Something from Nothing

[Vertigo]

I think you might be right there Ursa although only after we have "passed" each other in time and we would then each be seeing each other's past selves. Arrrgh!

Actually I have always had an even bigger problem with time machines like that because they would have to be seriously smart, not just about time but space as well. In The Time Machine the machine dosen't move in space except when the Morlocks move the machine physcially and that gets accounted for by the machine landing up outside his house when he goes back. However here's my problem; in the intervening time the Earth has moved around the sun, the sun has moved around the galaxy and the galaxy itself has moved relative to the rest of the universe. A time machine would have to account for all of that as well (at least to be useful!).

RJM you are absolutely right about the time paradoxes, which in fact have always provided the strongest arguments about the impossibility of travelling back in time. You could not help but distort the future simply by breathing the air and converting some Oxygen ro Carbon Dioxide. It might seem like a minor thing but with chaos theory and the butterfly effect over the years that tiny tiny change would result in a slightly different universe.

[skeptical]

Interesting that this thread has morphed into time travel. Whatthehell!

Vertigo
If the modern concept that time and space are one is correct, then the movement through the galaxy is not an issue. If you move in time, and space/time is one, then you must move accordingly in space at the same time.

The best 'rationalisation' around time travel I have come across is the idea that, if you move back in time, you end up in a new universe. If you then 'return' to the present, it is not your original present. That way all paradoxes are ironed out.

Of course, all this is wild speculation. In science, empiricism rules.

[Vertigo]

You may have a point there Skeptical, it goes beyond my meagre knowledge of physics though and does seem counter-intuitive but then so much of modern physics is pretty counter-intutitive so maybe that's a good indication it is correct. That's getting kind of like one of those if he knows I know he knows.... sort of things isn't it!

And I just love the way some of these kinds of threads can morph through different areas

[Ursa major]

Just because one moves through time and space, that doesn't mean that there's any sort of coordination, let alone the complex one which has to take account of the movement of planets, stars, galaxies and galactic groups.

Apart from anything else, who or what provides that coordination? And if they exist, why can't they keep drivers, for instance, from drifting out of their lane on multi-lane roads (which is no more silly than keeping some random time machine in the correct spot on a planet and possibly a lot more useful)?

[woodsman]

Originally Posted by J-WO

Nothing will come of nothing.

-King Lear Act I, Scene I

I know this doesn't add to the discussion. I just wanted to look all cultured and stuff.

I'll second Vertigo - you do indeed look a higly cultured gent especially the hair.


Closer to the topic - I need a coffee before I attempt to re-read this thread and make sense of it all. I tend to think that time travel - at a macro level is impossible. Sending particles back in time though - I could maybe see that happening.

[Interference]

Oh dear oh dear oh dear, as someone's avatar might once have said ....

Time isn't really that mysterious. All of spacetime includes all of history, past and present. To go from one point in time to another is as easy as from one place to another. We just haven't figured out how to get onto that path yet.

Yes, Ursa, if time travel were as Wells described it, the traveller would appear, throughout his journey, to be moving incredibly, incredibly slowly. If, however, time is to be treated as a dimension (direction) it would be possible to step outside of this spacetime into time and back into spacetime again.

Simple, really.

[woodsman]

Originally Posted by Interference

Oh dear oh dear oh dear, as someone's avatar might once have said ....

I believe you may have taken a wrong turning sir, this is not that thread

Originally Posted by Interference

Time isn't really that mysterious. All of spacetime includes all of history, past and present.

I find that a bit oxymoronic all history is a little bit mysterious no?

[Interference]

LOL

I never even thought of that




Well, I've done a huge amount of thinking about this time thingummy, and sometimes it's so difficult say anything without saying everything that I end up saying nothing.

This links in with what I was saying about the Universe, how immensely huge it is in all directions, and how time is just one more of those directions (though I suspect it may actually be three more of those directions, but if I explain why I'll need another thread). So taking that tautologically huge vastness as read, Time becomes another direction, quite possibly away from space altogether.

The only evidence we have for time shows it moving in one direction only, from a past towards a future. But even saying it is moving is a bit tricky. We know we are aging, not getting younger, we know that things are decaying not repairing. So which is actually moving: Time or Us? (I'm still working on an answer to this one, sorry) From our evidence for one direction: Forwards; we extrapolate another: Backwards. Which is still only one dimension, isn't it? But how does one move in time? All we know is that we move with time in the direction it flows. But where is our evidence for that? In our memory. We recall a moment past, not one from the future (except in exceptional circumstances which would require yet another thread to discuss properly). So we accept, by consensus of experience, that we are moving forwards within, and with, time.

So there you have it: Time is a direction through which we have no control over our movement, have no evidence for (beyond common acceptance) and that governs the progress and ultimate fate of our existence. No mystery there

And every planet we can see, and every one we can't see (probably), is moving with us through this thing. So local time becomes irrelevant, anyway (so go ahead, kill your grandfather, the folk in Alpha Centauri won't mind in the least what kind of quirky, loopy mess you get yourself into).

When Dr Who says "this time anomaly will destroy the Universe" I think he's mostly over-stating the facts - possibly to make himself feel good about being twelve years old these days

So in saying that it isn't really all that mysterious what I mean is that, take the fiction out of it and the playful paradoxologisms and you end up with something extremely complex but really quite obvious. Time is. So is Left. So is Sound. So is the desire to drink more tea. Not mysterious, just darned annoying, sometimes

I'm not saying this is the whole story, you'll be pleased (I'm sure) to hear, but it is a portion of a fragment of a sliver of what works for me (so far).

Originally Posted by Vertigo

It might seem like a minor thing but with chaos theory and the butterfly effect over the years that tiny tiny change would result in a slightly different universe.

Very slightly, I think. However massively or minimally the planet might be affected, the (ahem) interference-wave would diminish to insignificance across the Universe as a whole.

[skeptical]

The time direction may be related to the Second Law of Thermodynamics. "Entropy tends to a maximum".

If time were reversed, energy would tend toward lower entropy. Disorder would move to order, which as far as we know, is breaking one of the most fundamental laws of physics.

[RJM Corbet]

But time doesn't exist, in an absolute sense. It walls the dimension of 'nature' that contains all we perceive. It is a sort of reference. There are beings that exists outside of and beyond the time#space dimension, who have outgrown it, so to speak? We call them gods, angels, whatever? (Heck Tate did start this thread with 'I don't know if this is science or philosophy' ...) Things are either growing or decaying, as Inter observes? There is no standstill in 'nature (by which I mean all that we can perceive with our 'natural' senses -- the whole perceiveable universe is part of 'nature'). There is no standstill in nature. If you're not moving forwards, you're sliding backwards. And we learn by bitter experience that it takes nine steps forward to make up for that one step backwards ...

[Ursa major]

Originally Posted by Interference

If, however, time is to be treated as a dimension (direction) it would be possible to step outside of this spacetime into time and back into spacetime again.

..because when we move through the other dimensions, we're always popping in and out or spacetime and cannot be observed other than at the starting point and the destination....

If time truly is a dimension like the others (give or take the unidirectional nature we seem to experienced), it has to operate like on:, i.e. to move from one point in time to another, we must pass through the intervening points. (This is one reason why I see time travel as fantasy, not SF: most time travel descriptions take on board that time is a dimension but then immediately throw away all the rules of movement along a dimension.)

[chrispenycate]

If time were reversed, energy would tend toward lower entropy. Disorder would move to order, which as far as we know, is breaking one of the most fundamental laws of physics.

The trouble with the laws of thermodynamics is that they are statistical. There is no actual theoretical reason why all the hot air molecules in this room shouldn’t congregate in one corner, freezing me and at the same time setting fire to the curtains. Certainly the chances of this occurring are minute, and we’d have to resort to nested exponentials to express the odds of it not happening, but in an infinite universe lasting for eternity it would occur an infinite number of times.

I agree this isn’t likely to give us reverse time (and the fact that mathematically an equation can be written allowing bidirectional or multispeed time prove nothing ; as Heinlein mentioned in “The number of the beast” a mathematician can write an equation describing anything {remember an eternally refilling picnic basket?} but just because it was mathematically consistent didn’t mean it had any relationship with “reality”, whatever that might be) but it could give us the beginning of the universe.

to move from one point in time to another, we must pass through the intervening points.

If you require to move. However travelling from point A to point Q without passing through the rest of the alphabet between can’t be rejected outright, even in spacial terms. There is some (not totally conclusive yet) evidence they are doing it in Geneva, already (no, nothing to do with CERN). No, I do not understand it yet.

[RJM Corbet]

I just imagine these great, interdimensional beings, viewing us like 3yr old kids in a nursery school, learning what we have to learn, contained by time, to protect us from outside forces we know nothing about, like little kids who wouldn't last half a day in the city before being hit by a bus or something ...

[Vertigo]

I think we are making a fundamental mistake in this thread with respect to our view of time. It is generally considered to be the 4th dimension (though sometimes the 5th) however to then attribute it the same sort of properties as the first three dimensions is unwise, unproven and almost certainly wrong. In other words to say that I can move back and forwards, left and right, and up and down in space does not necessarily mean I can do the same thing in time.

The term dimension has a specific mathematical meaning: "In mathematics the dimension of a space is roughly defined as the minimum number of coordinates needed to specify every point within it". A minimum of four coordinates are needed to specify every event in spacetime, so spacetime is a four-dimensional space. The fact one coordinate is different from the other three does not make it any less of a coordinate.

However time is fundamentally different to space as can be seen from the Minkowski metric: ds²=-c²dt²+dx²+dy²+dz². Time is still a dimension, but that minus sign definitely singles it out.

Einstein published his general relativity and Minkowski subsequently formalized the idea of four dimension spactime...Einstein adopted it...And physicsts spent the next twenty years slowly discovering what general relativity really means...

Without worrying about the meaning of the equation I think it is clear that time (t) is treated differently to space (x, y, z).

So to extrapolate how time should behave based on space would be incorrect. Also please remember that time is just a dimension. We talk about time passing but time does not move any more than 10 metres "moves" it is a measurement. You could say we move along the dimension of time just as we do other dimensions, but the dimensions themselves do not move.

[RJM Corbet]

Ok, if you're going to come with the equations, please explain the other factors? C is the speed of light? What is D? Thank you