Time a vector?

1. Aug 21, 2011

romsofia

Is time a vector?

I don't think so, because we can't go back in time therefore it can't follow vector rules.

However, I'm not sure this works in all cases (such as in a cases where v is close to c).

Thanks for the help.

2. Aug 21, 2011

BruceW

In relativity, time is one component of the spacetime 4-vector.
Also, it is theoretically possible to go meet your former self according to general relativity.

3. Aug 21, 2011

Naty1

You can make time a scalar or a vector in a particular theory...the test is whether such a formulation matches observations and leads to any predictions. Is it useful??

While time is a vector in relativity it is not in Newtonian physics.

A vector has magnitude and direction....it doesn't have to point everywhere nor is our ability to "go" with a vector a criteria....for example, you also cannot "go" where an acceleration vector does.

4. Aug 21, 2011

romsofia

Oh I think I've seen that somewhere, but I thought we took the time out. E.G. $${S(x,y,z,t)}$$ and then we did something like $${S(x,y,z)*e^{-i\omega t}}$$ but I doubt that is what you're talking about haha.

Anyway, thanks for the help!

A vector also has to follow basic laws (addition, subtraction, etc). If you can't go back in time, then you can never have a negative time value which is possible following the laws of subtraction.For example, $${C=B-A}$$ with $${B=1}$$ and $${A=2}$$ then $${C=-1}$$ which wouldn't make sense to me.

Anyways, thanks for your input and help!

5. Aug 21, 2011

BruceW

No problem. It looks like you're talking about some quantum energy eigenstate. This can't be done for a general quantum state. Also, I was talking about relativity, not quantum mechanics.
In relativity, we can talk about each spacetime event being specified by 4 components (i.e. a 4-vector). We only know which is the time component when we define it ourselves. So time is not a separate entity from space in relativity.

6. Aug 21, 2011

romsofia

Brain fart on my part haha, I guess when I was typing that I forgot that you were talking about general relativity >.<!

Thanks for all the help though, I have little knowledge of relativity so I guess I have to start studying some of it :D!

7. Oct 4, 2011

Staff: Mentor

The laws that a vector must satisfy are listed here.
http://en.wikipedia.org/wiki/Vector_space#Definition

There is no requirement that you be able to "go" backwards in time for time to be a vector. A negative time simply means that one thing happened earlier than another.