by Theodore R Frimet
pass the uranium, please.
It was 10 marbles for 99 cents, plus shipping, and I couldn’t resist. Imagine, uranium embedded into glass. Not a new thing, of course! Uranium glass has been around before there was electric light. Imagine having a uranium glass vase, seated by the window, catching glancing photons from the setting sun. And glowing…green. Aside from radioactive glass being, well, very cool, and out-right geeky, I was becoming transfixed on some purposeful use of uranium marbles.
It started with an attempt to find a science book, on line, in MP3 format from our local library. And I was not disappointed. I found, Entanglement, by Amir D. Aczel and installed and downloaded Overdrive onto my iPhone as quickly as I could. Azcel thoroughly presents the topic and makes it a point, to repeat key concepts and re-weave them into the storyline. Although more of a history of science, there were many tidbits that got my juices going. And my mind seemed to wander off to new horizons.
The new horizon seemed to become entangled. I found old thoughts, become washed anew. Last year, during one of our AAAP Friday night observation, I shared a thought with an astronomer that the nebula that we were viewing, was gas a-glow from ultraviolet light emanations from the white dwarf, contained within. Reradiating light, it seems, was perfectly rational. Photons, being well, photons, would excite electrons in the nebula to higher energy states, only to settle down into a lower energy state, and re-emit a photon in the process. Hence the glowing. What I was unaware of, was that there is also a process called down-conversion. And now, being titillated with a new concept, I was apt to apply it..somehow..somewhere..
I gleefully put together an email to a scientist that knows how light propagates thru a medium, and started my suggestions on green glass, and somehow ended up asking if gravitational lensing, causing Einstein rings, entangles light. Re-reading the email, I must have bit my lip, because, at the least, I never suggested having two or more telescopes aiming at the phenomena to capture entangled photons. And of course, he may have been a physicist, however, he was no astronomer. So the thought may have been lost on him in its entirety. No matter, as the light coming forth from such distant objects inherently are highly incoherent. Having had their presumed entangled photons come into contact (measurement) with other cosmological hooligans, they became less fuzzy. They collapsed their wave functions long ago.
I learned, from the auditory text, that science has been able to entangle photons, and more complex items, such as 2,000 atoms of Rubidium. Hardly stellar stuff…not just yet. So I set myself up and got insightful when the author spoke of spontaneous parametric down-conversion (SPDC). As evidenced thru the application of laser experiments and non-linear crystals; two crystals were specified, one was lithium iodate, the other barium borate. And both exhibited a faint halo – with rainbow color. That meant that not all the laser light was emitted as expected. When measured, it became apparent that for every one photon in, we get two out, and more specifically, the frequency of the two output photons was one half the frequency of the input. Later analysis proved the light was a good source of quantum entanglement. The phenomenon, according to the author of my latest fling, was discovered in 1970 by DC Burnham & DL Weinberg. The Wikipedia listing gives credit to additional authors. The implementation of SPDC as a source of entangled photons, for experiments related to coherence, was done by the likes of Leonard Mandel (May 9, 1927 – February 9, 2001) and others (another Wiki reference).
So, I found my jumping off point. It was Astronomy Day at Jenny Jump, UACNJ, and we had 20 minutes or so to kill, while a member went about finding an adapter for the present speaker’s laptop. Two other club members, helped kill time on entanglement. And my idea of entanglement of photons from Einstein Rings, and White Dwarfs, got shot down really fast. So I played my Ace card, and suggested that the UV input into a uranium crystal, yields a frequency one half of that input. UV being about 778 Ghz, green light 545 (thanks Google), Perhaps we have two photons out, for every one, in? Nope, not exactly. The math simply does not work, here. However, this is my delusion, so we march on to say we have a new source of entanglement. Nothing new under the sun, I’m told, and because I am dealing with a macro system, and coherence isn’t likely. But I persist. I want to focus the green fuzzy uranium light thru a beam splitter. With one source hitting a cut-out triangle target, and the second source becoming the ghost. Expecting much from my marbles, I want to see quantum entanglement in action.
And then the brighter of the four of us, asks me a question. What exactly is entanglement? I started to tell him how a photon becomes entangled, but he interrupts me, and says, “no, what is the cause of entanglement”. I say, give me a few seconds to think on that. And then I remember seeing an article with a picture that shows some concentric circles. And I seem to recall that there were several points of circular intersection that were referred to as “entanglement”. I also recall, at this time, learning that many different wave forms, say multiple sin and cosine waves can contribute and add to one wave form. And that one wave can represent, something, say like an electron. So the “particle” aka electron, is as spread over many probabilities as is the many waves that can represent it. And I put together the two thoughts (either of which may have been highly inaccurate) and tell my friend: “When one wave function intersects with another, the point of intersection is the entanglement.”
So when my marbles arrive, I’ll count them out, and have some fun. I am assured as long as I don’t grind the glass down for ingestion, uranium glass is presumed safe. I did order a low cost UV light source, and some eye protection, as the UV is probably more damning than the uranium will ever be. I may not ever get a chance to focus really huge telescopes onto Einstein Rings, however, in a few days, I will be able to find my marbles.
Amateur Astronomers Association of Princeton 