Time Paradox!

[quatumrulesoverall]

A very interesting fact of Time Paradox, how our future, past, and presence are interlinked and correlated.

[Qfwfq]

But what exactly is your intention, in starting this thread? Without making an actual point, its hardly the way to start the kind of discussion we want in this forum.

[quatumrulesoverall]

When one reads Science Fiction there is hardly anything so fascinating and yet so frustrating as the 'Time Travel' story. Fascinating, because it often explores the question 'what would things have been like if...?" or "if one could change a small thing like the position of a grain of sand would that have large effects in the future?". These questions are at the heart of personal or historical regret. Suppose Hitler were never born. Would this be a better or worse world today? Would it be a different world 100 years from now or would the forces of history push towards a singular result?

 

The stories are often frustrating due in part to a vaguely spelled out theory of time which often allows events that are confusing, contradictory and paradoxical. A science fiction story should not leave us with more questions than it resolves. For a reader of Fantasy, this may be acceptable, for Fantasy is not supposed to be taken as explanatory, prophetic or possibly realistic. But a good science fiction story should have explanations that are not incoherent and if in the story there is something which is claimed to be impossible, then there should be an explanation for that also.

 

At the heart of the problem is the 'Time Travel paradox' which goes something like this. Suppose a person travels to a time before she was born and breaks a causal chain that led to the traveler's birth. This problem has been commonly explored by asking 'What if you killed your own grandmother before she first conceived?' (Curiously the problem is never expressed in terms of killing your own mother). The apparent paradox is then of a logical sort: P entails NOT P and NOT P entails P. If you kill your grandmother then you would not be born, which in turn would bring it about that you not travel into the past, thus you would not kill your grandmother, thus you would be born causing you to again travel into the past to kill your grandmother.... ad infinitum.

 

(Redirected from Time Travel and Paradox Click the link to read the full article.

I was so shocked by this concept and keep thinking why the people in the future still cant travel to the past...

[EStein]

... Suppose a person travels to a time before she was born.

 

Suppose that such a thing is impossible.

[Guest Lambus]

.

.

.

.

.

.

.

.

.

.

[sanctus]

Suppose that such a thing is impossible.

MAybe unlikely, prove it to be impossible....

[quatumrulesoverall]

@Estein: How would you know that is impossible?

@Lambus: the definition of paradox: A paradox is an apparently true statement or group of statements that leads to a contradiction or a situation which defies intuition. (Wikipedia). There is no straightforward definition for "reality".

@Sanctus: because you did not see it doesnt mean that it doesnt exist.

[EStein]

@Estein: How would you know that is impossible?

Did I say it was impossible? For sake of discussion, I said "Suppose that such a thing is impossible." In spite of the great movie, Back To The Future, the time arrow seems to have only one direction--forward. Personally, I think there's a better chance of a space alien giving a press confrence on the White House steps tomorrow than traveling back in time.

 

Here's a great little article from The Why Files called Trapped In Time.

...."Time is nature's way of keeping everything from happening all at once, as Woody Allen became famous for saying."

[Tormod]

A science fiction story should not leave us with more questions than it resolves....a good science fiction story should have explanations that are not incoherent and if in the story there is something which is claimed to be impossible, then there should be an explanation for that also.

 

Most good science fiction stories are simply stories set in a sci-fi environment. I see no reason to demand of science fiction writers that their physics be explained perfectly.

 

As long as their technology is consistent within the universe they describe, and as long as it is plausible, we should accept the poetic license that all writers have.

[CraigD]

IMHO, depictions of time travel paradoxes reached their fictional literary zenith in the following dialog from David X. Cohen’s “The Why of Fry”, episode #64 of the cartoon series “Futurama”:

Nibblonian: "It's a genetic abnormality which resulted when you went back in time and performed certain actions which made you your own grandfather."

Fry: "I did do the nasty in the pasty!"

Nibbler: "Verily. And that past nastification is what shields you from the brains. You are the last hope of the universe."

Fry: "So, I really am important? How I feel when I'm drunk is correct?"

Nibblonian 1: "Yes. Except the Dave Matthews Band doesn't rock."

Before, 2003, students of time travel science fiction could only refer to this scenario with uncatchy references to stories such as R. A. Heinlein’s 1959 short story “-All You Zombies-”, or thrown-off lines like “Temporal Parthenogenesis”. Now, thanks to Cohen, we can refer to the time travel paradox of being, rather than killing, one own grandfather by the catchy phrase “Past Nastification Paradox”. :) (although RAH’s AYZ paradox is an notch more complex than DXC’s TWOF).

 

In all seriousness, time travel and its paradoxes can be seriously considered, yielding some interesting conclusions and implications, but it’s a technically demanding pursuit. On of my favorites approaches to a study of some fundamentals involves a hypothetical, frictionless pool table, with perfectly elastic balls where a ball entering one pocket emerges from another with the same momentum some amount of time after or before it enters. It’s possible to calculate the position of any system of balls at any time on the table, though the calculation needs to be done iteratively, as balls from one position in time jump back to interfere with themselves or others from at an earlier time.

[Fifi Jane]

Hi

 

Just reading through some of the postings and now about to add my little bit...(at the risk of appearing to be a bit of a prune! As this is my first ever contribution other than saying 'hi')

 

Have been rather seduced with John Gribbins books on QuantumTheory but wondered why the conclusion I expected was never mentioned by him....I am given to understand that from a photons point of view, travelling as it does at light speed, that time does not exist from it's viewpoint - everything which presents itself to the photon appears to happen in the same instant...even if those events are light years apart....all to do with the slowing of time as one approaches 'C'....am I correct in thinking that at 'C' time ceases to exist?

 

If what I am given to understand is correct then what happens to the space in which such a photon is travelling? Does space exist for the photon? or merely to it's puzzled observer?

 

If all this seems a little naive (even silly) please be gentle with me as am a bag of nerves for finally making this contribution.

 

kindest regards Fifi.

[InfiniteNow]

I am given to understand that from a photons point of view, travelling as it does at light speed, that time does not exist from it's viewpoint - everything which presents itself to the photon appears to happen in the same instant...even if those events are light years apart....all to do with the slowing of time as one approaches 'C'....am I correct in thinking that at 'C' time ceases to exist?

Hello Fifi,

 

A while ago I asked a very similar question, and received some valuable and enlightening information from our members. You may find use in the thread below, and I encourage you to read it through. If, after exploring the existing dialogue, you still have questions, that would likely be the best place to pose them. Enjoy.

 

http://hypography.com/forums/astronomy-cosmology/6191-photons-have-no-time.html

[CraigD]

http://hypography.com/forums/newreply.php?do=newreply&p=172579

 

Welcome to hypography, Fifi Jane! Congratulations on a pretty deep first non-intro post.

I am given to understand that from a photons point of view, travelling as it does at light speed, that time does not exist from it's viewpoint - everything which presents itself to the photon appears to happen in the same instant...even if those events are light years apart....all to do with the slowing of time as one approaches 'C'....am I correct in thinking that at 'C' time ceases to exist?

Approaching it from the perspective of classical Newtonian mechanics + Special Relativity, and taking some liberties with the mathematics of limits, this is a reasonable conclusion.

 

A bit more precisely, one can say that, for an inertial frame with speed relative to another of exactly c (note that the symbol for the speed of light is traditionally lowercase, not uppercase “c”) the relationship between their clocks is indeterminate. If it were possible for a body A to travel at speed both c and zero relative to body B, and begin and end a trip near B, it would be impossible for any clock tA on A to predict the reading of a clock tB on B. Because the distance A travels as measured by B is simply [math]\Delta[/math]tB[math]\cdot[/math]c, this means that the distance xA traveled by A at speed c for any duration [math]\Delta[/math]tA can’t be determined. One might describe xA as “infinity”, but this doesn’t really change its indeterminate nature.

If what I am given to understand is correct then what happens to the space in which such a photon is travelling? Does space exist for the photon? or merely to it's puzzled observer?

Again from a classical+Special relativistic perspective, we predict that the photon “sees” space as contracted to a length of zero only in its direction of travel. In other words, it sees ordinary 3-dimensional space “flattened” to 2 dimensions.

 

Combining this length contraction, which predicts that space has length zero in A’s direction of travel, and the time dilation described previously, which predicts that xA = infinity, we’re faced with the question of the value of zero times infinity, another indeterminate quantity.

 

In short, the predictions of Special Relativity for bodies that move at both c and zero are nonsensical.

 

From a perspective of particle physics, objects that can move at both c and zero are prohibited. Also prohibited is any sort of clock – tA – that can be made out of photons. Photons (and other luxons - particles with speed c) are bosons, and bosons don’t interact with one another in a particle-like manner. So the idea of a photon being able to “have a viewpoint” is nonsensical.

 

One might object to the claim that photons can’t interact, on the grounds that they can, as a (superbly confirmed) prediction of General Relativity, interact via gravity. Gravity is not part of the Standard Model of particle physics, one of the great unresolved issues of physics. In principle, 2 photons emitted at exactly the same instant in exactly the same direction would oscillate with one another, making possible a clock (tA), and hence suggesting that A can “have a viewpoint”. However, the relativistic mass of such photons that allows this interaction to be predicted by General Relativity exists only relative to an observer (B) with speed c relative to the photons. Relative to one another, their speed is zero, so their relativistic mass and rest mass are identical, and zero. So this interaction can be used to make tA possible, of some ensemble of photons “have a viewpoint”.

 

In short, the interactions necessary for a body that move at both c and zero appear to do anything (sense, record, or otherwise have a viewpoint), and even the existence of an particles out of which such a body could be made, appears prohibited by particle physics. In some sense, photons can be said to exist “out of time and in reduced-dimensional space”, but this “existence” is so lacking in the qualities we take for granted of ordinary objects that we must carefully consider it to make sense out of what we’re saying.

[EStein]

..... as balls from one position in time jump back to interfere with themselves....

 

Again, the Nastification Paradox rears its ugly head.

[arkain101]

I dunno dude.. its a creation.. all the time.. but only now.. at least in our limitation I guess.. I think.. I dunno.. sure. :)

[EStein]

I dunno dude.. its a creation.. all the time.. but only now.. at least in our limitation I guess.. I think.. I dunno.. sure. :shrug:

Creation(procreation?) has been a bit diifficult, lately, as balls from one position in time jump back to interfere with themselves.:) I hate it when that happens. It's a nastification thing.

[arkain101]

Logic appears to break down when you look for limitation answers.

 

This would mean, trying to find a fundamental object. (which of course would have to be a mental contruct).

 

The rest of this post was off-topic.

 

I will post in page #3, to share some of my views on this subject of time and logic.