141–150 of 229 posts
No time to elaborate at the moment. Just want to say that this is extremely exciting news. Finding the thorium line is one of the most important open problems in precision/fundamental measurement.
That's what the Thorium said! [rim shot]
Laser induced fission anyone?
From the paper, the light is UV-C at around 140nm or 8.4 eV. But it has to be very precisely the right energy to cause the transition, since nuclear states don’t have any place to dump excess energy to.
> 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.
Earlier quoted context omitted.
148 doesn't feel too far removed from the visible spectrum, but it's in the wrong direction for animals to make use of it. I'm no biologist, but I'd be shocked if there were any animals that had adapted sensitivity to a type of radiation that they are never exposed to in nature. The sun doesn't really emit much UV-C light: https://en.wikipedia.org/wiki/Solar_irradiance#Absorption_an... and the light that is emitted i…
Also, even if there was some advantage to doing so, i'm not sure how animals could see a wavelength that short. They would need a photoreceptor protein which can absorb photons of that wavelength and turn them into some sort of chemical change which can trigger a signalling cascade. That protein would have to have a pair of molecular orbitals which are h * 148 nm apart. What can give you that? The ethene double bond…
> For the first time, it has been possible to use a laser to transfer an atomic nucleus into a state of higher energy and then precisely track its return to its original state. 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 ar…
This means that to exicte to this nuclear state is possible using an ultraviolet laser
It has important applications for nuclear theory, nuclear atomic clocks and fundemental constant metrology.
It's the curse of "probing" with massive energies. No one's a hundred percent certain of whether they're detecting something that's actually there - like there there - or whether they're looking at by-product of enormous collision energies.
Physicists are smart people! I could never do what they do. But there's a limit to certainty, and inside the proton especially there's unknown first principles at work. Bringing the precision of photons and lasers into this nucleon party is going to be huge. I can't wait!
Earlier quoted context omitted.
Yes, but a better clock means more precise measurements, means we can locate smaller masses to higher precision.
Does it? Inversion is rarely unique, and it's not due to the precision with which the field is measured. https://earthsciences.anu.edu.au/study/student-projects/nove... https://inside.mines.edu/~rsnieder/snieder_trampert_00.pdf Epilogue: Linear inverse problem theory is an extremely powerful tool for solving inverse problems. Much of the information that we currently have on the Earth’s interior is based on linear in…
That said, the gravity technique is one that actually gets used today. With better precision, it can be even more useful than it already is.