I was interested to note the use of attoseconds and yoctoseconds in an article
in the 2009 Dec. issue of Physics Today, a publication of the American
Institute of Physics. I don't think I've seen these SI prefixes used before
(except in our metric discussions).
Here are excerpts from the article:
Headline:
"Yoctosecond light pulses from quark-gluon plasmas"
Excerpts:
"In recent years, photon pulses in the attosecond (10^-18 s) regime have
been precisely engineered and are being increasingly put to work ... "
"Prompt gamma rays in the GeV range ... would exit the QGP in at most a few
yoctoseconds (10^-24 s)."
I think it is interesting to note that the author clarified the meaning of the
attosecond and the yoctosecond by including a parenthetical equivalence in
seconds. The author did not report individual results in attoseconds or
yoctoseconds and therefore did not have an opportunity to use the SI symbols of
those two units.
(I was confused by the abbreviation QGP. I wish it had been explained in the
clear way that the size of the attosecond and yocotsecond were. I'm guessing
QGP means Quark-Gluon Plasma.)
It is also worthy of note that the GeV (gigaelectronvolts) was used as the
energy unit. In this type of work, there are valid reasons why joules cannot be
used; basically, they don't know precisely how many gigaelectronvolts there are
in a joule. That is why the GeV (and eV, keV and MeV) are permitted for use
with SI.
(I'm sorry that I could not reliably produce exponents in this email message,
which is why I had to resort to the form using the caret mark, thus: 10^-24.
The article, as printed, used the preferred form of a ten with the proper power
shown as a superscript.)
Regards,
Bill Hooper
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