131–140 of 229 posts
Finding the thorium line is one of the most important open problems in precision/fundamental measurement.
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This actually has significant practical importance, because it is hoped that using this transition of the thorium nucleus it will be possible to build atomic clocks even better than those using transitions in the spectra of ions or neutral atoms, because the energy levels of the nucleus are less sensitive to any external influences. While in the best atomic clocks one must use single ions held in electromagnetic trap…
> clocks even better than those using transitions in the spectra of ions or neutral atoms I'd be interested to know how much more accurate a nuclear-state-transition clock might be than a conventional Caesium or Rubidium clock. TFA seems to make the point that a nuclear clock would be more resistant to external influences, such as EM radiation, than an atomic clock, and so could be used in experiments where such infl…
There are some real challenges in realization: this will take optical combs and all sorts of other stuff to really take advantage of.
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148nm is on the lower end of UV-C. It's higher-energy than the furthest ultraviolet light that the sun produces (200nm). If it were produced artificially, it'd be heavily absorbed by the atmosphere to the point of near opacity. If the visible spectrum was an octave, where the "tone" of a color wrapped around from red back to blue the way G wraps to A, it'd be the blue one octave above visible blue.
Nice to hear the octave relation used! "blue above visible blue" is a good name.. hmm, a little web tool to name these would be neat ;)
Else there's Octarine from the Discworld books, it's the colour of magic.
Another one in that same SO thread is err, quantifying synesthesia in the study of "chromophonics", where sound is assigned a color and vice-versa, that is, one could name a colour after a sound, which matches up with the earlier "octave" analogy.
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Classical there is used in the sense of “non relativistic”.
I thought relativistic quantum physics was not a thing (yet).
> It is consistent with both the principles of quantum mechanics and the theory of special relativity, and was the first theory to account fully for special relativity in the context of quantum mechanics.
What we don't have is a grand unified theory (a single set of rules that generates both theories), but we can consider relativistic effects in QM theories, and (I assume) vice versa.
> If the wavelength of the laser is chosen exactly right ... then maybe a special atomic nucleus could be manipulated with a laser, namely thorium-229. On November 21, 2023, the team was finally successful: the correct energy of the thorium transition was hit exactly, the thorium nuclei delivered a clear signal for the first time. So what's the wavelength? I felt like the article left me hanging. The answer is: 148.3…
148nm is on the lower end of UV-C. It's higher-energy than the furthest ultraviolet light that the sun produces (200nm). If it were produced artificially, it'd be heavily absorbed by the atmosphere to the point of near opacity. If the visible spectrum was an octave, where the "tone" of a color wrapped around from red back to blue the way G wraps to A, it'd be the blue one octave above visible blue.
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The article directly stated more precise atomic clocks.
Not a physicist, so I am asking out of curiosity and to learn: have the limitations to the precision of current atomic clocks posed any problems?
The latter is important in physics to determine if these constants are truly constant in space and time. Which is a large assumption we have about the universe.
We've known about photon-atom interactions for well over 100 years, with excitation of electrons which are either released or drop back to the original orbit, right?
So, ok, the Nucleus is smaller and the energies to alter the quantum state are probably higher, but - why is this so special, and why Thorium in particular rather than any old nuclei?
Disclaimer: I'm not a physicist.
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Lol that's a comic book name if I ever heard one. He's only one lab accident away from becoming a super hero/villain.
But then I'm only a name change and a lab accident away. And a name change isn't that hard...