1. Jun 30, 2008

### mtworkowski@o

Einstein's special theory of relativity states that if a massive object could reach light speed, then it would be frozen in time compared to an observer who was moving at anything less than the speed of light.

Time is a dimension in special and general relativity, right?

Wouldn't traveling at the speed of light make your reality lose the dimension of time?

2. Jun 30, 2008

### cristo

Staff Emeritus
No, it doesn't. Special relativity states that a massive object can never move at the speed of light.

3. Jun 30, 2008

### chroot

Staff Emeritus
The special theory of relativity does not say this.

The theory precludes the possibility for any massive object to actually go c, so it does not attempt to explain what would happen if one could.

- Warren

4. Jun 30, 2008

### Harut82

I agree

5. Jun 30, 2008

### mtworkowski@o

See, now we opened the thread back up, and it was a good one.

6. Jul 1, 2008

### pmb_phy

The term "dimension" as it is used in that statement refers to how many numbers are required in order to uniquely specify something like a point in a manifold (fancy word for "set" or "space"). It takes one number to uniquely a point on a curve. It takes two numbers to uniquely specify a point on the surface of a sphere. It takes three numbers to uniquely a point in space. Likewise it takes four numbers to uniquely specify an event. One has to give three numbers to specify where the event occured and one number to specify when the event occured. The set of all events is referred to as spacetime and is thus a four dimensional set/manifold/space. In this sense "time" is said to be a "dimension" in this space.
Since nothing can travel at the speed of light the question has no answer. The reason people say that time stops at the speed of light is because they use an extrapolation. Its used so that one can speak of null worldlines. The interval between two closely spaced events on a null worldline is zero.

Pete

7. Jul 1, 2008

### MeJennifer

The amount of time an observer measures between two events is determined by four dimensions. But I would disagree with the notion that time is a separate dimension, I rather see 4 dimensional spacetime as an amalgamation of space and time.

8. Jul 1, 2008

### pmb_phy

The same thing can be said in non-relativistic mechanics with no mention of a fourth dimension
For what reason? Do you think that time does not fit any definition of dimension? In spacetime time is a dimension in that it is a number which is required to identify one event amoung many.

Pete

9. Jul 2, 2008

### MeJennifer

The elapsed time between two events is expressed in terms of four dimensions not just one.