Posted on 10/03/2019 8:17:05 AM PDT by BenLurkin
Albert Einstein received the Nobel Prize for explaining the photoelectric effect: in its most intuitive form, a single atom is irradiated with light. According to Einstein, light consists of particles (photons) that transfer only quantized energy to the electron of the atom. If the photon’s energy is sufficient, it knocks the electrons out of the atom. But what happens to the photon’s momentum in this process? Physicists at Goethe University are now able to answer this question. To do so, they developed and constructed and new spectrometer with previously unattainable resolution.
Doctoral student Alexander Hartung became a father twice during the construction of the apparatus. The device, which is three meters long and 2.5 meters high, contains approximately as many parts as an automobile. It sits in the experiment hall of the Physics building on Riedberg Campus, surrounded by an opaque, black tent inside which is an extremely high performing laser. Its photons collide with individual argon atoms in the apparatus, and thereby remove one electron from each of the atoms. The momentum of these electrons at the time of their appearance is measured with extreme precision in a long tube of the apparatus.
The device is a further development of the COLTRIMS principle that was invented in Frankfurt and has meanwhile spread across the world: it consists of ionizing individual atoms, or breaking up molecules, and then precisely determining the momentum of the particles. However, the transfer of the photon momentum to electrons predicted by theoretic calculations is so tiny that it was previously not possible to measure it. And this is why Hartung built the “super COLTRIMS.”
(Excerpt) Read more at scitechdaily.com ...
“...Doctoral student Alexander Hartung became a father twice during the construction of the apparatus...”
No wonder it took so long to construct...
Finally I can sleep at night again.
Grad school sux.
Hey, I thought that the momentum of a photon was already proven.
Children born while stuying for advanced degree. Been there done that. And working full time.
Fly line and tuft of yarn works outside.
Awesome
That is probably true, but they were conceived in the non study down times between those studies. Or at least one would presume that was the case. 8>)
otherwise it might get you banned from the library!
Anyone else come for the Jeff Epstein article??? Lol I’m going to go make some coffee.
And all Einstein needed was his own good brain.
I thought TBBT went off the air.
The “mystery”:
‘The question of which reaction partner (electron or atom nucleus) conserves the momentum of the photon has occupied physicists for over 30 years. “The simplest idea is this: as long as the electron is attached to the nucleus, the momentum is transferred to the heavier particle, i.e., the atom nucleus. As soon as it breaks free, the photon momentum is transferred to the electron,” explains Hartung’s supervisor, Professor Reinhard Dörner from the Institute for Nuclear Physics. This would be analogous to wind transferring its momentum to the sail of a boat. As long as the sail is firmly attached, the wind’s momentum propels the boat forward. The instant the ropes tear, however, the wind’s momentum is transferred to the sail alone.
‘However, the answer that Alexander Hartung discovered through his experiment is – as is typical for quantum mechanics – more surprising. The electron not only receives the expected momentum, but additionally one third of the photon momentum that actually should have gone to the atom nucleus. The sail of the boat therefore “knows” of the impending accident before the cords tear and steals a bit of the boat’s momentum. To explain the result more precisely, Hartung uses the concept of light as an electro-magnetic wave: “We know that the electrons tunnel through a small energy barrier. In doing so, they are pulled away from the nucleus by the strong electric field of the laser, while the magnetic field transfers this additional momentum to the electrons.”’
I was thinking home study. Never thought about the library. 8>)
When I was a grad student working on my master’s, I was in a group of 6 people. There were two older (ok this was over 40 years ago!) students doctoral though one might have been post-doc in the group. One of the older dudes was hippy-ish “60s-70s wild child” and so was his girlfriend. He got mad at the prof and told “the staff” he was going to f&*k his girlfriend Angie on the Doc’s desktop in the Doc’s office (he had a key for some reason!), the Doc’s desk in the lab, & on the lab bench where the Mossbauer was. I don’t think anything of it, but sure enough he comes in a few weeks latter with color Polaroids of him & Angie in various states of undress on Doc’s stuff, including the Mossbauer which had an active radiation source. I have to assume they actually did the deed. I still don’t see how this got back at the Doc. The world is full of weird people, always has been always will be!
Sounds more like an excuse to do it there. 8>)
I kept thinking as long as I don’t walk in on them.
I don’t care!
So I take it, that in no form, shape, or manner would it ever be construed as a pleasant surprise for the vast majority of people. 8>)
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