
An Exact Value for the Planck Constant: Why Reaching It Took 100 Years - JulienRbrt
http://blog.wolfram.com/2016/05/19/an-exact-value-for-the-planck-constant-why-reaching-it-took-100-years/
======
cdumler
Glancing through it, it almost appears that it's almost copy and paste. It has
so many tangents and subject splices, it is hard to follow.

It appears to be arguing that the Planck constant is defined partially by
mass, which has never had an high-precision value SI unit. The Avogadro
project has determined a high-precision definition the Avogadro constant. The
Rydberg constant is known to high precision; therefore, the two can be used to
together to find a high-precision value of the Planck constant. Also, once a
fixed definition of mass through physical constants is made, we will have an
exact definition of Plank constant.

------
Someone
_" in 1889 the Romanian prototype was already 953 mg lighter than the
international prototype kilogram"_

Is that correct, or should that be 953 μg? I find it hard to believe that a
carefully kept reference kilogram designed to keep its mass would lose almost
a gram in a century.

μg Also seems more in line with what Wikipedia writes
([https://en.m.wikipedia.org/wiki/Kilogram#Stability_of_the_in...](https://en.m.wikipedia.org/wiki/Kilogram#Stability_of_the_international_prototype_kilogram))

------
gsmethells
If there ever was a need for a TL;DR, then this is it. Anyone care to take a
crack at it?

~~~
rwallace
It's an enchanting, well-written essay on the history of an area of science
few people ever think about, a window into the past, containing quite a few
things I didn't know before, and along the way a showcase of some pretty neat
things Mathematica can do.

No, it doesn't need a tl;dr. It doesn't contain any data you're going to
personally need today or tomorrow. It falls into the categories of
intellectual curiosity and general education. If that's not your dish, skip it
and move on.

But I am reminded of a Lewis Carroll quote:

 _" No, no!" she broke in merrily. "I didn't mean our Literature! We are quite
abnormal. But the booklets--the little thrilling romances, where the Murder
comes at page fifteen, and the Wedding at page forty--surely they are due to
Steam?"

"And when we travel by Electricity if I may venture to develop your theory we
shall have leaflets instead of booklets, and the Murder and the Wedding will
come on the same page."_

Successful prediction.

~~~
euyyn
I mean, if you weren't going to tell the parent what it wanted, as others did,
why bother?

------
outworlder
Interesting advertising. It shouldn't be that long though, unless they expect
us to spend 100 years too.

------
domdip
This is unreadable.

~~~
scottshea
It lost me with the opening spoof (?) of Sympathy for the Devil. Love the song
but not remotely needed in the article.

------
brianpgordon
Wow, is this an entire year's work? It just keeps going and going, and going.

