| Topic: |
Science > Physics |
| User: |
"Sam Wormley" |
| Date: |
01 Feb 2008 08:26:09 PM |
| Object: |
Constant failure |
Constant failure
Robert P Crease wonders if fundamental constants like π and <i>h</i> are the
most appropriate to use
http://physicsworld.com/cws/article/print/32679
.
|
|
| User: "Jim Black" |
|
| Title: Re: Constant failure |
02 Feb 2008 09:24:24 PM |
|
|
On Sat, 02 Feb 2008 02:26:09 GMT, Sam Wormley wrote:
Constant failure
Robert P Crease wonders if fundamental constants like ð and <i>h</i> are the
most appropriate to use
http://physicsworld.com/cws/article/print/32679
I agree that Planck's constant h was a suboptimal choice; that's why hbar
was introduced. Pi is also suboptimal, and if it weren't for the fact that
writing an extra 2 isn't much more trouble than writing an extra "/2pi", we
would probably have introduced a symbol for 2pi already.
I suggest pibar, a pi with an extra horizontal line drawn through it.
Cutely, it looks like two pi's superimposed with a slight vertical offset.
Crease uses psi in his article, but I wouldn't want to use that because it
clashes with other uses of psi, such as the wavefunction in quantum
mechanics. Palais, in
http://www.math.utah.edu/~palais/pi.pdf
uses two pi's with a horizontal offset rather than a vertical one. This is
also a reasonable choice, but I fear that it is more likely to be mistaken
for the original pi by a casual reader. Pibar looks funnier, and would be
more likely to be noticed.
Palais also brings up the point that a 2pi symbol would make angles
expressed in radians easier to understand. Ninety degrees becomes pibar/4,
readily interpretable as one-quarter of a full circle.
Moving the symbol out of the alphabet would have the additional advantage
of removing clashes with other uses of the letter pi, such as conjugate
momentum and the pion field. For example, equation (2.26) in Peskin and
Schroeder would go from starting with
pi(x) = integral d^3(p) / (2pi)^3 ...
to starting with
pi(x) = integral d^3(p) / pibar^3 ...
Plus, in multidimensional Fourier transforms like the equation mentioned
above, we save ourselves from not only writing a 2 but also from having to
write the opening and closing parentheses.
What do other readers think?
--
Jim E. Black (domain in headers)
How to filter out stupid arguments in 40tude Dialog:
!markread,ignore From "Name" +"<email address>"
[X] Watch/Ignore works on subthreads
.
|
|
|
|
| User: "Uncle Al" |
|
| Title: Re: Constant failure |
02 Feb 2008 10:55:23 AM |
|
|
Sam Wormley wrote:
Constant failure
Robert P Crease wonders if fundamental constants like π and <i>h</i> are the
most appropriate to use
http://physicsworld.com/cws/article/print/32679
Newton's G is by far the most beautiful because it cannot be
calculated. No aspect of classical or quantum physical theory derives
the strength of gravitational interaction. Newton's G, the coupling
constant, must be inserted by hand. It's a ***** to measure, too -
the least accurate of all natural constants by a half-dozen decimal
places.
Given that all other physical interactions can be ground out ab inito,
G is telling us something unpleasant.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/lajos.htm#a2
.
|
|
|
|
| User: "Army1987" |
|
| Title: Re: Constant failure |
03 Feb 2008 07:18:12 AM |
|
|
Sam Wormley wrote:
Constant failure
Robert P Crease wonders if fundamental constants like π and <i>h</i> are the
most appropriate to use
http://physicsworld.com/cws/article/print/32679
I also wander why permittivity is given a name and a symbol, as opposed to
its reciprocal. It appears in the denominator in most equations I can
think of. Yes, there are those for capacitance, but then, I can't see the
reason why capacitance is used instead of elastance, either.
--
Army1987 (Replace "NOSPAM" with "email")
.
|
|
|
| User: "finite guy" |
|
| Title: Re: Constant failure |
03 Feb 2008 08:28:33 AM |
|
|
On Feb 3, 10:18=A0pm, Army1987 <army1...@NOSPAM.it> wrote:
Sam Wormley wrote:
Constant failure
Robert P Crease wonders if fundamental constants like =F0 and <i>h</i> a=
re the
most appropriate to use
http://physicsworld.com/cws/article/print/32679
I also wander why permittivity is given a name and a symbol, as opposed to=
its reciprocal. It appears in the denominator in most equations I can
think of. Yes, there are those for capacitance, but then, I can't see the
reason why capacitance is used instead of elastance, either.
--
Army1987 (Replace "NOSPAM" with "email")
Why is pi? Not what is pi...
Is it possible to have a circle of finite quanta?
Thanks.
.
|
|
|
|
|
|
Related Articles |
|
|
