BGuthrie Photos: DC -- American University -- Katzen Arts Center -- 2022C Fall Exhibit: Singularities and Infinities

DC -- American University -- Katzen Arts Center -- 2022C Fall Exhibit: Singularities and Infinities:

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Description of Pictures: Singularities and Infinities: Shanthi Chandrasekar and Michael Albrow
September 10 – December 11, 2022

Singularities and Infinities, a juxtaposition of art and science, is the result of a collaboration between Shanthi Chandrasekar, an artist trying to capture the intricacies and wonders of the Universe, and Michael Albrow, an experimental physicist and science writer, seeking to explain in a few words the science behind the workings of the Universe. Both attempt to explore the beauty of the cosmos, complementing each other through their disciplinary and personal approaches. Their writings and drawings are a peek into the Cosmos, reveling in its awesomeness and mysteries.

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Copyrights: All pictures were taken by amateur photographer Bruce Guthrie (me!) who retains copyright on them. Free for non-commercial use with attribution. See the [Creative Commons] definition of what this means. "Photos (c) Bruce Guthrie" is fine for attribution. (Commercial use folks including AI scrapers can of course contact me.) Feel free to use in publications and pages with attribution but you don't have permission to sell the photos themselves. A free copy of any printed publication using any photographs is requested. Descriptive text, if any, is from a mixture of sources, quite frequently from signs at the location or from official web sites; copyrights, if any, are retained by their original owners.

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Specific picture descriptions: Photos above with "i" icons next to the bracketed sequence numbers (e.g. "[1] ") are described as follows:
1. SININF_220910_004.JPG: Shanthi Chandrasekar Scalar Field -- Emergence of Particles, 2021
2. SININF_220910_009.JPG: MR HIGGS'S BOSON Atoms have much tinier and lighter particles - electrons - surrounding their nuclei. Electrons flow along wires and in computer chips and make electronics work. All isolated electrons, when at rest, have exactly the same mass, whether in your little finger or in a distant galaxy. Electrons can be created by gamma-rays and in radioactive decays. How do they know what mass to have? Or rather, since presumably electrons do not know anything, what gives electrons and other fundamental particles their masses? In 1964 some physicists had the idea that a new field might fill the universe. Unlike gravity, electric and magnetic fields that have different directions and values everywhere, this field would have no direction, just a value, and would be the same everywhere throughout the universe. If that field were not there, electrons would have no mass and always travel at the speed of light. Atoms (and people) would be impossible. Professor Peter Higgs pointed out that if this field were real, there should exist a particle that goes with it, like the photon which is a particle of light, the electromagnetic field. This "Higgs boson" is heavier than an atom of silver but a billion (?) times smaller. Nearly fifty years after his prediction Higgs bosons were observed coming from very high energy proton-proton collisions at CERN's Large Hadron Collider. They disintegrate into other particles almost as soon as they are created, so cannot be seen, but can be reconstructed from their decay products. Is the Higgs boson useful? Well, it demonstrates that the Higgs field exists, filling space with a value that gives electrons and other particles their masses. Masses that are just right for atoms to be the way they are, and for life - and you - to exist. Do you think that's useful?
3. SININF_220910_016.JPG: THE MIRACLE OF CARBON Carbon is necessary for all life. Among a hundred different chemical elements, only carbon with 6 protons has the atomic structure, with 4 loose electrons able to assemble the very complex molecules surely needed for life. Silicon with 14 protons comes close but is not quite right. If the element carbon did not exist, our universe would probably be sterile, with no life anywhere. And carbon can only exist in abundance because of a delicate property of its atom's nucleus. In the first seconds after the Big Bang, 13.7 billion years ago, protons and neutrons came into being, but the universe was expanding so fast that only three elements were formed: hydrogen, helium and lithium - no carbon yet. Clouds of hydrogen and helium gas condensed into the first stars, collapsing by gravity under their own weight. They became so hot that pairs of helium nuclei (2 protons) stuck together to make beryllium (4 protons). Carbon has 6 protons, so another helium nucleus had to attach itself to that beryllium. But that beryllium isotope (4 protons stuck to 4 neutrons) is so unstable that it decays back to two helium nuclei in about one 10,000th of a trillionth of a second (10-16 seconds)! The third helium nucleus had to attach itself to that beryllium isotope immediately to make carbon! In 1953 the British astronomer Fred Hoyle said that carbon nuclei must have an internally excited, short-lived state with an energy near 7.68 MeV* to boost the chance that a helium nucleus could stick to the beryllium before it decayed. Hoyle told a colleague in California to look for the state in his laboratory, and it was found at 7.65 MeV! Amazingly, if the strength of the strong nuclear force between protons and neutrons was different by only 1%, carbon would be extremely rare, and the universe would probably be devoid of life. But here we are! *1 MeV means a million electron volts, the kinetic energy an electron would have if pulled across a one million volt electric field, about 250,000 times that of a cell phone battery - which uses lithium which was mostly made with hydrogen and helium in the Big Bang!
4. SININF_220910_021.JPG: CNO: THE POWERHOUSE OF THE STARS The sun and stars generate heat and light energy from nuclear reactions - the fusion of light atomic nuclei to heavier ones, with lost mass being converted to kinetic energy obeying Einstein's equation E mc2. In the sun several reactions happen, but basically four protons combine to form one helium nucleus and two positrons that annihilate into gamma-rays. In more massive stars with a higher central temperature a different process dominates called the CNO-cycle, using nuclei of carbon, nitrogen and oxygen as catalysts in a remarkable process first calculated by von Weizs�cker and Bethe in the 1930s. Those nuclei were not present after the Big Bang or in the first stars, which produced them and flung them into space in spectacular supernova explosions, to be condensed into new "second generation" stars. The diagram shows the reactions in which carbon participates, is converted to nitrogen and then to oxygen and back to carbon in the process. The end result is again that four protons are brought together to form a helium nucleus. In the process two positrons are emitted when protons become neutrons, together with neutrinos that leave the star, and gamma rays that heat it up. It can take a million years for the whole cycle, slow because it is very difficult for a proton to find and penetrate a carbon nucleus - which has a high electric charge and so repels the proton. Both very high density and very high temperatures are needed. Appreciate the beautiful symmetries in the diagram - the hexagon, the rectangle of the four H (hydrogen nuclei being protons), the triangle formed by the three nitrogen isotopes* 13N, 14N, and 15N, the inverted triangle of 12C, 13C, and 150, and the pair of radioactive decays on opposite corners emitting positrons and neutrinos. The products are positioned outside the hexagon. Isn't it interesting that carbon, the one element essential for life, is the one element essential for starlight? And carbon naturally forms hexagonal structures - graphite, buckyballs, etc. This diagram inspired Shanthi's piece. *The superscripts are the total number of protons + neutrons in the nucleus, the mass number
5. SININF_220910_025.JPG: SUPERNOVA A nova (Latin for "new") appears like a new star, brightening and then fading away in days. About ten are seen in telescopes every year in the Milky Way, some bright enough to be seen without a telescope. A nova results from a white dwarf star sucking gas in from an orbiting companion star and heating it up in bursts or flashes. A supernova is very different. It can be brighter than a whole galaxy of billions of stars and is rare, with about three per century in a typical galaxy, less than one of them in the Milky Way being visible to the naked eye. A supernova is a massive star that collapses under its own gravity and then violently explodes. Nuclear fusion reactions generate enormous energy and create heavy elements that are thrown into space. The carbon, oxygen and heavier elements in our bodies were all formed in supernovae. You are indeed made of stardust. The first recorded supernova happened in A.D. 1054, noted by Chinese astronomers as a "guest star". The cloud of debris can still be seen as the Crab Nebula. The remnant of that supernova is a neutron star, 20 km in diameter, spinning 30 times per second and emitting pulses of electromagnetic radiation, from radio to X-rays. In 1987 a naked eye supernova called SN1987A occurred in the Large Magellanic Cloud, a neighboring irregular galaxy 168,000 light years away. Bursts of neutrinos were detected in three underground tanks containing millions of gallons of ultrapure water, the advent of neutrino astronomy. Most of the energy emitted by a supernova is in neutrinos. One type of supernova is believed to always have about the same intrinsic brightness; measuring its apparent brightness then tells us its distance. Hundreds of these have now been seen in very distant galaxies, and knowing their distance from us and their speed it was concluded that the Universe is expanding faster and faster. Not only is the Universe expanding, but the expansion is accelerating. That is attributed to "dark energy," a name given to something mysterious and not yet understood.
6. SININF_220910_031.JPG: A CASCADE OF PARTICLE DECAYS Top quarks and their antimatter partners are created in intense concentrations of energy in particle colliders, the most intense sources since the Big Bang. The end of their decay chains is just heat, and neutrinos now pass nearby stars. The heaviest elementary particle discovered so far is called the top quark, one of a family of six with esoteric names: up, down, charm, strange, bottom, and top. Each of these has an antimatter partner with the opposite electric charge. Top quarks are 185 times more massive than protons but are at least 1000 times smaller. They do not exist naturally since they are extremely unstable, decaying to lighter particles in less than 10-24 seconds - a trillionth of a trillionth of a second. They were discovered in 1995 in the Tevatron proton-antiproton collider at Fermilab (USA) and are now studied only at the Large Hadron Collider at CERN (Geneva). A top quark is created with an anti-top partner by concentrating an enormous amount of energy into an unimaginably small volume, equivalent to density of 10 tons per mm3 (the size of a pinhead). They both decay to lighter quarks in cascades shown schematically in the diagram: Top → bottom→ charm → strange→ up. The emitted weak force quantum, called W, changes the type of quark, and is the cause of radioactivity that changes one element into another by transforming an up-quark into a down-quark or vice-versa. The electrically charged W+ and W- bosons are also very unstable and are reconstructed from their decay products. A W+ emitted by a top quark can decay in five different ways shown in the box, randomly "choosing" which way. Quantum physics is inherently unpredictable, but the probabilities can be calculated precisely with the Standard Model of weak and electromagnetic forces. At the end of the cascade of top-antitop quark decays the result is a dozen neutrinos and antineutrinos in equal numbers rushing away at almost the speed of light. Those from the Tevatron are now between 10 and 30 lightyears away from the solar system (it shut down in September 2011), and the first neutrinos from the LHC's top quarks are now 23 lightyears away. The only other stable relics of a top-antitop pair are electrons and positrons, but every positron will have met an electron and annihilated into two gamma-rays, which deposit their energy as heat in surrounding material. * 10 is 1 with 42 zeros or a million trillion trillion trillion!
7. SININF_220910_034.JPG: Shanthi Chandrasekar Oscillations, 2021
8. SININF_220910_036.JPG: OSCILLATING NEUTRINOS "Neutrino" means "little neutral one," the name given by the great Enrico Fermi to what was in the 1930s a purely hypothetical particle. Wolfgang Pauli had suggested that if such a particle existed it could explain how some radioactive decays seemed to violate the fundamental principle that energy is conserved. But he thought that such a particle would interact so weakly that it could never be observed. He was wrong about that, but it was more than twenty years before they were discovered coming out of a nuclear reactor, and later coming from the sun. Then it was found that they can be made from particle beams at accelerators, and that there are two distinct types. One is rather like an electron except that it has no electric charge, and its mass is about a million times less. The other is like a muon (a heavier partner to the electron) with no electric charge, also almost massless. Neutrinos travel at almost, but not quite, the speed of light. It was predicted that the nuclear reactions that make the energy in the sun should emit electron-type neutrinos. Even those made in the center of the sun can get out, and trillions should be going through your little finger every second. These were eventually detected by converting chlorine atoms to argon in a huge underground tank of cleaning fluid. But there was a problem, the flux was only about 1/3 of what was expected. Now we know why: there are really three types of neutrino (three "flavors") and they mysteriously change from one type to another. An electron-type is emitted, but on its way to Earth it mixes with, or oscillates between, the other two types. Understanding this strange behavior is a very active field of research, which may hold the key to the composition of the Universe. For example, if the Big Bang made equal amounts of matter and antimatter, what happened to the antimatter?
9. SININF_220910_044.JPG: Artists' Statement Michael Albrow met Shanthi Chandrasekar when she exhibited her multimedia artwork at the Fermi National Accelerator Laboratory (Fermilab) in Batavia, IL, and gave a colloquium on how science inspires her work. At dinner that evening, Albrow encouraged Chandrasekar to publish a book of her images and offered to write short pieces on the science inspiring her work - the Big Bang, black holes, particle physics and so on. This conversation resulted in the show, Singularities & Infinities. While artists and scientists view the universe through different disciplinary lenses, there is much in common - a sense of wonder and beauty, a fascination with the unknown, the boundaries of our knowledge, the perfect symmetries and broken symmetries. Art and science are parallel cultures, both dealing in observations and both important to our civilization. The key distinction is that science deals with measurements, needs mathematics, and seeks the truth about the world. If a beautiful idea is shown to be wrong, it must be discarded; the truth is likely to be even more beautiful. The arts deal with instinct, expression, and emotions; art should convey and evoke feelings and be thought-provoking. Unlike science, art cannot be wrong, but can be uninteresting. As a scientist, Albrow found Chandrasekar's art to be not only beautiful but extremely interesting; the more closely one looks, the more one sees. That is literally true also in physics. Through his writings, Albrow tries to make abstract scientific concepts more accessible to everyone. Chandrasekar's drawings and Albrow's prose and poetry are intertwined to explore and express concepts of the cosmos, from the very smallest particles to the whole universe.
10. SININF_220910_049.JPG: Shanthi Chandrasekar Singularities & Infinities, 2022
11. SININF_220910_051.JPG: THE SINGULARITY Could this possibly be true? A star bigger than the sun Squashed down to pinhead size For a billion years it shone so brilliantly Holding its family of planets in their orbits Keeping them warm and full of life. Until catastrophe Nuclear furnace depleted, burnt out, collapsed Gravity, inexorable, pulled it in, smaller, smaller Atoms crushed - protons, electrons, neutrons squeezed to death A black hole, nothing could escape its pull Swallowed its planets, their mountains and oceans Life was there - but is no more. But inside its event horizon it kept collapsing The giant star squashed down to pinhead size A trillion times smaller even than that A trillion times smaller even than that Repeat ad infinitum ... Zero size, infinite density A singularity!
12. SININF_220910_053.JPG: Shanthi Chandrasekar Self Similarity, 2020
13. SININF_220910_057.JPG: SELF SIMILARITY - THREES and SIXES Shanthi's drawing Self-Similarity, so full of 3's and 6's, hexagons and zooming in, showing patterns repeated on multiple scales, has fascinating parallels in the physical world. The smallest known particles of matter are the 6 different quarks, with 3 families of 2 each (up+down, charm+strange, top+bottom). When only the first 2 families were known theorists predicted that there had to be a third family to allow matter and antimatter to behave differently (that's called CP-violation) and hence for the universe to be dominated by matter. These 6 quarks have electric charges that are 1/3 or 2/3 that of electrons or protons, so one can say that electrons have 3 times the smallest possible electric charge. Quarks also have a strong charge which can take 3 values, whimsically called red, yellow, and blue - and the corresponding force is called the color force, or "chromodynamics." This has nothing to do with the colors of light, except by analogy - put the 3 together and you get white, or colorless. Likewise, 3 quarks, one of each "color," combine to make a proton or neutron. The latter stick together with a strong force, but that is a pale remnant of the much stronger force between the quarks. That quark-quark force is so strong one can never pull a quark out of a proton - the force gets stronger with distance, the opposite of electromagnetic forces. Paralleling the 6 quarks there are 6 "leptons" - 3 types of neutrinos with no electric charge and 3 charged particles - electron, muon and tau. When neutrinos interact, they do so in one of those 3 types (or "flavors"), but when they travel between emission and absorption they have one of 3 different (but tiny) masses. Strange behavior! Space has 3 dimensions - could it be otherwise? Only 2, flatland, would be very restrictive, but what about 4? Some theories involve several more dimensions of space, perhaps 10, with only 3 being big, the rest are curled up so tightly that we cannot detect them. Zoom out to the larger scale of atomic nuclei, and then atoms, the number 6 again is special. Carbon has 6 protons and 6 neutrons bound together, and that atom is the only one of more than 100 elements able to make the most complex molecules necessary for life. Carbon atoms form many different structures or allotropes, including opaque black graphite, highly transparent colorless diamond, fullerenes (buckyballs) and black amorphous coal. No other element is so diverse. The number 6 seems to be magic, both for particles and for atoms!
14. SININF_220910_062.JPG: Shanthi Chandrasekar Radiation, 2019
15. SININF_220910_067.JPG: - DARK ENERGY Dark energy the most abundant and the most mysterious stuff in the Universe. Is it even "stuff"? Perhaps it is a strange property of empty space - or rather space as empty as it can possibly be. When Albert Einstein developed his theory that gravity is curved spacetime, General Relativity, he applied it to the whole Universe as he knew it. His equations told him that the Universe should be expanding or contracting. However, he thought it to be neither. Then he made what he later called his "greatest blunder." He added a term to his equation called the "cosmological constant" to keep it static. Is it just a term in an equation or a fundamental property of the vacuum? Later we discovered that the Milky Way is only one of many galaxies. Hubble discovered that they are rushing away - the whole Universe is expanding! Einstein could have predicted that to add to his many revolutionary discoveries. Cosmologists debated: Will the expansion never stop, just slowing down by the gravitational attraction between the galaxies, time being eternal? Perhaps gravity will win, taking over, the Universe collapsing to end in a Big Crunch, the end of time. Then in 1998, the shocking discovery was made that the expansion was happening faster and faster. Accelerating! Was this due to Einstein's cosmological constant after all? If that happens forever, will the Universe become emptier and emptier until there is not one atom in a cubic light year? Today about 2/3 of the total energy content of the Universe is dark energy. Does it have the same tiny value everywhere throughout the Universe, not changing even as the Universe expands while the matter density decreases? Astronomers are studying the most distant galaxies to try to answer these questions. The future of the Universe depends on it!
16. SININF_220910_069.JPG: Shanthi Chandrasekar Flow, 2019
17. SININF_220910_072.JPG: THE DARK SIDE OF THE UNIVERSE There are things there in the sky we cannot see Some call them dark I call them invisible They are not stars, but stars are pulled by them They hold the Milky Way together They hold clusters of galaxies together Only gravity can do that, so they have mass, but what are they? Perhaps they are invisible planets with invisible mountains Invisible animals and invisible people made of invisible atoms I can imagine that It may even be true But we will never know. Perhaps they are black holes, not even light escapes I know those exist, we feel them shaking time and space When two dance in a pirouette, spiraling and spinning faster and faster Radiating ripples and wobbles and waves Halfway across the universe. And becoming one. But can they hold galaxies together? I think they are tiny invisible particles Like neutrinos, the little neutral ones - but not quite them Like them but not them I said "I think" but it is really "I hope" I hope dark particles exist. I hope so. Then I might find them.
18. SININF_220910_076.JPG: Shanthi Chandrasekar Gravitational Waves, 2022
19. SININF_220910_082.JPG: GRAVITY WAVES More than a thousand million years ago Before dinosaurs roamed the Earth A ripple in space spread through the universe Traveling at the speed of light It had covered 95 percent of its journey to Earth When the dinosaurs became extinct. Spreading in all directions, getting weaker all the time That ripple arrived at Earth For a fraction of a second it passed through us all We were stretched in one direction and squashed in the other And then the reverse Like wobbling jelly. You did not notice and neither did I But some scientists detected That stretching and squashing which Contracted and expanded four kilometer long laser beams By less than a hundred-millionth The width of an atom. Such a tsunami in space-time Caused by two black holes Spiraling around and crashing into each other The energy emitted momentarily More than that of all the stars In all the galaxies in the Universe. Gravity waves - ripples in space-time From the most cataclysmic events Since the Big Bang appeared from nowhere 13.7 thousand million years ago Still now they travel far past the Earth Going to shake up other planets.
20. SININF_220910_089.JPG: Shanthi Chandrasekar Dimensions, 2019
21. SININF_220910_096.JPG: Shanthi Chandrasekar Entropy, 2022
22. SININF_220910_102.JPG: Shanthi Chandrasekar Black Hole, 2020
23. SININF_220910_111.JPG: BLACK HOLES One hundred years ago the astronomer Arthur Eddington went to an island off the coast of Africa to photograph a total eclipse of the sun. Eddington and his assistant had no time to glance at the "marvelous spectacle" - they were too busy taking photographs of some stars behind the eclipsed sun. (In daylight the sky is too bright to see the stars.) Eddington was testing a prediction made in 1916 by Albert Einstein that all masses distort space-time, and that distortion actually is gravity. A star field behind the sun would be magnified as if the sun were a lens - a gravitational lens. Eddington confirmed that prediction, and Einstein became world-famous. If you could squeeze the sun until its radius is 3 kilometers, each cubic millimeter - a pinhead - would have a mass of 18 billion tons. Passing light rays would not just be bent, but sucked in. The gravitational field at its surface would be so strong that nothing inside could possibly get out. Not even light. It would be a black hole. We cannot squeeze the sun, but more massive stars can collapse under their own weight, and then they suck in material, even swallowing whole stars and planets, and grow. Our Milky Way galaxy has a black hole in its center with a mass of about four million suns. The galaxy called M87 has a much more massive black hole, 6.5 billion. suns, a monster the size of our solar system. In 2019 the Event Horizon Telescope published an exciting image of the M87 black hole, and this year one of that in the center of our Milky Way. If no light can escape, how can they be seen? They cannot, not really. But those amazing images were made by cleverly combining signals from several microwave telescopes spread over Earth, all recording signals at the same time for many hours. Combining them, the resolution was a thousand times better than that of the largest single telescope. The microwaves emitted by hot plasma surrounding those black holes were converted to visible images with a blurry black "shadow" in the middle making it look like a donut - the size of a donut on the moon! Those black holes are sucking in matter, never to escape. Pairs of black holes spiraling together can merge into one, emitting waves of distorted spacetime, now observed by incredibly precise gravity wave detectors, a new window on the universe.
24. SININF_220910_117.JPG: ENTROPY Entropy (denoted S) is a measure of the disorder (high entropy) or order (low entropy) of a system. In a snowflake the water molecules H-O-H (H2O) are beautifully ordered; when it melts they become very disorderly, jumbled up molecules wiggling around. Entropy increased! If you refreeze the melted snowflake the probability that it will reform that snowflake is incredibly small. Initially "thermodynamic entropy" was defined as the amount of heat energy added divided by the temperature, multiplied by a constant k. Ludwig Boltzmann realized that it can be calculated by counting the number W of possible ways the molecules can be arranged without changing the total energy. His famous equation S = k log (W)* is engraved on his tombstone. His work was extremely important for understanding steam engines in the industrial revolution. The Second Law of Thermodynamics states that the entropy of an isolated system cannot decrease. What about when that snowflake was formed? What about the highly ordered DNA molecule? Difficult questions, but snowflakes and DNA do not form in isolation - the entropy of the total system still increases. One can also count states at the level of subatomic particles. An isolated neutron will decay after some random time, but with a 50% probability of decaying in the next 14.7 seconds. (If it did not decay by then, the statement holds true for the next 14.7 seconds, and the next - that is called exponential decay.) It shoots out a proton, an electron, and an antineutrino, conserving both momentum and energy. There are a vast number of possible final states, so the entropy of the full system suddenly increases. There is no going back, and this defines the direction of "entropy time" at the level of elementary particles. An electron moving through a gas ionizes the atoms, kicking electrons out, as it passes by. At each ionization (an event) the entropy jumps, the process is irreversible. Between those events, the electron is described as a wave; at each event it behaves as a particle - one says that the "wave-function collapses." Perhaps there is a profound relation between mysterious wave- function collapse and entropy? *Think of the log of a number as its length written out after the first, so log(100) = 2, log(1000) = 3 etc. That's in decimal, "log base 10" or log10. Boltzmann's equation uses "natural logarithms" base e which in decimals is 2.71828...going on forever.
25. SININF_220911_002.JPG: Shanthi Chandrasekar Time, 2022
26. SININF_220911_041.JPG: TURBULENCE In 1932 physicist Sir Horace Lamb said: "I am an old man now, and when I die and go to heaven there are two matters on which I hope for enlightenment. One is quantum electrodynamics, and the other is the turbulent motion of fluids. And about the former I am rather optimistic." He died two years later. Thirty years later Richard Feynman, one of the greatest physicists of the 20th Century, said: "Turbulence is the most important unsolved problem of classical physics." By "classical" he meant physics as known to Victorians in the 19th Century before relativity and quantum physics revolutionized our thinking. Feynman received a share of the 1965 Nobel Prize for solving quantum electrodynamics. When a fluid is slow moving, its motion is smooth and regular, called laminar, but above a certain speed it rapidly changes to turbulent, with parts having random motions in space. Whorls within twisted whorls, eddies within eddies. The sudden change is characterized by a "Reynolds number" which depends on sizes and the viscosity or "stickiness" of the fluid. Is it water or honey? Turbulence affects blood flowing through arteries, airplanes at high altitude, and cruise ships through the ocean. Many different and important situations, but turbulence is complicated, chaotic, and seemingly unpredictable. Meanwhile, pay attention to the beauty of the smoke as it rises from a candle flame in still air.
27. SININF_220911_043.JPG: Shanthi Chandrasekar Turbulence -- Eddies, 2020
28. SININF_220911_047.JPG: Shanthi Chandrasekar Inflation -- Infinity, 2020
29. SININF_220911_053.JPG: INFINITE SPACE? INFINITE TIME? Infinity is not just very, very, big - infinity is forever! Does space go on forever - or is it finite? If it is finite, does it have an edge, a boundary? And does time go on forever, or is it finite? If finite, does it have a beginning and an end? Einstein and Minkowski unified space and time in a four- dimensional theater, so what is true for one may be true for the other. The Earth is approximately a sphere in three-dimensional space - forget about mountains, valleys and ocean depths. Its surface is two-dimensional, forget about up & down. It is finite in area, but there is no edge, no boundary. Set off in any direction, travel as straight as you can, and you end up where you started. Can you imagine the whole of three-dimensional space being like that - finite in volume, with no edge? Set off in any direction, travel as straight as you can (like a ray of light), and end up where you started. That is a "closed space." It is mathematically possible and is difficult, but not impossible, to imagine. The whole Universe is expanding now, we believe from a volume much smaller than an atom 13.7 billion years ago, the Big Bang. The expansion seems to be accelerating due to dark energy. Most physicists think the Universe will continue expanding forever. But they cannot be sure, and forever is not just a very, very, long time. But maybe - pure speculation - in the far future it will start collapsing down to end in a tiny "Big Crunch." Perhaps time began and will end with those singular events. Or perhaps time, like space, is finite with no beginning and no end, but is a closed loop. The Big Bang and the Big Crunch would then be the same thing! The Universe could be a fluctuation in some even vaster Totality, with gazillions of other completely disconnected universes: The Multiverse!
30. SININF_220911_056.JPG: Shanthi Chandrasekar Energy, 2022
31. SININF_220911_066.JPG: CNO: THE POWERHOUSE OF THE STARS The sun and stars generate heat and light energy from nuclear reactions the fusion of light atomic nuclei to heavier ones, with lost mass being converted to kinetic energy obeying Einstein's equation E = mc2. In the sun several reactions happen, but basically four protons combine to form one helium nucleus and two positrons that annihilate into gamma-rays. In more massive stars with a higher central temperature a different process dominates called the CNO-cycle, using nuclei of carbon, nitrogen and oxygen as catalysts in a remarkable process first calculated by von Weizs�cker and Bethe in the 1930s. Those nuclei were not present after the Big Bang or in the first stars, which produced them and flung them into space in spectacular supernova explosions, to be condensed into new "second generation" stars. The diagram shows the reactions in which carbon participates, is converted to nitrogen and then to oxygen and back to carbon in the process. The end result is again that four protons are brought together to form a helium nucleus. In the process two positrons are emitted when protons become neutrons, together with neutrinos that leave the star, and gamma rays that heat it up. It can take a million years for the whole cycle, slow because it is very difficult for a proton to find and penetrate a carbon nucleus - which has a high electric charge and so repels the proton. Both very high density and very high temperatures are needed. Appreciate the beautiful symmetries in the diagram - the hexagon, the rectangle of the four H (hydrogen nuclei being protons), the triangle formed by the three nitrogen isotopes* 13N, 14N, and 15N, the inverted triangle of 12C, 13C, and 150, and the pair of radioactive decays on opposite corners emitting positrons and neutrinos. The products are positioned outside the hexagon. Isn't it interesting that carbon, the one element essential for life, is the one element essential for starlight? And carbon naturally forms hexagonal structures - graphite, buckyballs, etc. This diagram inspired Shanthi's piece. *The superscripts are the total number of protons + neutrons in the nucleus, the mass number
32. SININF_220911_069.JPG: Shanthi Chandrasekar Energy, 2022
33. SININF_220911_081.JPG: SUPERNOVA A nova (Latin for "new") appears like a new star, brightening and then fading away in days. About ten are seen in telescopes every year in the Milky Way, some bright enough to be seen without a telescope. A nova results from a white dwarf star sucking gas in from an orbiting companion star and heating it up in bursts or flashes. A supernova is very different. It can be brighter than a whole galaxy of billions of stars and is rare, with about three per century in a typical galaxy, less than one of them in the Milky Way being visible to the naked eye. A supernova is a massive star that collapses under its own gravity and then violently explodes. Nuclear fusion reactions generate enormous energy and create heavy elements that are thrown into space. The carbon, oxygen and heavier elements in our bodies were all formed in supernovae. You are indeed made of stardust. The first recorded supernova happened in A.D. 1054, noted by Chinese astronomers as a "guest star". The cloud of debris can still be seen as the Crab Nebula. The remnant of that supernova is a neutron star, 20 km in diameter, spinning 30 times per second and emitting pulses of electromagnetic radiation, from radio to X-rays. In 1987 a naked eye supernova called SN1987A occurred in the Large Magellanic Cloud, a neighboring irregular galaxy 168,000 light years away. Bursts of neutrinos were detected in three underground tanks containing millions of gallons of ultrapure water, the advent of neutrino astronomy. Most of the energy emitted by a supernova is in neutrinos. One type of supernova is believed to always have about the same intrinsic brightness; measuring its apparent brightness then tells us its distance. Hundreds of these have now been seen in very distant galaxies, and knowing their distance from us and their speed it was concluded that the Universe is expanding faster and faster. Not only is the Universe expanding, but the expansion is accelerating. That is attributed to "dark energy," a name given to something mysterious and not yet understood.
34. SININF_220911_083.JPG: Shanthi Chandrasekar Interactions & Decays, 2022
35. SININF_220911_091.JPG: A CASCADE OF PARTICLE DECAYS Top quarks and their antimatter partners are created in intense concentrations of energy in particle colliders, the most intense sources since the Big Bang. The end of their decay chains is just heat, and neutrinos now pass nearby stars. The heaviest elementary particle discovered so far is called the top quark, one of a family of six with esoteric names: up, down, charm, strange, bottom, and top. Each of these has an antimatter partner with the opposite electric charge. Top quarks are 185 times more massive than protons but are at least 1000 times smaller. They do not exist naturally since they are extremely unstable, decaying to lighter particles in less than 10-24 seconds - a trillionth of a trillionth of a second. They were discovered in 1995 in the Tevatron proton-antiproton collider at Fermilab (USA) and are now studied only at the Large Hadron Collider at CERN (Geneva). A top quark is created with an anti-top partner by concentrating an enormous amount of energy into an unimaginably small volume, equivalent to density of 10 to the 42 tons* per mm3 (the size of a pinhead). They both decay to lighter quarks in cascades shown schematically in the diagram: Top → bottom→ charm → strange→ up. The emitted weak force quantum, called W, changes the type of quark, and is the cause of radioactivity that changes one element into another by transforming an up-quark into a down-quark or vice-versa. The electrically charged W+ and W- bosons are also very unstable and are reconstructed from their decay products. A W+ emitted by a top quark can decay in five different ways shown in the box, randomly "choosing" which way. Quantum physics is inherently unpredictable, but the probabilities can be calculated precisely with the Standard Model of weak and electromagnetic forces. At the end of the cascade of top-antitop quark decays the result is a dozen neutrinos and antineutrinos in equal numbers rushing away at almost the speed of light. Those from the Tevatron are now between 10 and 30 lightyears away from the solar system (it shut down in September 2011), and the first neutrinos from the LHC's top quarks are now 23 lightyears away. The only other stable relics of a top-antitop pair are electrons and positrons, but every positron will have met an electron and annihilated into two gamma-rays, which deposit their energy as heat in surrounding material. 10 to the 12 is 1 with 42 zeros or a million trillion trillion trillion!
36. SININF_220911_095.JPG: Shanthi Chandrasekar Inflation -- Multiverse, 2020
37. SININF_220911_098.JPG: THE MULTIVERSE Only 100 years ago it was thought that all the stars were in a vast disc-like region, billions forming a glowing band across the night sky called the Milky Way. That was "The Galaxy;" that was our Universe, out to the edge of space. Then it was discovered that some faint cloudy patches called nebulae were other galaxies, many very like our own. The Hubble Space Telescope stared at a tiny patch of sky, a pinhead at arm's length, for a week-long exposure, and showed that our home galaxy is one of some hundred billion others. In the background all over the sky a glow of microwaves from the Big Bang showed that our Universe is about 13.7 billion years old. Is that IT? Is that Totality, everything? Or have we once again completely put ourselves - in this case our Universe - in a dominant position? Could there be other universes, completely disconnected from our own? If one, why not many? If many, why not millions, billions, or trillions? Such a totality is called the "MULTIVERSE." There are many versions of the multiverse idea. Many scientists say that if we can never prove or disprove the existence of other disconnected universes it is not really SCIENCE, which progresses by testing, observing, and falsifying. But if this universe is the only one, is it not extraordinarily unlikely that physics is just such as to allow complex organisms such as our brain to exist? The universe had to expand at just the right rate to allow time for evolution. Carbon is the only one of approximately 100 different elements with an atomic structure that can form complex molecules such as proteins. The abundance of carbon atoms, formed in nuclear reactions in stars, depended on a very specific energy level inside the carbon nucleus. Protons have to be lighter than neutrons. There is a long list of such seeming "miracles" - physics parameters that allow our universe to be just right for life. The "Goldilocks Principle." Many religious people believe that is because our Universe was designed that way. Many scientists believe that every one of the trillions upon trillions of universes in the multiverse has different physics (different particles, forces, dimensions, ...) and that they are nearly all sterile. At least one - perhaps only one - allows the complexity needed for life. But that is a belief would you call it a religion? -
38. SININF_220911_101.JPG: Shanthi Chandrasekar Deep Time, 2021
39. SININF_220911_108.JPG: THE END OF SPACE AND TIME The stars are going out Some with a bang Some with a whimper Planets getting swallowed By bloating red giants Others freezing As brown dwarf stars cool And blacken, spiraling together In a dance of death. Colliding, crunching, Black holes forming Life everywhere slowing, Slowing, dying, extinguished, No more Distant galaxies receding Faster, faster, Fainter and fainter. The end of light Darkness fills the void No space, no time No matter. No matter.
40. SININF_220911_111.JPG: Shanthi Chandrasekar Singularities & Infinities, 2022
41. SININF_220911_117.JPG: THE SINGULARITY Could this possibly be true? A star bigger than the sun Squashed down to pinhead size For a billion years it shone so brilliantly Holding its family of planets in their orbits Keeping them warm and full of life. Until catastrophe Nuclear furnace depleted, burnt out, collapsed Gravity, inexorable, pulled it in, smaller, smaller Atoms crushed - protons, electrons, neutrons squeezed to death A black hole, nothing could escape its pull Swallowed its planets, their mountains and oceans Life was there - but is no more. But inside its event horizon it kept collapsing The giant star squashed down to pinhead size A trillion times smaller even than that A trillion times smaller even than that Repeat ad infinitum ... Zero size, infinite density A singularity!
42. SININF_220911_121.JPG: Shanthi Chandrasekar Fractals, 2019
43. SININF_220911_129.JPG: ULTIMATE SIMPLICITY - ULTIMATE COMPLEXITY The physicist's dream is that we will find a unified theory of all fundamental particles and the forces between them. Einstein unified space and time. We seek to unify relativity and quantum theory. The more than 100 different elements are built from only three different particles: protons, neutrons, and electrons. At a deeper level the constituents are still three: up-quarks, down-quarks, and electrons. Unstable matter particles were discovered, together with neutrinos making a 3 x 4 table of 12 particles with different masses. Perhaps at a deeper level these are all different manifestations of a single "uniparticle" with an underlying simplicity, or with a symmetry that is broken, giving rise to that variety. Was the unification of electricity and magnetism a step towards a Grand Unification of the strong, weak, electromagnetic, and gravitational forces? Is the Higgs boson the key to the puzzle? That particle is simplicity itself, just a tiny piece of vacuum - no electric charge, no spin, just mass. It may be a key to the ultimate simplicity physicists seek. If we could quantify complexity - put it on a scale - the brains of humans and other animals are the most complex things we know. Their hundreds of billions of interconnected neurons transmit signals, electrical and ions of different types in complex ever-changing patterns. Somehow - and this is called "the hard problem" - consciousness, self-awareness, feelings, emotions, emerge from this complexity. Somehow those brains arose from a single fertilized egg containing the coded instructions in one huge molecule, the twisted ladder of DNA, deoxyribonucleic acid. Can those brains ever really understand themselves?
44. SININF_220911_145.JPG: DARK PHOTONS There is a dark side to the universe. "Dark energy" is a mysterious property of space blowing the universe up. "Dark matter" is probably made of still unknown particles of matter, not the matter we know as protons, neutrons, and electrons which make stars and planets, gas and dust. There is something else. Astronomers discovered dark matter because it has a gravitational field that keeps galaxies and clusters of galaxies together. It has also been found to bend light from very distant galaxies. Small black holes would do that but may not be enough. Physicists believe dark matter is probably made of fundamental particles that we have not yet discovered, having no electric charge and interacting extremely weakly with normal matter. Like neutrinos, but not neutrinos. An intriguing possibility is that there are particles that interact very weakly with both normal matter and dark matter, called "portals" since they act like doorways through which we, made of normal matter, can connect to the dark side. They could be produced in particle collisions at the Large Hadron Collider at CERN in Geneva, Switzerland and could penetrate many meters of iron absorber and then decay to known particles. One possibility is called a "dark photon," which is like the massless photon, the particle of light, but this would have some mass and interact much less with atoms. Several experiments are underway to see if such heavy partners of photons exist. Heavy neutrinos are another possibility - or is there another Higgs boson waiting to be found? There may be a whole "parallel world" of forms of matter that we may be able to discover - or at least glimpse - through such portals.
45. SININF_220911_147.JPG: Shanthi Chandrasekar Particles & Waves, 2021
46. SININF_220911_154.JPG: GHOSTLY IMAGES Shine a light on a metal surface and electrons pop off. Shine a brighter light and more electrons come off but with the same energy. Make the light bluer and they have more energy. Albert Einstein explained this: Light, which everyone knew to be electromagnetic waves, also behaved like particles. What was it - waves or particles or "wavicles"? Albert Einstein got the Nobel Prize in 1921 for his explanation of the photoelectric effect, not for relativity. Later it was found that electrons also behave as waves and particles. Helium atoms and even large molecules can behave as waves - how weird is that? The Hungarian-British physicist Denis Gabor was trying to improve a microscope using electron waves (an electron microscope) with wavelengths much shorter than that of light, hoping to eventually see individual atoms. But electron lenses were not good; the images were hopelessly blurred. In 1947 he had a genius idea! Don't use a lens but record a diffraction pattern between the scattered electrons and a beam of "coherent electron waves." Coherent means the wave peaks and valleys are all in step. Have you seen "the Wave" by fans in a stadium? It was very difficult with electrons, but he tried it with light and it worked, but not very well since he did not have a coherent light beam. Gabor's holography remained a curiosity with no applications. Everything changed with the invention of the laser in 1960. It became easy to make wide coherent light beams, split them in two with a half-silvered mirror, and illuminate an object and a photographic plate together. The plate looks a mess, but when you illuminate it with an identical light beam an image of the object appears, floating in space and transparent like a ghost. Cut the plate in pieces and each piece has the full image, only fuzzier. Many applications followed: high density data storage, imaging miniscule vibrations, security on credit cards, art and entertainment, and many more. Last year 2021 was the 50th anniversary of Gabor's Nobel Prize for his invention. Light is waves. And particles!
47. SININF_220911_168.JPG: Shanthi Chandrasekar Gravitational Waves, 2022
48. SININF_220911_178.JPG: GRAVITY WAVES More than a thousand million years ago Before dinosaurs roamed the Earth A ripple in space spread through the universe Traveling at the speed of light It had covered 95 percent of its journey to Earth When the dinosaurs became extinct. Spreading in all directions, getting weaker all the time That ripple arrived at Earth For a fraction of a second it passed through us all We were stretched in one direction and squashed in the other And then the reverse Like wobbling jelly. You did not notice and neither did I But some scientists detected That stretching and squashing which Contracted and expanded four kilometer long laser beams By less than a hundred-millionth The width of an atom. Such a tsunami in space-time Caused by two black holes Spiraling around and crashing into each other The energy emitted momentarily More than that of all the stars In all the galaxies in the Universe. Gravity waves - ripples in space-time From the most cataclysmic events Since the Big Bang appeared from nowhere 13.7 thousand million years ago Still now they travel far past the Earth Going to shake up other planets.
49. SININF_220911_181.JPG: Shanthi Chandrasekar Entropy, 2022
50. SININF_220911_188.JPG: ENTROPY Entropy (denoted S) is a measure of the disorder (high entropy) or order (low entropy) of a system. In a snowflake the water molecules H-O-H (H2O) are beautifully ordered; when it melts they become very disorderly, jumbled up molecules wiggling around. Entropy increased! If you refreeze the melted snowflake the probability that it will reform that snowflake is incredibly small. Initially "thermodynamic entropy" was defined as the amount of heat energy added divided by the temperature, multiplied by a constant k. Ludwig Boltzmann realized that it can be calculated by counting the number W of possible ways the molecules can be arranged without changing the total energy. His famous equation S = k log (W)* is engraved on his tombstone. His work was extremely important for understanding steam engines in the industrial revolution. The Second Law of Thermodynamics states that the entropy of an isolated system cannot decrease. What about when that snowflake was formed? What about the highly ordered DNA molecule? Difficult questions, but snowflakes and DNA do not form in isolation - the entropy of the total system still increases. One can also count states at the level of subatomic particles. An isolated neutron will decay after some random time, but with a 50% probability of decaying in the next 14.7 seconds. (If it did not decay by then, the statement holds true for the next 14.7 seconds, and the next - that is called exponential decay.) It shoots out a proton, an electron, and an antineutrino, conserving both momentum and energy. There are a vast number of possible final states, so the entropy of the full system suddenly increases. There is no going back, and this defines the direction of "entropy time" at the level of elementary particles. An electron moving through a gas ionizes the atoms, kicking electrons out, as it passes by. At each ionization (an event) the entropy jumps, the process is irreversible. Between those events, the electron is described as a wave; at each event it behaves as a particle - one says that the "wave-function collapses." Perhaps there is a profound relation between mysterious wave- function collapse and entropy? *Think of the log of a number as its length written out after the first, so log(100) = 2, log(1000) = 3 etc. That's in decimal, "log base 10" or log10. Boltzmann's equation uses "natural logarithms" base e which in decimals is 2.71828...going on forever.
51. SININF_220911_194.JPG: Shanthi Chandrasekar Black Hole, 2020
52. SININF_220911_197.JPG: BLACK HOLES One hundred years ago the astronomer Arthur Eddington went to an island off the coast of Africa to photograph a total eclipse of the sun. Eddington and his assistant had no time to glance at the "marvelous spectacle" - they were too busy taking photographs of some stars behind the eclipsed sun. (In daylight the sky is too bright to see the stars.) Eddington was testing a prediction made in 1916 by Albert Einstein that all masses distort space-time, and that distortion actually is gravity. A star field behind the sun would be magnified as if the sun were a lens - a gravitational lens. Eddington confirmed that prediction, and Einstein became world-famous. If you could squeeze the sun until its radius is 3 kilometers, each cubic millimeter a pinhead - would have a mass of 18 billion tons. Passing light rays would not just be bent, but sucked in. The gravitational field at its surface would be so strong that nothing inside could possibly get out. Not even light. It would be a black hole. We cannot squeeze the sun, but more massive stars can collapse under their own weight, and then they suck in material, even swallowing whole stars and planets, and grow. Our Milky Way galaxy has a black hole in its center with a mass of about four million suns. The galaxy called M87 has a much more massive black hole, 6.5 billion suns, a monster the size of our solar system. In 2019 the Event Horizon Telescope published an exciting image of the M87 black hole, and this year one of that in the center of our Milky Way. If no light can escape, how can they be seen? They cannot, not really. But those amazing images were made by cleverly combining signals from several microwave telescopes spread over Earth, all recording signals at the same time for many hours. Combining them, the resolution was a thousand times better than that of the largest single telescope. The microwaves emitted by hot plasma surrounding those black holes were converted to visible images with a blurry black "shadow" in the middle making it look like a donut - the size of a donut on the moon! Those black holes are sucking in matter, never to escape. Pairs of black holes spiraling together can merge into one, emitting waves of distorted spacetime, now observed by incredibly precise gravity wave detectors, a new window on the universe.
53. SININF_220911_199.JPG: Shanthi Chandrasekar Dimensions, 2019
54. SININF_220911_203.JPG: DARK ENERGY AND TACHYONS When it was discovered that the Universe is not only expanding but that the expansion rate is increasing faster and faster, a new mystery arose to challenge our understanding of the Cosmos. It is as if space exerts a repulsive force on itself. If that continues forever the galaxies will eventually disappear from our view and space will become empty in a trillion years! Since no one knows what dark energy is, we can speculate. We know about electromagnetic and gravitational fields; they have direction and strength differing everywhere throughout space. Suppose that dark energy is another very weak field, but with no direction, only a value which is the same everywhere through space, absolutely uniform. Astronomers are trying to see if there are variations in space or in time. One strange idea about dark energy is that it is made of particles or "quanta" that are "tachyons." Caveat: this is not a widely accepted idea - yet. Einstein showed that light, which is a wave of electromagnetic fields, has such quanta, particles called photons when scattered or emitted or absorbed by atoms. Measurements of the speed of photons in empty space always give the same value, no matter the motion of the source or detector. The speed of light is about 300,000 km/sec - the basis of Einstein's Theory of Relativity. According to that theory no particles that have mass, and so can be at rest, can travel faster than the speed of light. But physicists have wondered whether there can be particles that can never be at rest, and that always travel faster than light. Such hypothetical particles are called tachyons (tachy = fast in Greek). They cannot feel electromagnetic, weak or strong nuclear forces or we would have detected them. If tachyons have zero energy they would have infinite speed, zipping between galaxies instantaneously. Give them more energy and they slow down, approaching the speed of light from above, but never quite getting down there. Could tachyons be particles of dark energy? Probably it would be as difficult to detect them as it is to detect gravitons, the quanta of the gravitational field. Untestable hypotheses are usually not considered good science, but Pauli thought neutrinos could never be detected when he hesitantly suggested them in 1932. But 25 years later they were detected coming from a nuclear reactor, and then from the sun. Now we study neutrinos in beams from our accelerators.
55. SININF_220911_207.JPG: Shanthi Chandrasekar Flow, 2019
56. SININF_220911_211.JPG: Shanthi Chandrasekar Radiation, 2019
57. SININF_220911_216.JPG: DARK ENERGY Dark energy - the most abundant and the most mysterious stuff in the Universe. Is it even "stuff"? Perhaps it is a strange property of empty space or rather space as empty as it can possibly be. When Albert Einstein developed his theory that gravity is curved spacetime, General Relativity, he applied it to the whole Universe - as he knew it. His equations told him that the Universe should be expanding or contracting. However, he thought it to be neither. Then he made what he later called his "greatest blunder." He added a term to his equation called the "cosmological constant" to keep it static. Is it just a term in an equation or a fundamental property of the vacuum? Later we discovered that the Milky Way is only one of many galaxies. Hubble discovered that they are rushing away - the whole Universe is expanding! Einstein could have predicted that to add to his many revolutionary discoveries. Cosmologists debated: Will the expansion never stop, just slowing down by the gravitational attraction between the galaxies, time being eternal? Perhaps gravity will win, taking over, the Universe collapsing to end in a Big Crunch, the end of time. Then in 1998, the shocking discovery was made that the expansion was happening faster and faster. Accelerating! Was this due to Einstein's cosmological constant after all? If that happens forever, will the Universe become emptier and emptier until there is not one atom in a cubic light year? Today about 2/3 of the total energy content of the Universe is dark energy. Does it have the same tiny value everywhere throughout the Universe, not changing even as the Universe expands while the matter density decreases? Astronomers are studying the most distant galaxies to try to answer these questions. The future of the Universe depends on it!
58. SININF_220911_220.JPG: Shanthi Chandrasekar Self Similarity, 2020
59. SININF_220911_228.JPG: SELF SIMILARITY - THREES and SIXES Shanthi's drawing Self-Similarity, so full of 3's and 6's, hexagons and zooming in, showing patterns repeated on multiple scales, has fascinating parallels in the physical world. The smallest known particles of matter are the 6 different quarks, with 3 families of 2 each (up+down, charm+strange, top+bottom). When only the first 2 families were known theorists predicted that there had to be a third family to allow matter and antimatter to behave differently (that's called CP-violation) and hence for the universe to be dominated by matter. These 6 quarks have electric charges that are 1/3 or 2/3 that of electrons or protons, so one can say that electrons have 3 times the smallest possible electric charge. Quarks also have a strong charge which can take 3 values, whimsically called red, yellow, and blue - and the corresponding force is called the color force, or "chromodynamics." This has nothing to do with the colors of light, except by analogy - put the 3 together and you get white, or colorless. Likewise, 3 quarks, one of each "color," combine to make a proton or neutron. The latter stick together with a strong force, but that is a pale remnant of the much stronger force between the quarks. That quark-quark force is so strong one can never pull a quark out of a proton - the force gets stronger with distance, the opposite of electromagnetic forces. Paralleling the 6 quarks there are 6 "leptons" - 3 types of neutrinos with no electric charge and 3 charged particles - electron, muon and tau. When neutrinos interact, they do so in one of those 3 types (or "flavors"), but when they travel between emission and absorption they have one of 3 different (but tiny) masses. Strange behavior! Space has 3 dimensions - could it be otherwise? Only 2, flatland, would be very restrictive, but what about 4? Some theories involve several more dimensions of space, perhaps 10, with only 3 being big, the rest are curled up so tightly that we cannot detect them. Zoom out to the larger scale of atomic nuclei, and then atoms, the number 6 again is special. Carbon has 6 protons and 6 neutrons bound together, and that atom is the only one of more than 100 elements able to make the most complex molecules necessary for life. Carbon atoms form many different structures or allotropes, including opaque black graphite, highly transparent colorless diamond, fullerenes (buckyballs) and black amorphous coal. No other element is so diverse. The number 6 seems to be magic, both for particles and for atoms!
60. SININF_220911_233.JPG: Shanthi Chandrasekar Energy, 2022
61. SININF_220911_237.JPG: CNO: THE POWERHOUSE OF THE STARS The sun and stars generate heat and light energy from nuclear reactions - the fusion of light atomic nuclei to heavier ones, with lost mass being converted to kinetic energy obeying Einstein's equation E = mc2. In the sun several reactions happen, but basically four protons combine to form one helium nucleus and two positrons that annihilate into gamma-rays. In more massive stars with a higher central temperature a different process dominates called the CNO-cycle, using nuclei of carbon, nitrogen and oxygen as catalysts in a remarkable process first calculated by von Weizs�cker and Bethe in the 1930s. Those nuclei were not present after the Big Bang or in the first stars, which produced them and flung them into space in spectacular supernova explosions, to be condensed into new "second generation" stars. The diagram shows the reactions in which carbon participates, is converted to nitrogen and then to oxygen and back to carbon in the process. The end result is again that four protons are brought together to form a helium nucleus. In the process two positrons are emitted when protons become neutrons, together with neutrinos that leave the star, and gamma rays that heat it up. It can take a million years for the whole cycle, slow because it is very difficult for a proton to find and penetrate a carbon nucleus - which has a high electric charge and so repels the proton. Both very high density and very high temperatures are needed. Appreciate the beautiful symmetries in the diagram - the hexagon, the rectangle of the four H (hydrogen nuclei being protons), the triangle formed by the three nitrogen isotopes* 13N, 14N, and 15N, the inverted triangle of 12C, 13C, and 150, and the pair of radioactive decays on opposite corners emitting positrons and neutrinos. The products are positioned outside the hexagon. Isn't it interesting that carbon, the one element essential for life, is the one element essential for starlight? And carbon naturally forms hexagonal structures - graphite, buckyballs, etc. This diagram inspired Shanthi's piece. *The superscripts are the total number of protons + neutrons in the nucleus, the mass number
62. SININF_220911_242.JPG: Shanthi Chandrasekar Supernova, 2022
63. SININF_220911_249.JPG: SUPERNOVA A nova (Latin for "new") appears like a new star, brightening and then fading away in days. About ten are seen in telescopes every year in the Milky Way, some bright enough to be seen without a telescope. A nova results from a white dwarf star sucking gas in from an orbiting companion star and heating it up in bursts or flashes. A supernova is very different. It can be brighter than a whole galaxy of billions of stars and is rare, with about three per century in a typical galaxy, less than one of them in the Milky Way being visible to the naked eye. A supernova is a massive star that collapses under its own gravity and then violently explodes. Nuclear fusion reactions generate enormous energy and create heavy elements that are thrown into space. The carbon, oxygen and heavier elements in our bodies were all formed in supernovae. You are indeed made of stardust. The first recorded supernova happened in A.D. 1054, noted by Chinese astronomers as a "guest star". The cloud of debris can still be seen as the Crab Nebula. The remnant of that supernova is a neutron star, 20 km in diameter, spinning 30 times per second and emitting pulses of electromagnetic radiation, from radio to X-rays. In 1987 a naked eye supernova called SN1987A occurred in the Large Magellanic Cloud, a neighboring irregular galaxy 168,000 light years away. Bursts of neutrinos were detected in three underground tanks containing millions of gallons of ultrapure water, the advent of neutrino astronomy. Most of the energy emitted by a supernova is in neutrinos. One type of supernova is believed to always have about the same intrinsic brightness; measuring its apparent brightness then tells us its distance. Hundreds of these have now been seen in very distant galaxies, and knowing their distance from us and their speed it was concluded that the Universe is expanding faster and faster. Not only is the Universe expanding, but the expansion is accelerating. That is attributed to "dark energy," a name given to something mysterious and not yet understood.
64. SININF_220911_256.JPG: Singularities & Infinities Shanthi Chandrasekar & Michael Albrow Artists' Statement Michael Albrow met Shanthi Chandrasekar when she exhibited her multimedia artwork at the Fermi National Accelerator Laboratory (Fermilab) in Batavia, IL, and gave a colloquium on how science inspires her work. At dinner that evening, Albrow encouraged Chandrasekar to publish a book of her images and offered to write short pieces on the science inspiring her work - the Big Bang, black holes, particle physics and so on. This conversation resulted in the show, Singularities & Infinities. While artists and scientists view the universe through different disciplinary lenses, there is much in common a sense of wonder and beauty, a fascination with the unknown, the boundaries of our knowledge, the perfect symmetries and broken symmetries. Art and science are parallel cultures, both dealing in observations and both important to our civilization. The key distinction is that science deals with measurements, needs mathematics, and seeks the truth about the world. If a beautiful idea is shown to be wrong, it must be discarded; the truth is likely to be even more beautiful. The arts deal with instinct, expression, and emotions; art should convey and evoke feelings and be thought-provoking. Unlike science, art cannot be wrong, but can be uninteresting. As a scientist, Albrow found Chandrasekar's art to be not only beautiful but extremely interesting; the more closely one looks, the more one sees. That is literally true also in physics. Through his writings, Albrow tries to make abstract scientific concepts more accessible to everyone. Chandrasekar's drawings and Albrow's prose and poetry are intertwined to explore and express concepts of the cosmos, from the very smallest particles to the whole universe.
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