could someone explain the relationship b/w time and space?

Question

my physics professor was trying to explain this by saying confusing statements like "we're nowhere and we're going nowhere", and other things about 4 dimensions. Could someone simplify this mindbogglingly relationship?

Answer 1

Lovingdad is right.

Einstein usually spoke of the space-time continuum. He envisioned time as just one more axis in space-time (that is to say, you can go east-west, north-south, up-down, or through time). Einstein said that, when at rest, we were always travelling at the speed of light through time.

Think of it as a car doing runs on a salt lake (like those that you see to break spped records). The car can go at a speed of 300mph. Lets suppose Bob does 4 runs at different times, and each run his time from when he passes the start flag to when he reaches the end flag is longer. When Bob looks at the results, he realizes that his first run was a straight line, but his 2nd run was slightly akewed so that it wasn't a straight line but sloped to the left. The 3rd run was further sloped to the left and the 4th was even more so. Why were the times of the 2nd, 3rd and 4th runs longer?
Because in the 1st run, the car was using all its speed to travel on a straignt, lets say east-west, line. By the 2nd run, part of the cars speed was being used to travel on a north-south axis instead of on the east-west axis, so it took the car longer to travel the same distance in the east-west axis. So, as you see, since the car can only do 300mph max. the speed in one axis is relative to the speed in another axis (is afected by the speed in another axis).

Going back to my first postulate, that we travel through time at the speed of light. Space-time has 4 axis (east-west, north-south, up- down and time). At rest, we travel through time at the speed of light, but as soon as we start moving in any of the other axes, we start "bleeding" our time speed. This explains Einsteins paradox of an astronaut returning from a space mission to find his twin brother is older than him (he "bled" more speed from the time axis, while his brother was "stationary" and thus travelling at the speed of light through time). It also explains why nothing can travel faster than the speed of light.

Answer 2

Space and time are a single concept. It is called spacetime.

Time is defined as the period that it takes light to travel a distance. The distance is how far the photon has to travel. (Einsteins definition.) The problem is that time depends on your frame of reference. This is a big problem.

To solve this problem scientist have codefined them using spacetime as a single metric. With space time being defined by both the distance and the time. This makes reference frames invariant.

This is invaluable in solving complex physics problems.

Think of spacetime as defined by a curvature. When curvature is fixed the realationship between the time and distance is fixed. This is how we usually operate. But, during acceleration the spacetime curvature changes.Then the distance or the time changes depending on your perspective to the event.

Answer 3

That is a tricky one. But space and time are really just two different aspects of the same thing. And the relationship between them isn't real easy to 'visualize' from the mathematics. But the thing that 'seperates' two 'events' and allows us to think in terms of 'causality' is either space or time. And the distinction between whether or not the seperation is 'spacelike' or 'timelike' depends on the relative velocities of the two events. If their relative velocities are slow (compared to the speed of light) we say their seperation is spacelike. But if their relative velocities are large (an appreciable fraction of the speed of light) we say that their seperation is timelike, due to the temporal dilation effect that takes place at relativistic speeds.

It takes a fair bit of time studying relativistiv mechanics before you really start to get a 'feel' for what happens. And it is *not* intuitive in any sense.

HTH ☺


Doug

Answer 4

from an observers standpoint, time and distance (space) are inversely related. The further "forward" you look in space, the further "back" in time you are actually seeing. This phenomena comes from the limitation on the speed of light.

A good example of this is when we look at stars in the sky, we are actually seeing them in their state 1000's to billions off years in the past.

Answer 5

I could try to put this in common speech, but I'm afraid at this
hour I'd really mess it up.

So go here: http://en.wikipedia.org/wiki/Spaceti

Answer 6

It's simple. To have time, both space and matter are required.

Without space, there is no room for matter. Clocks are made of matter, and without clocks, there is no time.

Similarly, matter is required, because clocks are made of it, and without clocks, there is no time.