[texhax] Space factor as dimen?

[Joel C. Salomon]

Joel C. Salomon wrote:
> I’m playing with amsthm, and want to define a theorem style like:
> 	Example:**To avoid lithobraking, most rockets…
> where the ‘**’ is the wide space TeX puts between sentences.
> 
> The eight argument to \newtheoremstyle is the “head space”; and I know I
> can give it an explicit (inter-word) space, ‘\newline’, or a dimension
> like 0.5em.  But what is the size of the inter-sentence space?

I found the word I needed---space factor.  To rephrase the question
above: can I supply a space factor to a macro expecting a dimen?
(Passing {\spacefactor3000} as the argument does not work.)

Failing that, how can I determine the default width of an inter-sentence
space?

—Joel Salomon