Re: Data types in physics

Boo <reply_to_group_not_me@xxxxxxxxxxxxxxxxxxx> wrote:

I may have been mislead by sensationalism, but I recall a report a few
weeks ago that the various international kilogram platinum-iridium
masses have been showing an unexplained divergence when compared with
each other.

Out of interest can anyone tell me why they use platinum-iridium for reference
masses ? I assume it has good oxidation characteristics but is the any other
reason for the ue of this material ?

Resistance to wear.

Also, do they keep them under a vacuum ?

<http://www.bipm.org/en/scientific/mass/prototype.html>
says it all,

Jan

.