I am French, and I have never heard of using the point to separate thousands of hundreds, but a space is fine (11 500 and not 11.500), as you can see if you compare the "million" article from wikipedia in
french and
english.
Anyway, the International Bureau of Weights and Measures, in their22nd General Conference, decided that:
"the dot (point on the line) [is used] as the decimal marker in all the English language versions of its publications, including the English text of the SI Brochure (the definitive international reference on the SI), with the comma (on the line) remaining the decimal marker in all of its French language publications"
And from the 7th General Conference which was held in 1948:
"Numbers may be divided in groups of three in order to facilitate reading; neither dots nor commas are ever inserted in the spaces between groups."
Those familiar with scientific publications will also not that those recommandations are enforced by editors, even american ones, because those aim an international audience. Now, you do what you want inside your country.