throwaway_yy2Di

10 ms·

61.
by throwaway_yy2Di 11y ago
"Only slightly more seriously, it would be very impressive if they could pull it off, but having seen the deployment of Iridium (66), GPS (32), GLONASS (24) , and Galileo (30) it doesn't seem like we have a non-
62.
Xkcd #1537: “Types”(xkcd.com)
22 points by throwaway_yy2Di 11y ago|1 comments
63.
by throwaway_yy2Di 11y ago
Here you go, https://i.imgur.com/Bgttnqh.png
64.
by throwaway_yy2Di 11y ago
I don't think that's ruthenium -- that graph has a gap at technetium (Z=43), which has no long-lived isotopes. The line actually joins Z=42 and Z=44. (Might also be confusing that Sn (Z=50) is labelled at the wrong place (Z=48)).
65.
by throwaway_yy2Di 11y ago
It means 96% of the uranium fuel undergoes fission (gets its nuclear potential energy converted to heat). When they separate out fission products (waste) by chemical processing, about 4% of the fuel gets dragged into the waste stream. It lo
66.
by throwaway_yy2Di 11y ago
The original article, by Thomas Oléron Evans [0], does something similar. I made a graph of it here. It's a heuristic estimate of the expected number of integers that satisfy the property for bases (2..b), as a function of b. https:
67.
by throwaway_yy2Di 11y ago
There's two other differences you'd need to account for: * One Pu-238 nucleus weighs 238 amu; a triton only weighs 3 amu * Tritium decays 7 times faster -- a 12.32 year half-life, vs. 87.7 years for Pu-238 Put together, the specif
68.
by throwaway_yy2Di 12y ago
In practice, the ΔV differences are actually way smaller than that chart suggests. Those figures are for direct transfers (per the legend). But if you allow indirect trajectories with gravity assists [0], that makes things drastically cheap
69.
by throwaway_yy2Di 12y ago
Related, this came up in yesterday's thread about Graham's number: http://djm.cc/bignum-results.txt https://news.ycombinator.com/item?id=9054274
70.
by throwaway_yy2Di 12y ago
This paper says the downlink uses a rate 1/6 forward ECC -- 6 encoded bits for every 1 message bit. From the context, the ~1 kbps figure should mean the information rate; the tone rate would be 6x higher. 6.3. DOWNLINK SYSTEM PER
71.
by throwaway_yy2Di 12y ago
You can actually look up the exact number for the current Falcon (non-heavy). It's ~1,900 kg (I think), for the minimum C3 of 8.5 km^2/s^2. https://books.google.com/books?id=vpilMLP7OHQC&pg=PA112 http:/&
72.
by throwaway_yy2Di 12y ago
Anyone just see that piece of debris float away from the Dragon capsule? Is that normal? At about t+ 00:12:55 https://www.youtube.com/watch?v=p7x-SumbynI&t=1975
73.
by throwaway_yy2Di 12y ago
There's about a dozen extensions adding this feature -- it's an HN evergreen (because everyone loves it, and it's so easy to implement?): https://news.ycombinator.com/item?id=8706496 (I wrote one of the Firef
74.
by throwaway_yy2Di 12y ago
"Earth is about 4.5 billion years old, and early forms of life were definitely on the planet by 3.7 billion years ago. That bare fact seems to imply that it wasn’t hard to get life going on Earth; if initiating life was really improba
75.
by throwaway_yy2Di 12y ago
$1.26 - $3.77 per thousand characters... wow. I think it'd be cheaper to build your own acoustic modem and glue it to a handset.
76.
by throwaway_yy2Di 12y ago
There's no bounds testing in hget(): some valid sequences of operations will cause buffer overflows. For example, this should segfault: int (**table)[2] = hnew(); for (int j=0; j<40; ++j) { hset(table, (10 + j*SIZE)
77.
by throwaway_yy2Di 12y ago
See my other comment: log* only conquers the second level of Knuth arrows, e ↑↑ n. But you can easily generalize log* , in a way that mirrors the way Knuth arrows are constructed, and inverts them at any level. Say log*[1](n) = log(n)
78.
by throwaway_yy2Di 12y ago
log* doesn't beat Knuth arrows. See that log*(e ↑↑ n) = (n-1) log*(e) = n So log* is just the inverse of e ↑↑ n. That makes sense. Logarithm is the inverse of exponentiation. log* is iterated logartithm-ing,
79.
by throwaway_yy2Di 12y ago
That sounds like a fun weekend hack.
80.
by throwaway_yy2Di 12y ago
Even cooler: there's articles that claim the interiors of neutron stars are superconducting -- the current carried by proton pairs, rather than electron pairs. Maybe this is the source of magnetar dynamos. http://www.ohio.ed
81.
by throwaway_yy2Di 12y ago
Tangentially, the metallic hydrogen mentioned is one of the craziest chemical substances to possibly-exist [0]. Besides likely being a room-temperature superconductor (at ridiculous pressures, like 500 GPa), it's postulated to be metas
82.
by throwaway_yy2Di 12y ago
Note it's probably not useful to "stop and refuel" on any trajectory in space, since there's nothing slowing you down in a vacuum. Space flights are free ballistic trajectories: you don't consume any fuel on the way
83.
by throwaway_yy2Di 12y ago
"He pointed me at a Gliese astronomical dataset with 2223 of the closest stars. It's an older dataset, but it was perfect for what I needed." Are you the author? You may be interested in ESA's Hipparcos
84.
by throwaway_yy2Di 12y ago
(...either 2551 or 7563, depending on if you allow things like "7562 Kagiroino-Oka")
85.
by throwaway_yy2Di 12y ago
This is how you lose editing privileges.
86.
Human Exploration of Mars Design Reference Architecture 5.0 (2009) [pdf](nasa.gov)
6 points by throwaway_yy2Di 12y ago|0 comments
87.
by throwaway_yy2Di 12y ago
I love how every comment here links to a different implementation. I also made one (for Firefox/Greasemonkey), https://github.com/tom-szczarkowski/hn-stuff
88.
by throwaway_yy2Di 12y ago
These crosswords are NP-hard! D: Here's a short encoding of 3SAT: Alphabet: [01] Number of variables: N Columns: one for each clause, i.e.: r/.0...|..1..|....1/ (-x2 V x3 V x5) They're disjunctions of t
89.
by throwaway_yy2Di 12y ago
No, it's 64 decimal digits ~ 213 bits of precision! Octuple precision should have 8 * 32 = 256 bit word size. IEEE 754 single, double, and quadruple precision FP have 32, 64, and 128-bit word sizes, with significand precisions of 24, 5
90.
by throwaway_yy2Di 12y ago
I don't think it's a bandwidth problem. Here's a profile I captured in Firefox: https://i.imgur.com/RJkD3YC.png All of those image thumbnails were waiting on a single server response that took 9 seconds. This

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