Time Travel is impossible

Tychu · Post by **Tychu** » 2005-04-02 04:06am

I know its all a theory.....i mean i dont know anyone who went through time but if you really think about it Time Travel is impossible. I mean if you go in the past to change something it almost certantly will change how you came about..

meaning that if your history was changed you probally would have done things diffrently and you may not be going back in time, therefore what you just did in the past will be a paradox and the whole space time continuim will be destroyed and the universe will implode, so there it is imposible

Real You-----goes back in time------- blows up airplane factory-------- it was your grandfathers job-------- parents lived in diffrent place----- your not born but the factory is still destroyed but by a person that never existed!!!!! then the universe goes and implodes

dragon · Post by **dragon** » 2005-04-02 04:18am

Its called a temporal paradox and have been the discussion in numerous sci-fi shows as well as scientific journals. Even though alot of science point to existing alternate dimenisions. So maybe if you went and changed something all you did was create an alternate timeline in which you are stuck and can't get back to your own timeline. But then thats completely theortical as well and most likely impossible.

The Third Man · Post by **The Third Man** » 2005-04-02 07:51am

There are a few points I don't agree with. First, as addressed by dragon, you could get around the problem by theorising alternate timelines. That notwithstanding:

Your paradox only addresses time travel to the past, it doesn't say anything about going to the future. So you should really say "time travel to the past is impossible"

Why should the whole time-space continuum be destroyed, and a huge "implosion" occur just because of a little paradox? I think this is an bit of a leap in logic; the universe may be perfectly happy to carry on regardless of a paradox (so long as it doesn't notice

). And you haven't addressed the energy issues involved in instantly destroying the whole universe. Where would the implosion energy suddenly come from/go to? (Admittedly this energy thing could maybe in itself make an argument against the possibility of time travel to the past)

Lastly, I am not at all convinced that changing something in the past will instantly change the "present" or "future" - if I kill off my grandaddy back in the past, I don't see why I should fade away (a la Back to the Future) or instantly vanish in the "present".

Post by **NecronLord** » 2005-04-02 10:26am

Tychu wrote:I know its all a theory.....i mean i dont know anyone who went through time but if you really think about it Time Travel is impossible. I mean if you go in the past to change something it almost certantly will change how you came about..

meaning that if your history was changed you probally would have done things diffrently and you may not be going back in time, therefore what you just did in the past will be a paradox and the whole space time continuim will be destroyed and the universe will implode, so there it is imposible

Real You-----goes back in time------- blows up airplane factory-------- it was your grandfathers job-------- parents lived in diffrent place----- your not born but the factory is still destroyed but by a person that never existed!!!!! then the universe goes and implodes

And what if you only came about because of time travel. Say, hypothetical uber romans travel back in time to ensure their existance, finding recordings of their intervention?

McC · Post by **McC** » 2005-04-02 10:48am

My view of time travel is thus:

You cannot go back in time to kill your grandfather because you didn't. Your very existence proves that such an occurence never took place. Therefore, even if time travel is possible, it is predestined when you do the traveling that you will not affect (or have already affected) the change you wish to affect.

wolveraptor · Post by **wolveraptor** » 2005-04-02 10:53am

don't most theoretical physicists solve the paradox of time-travel through parrallel universes?

for example: you go back in time and kill old gramps. what you really did was travel to a parrallel universe that was at that stage in time and kill that grampa. There are an infinite number of parrallel universes, with an infinite number of gramps. you just killed one of them, and in that universe, you will never arise (unless you killed gramps after he already had your mom/dad).

time is viewed as linear here. this is your verse
--------------------------------------------------------------2005
this is gramp's verse
------------------------------------------------1905

as you can see, the universe you visited had not yet reached 2005 in its timeline. thus, you can alter it before it does by killing gramps.

needless to say, all of this is unprovable, but it does solve the paradox.

McC · Post by **McC** » 2005-04-02 11:10am

I think this idea used to be popular, but no longer is. There's no experimental evidence for it, nor does the math require it (IIRC).

Robert Walper · Post by **Robert Walper** » 2005-04-02 11:17am

Time travel is obvious and proven possible. We are currently "travelling" through time at one second per second. Depending on your location/altitude relative to gravity (warping space/time) sources (such as Earth), you may in fact be travelling slower or faster than others around you. However, the differences are so minor no one without extremely precise instruments would be able to tell.

McC · Post by **McC** » 2005-04-02 11:19am

...*slap*

Large displacements in time, Robert, large displacements. Affecting the rate at which we perceive time to pass isn't the same thing as instantaneously relocating to different points in time.

wolveraptor · Post by **wolveraptor** » 2005-04-02 11:21am

McC wrote:I think this idea used to be popular, but no longer is. There's no experimental evidence for it, nor does the math require it (IIRC).

Hmm. are they really saying that the paradox can be avoided without alternate verses? then what happens when you kill grandpa?

We are currently "travelling" through time at one second per second.

i knew someone would say it.

Robert Walper · Post by **Robert Walper** » 2005-04-02 11:23am

McC wrote:...*slap*

Large displacements in time, Robert, large displacements. Affecting the rate at which we perceive time to pass isn't the same thing as instantaneously relocating to different points in time.

I was addressing the false thread title.

McC · Post by **McC** » 2005-04-02 11:30am

unbeataBULL wrote:Hmm. are they really saying that the paradox can be avoided without alternate verses? then what happens when you kill grandpa?

Re-read my first post. You can't kill grandpa, because you never did. Invariably, even if you could relocate to a time to attempt to initiate this paradox, you will fail, because you already did fail.

Robert Walper · Post by **Robert Walper** » 2005-04-02 11:45am

McC wrote:
unbeataBULL wrote:Hmm. are they really saying that the paradox can be avoided without alternate verses? then what happens when you kill grandpa?
Re-read my first post. You can't kill grandpa, because you never did. Invariably, even if you could relocate to a time to attempt to initiate this paradox, you will fail, because you already did fail.

Well, there's two competing theories to explain time travel into the past. One is the mentioned alternate realities, the other is the concept that time travellers always were part of the past.

Chmee · Post by **Chmee** » 2005-04-02 11:52am

Well, on the whole issue of 'if you create a paradox the universe will blow up,' this seems to be a classic example of considering Earth to be the center of the universe, rather than a tiny speck of dust in an enormous cloud of dust. Maybe you could create a paradox so severe that Earth was destroyed, but in the universal scheme of things ... so what? (Every time we get a new report on some observed stellar phenomena that is putting out incredible amounts of energy from a small body, now you can think 'oh yeah, another failed time-travel experiment!')

There's also a question of how 'self-correcting' a timeline can be ... something that is completely a thought-experiment that we can't validate until ... well, until we can actually alter our place in the timeline forwards or backwards. But suppose you go back and kill grampa ... is the timeline elastic enough to compensate for this? Maybe the act of killing him changes things ... he was NEVER really your grampa, but grandma had a little secret that nobody ever knew about! You're really the milkman's grandson, and 'always' were ...

Icehawk · Post by **Icehawk** » 2005-04-02 03:27pm

The way I see it travelling back in time to your own past is an impossibility in the same way travelling at the speed of light is impossible. The universe and its physical workings simply make it impossible no matter what you do or what level of tech you have. Paradoxes are an impossiblility because the universe simply won't allow them to happen in the first place.

The only way for backwords time travel to work IMO would be to have it where the person going back isnt really going back at all. They are simply going into an alternate universe where the "local time" or whatever is in the past in relation to our own. That universe may be completely identical to our own but it is still completely separate and you will never influence your own universe in anyway by being there or doing anything.

wolveraptor · Post by **wolveraptor** » 2005-04-02 11:13pm

McC wrote:
unbeataBULL wrote:Hmm. are they really saying that the paradox can be avoided without alternate verses? then what happens when you kill grandpa?
Re-read my first post. You can't kill grandpa, because you never did. Invariably, even if you could relocate to a time to attempt to initiate this paradox, you will fail, because you already did fail.

Could you elaborate? For example, if you went back to kill gramps, had the revolvor in your hands, and had him in your sights, would a bird suddenly drop its load on you and screw you up, causing the missed bullet to zing past, alerting the cops to your presence, and forever denying you the chance to kill him?

Sharpshooter · Post by **Sharpshooter** » 2005-04-03 01:51am

unbeataBULL wrote:Could you elaborate? For example, if you went back to kill gramps, had the revolvor in your hands, and had him in your sights, would a bird suddenly drop its load on you and screw you up, causing the missed bullet to zing past, alerting the cops to your presence, and forever denying you the chance to kill him?

Look at it in this way: I discover time travel, and, being in financial need, go back two or three weeks into the past and give my past self the information. I (Past Sharpshooter) then goes and invests in all of the good deals, racking up several million dollars by the end of two or three weeks. Since I had no financial need, I thus would have not gone into the past with the information. Because of that, the inormation that led to my rise in wealth is never delivered, thus preventing said rise, and thus leaving me in the same condition as I was in before,

Sharpshooter · Post by **Sharpshooter** » 2005-04-03 01:53am

Stock infrmation, sorry. Where did that thought go, anyway...?

Deathstalker · Post by **Deathstalker** » 2005-04-03 03:00am

Sharpshooter wrote:Look at it in this way: I discover time travel, and, being in financial need, go back two or three weeks into the past and give my past self the information. I (Past Sharpshooter) then goes and invests in all of the good deals, racking up several million dollars by the end of two or three weeks. Since I had no financial need, I thus would have not gone into the past with the information. Because of that, the inormation that led to my rise in wealth is never delivered, thus preventing said rise, and thus leaving me in the same condition as I was in before,

What if you tell your past self, along with these stock tips, "YOU HAVE TO BUILD" the time machine. Your future self obviously has the plans, so your past self invests the stock tips AND builds the machine. I hate time travel, if messes with one's head!

Sharpshooter · Post by **Sharpshooter** » 2005-04-03 03:16am

Deathstalker wrote:What if you tell your past self, along with these stock tips, "YOU HAVE TO BUILD" the time machine. Your future self obviously has the plans, so your past self invests the stock tips AND builds the machine. I hate time travel, if messes with one's head!

Hmmm...

Wouldn't the second trip cause the first me and the second me to ppear in the same place at the same instant, thus causing immediete death, failure of communication, and everything else that leadsto it? That, or cause a possibly infinate number o copies of myself to appear one afternother, which has got to screw up things in some manner.

Queeb Salaron · Post by **Queeb Salaron** » 2005-04-03 03:21am

Deathstalker wrote:What if you tell your past self, along with these stock tips, "YOU HAVE TO BUILD" the time machine. Your future self obviously has the plans, so your past self invests the stock tips AND builds the machine. I hate time travel, if messes with one's head!

Then you've just created a past with an infinite number of yous!!

You are Person A. You build a time machine. You go back in time and buy stock, and then tell your past self - Person B - that he has to build a time machine.

Person B builds a time machine, and travels back in time. Person A continues to live into the future from this point. Meanwhile, person B travels back into time where he confronts another alternate self, Person C. Worse yet, B might go back to a place where both A and B (now C) were present, and there would be three instances of you IN THE ORIGINAL SCENARIO! At which point person B travels back into the past, and A and C continue to live into the future, along with another future instance of person A who is already living somewhere even further in the future than A (past) and C (formerly B).

pArAd0xx0rz!!!!!11111one1!!!eleven

Sharpshooter · Post by **Sharpshooter** » 2005-04-03 03:29am

You know, I was just thinking - technically, it might be possible to destroy one's self through the grandfather system (or anything remarkably similar, for that matter).

As has been said, you go back, kill gramps, wind up not existing, thus you don't kill gramps, thus you wind up existing. Doesn't this therefore place you in a permenant loop of cause and effect where you will exist to up until that point you travel back, but will afterwards cease to exist once the machine activates?

Queeb Salaron · Post by **Queeb Salaron** » 2005-04-03 03:35am

Sharpshooter wrote:You know, I was just thinking - technically, it might be possible to destroy one's self through the grandfather system (or anything remarkably similar, for that matter).

As has been said, you go back, kill gramps, wind up not existing, thus you don't kill gramps, thus you wind up existing. Doesn't this therefore place you in a permenant loop of cause and effect where you will exist to up until that point you travel back, but will afterwards cease to exist once the machine activates?

I dunno. Lemme go find out.
I dunno. Lemme go find out.
I dunno. Lemme go find out.
I dunno. Lemme go find out.
I dunno. Lemme go find out.

Hobot · Post by **Hobot** » 2005-04-03 08:26am

If you were able to travel backwards in time, wouldn't you also have to take into account where the earth was at the time you were traveling to? Not only is the earth orbiting the sun, the entire solar system is orbiting the galaxy, and the galaxy is busy speeding along as well. Even going back a few seconds could potentially lead to disastrous results.

Chris OFarrell · Post by **Chris OFarrell** » 2005-04-03 08:30am

Yup. Its something everyone overlooks. I think the general excuse is that somehow the mass most time travel ships are on or orbiting keeps a 'hold' pn them somehow. Hell its all I've got.

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