cperciva

35 ms·

661.
by cperciva 3y ago
The superconductor itself would be 7.44% gold, but the wire would probably be much less -- superconducting tape isn't particularly strong so it will probably be wrapped up in layers of insulator and support wires.
662.
by cperciva 3y ago
Might take a while. Tarsnap has never had an employee without a doctorate. She's a very bright girl but I'll be surprised if she gets her doctorate before 2040.
663.
by cperciva 3y ago
For the record, I'm happy to live in a world where rsync.net exists. I've pointed quite a few customers in your direction over the years, when tarsnap hasn't been suitable for their needs for a variety of reasons.
664.
by cperciva 3y ago
Yep! I've been meaning to do it for a while but there was always something higher priority... I didn't realize until this outage that it had been almost a decade since I had tested it. Rehearsing this annually is definitely going
665.
by cperciva 3y ago
Don't worry, I had a couple naps in there. "This seems to be running smoothly but it will take several more hours; I'll set my alarm to wake me up in two hours and have a nap" is part of why I didn't notice the sec
666.
by cperciva 3y ago
Pretty sure his brother works on tarsnap too. Yes, I hired him in 2015 IIRC. If you look at tarsnap's GitHub you'll see a lot of commits from gperciva.
667.
by cperciva 3y ago
Thanks, I did! My long suffering wife was up at 3:30 though. :-(
668.
by cperciva 3y ago
There's a continual background cleaning process which depends on the amount of storage which can be reclaimed -- there's a tradeoff between cleaning too slowly (and paying for wasted storage) and cleaning too fast (and paying for
669.
by cperciva 3y ago
Yes, rehearsing the process every year is the main lesson learned. Sorry, it was getting late and I wanted to get the email out so I cut it short.
670.
by cperciva 3y ago
She's generally a wonderful girl. Right now she's dealing with her second molars coming out and just picked up a cold though, which is throwing off her sleep schedule.
671.
by cperciva 3y ago
Yeah, I was going to do that but it was getting late, I wanted to get some sleep, and the post-mortem had already been waiting far too long to be sent out. The main lesson learned was "rehearse this process at least once a year".
672.
by cperciva 3y ago
blinks Ok, I really wasn't expecting this to land at the top of HN. I'd love to stick around to answer any questions people have, but it's 10PM and my toddler decided to go to bed at 5PM... so if I'm lucky I can get a
673.
by cperciva 3y ago
Not necessarily. The "strained crystal" approach probably extends to other elements; mixing Pb and Cu works well since there's a large difference in their sizes, but rare earths might work just as well as Pb.
674.
by cperciva 3y ago
With room temperature superconductivity doesn't it become possible to turn the magnet on and off far more easily? MRIs would be much safer if they were only energized during the actual imaging process.
675.
by cperciva 3y ago
If "social contacts made through your membership in the family" are covered by non-disclosure/non-solicitation, conceivably an ex-employee could be liable for damages? I agree that "withholding pay" is not the answe
676.
by cperciva 3y ago
The joke in the airline industry is that Canada doesn't have great aircraft pilots, but we have the world's best glider pilots.
677.
by cperciva 3y ago
I've never heard anyone say "mathematics are" The four mathematics are arithmetic, geometry, music, and astronomy.
678.
by cperciva 3y ago
No process has yet been observed that violates the conservation of baryon number, but the search continues. There is strong evidence that the big bang is such a process, but perhaps the author doesn't consider it to have been observ
679.
by cperciva 3y ago
To be fair, I wasn't just procrastinating from writing; I was also dealing with being diagnosed with a life-threatening illness. I semi-officially took a retroactive leave of absence for a term (I was a bit behind schedule, mentioned
680.
by cperciva 3y ago
Doesn't everyone spend a couple weeks figuring out their latex template?
681.
by cperciva 3y ago
When I was trying to avoid working on my thesis I wrote FreeBSD Update and bsdiff.
682.
by cperciva 3y ago
It already stands for Executive Director and Early Death. It's possible that the ED of an ED had an ED which led to him suffering from ED and ultimately having an ED.
683.
by cperciva 3y ago
See also kangaroos armed with stinger missiles: https://www.snopes.com/fact-check/shoot-me-kangaroo-down-spo...
684.
by cperciva 3y ago
Would be great for generator. That was my first thought too -- this design seems simpler and correspondingly less prone to failure than most engines, which would make it well suited for emergency use.
685.
by cperciva 3y ago
L4 and L5 are "stable" -- but of course on timescales of billions of years even Earth's orbit isn't guaranteed to be stable.
686.
by cperciva 3y ago
I (a) proved bounds, and (b) showed that those bounds were tight by constructing inputs which came close to the error bounds. The "empirical bounds" demonstrably don't work for some inputs.
687.
by cperciva 3y ago
Doing an FFT with integer math means doing it in a ring -- and thus dealing with modular reduction. Using complex floating-point math the "modular reduction" comes for free thanks to w^N=1. I would have to write some code to conf
688.
by cperciva 3y ago
Right, I didn't think people would actually want to read the paper; I just wanted to make the point that, rather than being difficult, this was solved over 20 years ago. (And I was an undergrad at the time!)
689.
by cperciva 3y ago
It is difficult to prove that round-off error won't affect the results. Colin Percival, Rapid multiplication modulo the sum and difference of highly composite numbers, Mathematics of Computation, Volume 72, Number 241, Pages 387-395,
690.
by cperciva 3y ago
It's not necessarily a matter of not wanting to share space. Some birds instinctively build nests on cliffs, but when their instincts drive them to nest on the side of skyscrapers, their young end up falling to their deaths since skys

More ›