# Frame of reference

1. Aug 24, 2004

### eljose79

given a frame of reference s In General Relativity in wich you meassure an interval of space dx, could we have another frame Sso the observer in that Ssee that dx observed in S as a time interval dt?

2. Aug 24, 2004

### robphy

"Could [in a small neighborhood] a displacement interval be determined to be spacelike (i.e., have negative square-norm) to one observer but timelike (i.e., have positive square-norm) to another observer?",
The character of the displacement interval is determined by the metric tensor at the event, not by the choice an observer at that event.

3. Aug 24, 2004

### pervect

Staff Emeritus
I don't think so. A spacelike interval will remain spacelike for all observers, a timlike interval will remain timelike.

4. Aug 25, 2004

### LURCH

In anither thread (about Black Holes) somone mentioned reading that, at the EH, spacelike worldlines become timelike and vise-versa. Is this incorrect?

5. Aug 25, 2004