On Wellsian Time Machines

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ProgBoy1

Temporal Novice
A real operating time machine can't go through time! Rather, it needs to jump in and out of time. Also, the time machine would need to be a 'space machine' as well. How can this be? Well, just hold on to your hats, and the ProgBoy1 'll show ya. First of all, the Earth moves, does it not? And the Solar System, right? And the Galaxy, right? So if we take into account all these motions and add them up, 1969, say, is quite far away! So if your time machine was sent back to 1969 with moving in space as well, you'd be stranded! (With a wormhole, however, we do not have this problem.)

For the first objection, say you have a time machine that travels through time. Say we want to go back to 1969. (I don't know why I keep putting that date in, I wasn't even born then...) In accordance with logic, then, the time machine will explode one micro-moment before we press the button to send it on its way!!! How can this be? Well, a time machine that travels through time must occupy approximately every spatial and temporal instant between its destination in the past and right now. So the time machine must be in its exact same location it was a micro-moment ago, before you pressed a button. Now according to Euclid (or Euler, I forget which...) two points cannot occupy the same space. So your time machine would explode before you pressed the button. Now this leads you into yet another paradox: If you exploded and were killed before you even pressed the button, then how was the button pressed? Maybe the very explosion somehow pressed the still-intact button... I dunno...
happy.gif


Yes, yes, I know that my second objection (one must travel through space as well) still applies in the first, but the same paradox applies! So what if the time machine collides with only part of itself? It still will explode before you press the button!

Can some-one please help me with the above paradox? Unfortunately, this one is too tough for even the ProgBoy1 to solve!

P R O G B O Y 1 !

------------------
 
Space and time are interconnected (hence the phrase space-time) so maybe certain spatial properties have correlating temporal one's as well.

When you're in a moving train and you toss a coin, the coin (seems to) go straight up and back down. (Instead of appearing to fly back, opposite the direction of motion). This is because it's intertia kept the coin going at the same pace as you.

An observer off the train would note the coin really made an arc through space, but the coin tosser wouldn't notice this.

Maybe a temporal intertia acts on a traveling time machine too, seeming to keep it in one spatial point, even though the universe is constantly moving.

On the second comment, two points can occupy the same space, as long as they're seperate temporally. A point is a combination of spatial and temporal coordinates. So a time machine might exist here at 3:10, but it didn't exist there at 3:09. (remember, everthing is moving, so the place the time machine departed in is quite a distanceaway) It wouldn't be a problem when looked at from a higher perspective.

You notice in 'The Time Machine', the traveller returned to a different spot than when he left, saving Mr. Well's from offering an explaination. That sly dog.


<This message has been edited by Lara (edited 08 February 2001).>
 
Glad someone started a thread on this.

My romantic nature stills leaves me with loving the Wellsian "Time Machine" concept as my favorite of all scenarios.

Stephen Baxter's "The Time Ships" (Copyright 1995, Pub. Harper-Collins 10 East 53rd St. NY NY 10022) is probably the best work ever done in this genre.

Baxter manages to get around all the common paradoxes that are rampant in this type of speculation and does it with flair and style.

In the end of course, you realize (as you always did from the outset) that this methodology is of course impossible. It is based on what man knew ( or better, DIDN'T know) in Wellsian times, but Baxter seems to make you not care about why it can't be so. You just go with it because it's pure fun.
 
Space and Time are only half the story, at best. What about Matter and Energy? Matter and Energy are real; space is the place where matter resides and time is only a measure of the duration of movement of matter.
 
Very good "NoTime" you are closer to understanding the nature of time then you realize.

Here is a question that might help. What is it about time that make time travel impossible?

You said that time is only a measure of the duration of movement of matter. On the surface this would appear to be a good reason why time travel is not possible, however their is a more basic definition that disallows time travel.
 
TimeMaster 1a:

I don't mean to interrupt here, (please forgive), but you raise a very interesting question.

If I may comment....

I personally would not use the term "impossible" to say what reality Time Travel concepts may or may not hold.

I will however say that I think that "Time Travel" as many (indeed most) people think of it is "impossible". (The qualifying argument being "as people think of it" in this case.

My thoughts go toward the issue of our basic, fundamental MIS-understanding of just exactly what "Time" is.

In the classic sense, to me there is NO future one can TRAVEL "to". It does not exist for the simple reason that it has not happened. Fundamental. That easy.

And basically the same for the past except that is has gone by "forever". It also does not exist. In this case, "any longer".

To me, we have come to view time as something tangible, but in reality, it is only a MEASUREMENT. An invention of the mind of man to explain the lapse between cause and effect.

Experiments that exemplify this (such as the classic double-slit polarized EPR Paradox,) only reflect our misunderstanding of time. Since this experiment remains unsolved even unto this day, (but originated in the last century), it points out what we have yet to learn about even the fundamentals of the world around us.

Actually, given our present understanding of time, it's difficult for me to imagine how anyone could ever view time as being anything other than "right now". From THAT observer's point of view of course.

One analogy would be the "flat earth" theory of long ago.

Most of society was at one time convinced that sailing too far into the ocean would result in your "falling off the edge of the world". And based on the limits of visual observation at the time, it SEEMED logical. The problem was of course that there never was an "edge of the world" in the first place. No matter how much we thought it to be so.

Consequently, all theories based on the acceptance of the "fact" that the edge of the world was there, are fundamentally flawed from the outset. The basis is simply not true in the first place!

So....

I have this feeling that we here now are also short sighted in our concept of just what "time" is. And this fundamental flaw in our concept leads us down roads of speculation that simply cannot be true in the first place.

Just because it's now the 21st century, does not by any means constitute that we have reached full knowledge of the workings of the universe.

As I see it, if we are to grasp the solution to "Time Travel", we must first come to grips with just what "TIME" is.

I don't think we've done that yet.
 
"--As I see it, if we are to grasp the solution to "Time Travel", we must first come to grips with just what "TIME" is.
"

i know people who know how to drive cars,but havent the faintest on engine mechanics...


FastWalker2
 
DaViper I do not often ues the term "impossible", however after discovering the true nature of time I find that not only is time travel impossible now it well never be possible.

"To me, we have come to view time as something tangible, but in reality, it is only a MEASUREMENT. An invention of the mind of man to explain the lapse between cause and effect."

With this statement you are very close to the true nature of time. Here are some key questions A: How do we determine reality? B: What does it mean to measure time?

"I have this feeling that we here now are also short sighted in our concept of just what "time" is. And this fundamental flaw in our concept leads us down roads of speculation that simply cannot be true in the first place."
I have read truer statements, I just can't remember when.

A fundamental flaw I see all the time is the ideal that time dilation is a function of speed.
 
The speed of light as we know it is part of our time frame like everything else we experience. Other time frames have their own speed of light, if there are other time frames. I don't think that the speed of anything is involed in time travel, if time travel is even possible. On the other hand, if we think something is possibe, then it probably is.
 
fast:

"i know people who know how to drive cars,but havent the faintest on engine mechanics..."

Me too. But the people that BUILT the cars most certainly do.

TimeMaster 1a:

"DaViper I do not often ues the term "impossible", however after discovering the true nature of time I find that not only is time travel impossible now it well never be possible."

I'd say I agree with you 100% as far as "Time Travel" is thought of by most folks. It goes to that which I believe is a fundamental flaw in our understanding of time in the first place.

As to...

"A fundamental flaw I see all the time is the ideal that time dilation is a function of speed."

Yes, this is one I'm guilty of myself in my DEPICTIONS of it, although I do know that there are several forms of Time Dilation. The cause most commonly referred to as "speed" is actually the DIFFERENCE in relative velocities from two differing viewpoints. One could generally say that people on the earth experience no time dilation between (among) themselves but this is not technically accurate either. The very act of YOU walking away from ME induces SOME time dilation but so minute that it is probably immeasurable by any methods currently available to us. Especially in view of the fact that the dilation that occurs on the Space Shuttle is also so minute it takes two PERFECTLY synchronized ATOMIC (Cesium) clocks to measure it. And we're talking a relative difference of at least 17,500 mph. Not 4 or 5 feet per second.

But you are correct. Speed does not make my clock slow down. A difference in velocity between you and me makes MINE slow down relative to YOURS. I'm not sure anyone knows WHY this is so, just that it is. And as predicted.

Another cause we are exploring at the moment is gravity itself. And Frame Dragging if the gravity well is spinning.
 
DaViper:

These are all good sites and I hope everyone takes the time to read them.
Frame dragging is another fundamentaly flawed concept. The gravity probe will validate this statement by failing in its mission to measure how space and time are warped.

SPEED and VELOCITY are commonly given the same meaning. In physics, speed and velocity have definite, separate meaning. The speed of an object indicates how fast it is moving, that is, the distance the object will travel in a given time. It tells nothing, however, about the direction in which the object is moving. The quantity in physics which combines the speed of a body with the direction in which it moves is called velocity. So we see the only deference in speed and velocity is the direction of movement. If you accept that Time Dilation is not a function of speed then it is also not a function of velocity.

Time Dilation exist as a function of VELOCITY only in an indirect way. We can see this by looking at the meaning of SPEED. As stated above speed is the distance that an object will travel in a given time. This means that Time Dilation exist as a function of DISTANCE. Speed and velocity tells you how fast and in what direction the distance changes, but they do not cause time dilation.
 
TimeMaster 1a:

"The quantity in physics which combines the speed of a body with the direction in which it moves is called velocity."

Actually, no. What you're referring to here is called a "vector" in Physics.

One can find the definition of "Speed", "Vector" and "Velocity" at the following site which is the Harcourt Dictionary of Scientific Terms.
http://www.harcourt.com/

In Physics terms, Speed is defined as...

SPEED -
Physics: in general,the time-rate at which any physical process takes place.

Mechanics: the time-rate of change of position without regard to the direction of motion; i.e., the ratio of the distance traveled to the time elapsed.

Optics: see FOCAL POWER.

Graphic Arts: a measurement of the light sensitivity of a photographic emulsion.

(with a couple other definitions for other sciences thrown in...

and...

VECTOR -
Mathematics: 1. a mathematical quantity that has both magnitude and direction.a mathematical quantity that has both magnitude and direction. 2. a one-dimensional array.a one-dimensional array.

Physics: a physical quantity that has both a magnitude and a direction and that adds like displacement; velocity, acceleration, and force are prime examples.

(This would be the one you refer to above as "velocity".)

Computer Programming: a data structure representing a one-dimensional array that uses an index or subscript to locate an item.

Robotics: a set of values for the operation of a robot in which magnitude is represented by the length of a line and direction by the orientation of the line.

Aviation: 1. a heading issued to an aircraft to provide navigational guidance by radar.a heading issued to an aircraft to provide navigational guidance by radar. 2. to guide a pilot, aircraft, or missile by direct communication.

(Notice no "speed or velocity" involved.)

Military Science: in air intercept, close air support, and air interdiction usage, a code meaning, "Alter heading to magnetic heading indicated."

Medicine: the carrier of an infectious agent, which acts to transfer an infection from one host to another.

Molecular Biology: any DNA molecule that can incorporate foreign DNA and transfer it from one organism to another.

Also, VEHICLE. (Going back to a Latin word meaning "to carry.")

...which obviously means several different things depending on the application one uses it for..


For intance, in Physics it involves both velocity AND direction. In Aircraft terms it only involves direction.

and velocity has even more depending on the application such as one where it can and DOES mean the same thing as speed is in ...(from the same dictionary)...


VELOCITY -
Mechanics: the time rate at which a body changes its position vector; velocity is a vector quantity whose magnitude is expressed in units of distance over time, such as miles per hour. (From the Latin word for "speed.")

Notice how in your example "velocity" is actually a quantity OF a vector, whereas the Vector itself is the definition of direction+speed, not velocity itself.

or...

velocity dispersion Physics: the separation of radiation into its components of velocity, such as in the sorting of electron velocities as electrons are passed through a magnetic field.


See the site for more definitions of velocity..they are too numerous to list here.

Way more than for Vector even.
 
TimeMaster:

P.S.

By the way, Time Dilation has NOTHING to do with distance at all. The Time Dilation itself is a DIRECT Result of the difference in RELATIVE velocity of any two given bodies.

And frankly, even Vector doesn't enter into it. Gravity however does, but in a most peculiar counteracting way when one of the bodies is on or near a large gravity well, and not the other.

The Space Traveler who travels to the far reaches of the Universe at 99.999% of Lightspeed experiences the EXACT same Time Dilation rate as the Traveler who goes 99.999% of Lightspeed while merely orbiting the Sun within our own Solar System for a journey of the same relative duration.

(Without taking into consideration the gravitational influences each would encounter differently which WOULD skew the co-incidence, but distance has nothing to do with it.)

As to your predictions on Frame Dragging, well, all I can say is that we shall see shant we. We shall see.
 
DaViper:

You said:
"Notice how in your example "velocity" is actually a quantity OF a vector, whereas the Vector itself is the definition of direction+speed, not velocity itself."

I see no conflict with the above statement and the two statements that follow, since displacement is a vector quantity, and velocity is the rate of displacement.
Quantities which require both a magnitude and a direction for their complete description are called VECTOR QUANTITIES. Therefore VELOCITY is a vector quantity.

"The speed of an object indicates how fast it is moving, that is, the DISTANCE the object will travel in a given time. It tells nothing, however, about the direction in which the object is moving."

"The quantity in physics which combines the speed of a body with the direction in which it moves is called velocity."

These two above statements are direct quotes from my Physics text book, therefore I feel compelled to accept them as accurate.

You said:
"By the way, Time Dilation has NOTHING to do with distance at all. The Time Dilation itself is a DIRECT Result of the difference in RELATIVE velocity of any two given bodies."

To say that Time Dilation does not exist as a function of DISTANCE is like saying that the root of a tree has nothing to do with the growth of the leaves.

It is not logical to say "The Time Dilation itself is a DIRECT Result of the difference in RELATIVE velocity of any two given bodies." and at the same time deny that it is the RELATIVE distance between any two bodies that is at the root of Time Dilation.
 
TimeMaster 1a:

Thanx for the response. Let's proceed. Point by point if you will.

You said:

<You said:[BR>"Notice how in your example "velocity" is actually a quantity OF a vector, whereas the Vector itself is the definition of direction+speed, not velocity itself."]

That is correct. I did.

And you say...
<"I see no conflict with the above statement and the two statements that follow, since displacement is a vector quantity, and velocity is the rate of displacement.">

I do, but......OK.
And then...

<"Quantities which require both a magnitude and a direction for their complete description are called VECTOR QUANTITIES. Therefore VELOCITY is a vector quantity.">

I agree, but then now I'm confused as to what it is YOU are saying since the above statement is in accordance with the quote I provided (from Harcourt), yet seems to be at odds with your ORIGINAL STATEMENT that as follows: (and please correct me if I am wrong)

-----
' ""The quantity in physics which combines the speed of a body with the direction in which it moves is called velocity." '
-----

Sorry, but you have baffled me here with a seeming contradiction. In YOUR quotes.

(I thought I was the one proporting that velocity is a vector quantity, not the state of a vector as YOU purport. Based on the evidence I provided of course.)

And then:
<"The speed of an object indicates how fast it is moving, that is, the DISTANCE the object will travel in a given time. It tells nothing, however, about the direction in which the object is moving." [P>"The quantity in physics which combines the speed of a body with the direction in which it moves is called velocity."

These two above statements are direct quotes from my Physics text book, therefore I feel compelled to accept them as accurate.]

Ok. I'll accept that YOU do. And then ask how we can the resolve the difference between your Physics textbook and the Harcourt Dictionary, as far as the SECOND statement above is concerned.

After all, we can't even agree to disagree if we use reputable sources that conflict with each other now can we. :-)


You said:
"By the way, Time Dilation has NOTHING to do with distance at all. The Time Dilation itself is a DIRECT Result of the difference in RELATIVE velocity of any two given bodies."

Yup, I said that. But I will go a step further.

In the above case, I'm referring to Time Dilation in the original sense as it was discovered and predicted by Einstein's first disertation on it. Namely the form of it that DOES indeed pertain ONLY to Velocity.

(There are SEVERAL forms of the manifestation of Time Dilation. I was in this case referring to only ONE of them. I can even stand corrected if you like, but if you will, please forgive the single mindedness of this particular focus as to which manifestation.)

I concede that there is another and even contradicting form of Time Dilation that relates to gravity which indeed WOULD be affected by Distance, but perhaps shortsightedely, I was merely referring to but one of them here, since the two are not directly related. They are actually opposing forces, not coincidental ones.

The thing here is, that the gravity induced form of Time Dilation is so much weaker, so much less in significance IN COMPARISON TO the velocity induced form, that it's effect on the velocity induced form is almost entirely negligible.

Remember the scenario I used where two people walking away from each other do induce Time Dilation, but in comparison to the Space Shuttle vs. The Earth, the human scenario is negligble.

So please allow me to modify the statement just a tad by saying, that Distance has ALMOST nothing to do with it. Certainly compared to velocity anyway.

Then YOU said:

"To say that Time Dilation does not exist as a function of DISTANCE is like saying that the root of a tree has nothing to do with the growth of the leaves."

Well, OK given the above concession. But in comparison, I still stand by the original statement in a very general sense.

And then you said:
"It is not logical to say "The Time Dilation itself is a DIRECT Result of the difference in RELATIVE velocity of any two given bodies." '

Of course it is.
Because it is true!
As predicted.
And measured and verified by repeatable experiment.

(and further...)

"and at the same time deny that it is the RELATIVE distance between any two bodies that is at the root of Time Dilation."

You're mixing Apples and Oranges here.

Dilation as a result of relative velocity has NOTHING to do with distance. And I stand behind that statement.

But to clarify, I'll agree that Dilation due to gravity does. But it's like licking raindrops in a rainstorm trying to catch all the water falling from the sky.

I would speculate however that an individual at the event horizon of a Black Hole observing a traveler moving away from him at the speed of light would constitute two guys that could communicate in real time with each other (given the technology to do so), since in THAT one particular scenario, the dilation would be cancelled between them.

Peace.

This is good.
 
DaViper:

From EINSTEIN book RELATIVITY :
Chapter XII
THE BEHAVIOUR OF MEASURING-RODS AND CLOCKS IN MOTION

"Let us now consider a seconds-clock which is permanently situated at the origin (x'=0) of K'. t'=0 and t'=1 are two successive ticks of this clock. The first and fourth equations of the Lorentz transformation give for these two ticks: t=0 and t= 1/sqr root of (1-(v^2/c^2)).
As judged from K, the clock is moving with the velocity v; as judged from this reference-body, the time which elapses between two strokes of the clock is not one second, but 1/sqr root of (1-(v^2/c^2)) seconds, i.e. a somewhat larger time. As a consequence of its motion the clock goes more slowly then when at rest. Here also the velocity c plays the part of an unattainable limiting velocity."

What definition of velocity do you think Einstein was useing when he wrote this?
 
TimeMaster 1a:

The one he uses to describe the equation itself.

"...a consequence of its motion"

Since there is no reference to "direction" anywhere in the equation, how can it be anything other than just the relative differences in velocity as "speed"?

Or, for the sake of his own explaination, the classic Mechanical one.
 
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