Why does time go slower the faster you go?

Time does not necessarily go slower for you - to see this you really have to grasp the basic ideas behind special relativity.

The fundamental idea is that if two people are moving relative to each other at a constant speed and direction, then the laws of physics should be the same for both of them. They can each do an experiment - measure the speed of light from a distant star for example, - and they should agree on the result. So if you move by me at some big fraction of the speed of light and we both measure light from a star, we both will say it travels at a speed 2.999x10^8 m/s - even if you are moving toward the star. What we won't agree upon is the wavelength - that will depend on how we each move relative to the star and that is how the conservation of energy sneeak into th epicture (another law of physics).

Ok - so now you go shooting by me (let's say you're in a spacship) and you look at my clock. Because you are moving very fast the light from my clock has to travel some distance to reach you and takes some time. So, you look at my clock just as you pass me and then you look 1 second later (by your clock). What you see is the light that left my clock much earlier than 1 second ago - remember it has to catch up to you. So you conclude that my clocks are slow. I look at your clock and the same thing happens. After one second by my time, I look at your clock again, and see it showing a time earlier than 1 second and I conclude your clock is slow. But time passes normally for both of us.

Now, suppose after a year of travelling (in your time) you decide you want to turn around and come back to earth. So you have to slow down, stop, turn around and speed up to your original speed - you undergo acceleration. SO for this piece of the trip, even if you could do that instantaneously, you are not moving at a constant speed and direction. You experience a force, hence you know you are moving. This creates the outside difference thatresults in you coming back to earth two years older than when you left, but my aging many years. This is the famous twin paradox.

Now we can see the effects of time dilation (slow down) in some subatomic particles. There a muons with very short half life that are created when high energy comsic rays interact with molecules at teh top of the atmopshere. If you just did teh simple calculation of finding out how long it would take the muon to reach the ground, you'd find that it should decay prior to ever reaching the ground. The time is much longer than the half life. But we measure tehse muons on the ground because when you account for time dilation, there is plenty of time for them to reach us in their frame of reference. So their internal clock appears to run slower.

I saw a program on Sky by Steven Hawking - put basically he said that to travel at the speed of light (other than that actual substance) is impossible - because nature (or some other unexplained phenomena) prevents us from doing so. It does this by slowing the object attempting it down; this only applies to the object in question however, and everything not attempting that speed carries on as normal; this is how it's possible to travel forwards in time, and not backwards; nature slows down time for an object reaching to close to light-speed.

Backwards in time is completely impossible simply because of the idea of a paradox (a paradox, if you didn't know already is something that couldn't happen because of other events preventing it - the most basic example is if you travelled back in time and killed yourself. That couldn't happen; otherwise you'd die too right, because your from the future? And then, after your past self died, who would appear in the future to travel back in time to kill you?

However if you believe in the theory that there are loads of different dimensions stacked against each other, each similar - yet different (say one dimension you flip a coin and it landed heads; in another it might have landed tails) - perhaps time travelling would take you back to a dimension that is different; yet replicates exactly your own dimension's past.

Think I'm confusing myself here...best stop ><

Hope the first paragraph helped though :)

This is known as the twins paradox and is linked with general relativity, simply its because as you accelerate towards the speed of light the laws of physics attmpts to slow the object down by slowing down time in it, if time weren't slowed down on a train doing 99.999% the speed of light and a person runs up the carriage in the direction of travel, the person may inadvertaintly break the speed of light, so nature does it to stop that happening.

Short answer! If you were to reach the speed of light then time would cease to exist. The matter in question that was travelling at the speed of light would occupy all points in the universe at the same time Weird I know so that means photons of light in that reference frame do not actually move they are staionary yet I detect they move in my reference frame Anyone else shed light (PUN) on this.

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The faster you move through space, the slower you move through time; rule only applies for an object at constant speed moving in one direction. This was Einstein's initial theory of relativity, before he expanded it into the general theory of relativity. This is my layperson's understanding anyway.

Because the speed of light is independent of the velocity of the observer. If it were possible to travel at the speed of light, light itself would still travel away from the observer at the speed of light. This is only possible if a moving object creates its own time frame. However, most objects move at just a tiny fraction of the speed of light, so the time shift is not detectable.

This is the theory of relativity.

What are the implications of this word in Newtonian physics

re: "relative speed" or "relative velocity"?

It's all about perception given a specific reference point.

Newtonian physics only uses 3 dimensions: Length, Width and Depth.

Einsteinian physics uses 4 dimensions: Length, Width, Depth and TIME.

There is no such stuff as time, no past, present, or future. This is just mans bloody habit of pigeonholing things. He does it with everything else on the planet, so do you honestly believe that he would draw a line when he got to space speed and time. Time as we know it only applies to those of us who are alive and kicking, because when we die, we cease to be something to be pigeonholed, (other than being dead) but you or I being dead, are just a memory of someone still alive; so, anything to do with how man sees the universe and anything contained therein is all down to mans ability to categorise stuff.

I'm ashamed to answer this question