It should be noted that this is a rare isotope of lutetium, which must be separated from the abundant isotope, so it is much more expensive than normal lutetium, which is already very expensive.
Nonetheless, the amount used in the clock is extremely small, so it does not influence much the cost, which is determined by a much more expensive set of lasers and optical components.
Lutetium 176 is very rare because chemical elements with an odd number of protons normally do not have isotopes with an even atomic mass, because those are unstable vs. beta decay.
Lutetium 176 is also radioactive, but its half-life time happens to be long enough so that a small amount of it has survived since the formation of the Solar System, like it also happened with the radioactive potassium 40 that is contained in the bodies of all living beings, which is another one of the 5 radioactive isotopes with even atomic mass of chemical elements with an odd atomic number (the others are vanadium 50, tantalum 180 and lanthanum 138).
2.6% natural abundance is more than enough to load an ion trap. Photoionization is so selective that one can load 46Ca from a sample with natural abundance (0.004%).
They wanted him to pay almost six years worth of his normal post-tax income. Did you have to pay six years worth of income? It took him a lot of work to get it down to 'only' 18.7k€.
After the 1944 D-Day landings, Allied planners thought that the war might easily stretch into 1946. The original plan was to drop dozens of atomic bombs on Germany. There was no such thing as "Let's sign a peace treaty where we stop fighting the Germans without invading Germany." You seem to be proposing that when we got to the German border in March 1945 we should have suddenly decided not to enter German territory, but only blockade them instead. The only reason we didn't drop dozens of bombs on both Germany and Japan was that our production lines didn't reach their three bombs per month full capacity until June.
So… while that’s true of most astronav systems to date (particularly the ones meant to be used during daytime, and especially with reference stars potentially near the horizon), I’m not sure that’s really a hard requirement.
If you restrict the domain to nighttime or exoatmospheric, a high-resolution wide-angle camera paired with an offline astrometry database has the makings of a strapdown astronav.
Widening the domain again, the natural motion of the vehicle is probably enough, when combined with inertial sensors to aid pixel-shift image stabilization, to achieve the same kind of processing gain as the older systems got with shutter-synchronous detection.
As a non-native speaker, you have to sound it out. It's a pun of "can't have your cake and eat it".
HN has been overrun with puns and attempts at humour in the past few years, while substantive comments have declined imho. But that's just the way it is.
Ha, OK. The darts seem designed to separate from the fletched part of the shaft, like a two-stage rocket, so the pun sounded confusingly truthful, as in they're not quite hafted.
Same thing with people who naively believe that amino acids can only be formed in space and can only be brought to Earth in asteroids, as opposed to forming *ON* Earth.
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