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Legible One

Egypt – Cairo – Ancient Memphis (UNESCO World Heritage List, 1979). Saqqara. Unas’ pyramid, Old Kingdom, Dynasty V. Interior, burial chamber. Ceiling decorated with stars and walls decorated with “Pyramid Texts”.

My less ambitious projects.  First a look at some “Pyramid Texts.”  The hieroglyphics above are from inside the pyramid of Unas ( also called Ounas or Wenis or Unis).  Later I hope to bring in some of Kurt Sethe’s handwritten transcriptions (from 1908) of texts from several 5th and 6th Dynasty pyramids (in

http://www3.lib.uchicago.edu/cgi-bin/eos/eos_title.pl?callnum=PJ1553.A1_1908)

 and maybe some spells from James Allen’s 2013 concordance of texts from Unis/Wenis (worth noting Unis’ texts are marked as ‘W’ in both Sethe’s and Allen’s concordances) through most of Teti, both Pepis and Pepi II’s three queens as found in:

http://ancientworldonline.blogspot.com/2013/07/a-new-concordance-of-pyramid-texts.html

Aethers and Pyramids?  What next?  Well, I started with a blog mulling over a book about kitchens during the Cold War and moved on to Russian Installation Art before setting out to reach the physics surrounding “mesons” of the 1935-1965 period from the beginning of the disappearance of the aether (around 1880).

On the way I found that, if you wander the internet looking for “aether”, you will find some very odd things such as the flat Earth and why it is motionless at the middle of the Universe.  So why not a little detour into Pyramid Texts, the sliding of the signifier, and Legible Space?  Again, wandering the internet shows there’s a lot of psychic things out there where anything related to pyramids is concerned.  However, as in the case of the aether, I will try to follow the way of a plumper, less centrally-located Earth while avoiding as much psychic activity and building of the unknown mental powers as possible.  I guess anything concerning the Quantum comes with much the same mental buzz verbiage, but that didn’t surprise me since I was used to a sustained low-level exposure to unlocking Quantum mind powers and had learned to adapt by shrinking my psychic aura to near zero – where it has stayed for the last few decades enabling me to encounter the aether and pyramids without any significant aural enlargements that I know of.

Some Pyramid Text sources:

James P. Allen’s The Ancient Egyptian Pyramid Texts 2nd ed Society of Biblical Literature 2015

Mark Lehner’s The Complete Pyramids  Thames and Hudson, 1997

John Romer’s A History of Ancient Egypt, Vol 2, St. Martin’s 2016

Originally the blog was going to center on mesons, events, bubble chambers, training scanners (that is women as scanners – they were thought to be better at spotting such things as small objects colliding in complex multi-dimensional ways ) to transcribe “events” into data.  The transcriptive machinery surrounding its operators was one of the things I wanted to consider.

So, I think the physics involved in reaching the problems surrounding mesons is going along well and now as we begin to look at the experimental world after 1923, we are almost to the first hints of the mesons.  

But I want to consider some other things as well.  I think I can collect them all under the heading of “legibility” and constructs such as “legible space.” Of course, the term “legible space” seems be commonly used to cover some ways of evaluating interior design – particularly where office spaces are concerned.  This abstract office space may have interesting resonances when we look into the legibility of tombs, inscriptions, and temples in relation to powers imagined to be at work in the cosmos, for example.  Or dreams in relation to the stories people want to believe about themselves, as another example.  Or artificial intelligence when it might need to evaluate its own overall strategies (as an extreme example). And then with all that – maybe a return via legibility to the aethers, bubble chambers and particle physics.

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Cosmic Rays 1922-1927

With Cosmic Rays we have some more back-tracking to do.  In some ways, Cosmic Rays are a tricker topic than I expected, though I maybe should have guessed that might be since (as Bruno Rossi points out early in his 1964 classic Cosmic Rays) not only was the exact nature of the “rays” not known, but not much was known about high energy interactions in general.  Moreover, since one thing I’m trying to do in this blog is to look at what people at the time thought was going on, all I can say is that what people thought was happening with Cosmic Rays in the period 1922 to 1927 was a long way from the whole story.  But anyway, let’s start with Millikan’s work since he was the person who decided to call whatever was happening “Cosmic Rays.”  Now, of course, ironically (as often happens with these things), at first, he was not convinced that the “rays” (actually just detectable ionization from an unknown source) were “cosmic” at all.

So…back to Millikan.  When Millikan started his work on the unknown source of ionization in 1922, he had finished measuring the photoelectric effect and was about to win the Nobel Prize for measuring the charge of the electron.  He produced small electroscopes and a device to record the ionization levels over time and sent those up in a set of balloons in March and April 1922 from Kelly Field in San Antonio, Texas.  Sure enough, the average “discharge rate” of the electroscopes at five kilometers above the Earth was three times what it was at the Earth’s surface.  Since that was only 25% of what earlier balloonists had found, Millikan naturally concluded that he was right and the rays came from somewhere else and not outer space ( as Qiaozhen Xu and Laurie M. Brown in M. j. Phys Jan 1987 point out on page 30 of their article on the history of Cosmic Ray studies).  But by 1925, Millikan was convinced that the powerful rays were coming from “above” – and could penetrate 22 meters of lake water.  Moreover, the rays were extremely powerful – fifty times (says Millikan based on absorption coefficients and the Compton effect) the most powerful gamma rays that had been measured up to that point or 30 MeV in our terms (or “32,000,000 volts” in Millikan’s terms).  That’s only, say, 15 times the energy of the gamma rays from the decay of Thorium — the “hard thorium C” line (2.65 times 106 e-volts)” – but that’s energies as known to L. H. Gray in 1930.  

Millikan was sure he was onto something big and the press went wild.  The “rays” (“Millikan Rays”) were described as “ultra-x-rays” a hundred times more penetrating than your basic x-rays (cited in the Qiaozhen Xu and Laurie M. Brown article).  Millikan managed the publicity well and got people to refer to the phenomena as “Cosmic Rays” and to attribute them to the formation of atomic nuclei all over the depths of space.  So that was a generally accepted picture of what was going on with Cosmic Rays up until 1927.  And here’s Millikan on the cover of Time for April 25, 1927 looking into a microscope or something for some reason:

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The Most Emergetic Photons Known (1931)

A small detour into radioactive photon sources before going into Cosmic Rays.  In 1929, the most energetic photons known (ie reliable sources with the highest measured energies) were the gamma rays from the decay of Thorium — the “hard thorium C” line (2.65 times 106 e-volts)” to quote L. H. Gray’s 1930 paper on what those gamma rays do when you scatter them from various elements as targets.  So that’s gamma rays at what we would call 2.65 MeV, though Schweber on page 82 of QED and the Men Who Made it, says 2.62 MeV which is presumably the modern (1990s) value of those photons.  Of course, these days we have seen and measured photons in Cosmic Rays with about 500 million times the energy of gamma rays from the hard thorium C” line.  Still, if you want to look at how electrons scatter photons, 2 or 3 MeV is a good place to notice how things are happening.

L. H. Gray, who was looking into what was going on with energetic gamma rays in 1929-1931, later went on to work on the effects of radiation on biological systems.  In his 1931 paper he summarized the earlier work on photon scattering (the Meitner is the Lise Meitner who was the first observer of nuclear fission a few years later):

 Tarrant, ‘ Proc. Roy. Soc.,’ A, vol. 128, p. 345 (1930);

 Meitner and Hupfeld, Natur wiss.,’ vol. 22, p. 534 (1930); and in ‘ Phys. Z.,’  vol. 31, p. 947,(1930)

Chao, ‘ Proc. Nat. Acad. Sci.,’ vol. 16, p. 431 (1930)

And his own earlier: (part i): ‘ Proc. Roy. Soc.,’ A, vol. 128, p. 361 (1930).

What everyone was noticing was that, at energies over about 2 MeV, the expected scattering was not quite happening as the Klein-Nishina equation based on Dirac’s work suggested that it would.  The energy was going somewhere – being absorbed and re-radiated or at least not going anywhere as the high energy photons that were expected.  Gray describes the disappearance of predicted scattering as an “increase in ionization,” ie generalized energy in the experimental space.  Which is to say, the energy is still there but not in the form of photons with their frequencies altered according to how they scattered.  Still, the Klein-Nishina formula worked very well for photon energies up to around 2 MeV.

As Pais points out in Inward Bound (pages 348-9), this correct functioning of the formula in relatively low energies happens partly because Klein and Nishina treated the radiation field semi-classically.  The purely quantum treatments of the radiation field in scattering situations done by Ivar Waller and Evgenievich Tamm in 1930 showed that electron momenta had to be summed over positive and negative values for the low energies in the purely classical Thomson Scattering range well below 2 MeV.

So, what was going on in even higher energies as we move into the 1930s?   

So again: next time: Cosmic Rays.

Compton looking for Cosmic Rays in the 1930s
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Approximations 1928

Here we carefully slide over three years of fundamental advances in microphysics.  From 1925 to 1928, basic Quantum Mechanics was worked out and Dirac wrote out his first version of how fields could be quantized.  By 1928, even Bohr was willing to believe that, as a general rule, energy is conserved, and even, as Pauli wrote to Bohr, willing to “let the stars shine in peace” – which was to say without requiring that energy not be conserved in order to shine, as Pais notes on page 312 of Inward Bound.  Pais’ book is my main source for the three years that this blog is more-or-less skipping.

But another last look back at the World of Bohr and the BKS proposal, mostly to puzzle over what was so puzzling about tracking exact trajectories (ie in the Compton effect, the relation between the angle of the deflection of the photon and its energy, not to mention the exact detection of events with Geiger counters) in the world of 1925.  It is even more puzzling in retrospect and confusing in most accounts of quantum physics because Bohr’s ideas about complementarity and the Copenhagen Interpretation are injected at the level of particle interactions where they tend to obscure the basic readability of many kinds of quantum events.

Moreover, you would think that Rutherford’s use of particle trajectories (in 1911, preliminary and necessary to Bohr’s work on quantum energy levels) to work out the basic structure of atoms around the nucleus could have hinted at how single events could be tracked usefully at the subatomic level.  I guess the basic problem was imagining the photon (light-quantum) as having a single definite interaction with a single definite electron.  Even now that view of possible events (eg. an X-ray photon hits a relatively free electron) is seen as only one among many possible events – though at certain energies that is a reasonable description or approximation of the event.  The crucial object to picture is the single photon carrying a specific momentum (and therefore a trajectory and a wavelength) and in some ways the popular picture of quanta still makes this difficult to imagine, perhaps due explanations that rely on emphasizing some of the stranger verbiage of the Copenhagen interpretation such as the notion of an observer rather than the results of an interaction – interactions which at certain energies are more-or-less legible in terms of what happens with detectors over time. 

So, 1928, what have we got specifically for photons hitting electrons?  As noted, things seem to have been shaping up for not violating the conservation of energy as a general solution to problems with describing quantum fields.  Compton received the Nobel Prize in 1927 for working out the nature of the Compton Effect in 1922 and (also in 1927), Dirac produced a paper (Dirac 1927b) introducing the idea of quantum electrodynamics (QED) in terms of the interaction of the electromagnetic field with things like atoms or electrons.  The paper deals primarily with the interactions of the light-quantum and notes that a light-quantum in the state of zero momentum (required to be a possible state by absorption and the conservation of energy, Bose-Einstein statistics and Born’s rule of probability) essentially cease to exist but then can also be potentially created out of the fields involved in emission.  So, there is already a kind of proto-Dirac Sea, though it is a sea of photons and not yet a sea of electrons as well.  For the situation in 1928, it is important to keep in mind that the entire Dirac picture of QED was not yet available.

In early 1928, Dirac brought out his paper on the electron (featuring the famous Dirac Equation, though not interpreted as it is now).  So, by early 1928, a QED description of the photon and electron were available.  Some of the events that happen when photons interact with relatively free electrons were understood.  At low (visible light) energies you had Thomson Scattering.  At X-ray energies you had the Compton Effect.   

So, what does happen over the whole range of photon energies when you scatter photons at various energies off of relatively free electrons?  If we focus as much as possible only on what was known about that in 1928, we begin to see a lot of odd pathways and answers to that question.  First, there is a useful approximation, the Klein-Nishina and second, there is a set of theoretical descriptions of relativistic photons and electrons (more-or-less the first versions of Dirac’s theory), and third, a source of powerful particles, electrons and/or photos – “Cosmic Rays” – that is beginning to be investigated.  Even now, in 2022, the term astrophysicists use for non-nuclear processes more energetic than Thomson Scattering is “the Klein-Nishina Regime” – which – from the point of view of 1928 – includes a domain of events of completely unknown natures.  So next time: Cosmic Rays.

Clash of Cosmic Views
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Statistical Points: Stories of the Compton Effect and BKS (Bohr-Kramers-Slater Proposal) in 1924-5

The stories of the Compton Effect and the BKS proposal remain somewhat convoluted in the mid-1920s.  For example, in both Peter Galison’s account in Image and Logic and Stuewer’s account in The Compton Effect, the experimental results of Compton and Simon using cloud chamber photographs are described as less convincing than coincidences using Geiger Counters.  In both cases, the events surrounding the recoil of electrons in relation to the energies of the X-rays were shown (ironically perhaps) to be statistically more likely to be explained by simple conservation of energy than by the BKS proposal of an overall statistical scheme where virtual fields mediated the interactions.  The possible irony is that the BKS proposal that interactions were in themselves mediated by layers of virtual statistical virtual events was shown statistically not to work for events where the time dependence of the interactions could be tracked.

            In Mehra’s account in The Historical Development of Quantum Theory, the Bothe-Geiger experiment results not only become known sooner in Europe in early 1925, but the in the comparison of predicted rates, the results based on BKS predictions are given, in terms of the Bothe-Geiger framework, more or less a zero chance of being detected in a time-dependent observation and confirmed, while the Compton-Debye interpretation in terms of an interaction that instantaneously conserves energy can be detected in a time-dependent situation and confirmed in one out of 10 interactions, ie more or less with an infinitely greater probability of detection and confirmation (ie one tenth is a considerable greater probability than 0).  The key moment in most stories comes when Geiger writes a letter to Bohr on April 17, 1925, but Max Born wrote Bohr in January three months earlier with the same news – which was that sometimes it looked like Einstein’s quanta could be seen as colliding with electrons while conserving energy the whole time, that is in a context where the time dependence could be noted, and in the Bothe-Geiger case the time dependent observations took the form of many chronometric yards of film strips or “moving paper charts.” By April 21, Bohr was willing to set the BKS proposal aside, at least as an explanation of the Compton Effect.  Mehra goes on to quote Pauli in a letter to Kramers in July 1925 where Pauli gives equal emphasis to the results of Compton and Simon’s experiment as to the Bothe-Geiger experiment.  The interweaving of the stories can be seen as even stranger than that since R. N. Sen has recently pointed out that    Von Neuman, in formulating his mathematical axioms of quantum mechanics (published in 1932) seems to have confused the particular time dependent measurements of the Bothe-Geiger experiment with the trajectories involved in the Compton-Simon experiment (see R.N. Sen, “Von Neuman’s Book, the Compton-Simon Experiment and the Collapse Hypothesis” in https://arxiv.org/pdf/2201.01299.pdf, from January 4, 2022).

Of course, the thing about the Compton Effect is that it shows that at certain energies (ie the energy of an X-ray photon interacting with a relatively free electron), the interaction can be seen as (or approximated as) a simple collision which in turn implies the photon can be seen as (or approximated as) a single quantum particle.  This clarified the representation of radiation but perhaps just as importantly, it suggested that tracing the precise energies, trajectories and charges of particles could be very informative about the forces involved once time was assumed to be on hand rather than part of a virtual scheme.  So one might isolate two different sets of explanatory practices moving on from the Compton Effect (and ignoring at this early point, as perhaps Von Neuman did by accident, the difference between the tracks as images and the tracks as time dependent events in detectors): one that pursues approximations over the whole range of energies for events of a certain type and one that seeks to derive information from tracing the precise energies, trajectories, and charges of particles.

Next post, we will look at some of the implications of approximating quantum interactions over a range of energies.

Meanwhile, here we have the early “Turing Complete” ENIAC controls without any Von Neuman: