem', two very different takes on the idea.

 

[Janx]

The problem with that is that every single event (on a quantum level, no less) creates an entirely new universe - duplicating everything that exists. Where does all the energy come from?

Beats me. Ask a physicist. Like [MENTION=177]Umbran[/MENTION].

It's also possible that we all confuse "create" with actual creation.

What if it would be more accurate that all matter exists in all states and all positions in the entire universe. Much like the idea that an atom from Julius Caesar is now a part of you. the different Quantum Realities are the defined states. So it's less creating, and more just shifting to a QR that already exists, which to a layman such as myself, might be described as "created".

That all gets pretty complicated. I think it's simpler to acknowledge that we haven't seen any evidence of massive time vandalism that Hitler would probably attract. Sure, it's possible one guy could pop back and cap him in a bunker and set it on fire, and nobody'd know the difference. But as the future expanded more people would get access and be jumping back to mess with Hitler further. And some point, there'd be a soup of time-jackers hopping in around Hitler to save him or kill him, and we all would notice that something unnatural was going on around this one dude as 2 parties with laser guns were battling it out.

 

[delericho]

But how about being able to observe the past (i.e. without being able to change anything)?

Is there any argument against that being possible?

Well, you'd probably need to insert some sort of sensor to pick up the light/sound/whatever that you wanted to observe. And if you can send a sensor back in time, why not anything else?

But we're rapidly getting beyond the point I'm comfortable talking about (while sober, at least), so I'll have to leave off with "I don't know".

 

[Thotas]

I have this hypothesis, that I'd love to talk to a qualified physicist/cosmologist about someday, regarding a possible explanation of the increasing rate of the expansion of the universe. If that idea of mine is even close to right, no travel back in time at all, no how, no way.

 

[Bullgrit]

Some traveller would get hit by a car, have his arrival witnessed, people sieze his gear and figure out its a time machine.

timeline violators are likely to be ahead of the curve compared to time cops.

If some time traveler screwed up and revealed time travel, another could just go back and fix it. We in the "now" would never know. Just like with the "Hitler wasn't killed" idea, it isn't proof against time travel.

You can't really say that time travel doesn't exist because things are as they are. Things could be as they are *because* of time travel.

Anyone see the Family Guy episode where Stewie and Brian go back in time (again), Brian screws up the timeline, and they keep having to go back further to stop themselves from stopping themselves from stopping themselves? Eventually there were a couple dozen Stewies and Brians in the yard stopping their previous selves.

Bullgrit

 

[Scott DeWar]

but then you create a paradox, which really screws things up worse.