Is Light-Like an Appropriate Term in Minkowski Space Terminology?

[actionintegral]

Hey friends,

When using phrases such as time-like and space-like, is it proper form to use the phrase light-like? Or is there a more professional expression?

 

[HallsofIvy]

"Space" and "time" are dimensions so it makes sense to talk about "space-like" and "time-like" regions of Minkowski space. Light is not a dimension and so there is no such thing as a "light-like" region. You may be thinking of a "light-path", the path light would follow, which is the boundary between "space-like" and "time-like" regions.

 

[actionintegral]

You may be thinking of a "light-path",

What if I said:

The set of events between event A and event B is timelike.
The set of events between event A and event C is spacelike.
The set of events between event A and event D is a light-path.

Is that the way "it" is said?

 

[nakurusil]

Hey friends,

When using phrases such as time-like and space-like, is it proper form to use the phrase light-like? Or is there a more professional expression?

You can find this expressions in older books , like Tolman's when it comes to describing the metric being >0, <0 and exactly 0.

 

[robphy]

Timelike, Spacelike, and Lightlike (or Null) are still in common use.
They are used to describe the nature of the causal relation between a pair of events in spacetime. (Example: Event A is lightlike-related to Event B.) They are also used to describe the sign of the Minkowski square-norm of a 4-vector. A lightlike (or null) vector has square-norm equal to zero, without the vector itself necessarily being the zero vector.

 

[pervect]

Hey friends,

When using phrases such as time-like and space-like, is it proper form to use the phrase light-like? Or is there a more professional expression?

I would personally suggest space-like, time-like, and null. As in "space-like geodesics, time-like geodesics, null geodesics". If you were talking about intervals, it would be space-like intervals, time-like intervals, and null intervals. (I haven't seen "null interval" actually used much, so "light-like" interval might be just as good.)

 

[Thrice]

Yeah I always heard it as null.

 

[Meir Achuz]

Hey friends,

When using phrases such as time-like and space-like, is it proper form to use the phrase light-like? Or is there a more professional expression?

I think "light-like" is OK to describe an interval on the light cone.
It is no better or worse that T-L or S-L, and consistent with their usage.