Why is then Time Travel possible?

[C3l7]

I do not think something could have a velocity less then zero. Because zero is stationary and less then zero would be negitive but depending on your point of view it would be positive. it is just a vector quantity.

 

[VantagePoint72]

omin,
I don't see where I implied I thought time was a force. What I meant by time slowing down causes the ticking to slow down was that since the clock's ticking is a measure of the rate that time passes, when time slows down the ticking must therefore slow down too. This doesn't require some phantom force, it just means that if one tick uses one unit of energy, then energy _from the perspective of the observer back on earth_ the clock is using energy at a slower rate. From the observer on the rocket, the laws of physics hold true. If I drove past you in a car traveling at a constant speed and threw an apple up, from my perspective I applied enough force to throw it straight up and then gravity brought back down. Newton's laws hold true. If you through an apple straight up, you would conclude the same for your own apple. However, if you were to argue that I must have applied more force since you saw my apple travel further (you would observe my apple travel vertically and horizontally), then you would be ignoring the movement of the car relative to you thereby giving the apple the inertia that causes the additional distance from your perspective. This is the core of your argument regarding the clock. The laws of physics hold true according to both observer in there own reference frame. You can't say that the laws of physics aren't being obeyed in another reference frame, one that's moving relative to you, it's a comparison of apples and oranges.

Time is simply a quantity of motion over distance. I see time as more of a cognitive symbol, a mathematical theory that represents the physics, rather than something that causes things, slows down or speeds up things. I see cause deriving soley from the physical objects, and time is a symbolic property representing those changes depending upon the characteristics of the physical substances and their speeds.

And now your making another impossible comparison: you're trying to solve a relativistic problem with classical thinking. Time IS something. Or more specifically, spacetime. Your velocity through one (space or time) affects your velocity through the other. When your velocity through time slows relative to another observer, they will view events as passing more slowly for you. You see, your thinking is backwards...time isn't a measure of cause and effect, cause and effect are product of your journey through time. The clocks expend energy at the same rate in their own respective reference frame. When time passes more slowly for one observer cause and effect or, to be more concise, events pass more slowly for them _from the other observer's perspective_. And as for your arguments regarding distance travelled, length contraction is the complement of time dilation and makes sure both observers see the other moving at the same velocity. There is no force changing the expendature of energy, the rate stays the same. Again, in each observer's reference frame, the clock uses energy at the same rate. However, the trips take different lengths (and to complement this, is a different distance) from each observer's perspective so one clock uses more energy since it had more time to do so. As for your last statement, time is not distance, as I said before it's the complement of distance, or more generally, space. How do I define time? A specific component of a single entity, spacetime, that is the dimension defining when events take place. As individual observers, time is relative to each of us, meaning that what view as simultaneous may not be simulataneous to me do to the fact that I can break up spacetime differently than you. The passing of events is an illusion as time doesn't flow, events are forever frozen in spacetime and cannot be changed. It is only our own motion through spacetime that causes reality to appear as it does. Time is not simply a relationist's way of separated events, it is the entity that, like space, gives meaning to the events. To sum it up:
"Space is what we measure with a measuring rod and time is what we measure with a clock." - Albert Einstein