# How do you name

1. Nov 12, 2006

### bernhard.rothenstein

How do you name a physical quantity that can be defined at a given point in space: pointlike? local? Say energy density.

2. Nov 12, 2006

Staff Emeritus

Well it's a field. But what kind depends on the type of quantity. Spinor, scalar, tensor, density of weight d, etc.

3. Nov 12, 2006

### robphy

Do you actually mean something that can be defined "only at one point"?
Or something "distributional" (like a Dirac delta function)?

Do you have a specific detailed example?

4. Nov 12, 2006

### pmb_phy

It seems to be way you use the term "write" It seems okay. Folks you might use the term "word."

Pete

5. Nov 12, 2006

### bernhard.rothenstein

point like? punctual?

I mean density of energy which can be defined in the case of an uniform distribution as ro=m/V but as ro=dm/dV in the case of a nonuniform distribution having well defined magnitudes at different points in space. Do you say that it is a pointlike or punctual physical quantity.
Thanks to al who have answered my question.

6. Nov 12, 2006

### Staff: Mentor

When we have a time-varying quantity and we want to refer specifically to its value at a certain point in time, we often use the word "instantaneous". Are you looking for a similar word to refer to the value of a spatially-varying quantity, at a particular point in space?

In that case, I think the best word would probably be "local", e.g. "local energy density," as opposed to the "average energy density" over a region of space.