Rob Hopkins reminds us that the oil our world depends on is steadily running out. He proposes a unique solution to this problem -- the Transition response, where we prepare ourselves for life without oil and sacrifice our luxuries to build systems and communities that are completely independent of fossil fuels.
Saturday, March 20, 2010
Wednesday, December 23, 2009
Nuclear Fusion
Physicist Steven Cowley is certain that nuclear fusion is the only truly sustainable solution to the fuel crisis. He explains why fusion will work -- and details the projects that he and many others have devoted their lives to, working against the clock to create a new source of energy.
Friday, October 30, 2009
Navigating Our Global Future
As globalization and technological advances bring us hurtling towards a new integrated future, Ian Goldin warns that not all people may benefit equally. But, he says, if we can recognize this danger, we might yet realize the possibility of improved life for everyone.
Tuesday, October 27, 2009
Explaining Explanation
For tens of thousands of years our ancestors understood the world through myths, and the pace of change was glacial. The rise of scientific understanding transformed the world within a few centuries. Why? Physicist David Deutsch proposes a subtle answer
Monday, April 27, 2009
Colors
[condensed from Chapter 3, The Embodied Mind, of “Philosophy In The Flesh”, by George Lakoff and Mark Johnson, published by Basic Books, 1999]
We are neural beings. Each human brain has 100 billion neurons and 100 trillion synaptic connections. It is common in the brain for information to be passed from one dense ensemble of neurons to another via a relatively sparse set of connections.
To take a concrete example, each human eye has 100 million light-sensing cells, but only about 1 million fibers leading to the brain. Each incoming image must therefore be reduced in complexity by a factor of 100. That is, information in each fiber constitutes a “categorization” of the information from about 100 cells. Neural categorization of this sort exists throughout the brain, up through the highest level of categories that we can be aware of. When we see trees, we see them as trees, not just as individual objects distinct from one another. The same with rocks, houses, windows, doors, and so on.
Since we are neural beings, our categories are formed through our embodiment. What that means is that the categories we form are part of our experience. What we call concepts are neural structures that allow us to mentally characterize our categories and reason about them.
What could be simpler or more obvious than color concepts? The sky is blue, fresh grass is green, blood is red, the sun and moon are yellow. We see color, and yet it is false, as false as another thing we see, the moving sun rising past the edge of the stationary earth.
Our experience of color is created by a combination of four factors: wavelengths of reflected light, lighting conditions, and two aspects of our bodies: (1) the three kinds of color cones in our retinas which absorb light of long, medium, and short wavelengths, and (2) the complex neural circuitry connected to those cones.
However, one physical property of the surface of an object matters for color: its reflectance, that is, the relative percentages of high-, medium-, and low-frequency light that it reflects. That is a constant. But the actual wavelengths of light reflected by an object are not a constant.
The wavelengths of light coming from an object depend on the nature of the light illuminating it: tungsten or fluorescent, daylight on a sunny or on a cloudy day, the light of dawn or dusk. Under different conditions, the wavelengths of light coming from an object will differ considerably, yet its color will be relatively constant, it will look pretty much the same. Color, then is not just the perception of wavelength; color constancy depends on the brain´s ability to compensate for variations in the light source.
Another crucial thing to bear in mind is that light is not colored. Visible light is electromagnetic radiation, like radio waves, vibrating within a certain frequency range, and only when such radiation impinges on our retinas are we able to see. We see a particular color when the surrounding conditions are right, when radiation in a certain range impinges on our retina and when our color cones absorb the radiation, producing an electric signal that is appropriately processed by the neural circuitry of our brains. The qualitative experience that this produces in us is what we call “color”.
Colors as we see them, say, the red of blood or the blue of the sky, are not out there in the blood or the sky. Indeed, the sky is not even an object. It has no surface for the color to be in. Without a physical surface, the sky does not have a surface reflectance to be detected as color. The sky is blue because the atmosphere transmits only a certain range of wavelengths of incoming light from the sun, and of the wavelengths it does transmit, it scatters some more than others. Thus, the sky is blue for a very different reason than a painting of the sky is blue. What we perceive as blue does not characterize a single “thing” in the world, neither “blueness” nor wavelength reflectance.
Color concepts are “interactional”; they arise from the interactions of our bodies, our brains, the reflective properties of objects, and electromagnetic radiation. Colors are not objective; there is in the grass or the sky no greenness or blueness independent of retinas, color cones, neural circuitry, and brains. Nor are colors purely subjective; they are neither a figment of our imaginations nor spontaneous creations of our brains.
Evolution has worked with physical limitations: only certain wavelengths of light get through the atmosphere, only certain chemicals react to short, medium, and long wavelengths, and so on. We have the color concepts we do because the physical limitations constraining evolution gave evolutionary advantages to beings with a color system that enabled them to function well in cucial aspects. We have evolved within these limitations to have the color systems we have, and they allow us to function well in the world.
Wednesday, January 7, 2009
The Persistence of Memory
From Carl Sagan’s “Cosmos, The Book”, Chapter 11, (Ballantyne Books paperback edition Nov.1985, pages 227-231).
“…..The information stored in the DNA double helix of a whale or a human or of any other beast or vegetable on earth is written in a language of four letters – the four different kinds of nucleotides, the molecular components that make up DNA. How many bits of information are contained on the hereditary material of various life forms? How many yes/no answers to the various biological questions are written in the language of life? A virus needs about 10,000 bits – roughly equivalent to the amount of information on a full page. But the viral information is simple, exceeding compact, extraordinarily efficient. Reading it requires very close attention. These are the instructions it needs to infect some other organism and to reproduce itself – the only things that viruses are any good at. A bacterium uses roughly a million bits of information – which is about 100 printed pages. Bacteria have a lot more to do than viruses. Unlike the viruses, they are not thoroughgoing parasites. Bacteria have to make a living. And a free-swimming one-celled amoeba is much more sophisticated; with about four hundred million bits in its DNA, it would require some eighty 500-page volumes to make another amoeba.
A whale or a human being needs something like five billion bits. These bits of information in our encyclopaedia of life – in the nucleus of each of our cells – if written out in, say, English, would fill a thousand volumes. Every one of your hundred trillion cells contains a complete library of instructions on how to make every part of you. Every cell in your body arises by successive cell divisions from a single cell, a fertilized egg generated by your parents. Every time that cell divided, in the many embryological steps that went into making you, the original set of genetic instructions was duplicated with great fidelity. So your liver cells have some unemployed knowledge about how to make your bone cells, and vice-versa. The genetic library contains everything your body knows how to do on its own. The ancient information is written in exhaustive, careful redundant detail – how to laugh, how to sneeze, how to walk, how to recognize patterns, how to reproduce, how to digest an apple.
Eating an apple is an immensely complicated process. In fact, if I had to synthesize my own enzymes, if I consciously had to remember and direct all the chemical steps required to get energy out of food, I would probably starve. But even bacteria do anaerobic glycolysis, which is why apples rot: lunchtime for the microbes. They and we and all creatures in between possess many similar genetic instructions. Our separate gene libraries have many pages in common, another reminder of our common evolutionary heritage. Our technology can duplicate only a tiny fraction of the intricate biochemistry that our bodies effortlessly perform: we have only just begun to study these processes. Evolution, however, has had billions of years of practice. DNA knows.
But suppose what you had to do was so complicated that even several billion bits was insufficient. Suppose the environment was changing so fast that the pre-coded genetic encyclopaedia, which served perfectly well before, was no longer entirely adequate. Then even a gene library of 1,000 volumes would not be enough. That is why we have brains.
Like all our organs, the brain has evolved, increasing in complexity and information content, over millions of years. Its structure reflects all the stages through which it has passed. This brain evolved from the inside out. Deep inside is the oldest part, the brainstem, which conducts the basic biological functions, including the rhythms of life – heartbeat and respiration. According to a provocative insight by Paul Maclean, the higher functions of the brain evolved in three successive stages. Capping the brainstem is the R-complex, the seat of aggression, ritual, territoriality and social hierarchy, which evolved hundreds of millions years ago in our reptilian ancestors. Deep inside the skull of every one of us there is something like the brain of a crocodile. Surrounding the R-complex is the limbic system or mammalian brain, which evolved tens of millions of years ago in ancestors who were mammals but not yet primates. It is a major source of our moods and emotions, of our concern and care for the young.
And finally, on the outside, living in uneasy truce with the more primitive brains beneath, is the cerebral cortex, which evolved millions of years ago in our primate ancestors. The cerebral cortex, where matter is transformed into consciousness, is the point of embarkation for all our cosmic voyages. Comprising more than two thirds of the brain mass, it is the realm of both intuition and critical analysis. It is here that we have ideas and inspirations, here that we read and write, here that we do mathematics and compose music. The cortex regulates our conscious lives. It is the distinction of our species, the seat of our humanity. Civilization is the product of the cerebral cortex.
The language of the brain is not the DNA language of the genes. Rather, what we know is encoded in cells called neurons – microscopic electrochemical switching elements, typically a few hundredths of a millimeter across. Each of us has perhaps a hundred billion neurons, comparable to the number of stars in the Milky Way Galaxy. Many neurons have thousands of connections to their neighbors. There is something like a hundred trillion such connections in the human cerebral cortex.”
“…..The information content of the human brain expressed in bits is probably comparable to the total number of connections among the neurons – about a hundred trillion bits. If written out in English, say, that information would fill some twenty million volumes, as many as in the world’s largest libraries. The equivalent of twenty million books is inside the heads of every one of us. The brain is a very big place in a very small space. Most of the books in the brain are in the cerebral cortex. Down in the basement are the functions our remote ancestors mainly depended on – aggression, child-rearing, fear, sex, the willingness to follow leaders blindly. Of the higher brain functions – reading, writing, speaking – seem to be localized in particular places in the cerebral cortex. Memories, on the other hand, are stored redundantly in many locales…….”
“…..The brain does much more than recollect. It compares, synthesizes, analyzes, generates abstractions. We must figure out much more than our genes can know. That is why the brain library is some ten thousand times larger than the gene library. Our passion for learning, evident in the behavior of every toddler, is the tool for our survival. Emotions and ritualized behavior patterns are built deeply into us. They are part of our humanity. But they are not characteristically human. Many other animals have feelings. What distinguishes our species is thought. The cerebral cortex is a liberation. We need no longer be trapped in the genetically inherited behavior patterns of lizards and baboons. We are, each of us, largely responsible for what gets put into our brains, for what, as adults, we wind up caring for and knowing about. No longer at the mercy of the reptile brain, we can change ourselves.”
“…..The information stored in the DNA double helix of a whale or a human or of any other beast or vegetable on earth is written in a language of four letters – the four different kinds of nucleotides, the molecular components that make up DNA. How many bits of information are contained on the hereditary material of various life forms? How many yes/no answers to the various biological questions are written in the language of life? A virus needs about 10,000 bits – roughly equivalent to the amount of information on a full page. But the viral information is simple, exceeding compact, extraordinarily efficient. Reading it requires very close attention. These are the instructions it needs to infect some other organism and to reproduce itself – the only things that viruses are any good at. A bacterium uses roughly a million bits of information – which is about 100 printed pages. Bacteria have a lot more to do than viruses. Unlike the viruses, they are not thoroughgoing parasites. Bacteria have to make a living. And a free-swimming one-celled amoeba is much more sophisticated; with about four hundred million bits in its DNA, it would require some eighty 500-page volumes to make another amoeba.
A whale or a human being needs something like five billion bits. These bits of information in our encyclopaedia of life – in the nucleus of each of our cells – if written out in, say, English, would fill a thousand volumes. Every one of your hundred trillion cells contains a complete library of instructions on how to make every part of you. Every cell in your body arises by successive cell divisions from a single cell, a fertilized egg generated by your parents. Every time that cell divided, in the many embryological steps that went into making you, the original set of genetic instructions was duplicated with great fidelity. So your liver cells have some unemployed knowledge about how to make your bone cells, and vice-versa. The genetic library contains everything your body knows how to do on its own. The ancient information is written in exhaustive, careful redundant detail – how to laugh, how to sneeze, how to walk, how to recognize patterns, how to reproduce, how to digest an apple.
Eating an apple is an immensely complicated process. In fact, if I had to synthesize my own enzymes, if I consciously had to remember and direct all the chemical steps required to get energy out of food, I would probably starve. But even bacteria do anaerobic glycolysis, which is why apples rot: lunchtime for the microbes. They and we and all creatures in between possess many similar genetic instructions. Our separate gene libraries have many pages in common, another reminder of our common evolutionary heritage. Our technology can duplicate only a tiny fraction of the intricate biochemistry that our bodies effortlessly perform: we have only just begun to study these processes. Evolution, however, has had billions of years of practice. DNA knows.
But suppose what you had to do was so complicated that even several billion bits was insufficient. Suppose the environment was changing so fast that the pre-coded genetic encyclopaedia, which served perfectly well before, was no longer entirely adequate. Then even a gene library of 1,000 volumes would not be enough. That is why we have brains.
Like all our organs, the brain has evolved, increasing in complexity and information content, over millions of years. Its structure reflects all the stages through which it has passed. This brain evolved from the inside out. Deep inside is the oldest part, the brainstem, which conducts the basic biological functions, including the rhythms of life – heartbeat and respiration. According to a provocative insight by Paul Maclean, the higher functions of the brain evolved in three successive stages. Capping the brainstem is the R-complex, the seat of aggression, ritual, territoriality and social hierarchy, which evolved hundreds of millions years ago in our reptilian ancestors. Deep inside the skull of every one of us there is something like the brain of a crocodile. Surrounding the R-complex is the limbic system or mammalian brain, which evolved tens of millions of years ago in ancestors who were mammals but not yet primates. It is a major source of our moods and emotions, of our concern and care for the young.
And finally, on the outside, living in uneasy truce with the more primitive brains beneath, is the cerebral cortex, which evolved millions of years ago in our primate ancestors. The cerebral cortex, where matter is transformed into consciousness, is the point of embarkation for all our cosmic voyages. Comprising more than two thirds of the brain mass, it is the realm of both intuition and critical analysis. It is here that we have ideas and inspirations, here that we read and write, here that we do mathematics and compose music. The cortex regulates our conscious lives. It is the distinction of our species, the seat of our humanity. Civilization is the product of the cerebral cortex.
The language of the brain is not the DNA language of the genes. Rather, what we know is encoded in cells called neurons – microscopic electrochemical switching elements, typically a few hundredths of a millimeter across. Each of us has perhaps a hundred billion neurons, comparable to the number of stars in the Milky Way Galaxy. Many neurons have thousands of connections to their neighbors. There is something like a hundred trillion such connections in the human cerebral cortex.”
“…..The information content of the human brain expressed in bits is probably comparable to the total number of connections among the neurons – about a hundred trillion bits. If written out in English, say, that information would fill some twenty million volumes, as many as in the world’s largest libraries. The equivalent of twenty million books is inside the heads of every one of us. The brain is a very big place in a very small space. Most of the books in the brain are in the cerebral cortex. Down in the basement are the functions our remote ancestors mainly depended on – aggression, child-rearing, fear, sex, the willingness to follow leaders blindly. Of the higher brain functions – reading, writing, speaking – seem to be localized in particular places in the cerebral cortex. Memories, on the other hand, are stored redundantly in many locales…….”
“…..The brain does much more than recollect. It compares, synthesizes, analyzes, generates abstractions. We must figure out much more than our genes can know. That is why the brain library is some ten thousand times larger than the gene library. Our passion for learning, evident in the behavior of every toddler, is the tool for our survival. Emotions and ritualized behavior patterns are built deeply into us. They are part of our humanity. But they are not characteristically human. Many other animals have feelings. What distinguishes our species is thought. The cerebral cortex is a liberation. We need no longer be trapped in the genetically inherited behavior patterns of lizards and baboons. We are, each of us, largely responsible for what gets put into our brains, for what, as adults, we wind up caring for and knowing about. No longer at the mercy of the reptile brain, we can change ourselves.”
The Natural Sciences
From Edward O. Wilson’s “Consilience: The Unity of Knowledge”, chapter 4, pp.45-48
“….Without the instruments and accumulated knowledge of the natural sciences – physics, chemistry and biology – humans are trapped in a cognitive prison. They are like intelligent fish born in a deep, shadowed pool. Wondering and restless, longing to reach out, they think about the world outside. They invent ingenious speculations and myths about the origin of the confining waters, of the sun and the sky and the stars above, and the meaning of their own existence. But they are wrong, always wrong, because the world is too remote from ordinary experience to be merely imagined……
With instrumental science humanity has escaped confinement and prodigiously extended its grasp of physical reality. Once we were nearly blind, now we can see – literally. Visible light, we have learned, is not the sole illuminating energy of the universe, as pre-scientific common sense decreed. It is instead an infinitesimal sliver of electromagnetic radiation, comprising wavelengths of 400 to 700 nanometers (billionths of a meter), within a spectrum that ranges from gamma waves trillions of times shorter to radio waves trillions of times longer. Radiation over this span, in wildly varying amounts, continually rain down on our bodies. But without instruments we were oblivious to its existence. Because the human retina is rigged to report only 400 to 700 nanometers, the unaided brain concludes that only visible light exists.
Many kinds of animals know better. They live in a different visual world, oblivious to part of the human visible spectrum, sensitive to some wavelengths outside it. Below 400 nanometers, butterflies find flowers and pinpoint pollen and nectar sources by the pattern of ultraviolet rays reflected off the petals. Where we see a plain yellow or white blossom, they see spots and concentric circles in light and dark. The patterns have evolved in plants to guide insect pollinators to the anthers and nectar pools.
With the aid of appropriate instruments we can now see the world with butterfly eyes.
Scientists have entered the visual world of animals and beyond because they understand the electromagnetic spectrum. They can translate any wavelength into visible light and audible sound and generate most of the spectrum from diverse energy sources. By manipulating selected segments of the electromagnetic spectrum they peer downward to the trajectories of sub-atomic particles and outward to star birth in distant galaxies whose incoming light dates back to near the beginning of the universe. They (more accurately we, since scientific knowledge is universally available) can visualize matter across thirty seven orders of magnitude. The largest galactic cluster is larger than the smallest known particle by a factor of one with about thirty-seven zeroes following it.
I mean no disrespect when I say that pre-scientific people, regardless of their innate genius, could never guess the physical reality beyond the tiny sphere attainable by unaided common sense……and notwithstanding the emotional satisfaction it gives, mysticism, the strongest pre-scientific probe into the unknown, has yielded zero. No shaman’s spell or fast upon a sacred mountain can summon the electromagnetic spectrum. Prophets of the great religions were kept unaware of its existence, not because of a secretive god but because they lacked the hard-won knowledge of physics………
All our other senses have been expanded by science. Once we were deaf; now we can hear everything. The human auditory range is 20 to 20,000 Hz, or cycles of air compression per second. Above that range, flying bats broadcast ultrasonic pulses into the night air and listen to echoes to locate moths and other insects on the wing. Many of their potential prey listen with ears tuned to the same frequencies as the bats……..
We have even uncovered basic senses entirely outside the human repertory. Where humans detect electricity only indirectly by a tingling of skin or flash of light, the electric fishes of Africa or South America, a medley of freshwater eels, catfish, and elephant-nosed fishes, live in a galvanic world. They generate charged fields around their bodies with trunk muscle tissue that has been modified by evolution into organic batteries……They also communicate with one another by means of coded electrical bursts. Zoologists, using generators and detectors, can join the conversation. They are able to talk as through a fish’s skin.
From these and countless other examples can be drawn an informal rule of biological evolution important to the understanding of the human condition: if an organic sensor can be imagined that picks up any signal from the environment, there exists a species somewhere that possesses it. The bountiful powers of life expressed in such diversity raise a question about the incapacity of the unaided human senses. Why can’t our species, the supposed summum bonum of Creation, do as much as all the animals combined, and more? Why were we brought into the world physically handicapped?
Evolutionary biology offers a simple answer. Natural selection……prepares organisms only for necessities…..It follows that each species lives in its own sensory world.…….Natural selection, in short, does not anticipate future needs. But this principle, while explaining so much so well, presents a difficulty. If the principle is universally true, how did natural selection prepare the mind for civilization before civilization existed? That is the great mystery of human evolution: how to account for calculus and Mozart.
“….Without the instruments and accumulated knowledge of the natural sciences – physics, chemistry and biology – humans are trapped in a cognitive prison. They are like intelligent fish born in a deep, shadowed pool. Wondering and restless, longing to reach out, they think about the world outside. They invent ingenious speculations and myths about the origin of the confining waters, of the sun and the sky and the stars above, and the meaning of their own existence. But they are wrong, always wrong, because the world is too remote from ordinary experience to be merely imagined……
With instrumental science humanity has escaped confinement and prodigiously extended its grasp of physical reality. Once we were nearly blind, now we can see – literally. Visible light, we have learned, is not the sole illuminating energy of the universe, as pre-scientific common sense decreed. It is instead an infinitesimal sliver of electromagnetic radiation, comprising wavelengths of 400 to 700 nanometers (billionths of a meter), within a spectrum that ranges from gamma waves trillions of times shorter to radio waves trillions of times longer. Radiation over this span, in wildly varying amounts, continually rain down on our bodies. But without instruments we were oblivious to its existence. Because the human retina is rigged to report only 400 to 700 nanometers, the unaided brain concludes that only visible light exists.
Many kinds of animals know better. They live in a different visual world, oblivious to part of the human visible spectrum, sensitive to some wavelengths outside it. Below 400 nanometers, butterflies find flowers and pinpoint pollen and nectar sources by the pattern of ultraviolet rays reflected off the petals. Where we see a plain yellow or white blossom, they see spots and concentric circles in light and dark. The patterns have evolved in plants to guide insect pollinators to the anthers and nectar pools.
With the aid of appropriate instruments we can now see the world with butterfly eyes.
Scientists have entered the visual world of animals and beyond because they understand the electromagnetic spectrum. They can translate any wavelength into visible light and audible sound and generate most of the spectrum from diverse energy sources. By manipulating selected segments of the electromagnetic spectrum they peer downward to the trajectories of sub-atomic particles and outward to star birth in distant galaxies whose incoming light dates back to near the beginning of the universe. They (more accurately we, since scientific knowledge is universally available) can visualize matter across thirty seven orders of magnitude. The largest galactic cluster is larger than the smallest known particle by a factor of one with about thirty-seven zeroes following it.
I mean no disrespect when I say that pre-scientific people, regardless of their innate genius, could never guess the physical reality beyond the tiny sphere attainable by unaided common sense……and notwithstanding the emotional satisfaction it gives, mysticism, the strongest pre-scientific probe into the unknown, has yielded zero. No shaman’s spell or fast upon a sacred mountain can summon the electromagnetic spectrum. Prophets of the great religions were kept unaware of its existence, not because of a secretive god but because they lacked the hard-won knowledge of physics………
All our other senses have been expanded by science. Once we were deaf; now we can hear everything. The human auditory range is 20 to 20,000 Hz, or cycles of air compression per second. Above that range, flying bats broadcast ultrasonic pulses into the night air and listen to echoes to locate moths and other insects on the wing. Many of their potential prey listen with ears tuned to the same frequencies as the bats……..
We have even uncovered basic senses entirely outside the human repertory. Where humans detect electricity only indirectly by a tingling of skin or flash of light, the electric fishes of Africa or South America, a medley of freshwater eels, catfish, and elephant-nosed fishes, live in a galvanic world. They generate charged fields around their bodies with trunk muscle tissue that has been modified by evolution into organic batteries……They also communicate with one another by means of coded electrical bursts. Zoologists, using generators and detectors, can join the conversation. They are able to talk as through a fish’s skin.
From these and countless other examples can be drawn an informal rule of biological evolution important to the understanding of the human condition: if an organic sensor can be imagined that picks up any signal from the environment, there exists a species somewhere that possesses it. The bountiful powers of life expressed in such diversity raise a question about the incapacity of the unaided human senses. Why can’t our species, the supposed summum bonum of Creation, do as much as all the animals combined, and more? Why were we brought into the world physically handicapped?
Evolutionary biology offers a simple answer. Natural selection……prepares organisms only for necessities…..It follows that each species lives in its own sensory world.…….Natural selection, in short, does not anticipate future needs. But this principle, while explaining so much so well, presents a difficulty. If the principle is universally true, how did natural selection prepare the mind for civilization before civilization existed? That is the great mystery of human evolution: how to account for calculus and Mozart.
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