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Anders Sandberg
Academic jack-of-all-trades.
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Anders Sandberg 3 h
Odgovor korisniku/ci @Eorlingur
I suspect there is a lot of ways of influencing it. Temperature seems likely. I was told one might be able to do it by allowing spins to interact with a "spin reservoir". Magnetic fields can also change things:
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Anders Sandberg 3 h
Odgovor korisniku/ci @krfsm
Yes, shirts are often fluorescent since it makes them look whiter in outdoor light (and nightclubs). Dyes like marker pens are also often very fluorescent to truly highlight text. Makes sense for hair too.
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Anders Sandberg 3 h
Odgovor korisniku/ci @anderssandberg
Phosphorescence is more rare. Most glow-in-dark light is chemiluminescence, where some reaction powers the light, or even fluorescence due to particle radiation, as in old radium watches.
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Anders Sandberg 3 h
Odgovor korisniku/ci @anderssandberg
There is a lot more fluorescence going on than one might think. In my office I noticed fluorescent paper labels, cables, & a connector on a brain-pacemaker. I did not see it on banana spots, since my bananas were not ripe enough:
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Anders Sandberg 3 h
Odgovor korisniku/ci @anderssandberg
Why "triplet"? Originally the name is from spectroscopy, where it shows up as three spectral lines. There are doublet states (one unpaired electron) and the usual singlet states (where all the electrons are happily paired up).
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Anders Sandberg 3 h
Odgovor korisniku/ci @anderssandberg
The result is that the transition requires a simultaneous spin flip and energy drop, which is unlikely. Hence the electron loiters in the triplet state like a drunk fumbling with their keys as they try to unlock their door. Eventually the spin flips and it gets in.
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Anders Sandberg 3 h
Odgovor korisniku/ci @anderssandberg
The reason is electron spin. At the start the electron shares energy level with another electron with opposite spin. During the intersystem transition to the triplet state it flips spin. Now it is not allowed to jump down to its old place, since the 2 must have opposite spins.
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Anders Sandberg 3 h
Odgovor korisniku/ci @anderssandberg
The vial contains strontium aluminate. It starts the same, but then the electron gets trapped in a "triplet state" where the drop back down is harder (a "forbidden transition") and it remains there for a long time (up to hours) until it drops, releasing light.
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Anders Sandberg 3 h
Odgovor korisniku/ci @anderssandberg
The test tube has pieces of uranium glass, containing some U2O3. When hit by a UV photon, electrons jump up to a high energy state, lose some energy through a few small jumps, and then drop back down, releasing a longer wavelength (=visible) photon.
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Anders Sandberg 3 h
Friday physics fun: here are two yellowish solids. I shine UV light on them, they respond by shining green back. Afterwards one of the keeps on shining. What is going on? Fluorescence and phosphorescence.
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Anders Sandberg proslijedio/la je tweet
Gurwinder 18 h
MEGATHREAD TIME: In 40 tweets I will describe 40 powerful concepts for understanding the world. Some are complex so forgive me for oversimplifying, but the main purpose is to incite curiosity. Okay, here we go:
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Anders Sandberg proslijedio/la je tweet
Future of Humanity Institute 7 h
We are relaunching our AI alignment visitor program for 2020. If you're interested in working on AI alignment using tools from causal inference, general RL, or value learning then we'd love to hear from you: . The deadline for summer visitors is Feb 28.
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Anders Sandberg 17 h
Odgovor korisniku/ci @jasoncrawford
I wonder about the setting up of colonies. Clearly profitable in some cases, but also required significant investment.
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Anders Sandberg 17 h
Odgovor korisniku/ci @nyrath
Levi 1991 (eq 8) gives a relationship between speed and maximal allowed heating: The temperature seems to increase with the cube of the speed if everything else is constant. Superconductors avoid this, but have critical field and current.
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Anders Sandberg 6. velj
The awkward side of cheap rocketry.
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Anders Sandberg 6. velj
Odgovor korisniku/ci @Robotbeat @lsparrish i 12 ostali
Awesome!
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Anders Sandberg 6. velj
Odgovor korisniku/ci @Robotbeat @lsparrish i 12 ostali
Any pointer to this? Sounds interesting.
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Anders Sandberg 6. velj
Odgovor korisniku/ci @NickSzabo4 @jamesgiammona
Spreading civilization seeds around might just be a way of getting platforms on which to trade/think/whatever. Once the open source platform is running you might show up with your encrypted mind and business.
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Anders Sandberg 6. velj
Odgovor korisniku/ci @redcar_tenken @nyrath i 10 ostali
Tricky, since it is about three chapters in my book manuscript. But I am seriously thinking of making it a course at Oxford and record it.
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Anders Sandberg 6. velj
Odgovor korisniku/ci @hkjn @kanzure i 11 ostali
Advanced dependency graphs likely imply slow production, since there will be a long critical path - it is not just matter/information trade-off but also a time trade-off. MNT may "cheat" by making many things massively parallel, hiding the complexity to some extent.
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