I just finished reading William Cropper’s book Great Physicists, published in 2001 by Oxford University Press. It’s a wonderful book of the life stories of 30 of the leading figures in the field of physics, from Galileo to Stephen Hawking.
I was aware, at least marginally, of most of the people in the book, but I also encountered several surprises. My first surprise was to learn about Sadi Carnot who can, in some respects, be considered the founder of modern thermodynamics. I had never heard of him. But Cropper’s thoughtful discussion of Carnot’s ideas about devices that employ heat to produce power (like the steam engine) convinced me that his work was, indeed, original and important.
I was vaguely familiar with the name of Lise Meitner, but I was truly surprised to learn of the tremendous struggles she endured. She had the misfortune to be both female and Jewish– two disadvantages that did not serve her well during the rise of Nazism. She and her nephew Otto Frisch discovered the process by which a uranium atom could be split in two by a neutron. It was an absolutely stunning idea– one that certainly deserved a Nobel prize– but although her friend and collaborator Otto Hahn won the 1944 Nobel Prize in Chemistry for the discovery of nuclear fission, neither Lise nor her nephew were recognized. She had great difficulty escaping from Nazi Germany during the war, and she met with many barriers to recognition and success after.
I was surprised by the stuffiness of Edwin Hubble who, in later life, exaggerated his wartime bravado (during WWI), his career as a lawyer, and his achievements as an athlete. Apparently he did that to conceal his middle class background from his wife’s wealthy relatives.
I was stunned to learn of the hostility that Sir Arthur Eddington expressed toward Subrahmanyan Chandrasekhar’s deduction that stars larger than about 1.4 time the mass of the Sun cannot collapse into a white dwarf. That rule is now known as the Chandrasekhar Limit, and it has long since been accepted as a fundamental fact about stellar evolution.
I was surprised that Johannes Kepler was not included in the book. In my view, Kepler was a genius of the first rank. But I suppose you can’t write a book about everyone of importance in the history of science.
And I was puzzled and saddened to read that Ludwig Boltzmann committed suicide while he, his wife, and his daughter were traveling near Trieste. He was clearly on the forefront of thermodynamics research at the time, and he was loved as an instructor. But apparently he was also prone to severe bouts of depression.
So many of these stories are full of vitality– and a sense of wonder. That, I suppose, is the main lesson of this book. All of the subjects appear enraptured by their love of the subject. From the indomitable Marie Curie (the only person to win two Nobel prizes in two different subjects), to the casual Albert Einstein to the reclusive Paul Dirac– all of these people exhibit first and foremost a love of the quest, the search for the secrets of nature. That sense of wonder is what I think is most the most enduring lesson of this book. A very good read indeed.
This book, Hen’s Teeth and Horse’s Toes by Stephen Jay Gould, has been sitting unread on my bookshelf for a couple of decades. I finally decided to get around to reading it. I had read an article he wrote many years ago (in Daedalus, I think) and admired it greatly. So I was prepared to be impressed. It was published in 1983.
Mr. Gould taught paleontology and biology at Harvard University. He was also a tremendous writer, and a scholar of the history of biology, geology, and paleontology. This book is a collection of essays he wrote over the course of many years. The topics covered traverse a wide range of issues from his several realms of expertise. Subjects include the parental care habits of boobies, the dazzling originality of Nicolaus Steno’s landmark work Prodromus to a dissertation on a solid body naturally contained within a solid, the asteroid that wiped out the dinosaurs, the “Monkey” trial, the Piltdown conspiracy, the proper classification of Zebras, and the teeth of hens and the toes of horses.
These essays are masterfully written, impeccably documented, and wonderfully diverse. The one element they have in common is the theory of evolution– its principles, its evidence, its elegance, and its many critics. It’s impossible, really, to summarize this book. The subject matter is too broad and the evidence and arguments are too subtle to characterize in a brief overview.
But what emerges unquestionably from these essays is Mr. Gould’s love and mastery of his studies. He was unquestionably a scholar in the highest sense– one who was driven by boundless curiosity and who loved nothing more than learning. These essays are true models of the very best in expository writing on difficult scientific matters. I would encourage anyone to read them.
This book, “Proust and the Squid,” was published in 2007 by Maryanne Wolf. She is a professor of child development at Tufts University where she is also director of the Center for Reading and Language Research.
The title is rather misleading in the respect that although the author provided an interesting analysis of Proust’s writing, she said very little about squids. But it does provide a wonderful history of the invention of writing and of the teaching of both reading and writing. It explains that the human brain has no natural structures that are explicitly designed for reading and that therefore the brain must employ more generic structures to accomplish the amazing feats of both writing and reading.
The history of writing is one of the most fascinating developments in history. The two locales where writing was first invented are ancient Sumer and ancient Egypt. Sumerian writing began as a pictographic system in which written signs represented physical objects such as a house, the sun, or a sheep. But it quickly morphed into what is known as a logographic system in which characters can also represent abstract concepts such as love, anger, or hope.
The Sumerian writing system at first did not represent sounds– but later it evolved to include the sounds of some syllables. In this form it was what is known as a logosyllabary– a writing system that incorporates both logographic images and syllabic sounds. It must have been a very difficult system to master.
The Sumerians also developed a process for teaching the young how to learn this very important tool. We have clear evidence that shows that the Sumerians taught reading with lists of words that were memorized. This was a significant advance in the respect that the Sumerians realized that only the young can carry the knowledge of how to read and write into the future.
This book was written in 2007, and at that time a debate was raging as to whether the Sumerians or the Egyptians were the first to develop a complete writing system. Ms. Wolf presents evidence for the priority of Egypt as follows:
New linguistic evidence, however, suggests that an entirely independent invention of writing in Egypt took place either around 3100 BCE; or, on the basis of still controversial evidence from German Egyptologists in Abydos, as early as 3400 BCE– earlier than the Sumerian script. If this finding proves correct, hieroglyphs would be the first major adaptation in the evolution of the reading brain.
Proust and the Squid, pg. 43
Ms. Wolf devotes an entire chapter to the objections Socrates raised about the propagation of writing. His chief concern was that a written body of text, however erudite, cannot engage in a conversation with its reader. His entire style of teaching– the eponymous technique known as the Socratic method– involved engaging the student in a dialogue, an exchange of ideas, a debate. Written words, Socrates objected, cannot engage the reader in debate and that reading allows citizens to arrive at the wrong conclusions from what they read:
Underneath his ever-present humor and seasoned irony lies a profound fear that literacy without the guidance of a teacher or of a society permits dangerous access to knowledge. Reading presented Socrates with a new version of Pandora’s box: once written language was released there could be no accounting for what would be written, who would read it, or how readers might interpret it.
Proust and the Squid, pg. 77
That observation rings especially true today. The entire QAnon movement was launched by people who found evidence of dark conspiracies lurking behind otherwise ordinary events: a cabal of pedophiles who secretly control the entire world economy from the basement of a pizza parlor in Washington D.C.; space satellites operated by Jews who use them to start forest fires in California; a vast conspiracy of Chinese spies who have infiltrated the deep state and are working tirelessly to turn the entire United States into a Communist gulag. So yes, we have seen and experienced the ill effects of the mass availability of raw data unencumbered by interpretive guidance.
The core of the book is about the actual process of reading. How does the brain actually read anything? Again, the brain doesn’t have any structures that are specifically dedicated to reading. There is no evolutionary reason why humans in hunter-gathering societies would have benefited from reading– and so our genes don’t encode for either reading or writing. Rather, the brain has more abstract pattern matching capabilities– and these have been adapted to the purposes of writing and reading. Ms. Wolf does a wonderful job of relating the latest scientific research (as of 2007) on the subject of the neurobiology of reading. And the astounding fact is that a typical expert reader is able to identify and properly interpret a word in half a second or less. The entire process is one that requires several separate components of the brain– components that work in coordination, some working in parallel– to arrive at an understanding of the thought or story being conveyed by the symbols on the page.
Ms. Wolf also explores cases in which the skill of reading is never fully mastered. What is it that goes wrong? Her answer is that because the process of reading is so complex, and because it involves so many separate brain structures, there are in fact many ways it can go wrong. She provides many interesting examples, along with the wise and compassionate observation that persons with reading disabilities generally have differences in the structures of their brains. They’re not lazy or bored– they’re just different.
I’ll relate an experience of my own. Many years ago I taught high school mathematics classes from pre-algebra through second year calculus. For my geometry classes, I required my students to write a paper– the kind of paper one would write for an English class– but on a topic of mathematics. One year I had a student who was a 9th grader in my Geometry class, putting her roughly one year ahead of where she “should” have been. She was a very good student and was earning an “A” in my class. But when I saw her written paper I was shocked. I couldn’t believe the number and the kinds of spelling errors in her paper! She was the first example of a student with true dyslexia that I had ever encountered. She was decidedly NOT lazy– she just couldn’t spell. I found out that she was working with a special dyslexia tutor. I talked to the tutor and learned that she used a spelling test to determine which students were most likely to benefit from her tutelage.
Ms. Wolf presents a completely different method for diagnosing dyslexia– a speed test. Dyslexic readers are much slower at identifying characters and/or words. I’ll let Ms. Wolf describe her encounter with one such child:
Typically, children who qualify for our study are struggling readers who have been recommended by their teachers, and who have then passed a battery of strenuous tests. Not Luke. He basically recommended himself for our reading intervention. When asked why, he solemnly responded, “I have to read my arias. I can’t memorize them anymore!” Luke, it turned out, sang in the Boston Children’s Opera. He was a gifted singer, but he could no longer keep up with children who could read their lyrics.
Proust and the Squid, pg. 134-135
The book presents a provocative and wonderfully documented analysis of how reading can go wrong– and what can be done about it. And the heartwarming message of this analysis is that the majority of readers with dyslexia can be helped– if they are given the right training.
This is a terrific book. If you don’t believe in dyslexia, if you have dyslexic friends or family members, if you want to understand how the marvelously complex process of reading actually works, or if you want to know something about the history of writing and reading– this book is for you. It is beautifully written and it is chock full of scientific findings– and with hope for the future of treating reading failures.
If dark matter is a type of particle that is subject to gravitation but not to electricity and magnetism, as some physicists have speculated, then such particles should accumulate in the cores of stars. That would mean that a star can achieve the density necessary to kick off nuclear fusion with only about 1/6 the amount of normal matter previously assumed to be necessary, the remaining 5/6 of the star’s total mass being non-interacting dark matter. That would further mean that a star should live no more than about 1/6 as long as would a star of the same total mass comprised of normal matter only. If dark matter does indeed congregate in the cores of stars and if it is truly incapable of participating in nuclear interactions, then it shouldn’t impede the nuclear interactions of normal matter. Additionally, dark matter of this type should not take up much volume. In a neutron star, the neutrons are packed very closely together since the volume of a collection of matter particles is based on electricity & magnetism, particle spin, and the Pauli Exclusion Principle– and neutrons are unaffected by electricity and magnetism. And yet the neutrons still can’t collapse into one another because neutrons have a spin of 1/2 and they are therefore subject to the Pauli Exclusion Principle. In any case stars that consist predominantly of dark matter particles should be much smaller in volume than stars comprised solely of normal matter of the same mass.
The only possible escape I can think of for the above reasoning is the possibility that dark matter particles have no mass. But my assumption has always been that a particle can only exert a gravitational force on other particles if it has mass. If that is not true, then everything that I thought I knew about gravitation goes out the window.
The presence of dark matter in the ratio of 5:1 would have an enormous impact on the composition of the universe. The theory of stellar evolution says that high mass stars burn progressively hotter as they age, and they burn successively higher atomic number atoms, in the following order:
Hydrogen (atomic number 1)
Helium (atomic number 2)
Carbon (atomic number 6)
Oxygen (atomic number 8)
Neon (atomic number 10)
Silicon (atomic number 14)
The burning of silicon results in iron (atomic number 26), and the burning of iron results in a net energy loss to the star– thereby allowing the force of gravitation to overwhelm the outward pressure of radiation, inevitably resulting in the collapse of the star.
If the core of a high mass star is comprised of 83% inert matter, then the result will be a far lower percentage of high atomic number atoms throughout the universe. And that would produce a universe with fewer rocky planets.
Billions of dollars and euros have been spent trying to find dark matter particles. So far all such attempts have failed. Maybe they have failed because dark matter isn’t a type of particle.
We should test the hypothesis that dark matter accumulates in the cores of stars. That wouldn’t necessarily tell us whether dark matter is a type of particle, but it would impose a severe constraint on the type of particle it might be. Unfortunately I don’t know that there’s a way to test for the presence of a lower-than-expected percentage of atoms with an atomic number greater than 2. It seems that would require a survey of the total mass of rocky planets throughout the universe as compared to the mass of the atoms which were present immediately after the period of recombination. That distribution is approximately as follows:
Element
Percent
Hydrogen (H)
~ 75%
4Helium (He)
~ 25%
Deuterium (2H)
~ 0.01%
3Helium (He)
Trace
7Lithium (Li)
Trace
Relative percentages of atoms immediately after the epoch of recombination
(A Universe From Nothing, Lawrence M. Krauss, pg. 111)
Such a survey, so far as I am aware, is beyond our present technology.
Raisin Bread
An analogy often invoked by physicists to explain the expansion of the universe is that of a loaf of raisin bread baking in the oven. As the bread bakes, it rises– and the raisins in the bread move farther apart from each other. Similarly, the matter of the universe, clumped as it is into galaxies, moves apart as the universe expands not because there was a massive explosion that blew matter out in all directions, but because space itself is expanding and the matter of the universe is simply being dragged apart with it as it expands. The raisins represent galaxies, or clusters of galaxies, and all of them are moving away from each other. So from the perspective of an observer in any one galaxy, all other galaxies are moving away.
This analogy raises several questions. First question: What it is that space is expanding into? The space/time of General Relativity has 3 physical and 1 temporal dimensions. If this space/time is expanding into a dimensionless void– a void that has no intrinsic structure of any kind– how is it that our familiar world of space/time gets imposed on that unstructured void? It would seem that there must be some mechanism that enables the creation of the structure of space/time itself.
Exactly what types of structure are able to be imposed on an unstructured void? Would it be possible to have a universe of 47 physical and 17 temporal dimensions? What about fractional dimensions? Or negative dimensions? Could a universe have physical dimensions only and no temporal dimensions?
If instead there are only a very few options for the numbers and types of dimensions in the resulting universe, that would seem to impose a significant constraint on the concept of an unstructured void. And one would have to ask: If an unstructured void has such significant constraints, is it really unstructured?
Second question: Alternatively, if the structure of space/time is expanding into a void that already has the same space/time structure as General Relativity, then what exactly is expanding? Clearly it is not the 3 physical / 1 temporal structure of space/time. Is it simply the outer boundary of our universe? If so, why would the expansion of an outer boundary pull all of the matter of the universe along with it? Einstein famously added the Cosmological Constant to the equations of General Relativity because he wanted a steady state universe– one that was neither expanding nor contracting. Now that we know that the rate of expansion is increasing, some cosmologists have taken to considering the Cosmological Constant as the source of what is termed “Dark Energy.” But Einstein’s original concept of the Cosmological Constant wasn’t about expanding or contracting the boundary of the universe itself. Rather his thought was that the Cosmological Constant acts as a kind of anti-gravity that pushes the physical masses of the universe apart– within the boundaries of the universe.
Perhaps the solution is to re-imagine the Cosmological Constant as a force that propagates the structure of space/time into an undifferentiated void. But wouldn’t that be something different from a force that propels galaxies away from each other? Besides, there is nothing in General Relativity that specifically ties the Cosmological Constant to the propagation of space/time alone.
Third question: If we are explaining the expansion of the universe by an expansion of space/time itself, then wouldn’t that expansion extend all the way down to the atomic and subatomic levels? If so, then the expansion of the universe would be ripping apart every atom– and indeed every composite particle. That type of expansion would have enormous consequences for the evolution of the universe. A star born in the early stages of the universe would live for a much shorter time than a star of the same composition and size created today. That’s because the particles in the core of the star would be much closer together and therefore chemical and nuclear reactions would happen at a much faster rate.
The simplest answer to questions 1 and 2 above is that the 3 physical / 1 temporal structure of the space/time of General Relativity was already imprinted on the void into which the universe expanded at the time of the Big Bang. Of course we have no guarantee that the simplest explanation is the one that is correct, but if true that would mean that the raisin bread metaphor is very misleading. In the raisin bread metaphor, the bread itself (without the raisins) represents the structure of space/time. As the bread expands, space/time expands. But if the void into which the bread is expanding already has the same space/time structure, then it is only the material substance contained within space/time that is expanding, not space/time itself. And if the void already contained the space/time structure of our universe at the time of the Big Bang, then the void should have no boundary at all.
The only test I can think of that would give us a definitive answer to questions 1 and 2 is to actually find a universe with something other than a 3 physical / 1 temporal structure– or to somehow show that no other such structure is possible. But I’m pretty sure that no one has come up with a way to produce either such result.
As for question 3, it seems to me at least possible that it could be submitted to a test. The higher rate expected for nuclear and chemical reactions should show up as higher temperatures for first generation stars. Higher temperature means higher luminosity, and higher luminosity means shorter wavelength. Therefore the spectra of stars from the first generation should be much bluer if indeed space/time itself is what is expanding. Of course these bluer spectra would be red-shifted. So we should be looking for a population of stars with very high red shifts– meaning much older– that have spectra which are unexpectedly bluer than expected. Is such a survey possible? I’m not qualified to answer that question, but my guess is that if it is possible, it would be very hard to do.
David S. Moore: Insights & Innovations 