Thursday, July 22
Today on Pixy's Science Theatre: Tales of the Very Small!
A micron, or micrometre, is one millionth of a metre, 10-6 m. A typical human hair is about 80 microns thick (the range is rather large, from 18 to 180 microns). A human red blood cell is 6 to 8 microns across; the average bacterium is between 1 and 10 microns. The wavelength of visible light is around half a micron - ranging from 0.38 microns for violet to 0.74 microns for red. The smallest features of today's computer chips are just 0.09 microns wide.
An Ångström is much smaller, one ten-thousandth of a micron, one ten-billionth of a metre, 10-10 m. Atoms are around one Ångström wide - half an Ångström for hydrogen, the smallest of all atoms. X-rays have a wavelength of around an Ångström. The double-helix of DNA is about 20 Ångströms across.
The Fermi is far smaller still, one one-hundred-thousandth of an Ångström, one quadrillionth of a metre, 10-15 m. A proton or neutron is about one Fermi in diameter.
The Planck Length is really ridiculously small: about a tenth of a billionth of a quadrillionth of a Fermi, 1.6 x 10-35 m. According to current theoretical physics, that's as small as you can go: any distance smaller than a Planck Length doesn't actually exist.
Thursday, July 15
Oh look, a new urgent security update!
Really, the difference between open-source software and closed-source software is not the number of bugs, but the manner in which fixes are announced. Err, and the price too.
But this time I managed to completely rebuild MuNu's Apache server with all its attentand modulary without breaking anything! As far as I know...
Update: DOH! Why the hell does the Apache install script in CPanel reset the permissions on everyone's home directory, forcing me to manually correct the settings for 113 users?
Wednesday, July 14
The database archive server failed a perfectly good disk out of the RAID-5 set. A quick raidhotremove and a raidhotadd - and a 20-hour resync - and it's back again. It would be better, though, if Linux didn't fail disks out of RAID-5 volumes every time a gnat farts in the computer room.
Monday, July 12
Well, that was weird. No mouse, reboot, no Windows. Boot from CD, chkdsk, reboot, no windows. Put CD back in, reboot... Windows. Eh.
My mouse - my shiny 7-button Logitech MX700 cordless optical mouse - no longer mouses. Woe!
Saturday, July 10
> Theories are wonderful things. IIRC, there is some speculation that
> the photon possesses a (albeit small) nonzero mass. Also, there is
> the notion that all particles have what is called a "supersymnmetric
> dual", speculatively named the photino, neutralino, and gravitino for
> the photon, neutrino, and graviton respectively.
And squarks, sleptons, ... gluinos and higgsinos. Actually, the
supersymmetric dual of the neutrino is the sneutrino. The neutralino is
a combination of, I think, the Zino, the photino and maybe a Higgsino
that ends up being the lightest supersymmetric particle. In a number of
theories, this particle cannot decay and turns out the be a great
candidate for dark matter.
(Dwight Thieme and Aaron Bergman on rec.arts.sf.science)
Thursday, July 08
I have 86GB of documents here in a hundred different proprietary formats, and I am searching them for the word "pelican".
Wednesday, July 07
The good thing about computers is if you think something is true but you're not 100% sure, you can quickly spot-check a few million examples.
Well, it's useful in my line of work, anyway.
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