# Time vs Space

1. Mar 15, 2004

### cripkd

Did Einstein meant by space-time continuous that time is just another dimension, like the other 3?
If so, why are we experiencing this one that differently? (Should this have gone in the phylosophy section?)

2. Mar 15, 2004

### Severian596

First thing I think of is we have no influence over our location in time. It's decided for us by nature. We can influence our locaiton in 3-space.

3. Mar 15, 2004

### EL

At least Einstein ment that the dimensions of space and the dimension of time where connected and not independent of each other. I find it hard to put them on equal footing, but it´s a good question...

4. Mar 15, 2004

### pmb_phy

Mathematically? Yes. Physically? No.

5. Mar 15, 2004

### cripkd

Ok, then what is time physically ? :)
I know this is an OLD question, and i'm asking it rethoricaly. Could someone point me to some resources on what time is, other than specutlations, at least what modern physics considers it to be , today :)

6. Mar 15, 2004

### ahrkron

Staff Emeritus
Here's a nice essay from Lee Smolin (at the end, there is a little bio sketch of Smolin).

Just to add my own (short version of an) answer: we define time as that which is measured by clocks. It's flux depends on relative motion and gravity, and the process by which we accumulate information can only go in one direction with respect to that flux.

7. Mar 15, 2004

### cripkd

You know how when you have a circle and you take a straight line perpendicular on the circle, in it's center, and sliding the circle along the line produces a cilinder?
Well this is how i see time, it generates the 4 - dimensional universe, with the 3 spatial dimension sliding in one direction along the line and perceve this movement as passing of time.
In my vision the universe, if looked upon from outside the 4 dimensional space-time continuous, would look motionless, every object having 'motion trails' that are in fact it's states in time.

8. Mar 16, 2004

### DW

You mean continuum? It is "just" another dimention, but a timelike dimention differs from a spacelike dimention in that for displacement along the timelike direction $$ds^2$$ has an overall sign difference from a dispacement along a spacelike direction. So they are indeed both mathematically and physically different types of dimention.