Mathematics alone cannot tell us what specifically is out there in our universe. The mathematics can speculate only about what is possible. And sometiMathematics alone cannot tell us what specifically is out there in our universe. The mathematics can speculate only about what is possible. And sometimes mathematics allows us to explore pure potential before any physical manifestations of that potential are discovered. Black holes were like that, a purely mathematical construct on the page, benign in virtual form, in typescript on paper, unverified for decades, unaccepted for decades, absurd, maligned and denied by some great geniuses of the twentieth century, until physical evidence of real black holes in the galaxy was discovered.
Black holes are a gift, both physically and theoretically. They are detectable on the farthest reaches of the observable universe. They anchor galaxies, providing a center for our own galactic pinwheel and possibly every other island of stars. And theoretically, they provide a laboratory for the exploration of the farthest reaches of the mind. Black holes are the ideal fantasy scape on which to play out thought experiments that target the core truths about the cosmos.
“Black holes have no hair,” as John Wheeler quipped. If you could deduce any other features of the interior, any features other than mass, charge, and spin, it would be as though lines of information were emanating from the black hole, as though the black hole had hair. But the event horizon forbids the flow of information outward and therefore forbids the black hole from acquiring hair. “Black holes have no hair,” at least not for long. Any hair you try to give them will either fall in or be radiated away, restoring the hole to a pristine form. And so the black hole will remain featureless and without defect....more
Historically, the consensus has been that language evolved to allow humans to exchange factual information about the physical world, but an alternativHistorically, the consensus has been that language evolved to allow humans to exchange factual information about the physical world, but an alternative view is that language evolved, in modern humans at least, to facilitate social bonding.
Language has the obvious advantage that shifting some aspects of social bonding from a physical channel (grooming) to a vocal channel may allow several individuals to be ‘groomed’ simultaneously, allowing us to build a larger community. Language might do this in three quite different ways. One is by telling each other how we see the world (creating a common worldview); a second is through story-telling (stories about who we are and where we have come from); and the third is through making people laugh by telling jokes.
Telling a story – whether about what happened in history, or about the ancestors or who we are and where we came from, or about the people that live beyond the horizon, or the inhabitants of a spirit world that none of us can experience directly – creates a sense of community by binding us into a network of people who share a common view of the world....more
A simple short graphic description of Einstein's revolutionary theory of relativity. It was ok, but not at all comprehensive. So it doesn't cover everA simple short graphic description of Einstein's revolutionary theory of relativity. It was ok, but not at all comprehensive. So it doesn't cover everything, but it's a good introduction for those with no background in physics and cosmology....more
Figures such as Galileo, Newton, and Einstein are celebrated for proposing laws of physics that hadn’t previously been appreciated. But their accompliFigures such as Galileo, Newton, and Einstein are celebrated for proposing laws of physics that hadn’t previously been appreciated. But their accomplishments also share a common theme: They illuminate the universality of Nature. What happens here happens everywhere. Galileo showed that the heavens were messy and ever changing, just like conditions here on Earth; Newton understood that the same laws of gravity that accounted for falling apples could explain the motions of the planets; and Einstein realized that space and time were different aspects of a single unified spacetime, and that the curvature of spacetime underlies the dynamics of the Solar System and the birth of the universe. Likewise, the rules governing entropy and time are common to our everyday lives and to the farthest stretches of the multiverse. We don’t yet know all the answers, but we’re on the threshold of making progress on some big questions.
Over the course of this book, Sean Carroll investigates what we know about how time works, both in the smooth deterministic context of relativity and spacetime, and in the messy probabilistic world of statistical mechanics. He finally arrives at cosmology, and explores how our best theories of the universe fall embarrassingly short when confronted with the universe’s most obvious feature: the difference in entropy between early times and late times.
Understanding a deeply puzzling feature of the natural world is a process that can go through many stages—we may be utterly clueless, we may understand how to state the problem but not have any good ideas about the answer, we may have several reasonable answers at our disposal but not know which (if any) are right, or we may have it all figured out. The arrow of time falls in between the second and third of these options—we can state the problem very clearly but have only a few vague ideas of what the answer might be.
In such a situation, it’s appropriate to dwell on understanding the problem, and not become too wedded to any of the prospective solutions. A century from now, most everything Carroll covers in the first three parts of this book should remain standing. Relativity is on firm ground, as is quantum mechanics, and the framework of statistical mechanics. We are even confident in our understanding of the basic evolution of the universe, at least from a minute or so after the Big Bang up to today. But our current ideas about quantum gravity, the multiverse, and what happened at the Big Bang are still very speculative. They may grow into a robust understanding, but many of them may be completely abandoned. At this point it’s more important to understand the map of the territory than to squabble over what is the best route to take through it....more
In physics and cosmology we always like to know about the origins. How did the universe begin? What forces were at play? How were atoms and chemical eIn physics and cosmology we always like to know about the origins. How did the universe begin? What forces were at play? How were atoms and chemical elements created? How did stars, planets and galaxies form?
What we rarely speak about though is how the universe will end. I think it's high time we did more theorizing and postulating on Doomsday scenarios (i.e how the universe will end). And this book does just that. I believe there aren't many books like this around. The subject is unfortunately ignored by most researchers. Kate Mack does a fabulous job of explaining how our current understanding of cosmology and particle physics can help us to determine what fate awaits our universe. Understanding the cosmological constant and dark energy plays a crucial part here. If W (the ratio of pressure that dark energy puts on the universe) equals minus one (W = -1), then the universe will keep on expanding forever, in which case we'll be left with a universe filled with radiation and nothing interesting happening. The stars will eventually stop shining and new ones won't be born. Even the black holes which seemed eternal at one point, are doomed to evaporate in the end due to Hawking radiation (this will occur trillions of years in the future, by the way). This is called the heat death of the universe. If,by any chance, W is anything other than minus one, (W<-1 or W>-1), then the universe will go through either a big crunch (it collapses on itself) or a big rip (the expansion acceleration gets so fast that the fabric of space itself is ripped to shreds). It is also possible that our universe is in a cyclical state, in which case many big bangs have occurred and will occur recycling the contents of our universe....more
This is an excellent book full of inspiring ideas. Jim Al- Khalili is a physicist and a wonderful science popularizer. I'd read a few books written byThis is an excellent book full of inspiring ideas. Jim Al- Khalili is a physicist and a wonderful science popularizer. I'd read a few books written by him already. He tends to explain complex concepts in science in a very lucid and accessible way.
This book is all about physics; why it matters and how it was developed. The first chapter is about the awe of understanding. Why do we have this burning curiosity to learn how things work? Why did we create myths in the beginning? How did science replace these myths? Through rational analysis and careful observation—a painstaking process of testing and building up scientific evidence, rather than accepting stories and explanations with blind faith—we can now claim with a high degree of confidence that we know quite a lot about our universe. We can also now say with confidence that what mysteries remain need not be attributed to the supernatural. They are phenomena we have yet to understand—and which we hopefully will understand one day through reason, rational enquiry, and, yes … physics.
The second chapter is about scales. The world of physics only really came of age in the seventeenth century, thanks to a large extent to the invention of the two most important instruments in all of science: the telescope and the microscope. If we were only able to understand the world we can see with our naked eyes, then physics would not have got very far. once the microscope and the telescope were invented, they opened up windows on the world that dramatically increased our understanding, magnifying the very small and bringing closer the very far away.
Chapter three covers the enigma of space and time. Space and time are the substrates in which all events take place. However, such concepts are slippery. Common sense tells us that space and time should be in place from the start—that space is where events happen and the laws of physics are acted out, while the inexorable passage of time is, well, just is. But, is our commonsense view of space and time right? An important lesson physicists must learn is to not always trust common sense. After all, common sense tells us that the Earth is flat, but even the Ancient Greeks understood that its sheer size meant we could not easily discern its curvature, but that there were simple experiments they could perform to prove that it was in fact a sphere. Similarly, everyday experience tells us that light has the properties of a wave and therefore cannot also behave as though it were made up of a stream of individual particles.
some of the most important breakthroughs in physics have been the results of the logical conclusions drawn not from real experiments or observations, but from ‘thought experiments’, whereby the physicist considers some hypothesis and devises an imaginary experiment that can test its consequences. Some of the most famous thought experiments were conducted by Einstein and helped him develop his theories of relativity. Once his theories were fully developed of course they could be tested in real laboratory experiments.
Chapter four deals with energy and matter. In physics, the concept of energy indicates the capacity to do work; thus, the more energy something has, the more it is able to do, whether that ‘doing’ means moving matter from one place to another, heating it up, or just storing the energy for later use. The law of conservation of energy states that the total amount of energy in the universe is constant. The conservation of energy also tells us that perpetual motion machines are impossible, since energy cannot be continually conjured up from nowhere. In everyday language, mass is often taken to mean the same thing as weight. This is fine on Earth since the two quantities are proportional to each other: if you double a body’s mass you will also double its weight. But out in empty space, a body has no weight, even though its mass stays the same.
In chapter five we enter the weird world of quantum mechanics. An electron is in a superposition. It has a wave function. Based on Heisenberg's uncertainty principle, we cannot measure the velocity and position of a particle at the same time.
Chapter six is about thermodynamics and the arrow of time. when the system reaches equilibrium, its entropy is maximised, and the energy it contains is useless. So, in a sense, it is not energy that is needed to make the world go around, it is low entropy. If everything were in a state of equilibrium, nothing would happen. We need a system to be in a state of low entropy, far from equilibrium, to force energy to change from one form to another—in other words, to do work. Life is an example of a system that can maintain itself in a state of low entropy.
In chapter seven, the author tries to explain the roads to unification. And basically why physicists have this urge to unify different concepts in physics.
Chapter eight is about some of the problems physicists are dealing with and why nothing interesting has happened for a while in physics. We haven't been surprised for a long time. We haven't had revolutionary discoveries like that or Einstein.
Chapter nine is about the usefulness of physics. GPS systems are now such an integral part of our lives that we could not live without them. Not only do we take for granted the fact that we no longer get lost in unfamiliar parts of the world, but GPS has allowed us to see our planet from above and map it with remarkable detail, enabling us to study the way the Earth’s climate is changing, or to predict natural phenomena and help with disaster relief. an understanding of the quantum rules that explain how electrons behave in semiconductor materials like silicon has laid the foundation of our technological world. Without an understanding of semiconductors, we would not have developed the transistor and, later, the microchip and the computer.
And finally, chapter ten teaches you how to think like a physicist. Unlike politicians, physicists have no fear of admitting that they're wrong. Being wrong means there are more interesting things waiting to be discovered. People are often shocked to hear that many physicists—other than those who had dedicated years of their lives to building the Large Hadron Collider—were hoping that the Higgs boson would not be found. You see, not finding the Higgs would have meant that there really was something wrong with the Standard Model, opening the door to exciting new physics. Merely ticking a box to confirm something we already suspect to be true is just not as exciting as finding out that one needs to pursue hitherto unexplored paths of research....more
This is a book about philosophy of science. But why do we need to study philosophy of science? Many important question about a discipline, such as natThis is a book about philosophy of science. But why do we need to study philosophy of science? Many important question about a discipline, such as nature of its concepts and its relation to other disciplines, are philosophical in nature. Philosophy of science, for example, is needed to supplement the understanding of the natural and social sciences that derives from scientific work itself. Philosophy studies every subject matter that the sciences also study, but it does this with different aims and methods. Philosophy can also turn us into good critical thinkers....more
This is a book that tries to describe the weirdness of quantum mechanics. And I think it does a great job. Although it is written primarily for the geThis is a book that tries to describe the weirdness of quantum mechanics. And I think it does a great job. Although it is written primarily for the general audience, I don't recommend it if you're not familiar with the ABC of QM. There are much simpler books out there.
Quantum mechanics doesn’t tell us how a thing is, but what (with calculable probability) it could be, along with – and this is crucial – a logic of the relationships between those ‘coulds’. If this, then that. What this means is that, to truly describe the features of quantum mechanics, as far as that is currently possible, we should replace all the conventional ‘isms’ with ‘ifms’. For example:
Not ‘here it is a particle, there it is a wave’
but ‘if we measure things like this, the quantum object behaves in a manner we associate with particles; but if we measure it like that, it behaves as if it’s a wave’
Not ‘the particle is in two states at once’
but ‘if we measure it, we will detect this state with probability X, and that state with probability Y’...more
This is one of the best popular science books that I have read in a while. Brian Greene takes you to a fascinating journey which involves not only cosThis is one of the best popular science books that I have read in a while. Brian Greene takes you to a fascinating journey which involves not only cosmology and particle physics, but also deeper questions like the meaning of life or why religion has lasted so long despite its irrational ideas. In one chapter he deals with the second law of thermodynamics and entropy. The way he illuminated the ideas behind the second law was so lucid. And even though I already knew briefly as a non-expert what the law meant, I still learned so much and now I got new perspectives on it. He gives a brief account of the steam engine and how it inspired scientists to try come up with ways to reduce energy waste. The result of many years of arduous studies and grueling tests was the second law. Then we go to the origin of the universe and how space was inflated by repulsive gravity and how inflationary cosmology describes the emergence of order in patches of space in otherwise chaotic disordered universe. When inflationary expansion rapidly stretches minute quantum energy variations, they spread across space making the temperature a touch hotter over here and a touch cooler over there. The result was the creation of matter, the stars, planets and entire galaxies that we observe. Then he takes a turn to describe the evolution of life on our planet and explains why life on Earth does not defy the second law. He praises Shrodinger's book on life which I have not read. Schrödinger’s goal was not to reveal life hovering within a single atom but to build upon the understanding of atoms to construct a physicist’s explanation of how a large collection might assemble into something that lives. The next stop was the hard problem of consciousness. The fact that we know almost nothing about consciousness is staggering. That being said, new discoveries in neuroscience has shed some light on the brain function and how consciousness is actually associated with the activity of some parts. However, the large picture is still fuzzy. He talks a bit about language and how without language our capacity for certain kinds of mental maneuvers would diminish. Words not only express reasoning, they vitalize it. Darwin speculated that language emerged from song and imagined that those endowed with Elvis-like talents would more readily attract mates and thus more abundantly seed subsequent generations of gifted crooners. Given enough time, their melodious sounds would gradually transform into words. Alfred Russel Wallace, Darwin’s lesser-feted codiscoverer of evolution by natural selection, saw things differently. He was convinced that natural selection could not shed light on the human capacities for music, art, and, in particular, language. When Darwin read Wallace’s article, he was aghast, responding with a heavily emphasized “no” noting to Wallace: “I hope you have not murdered too completely your own & my child. Why do we have language? Did evolution directly select for language because it provides a survival advantage, or is language a by-product of other evolutionary developments like larger brain size? Noam Chomsky, among the most influential of all modern linguists, has argued that the human capacity to acquire language relies on us each possessing a hardwired universal grammar. universal grammar proposes that there is something in our innate neurobiological makeup that provides a language primer, a species-wide brain boost that propels us all to listen, to understand, and to speak. Cognitive psychologists Steven Pinker and Paul Bloom, pioneers of a Darwinian approach to language, suggest a less bespoke history, one in which language emerged and developed through the familiar pattern of a gradual buildup of incremental changes that each conferred a degree of survival advantage. Then we move to religion. We can trace our ancestors' beliefs in archeological sites. Caves were far from just ‘canvases.’ They were places in which rituals were conducted, where people communicated with spirits and ancestors dwelling in another realm, they were places loaded with meaning and resonance. This reciprocal variety of altruism may be the source of the transactional nature of the relationship adherents typically have with the supernatural beings that populate religious traditions: I’ll sacrifice, I’ll pray, I’ll do good, but come tomorrow’s combat, you’ve got my back. Religion is story, enhanced by doctrines, rituals, customs, symbols, art, and behavioral standards. By conferring an aura of the sacred upon collections of such activities and by establishing an emotional allegiance among those who practice them, religion extends the club of kinship. Religion provides membership to unrelated individuals who thus feel part of a strongly bound group. Then we have Doomsday scenarios on how the world will actually end. Will it end in a big rip where the acceleration of the universe is so fast that even the atoms on your body will disintegrate? There's so much more insight you can get from this book. If you're a science enthusiast like I am, I highly recommend it. Do yourself a favor and read this book. It will open your mind....more
This is a book about how Darwin's theory of evolution affects our view of religion and God, meaning of life and morality.
Evolutionary theory answers This is a book about how Darwin's theory of evolution affects our view of religion and God, meaning of life and morality.
Evolutionary theory answers one of the most profound and fundamental questions human beings have ever asked themselves, a question that has plagued reflective minds for as long as reflective minds have existed in the universe: why are we here? The answer is simple: we are here because we have evolved from other species.
The concept of God has been among the most influential concepts in the history of the human species. The problem is, though, that trying to pin down a definition of God is a little like trying to nail jelly to a tree.
how did we and the other animals come to exist? In the early twenty-first century, there is really only one scientific answer to this question: we evolved. In popular culture, though, there is another contender. This is the position known as creationism. Creationists reject evolutionary theory as a huge mistake or even a Great Lie, invented (perhaps by the Devil) to lure people away from God and spread atheism.
Part of the book tries to establish the fact that Evolution really happened. Some evidence is provided: Fossil record, DNA, vestigial organs, etc.
The image-of-God thesis is the idea that we and we alone were created in the image of God and have an immortal soul, and that this is a fundamental difference between all humans and all other animals that justifies a fundamental difference in how we treat all humans v. all other animals. The rationality thesis is the idea that we and we alone possess rationality – the spark of reason – and that this is the difference that justifies privileging members of our species above all others. Evolutionary theory undermines both these theses.
Reciprocal altruism theory highlights the fact that, if you give to others even if they do not give to you, you’re liable to be exploited. Assuming you don’t want to be exploited, you might decide to reject moral precepts such as ‘turn the other cheek’ and ‘resist not evil’, and instead deny help to those who don’t reciprocate.
In the end, our decisions on whether something is right or wrong should be based on an assessment of real risks and benefits, not on half-baked ideas about naturalness v. unnaturalness. So our moral precepts are based on reasoned arguments and there's probably no objective morality decreed by some god or supernatural deity....more
Our universe began some 14 billion years ago when matter, energy, time, and space burst forth.
And the darkness was cold, and the light was hot, and thOur universe began some 14 billion years ago when matter, energy, time, and space burst forth.
And the darkness was cold, and the light was hot, and the union of these extremes gave shape to matter and there was structure. And there were great stars hundreds of times the mass of our sun. And these stars exploded, sending oxygen and carbon to the worlds to come and adorning them with gold and silver. And in their deaths, the stars became darkness and the weight of their darkness anchored the light. And new stars were born from their death shrouds. And they began to dance with each other and now there were galaxies.
And the galaxies made stars. And the stars made worlds. And on at least one of those worlds there came a time when heat shot out from its molten heart, and it warmed the waters. And the matter that had rained down from the stars came alive and that starstuff became aware.
And that life was sculpted by the earth, and its struggles with the other living things. And a great tree grew up, one with many branches, and six times it was almost felled. But still it grows and we are but one small branch, one that cannot live without its tree.
And slowly, we learned to read the book of nature, to learn its laws, to nurture the tree. To find out where and when we are in the great ocean, to become a way for the cosmos to know itself and to return to the stars....more
Exploring planets is more than just a leisure activity. We do it for fun, but we also do it to learn more about our own planet and ultimately our own Exploring planets is more than just a leisure activity. We do it for fun, but we also do it to learn more about our own planet and ultimately our own existence. This book was a joyful experience. It took me back to four and a half billion years ago....more
Another great book on critical thinking. In order to best express ourselves, we need to know how to think clearly and systematically — meaning practicAnother great book on critical thinking. In order to best express ourselves, we need to know how to think clearly and systematically — meaning practice critical thinking. Critical thinking also means knowing how to break down texts, and in turn, improve our ability to comprehend. In learning how to analyse the logical structure of texts, critical thinking improves comprehension abilities. Without critical thinking, how can we really live a meaningful life?
We need this skill to self-reflect and justify our ways of life and opinions. Critical thinking provides us with the tools to evaluate ourselves in the way that we need to.
Critical thinking is crucial for many career paths. Not just for scientists, but lawyers, doctors, reporters, engineers, accountants, and analysts (among many others) all have to use critical thinking in their positions.
Those with critical thinking skills tend to solve problems as part of their natural instinct. Critical thinkers are patient and committed to solving the problem, similar to Albert Einstein, one of the best critical thinking examples, who said “It’s not that I’m so smart; it’s just that I stay with problems longer.”...more
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