On Sun, 17 Oct 2021 09:37:37 -0700, Paul S Person
<psperson1@ix.netcom.invalid> wrote:

>>Pi is NOT a physical constant; it is a mathematical construct that is
>>useful. The Fine-Structural constant, see
>>(<https://en.wikipedia.org/wiki/Fine-structure_constant>) is one of the
>>physical constants being referred to.
>
>Thanks for your input. But the point (such as it is) remains.
>
>And how many binary digits do we know it to?
>
>And where would changing flipping one actually produce a known effect?
>
>Do /any/ of these constants have a closed form? That is, an exact
>value that can be expressed as a finite number?
>
>If they could be altered, would any of them be quantized or would they
>all be continuous?

I have no idea but have heard past a billion digits.

I've heard the main reason for doing these computations is not so much
for their own sakes but as a way of performance testing new compilers.

On Monday, October 18, 2021 at 9:52:31 AM UTC-6, Paul S Person wrote:
> On Sun, 17 Oct 2021 21:36:58 -0700 (PDT), Moriarty
> <blu...@ivillage.com> wrote:

> >Some have an exact value, but that's by definition. For example, the speed of light. The others are measured and, of course, have margins of error.

> So ... some measure (presumably of distance, since speed is
> distance/time) is /defined in terms/ of the speed of light?

Basically, what happened was this:

It used to be that the second was defined in terms of the frequency of microwave
radiation from one particular substance...

and the metre was defined in terms of the wavelength of light from another substance...

since it was easier to feed microwave radiatiion into the electronic circuits of an atomic
clock,

while it was easier to measure distances using the interference fringes of light.

But then somebody did an experiment to determine the speed of light by comparing
these two types of electromagnetic radiation, and this was so embarassing to the
physical community that they dropped the old definition of the metre, and now
both the metre and the second are defined from the same form of radiation, by using
a defined value for the speed of light in metres per second and the old definition of
the second which still stands.

John Savard