20150204

Wed Feb 4 07:30:38 EST 2015 Slept OK. A little more snow. Goals: Work: - Finish at least one more cubicle move today Done. - Work on (finish?) budget spreadsheet No. - Review VM guest snapshot backups and VM host disk space Done. More engineering decisions to make, though. Stayed late to test check scanning. Home: Nothing. Picked up a few groceries on the way home. Questions: - What do we see when we see electricity? Why does lightning produce visible light? Or, what is thermal radiation (is it only visible thermal radiation)? A: Both incandescence (atmospheric gases glowing with heat) and luminescence (photons released when excited electrons drop back to their ground state). Incandescence is hot because the agitation of atoms, while luminescence is cold because the excitation of the electrons do not necessarily correspond to any agitation of their atoms. Incandescence is atoms rubbing against each other; luminescence is electrons within atoms dropping. http://www1.union.edu/newmanj/Physics100/Light%20Production/producing_light.htm http://micro.magnet.fsu.edu/primer/lightandcolor/lightsourcesintro.html When a fire burns, chemical energy is released in the form of heat and light. The burning fuel, whether it is grass, wood, oil, or some other combustible material, emits gases that are heated by the enormous chemical energy generated during combustion, making atoms in the gas glow or incandesce. Electrons within the gas atoms are promoted to higher energy levels by the heat, and light is released in the form of photons when the electrons relax to their ground state. The color of a flame is an indication of the temperature and how much energy is being released. http://theengineerspulse.blogspot.com/2012/01/why-does-lightning-appear-blue-and.html The reason that lightning is visible is due to both incandescence and luminescence. Incandescence occurs due to the locally high temperature of air, which emits a blue-white glow. The luminescence is a bit more complex. The air in the atmosphere consists largely of nitrogen gas molecules. The rapid flow of energy of the electrical discharge causes the electrons of the nitrogen molecules to move to higher energy states. However, this state is very temporary - the molecules return to their original state soon after. And it is this change of state that emits the distinctive blue-white colour that we associate with lightning, and electricity in general. As such, the visual evidence of lightning is not the charge itself, but rather its effect on the air that it travels through. And the same is true with the static electricity we see under our sheets on cold winter nights. Here, we do not have the extreme high temperature that we had with the lightning (no incandescence), so the colour that manifests is due exclusively to the luminescence described above. It turns out that those "sparks" travelling along your pajamas that freaked you out as a kid were just the flashing of nitrogen molecules. http://www.webexhibits.org/causesofcolor/4.html While the vivid white light we associate with lightning is an example of incandescence, with a temperature in the order of 30,000 K, its colors also stem from gas excitations - light emitted through the excitation of gas molecules in the atmosphere. Gas excitations are a form of luminescence, photons of light being emitted as excited electrons drop back to their initial energy state. Unlike incandescence, luminescence may occur at low temperatures. - Why aren't password managers implemented as a basic network service? That's sort of what OAuth and OpenID were trying to do. OAuth and OpenID rely on the service provider to implement them. Adoption will never be universal, so they're not a substitute for password managers. Why not self-hosted services like LastPass? - It becomes very important to get security of the password store right, which might be difficult for any individual user. - Difficulty of security on the wire, SSL certs, etc. - There's probably no standard for communication between e.g. a browser plug-in and the password service. - There are desktop password managers like Password Gorilla. Even if the user stores the pw file somewhere like Dropbox, it's still not really a network service. Also, I don't think desktop clients generally have browser plug-ins. - What would be the advantage of password manager as network service? - Not necessarily relying on a third party - What about in an enterprise/corporate environment? - With some sort of key escrow system, it would be possible for admins in a corporate setting to help users recover encrypted password stores https://www.schneier.com/paper-key-escrow.html

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