throwaway_yy2Di
Joined 13 years ago
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Comment · 10 years ago
Comment · 10 years ago
Apropos, to anyone who wants to watch the live moves, with expert commentary, they are here (this is the defendant from the Reuters story):
https://chess24.com/en/read/news/chess24-win-moscow-case-ann...
https://www.youtube.com/channel/UCkTCNuQ2mGfW6-SpHpaze_g (direct link to livestream)
If you're looking for live computer engine lines, Steinar Gunderson offers that here, with 38 cores running Stockfish:
As well as PGN files (live-updated):
Comment · 10 years ago
Not my workaround:
http://spectrum.ieee.org/aerospace/space-flight/titan-callin...
http://descanso.jpl.nasa.gov/seminars/abstracts/viewgraphs/H...
This was an extremely serious bug in NASA/ESA's Cassini-Huygens probe, in the S-band link between Huygens (landing on Saturn's moon Titan) and Cassini (acting as radio relay).
It was a timing bug. There'd be a very high relative velocity between Cassini and Huygens, creating a significant (~2e-5) Doppler shift in the link. This shifted the frequency of the 2 GHz carrier (by 38 kHz). Likewise, it shifted the symbol rate of the 16 kbps bit stream (by 0.3 bps). The second effect was overlooked. On the demodulating end (Cassini), the bit-synchronizer expected the nominal bit rate, not the Doppler-shifted bit rate. Since its bandwidth was narrower than the 0.3 bps Doppler shift, it was unable to recognize frame syncs; this was proven in experiments post-launch. The parameter that set the bitrate was stored in non-modifiable firmware.
As it was when launched, Huygens would be unable to return any instrument data. For some context, this was the only probe that's ever visited Titan, at a cost of about $400 million.
The workaround
[spoiler]
The workaround was a major change in the orbit trajectory of Cassini (a $3 billion probe). Details aside, it set up an orbit geometry with this feature: at the time Huygens was descending in Titan's atmosphere, Cassini would be flying at a ~90° angle to their separation. The relative velocity was still 20,000 kph, but tangential velocity doesn't contribute to Doppler shift.
Comment · 10 years ago
Apropos, the Gaia space telescope's first data release is next week. It's an extremely large dataset of the kinematics (3d position + velocity) of Milky Way stars.
Comment · 10 years ago
...tidally locked, possibly losing their water and
atmosphere in tens or hundreds of millions of years.
Comment · 10 years ago
Here's a better answer on /r/askscience:
Can we directly image the planet from earth?
1. "The planet/star contrast is 10^-7 " This basically means
for every 10,000,000 photons from the star, we would measure
~ one from the planet.
2. "Current instrumentation using adaptive optics and
coronography on 10 m class telescopes (like Sphere on VLT or
Gemini Planetary Imager) aims at achieving a contrast of
10^-6 to 10^-7 at an angular resolution of 100-200 mas"
3. "The planet has a separation of 38 mas".
4. Therefore with the best planet imagers we cannot
currently directly image the planet. Our best hope is the
E-ELT which should have first light in 2024.
There's no known tractable way to solve chess. There's something like 10^120 move orders [0], and no known way to find perfect play without brute-forcing (almost) all of them. Chess engines can't solve to to the end of a game to see which moves are certain to win; they can only explore to a very shallow depth, and evaluate the horizon nodes by very human-like [1] approximate heuristics.
It looks perfect from a human PoV (the best human players have no chance of winning); but there's still an unimaginably large gulf between chess engines and mathematically perfect chess.
[0] https://en.wikipedia.org/wiki/Shannon_number
[1] https://github.com/official-stockfish/Stockfish/blob/master/...