Re: Semi OT Grace Hopper lecture

On Fri, 8 Nov 2024 21:25:49 +0000, Lawrence D'Oliveiro wrote:

On Fri, 8 Nov 2024 11:15:50 +0100, Terje Mathisen wrote:
>

The standard paper size available in all printers and copiers is of
course A4, and that A4 sheet is exactly(*) one nanosecond tall (29.97
cm) as well as one nanosecond when travelling inside an optical fiber
wide!

>
Hey, I never noticed that. Proof, if any were needed, that international
standard paper sizes and units of measurement were given to us by the
gods ...
>
By the way, that must mean the refractive index of optical fibre is
close
to 1.4. Is that plastic? Because glass would be closer to 1.5, wouldn’t
it?

You can make glass (amorphous si-dioxide) in refractive indexes from
about 1.1 through about 1.85; there is a special kind of glass with
RI = 2.0 used to make the reflective paint on street signs. {{A round
ball with RI = 2.0, reflects incident light back where it came from.}}

Terje (*) Within your ability to measure with a ruler, or a paper
supplier to cut.

>
Yes, the size of a sheet of paper can vary quite appreciably (by as much
as a few percent), depending on the humidity particularly.