Time.

[Farsight]

You mean you actually tried it?

 

http:\\http://www.relativityplus.info

[Fred56]

if the "where" refers to the original state of the system

 

it does, and this can only be “returned” to if the entropy change is zero. To use my travel metaphor, you would still have your ticket, and still be waiting for the "entropy train" to move.

 

You seem to be confusing the physical transfer of heat “back” into the system with the concept of “reverse entropy”. I'm referring to how entropy can't “run” backwards, and my metaphorical conjecture manages to confuse this, I see.

 

Interesting that we have banged this around this far without mentioning that engines use cycles to do work. Entropy, of course, can decrease during part of a cycle, but in the other part it increases so that, algebraically at least, the difference is zero. This isn't the same as saying entropy "goes" somewhere. It isn't some thing for a kick-off. Heat is a "thing" we can hold in our hands, though (but temperature isn't).

[Cap'n Refsmmat]

You mean you actually tried it?

 

http:\\http://www.relativityplus.info

 

I'd try if I didn't get a 403 Forbidden error.

[ydoaPs]

Sorry yourdad, but:

 

 

 

No. Heat can move around or be transported around a system, but entropy can't “go” anywhere. Perhaps you mean “heat” can “go back” into the system?

Welcome back to the Heat Engine. Entropy does decrease in a system with heat transfer out of the system. Think of it like this: Most commonly, entropy is defined as the amount of disorder in a system. Temperature is a measure of the average molecular kinetic energy of a substance. Heat transfer out of a system causes the temperature of the system to decrease(assuming no phase change is occurring). This means that after the heat transfer, the molecules are moving slower. Which is more orderly, fast randomly moving molecules or slow moving molecules? Even with a phase change, liquid molecules are more orderly than gas molecules; and solid molecules are more orderly still. That means that as you transfer heat out, you are getting rid of disorder as well.

 

 

 

But it is a one-way process, or change. Entropy is not reversible.

Yeah. You're right. My power plant doesn't work.

 

 

 

it does, and this can only be “returned” to if the entropy change is zero.

Not quite. It can only "return" if the NET change in entropy is zero. If entropy decreases, by the exact amount it increases, then the net result is no change. Just like if you walk forward 10m and then walk back 10m, you will be in the same place even though you walked 20m.

[Mr Skeptic]

I'd try if I didn't get a 403 Forbidden error.

 

It works now, I just got it. Might be time to start another Farsight thread Preliminary scan shows very few equations (but he does have some). I don't care about the equations if the description is accurate and precise enough to construct them ourselves, but I only scanned it so far.

[Farsight]

Please do. I'll be only too happy to discuss it. But do sit down and read the paper first, and raise relevant points. Hopefully Captain will ensure that good order is maintained. Best check with him first though.

[Cap'n Refsmmat]

It'd be best to start a new thread to discuss Farsight's paper.

[Mr Skeptic]

It'd be best to start a new thread to discuss Farsight's paper.

 

Yes, otherwise discussion will occur anyhow on several threads. However, I don't believe it will be any more productive than previously.

 

Um, getting back on topic... Maybe time is like matrix multiplication.

[Fred56]

Um, getting back on topic... Maybe time is like matrix multiplication.

 

You mean there's some connection? Or you mean we should ask Keanu?

[Edtharan]

We know that Space is expanding, What if the Flow of Time is due to the fact that Space/Time is expanding.

[Mr Skeptic]

Um, getting back on topic... Maybe time is like matrix multiplication.

You mean there's some connection? Or you mean we should ask Keanu?

 

I was thinking in terms of a transformation matrix, and certain properties of matrix multiplication.

[sovit]

if time travel back to past was impossible, how did ppl see UFO's?

[ydoaPs]

if time travel back to past was impossible, how did ppl see UFO's?

Stealth fighter tests in the '50's.

[Fred56]

I was thinking in terms of a transformation matrix, and certain properties of matrix multiplication.

What might this transformation matrix look like? And what are these certain properties?

[Fred56]

if you walk forward 10m and then walk back 10m, you will be in the same [/b']place even though you walked 20m.

You won't be in the same place, though --because the surface of the planet is in constant motion. Also you would burn up resources walking around --you can't "walk backwards".

[Eric 5]

One can time travel to many unpredictable futures. Picture if one was at a crossroads of life, trying to pick between two careers, or two possible mates. Depending on one choices, one would create different future for themsevles. Often one may not know which is the better choice, or what might have been, but both choices will lead to a different future outcome.

 

 

 

The futures are not different just the motions are different. There is no future that is set up like a path. Just motion and thought. Your concept of the term future leads you to think that “the future” is a unit of time different than some other “future” unit of time.

 

I am making choices on which keys to hit as I type this, what am I doing, time traveling between many “mini” futures.

 

You won't be in the same place, though --because the surface of the planet is in constant motion. Also you would burn up resources walking around --you can't "walk backwards".

 

 

 

Forward, backward. When you say that you cant walk backwards, backward is just a movement or direction that is perceived to be contrary to the normal motion or direction that we are used to.

 

Backward is a motion in a specific direction, the same as forward motion, is there really a difference between these motions. No! you call one motion forward and the other backward, both are motions.

 

I put a mark on the ground and walk 5 feet from it in a direction. I turn around and walk back 5 feet to the mark. I am in the same place from where I started. Are you saying that if I did not turn around and walk back, but reversed my motion, I would not be able to?

[roosh]

Hey guys,

 

I haven't read the entire thread, but the nature and existence of time is a discussion I am relatively familiar with (relative to what I won't say ).

 

I would be of the inclination that time is an illusion; I'm not sure there is any evidence to support the existence that time is real or physical, that doesn't require us to assume the conclusion.

 

The most basic way of looking at it, I think, is to consider how we "measure time"; what we tend to use are regularly recurring processes; but if we examine these processes we can see that at no point is there a physical property of the universe, called "time", ever measured; instead, what is actually measured is the recurring process. In an atomic clock, the periodic oscillations of the Caesium-133 atom are measured, not a physical property called "time". Someone mentioned earlier in the thread that time has to exist, otherwise there would be no cylces, but that appears to be an unjustified assumption. The cycles occur, or exist if you want, and we use them as standard units of comparison. That is, we measure a process by comparing it to the number of oscillations of the Caesium-133 atom to give us the "time" the process takes. We then measure other processes using the same standard unit so that we can compare the different processes in meaningful terms. At no point in the process is something physical called "time" measured. From this perspective time is simply a system of measurement, not a physical property to be measured.

 

 

Another aspect of time is the idea of "past" and "future", but thse, I believe, arise from the human capacity for memory and projection; that is, we experience the present moment, which subsequently changes and we form a memory of it; we also imagine experiences which have not yet happened, which we label "the future"; this creates the impression of a linear progression through time. But, every observer can only ever experience the present moment; if we arrive at the conclusion that past and future co-exist with the present, then it requires and assumption on behalf of every observer; that is, it requires every observer to assume the conclusion that past and future co-exist with the present.

[alpha2cen]

What makes time moving forward?

Entropy?

Is this time moving driving force?

[latex]\Delta S_{Universe, future}- \Delta S_{Universe, present}>0[/latex]

[mireazma]

Wow, huge leap in time for this thread from 2007 to 2012 (pun intended)

 

Why are you arguing whether time exists or debate its nature without mentioning space? I personally can't differentiate between time and space, as it's the same thing but in 2 colors. I think space is generally easier to comprehend so one should start from describing space first. Time sounds more mystic than space but after all it's another kind of space. It's more difficult to grasp because we only experience (generally) 2 dimensions of time and only one direction. But one can contemplate very easy the other direction of dimension 1. The real difficulty starts from more than 2 time dimensions.

 

What happens if time would "flow" backwards?

Well, first, it doesn't even flow. It's just there. It's like you said the road flows as you exist on it. But it's you who position yourself here, then there then back here, so on. You are traveling with respect to the road and not the other way around. I'm saying this because you initiate the movement, not the road. It's just you can't go backwards (or can you?)

If we call a 6-th sense the one to perceive time with, say "seeing", we'd say we subjectively "see" time through a slit.

 

Second, to answer, we would merely experience unwinding events. I like (please, indulge my personal preference) to see all events laid on a R³ space. With different observers come different referential systems, so origin is not relevant. The x axis I like to call destiny, y axis -- simultaneity and z axis, alternity. The cause-effect feature of 2 events is in fact the vicinity of 2 points in time.

Let's say you are positioned at coordinate xyz. The observable course of events is just a horizontal plane xy at an alternity "height" y, containing that point (you). A line of this plane is a continuous cause-effect chain of an arbitrary infinitesimal events.

Note that we call some event "the cause" of an other -- "the effect", depending on the direction of this line. If we take the positive direction of x (the one we experience), we say you knock out a pen on the table and caused it to fall. If you see it backwards, you don't say your finger retracted and the pen followed your finger but instead, the pen rose from the table and pushed your hand, causing it to retract.

So a point (event) is the cause/effect of all of its vicinity points. You can draw a line, a curve and yes, even a circle on this plane to determine some causality. You tamper with events, being one of them, and observe the causality only in x positive direction, as discussed. As the causality line approaches x component 0, you make less sense (have a lower "resolution") of the causal feature until the line is perpendicular to x and has only a y component, when you can't relate a cause/effect between events on that line and sense all of them as instantaneity. So instantaneity is a line of causality parallel with simultaneity.

The relativistic concept of difference of simultaneity would lie in the rotation about alternity (z) of the reference system but maintaining the xy time plane.

 

Now to the 3rd dimension. If you could go back in time and alter the known course of actions, the only possible way you could alter is to "act" a changed "weave" of causality, different than the one with the known course. This new weave is a higher/lower xy plane, on the alternity axis. But you could only cause so little alteration, that is, to the size of an infinitesimal point in time, to move exactly 1 plane up/down, "after" which you continue on the current new xy plane. The more you do this alteration, the more you get further from the original plane.

 

This is the way I like to look at time.

[Dekan]

Perhaps our modern ideas about "time" have been strongly influenced by the invention of cinematography.

 

A reel of film can be run - and projected onto the cinema screen - in either a forwards or backwards direction. It can show us a seed expanding into a flower - or, with the film run backwards, the flower contracting into a seed. Both seem equally valid on the screen.

 

This is bound to give us the idea that "time" can go either way - forwards or backwards.

So I suspect that the concept of time travel, and its huge popularity in SF, arose from motion pictures.

 

Were there any pre-cinema SF stories of time-travel?

Edited December 10, 2012 by Dekan

[StringJunky]

Perhaps our modern ideas about "time" have been strongly influenced by the invention of cinematography.

 

A reel of film can be run - and projected onto the cinema screen - in either a forwards or backwards direction. It can show us a seed expanding into a flower - or, with the film run backwards, the flower contracting into a seed. Both seem equally valid on the screen.

 

This is bound to give us the idea that "time" can go either way - forwards or backwards.

So I suspect that the concept of time travel, and its huge popularity in SF, arose from motion pictures.

 

Were there any pre-cinema SF stories of time-travel?

 

Einstein was around at the dawn of moving pictures and iirc he asked these very same questions...the rest is history.

[michel123456]

Perhaps our modern ideas about "time" have been strongly influenced by the invention of cinematography.

 

A reel of film can be run - and projected onto the cinema screen - in either a forwards or backwards direction. It can show us a seed expanding into a flower - or, with the film run backwards, the flower contracting into a seed. Both seem equally valid on the screen.

 

This is bound to give us the idea that "time" can go either way - forwards or backwards.

So I suspect that the concept of time travel, and its huge popularity in SF, arose from motion pictures.

 

Were there any pre-cinema SF stories of time-travel?

Ill have to dig to find an old thread where I went to argue that the reverse movie is not a good representation of time reversal. The argument is that all 4 fundamental interactions must be reversed, not only motion. One should imagine reverse matter under reverse energy acting reversely.

Edited December 10, 2012 by michel123456

[imatfaal]

Perhaps our modern ideas about "time" have been strongly influenced by the invention of cinematography.

 

A reel of film can be run - and projected onto the cinema screen - in either a forwards or backwards direction. It can show us a seed expanding into a flower - or, with the film run backwards, the flower contracting into a seed. Both seem equally valid on the screen.

 

This is bound to give us the idea that "time" can go either way - forwards or backwards.

So I suspect that the concept of time travel, and its huge popularity in SF, arose from motion pictures.

 

Were there any pre-cinema SF stories of time-travel?

 

The Time Machine by HG Wells was in 1895 which is about the same time as Lumiere and other were first demonstrating the ability to show moving pictures via film. And way before that Scrooge is transported back and forth by the Ghosts in Dickins's A Christmas Carol. There was a rush of time travelling books in the era of the Time Machine - I am unsure if that was due to the cinema effect. Wikipedia lists "Memoirs of the Twentieth Century (1733), by Samuel Madden," as one of the earliest examples of someone going back in time (an angel) rather than merely falling asleep and waking up in 100 years etc.

 

The greek myths were incredibly inventive but I cannot recall anything from antiquity about going back in time.

 

Ill have to dig to find an old thread where I went to argue that the reverse movie is not a good representation of time reversal. The argument is that all 4 fundamental interactions must be reversed, not only motion. One should imagine reverse matter under reverse energy acting reversely.

 

 

But surely all the interactions (except some weak decay?) are time (charge and parity) reversible / invariant - ie if the movie were detailed enough we could not tell which way it was running. In the real world we can tell because there's entropy and loss of order through heat etc. I think, but I am not by any means sure, that gravity will remain attractive, like charges repel/oppostite attract etc

 

Hyperphysics CPT invariance

[dripto biswas]

my dear friends, an infinite number of concepts are based on time. but if we didn't measure it, it would not have existed.

[phyti]

Consider the light clock. We count the number of cycles for light moving a distance of 2d, d being the separation of the mirrors.

Isn't this just comparing vt motion of an object with ct motion of light?

The clock event t is used to correlate some event of interest for the purpose of ordering and recording for future reference.

 

As for the person choosing between futures, they form their future by their choice according to current conditions.