Well, I finally got to watch some Dr Who.... and "Hooked" isn't quite a strong enough word for it. Even in all caps!
I mean, I used to be a Star Trek fan, a Star Wars fan, a Red Dwarf fan... and I have to say I think I like the Dr Who universe the best. (though Red Dwarf is still a high second, but the other two are starting to pale in comparison)
Anyway, one of the things I like most about the storyline is that they have a lot of fun, and have set it up so they would seriously have to try to write themselves into a corner, yet the "rules" make a lot of sense, namely the rules of time travel.
I have had my own theories of "Time Travel" and I have a bit of a different perspective on things than the conventional "Hollywood" definition. The Dr Who storyline is the closest fictional series to aligning to these thoughts.
My basic thoughts are:
We are all traveling through time, but some of us get there faster.
The events in a person's past cannot be changed (at least as far as the individual's experience is concerned).
As I have read various things over the years, it seems that I have come to some of the same concusions as are generally accepted, such as causality, but in a very roundabout way:
If "time travel" were possible in the conventional sense (conventional "hollywood" definition being that it is a dimention, not a scaler, that can be traversed as easily as distances in space, if only you had the means to do so), then someone at some time "in the future" would have "invented" a "time machine" and no matter how well it was policed, someone at some time would eventually take the technology back through time to an earlier point (for profit or ideals), and eventually all points in time would become homogenous... meaning that eventually, we would be living next door to dinosaurs (possibly talking), and zoos would potientially carry every spiecies of every kind of life form that will ever be known... and we would know no other way of life.
Obviously, on this Earth, this didn't happen. Ergo, there is no such thing as a "time machine" that would allow a person to go back in time... it being noted that, strictly speaking, "travel BACK in time" is what is forbidden by the laws of the universe in the sense that one could go back and change anything. This does not exclude "travel to the future" or "Observation of the Past", but it potentially bans "Observation of the Future" (though logically, it only excudes observing the future up to a point when such a technology is available, but we would not necessarily have any knowledge if that technology ever becomes available until it does).
This is a logical thought problem and partial solution, not a pysical science solution, by the way.
However, it should be noted that we are ALL, in a sense, time traveling. You are farther ahead in time now than you were a miniute ago, or a day ago, or a year ago, or even a few words ago. We are all moving ahead in time, at "roughly" the same rate.
But strictly speaking, we are not all "time traveling to the future" at the same rate, at least if the theories of relativity hold any water.
Supposedly, a "future traveling time machine" could be constructed from materials and technology we have around right now, in that, if you accellerate something to a significant fraction of the speed of light, "time slows down" as far as what we would see looking at the object (imagine shooting a clock at half light speed (any direction) and watching the hands of the clock. They would appear to move slower, even though someone moving along with the clock would not think that a second wasn't a second).
So, we could actually send a person out into space at an extremely high rate of speed (and at a economic cost that nothing could afford, it should be mentioned), so that it would take them 50 years to get back to earth, but "on board" only 10 years would have passed, in essance sending the passenger ahead by 40 years.
If the whole cryogenics thing worked (and it doesn't), it would have the same effect: a person would be removed or slewed in time so that the rate time passes for everyone else would be relatively faster than for the individual, and in essance the person time traveled into the future.
More in a moment...
But what use would future time travel in this sense be? There is no return trip!!!
Regardless of the method of reaching the future faster than everyone else, there are one or two problems with the appeal of such a thing, chiefly:
Why would you want to?
-Everyone you knew is either just that much older than you are, or dead.
-Your skill set is that much out of date.
-You might be declared dead and your assets disposed of (so, unless you brough gold bullion with you, you are penniless, and you can't garantee that it will be legal to sell precious metals in the future)
In essance, other than perhaps some value to historians, you have no value to anything, and no real garantee that you will have anything to make your life livable when you get to the future. You can't learn a bunch and go back and use that information... so why would you want to waste your life (and most likely die) trying to travel like this?
So, that's out. Can't go forward (reasonably, or usefully), and you can't go back (logically).
So, what's the point of this thread then?
To come in phase two: meaningful time travel
(please feel free to express your own throughts and ideas, discussions, etc, it's all for fun!)
Meaningful time travel....
We have already seen that, if we can believe that some manifestation of the effects of Relativity are real and observable, different things (atoms, clumps of atoms, bodies, planets, stars, galaxies, etc) traveling at different rates have a different rate of time passing on such things.
The simplest is an atom. An atom is an easy thing to work with, as its stable for the most part, and it's pretty much as small as you can get and still be mostly stable.
An atom vibrates (in many different ways) at specific frequencies. To a relatively motionless observer, these vibrations would slow down as the atom was accellerated closer to the speed of light. (this is what give us red shift and blue shift to tell how fast a star is moving towards us or away from us: the characteristic frequencies of light emitted by the elements burning in the star will be shifted higher or lower in frequency as the star moves away or toward us).
These effects are almost immeasurable on a daily basis, but they are there (I'm paraphrasing for time and effort, as I'm a bit lazy and boring about this stuff). Essentially, if a person (a body of atoms) is walking toward you or away from you, time is passing at a different rate than it is for you, though we don't really have a wrist watch that would be accurate and precise enough to ever measure this. The effect would be more pronouced if you thought about a pair of individuals moving away from each other at noon or midnight at specific times of the year, when the movement of the surface of the earth is aligned with galactic rotation, glactic movement, solar movement, earth's rotation and movement, etc... (though really, even these effects are so small we couldn't measure them all that well), and then run (drive, with a rocket propelled car) away from each other... you'd probably almost get a slight phase difference between two syncronized atomic clocks.
But the point is, there is a difference.
Generally speaking, though every atom of your body can be considered to have a different rate of time passing on them, it could be considered that the net sum of all these time differences totals to the same of that at your center of gravity, and that, for all intents and purposes of this argument, as long as you are a person, these atoms can be treated as one body throughout your lifetime (minus, of course, replacement of bodily materials and amputation).
So, you could describe what you do as a series of events passing along a metered line, as time will always pass for you at the same rate (even though that rate may and will be different than that of some other object or person).
This, for lack of a better way of putting it, is your time line. The Earth has a time line, your twin brother or sister (if they existed), would have their own time line... if something happens to you that is different than someone else, you have your own time line. It's pretty much linear, and unique to you. It only goes one direction (Scaler quantity, if you want to get technical): What has happened to you has happened, and nothing can change that. What hasn't happened yet can be changed, as it hasn't happened. The present is the effector of change.
Generally, in physics, or even in logic, if something is doing something, it'll keep doing that no matter what, until something causes it to do something else. This is true for inanimate objects as well as animate objects. For example:
A deer is thirsty. Because it is thirsty, it stops whatever it was doing and head for water.
Between the river and the deer is a hill. Walking up a hill isn't really all that much work for a deer, but it's still not going to go over the tallest part if it doesn't have to. Because it intersected the hill, it changes the path it takes to get to water. This is a deviation.
If nothing else happens, the deer will get to the river and drink, then ponder, in all its great intellect, what it will do with the next few moments of its life, such as eating something or finding a mate.
However, if a preditor is in its path, and it sees it or smells it, the deer will most likely do something other than make a bee-line for water. It might run, or take a different trail, or go back the way it came, or who knows what, but it will probably be something different than what it would have done.
What this example illustrated is that a time line for something (a person, a hammer, a planet) intersects with another time line (another person, a nail, some other astronomical object), the series of events making up the time line will be different than what they would have been.
When two timeline directly interact with each other, such as two people meeting each other, I call it a direct interaction.
When two timelines indirectly interact with each other, such as one person getting a job that someone else applied for, it is a fringe interaction.
When two timelines have NO interaction with each other, such as a worm burrowing unnoticed in Austrailia not interacting with a pile of bird droppings landing on a statue somewhere in Europe, well, there's no interaction. The time lines of the items being considered by be parallel, or have time passing at the same rate, or what have you, but there are no ties between them.
(in all actuality, everything affects everything else to some small degree, but if you look at timelines as being an infitesimally thin, but solid line, surrounded by fluffy tendrils representing the field of influence that object's timeline as influence over, the tendrils of fringe interaction would get smaller and fewer the farther away from the main timeline they got, distance from the timeline representing how strongly an interaction might be.)
For example, if I jump into a car, and go pick someone up, for all intents and purposes the car, myself, and the person I picked up are directly influencing each other. Our timelines are bound together, and our rates of time are the same. If we stop the car and go to different places, though, the timelines seperate. As we get farther and farther away from each other, we stop hearing or seeing each other, and as these informational ties are lost the amount of effect we have on each other's timelines decreases.
SO WHAT THE HECK DOES ALL THIS BORING NONSENSE MEAN?
Back with the example of the guy in a space ship going really dang fast, his timeline (from his perspective) had ten marks showing years passing by, between the times that his ship left Earth and returned, but Earth's timeline has 50 year marks on it (as well as pretty much everything else on the planet). This shows the time dialation effect of relativistic velocity (if this is real, of course, I haven't acually done any experiments on such things).
Soooo.... (assuming we have a magical device that allows a person to be relatively moving at a different velocity than someone else without seperating the people by an insermountable amount):
If we have person A, in his ship, traveling at a rate of half a second per second of "normal time" (such as what we'd see on Earth)
Person B is traveling at a rate of a third of a second per second
Person C is traveling at a rate of one second per second....
We let person A meet person C in five minutes, according to person C's time frame (so, 2.5 minutes have passed for person A), and person A gives person C a coin (or a clock)
We let person B meet person C in six minutes, according to person C's time frame (so, 3 minutes have passed for person B), and person C gives person B the coin (or clock) they got from person A
We decellerate everyone to the same time at minute 7.
(this will change when I can do the math... I ran out of time for now. Point is, you could relatively have something appear to be passing backward in time as it has been handed back and forth between time frames. According to the guy on the ship, he's traveled to the future. According to the planet, they have traveled to the guy's past, but in all actuality, they have both traveled forward at different rates There's a point I worked out years ago that I need to work through again in which I can't go to my past but someone else can...)
We let person A meet person B