Archive for April, 2008

Command Line History

Thursday, April 17th, 2008

Here’s a fun little game that Brandon linked to me from Rail Spikes. See what you’ve been running from the command line recently!

matt@Valhalla:~$ history 1000 | awk '{a[$2]++}END{for(i in a){print a[i] ” ” i}}’ | sort -rn | head
111 ls
71 /Applications/Firefox.app/Contents/MacOS/firefox
67 cd
28 tar
25 rm
25 latex
22 exit
22 dvipdft
20 vi
16 mv

Incidentally I’m running Firefox from the command line in order to switch user profiles (they’re still there from the old Mozilla days, but switching is a bit of a secret now — run firefox -ProfileManager)

Quantum Graffiti

Wednesday, April 2nd, 2008

Quantum Mechanics may be the ultimate mindfuck. Einstein was no fan — he famously wrote “God does not throw dice,” referring to his distaste for the statistical formulation underlying quantum theory. Despite his misgivings, quantum physics has proven effective at describing all manner of natural phenomena since its formulation in the early 20th century. That said, the formalism does lead to some rather odd or paradoxical conclusions.

Not least among these is the notion of Quantum Entanglement — that observable qualities of systems may be statistically correlated, even though the systems may be separated by vast spatial distances. An example is a pair of entangled electrons — one will have spin up, one spin down, but the individual states are indeterminate until a measurement is made. However, once the spin of one electron is measured, the spin of the other will become determinate instantaneously, and more importantly, superluminally. Einstein labeled this theoretical phenomenon “Spukhafte Fernwirkung” — “spooky action at a distance.”

These graffiti, placed on opposite ends of a bridge, embody the notion of entangled states, each with Einstein’s appellation and a measured spin wavefunction — up for Alice and down for Bob, whose wavefunction has collapsed once Alice makes her measurement.

Alice's entangled stateBob's entangled state

For more on entanglement and Einstein’s view, I also suggest reading about the EPR Paradox.