Topic: Are there any limits?

[Crash]

Well it's certainly possible to manipulate time with gravity. Sending anything with mass as fast as light is less certain. I think in order to achieve FTL travel you would have to sidestep the problems of resistance and start playing with time as well.

[Alieo]

Here's another time travelling thought I've often had. This occurred to me somewhere around my early teens...

One of my favorite stars in the night sky is Sirius, the Dog Star, exactly what Sirius Satellite Radio is named after. It is a bright blue star seen in the night sky between October through February. It is 8.6 light years away. What's astonishing to me is that if you are looking at that star, you are looking at light that started travelling from that star all the way to this point in time. Just think, what were you doing with your life a little over 8 1/2 years ago? How many loved ones did you know were still alive 8 1/2 years ago?

The earth gives off light of it's own too, of course, as a reflection from our sun. So, somewhere out there, (beneath the pale moon light.... SORRY! LOL) SOMEWHERE out there, Earth's reflection is being broadcast somewhere in deep space. Somewhere out there, light shining on the Earth from November 22, 1963 is beaming further and further into space at the speed of light. If you could travel FASTER than the speed of light, you could eventually catch up to the light emitted from November 22, 1963 and beat it back to Earth BEFORE it was emitted, saving JFK from assassination!

[Matthew]

If you could travel FASTER than the speed of light, you could eventually catch up to the light emitted from November 22, 1963 and beat it back to Earth BEFORE it was emitted, saving JFK from assassination!

Um... no.

You should really read/watch some theoretical physics so you can at least stay within 50 miles of the way we understand things to be true. As far as we know, there simply is nothing beyond light speed. You don't magically start going back in time when you pass the speed of light. Beating the light back to earth? What?

[Scyphi]

You could theoretically beat the light to someplace like Sirius, and then watch the light come in at the same time as the JFK assassination, but you wouldn't really have time-traveled, so you couldn't do anything about it.

Furthermore, it's unknown if you can even alter history in any shape or form, due to the resulting paradoxes.

I had some really smart friends once that knew a lot about this subject, and one day they were discussing the subject of time travel while I listened. Most of it, admittedly, went over my head, but at one point they did agree that the only way they could think of that time travel would be possible, was if you were on a ship traveling at the speed of light, and had a wormhole open in the back of the ship that exited somewhere outside the ship. Due to the time distortion effects you get at traveling at the speed of light, you can exploit that to, theoretically, travel back in time, but you would only be able to travel back a few seconds to a minute, not really long enough to be worth it, and you wouldn't be able to go forward in time. Plus, to even try it, you'd have to first conquer the issues of achieving the speed of light and finding a means of proving the existence of wormholes and finding a way to create or control your own.

Also, given what I know and understand about theoretical physics, there are only a couple of ways I know of that could theoretically be possible to use to achieve FTL speeds, and that's either using hyperspace (where physics conveniently don't seem to apply) and wormholes/portals. And the former of those is more fictional than realistic, and the latter is still quite theoretical, not even known if it's possible.

[-<WillyP>-]

Well, the thing about theory, is that in theory anything is possible, especially if you don't know anything about what you are talking about.


And even if you could travel back in time, you would not be changing history, you would be history.
What I mean by this, let's use an example. Let's say on May 14, 2011, I traveled back in time to, lets say, February 17, 2010, and posted the following in the joke thread:

A big Texan stopped at a local restaurant following a day roaming
around in Mexico . While sipping his tequila, he noticed a sizzling,
scrumptious looking platter being served at the next table. Not only did it look good, the
smell was wonderful. He asked the waiter, "What is that you just
served?" The waiter replied, "Ah senor, you have excellent taste! Those are called Cojones
de Toro, bull's testicles from the bull fight this morning. A delicacy!"
The cowboy said, "What the heck, bring me an order." The waiter replied, "I am
so sorry senor. There is only one serving per day because there is only
one bull fight each morning. If you come early and place your order, we will be
sure to save you this delicacy." The next morning, the cowboy returned,
placed his order, and that evening was served the one and only special delicacy of
the day. After a few bites, inspecting his platter, he called to the
waiter and said, "These are delicious, but they are much, much smaller than the
ones I saw you serve yesterday." The waiter shrugged his shoulders and
replied, "Si, Senor. Sometimes the bull wins."

Now, to anyone viewing that thread after February 17, 2010, would see that post. It would not make the slightest difference whether I had gone back in time to post it, or i had just posted it the way that in fact I did. Someone view the thread on February 18, 2010 would not even know the difference. So, now someone is going to say, what if you went back to February 17, 2010 and stopped yourself from posting? The answer is the same... my going back in time is in the present, but my having arrived at February 17, 2010 is a part of history, it happened in the past, on February 17, 2010.  To someone viewing the forum on February 18, 2010, if I stopped me from posting there would be no post. History records what happened not what could or might happen. It wasn't history changed, as on February 17, 2010 it was the present time then. If you could time travel, as soon as you arrive at some time, you become part of that history, and anyone who saw you would see you as being in the present, and you would greet yourself and yourself would say, hey you look just like me but with a bad haircut and you would say to yourself, well, I am you, on May 14, 2011 you are going to go back in time to today to post some joke about some Texan on Planet Descent, oh, and by the way don't go to that new place on Broadway that's where I got this haircut.
And then yourself would say, bs, I don't believe in time travel but it is a good joke I think you should post it, hey, wait, how did you get my password? So then yourself changes his password, not believing you are really him. But it does not do any good, because you are him, and you remember the password you changed it to. However you do intend to take the advice about not going to the place on Broadway, but obviously you forgot or something because if you didn't how would you have gotten the bad haircut before you went back in time? It's part of History now.

[TechPro]

Oddly enough, I feel a little dizzy.

* TechPro blames WillyP

[Crash]

A current idea is that time travel would rely on both a sending and a receiving device. You would be pushing it to go back in time to before time travel was invented, therefore.

I suspect that in practical terms, only slowing and accelerating time will be doable.

[Alieo]

The exact "HOW-TO" parts of time travel, I am not sure about, but I love being theoretical and thinking about the effects.  That's very interesting Willy P... but it brings back to light the old paradox. If you went back in time and killed your grandfather, would you cease to exist? If not, where did you come from? (Maybe you're actually adopted! lol)

[Matthew]

That paradox is long-answered. The answer is that there are infinite realities, each reflecting various choices. By killing your grandfather, you create a new reality in which you never existed and you from another reality had always killed your grandfather. In effect, nothing changed because it had already happened.

[Kaiaatzl]

Hmm... that's one way to look at it...

My brother and I are writing a book where the implications of time travel turn out to be so bizzare that no one can understand their cause - except for intertemporal beings like the antagonist... and needless to say we can't explain it to the reader (I doubt the reader is an intertemporal being who'd understand it ).

But other people can travel through time if they're abducted by an intertemporal being - this happens several times, with... unexpected... consequences.

[NUMBERZero]

I think practical time travel wouldn't really be "time travel," but rather "dimensional travel." Just go to the dimension across the street where the year is 1963. Boom.

[Alieo]

A-HA! Dimensions... yet ANOTHER series of infinites. Which brings us back to the original topic question: "Are there any limits?" Short answer? No. You can go an infinite number of dimensions, an infinite amount of speed, even get infinitely closer without actually being there, but no, I believe there are no limits... unless you are doing 31 in a 30mph neighborhood, you damn right there are limits there! :-P

Edit: I just lived up to my signature! LOL

[Matthew]

 

[-<WillyP>-]

The exact "HOW-TO" parts of time travel, I am not sure about, but I love being theoretical and thinking about the effects.  That's very interesting Willy P... but it brings back to light the old paradox. If you went back in time and killed your grandfather, would you cease to exist? If not, where did you come from? (Maybe you're actually adopted! lol)

Did you even read what I wrote? Let's say your grandfather was killed in 1903, before you were born, before your father was born. You could not have done it, nor could you have gone back in time to do it, as you never existed. You don't 'cease to exist' as your grandfather never lived long enough to produce your father, you just never existed in the first place. How can you go back in time, if you were never born?

[Scyphi]

Exactly what I was going to point out. Another way to look at it in slightly simpler terms is if WillyP went back in time to tell himself to avoid getting that bad haircut. Assuming his past self agreed to do, the very act of not getting the bad hair cut alters time in such a way that it eliminates the need for the future you to go back in time in the first place. Thus the resulting paradox would pretty much undo whatever you went back in time to do and you're back at square one.

And this is only the tip of the iceberg when it comes to time travel. Most science-fiction waters down the complexities quite a bit, but when you REALLY start thinking about the potential issues of time travel, it gets REALLY complicated REALLY fast, so much so that you have to wonder if it's really worth the danger. Because there are dangers, especially from paradoxes. How do we know if space-time can even handle a paradox? For those of you who have seen the movie, remember how in Back To The Future II when Doc Brown goes on about how Jennifer meeting herself could create a paradox that could pretty much spell the end of the known universe? He wasn't joking, that is a very real possibility given what we know. How do we know time won't just destroy itself or something every time it encounters a paradox in the timeline, big or small? And the thing is, the only way to find out with what we know now about time travel is to actually try it, which would obviously be really dangerous for, well, everything, because even the act of going back in time say a minute could be enough to create a paradox that time may or may not even be able to withstand.

Some of these time travel theories are really more of explanations to counter this issue, like the infinite realities solution, but like time travel itself, it's all unproven theories.

As I see it, there are only really three possible outcomes to time travel. One is WillyP's explanation where any act of time travel becomes a part of history and thus pretty much eliminates most of the practicality of time travel. Two is the same thing, except the resulting paradoxes could have devastating and lasting undesirable consequences. And three is the infinite realities possibility, and then it's debatable if that's really time travel and not just simply jumping from reality to reality (which actually might be easier now that I think about it).

Anyway, some food for thought on the subject of time travel.