164. Uncle Tungsten - XVI. Fusion & the End

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Uncle Tungsten

What has confused me about "protonation" -- the donation of protons to another atom or molecule -- is that the term suggests to me that protons leave a nucleus much like a wife breaking free of the strong force of a polygamous marriage. But the reality is quite different. A hydrogen proton (really the nucleus so, technically speaking a protium or at least a positive hydrogen ion or, let's say, a hydrogen cation) departs one (acid) family and moves on to another (base) family leaving its electron behind. I'm sorry, having introduced the polygamous marriage idea it's now hard not to see the proton as a heartless mother abandoning her small (probability distributed) child. (So it can't even be said where it is with any degree of certainty. And it's probably left behind in a negative hydroxide ion or anion.)


So now I have all this but I still have no idea why the proton leaves it's old family behind and is drawn to the base -- thus turning it's old family into an anion and its new family into a cation. With ionic and covalent bonds I get how valency is the motivation, if you will, that brings atoms together. There's something essential about acids and bases here that I'm missing.

This includes a very helpful animation showing a particular kind of protonation in action. From reading the text, it would seem that I'm not the only one having a hard time visualizing how this works. 

The cationic forms of hydrogen are called hydrons and there are three types: proton, deuteron (with a neutron), and triton (with two neutrons). If you de-ionize them by giving them an electron, they become hydrogen, deuterium, and tritium. Unless you have a plasma (like in the sun, as we shall see) naked hydrons are very rare but what you will find in acidic water is hydronium ions H3O+. Or if the water is alkali you will find more hydroxide anions OH-.

And I'm going to leave it at that and not even get into salts.

Chapter 24 - Brilliant Light - Continued

...
p305 It was not until 1929 that another idea was put forth: [about what powered the sun] the notion that, given the prodigious temperatures and pressures of a star’s interior, atoms of light elements might fuse together to form heavier atoms -- that atoms of hydrogen, as a start, could fuse to form helium; that the source of cosmic energy, in a word, was thermonuclear. Huge amounts of energy had to be pumped into light nuclei to make them fuse together, but once fusion was achieved, even more energy would be given out. This would in turn heat up and fuse other light nuclei, producing yet more.  

The use of “light” in “light nuclei” is a little confusing since we are talking about “light” in the other sense as well. Also, Nothing here supports or explains his contention that “more energy would be given out.” This is obviously the case, but the details of it remain a mystery to me. 

At temperatures and pressures like this [20 million degrees inside the sun]. atomic nuclei -- naked, stripped of their electrons -- would be rushing around at tremendous speed (the average energy of their thermal motion would be similar to that of alpha particles) and continually crashing, uncushioned, into one another, fusing to form the nuclei of heavier elements. 

In the sun, they would actually be forming alpha particles, since that’s what a helium nucleus is. 

...
Converting hydrogen to helium produced a vast amount of heat and light, for the mass of the helium atom was slightly less than that of four hydrogen atoms -- and this small difference in mass was totally transformed into energy, in accordance with Einstein’s famous e=mc2... 

I have to pause here. We will return to this chain of thought below.

This finally sent me to Wiki for more information. Wiki repeats what he says about the four hydrogen atoms but this makes absolutely no sense to me. Here’s the way I would describe it: 

Two free protons collide, with enough energy that they overcome the natural tendency of positively charged bodies to repulse each other, and stick together. Only the impact also shakes loose a positron and a neutrino. And this is where we have to get into the (seemingly intentionally) confusing world of Quantum Chromodynamics (QCD). 

A proton is not a fundamental particle but is currently understood to be composed of two up quarks and one down quark bound together by gluon fields. (The mass of the proton comes almost entirely from the gluon fields and the kinetic energy of the quarks.) 

A neutron is described the exact same way except that it has two down quarks and only one up quark. According to Wiki, “A free neutron is unstable, decaying to a proton, electron and antineutrino with a mean lifetime of just under 15 minutes... This radioactive decay, known as beta decay, is possible since the mass of the neutron is slightly greater than the proton. The free proton is stable.”

That positron I said was shaken loose is an anti-electron so when a proton becomes a neutron it gives off a positively charged particle and when a neutron decays into a proton it gives off a negatively charged particle. 

Now, finally, that neutrino I mentioned is a type of lepton (like the electron) but without charge.

So to summarize, two protons (each a little less massive than a neutron) collide, knock off a positron and a neutrino, and one of the protons turns into a more massive neutron. And the only difference between the new neutron and the old proton is the lack of charge (that positron, I guess) and a quark has shifted from up to down.

If anything is clear in all this it is that when nuclear physicists talk about “particles” they have a very special meaning in mind. As with electron energy states, it would probably be more understandable if they just dropped the particle language and used a more musical metaphor since this is all really about energy states and fields. Neutrinos even travel at c so they clearly have no mass.

That’s the first step. And may I say that I blame (without any justification) Murray Gell-Mann for all this jargon.

Next, the two nucleons (the technical term for protons and neutrons as a class of particles), now form a deuteron, held together by the strong nuclear force (in what can also be thought of as a deuterium nucleus (2H), except that there are no electrons to round out the atom) and collide with another free proton. This time the proton is trapped by the strong force creating a helium nucleus wanna-be with an atomic weight of 3 (3HE), and at the same time a gamma ray is released. (“Gamma ray” seems to be a catch-all term for high energy emissions.)

Now for the final step, two of these 3HE things crash together. Two of the protons fly off, but the remaining two protons and two neutrons stick together in the form of a beta particle or 4HE nucleus. 

From beginning to end, six -- not four -- protons entered the process, two continued on as free protons while two turned into neutrons and ended up stuck together by the strong force to the remaining two protons. Also, two positrons, two neutrinos, and two gamma rays were released. 

And, while he never mentions it, this fusion process in a star is known as Nucleosynthesis.

Sorry about this long digression. I will now resume the story about how the sun actually works,  


...To produce the energy generated in the sun, hundreds of millions of tons of hydrogen had to be converted to helium each second, but the sun is composed predominantly of hydrogen, and so vast is its mass that only a small fraction of it has been consumed in the earth’s lifetime. If the rate of fusion were to decline, then the sun would contract and heat up, restoring the rate of fusion; if the rate of fusion were to become too great, the sun would expand and cool down, slowing it. Thus, as [George] Gamow put it, the sun represented “the most ingenious, and perhaps only possible, type of ‘nuclear machine,’ “ a self-regulating furnace in which the explosive force of nuclear fusion was perfectly balanced by the force of gravitation. The fusion of hydrogen to helium not only provided a vast amount of energy, but also a new element in the world. And helium atoms, given enough heat, could be fused to make heavier elements, [carbon] and these elements, in turn, to make heavier elements still.

And I can’t help mentioning that the sun is the perfect place to put a fusion reactor. Trying to make one on earth is just silly. 


p306 Thus, by a thrilling convergence, two ancient problems were solved at the same time: the shining of stars, and the creation of the elements... Hydrogen, element 1, was not only the fuel of the universe, it was the ultimate building block of the universe, the primordial atom, as Prout had thought back in 1815. This seemed very elegant, very satisfying, that all one needed to start with was the first, the simplest of atoms. (Footnote: The universe started, Gamow conceived, as almost infinitely dense -- perhaps no larger than a fist. Gamow and his student Ralph Alpher went on to suggest (in a famous 1948 article that came to be known, after Hans Bethe was invited to add his name, as the alpha-beta-gamma paper), that this primal fist sized universe exploded, inaugurating space and time, and that in this explosion (which Hoyle, derisively, was to call the Big Bang) all of the elements were created.

But here he was wrong; it was only the lightest elements -- hydrogen and helium and perhaps a little lithium... 

I’m going to stop there because even that is not strictly speaking true. The result of the Big Bang was a plasma that took quite some time to cool down enough for even atomic hydrogen to form.

I would also like to point out that this is a reminder of -- if not exactly support for -- my argument against the existence of God as Creator. Things almost always start small and simple and grow in complexity. That everything would start with God is like suggesting that some super-transuranic element was the origin of chemistry. 


p307 Bohr’s atom seemed to me ineffable, transcendently beautiful -- electrons spinning, trillions of times a second, spinning forever in predestined orbits, a true perpetual-motion machine made possible by the irreducibility of the quantum, and the fact that the spinning electron expended no energy, did no work. And more complex atoms were more beautiful still, for they had dozens of electrons weaving separate paths, but organized, like tiny onions, in shells and subshells... [I’m not sure where he’s going with this, but I would rather imagine the electron shells as musical notes with more complex atoms generating chords. This reaches back to his original musical interpretation of the periodic table and forward to String theory.] Bohr’s atoms were surely close to Leibniz’s optimum world.

“God thinks in numbers,” Auntie Len used to say. “Numbers are the way the world is put together.” This thought had never left me, and now it seemed to embrace the whole physical world. I had started to read a little philosophy at this point, [uh-oh] and Leibniz, so far as I could understand him, appealed to me especially. He spoke of a “Divine mathematics,” with which one could create the richest possible reality by the most economical means, and this, it now seemed to me, was everywhere apparent: in the beautiful economy by which millions of compounds could be made from a few dozen elements, and the hundred-odd elements from hydrogen itself; the economy by which the whole range of atoms was composed from two or three particles; [prior to QCD] and in the way that their stability and identity was guaranteed by the quantal numbers of the atom itself -- all this was beautiful enough to be the work of God.

Chapter 25 - The End of the Affair

Like thousands of boys before him -- well, maybe a couple -- young Oliver finds he is growing out of his passion for chemistry and drifting towards other, and more social, interests. Here’s one of his reasons for this,  

...
p311 With the “new” quantum mechanics, developed in the mid-1920s, one could no longer see electrons as little particles in orbit, [sorry for jumping ahead last chapter] one had to see them now as waves; one could no longer speak of an electron’s position, only of its “wave function,” the probability of finding it in a particular place. [Nice alive and dead kitty.] One could not measure its position and velocity simultaneously. An electron, it seemed, could be (in some sense) everywhere and nowhere at once. All this set my mind reeling. I had looked to chemistry, to science, to provide order and certainty, and now suddenly this was gone. [This is an amazing recapitulation of Zen Physics!]  I found myself in a state of shock, and I was past my uncles now, and in deep water, alone. 

I can’t get over how perfect this is. What he doesn’t mention -- that was Darling’s focus -- is how quantum mechanics brought consciousness, the subjective, into the previously objective reality of science (the Socratic/Alexandrian perspective on reality). 

But Sacks wanted science to give him the truth about the world, certainty independent of what people wanted to believe. Instead it dumped him back in a place where cats were both alive and dead (and neither alive nor dead) until you peeked. What’s left then but philosophy and psychology? 


p312 This new quantum mechanics promised to explain all of chemistry. And though I felt an exuberance at this, I felt a certain threat, too. “Chemistry,” wrote Crookes, “will be established upon an entirely new basis. . . . We shall be set free from the need for experiment, knowing a priori what the result of each and every experiment must be.” I was not sure I like the sound of this. Did this mean that chemists of the future (if they existed) would never actually need to handle a chemical; might never see the colors of vanadium salts, never smell a hydrogen selenide, never admire the form of a crystal; might live in a colorless, scentless mathematical world? 


As with Richard Dawkins, he saved the good stuff for the end. I see the sense of this, of course, it's the only way you can appreciate the position the scientists were in as chemistry progressed step by step. But, like those people, you can't really understand the underlying reality of the chemistry until who get those last degrees of electronic and quantal understanding. Fortunately, I have to re-read it for blogging so I get the best of both worlds. 


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163. Uncle Tungsten - XVI. Quanta

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Uncle Tungsten

Chapter 24. Brilliant Light

p293 ...Fifty-odd elements were known by 1815; if Dalton was right, this meant fifty different sorts of atoms... William Prout, a chemically minded physician in London, observing that atomic weights were close to whole numbers and therefore multiples of the atomic weight of hydrogen, speculated that hydrogen was in fact the primordial element, and that all other elements had been built from it. Thus God needed to create only one sort of atom, and all the others, by a natural “condensation,” could be generated from this. 

William Prout (1785-1850) - This was known as Prout's hypothesis. Someone at the turn of the century, learning about radioactive cascades, might imagine the reverse -- that it all started with some super heavy element that broke down into the known elements. 

p294 [Harry Moseley, in 1913, uses X-ray spectroscopy to, as Soddy said,] “call the roll” of the elements. No gaps could be allowed in the sequence, only even, regular steps. If there was a gap, it meant that an element was missing. One now knew for certain the order of the elements, and that there were ninety-two elements and ninety-two only, from hydrogen to uranium. And it was now clear that there were seven missing elements, and seven only, still to be found. The “anomalies” that went with atomic weights were resolved: tellurium might have a slightly higher atomic weight than iodine, but it was element number 52, and iodine was 53. It was atomic number, not atomic weight, that was crucial.

p295 The brilliance and swiftness of Moseley’s work, which was all done in a few months of 1913-14, produced mixed reactions among chemists. Who was this young whippersnapper, some older chemists felt, who presumed to complete the periodic table... But Urbain, one of the greatest analytic chemists of all... at once appreciated the magnitude of the achievement... Moseley had in fact confirmed the periodic table and reestablished its centrality. “The law of Moseley . . . confirmed in a few days the conclusions of my twenty years of patient work.”

...The atomic number indicated the nuclear charge, indicated the element’s identity, its chemical identity, in an absolute and certain way. There were, for example, several forms of lead -- isotopes -- with different atomic weights, but all of these had the same atomic number, 82...
...
Rutherford and Moseley had chiefly been concerned with the nucleus of the atom, its mass and units of electrical charge. But it was the orbiting electrons, presumably, their organization, their bonding, that determined an element’s chemical properties, and (it seemed likely) many of its physical properties, too. And here, with the electrons, Rutherford’s model of the atom came to grief. According to classical, Maxwellian physics, such a solar-system atom could not work, for the electrons whirling about the nucleus more than a trillion times a second should created radiation in the form of visible light, then collapse inward as its electrons, their energy lost, crashed into the nucleus. But the actuality (barring radioactivity) was that elements and their atoms lasted for billions of years, lasted in effect forever. How then could an atom possibly be stable...
...
p297 It was Niels Bohr, also working in Rutherford’s lab in 1913, who bridged the impossible, by bringing together Rutherford’s atomic model with [Max] Planck’s quantum theory. The notion that energy was absorbed or emitted not continuously but in discrete packets, “quanta,” had lain silently, like a time bomb, since Planck had suggested it in 1900. Einstein had made use of the idea in relation to photoelectric effects, but otherwise quantum theory and its revolutionary potential had been strangely neglected, until Bohr seized on it to bypass the impossibilities of the Rutherford atom... Bohr postulated... an atom that had a limited number of discrete orbits, each with a specific energy level or quantal state. The least energetic of these, the closest to the nucleus, Bohr called the “ground state” -- an electron could stay here orbiting the nucleus, without emitting or losing any energy, forever. This was a postulate of startling, outrageous audacity, implying as it did that the classical theory of electromagnetism might be inapplicable in the minute realm of the atom.

There was, at the time, no evidence for this; it was a pure leap of inspiration, imagination -- not unlike the leaps he now posited for the electrons themselves, as they jumped, without warning or intermediates, from one energy level to another. For in addition to the electron’s ground state, Bohr postulated, there were higher-energy orbits, higher-energy “stationary states,” to which electrons might be briefly translocated. Thus if energy of the right frequency was absorbed by an atom, an electron could move from its ground state into a higher-energy orbit, though sooner or later it would drop back to its original ground state, emitting energy of exactly the same frequency as it had absorbed -- this is what happened in fluorescence or phosphorescence, and it explained the identity of spectral emission and absorption lines, which had been a mystery for more than fifty years. 

Atoms, in Bohr’s vision, could not absorb or emit energy except by these quantum jumps -- and the discrete lines of their spectrum were simply the expression of the transitions between their stationary states. The increments between energy levels decreased with distance from the nucleus, and these intervals, Bohr calculated, corresponded exactly to the lines in the spectrum of hydrogen (and to Balmer’s formula for these)... Einstein felt that Bohr’s work was “an enormous achievement,” and, looking back thirty-five years later, he wrote, “{it} appears to me as a miracle even today. . . . This is the highest form of musicality in the sphere of thought.” The spectrum of hydrogen -- spectra in general -- had been as beautiful and meaningless as the markings on butterflies’ wings, Bohr remarked; but now one could see that they reflected the energy states within the atom, the quantal orbits in which the electrons spun and sang. “The language of spectra,” wrote the great spectroscopist Arnold Sommerfeld, “had been revealed as an atomic music of the spheres.”

It really is impossible to not think of this in musical terms. Especially the jumping from one state to another like jumping from one note to another -- up in pitch and then back down again. This must have been such a wonderful time to be a chemist as the curtain was being drawn back revealing the actual workings of chemistry. Also, I just got why plants only really respond to certain colors (frequencies) of light.

There is a break in the science here as the world is gripped by the Great War. Moseley dies after being shot in the head at Gallipoli. After the war Bohr goes on to make sense of the order of electrons in larger atoms. 


p299 ...he now extended his notion to a hierarchy of orbits or shells for all the elements. These shells, he proposed, had definite and discrete energy levels of their own... Bohr’s shells corresponded to Mendeleev’s periods, so that the first, innermost shell, like Mendeleev’s first period, accommodated two elements, and two only. [H, He] Once this shell was completed, with its two electrons, a second shell began, and this, like Mendeleev’s second period, could accommodate eight electrons and no more. [Li, Be, B, C, N, O, F, Ne] Similarly for the third period or shell...

So to continue the musical analogy, atoms are like musical instruments that can play only a certain range of notes. 


p300 Thus the position of each element in the periodic table represented the number of electrons in its atoms, and each element’s reactivity and bonding could now be seen in electronic terms, in accordance with the filling of the outermost shell of electrons, the so-called valency electrons. [Finally!] The inert gases each had completed outer valency shells with a full complement of eight electrons, and this made them virtually unreactive. [Don’t we need to know the shell order here? (See the video at the end for that info.)] The alkali metals, in Group I, had only one electron in their outermost shell, and were intensely avid to get rid of this, to attain the stability of an inert-gas configuration; the halogens in Group VII, conversely, with seven electrons in their valency shell, were avid to acquire an extra electron and also achieve an inert-gas configuration. [That seems an odd way of putting it, but I know what he means. I made the mistake of consulting Wiki to see if I could find a way to put it better and discovered (surprise!) it's far more complicated than I imagined. You can click HERE if you want to see what I mean. ] Thus when sodium came into contact with chlorine, there would be an immediate (indeed explosive) union, each sodium atom donating its extra electron, and each chlorine atom happily receiving it, both becoming ionized in the process. 

This threw me but I finally worked it out: While sodium and chlorine are independently restless because of their relative valency conditions, as soon as they share that electron -- while the salt they form is electrically neutral -- each atom becomes charged since one is now short an electron and becomes positively charged (a cation) as the other gains an electron and becomes negatively charged (an anion). Thus they are electromagnetically bound together by their valency needs. 

Also, when he says above that they become "ionized," in the way I've just described, this is also to say that this is an ionic bond -- as opposed to a covalent bond. I don't think Sacks ever gets around to talking about the covalent bond.  


The placement of the transition elements and the rare-earth elements in the periodic table had always given rise to special problems. Bohr now suggested an elegant and ingenious solution to this: the transition elements, he proposed, contained an additional shell of ten electrons each; the rare-earth elements an additional shell of fourteen. These inner shells, deeply buried in the case of the rare-earth elements, did not affect chemical character in nearly so extreme a way as the outer shells; hence the relative similarity of all the transition elements and the extreme similarity of all the rare-earth elements. 

Not a clue  

Bohr’s electronic periodic table, based on atomic structure, was essentially the same as Mendeleev’s empirical one based on chemical reactivity... Whether one inferred the periodic table from the chemical properties of the elements or from the electronic shells of their atoms, one arrived at exactly the same point. (Footnote: ...Moseley had observed that element 72 was missing, but could not say whether it would be a rare-earth element or not... Bohr, with his clear idea of the number of electrons in each shell, was able to predict that element 72 would not be a rare-earth element, but a heavier analog of zirconium. He suggested that his colleagues in Denmark seek this new element in zirconium ores, and it was swiftly found (and named hafnium, after the old name for Copenhagen). This was the first time the existence and properties of an element were predicted not by chemical analogy, but on the purely theoretical basis of its electronic structure.) Moseley and Bohr had made it absolutely clear that the periodic table was based on a fundamental numeric series that determined the number of elements in each period: two in the first period, eight each in the second and third, eighteen each in the fourth and fifth; thirty-two in the sixth and perhaps also the seventh. I repeated this series -- 2, 8, 8, 18, 18, 32 -- over and over to myself.

Another way of looking at this is to add this series together giving you 2, 10, 18, 36, 54, 86. Which are simply the atomic numbers of Group VII, which Sacks insists on calling "inert" gases though "noble" gases seems to be the preferred usage today. 


...
p302 ...The character and identity of the elements... could now be inferred from their atomic numbers, which no longer just indicated nuclear charge but stood for the very architecture of each atom. It was all divinely beautiful, logical, simple, economical, God’s abacus at work.

What made metals metallic? ... The conductivity of metals was ascribed to a “gas” of free and mobile electrons, easily detached from their parent atoms -- this explained why an electric field could draw a current of mobile electrons through a wire. Such an ocean of free electrons, on the surface of a metal, could also explain its special luster, for oscillating violently with the impact of light, these would scatter or reflect any light back on its own path. 

See also Metallic bonding. 

The electron-gas theory carried the further implication that under extreme conditions of temperature and pressure, all the nonmetallic elements, all matter, could be brought into a metallic state. This had already been achieved with phosphorus in the 1920s, and it was predicted, in the 1930s, that at pressures in excess of a million atmospheres it might be achieved with hydrogen, too -- there might be metallic hydrogen, it was speculated, at the heart of gas giants like Jupiter. The idea that everything could be “metallized” I found deeply satisfying. (Footnote: It was also wondered, early in the twentieth century, what might happen to the “electron gas” in metals if they were cooled to temperatures near absolute zero -- would this “freeze” all the electrons, turning the metal into a complete insulator? What was found, using mercury, was the complete opposite: the mercury became a perfect conductor, a superconductor, suddenly losing all its resistance at 4.2 degrees above absolute zero. Thus one could have a ring of mercury... with an electrical current flowing around it with no diminution, for days, forever.)

p303 ...How could a huge amount of red light be less effective [with fluorescence, phosphorescence, photoelectric cells] than a tiny amount of blue light? It was only after I had learned something of Bohr and Planck that I realized the answer... must lie in the quantal nature of radiation and light, and the quantal states of the atom. Light or radiation came in minimum units or quanta, the energy of which depended on their frequency. A quantum of short-wavelength light -- a blue quantum, so to speak -- had more energy than a red one, and a quantum of X-rays or gamma rays had for more energy still. Each type of atom or molecule -- whether of a silver salt in a photographic emulsion, or of hydrogen or chlorine in the lab, or of cesium or selenium in Uncle Abe’s photocells, or of calcium sufide or tungstate in Uncle Dave’s mineral cabinet -- required a certain specific level of energy to elicit a response; and this might be achieved by even a single high-energy quantum, where it could not be evoked by a thousand low-energy ones.

p304 ...It was only when Uncle Abe showed me his spinthariscope and I saw the individual sparkles in this that I started to realize that light, all light, came from atoms or molecules which had first been excited and then, returning to their ground state, relinquished their excess energy as [a quanta] of visible radiation.  With a heated solid, such as a white-hot filament, energies of many wavelengths were emitted; with an incandescent vapor, such as sodium in a sodium flame, only certain very specific wavelengths were emitted. (The blue light in a candle flame which had so fascinated me as a boy, I later learned, was generated by cooling dicarbon molecules as they emitted the energy they had absorbed when heated.) 

This would appear to be incorrect. Dicarbon only exists at a temperature far hotter than that found in a candle flame. The blue is where the hydrocarbon molecules of the wax are being broken apart into hydrogen and carbon.

Also, what he says above about the spinthariscope is a bit confusing since those "scintillations" are not instances of quantal radiation. Alpha and beta decay are not chemical but radioactive processes. I guess he means that seeing the scintillations made him reflect on the very different process that generated chemical illumination, but this is not particularly clear. 

Sacks can't tell every science story of this amazing period, but there's one that he skips that I need to say something about. Or rather, I'm going to let Wiki tell it: 

At the end of the 1920s Bohr, Heisenberg and Pauli had worked out the Copenhagen interpretation of quantum mechanics, but it was rejected by Planck, and by Schrödinger, Laue, and Einstein as well. Planck expected that wave mechanics would soon render quantum theory—his own child—unnecessary. This was not to be the case, however. Further work only cemented quantum theory, even against his and Einstein's philosophical revulsions. Planck experienced the truth of his own earlier observation from his struggle with the older views in his younger years: "A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it."^[21] 

What a magnificent scientific debate it was when you consider that Planck, Schrodinger and Einstein were all on the losing side. You can also (almost) see this as a variation of Jonathan Haidt's "elephant." Scientists so buy into their own theories that -- even when these theories break an old paradigm -- the same scientists fight just as doggedly when the next paradigm shift comes along. 


I'm going to take a break here and wrap this, and the book up next time.

HERE'S something I ran into on YouTube (after writing this post) while trying (still without success) to get a better understanding of protonation -- which may yet be the death of me. What I find particularly interesting about this is -- to play my game of transporting people from the past to show them YouTube videos -- if you showed this video to Boyle, Lavoisier, Davy, Faraday, and all the other great figures of chemistry and science we have met here, including especially Mendeleev, they would be astonished and confused and some would probably be hard to convince. None of the "Great Figures" of chemistry (who died much before WW2) had any clue about how chemistry actually worked. Of why the elements behaved as they did. After alchemy was left behind it still took over a century before science could really make sense out of what was happening. And then -- the ultimate joke -- the underlying reality turned out to be as mystical and strange as anything the alchemists could make up. 

We now have "atoms" which can be viewed either as tiny machines or (in the case of hydrogen) a tone or (in the case of the other atoms) a chord that, if left alone, will "work" or "sound" for -- I think the latest estimate is -- quadrillions of years. And as we will see next time, the nucleus of atoms (which Hank Green in that video -- I think mistakenly -- said could be thought of as actual "particles") are, if anything stranger than electrons. The language of QCD would make the craziest alchemist blush.


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162. Uncle Tungsten - XV. Transmutation at last

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Uncle Tungsten

Chapter 22 - Cannery Row

This chapter is about biology, especially marine biology, and music and puberty. Very little here demands inclusion in this blog, but I do want to give you this quote about music as it’s a very concise statement of what’s been said before about the primacy of music. 


p276 ...the beauty, the love of science, no longer entirely satisfied me, and I hungered now for the human, the personal.

It was music especially which brought this hunger out, and assuaged it; music which made me tremble, or want to weep, or howl; music which seemed to penetrate me to the core, to call to my condition -- even though I could not say what it was “about,” why it affected me the way it did. Mozart, above all, raised feelings of an almost unbearable intensity, but to define these feelings was beyond me, perhaps beyond the power of language itself.


Chapter 23 - The World Set Free

[In which we return to the Curies,] p281 The Curies had noticed from the start that their radioactive substances showed a strange power to “induce” radioactivity all around them. They found this both intriguing and irritating, for the contamination of their equipment made it nearly impossible to measure the radioactivity of the samples themselves.

The different objects in the chemical laboratory {Marie wrote in her thesis} . . . soon acquired radioactivity. Dust particles, the air of the room, clothing, all became radioactive. The air of the room became a conductor. In our laboratory the evil has become acute, and we no longer have any apparatus properly insulated.  

(Footnote: Marie Curie’s own laboratory notebooks, a century later, are still considered too dangerous to handle and are kept in lead-lined boxes.)
...
p182 ... They had found, as early as 1897, that if thorium was kept in a tightly shut bottle its radioactivity increased, returning to its previous level as soon as the bottle was opened. But they did not follow up on this observation, and it was Ernest Rutherford who first realized the extraordinary implications of this: that a new substance was coming into being, being generated by the thorium; a far more radioactive substance than its parent.

Rutherford enlisted the help of the young chemist Frederick Soddy, and they were able to show the “emanation” of thorium was in fact a material substance, a gas, which could be isolated. It could be liquified, almost as easily as chlorine, but it did not react with any chemical reagent; it was in fact just as inert as argon and the other newly discovered inert gases. At this point Soddy thought that the “emanation” of thorium might be argon, and he was (as he wrote later)

overwelmed with something greater than joy -- I cannot very well express it -- a kind of exaltation. . . . I remember quite well standing there transfixed as though stunned by the colossal impact of the thing and blurting out -- or so it seemed at the time, “Rutherford, this is transmutation: the thorium is disintegrating and transmuting itself into argon gas.”

Rutherford’s reply was typically aware of more practical implications: “For Mike’s sake, Soddy, don’t call it transmutation. They’ll have our heads off as alchemists.” 

But the new gas was not argon; it was a brand new element with its own unique bright-line spectrum. It diffused very slowly and was exceedingly dense -- 111 times as dense as hydrogen, whereas argon was only 20 times as dense. Assuming a molecule of the new gas was monatomic, containing only one atom like the other inert gases, its atomic weight would be 222. Thus it was the heaviest and last in the inert gas series, and as such could take its place in the periodic table, as the final member of Mendeleev’s Group 0. Rutherford and Soddy provisionally named it thoron or Emanation. [Soon to be known as radon.]

p283 Thoron disappeared with great speed -- half of it was gone in a minute, three-quarters in two minutes, and in ten minutes it was no longer detectable. It was the rapidity of this breakdown (and the appearance of a radioactive deposit in its place) which allowed Rutherford and Soddy to perceive what had not been clear with uranium or radium -- that there was indeed a continuous disintegration of the atoms of radioactive elements, and with this their transformation to other atoms.

Each radioactive element, they found, had its own characteristic rate of breakdown, its own “half-life.” The half-life of an element could be given with extraordinary precision, so that the half-life of one radon isotope, for instance, could be calculated as 3.8235 days. But the life of an individual atom could not be predicted in the least. I became more and more bewildered by this thought, and kept rereading Soddy’s account:

The chance at any instant whether an atom disintegrates or not in any particular second is fixed. It was nothing to do with any external or internal consideration we know of, and in particular is not increased by the fact that the atom has already survived any period of past times. . . . All that can be said is that the immediate cause of atomic disintegration appears to be due to chance.  

Here I’m imagining the stray cat, soon to become known as Schrodinger's Cat, getting restless in its carrier. 


The life span of an individual atom, apparently, might vary from zero to infinity, and there was nothing to distinguish an atom “ready” to disintegrate from one that still had a billion years before it.

I found this profoundly mystifying and disconcerting, [and worse was to come] that an atom might disintegrate at any time, without any “reason” to do so. It seemed to remove radioactivity from the realm of continuity or process, from the intelligible, causal universe -- and to hint at a realm where laws of the classical sort meant nothing whatsoever. 

p284 The half-life of radium was much longer than that of its emanation, radon -- about 1,600 years. But this was still very small compared to the age of the earth -- why, then, if it steadily decayed, had all the earth’s radium not disappeared long ago? The answer, Rutherford inferred, and was soon able to demonstrate, was that radium itself was produced by elements with a much longer half-life, a whole train of substances that he could trace back to the parent element, uranium. Uranium in turn had a half-life of four and a half billion years, roughly the age of the earth itself. Other cascades of radioactive elements were derived from thorium, which had an even longer half-life than uranium. Thus the earth was still living, in terms of atomic energy, on the uranium and thorium that had been present when the earth formed. 

An interesting aside here, I recently learned that in much earlier days, when there was a great deal more uranium that hadn't worked its way down the cascade, clumps of the stuff had gone spontaneously critical setting off uncontrollable chain reactions inside the earth. See HERE.

These discoveries had a crucial impact on a long-standing debate about the age of the earth. The great physicist Kelvin, writing in the early 1860s, soon after the publication of The Origin of Species, had argued that, based on its rate of cooling, and assuming no source of heat other than the sun, the earth could be no more than twenty million years old, and that in another five million years it would become too cold to support life. This calculation was not only dismaying in itself, but was impossible to reconcile with the fossil record, which indicated that life had been present for hundreds of millions of years... Darwin was greatly disturbed by this.

It was only with the discovery of radioactivity that the conundrum was solved. The young Rutherford, it was said, nervously facing the famous Lord Kelvin, now eighty years old, suggested that Kelvin’s calculation had been based on a false assumption. There was another source of warmth besides the sun... Rutherford held up a piece of pitchblende, the age of which he had estimated from the amount of helium it contained. This piece of the earth, he said, was at least 500 million years old.

p285 Rutherford and Soddy were ultimately able to delineate three separate radioactive cascades, each containing a dozen or so breakdown products emanating from the disintegration of the original parent elements... There was no room in the periodic table for three dozen elements between bismuth and thorium... Only gradually did it become clear that many of the elements were just versions of one another; the emanations of radium and thorium and actinium, for example, though they had widely differing half-lives, were chemically identical, all the same element, though with slightly different atomic weights. (Soddy later named these isotopes.) And the end points of each series were similar -- radium G, Actinium E, and thorium E, so-called, were all isotopes of lead.

Every substance in these cascades of radioactivity had its own unique radio signature, a half-life of fixed and invariable duration, as well as a characteristic radiation emission, and it was this which allowed Rutherford and Soddy to sort them all out, and in so doing to found the new science of radiochemistry.
...
p286 I loved chemistry in part because it was a science of transformation, of innumerable compounds based on a few dozen elements, themselves fixed and invariant and eternal. The feeling of the element’s stability and invariance was crucial to me psychologically, for I felt them as fixed points, as anchors, in an unstable world. But now, with radioactivity, came transformations of the most incredible sort. What chemist would have conceived that out of uranium, a hard, tungsteny metal, there could come an alkaline earth metal like radium; an inert gas like radon; a tellurium-like element, polonium; radioactive forms of bismuth and thallium; and finally, lead -- exemplars of almost every group in the periodic table?

No chemist would have conceived this (though an alchemist might), because the transformations lay beyond the sphere of chemistry. No chemical process, no chemical attack, could ever alter the identity of an element, and this applied to the radioactive elements too. Radium, chemically, behaved similarly to barium; its radioactivity was a different property altogether, wholly unrelated to its chemical or physical properties. Radioactivity was a marvelous (or terrible) addition to these, a wholly other property (and one that annoyed me at times, for I loved the tungstenlike density of metallic uranium, and the fluorescence and beauty of its minerals and salts, but I felt I could not handle them safely for long; similarly I was infuriated by the intense radioactivity of radon, which otherwise would have made an ideal heavy gas).

Radioactivity did not alter the realities of chemistry, or the notion of elements; it did not shake the idea of their stability and identity. What it did do was hint at two realms in the atom -- a relatively superficial and accessible realm governing chemical reactivity and combination, and a deeper realm, inaccessible to all the usual chemical and physical agents and their relatively small energies, where any change produced a fundamental alteration of the element’s identity. 

p287 Uncle Abe had in his house a “spinthariscope,” just like the ones advertised on the cover of Marie Curie’s thesis. [These were ads, like the ones I mentioned on my copy of The Private Papers of Henry Ryecroft.] It was a beautifully simple instrument, consisting of a fluorescent screen and a magnifying eyepiece, and inside, an infinitesimal speck of radium. Looking through the eyepiece, one could see dozens of scintillations a second -- when Uncle Abe handed me this, and I held it up to my eye, I found the spectacle enchanting, magical, like looking at an endless display of meteors or shooting stars.

 Spinthariscopes, at a few shillings each, were fashionable scientific toys in Edwardian drawing rooms -- a new and uniquely twentieth-century accession, next to the stereoscopes and Geissler tubes inherited from Victorian times. But if they made their appearance as a sort of toy, it was rapidly appreciated that they also showed one something fundamentally important, for the tiny sparks or scintillations one saw came from the disintegration of individual atoms of radium, from the individual alpha particles each shot off as it exploded. No one would have imagined, Uncle Abe said, that we would ever be able to see the effects of individual atoms, much less to count them individually.

“Here there is less than a millionth of a milligram of radium, and yet, on the small area of the screen, there are dozens of scintillations a second. Imagine how many there would be if we had a gram of radium -- a thousand million times this amount.”

“A hundred thousand million,” I calculated.

“Close,” Uncle said. “One hundred and thirty-six thousand million, to be exact -- the number never varies. Every second, one hundred and thirty-six thousand million atoms in a gram of radium disintegrate, shoot off their alpha particles -- and if you think of this going on for thousands of years, you’ll get some idea of how many atoms there are in a single gram of radium.”

Experiments around the turn of the century had shown that not only alpha rays but several other sorts of ray were being emitted by radium. Most of the phenomena of radioactivity could be attributed to these different sorts of rays: the ability to ionize air was especially the prerogative of the alpha rays, while the ability to elicit fluorescence or affect photographic plates was more marked with the beta rays. Every radioactive element had its own characteristic emissions: thus radium preparations emitted both alpha and beta rays, where polonium preparations emitted only alpha rays. Uranium affected a photographic plate more quickly than thorium, but thorium was more potent in discharging an electroscope.

p288 The alpha particles emitted by radioactive decay (they were later shown to be helium nuclei) were positively charged and relatively massive -- thousands of times more massive than beta particles or electrons [or positrons] -- and they traveled in undeviating straight lines, passing straight through matter, ignoring it, without any scattering or deflection (although they might lose some of their velocity in so doing). This, at least, appeared to be the case, though in 1906 Rutherford observed that there might be, very occasionally, small deflections. Others ignored this, but to Rutherford these observations were fraught with possible significance. Would not alpha particles be ideal projectiles, projectiles of atomic proportions, with which to bombard other atoms and sound their structure? [Boy’s will be boys. No sooner do we discover something than we try to find a way to shoot it at things. Another sort of “cascade” leading to the Large Hadron Collider at Cern.] [Hans Geiger and Ernest Marsden conduct an experiment to test what happens when you shoot alpha particles at a very thin gold foil,] ...they found that roughly one in eight thousand particles showed a massive deflection -- of more than 90 degrees, and sometimes even 180 degrees. Rutherford was later to say, “It was quite the most incredible event that ever happened to me in my life. It was almost as incredible as if you fired a fifteen-inch shell at a piece of tissue paper and it came back and hit you.”

Rutherford pondered these curious results for almost a year, and then, one day, as Geiger recorded, he “came into my room, obviously in the best of moods, and told me that now he knew what the atom looked like and what the strange scatterings signified.”

p289 Atoms, Rutherford had realized, could not be a homogeneous jelly of positivity stuck with electrons like raisins (as J.J. Thomson had suggested, in his “plum pudding” model of the atom), for then the alpha particles would always go through them. Given the great energy and charge of these alpha particles, one had to assume that they had been deflected, on occasion, by something even more positively charged than themselves. Yet this happened only once in eight thousand times. The other 7,999 particles might whiz through, undeflected, as if most of the gold atoms consisted of empty space; but the eight-thousandth was stopped, flung back in its tracks, like a tennis ball hitting a globe of solid tungsten. The mass of the gold atom, Rutherford inferred, had to be concentrated at the center, in a minute space, not easy to hit -- as a nucleus of almost inconceivable density. The atom, he proposed, must consist overwhelmingly of empty space, with a dense, positively charged nucleus... and a relatively few, negatively charged electrons in orbit about this nucleus -- a miniature solar system, in effect.

Since Sacks has mentioned J.J. Thomson, I would like to call your attention to an aspect of this adventure in science that he has left out of his story HERE. 

...
Chemical change or ionization involved the addition or removal of an electron or two, and this required only a modest energy of two or three electron-volts, such as could be produced easily -- by a chemical reaction, by heat, by light, or by a simple 3-volt battery. But radioactive processes involved the nuclei of atoms, and since these were held together by far greater forces, their disintegration could release energies of far greater magnitude -- some millions of electron-volts.

p290 Soddy coined the term atomic energy soon after the beginning of the twentieth century, ten years or more before the nucleus was discovered. No one had known, or been able to make a remotely plausible guess, as to how the sun and stars could radiate so much energy, and continue to do so for millions of years. Chemical energy would be ludicrously inadequate -- a sun made of coal would burn itself out in ten thousand years. Could radioactivity, atomic energy, provide the answer?

(Footnote: Soddy envisioned... [the] artificial transmutation [of radioactive substances] fifteen years before Rutherford achieved it, and imagined explosive or controlled atomic disintegrations long before fission or fusion were discovered.) He was moved... to rapturous, millennial, and almost mystical heights:

Radium has taught us that there is no limit to the amount of energy in the world. . . . A race which could transmute matter would have little need to earn its bread by the sweat of its brow. . . . Such a race could transform a desert continent, thaw the frozen poles, and make the whole world one smiling Garden of Eden. . . . An entirely new prospect has been opened up. Man’s inheritance has increased, his aspirations have been uplifted, and his destiny has been ennobled to an extent beyond our present power to foretell. . . . One day he will attain the power to regulate for his own purposes the primary fountains of energy which Nature now so jealously conserves for the future.  

Can you get any more Faustian than this? And, again, I'm thinking of that final bit at the very end of Goethe's Faust. 

p291 I read Soddy’s book The Interpretation of Radium in the last year of the war, and I was enraptured by his vision of endless energy, endless light. Soddy’s heady words gave me a sense of the intoxication, the sense of power and redemption, that had attended the discovery of radium and radioactivity at the start of the century.
...

After reading all this I was trying to account for why I was unfamiliar with Soddy's name. Most all of these other scientists I've at least heard of. A quick look at the Wiki bio suggests something Oliver Sacks failed to mention, Soddy may have had a touch of the antisemitism. 


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161. Uncle Tungsten - XIV. The Curies

Jump to Introduction & Chronology
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Uncle Tungsten

Here's a little unrelated bonus
Those of you who have been with me for a while have heard me comment on the annoying habits of crazy people living on our streets -- Foucault's Children, as I like to think of them. Coming home from the market this afternoon I discovered a completely naked man talking to himself at the entrance to my alley and trash strewn from one end of the alley to the other. Last I looked he was still going through his bags of stuff so I expect there will be more litter on the pavement later (I picked-up and put in our trash toters everything at my end of the alley). Just now there was shouting out there as well, which I haven't even bothered to investigate. I don't even know the name of the condition where people obsessively go through their belongings (and optionally change and re-change their clothes.) Would love to know.

Chapter 21 - Madame Curie’s Element

...
p255 Even though the rest of the scientific community had ignored the news of Becquerel’s rays, the Curies [also here] were galvanized by it: this was a phenomenon without precedent or parallel, the revelation of a new, mysterious source of energy; and nobody, apparently, was paying any attention to it. They wondered at once whether there were any substances besides uranium that emitted similar rays, and started on a systematic search (not confined, as Becquerel’s had been, to fluorescent substances) of everything they could lay their hands on, including samples of almost all the seventy known elements in some form or other. They found only one other substance besides uranium that emitted Becquerel’s rays, another element of very high atomic weight -- thorium. Testing a variety of pure uranium and thorium salts, they found the intensity of the radioactivity seemed to be related only to the amount of uranium or thorium present; thus one gram of metallic uranium or thorium was more radioactive than one gram of any of their salts.

p256 But when they extended their survey to some of the common minerals containing uranium and thorium, they found a curious anomaly, for some of these were actually more active than the element itself. Samples of pitchblende, for instance, might be up to four times as radioactive as pure uranium. Could this mean, they wondered, in an inspired leap, that another, as-yet-unknown element was also present in small amounts, one that was far more radioactive than uranium itself?
...
... in July of 1898 they were able to make a bismuth extract [of pitchblende] four hundred times more radioactive than uranium...

...If the existence of this new metal is confirmed we propose to call it polonium... 


They were convinced, moreover, that there must be still another radioactive element waiting to be discovered...

p257 They were unhurried... (They were unaware at the time that there was another eager and intense observer of Becquerel's rays, the brilliant young New Zealander Ernest Rutherford, [1st Baron Rutherford of Nelson] who had come to work in J. J. Thomson’s lab in Cambridge.) ... within six weeks they had a bismuth-free (and presumably polonium-free) barium chloride solution which was nearly a thousand times as radioactive as uranium. [Eugene] Demarcay’s [“the eminent rare-earth spectroscopist”] help was sought... and this time, to their pure joy, he found a spectral line (and later several lines: “two beautiful red bands, one line in the blue-green, and two faint lines in the violet”) belonging to no known element. Emboldened by this, the Curies claimed a second new element a few days before the close of 1898. They decided to call it radium, and since there was only a trace of it mixed in with the barium, they felt its radioactivity “must be enormous.”
...
p259 The Curies had hoped they might isolate radium by 1900, but it was to take nearly four years from the time they announced its probably existence to obtain a pure radium salt, a decigram of radium chloride -- less than a ten-millionth part of the original... fighting (although they did not know it) against the insidious effects of radioactivity on their own bodies, the Curies finally triumphed and obtained a few grains of pure white crystalline radium chloride -- enough to calculate radium’s atomic weight (226), and to give it its rightful place, below barium, in the periodic table.
...
...In 1903, Marie Curie summarized the work of the previous six years in her doctoral thesis, and in the same year she received (with Pierre Curie and Becquerel) the Nobel Prize in physics.
...
p261 I was particularly moved by the description in Eve Curie’s book [their daughter] of how her parents, restless one evening and curious as to how the fractional crystallizations were going, returned to their shed late one night and saw in the darkness a magical glowing everywhere, from all the tubes and vessels and basins containing the radium concentrates, and realized for the first time that their element was spontaneously luminous. The luminosity of phosphorus required the presence of oxygen, but the luminosity of radium arose entirely from within, from its own radioactivity...
...
p262 Uncle Abe still had some radium in his possession, left over from his work on luminous paint, and he would show me this, pulling out a vial with a few milligrams of radium bromide -- it appeared to be a grain of ordinary salt -- at the bottom. He had three little screens painted with platinocyanides -- lithium, sodium, and barium platinocyanide -- and as he waved the tube of radium (gripped in a pair of tongs) near the darkened screens, these lit up suddenly, becoming sheets of red, then yellow, then green fire, each fading suddenly as he moved the tube away again.

...”Radium decomposes the atoms of the air, and then they recombine in different forms -- so you smell ozone and nitrogen peroxide when you are around it. It affects glass -- it turns soft glasses blue, and hard glasses brown...” [That was Uncle Abe] Uncle Abe showed me a piece of fluorspar which he had exposed to radium for a few days. Its original color had been purple, he said, but now it was pale, charged with strange energy. He heated the fluorspar a little, far below red hot, and it suddenly gave off a brilliant flash, as if it were white-hot, and returned to its original purple.
...
p263 I liked to watch Uncle Abe’s radium clock, which was basically a gold-leaf electroscope with a little radium inside. in a separate, thin-walled glass vessel. The radium, emitting negative particles, would gradually get positively charged, and the gold leaves would start to diverge -- until they hit the side of the vessel and got discharged: then the cycle would start all over again. This “clock” had been opening and closing its gold leaves, every three minutes, for more that thirty years, and it would go on doing so for a thousand years or more -- it was the closest thing, Uncle Abe said, to a perpetual motion machine.

Aside from, say, an atom of hydrogen.

...
With radiation of every other sort, going all the way from X-rays to radio waves, energy had to be provided by an external source, but radioactive elements, apparently, had their own power and could emit energy without decrement for months or years, and neither heat nor cold nor pressure nor magnetic fields nor irradiation [?] nor chemical reagents made the least difference to this.

p264 Where did this immense amount of energy come from? The firmest principles in the physical sciences were the principles of conservation -- that matter and energy could neither be created nor destroyed. There had never been any serious suggestion that these principles could ever be violated, and yet radium at first appeared to do exactly that -- to be a perpetuum mobile, a free lunch, a steady and inexhaustible source of energy.
...
p266 With no plausible external source of energy, the Curies were forced to return to their original thought that the energy of radium had to have an internal origin, to be an “atomic property” -- although the basis for this was hardly imaginable. As early as 1898, Marie Curie added a bolder, even outrageous thought, that radioactivity might come from the disintegration of atoms, that it could be “an emission of matter accompanied by a loss of weight of the radioactive substances” [sic -- I would think this should read "an emission of energy..." but this is a quote and I will leave it as is.] -- a hypothesis even more bizarre, it might have seemed, than its alternatives, for it had been axiomatic in science, a fundamental assumption, that atoms were indestructible, immutable, unsplitable -- the whole of chemistry and classical physics was built on this faith. In Maxwell’s words:

p267 Though in the course of ages catastrophes have occurred and may yet occur in the heavens, though ancient systems may be dissolved and new systems evolved out of their ruin, the {atoms} out of which these systems are built -- the foundation stones of the material universe -- remain unbroken and unworn. They continue to this day as they were created -- perfect in number and measure and weight.

All scientific tradition, from Democritus to Dalton, from Lucretius to Maxwell, insisted upon this principle, and one can readily understand how, after her first bold thoughts about atomic disintegration, Marie Curie withdrew from the idea, and (using unusually poetic language) ended her thesis on radium by saying, “the cause of this spontaneous radiation remains a mystery . . . a profound and wonderful enigma.”


Jump to Next: Uncle Tungsten - XV. Transmutation at last