# Time is an illusion



## Warrior_98exp (Nov 26, 2021)

We can only move back in time not in future. 
Is that  ?


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## G.T. (Nov 26, 2021)

I believe the current science says travel into the future might be possible, we are doing it right now...in a way. As well as approaching speed of light stuff moving you into the future relatively, I'm no scientist though.

Thread title reminds me of Metallica song: The Small Hours


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## Venusian Broon (Nov 26, 2021)

G.T. said:


> ...travel into the future might be possible, we are doing it right now...in a way...


Well I'd be concerned if you weren't travelling forward in time, all the time. (Or at least that's my experience of the phenomena, I don't need to be a scientist to experience that )

I forget the tribe or group of people that have this view but I like their analogy: that we are 'travelling forwards in time' but doing so 'walking backwards' so that we only see where you have been!

Most of the standard laws of physics though are clearly time-invariant. i.e. elementary particles don't "see" a distinction between going backwards or forwards in time.

However, there is one important concept, entropy, that we believe, as stated in the second law of thermodynamics, can only ever stay the same or increase _over time_. Thus any system of particles/energy etc. starts at low entropy and ends up with higher entropy as time goes 'forward'. This gives time a clear direction as things start ordered and become disordered. (i.e. eggs break; but yolks, egg-white and shell do not leap together and form a perfect egg - or at least the _chances _of that happening as so astronomically high as to be essentially impossible.)

Why our univese does this...some link this to the expansion of the universe, because expansion allows 'mixing' therefore deep down this makes universal entropy increase. If the universe were to reverse this motion and start to contract perhaps the 'arrow of entropy' would also reverse and thus time would run backwards too? (Compared to what we experience now of course!)

Others speculate that different areas of the same universe can have different arrows of time (don't ask me how that works!) In such a universe beings living in a different time 'space' to us would see us moving 'backwards'. (Brian Aldiss's _Cryptozoic_ explores this, and other's works toy with some of these ideas such as PKD's _Counter-clock World.) _

Other theories of time can be _way_ wilder, of course. For example., one would suggest that our laws of nature and our experience of time are artefacts of a more profound and fundamental theory in a bizarre 'platonic' type of universe and are not special at all, thus to some extent "illusionary". At least compared to the fundamental reality of the universe.


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## CupofJoe (Nov 26, 2021)

> Time is an illusion. Lunchtime doubly so.


Douglas Adams, The Hitchhiker's Guide to the Galaxy


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## Harpo (Nov 26, 2021)

Eventually someday all the problems associated with time-travel will have been solved or ways around will have been found/made.

And thus, when the first working time machine gets invented, time travellers from the far future will immediately step out of it, bringing with them their highly advanced wristband versions (or whatever it’ll be) and within a few hours or so those will be everywhere. People will be startled at first but will quickly get used to the new reality. (Just as people once did with previous inventions such as trains, photography, planes, telephones, radio, internet, etc etc.)

I call it T-Day.


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## Venusian Broon (Nov 26, 2021)

Harpo said:


> Eventually someday all the problems associated with time-travel will have been solved or ways around will have been found/made.
> 
> And thus, when the first working time machine gets invented, time travellers from the far future will immediately step out of it, bringing with them their highly advanced wristband versions (or whatever it’ll be) and within a few hours or so those will be everywhere. People will be startled at first but will quickly get used to the new reality. (Just as people once did with previous inventions such as trains, photography, planes, telephones, radio, internet, etc etc.)
> 
> I call it T-Day.


Or it will be definitely proved impossible. 

I would call it noT-Day


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## Foxbat (Nov 26, 2021)

Walking backwards into the future……hmm, I like that

I once read someone joked (it might have been Asimov) that time was nature’s way of preventing everything from happening at once. 

Here’s where I get confused. Again, not sure, but it might have been Hawking who said that there was no time before the big bang. I just don’t get it. If there was no time and yet there was a big bang then surely (in my tiny mind) there had to be a ‘before’ - even if the before simply existed to allow the necessary energies to coalesce in a manner that facilitated the big bang.

Will I always be such a dunderhead? Only time can tell


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## Harpo (Nov 26, 2021)

Venusian Broon said:


> Or it will be definitely proved impossible.
> 
> I would call it noT-Day


I like to compare future time and past time. Let’s suppose the first working time-machine gets invented in 500 years, the early 26th century.
Now think back 500 years into the past, the early 16th century, and imagine people back then discussing possible inventions of the future (they won’t call them radio or internet or nuclear power stations, but you get the idea)

So yeah, it might never happen, and nobody reading this thread is a modern day Leonardo da Vinci.


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## Venusian Broon (Nov 26, 2021)

Foxbat said:


> Walking backwards into the future……hmm, I like that
> 
> I once read someone joked (it might have been Asimov) that time was nature’s way of preventing everything from happening at once.
> 
> ...


It's 'sorta' because the big bang theory is a model built out of Einstein's theory of General Relativity, which uses somerhing that we call space-time as a geometric building block. 

At time t=0, if we took these equations seriously there was no space-time (volume=0 at a singularity of infinite density), hence no time as we know it.

However that is a quite "literal" reading of the equations where one assume that singularities can exist. One could derive a cyclic model of an infinite in time universe that expands, sliows eventually, then contracts to a 'near singularity' and then bounces back. Of course how does one prove that such a situation has occurred? 

And more fundanentally General Relativity can not explain the microscopic - an area where Quantum mechanics is king. QM's view of time is objectively diffferent, it is somerhing external to space, whereas time is intrically linked to space in GR. 

And in near-singularities we'd expect QMs to be 'dominant rather than GR.

Thus our theories are both incomplete and we need a better 'theory of everything' that describes both the macro and micro  to really understand what on earth was happening at the very start of the big bang!


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## Wayne Mack (Nov 26, 2021)

I suggest that physics allows a type of time travel. It is known that time progresses at different rates and time moves more slowly in a gravity well. If one hangs out near a black hole for a while and returns to one's original location, then effectively that person has travelled forward in time. There is also time rate changes due to velocity close to the speed of light. Joe Haldeman's "Forever War" explores the latter in an interesting manner.

Both of these versions of time travel preserve matter and energy. Most time travel stories allow the matter to be removed from one point in time and inserted in another. There is a reduction in matter when the time traveler leaves and a gain in matter when the traveler arrives. This, to me, presents an  impossible hurdle to overcome for time machines that simply zap people between time periods.


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## worldofmutes (Nov 27, 2021)

Who was it that said time is a razor blade chopping away at itself?
It was John Updike.


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## BAYLOR (Nov 27, 2021)

Then there's   the grandfather paradox , in which if you went back in time and say prevented your grandfather from meeting you grandmother , you'd cease to exist but,  the problem is , if. you didn't then exist ,  how could you go back in time ? .  In Sprague de Camp's novel *Lest Darkness Fall  *written  in 1939,   handles this concept in a very interesting way.   The main character Martin Padway, a 20th century man gets sent back to 6th century Rome ,and, wonders if changing the past, would eliminate him from existence . Then , he concludes that in changing the past, he would not cease to exist but instead, simply create and alternate timeline . This has since become a widely used concept in alt history novels and stories.


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## paranoid marvin (Nov 27, 2021)

Time runs at different speeds in different places (and apparently in a black hole stops, or slows down to such an extent as to make no difference).
In such an eventuality you should be able to time travel forward, as you pop off to the black hole for a couple of hundred years, then (if possible) return to your starting point to find that you are 2 hundred years in the future.

Whether time can run forward or backward is immaterial, as I don't think that something that has happened can 'un-happen'. An icecube can melt, and can then be refrozen; but it can't not have melted in the first place. Otherwise we would have situations where our brains would remember something that has happened when it hadn't - and that would really mess things up!

As (I think) I've mentioned before, time travel into the past must be impossible, because if it wasn't then someone from the future would at some point have returned.


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## BAYLOR (Nov 27, 2021)

paranoid marvin said:


> Time runs at different speeds in different places (and apparently in a black hole stops, or slows down to such an extent as to make no difference).
> In such an eventuality you should be able to time travel forward, as you pop off to the black hole for a couple of hundred years, then (if possible) return to your starting point to find that you are 2 hundred years in the future.
> 
> Whether time can run forward or backward is immaterial, as I don't think that something that has happened can 'un-happen'. An icecube can melt, and can then be refrozen; but it can't not have melted in the first place. Otherwise we would have situations where our brains would remember something that has happened when it hadn't - and that would really mess things up!
> ...



If you travel to the past , you  end up creating an alternate branch in the timeline and  a new universe.  But in our timeline , we wouldn't be aware of this but , the versions of us in the alternate timeline  would be This is turn  would probably  create a whole host of time paradoxes and headaches for the people in the other timeline ,   but we wouldn't be effected here.


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## Harpo (Nov 27, 2021)

As I said, once the first time machine gets invented, from then on and forever after, time travel will be as ordinary and common as train travel currently is, with the temporal end-of-the-line being that first moment when the first machine gets switched on.
Currently we can’t go into the past, but after that moment, future people will be able to, but only as far back as that moment.


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## paranoid marvin (Nov 27, 2021)

BAYLOR said:


> If you travel to the past , you  end up creating an alternate branch in the timeline and  a new universe.  But in our timeline , we wouldn't be aware of this but , the versions of us in the alternate timeline  would be This is turn  would probably  create a whole host of time paradoxes and headaches fo the people in the other timeline ,   but we wouldn't be effected here.




Yes, this works well in a fantasy setting and allows for a level of believability in stories.

 I also liked Stephen King's take on it , when every time you return from the past to the present everything 'resets'. So whatever you did on your time travel is undone.  

In practical/scientific terms though, I think it's more likely that time travel isn't possible than that either of these things happen.

But who knows? We live in a universe which is possibility never ending; what is the relevance of time in an eternity?


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## paranoid marvin (Nov 27, 2021)

Harpo said:


> As I said, once the first time machine gets invented, from then on and forever after, time travel will be as ordinary and common as train travel currently is, with the temporal end-of-the-line being that first moment when the first machine gets switched on.
> Currently we can’t go into the past, but after that moment, future people will be able to, but only as far back as that moment.



Yes, I suppose this is possible. Have transporter 'pads' that can move you from one to another in both space and time. But there has to have been a 'pad' made at the other side to be able to make the journey.

It's entirely possible that in the near future with more and more powerful computers that even if we can't be transported back in 'real life' it can be done virtually. There's an episode of Black Mirror which deals with an eternal virtual existence.


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## Foxbat (Nov 27, 2021)

There was a SF story I read many years ago. From what I recall, it was about somebody who had had a sex change (although you didn’t know because that was the twist),  travelled back in time, bedded him/her self and subsequently gave birth to him/her self. It was quite confusing.


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## BAYLOR (Nov 27, 2021)

paranoid marvin said:


> Yes, I suppose this is possible. Have transporter 'pads' that can move you from one to another in both space and time. But there has to have been a 'pad' made at the other side to be able to make the journey.
> 
> It's entirely possible that in the near future with more and more powerful computers that even if we can't be transported back in 'real life' it can be done virtually. There's an episode of Black Mirror which deals with an eternal virtual existence.



Have you ever read the *Veils of Azlaroc *by Fred Saberhagen ? Its not specially a time time travel story but is has to do with time .   Azlaroc  orbits an usual star which ever year,  throws of  a quantum time veil.  if you happen to be on the surface of the planet when Veil Fall  happens, you can never leave because you become trapped in pocket if  time with everyone that happened to be on the planet with you, you can interact completely who them but with people stuck in earlier time pockets its become harder to hard to interact with them . You can talk to them and to large degree interact  with them but physically   can't touch them at all because there are in early time pocket  , they also  appear to be a bit faded  and you appear so to them. The earlier the time pocket the more progressive the fading becomes and it works both ways.


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## paranoid marvin (Nov 27, 2021)

BAYLOR said:


> Have you ever read the *Veils of Azlaroc *by Fred Saberhagen ? Its not specially a time time travel story but is has to do with time .   Azlaroc  orbits an usual star which ever year,  throws of  a quantum time veil.  if you happen to be on the surface of the planet when Veil Fall  happens, you can never leave because you become trapped in pocket if  time with everyone that happened to be on the planet with you, you can interact completely who them but with people stuck in earlier time pockets its become harder to hard to interact with them . You can talk to them and to large degree interact  with them but physically   can't touch them at all because there are in early time pocket  , they also  appear to be a bit faded  and you appear so to them. The earlier the time pocket the move progressive the fading becomes and that work both ways.




Sounds interesting.


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## Harpo (Nov 27, 2021)

paranoid marvin said:


> Yes, I suppose this is possible. Have transporter 'pads' that can move you from one to another in both space and time. But there has to have been a 'pad' made at the other side to be able to make the journey.
> 
> It's entirely possible that in the near future with more and more powerful computers that even if we can't be transported back in 'real life' it can be done virtually. There's an episode of Black Mirror which deals with an eternal virtual existence.


Or just the same pad, existing for N years. When it eventually stops operating / wears out, that time is known, and a new model is installed beside it, so that travellers can simply transfer like they do with trains or lifts.
But the important part (along with the original one getting invented) is that future versions will eventually be made much simpler, smaller, etc etc, and then quite cheaply massproduced. And those are the ones that’ll get taken back in time and given to anyone and everyone to use, just like Tim Berners Lee gave everyone the World Wide Web immediately.


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## BAYLOR (Nov 27, 2021)

paranoid marvin said:


> Sounds interesting.



Fred Saberhagen  was a terrific writer.


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## farntfar (Nov 27, 2021)

Foxbat said:


> There was a SF story I read many years ago. From what I recall, it was about somebody who had had a sex change (although you didn’t know because that was the twist), travelled back in time, bedded him/her self and subsequently gave birth to him/her self. It was quite confusing.


It's called "All you zombies", by Robert Heinlein.


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## farntfar (Nov 27, 2021)

paranoid marvin said:


> As (I think) I've mentioned before, time travel into the past must be impossible, because if it wasn't then someone from the future would at some point have returned.



This statement is like the Fermi paradox, and requires that the "visitor" from space or time allows themselves to be identified. 
As we know from endless Star Trek episodes (from all the series), it's terribly easy to disguise the fact that you're from the future, or from another planet.  All it requires is period dress and a woolly hat to cover your ears.


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## Harpo (Nov 27, 2021)

farntfar said:


> This statement is like the Fermi paradox, and requires that the "visitor" from space or time allows themselves to be identified.
> As we know from endless Star Trek episodes (from all the series), it's terribly easy to disguise the fact that you're from the future, or from another planet.  All it requires is period dress and a woolly hat to cover your ears.


In my version, the first time traveller would be the temporal equivalent of Neil Armstrong, globally famous where he came from. And closely followed by his agent, paparazzi, etc etc, and then those people bringing us all the eventual uberupgrade versions.
Pity the poor eccentric inventor, who doesn’t get much of a mention in all this (like the computer programmers who worked out all the essential numbers for getting Neil and co to the moon and back safely)


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## Wayne Mack (Nov 27, 2021)

BAYLOR said:


> Have you ever read the *Veils of Azlaroc *by Fred Saberhagen ?


Sounds sort of like the Legend of Brigadoon.


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## Astro Pen (Nov 27, 2021)

Time is the resolution of quantum probability. Countless quadrillions of them each second.
The 'now' is the point where probabilities resolve to one.
The past is immutable, now locked, singular, because of that, The future still an open book because those multiple quantum probabilities are still there.
How this impacts on free will, I will leave to the philosophers.


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