3 ms·

This is an interesting question. For some reason, the European scientific culture to question everything and preferring “useful knowledge” apparently did not t

This is an interesting question. For some reason, the European scientific culture to question everything and preferring “useful knowledge” apparently did not transfer to Brazil with the Portugese. Here's an excerpt from Surely You’re Joking, Mr. Feynman!, discussing education in Brazil which I think is relevant: http://v.cx/2010/04/feynman-brazil-education http://v.cx/2010/04/feynman-brazil-education

rmk 10y ago
Thanks for that excerpt. It was an entertaining read!
- Animats 10y ago
  I remember that section from decades ago, mostly because of Feynman writing: “When you take a lump of sugar and crush it with a pair of pliers in the dark, you can see a bluish flash. Some other crystals do that too. Nobody knows why. The phenomenon is called "triboluminescence.'". Reading that, I thought "could it be lasing?". A laser is two parallel mirrors around a medium with electrons in an excited state. Squeezing a crystal will produce electrical energy by piezoelectricity. Crushing a crystal will produce parallel planes, at least momentarily. So the preconditions for lasing exist. This is still an open question today. Lasing of crystals under pressure may have been observed in some exotic materials.[1] But it doesn't seem to be the main light-emission mechanism in triboluminescence. [1] http://adsabs.harvard.edu/abs/2002ApPhL..81..460R http://adsabs.harvard.edu/abs/2002ApPhL..81..460R
  - metafunctor 10y ago
    A very long time ago, I read about this and experimented in a dark toilet after sunset. I did get the flash, but it wasn't terribly easy to get a flash with the small sugar crystals available to me at the time. The next day, there were ants after all that sugar on the toilet floor (also featured in Feynman's book), leading to further experiments ferrying ants :)

3 ms·

This is an interesting question. For some reason, the European scientific culture to question everything and preferring “useful knowledge” apparently did not t

by metafunctor 10y ago

rmk 10y ago
Thanks for that excerpt. It was an entertaining read!
- Animats 10y ago
  I remember that section from decades ago, mostly because of Feynman writing: “When you take a lump of sugar and crush it with a pair of pliers in the dark, you can see a bluish flash. Some other crystals do that too. Nobody knows why. The phenomenon is called "triboluminescence.'". Reading that, I thought "could it be lasing?". A laser is two parallel mirrors around a medium with electrons in an excited state. Squeezing a crystal will produce electrical energy by piezoelectricity. Crushing a crystal will produce parallel planes, at least momentarily. So the preconditions for lasing exist. This is still an open question today. Lasing of crystals under pressure may have been observed in some exotic materials.[1] But it doesn't seem to be the main light-emission mechanism in triboluminescence. [1] http://adsabs.harvard.edu/abs/2002ApPhL..81..460R http://adsabs.harvard.edu/abs/2002ApPhL..81..460R
  - metafunctor 10y ago
    A very long time ago, I read about this and experimented in a dark toilet after sunset. I did get the flash, but it wasn't terribly easy to get a flash with the small sugar crystals available to me at the time. The next day, there were ants after all that sugar on the toilet floor (also featured in Feynman's book), leading to further experiments ferrying ants :)