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The Cosmic Web: Mysterious Architecture of the Universe
J. Richard Gott was among the first cosmologists to propose that the structure of our universe is like a sponge made up of clusters of galaxies intricately connected by filaments of galaxies—a magnificent structure now called the "cosmic web" and mapped extensively by teams of astronomers. Here is his gripping insider's account of how a generation of undaunted theorists and observers solved the mystery of the architecture of our cosmos.
The Cosmic Web begins with modern pioneers of extragalactic astronomy, such as Edwin Hubble and Fritz Zwicky. It goes on to describe how, during the Cold War, the American school of cosmology favored a model of the universe where galaxies resided in isolated clusters, whereas the Soviet school favored a honeycomb pattern of galaxies punctuated by giant, isolated voids. Gott tells the stories of how his own path to a solution began with a high-school science project when he was eighteen, and how he and astronomer Mario Jurič measured the Sloan Great Wall of Galaxies, a filament of galaxies that, at 1.37 billion light-years in length, is one of the largest structures in the universe.
Drawing on Gott’s own experiences working at the frontiers of science with many of today’s leading cosmologists, The Cosmic Web shows how ambitious telescope surveys such as the Sloan Digital Sky Survey are transforming our understanding of the cosmos, and how the cosmic web holds vital clues to the origins of the universe and the next trillion years that lie ahead.
The Cosmic Web begins with modern pioneers of extragalactic astronomy, such as Edwin Hubble and Fritz Zwicky. It goes on to describe how, during the Cold War, the American school of cosmology favored a model of the universe where galaxies resided in isolated clusters, whereas the Soviet school favored a honeycomb pattern of galaxies punctuated by giant, isolated voids. Gott tells the stories of how his own path to a solution began with a high-school science project when he was eighteen, and how he and astronomer Mario Jurič measured the Sloan Great Wall of Galaxies, a filament of galaxies that, at 1.37 billion light-years in length, is one of the largest structures in the universe.
Drawing on Gott’s own experiences working at the frontiers of science with many of today’s leading cosmologists, The Cosmic Web shows how ambitious telescope surveys such as the Sloan Digital Sky Survey are transforming our understanding of the cosmos, and how the cosmic web holds vital clues to the origins of the universe and the next trillion years that lie ahead.
296 pages, Hardcover
First published February 9, 2016
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1097 people want to read
About the author
J. Richard Gott III
8 books55 followersJohn Richard Gott III is a professor of astrophysical sciences at Princeton University. He is known for developing and advocating two cosmological theories with the flavour of science fiction: Time travel and the Doomsday argument.
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Displaying 1 - 30 of 34 reviews
March 13, 2016
The world we live in keeps getting bigger. Quite a long time ago, some smart people in Greece figured out roughly what the Earth looks like:
Admittedly they got a few details wrong, but that was eventually sorted out. Then, a bit less than two thousand years later, other people realized that the Earth was just one of a bunch of planets, that together with the sun made up our solar system:
Again, a few details needed to be corrected - it took a while to discover that there were rings around one of the planets, there were more planets than the six that had first been spotted, and there were all these weird little rocks between the fourth and fifth planets.
About a hundred years ago, our world once again expanded. The people who worked out what our solar system looked like had also concluded that the stars must be other suns, and that the vague glow that spread in a band across the sky was really a bunch of distant stars; evidently we lived in the middle of a huge cloud of them. Now, with better telescopes, it became clear that other vague glowing patches were similar clouds of stars, seen from a great distance. At least as far back as Kant's forgotten astronomy book, the Universal Natural History, there had been scientists and philosophers prepared to argue for this controversial idea. By now, we've all seen pictures of galaxies:
In 2016, everybody knows that we live on a planet, which is in a solar system, which is in a galaxy. So where is our galaxy? It's common knowledge that there are zillions of them dotting the space around the one we happen to live in. But what does geography look like on the intergalactic scale? That's sort of the central question Richard Gott's book is exploring, and I was embarrassed to find that I didn't know. It wasn't like I was completely ignorant. I was aware that our galaxy was part of a collection imaginatively called "The Local Group". And I'd read that galaxies often congregated in "sheets" or "filaments". All the same, what was the next picture in the sequence?
Well, having finished the book, I'm better informed, and there turns out to be a satisfyingly elegant answer. It's easy to get confused, since you need to be careful about just which question you're asking. A straightforward way of looking at it is to draw a three-dimensional map of the space around us, which is something like this:
But the random-looking collection of blobs above misses the essential point. What the map shows us is the parts of space where there's a lot of stuff. Well, of course, you may protest: what else would it show? From our very small-scale point of view, it seems like the only possible way to think. Our solar system is mostly empty space, with some planets floating in it. Our galaxy is even emptier space, with some stars, gas and black holes floating in it. A map ought to show where those things are. Right?
In fact, wrong! When we think about the whole universe, we shouldn't be thinking of it as mostly empty space with some objects scattered around here and there. One of the key discoveries that astronomers have made over the last twenty years is that the expanding universe created by the Big Bang is "flat"; it's exactly balanced on the knife-edge between a positively curved space, where gravity is stronger than expansion, and a negatively curved space, where expansion is stronger than gravity. This may sound boring and abstract, but in fact it leads to some very concrete consequences. Since the whole universe is poised on this knife-edge between expansion and gravity, it follows that each part of it was originally also close to being on the same knife-edge. The key word is "close". Some parts of the universe were very slightly denser than average, and gravity won to make them start contracting; other parts were very slightly less dense than average, and expansion won to make them start thinning out.
When astronomers began to study the geography of the universe, they noticed huge clumps of matter, like the ones in the picture above; they also noticed huge "voids", virtually empty spaces where there were next to no galaxies. At first, there was disagreement between the people who thought the clumps were the important thing (the "meatball soup model") and the people who thought the voids were the important thing (the "Swiss cheese model"). In fact, the flatness of the universe makes the situation symmetrical. If you draw maps of high-density regions - the "meatballs" - they are almost exactly the same as maps of low-density regions - the holes in the "Swiss cheese". When you plot the 50% contour, you find the low-density part of the universe has just the same kind of twisty three-dimensional shape as the high-density part. They both look like marine sponges, full of holes and passageways, and they interpenetrate each other in many places. A 50% contour map looks like the one below, where you can see that the solid part and the empty part each fill up roughly the same volume.
I'm afraid I've only given the merest sketch, and when you follow up the details you find the story spreads out in all kinds of fascinating directions. The crucial importance of dark matter and dark energy; how "inflation" during the first fraction of a second may have created the little density imbalances; the way gravitational lenses provide the data for cosmic cartographers; using topology to talk quantitatively about the shapes that arise. If I've managed to get you hooked, buy Richard Gott's book and find out more for yourself. I'm not exaggerating when I say it'll change your picture of the whole universe.
Admittedly they got a few details wrong, but that was eventually sorted out. Then, a bit less than two thousand years later, other people realized that the Earth was just one of a bunch of planets, that together with the sun made up our solar system:
Again, a few details needed to be corrected - it took a while to discover that there were rings around one of the planets, there were more planets than the six that had first been spotted, and there were all these weird little rocks between the fourth and fifth planets.
About a hundred years ago, our world once again expanded. The people who worked out what our solar system looked like had also concluded that the stars must be other suns, and that the vague glow that spread in a band across the sky was really a bunch of distant stars; evidently we lived in the middle of a huge cloud of them. Now, with better telescopes, it became clear that other vague glowing patches were similar clouds of stars, seen from a great distance. At least as far back as Kant's forgotten astronomy book, the Universal Natural History, there had been scientists and philosophers prepared to argue for this controversial idea. By now, we've all seen pictures of galaxies:
In 2016, everybody knows that we live on a planet, which is in a solar system, which is in a galaxy. So where is our galaxy? It's common knowledge that there are zillions of them dotting the space around the one we happen to live in. But what does geography look like on the intergalactic scale? That's sort of the central question Richard Gott's book is exploring, and I was embarrassed to find that I didn't know. It wasn't like I was completely ignorant. I was aware that our galaxy was part of a collection imaginatively called "The Local Group". And I'd read that galaxies often congregated in "sheets" or "filaments". All the same, what was the next picture in the sequence?
Well, having finished the book, I'm better informed, and there turns out to be a satisfyingly elegant answer. It's easy to get confused, since you need to be careful about just which question you're asking. A straightforward way of looking at it is to draw a three-dimensional map of the space around us, which is something like this:
But the random-looking collection of blobs above misses the essential point. What the map shows us is the parts of space where there's a lot of stuff. Well, of course, you may protest: what else would it show? From our very small-scale point of view, it seems like the only possible way to think. Our solar system is mostly empty space, with some planets floating in it. Our galaxy is even emptier space, with some stars, gas and black holes floating in it. A map ought to show where those things are. Right?
In fact, wrong! When we think about the whole universe, we shouldn't be thinking of it as mostly empty space with some objects scattered around here and there. One of the key discoveries that astronomers have made over the last twenty years is that the expanding universe created by the Big Bang is "flat"; it's exactly balanced on the knife-edge between a positively curved space, where gravity is stronger than expansion, and a negatively curved space, where expansion is stronger than gravity. This may sound boring and abstract, but in fact it leads to some very concrete consequences. Since the whole universe is poised on this knife-edge between expansion and gravity, it follows that each part of it was originally also close to being on the same knife-edge. The key word is "close". Some parts of the universe were very slightly denser than average, and gravity won to make them start contracting; other parts were very slightly less dense than average, and expansion won to make them start thinning out.
When astronomers began to study the geography of the universe, they noticed huge clumps of matter, like the ones in the picture above; they also noticed huge "voids", virtually empty spaces where there were next to no galaxies. At first, there was disagreement between the people who thought the clumps were the important thing (the "meatball soup model") and the people who thought the voids were the important thing (the "Swiss cheese model"). In fact, the flatness of the universe makes the situation symmetrical. If you draw maps of high-density regions - the "meatballs" - they are almost exactly the same as maps of low-density regions - the holes in the "Swiss cheese". When you plot the 50% contour, you find the low-density part of the universe has just the same kind of twisty three-dimensional shape as the high-density part. They both look like marine sponges, full of holes and passageways, and they interpenetrate each other in many places. A 50% contour map looks like the one below, where you can see that the solid part and the empty part each fill up roughly the same volume.
I'm afraid I've only given the merest sketch, and when you follow up the details you find the story spreads out in all kinds of fascinating directions. The crucial importance of dark matter and dark energy; how "inflation" during the first fraction of a second may have created the little density imbalances; the way gravitational lenses provide the data for cosmic cartographers; using topology to talk quantitatively about the shapes that arise. If I've managed to get you hooked, buy Richard Gott's book and find out more for yourself. I'm not exaggerating when I say it'll change your picture of the whole universe.
February 6, 2016
Extremely dense and detailed writing but ultimately worth it, so in other words - not quite on the level of traditional, "science for the layman," style books; definitely intended for a more specific audience but the work presented here is astonishing and ultimately illuminating. A fascinating glimpse into the process by which the large structure of our universe has been calculated and observed.
August 24, 2020
When you are reading a big picture science book, it’s usually pretty easy to tell whether you are reading something written by a scientist or by a science writer. This one is written by a scientist.
J. Richard Gott gives a first-hand, participant account of the current state of the investigation of the large scale structure of the universe.
Gott is a very gifted topologist, as his high school science fair project on spongelike pseudopolyhedrons evidences. He later came back to those shapes as models for thinking about the shape of the universe.
He begins the book with some history — the debates that established some of the givens of the current debate, that we live in a spiral arm of one galaxy, in a universe of many, many galaxies, in a space that is expanding in every direction, from an initial Big Bang.
The question that Gott focuses on is what the topology of the largest structures in the universe is and how it got there. There are two main theories leading up to Gott’s own contributions.
One is a “meatball” structure, championed by James Peebles and others. In this picture, galaxies form first, then cluster into larger structures, with voids between them. The universe is composed of these gravitationally-grown clusters and super-clusters surrounded by a sea of sparsely populated voids.
The opposing view was championed by the Soviet Yakov Zeldovich. In Zeldovich’s picture, the voids formed first, expanding and pushing the masses that became the galaxies into thin pancake structures. The shape is analogous to swiss cheese, with large bubble-like voids among the dense masses of galaxies, clusters, and super-clusters.
Gott’s own picture is informed by contemporary studies of how random quantum fluctuations influenced the initial expansion of the universe. Those very small fluctuations grow gravitationally via dark matter density into large-scale mass filaments, evolving into the galaxies and clusters of galaxies observable today. The structure that Gott finds is “sponge-like”, with, unlike either the meatball or swiss cheese shapes, a symmetry between dense and sparse regions.
The sparse and dense regions together form a whole in which each comprises a continuous connected structure. You can travel, in principle, through all of the voids on a continuous path, or through all of the complementary dense regions, also on a continuous path. The two types of regions complement one another in complex but continuous mirrors of one another.
The story of course is much more complicated, and Gott takes us through some of the details. As a scientist, Gott excels at explanation at a relatively non-technical level. But I did find the levels at which he explains his topics to be uneven —on one hand explaining more than once why galaxies of the same size look differently sized depending on their distance, and on the other going pretty quickly through the explanation of exotic topologies like pseudopolyhedrons.
The final Chapter 11 extrapolates discoveries about the composition and dynamics of our universe into far distant future scenarios about the universe’s fate. Those scenarios include relatively mundane ideas about the birth of bubble universes and more bizarre ideas such as Boltzmann Brains. It gets a bit speculative, but in a good way.
This isn’t that easy a book, but if you want to see the development of current thinking about the shape of the universe from the vantage point of a participant, this is a great place to go. It can be challenging. It was to me, as neither a physicist nor a mathematician, but with some background in astronomy and cosmology. There are books more fitted to a general audience — this one fills a different niche.
J. Richard Gott gives a first-hand, participant account of the current state of the investigation of the large scale structure of the universe.
Gott is a very gifted topologist, as his high school science fair project on spongelike pseudopolyhedrons evidences. He later came back to those shapes as models for thinking about the shape of the universe.
He begins the book with some history — the debates that established some of the givens of the current debate, that we live in a spiral arm of one galaxy, in a universe of many, many galaxies, in a space that is expanding in every direction, from an initial Big Bang.
The question that Gott focuses on is what the topology of the largest structures in the universe is and how it got there. There are two main theories leading up to Gott’s own contributions.
One is a “meatball” structure, championed by James Peebles and others. In this picture, galaxies form first, then cluster into larger structures, with voids between them. The universe is composed of these gravitationally-grown clusters and super-clusters surrounded by a sea of sparsely populated voids.
The opposing view was championed by the Soviet Yakov Zeldovich. In Zeldovich’s picture, the voids formed first, expanding and pushing the masses that became the galaxies into thin pancake structures. The shape is analogous to swiss cheese, with large bubble-like voids among the dense masses of galaxies, clusters, and super-clusters.
Gott’s own picture is informed by contemporary studies of how random quantum fluctuations influenced the initial expansion of the universe. Those very small fluctuations grow gravitationally via dark matter density into large-scale mass filaments, evolving into the galaxies and clusters of galaxies observable today. The structure that Gott finds is “sponge-like”, with, unlike either the meatball or swiss cheese shapes, a symmetry between dense and sparse regions.
The sparse and dense regions together form a whole in which each comprises a continuous connected structure. You can travel, in principle, through all of the voids on a continuous path, or through all of the complementary dense regions, also on a continuous path. The two types of regions complement one another in complex but continuous mirrors of one another.
The story of course is much more complicated, and Gott takes us through some of the details. As a scientist, Gott excels at explanation at a relatively non-technical level. But I did find the levels at which he explains his topics to be uneven —on one hand explaining more than once why galaxies of the same size look differently sized depending on their distance, and on the other going pretty quickly through the explanation of exotic topologies like pseudopolyhedrons.
The final Chapter 11 extrapolates discoveries about the composition and dynamics of our universe into far distant future scenarios about the universe’s fate. Those scenarios include relatively mundane ideas about the birth of bubble universes and more bizarre ideas such as Boltzmann Brains. It gets a bit speculative, but in a good way.
This isn’t that easy a book, but if you want to see the development of current thinking about the shape of the universe from the vantage point of a participant, this is a great place to go. It can be challenging. It was to me, as neither a physicist nor a mathematician, but with some background in astronomy and cosmology. There are books more fitted to a general audience — this one fills a different niche.
March 19, 2021
Quite dense; not an easy read for non-scientists like myself. But, it was a fun challenge. It answered a lot of the questions I had ("how could they know that?...") when it comes to the age and nature of the universe. The book is laid out showing the history of the ways scientists have modeled the structure of the universe over the past 100 years. It ends with the latest ideas, and the questions being worked on right now.
August 24, 2020
first-rate. This seems more like a compilation of research papers than a popular science book. It showed how the view about the large-scale structure of the universe evolves, from the competing theories of Dr. Jim Peebles' "meatballs" model to Dr. Zeldovich's "pancake" model, to widespread acceptance of Dr. Guth's inflation theory and implications for a multiverse, to the author (Princeton professor Dr. Gott's) theory of a spongelike universe.
July 7, 2016
A look into how the large-scale structure of the universe was discovered, that gives attention to both the US and Soviet schools, brings out their differences clearly and continues beyond to 21st century.
The book does go more deeply into Gott's own part in it, but as a major contributor to the field, it's fine.
There were some detours that led a bit further away from cosmology (and were a great part to read), so you do come across two different styles of writing - one's more conversational and the other more precise and scientific and peppered with figures, symbols and graphs - the latter is great because you do get the details, and the former lets you take a deep breath before diving back into the depths of deep space.
It's not a difficult read as such, but I wouldn't recommend reading it as the first one about cosmology.
The book does go more deeply into Gott's own part in it, but as a major contributor to the field, it's fine.
There were some detours that led a bit further away from cosmology (and were a great part to read), so you do come across two different styles of writing - one's more conversational and the other more precise and scientific and peppered with figures, symbols and graphs - the latter is great because you do get the details, and the former lets you take a deep breath before diving back into the depths of deep space.
It's not a difficult read as such, but I wouldn't recommend reading it as the first one about cosmology.
September 12, 2019
A fascinating review of modern cosmology with great details on how we know what happened in the early universe. Most illuminating was a clear explanation of Inflation, including the part that many descriptions leave out and thus leave confusion - that space itself can expand faster than light, allowed in Einstein’s relativity theory. There’s a lot about topology, which the author began studying as a school kid and later found application to understanding large Galaxy surveys full of filaments and voids. Is the large scale structure like Swiss cheese or a meatball stew. I’ll let you read to find out. An excellent read, some parts technical which if you want to skip will not take away from the really clear explanations in the rest of the book.
February 28, 2021
Excerpts from this hard-to-understand for a layman but a beautiful book!
"Origin of the Name Cosmic Web
Where did the name cosmic web come from? The first paper to use it in either its title or abstract was the 1995 arXiv preprint posted online by Richard Bond, Lev Kofman, and Dmitry Pogosyan. The title of their paper was “How Filaments Are Woven into the Cosmic Web” (1995)."
"The largest structures in the universe are giant filaments of galaxies stretching between the great clusters—the greatly expanded fossil remnants of initial random quantum fluctuations. Grown by gravity with the help of the mysterious cold dark matter, they form a magnificent, spongelike cosmic web."
"
"By 1983 the overarching battle lines in cosmology were set. Would the American school led by Peebles triumph, or would Zeldovich win in the end? Would it be meatballs or honeycombs? A newly discovered theory for the origin of the universe—inflation—would provide a clue."
"Boltzmann Brains
Once in a great while—once in every 10∧10∧70 years—you will see something called a Boltzmann brain; that is, something as complicated as the human brain will appear at random from the thermal radiation. I have argued (Gott 2008) that although you may see such a brain in the distance if you wait long enough, it would not be a self-conscious intelligent observer—because the thermal radiation is observer dependent.
This becomes important if the universe expands forever; because even though Boltzmann brains would be seen infrequently, there would be an infinite number of them, in the infinite future, and the Boltzmann brains would far outnumber normal intelligent observers made of atoms circling normal stars. That would make us special, and that’s not allowed by the Copernican principle. One might ask, if Boltzmann brains outnumber normal observers by an infinite factor, then why am I not one of them? Such apparent contradictions lead some physicists to rule out an infinite future exponential expansion for our universe.
In this case, according to an argument by Freeman Dyson, intelligent life might continue on forever, in principle, by thinking ever more slowly, using less and less energy, and dumping waste heat into the ever-cooling cosmic microwave background. Intelligent life in the far future would have to become a thin cloud composed of electrons and positrons—the only ordinary matter particles left. These particles would have to produce large, complex structures without annihilating each other—difficult to accomplish in practice but possible in principle."
"Heat death for intelligent life
About 840 billion years from now, the cosmic microwave background photons become redshifted to a lower temperature than the Gibbons and Hawking radiation and become unimportant. The temperature of the universe bottoms out at 7 × 10−31 K, the Gibbons and Hawking temperature. That’s just above absolute zero on the Kelvin scale, about 4 × 1032 times colder than ice water. Still, this is a finite temperature, and as we shall see this has interesting consequences at late times. Eventually, one would come into thermal equilibrium with this thermal radiation, and there would be a heat death for intelligent life.
The stars will have all burnt out by about 10^14 years from now. Protons should decay into positrons and neutrinos, somewhere between 10^34 and 10^64 years from now. Then the heaviest particles left around will be electrons and positrons. They will be so spread out that they can’t find each other to annihilate. About 10^100 years from now, galactic-mass black holes will evaporate by Hawking radiation and blink out in a burst of glory.
Then it will be dark, with nothing to look at but the Gibbons and Hawking thermal radiation from the event horizons of the universe as a whole. It would be like watching static on your television. Now we need some even larger numbers to help us. The number 10^100 is called a googol. We can also write it as 10∧100. Now 10 raised to the googol power is 10∧10∧100 and we call that a googolplex. If you wait long enough, that random static you see in the Gibbons and Hawking radiation will eventually show something interesting (not that anyone would likely be around to observe it). (Remember the old story: if you have monkeys randomly typing and you wait long enough, one of them will eventually produce a copy of one of Shakespeare’s plays by chance.)"
"In this he anticipated quasars—bright galactic nuclei which were indeed mistaken at first for stars in our own galaxy. It was Maarten Schmidt, also at Caltech, who discovered that these quasars were rapidly receding from us due to the overall expansion of the universe and were, therefore, according to Hubble’s law, very distant, highly luminous objects. Quasars are now understood to be powered by hot gas spiraling inward toward supermassive black holes in galactic nuclei.
Astronomers measure mass by using Isaac Newton’s formula for orbiting bodies: v2 = GM/R. If you plug in the orbital velocity of Earth, v = 30 kilometers/second, and the radius of Earth’s orbit, R = 93 million miles, and take the known value of Newton’s gravitational constant G, you can find the Sun’s mass, Msun = 2 × 1033 grams. If you plug in the orbital velocity of our Sun about the center of our galaxy, v = 220 kilometers/second, and the radius of the Sun’s orbit about the center of the galaxy, R = 25,000 light-years, then you can find the mass of our galaxy interior to the orbit of the Sun, about 60 billion solar masses.
Dark matter was needed to explain the stability of galaxies, the rotation rates in their outskirts, and the masses of groups and clusters of galaxies. But what could this dark matter be? Could
Dark matter could be made of weakly interacting massive particles (WIMPs), as proposed by Princeton physicist Jim Peebles. These would be exotic elementary particles, more massive than the proton. They would interact weakly, neither glowing nor significantly interacting with photons or particles of ordinary matter except by gravitation, which affects all particles through the curvature of space. If the dark matter were made of WIMPs, the distribution of mass within galaxy halos would be smooth, consistent with microlensing studies, and dark matter would pass through just as the galaxies do, to end up located in two widely separated lumps just as we see in the Bullet Cluster.
Thus, a number of lines of evidence point to exotic elementary particles as the source of dark matter.
Today it is known as the Virgo Supercluster. Its diameter is about 100 million light-years, and our own Local Group of galaxies is in its outskirts. Our address in space is: Earth, Solar System, Milky Way, Local Group, Virgo Supercluster: clusters within superclusters, meatballs within meatballs.
The Big Bang itself is at the bottom where all the worldlines converge. There is no time before that. In the beginning, space between two distant worldlines is separating faster than the speed of light. This is allowed and indeed predicted by general relativity. Einstein’s theory of special relativity says that a rocket cannot pass you faster than the speed of light, but nothing prohibits the space between particles stretching faster than the speed of light. When space stretches that fast, the two particles cannot exchange photons in the time available since the Big Bang."
"Its abstract stated the following: Observations indicate galaxies are distributed in a filament-dominated weblike structure. Numerical experiments at high and low redshift of viable structure formation theories also show filament-dominance. We present a simple quantitative explanation of why this is so, showing that the final-state web is actually present in embryonic form in the overdensity pattern of the initial fluctuations, with nonlinear dynamics just sharpening the image.
The Sloan Great Wall is so dramatic that one might wonder if it is consistent with the standard CDM inflationary cosmology.
The fact that these simulations agree so well with the observations in both amplitude and shape of the genus curve is a great victory for the standard model of inflation.
The observations suggest the universe stopped decelerating about 6.9 billion years ago and has begun an epoch of accelerated expansion, which has continued ever since.
Extrapolating even further into the future, the dark energy will become ever more dominant as the matter continues to thin out. The universe will continue to expand forever, as the repulsive effects of dark energy continue to accelerate the expansion. In the far future, the geometry of spacetime will approximate de Sitter space."
"As time went on, we would find no new structures from the cosmic web coming into view. Even if we waited till the infinite future, we would see a total number of structures in the cosmic web only a factor of 2.36 times larger than the number of structures we can see today.
Now in this epoch of budget cuts, the National Security Agency has given astronomers two 2.4-meter spy satellite telescopes that it no longer needs! What an unexpected windfall this is for basic research.
In just the past century we have learned that planet Earth is just a tiny speck in a vast cosmos. We have also discovered the architecture of the universe—billions of galaxies linked in a giant cosmic web. As the fossilized remnants of quantum fluctuations made in the first 10−35 seconds of our universe, the cosmic web is the oldest thing we can see. It may also provide clues as to the nature of the potentially vast stretches of time that loom ahead of us in the future.
Here is what Einstein’s equation looks like: Rμν − 1⁄2gμνR = 8πTμν. I just wanted you to see it! Needless to say, it requires a lot of unpacking of mathematical terms to understand it in detail, but putting it simply, the “stuff” of the universe (matter, mass energy, pressure, etc.) causes space and time to curve.
But we are seeing these electrons where they were in the past, 13.8 billion years ago, just 380,000 years after the Big Bang. Where are those same electrons now? They have been expanding outward with the expansion of the universe and are, at the current epoch, about 46 billion light-years away. This is called the comoving distance. "
"General relativity predicts that both energy density and pressure cause space and time (spacetime) to curve. Newton figured that mass alone caused gravity. With his famous equation E = mc2, Einstein proved that energy and mass can be converted into each other and are, therefore, equivalent in their gravitational effects. If Newton had known this, he probably would have agreed that energy could be attractive and that a high density of energy would be greatly attractive. But the idea that pressure is also gravitationally attractive is a new addition by Einstein. As we have discussed, at early times in the hot Big Bang model, the energy density in the universe is dominated by radiation. The energy density of radiation is equal to the number of photons per unit volume times their individual energies. It turns out that radiation itself exerts a pressure as well—photons bouncing off a solar sail on a spacecraft can push it along like a sailboat in the wind.
We are used to thinking that empty space (the vacuum) should have a zero energy density. But Guth proposed that in the early universe the laws of physics were different and there was a different vacuum state giving empty space a high amount of energy per cubic centimeter.
The negative pressure operates in the three spatial directions (width, breadth, depth) and, because it is negative, it has a negative, or repulsive, gravitational effect three times as large as the gravitational attraction of the energy density. That means that the overall effect of this positive energydensity vacuum state is gravitationally repulsive.
It’s rather amazing that, starting from nothing, or nearly nothing, inflation is capable of producing a multiverse containing an infinite number of bubble universes, each infinite in extent, expanding forever, with just the desired form of density fluctuations.
We have a new addition to our cosmic address: Earth, Solar System, Milky Way, Local Group, Virgo Supercluster, Laniakea Supercluster.
As science has become more complex, science collaborations have become larger. The WMAP satellite team that measured the cosmic microwave background grew to 21 members. The Sloan Digital Sky Survey, which I also work on (and will describe shortly), involves about 180 people—but I did not form that group. The Planck Satellite Collaboration reported new measurements of the cosmic microwave background in 2013 with a paper having 277 authors. (Of course, the really BIG science is over in physics, where the ATLAS Collaboration looking for the Higgs boson had a paper with an author list beginning Aad, Abbott, Abdallah, Abdel, ... , and 3,062 more coauthors!) Today, the challenge for young astronomers is to figure out how to fit into the ever- larger collaborations."
"Theorists were quite ready to accept this remarkable picture of an accelerating universe. In fact, Jerry Ostriker and Paul Steinhardt had actually proposed including the cosmological constant to answer a couple of cosmic puzzles in 1995, 2 years before the discovery of the accelerated expansion of the universe. They had argued that if inflation proceeded for many doublings in the early universe, it would be expected in most cases to make the universe truly gigantic today. If that were true, its size today would be much larger than 13.8 billion light-years, making it look relatively flat on scales of 13.8 billion light-years. Inflation, by its inherently excessive stretching, should automatically make the universe very flat, by stretching out inhomogeneities. A flat universe implied Ω0 = 1 (i.e., the observed density in the universe would be essentially equal to the critical density). Guth had always emphasized this point. But if the universe consisted entirely of matter (ordinary matter plus dark matter), this would mean that the expansion was decelerating in such a way that the age of the universe would be equal to only two thirds of the observed Hubble time of 14 billion years. With Ωmatter = 1, that would make the universe only about 9.3 billion years old, somewhat younger than the oldest stars we have found in the galaxy. It was embarrassing. Furthermore, the observations of the dark matter content of the universe stubbornly remained at about Ωmatter = 0.3, not enough to produce a flat universe. However, if we had Ωmatter = 0.35 and Ωdark energy = 0.65, then Ω0 = Ωmatter + Ωdark energy = 1, they argued, making the universe flat and the age of the universe about 14 billion years, older than the oldest stars. Dark energy did not cluster with galaxies and so it would not show up in studies of the amount of dark matter....
"Origin of the Name Cosmic Web
Where did the name cosmic web come from? The first paper to use it in either its title or abstract was the 1995 arXiv preprint posted online by Richard Bond, Lev Kofman, and Dmitry Pogosyan. The title of their paper was “How Filaments Are Woven into the Cosmic Web” (1995)."
"The largest structures in the universe are giant filaments of galaxies stretching between the great clusters—the greatly expanded fossil remnants of initial random quantum fluctuations. Grown by gravity with the help of the mysterious cold dark matter, they form a magnificent, spongelike cosmic web."
"
"By 1983 the overarching battle lines in cosmology were set. Would the American school led by Peebles triumph, or would Zeldovich win in the end? Would it be meatballs or honeycombs? A newly discovered theory for the origin of the universe—inflation—would provide a clue."
"Boltzmann Brains
Once in a great while—once in every 10∧10∧70 years—you will see something called a Boltzmann brain; that is, something as complicated as the human brain will appear at random from the thermal radiation. I have argued (Gott 2008) that although you may see such a brain in the distance if you wait long enough, it would not be a self-conscious intelligent observer—because the thermal radiation is observer dependent.
This becomes important if the universe expands forever; because even though Boltzmann brains would be seen infrequently, there would be an infinite number of them, in the infinite future, and the Boltzmann brains would far outnumber normal intelligent observers made of atoms circling normal stars. That would make us special, and that’s not allowed by the Copernican principle. One might ask, if Boltzmann brains outnumber normal observers by an infinite factor, then why am I not one of them? Such apparent contradictions lead some physicists to rule out an infinite future exponential expansion for our universe.
In this case, according to an argument by Freeman Dyson, intelligent life might continue on forever, in principle, by thinking ever more slowly, using less and less energy, and dumping waste heat into the ever-cooling cosmic microwave background. Intelligent life in the far future would have to become a thin cloud composed of electrons and positrons—the only ordinary matter particles left. These particles would have to produce large, complex structures without annihilating each other—difficult to accomplish in practice but possible in principle."
"Heat death for intelligent life
About 840 billion years from now, the cosmic microwave background photons become redshifted to a lower temperature than the Gibbons and Hawking radiation and become unimportant. The temperature of the universe bottoms out at 7 × 10−31 K, the Gibbons and Hawking temperature. That’s just above absolute zero on the Kelvin scale, about 4 × 1032 times colder than ice water. Still, this is a finite temperature, and as we shall see this has interesting consequences at late times. Eventually, one would come into thermal equilibrium with this thermal radiation, and there would be a heat death for intelligent life.
The stars will have all burnt out by about 10^14 years from now. Protons should decay into positrons and neutrinos, somewhere between 10^34 and 10^64 years from now. Then the heaviest particles left around will be electrons and positrons. They will be so spread out that they can’t find each other to annihilate. About 10^100 years from now, galactic-mass black holes will evaporate by Hawking radiation and blink out in a burst of glory.
Then it will be dark, with nothing to look at but the Gibbons and Hawking thermal radiation from the event horizons of the universe as a whole. It would be like watching static on your television. Now we need some even larger numbers to help us. The number 10^100 is called a googol. We can also write it as 10∧100. Now 10 raised to the googol power is 10∧10∧100 and we call that a googolplex. If you wait long enough, that random static you see in the Gibbons and Hawking radiation will eventually show something interesting (not that anyone would likely be around to observe it). (Remember the old story: if you have monkeys randomly typing and you wait long enough, one of them will eventually produce a copy of one of Shakespeare’s plays by chance.)"
"In this he anticipated quasars—bright galactic nuclei which were indeed mistaken at first for stars in our own galaxy. It was Maarten Schmidt, also at Caltech, who discovered that these quasars were rapidly receding from us due to the overall expansion of the universe and were, therefore, according to Hubble’s law, very distant, highly luminous objects. Quasars are now understood to be powered by hot gas spiraling inward toward supermassive black holes in galactic nuclei.
Astronomers measure mass by using Isaac Newton’s formula for orbiting bodies: v2 = GM/R. If you plug in the orbital velocity of Earth, v = 30 kilometers/second, and the radius of Earth’s orbit, R = 93 million miles, and take the known value of Newton’s gravitational constant G, you can find the Sun’s mass, Msun = 2 × 1033 grams. If you plug in the orbital velocity of our Sun about the center of our galaxy, v = 220 kilometers/second, and the radius of the Sun’s orbit about the center of the galaxy, R = 25,000 light-years, then you can find the mass of our galaxy interior to the orbit of the Sun, about 60 billion solar masses.
Dark matter was needed to explain the stability of galaxies, the rotation rates in their outskirts, and the masses of groups and clusters of galaxies. But what could this dark matter be? Could
Dark matter could be made of weakly interacting massive particles (WIMPs), as proposed by Princeton physicist Jim Peebles. These would be exotic elementary particles, more massive than the proton. They would interact weakly, neither glowing nor significantly interacting with photons or particles of ordinary matter except by gravitation, which affects all particles through the curvature of space. If the dark matter were made of WIMPs, the distribution of mass within galaxy halos would be smooth, consistent with microlensing studies, and dark matter would pass through just as the galaxies do, to end up located in two widely separated lumps just as we see in the Bullet Cluster.
Thus, a number of lines of evidence point to exotic elementary particles as the source of dark matter.
Today it is known as the Virgo Supercluster. Its diameter is about 100 million light-years, and our own Local Group of galaxies is in its outskirts. Our address in space is: Earth, Solar System, Milky Way, Local Group, Virgo Supercluster: clusters within superclusters, meatballs within meatballs.
The Big Bang itself is at the bottom where all the worldlines converge. There is no time before that. In the beginning, space between two distant worldlines is separating faster than the speed of light. This is allowed and indeed predicted by general relativity. Einstein’s theory of special relativity says that a rocket cannot pass you faster than the speed of light, but nothing prohibits the space between particles stretching faster than the speed of light. When space stretches that fast, the two particles cannot exchange photons in the time available since the Big Bang."
"Its abstract stated the following: Observations indicate galaxies are distributed in a filament-dominated weblike structure. Numerical experiments at high and low redshift of viable structure formation theories also show filament-dominance. We present a simple quantitative explanation of why this is so, showing that the final-state web is actually present in embryonic form in the overdensity pattern of the initial fluctuations, with nonlinear dynamics just sharpening the image.
The Sloan Great Wall is so dramatic that one might wonder if it is consistent with the standard CDM inflationary cosmology.
The fact that these simulations agree so well with the observations in both amplitude and shape of the genus curve is a great victory for the standard model of inflation.
The observations suggest the universe stopped decelerating about 6.9 billion years ago and has begun an epoch of accelerated expansion, which has continued ever since.
Extrapolating even further into the future, the dark energy will become ever more dominant as the matter continues to thin out. The universe will continue to expand forever, as the repulsive effects of dark energy continue to accelerate the expansion. In the far future, the geometry of spacetime will approximate de Sitter space."
"As time went on, we would find no new structures from the cosmic web coming into view. Even if we waited till the infinite future, we would see a total number of structures in the cosmic web only a factor of 2.36 times larger than the number of structures we can see today.
Now in this epoch of budget cuts, the National Security Agency has given astronomers two 2.4-meter spy satellite telescopes that it no longer needs! What an unexpected windfall this is for basic research.
In just the past century we have learned that planet Earth is just a tiny speck in a vast cosmos. We have also discovered the architecture of the universe—billions of galaxies linked in a giant cosmic web. As the fossilized remnants of quantum fluctuations made in the first 10−35 seconds of our universe, the cosmic web is the oldest thing we can see. It may also provide clues as to the nature of the potentially vast stretches of time that loom ahead of us in the future.
Here is what Einstein’s equation looks like: Rμν − 1⁄2gμνR = 8πTμν. I just wanted you to see it! Needless to say, it requires a lot of unpacking of mathematical terms to understand it in detail, but putting it simply, the “stuff” of the universe (matter, mass energy, pressure, etc.) causes space and time to curve.
But we are seeing these electrons where they were in the past, 13.8 billion years ago, just 380,000 years after the Big Bang. Where are those same electrons now? They have been expanding outward with the expansion of the universe and are, at the current epoch, about 46 billion light-years away. This is called the comoving distance. "
"General relativity predicts that both energy density and pressure cause space and time (spacetime) to curve. Newton figured that mass alone caused gravity. With his famous equation E = mc2, Einstein proved that energy and mass can be converted into each other and are, therefore, equivalent in their gravitational effects. If Newton had known this, he probably would have agreed that energy could be attractive and that a high density of energy would be greatly attractive. But the idea that pressure is also gravitationally attractive is a new addition by Einstein. As we have discussed, at early times in the hot Big Bang model, the energy density in the universe is dominated by radiation. The energy density of radiation is equal to the number of photons per unit volume times their individual energies. It turns out that radiation itself exerts a pressure as well—photons bouncing off a solar sail on a spacecraft can push it along like a sailboat in the wind.
We are used to thinking that empty space (the vacuum) should have a zero energy density. But Guth proposed that in the early universe the laws of physics were different and there was a different vacuum state giving empty space a high amount of energy per cubic centimeter.
The negative pressure operates in the three spatial directions (width, breadth, depth) and, because it is negative, it has a negative, or repulsive, gravitational effect three times as large as the gravitational attraction of the energy density. That means that the overall effect of this positive energydensity vacuum state is gravitationally repulsive.
It’s rather amazing that, starting from nothing, or nearly nothing, inflation is capable of producing a multiverse containing an infinite number of bubble universes, each infinite in extent, expanding forever, with just the desired form of density fluctuations.
We have a new addition to our cosmic address: Earth, Solar System, Milky Way, Local Group, Virgo Supercluster, Laniakea Supercluster.
As science has become more complex, science collaborations have become larger. The WMAP satellite team that measured the cosmic microwave background grew to 21 members. The Sloan Digital Sky Survey, which I also work on (and will describe shortly), involves about 180 people—but I did not form that group. The Planck Satellite Collaboration reported new measurements of the cosmic microwave background in 2013 with a paper having 277 authors. (Of course, the really BIG science is over in physics, where the ATLAS Collaboration looking for the Higgs boson had a paper with an author list beginning Aad, Abbott, Abdallah, Abdel, ... , and 3,062 more coauthors!) Today, the challenge for young astronomers is to figure out how to fit into the ever- larger collaborations."
"Theorists were quite ready to accept this remarkable picture of an accelerating universe. In fact, Jerry Ostriker and Paul Steinhardt had actually proposed including the cosmological constant to answer a couple of cosmic puzzles in 1995, 2 years before the discovery of the accelerated expansion of the universe. They had argued that if inflation proceeded for many doublings in the early universe, it would be expected in most cases to make the universe truly gigantic today. If that were true, its size today would be much larger than 13.8 billion light-years, making it look relatively flat on scales of 13.8 billion light-years. Inflation, by its inherently excessive stretching, should automatically make the universe very flat, by stretching out inhomogeneities. A flat universe implied Ω0 = 1 (i.e., the observed density in the universe would be essentially equal to the critical density). Guth had always emphasized this point. But if the universe consisted entirely of matter (ordinary matter plus dark matter), this would mean that the expansion was decelerating in such a way that the age of the universe would be equal to only two thirds of the observed Hubble time of 14 billion years. With Ωmatter = 1, that would make the universe only about 9.3 billion years old, somewhat younger than the oldest stars we have found in the galaxy. It was embarrassing. Furthermore, the observations of the dark matter content of the universe stubbornly remained at about Ωmatter = 0.3, not enough to produce a flat universe. However, if we had Ωmatter = 0.35 and Ωdark energy = 0.65, then Ω0 = Ωmatter + Ωdark energy = 1, they argued, making the universe flat and the age of the universe about 14 billion years, older than the oldest stars. Dark energy did not cluster with galaxies and so it would not show up in studies of the amount of dark matter....
July 8, 2018
Mind blowing. Struggled to keep my head above water in parts, despite the author really trying to make accessible. I blame that on my complete lack of familiarity with the subject. Overall got the gist of it. tl;dr THE UNIVERSE IS HUGE, but there is structure that we can understand.
August 18, 2021
A popular description of author's research to learn a shape of the universe. Starting with a historical overview of the subject, the author describes how in his youth his interest in topology led him to getting interested in how the universe looks like at a macro scale. He relates the current knowledge and research based on the modelling of the large mass structures and their possible linkages to dark matter and dark energy.
The book discusses a number of theories on universe's development and the reasons behind his current and predicted future shape. They are supported by modelling the movements of the large structures and the observed data.
The book discusses a number of theories on universe's development and the reasons behind his current and predicted future shape. They are supported by modelling the movements of the large structures and the observed data.
April 25, 2016
The Cosmic Web: Mysterious Architecture of the Universe by J. Richard Gott.
Review by Galen Weitkamp.
In 1986 Margaret Geller, Valerie de Lapparent and John Hulchra published a map of a wedge shaped sector of the universe 730 million lightyears deep, 120 degrees wide and only 6 degrees thick. Almost every one has come across this map somewhere: in a newspaper, a magazine, a book or a lecture. It shows a universe that is not homogeneous on this scale but rather one that is filled with structures composed, not of single galaxies, but clusters of galaxies woven into superclusters that stretch like a glistening web over the black meadow of the cosmos. Deeper and more detailed surveys followed in 1989 revealing The Great Attractor and The Great Wall. Since then the Wilkinson Microwave Anisotropy Probe (WMAP) and the Sloan Digital Sky Survey (SDSS) have been revealing even more of the large scale structure of our universe.
Uncovering, describing and understanding this structure has been and is the life work of J. Richard Gott, professor of astrophysics at Princeton and the author of The Cosmic Web. Is the universe a giant Swiss cheese whose structures are suitably described as the negative space of giant bubble like voids? Or are the strands of luminous matter we see the negative space of a porous sponge of bubbles and tunnels? What’s the difference? The negative space of a swiss cheese is a scattering of distinct bubbles, whereas the negative space of a sponge is another sponge. To see the latter imagine filling all the voids in a sponge with a liquid cement. After the cement hardens remove the sponge and what is left over has the shape of another sponge.
Gott’s work and that of many others over the past decades decides in favor of the sponge. Moreover it would seem this spongey structure is the natural effect of expansion on initially random fluctuations in the distribution of mass/energy in a very early cold dark matter universe.
The Cosmic Web is written for the interested layperson. There are no mathematical formulae to worry the reader, but it is full of solid physics, detailed explanations, enlightening metaphors and entertaining histories.
Review by Galen Weitkamp.
In 1986 Margaret Geller, Valerie de Lapparent and John Hulchra published a map of a wedge shaped sector of the universe 730 million lightyears deep, 120 degrees wide and only 6 degrees thick. Almost every one has come across this map somewhere: in a newspaper, a magazine, a book or a lecture. It shows a universe that is not homogeneous on this scale but rather one that is filled with structures composed, not of single galaxies, but clusters of galaxies woven into superclusters that stretch like a glistening web over the black meadow of the cosmos. Deeper and more detailed surveys followed in 1989 revealing The Great Attractor and The Great Wall. Since then the Wilkinson Microwave Anisotropy Probe (WMAP) and the Sloan Digital Sky Survey (SDSS) have been revealing even more of the large scale structure of our universe.
Uncovering, describing and understanding this structure has been and is the life work of J. Richard Gott, professor of astrophysics at Princeton and the author of The Cosmic Web. Is the universe a giant Swiss cheese whose structures are suitably described as the negative space of giant bubble like voids? Or are the strands of luminous matter we see the negative space of a porous sponge of bubbles and tunnels? What’s the difference? The negative space of a swiss cheese is a scattering of distinct bubbles, whereas the negative space of a sponge is another sponge. To see the latter imagine filling all the voids in a sponge with a liquid cement. After the cement hardens remove the sponge and what is left over has the shape of another sponge.
Gott’s work and that of many others over the past decades decides in favor of the sponge. Moreover it would seem this spongey structure is the natural effect of expansion on initially random fluctuations in the distribution of mass/energy in a very early cold dark matter universe.
The Cosmic Web is written for the interested layperson. There are no mathematical formulae to worry the reader, but it is full of solid physics, detailed explanations, enlightening metaphors and entertaining histories.
January 11, 2017
La ricerca della struttura dell'universo, per capirne le origini.
Ho comprato questo libro perché appassionato di astrofisica e perché non avevo mai letto nulla in merito alle grandi strutture rilevate su scale enormi nell'Universo visibile. E' impressionante capire (o quantomeno intuire) quello che negli ultimi decenni è stato scoperto in merito alla trama del nostro Universo, e quello che mi impressiona ogni volta è pensare alla scala dei fenomeni e delle strutture osservate, al fatto che guardando lontanissimo si guarda indietro nel tempo, fino a 13 miliardi di anni fa... strutture immense che permettono di comprendere come il tutto si è originato, strutture immense risultato di fluttuazioni quantistiche in un universo primordiale di dimensioni infinitesimali.. do 4 stelle al libro perché non l'ho trovato scorrevole e piacevole da leggere come altri libri divulgativi di Brian Greene (La Trama del Cosmo), Caleb Sharf (I Motori della Gravità, sui Buchi neri) o Jim Al-Khalili (l'affascinate La Fisica della Vita), ma potrebbe essere dovuto ad un mio limite che leggo non con lo scopo di studiare questa materia ma di affascinarmi (cercando comunque di "portare a casa" quanto più possibile). Comunque come avete forse potuto intuire, questa lettura mi ha lasciato affascinato, perché l'universo, infinitamente piccolo o infinitamente grande, non può che affascinare... allo stesso modo rimango affascinato dall'uomo, dagli studiosi e da dove riescono a spingere la propria mente e i propri studi dal nostro piccolo puntino nel cosmo fino agli orizzonti più lontani.
Ho comprato questo libro perché appassionato di astrofisica e perché non avevo mai letto nulla in merito alle grandi strutture rilevate su scale enormi nell'Universo visibile. E' impressionante capire (o quantomeno intuire) quello che negli ultimi decenni è stato scoperto in merito alla trama del nostro Universo, e quello che mi impressiona ogni volta è pensare alla scala dei fenomeni e delle strutture osservate, al fatto che guardando lontanissimo si guarda indietro nel tempo, fino a 13 miliardi di anni fa... strutture immense che permettono di comprendere come il tutto si è originato, strutture immense risultato di fluttuazioni quantistiche in un universo primordiale di dimensioni infinitesimali.. do 4 stelle al libro perché non l'ho trovato scorrevole e piacevole da leggere come altri libri divulgativi di Brian Greene (La Trama del Cosmo), Caleb Sharf (I Motori della Gravità, sui Buchi neri) o Jim Al-Khalili (l'affascinate La Fisica della Vita), ma potrebbe essere dovuto ad un mio limite che leggo non con lo scopo di studiare questa materia ma di affascinarmi (cercando comunque di "portare a casa" quanto più possibile). Comunque come avete forse potuto intuire, questa lettura mi ha lasciato affascinato, perché l'universo, infinitamente piccolo o infinitamente grande, non può che affascinare... allo stesso modo rimango affascinato dall'uomo, dagli studiosi e da dove riescono a spingere la propria mente e i propri studi dal nostro piccolo puntino nel cosmo fino agli orizzonti più lontani.
August 19, 2017
I enjoyed this book quite a bit. I liked that it wasn't long, and instead got to the point without going through a bunch of twists and turns that weren't necessary. The book was particularly fascinating for me as I just spent my first summer working within the field of theoretical physics and cosmology, so I found the book to be right up my alley. I also find that the author explains concepts very well *without* simplifying them. It seems like so many science books water down the technical details to the point that everything is qualitative. That's not what you get here, and so I enjoyed the book a lot. The images were spectacular as well.
One thing I didn't like: all the footnotes were at the end of the book, so I didn't read them as I came across each footnote in the text since I didn't want to flip back and forth. It would have been nice to have them within the text (at the bottom of the page).
One thing I didn't like: all the footnotes were at the end of the book, so I didn't read them as I came across each footnote in the text since I didn't want to flip back and forth. It would have been nice to have them within the text (at the bottom of the page).
January 11, 2018
I've read quite a few nonfiction astronomy books over the past several years, and this one is by far the toughest read.
While most books try to bring the concepts down a bit for a more general audience to understand, this book doesn't really do that. It's quite complicated and there are many equations and theories discussed within. Some discussions gave me a better understanding of the topic than I had before (inflation), but there were quite a few I just could not get my head around, no matter how closely I read through it.
Definitely interesting, but be ready to really pay attention and feel like you are taking a class on the topic.
While most books try to bring the concepts down a bit for a more general audience to understand, this book doesn't really do that. It's quite complicated and there are many equations and theories discussed within. Some discussions gave me a better understanding of the topic than I had before (inflation), but there were quite a few I just could not get my head around, no matter how closely I read through it.
Definitely interesting, but be ready to really pay attention and feel like you are taking a class on the topic.
November 5, 2017
Un bellissimo libro divulgativo sulla cosmologia, che parla in particolare della struttura dell'universo, la "ragnatela cosmica" formata dai filamenti di galassie che collegano grandi ammassi, e della teoria inflazionaria, secondo cui nei primi istanti della vita dell'universo le sue dimensioni sarebbero aumentato di moltissimi ordini di grandezza. Alcune parti non sono semplicissime, rispetto ad altri libri divulgativi che ho letto su argomenti analoghi è un po' più difficile, ma nel complesso si riesce a seguire bene con un po' di impegno.
June 2, 2018
Il libro è dedicato alla struttura macroscopica dell'universo e nel far ciò spiega i più recenti sviluppi degli Studi svolti in merito. In questo diventa inevitabile parlare di materia oscura, energia oscura e inflazione cosmica, pertanto chi è interessato anche a questi argomenti troverà in questo libro molti spunti. Rispetto ad altri libri come l'Universo Elegante di Brian Greene è senz'altro meno comprensibile, persino complicato in alcuni passaggi, tuttavia l'ho trovato di grande interesse e molto aggiornato.
April 9, 2018
A fine book on a very specific topic: the observable universe’s topology (sponge-like with webs of higher density left over from early quantum fluctuations) and fate (possibly eternal expansion with baby inflationary universes springing forth to start anew). I gave it just 3 stars for purely selfish reasons: physical cosmology, it turns out, doesn’t interest me as much as philosophical cosmology, and the book is somewhat heavy on equations that will be meaningful only to advanced students of physics.
February 7, 2017
So the universe is probably constructed like a sponge: cluster of galaxies connected to each other by filaments of galaxies that can be longer than a billions light years. The largest known structures in the universe. Except that no one knows how big the universe is. Or if ours is only one in an infinite of a multiverse. Still fascinating.
August 17, 2019
I probably misjudged the target audience on this, because much of it was over my head. Still an interesting read though, and I'm considering seeking more basic cosmology books so I can start to get a grasp on some of the denser material here.
December 20, 2018
Took me a while to finish this - sometimes I could only absorb a few pages worth at a time, before having to stop and think about it! But don't let that scare you - it's actually pretty well written for a non-physicist audience. Gott uses some good metaphors and visual thought-experiments to explain a lot of the scientific concepts - but he packs a lot of information into this short book so sometimes those metaphors are milked for everything he can get out of them.
It mainly covers how a community of scientists came up with our current understanding of the large-scale structure of the universe - it's all about how galaxies form clusters along filaments with large voids in between. That sentence doesn't really do it justice though - it's the story of how they came up with mind-blowing simulations like this: https://www.youtube.com/watch?v=74Isy... which show what our universe looks like on the very large scale. I kept on having to remind myself the whole way through the book, especially whenever there were diagrams, that the individual data points or dots they are talking about are entire galaxies, not individual stars.
Early on he tells the story of how astronomers around a century ago started getting the first data indicating the universe was much, much bigger than anyone previously thought. It follows a familiar pattern for scientists writing books on their subject matter - a bit of history and context of the field, laying groundwork for the uninitiated, part-autobiography, but it's not all about his own work - he does a very good job of giving credit to many different people who have made contributions along the way.
A particularly interesting angle is how the more correct model of the universe actually came out of Soviet scientists. But because they usually only published in Russian, and the same physicists doing this astronomy also were involved in the Soviet nuclear program and not allowed out of the country, there was a delay in their ideas reaching the west, the author was one of the early people to open up communications with them.
I found it interesting the way he deals with dark energy - in a number of podcasts I have listened to, physicists talking about dark energy have been hesitant to say much more than "dark energy is a property of empty space making our universe expand faster than we can explain, but we don't know what it is or why it's there", and I haven't come across many explanations willing to state much more detail than that. Gott pretty casually explains that it is a non-zero positive energy state of vacuum space - i.e. even empty space has incredibly small yet finite and positive energy associated with it, not zero. He then goes on to discuss the implications of this for the future evolution of the universe in some pretty trippy ways. Granted, he doesn't seem to put forward any reasons as to why dark energy is there - he seems to just see it as a property of our universe similar to other scientific constants.
All up I found this a very enjoyable read, and it is truly mind-boggling to think about filaments of galaxies across the universe - there is a huge sensation of awe and wonder just thinking about it. It added a lot to my amateur understanding of cosmology and astrophysics - while I won't claim to have understood everything presented, I feel like I got enough of it to appreciate the subject matter. I might have to re-read sometime.
It mainly covers how a community of scientists came up with our current understanding of the large-scale structure of the universe - it's all about how galaxies form clusters along filaments with large voids in between. That sentence doesn't really do it justice though - it's the story of how they came up with mind-blowing simulations like this: https://www.youtube.com/watch?v=74Isy... which show what our universe looks like on the very large scale. I kept on having to remind myself the whole way through the book, especially whenever there were diagrams, that the individual data points or dots they are talking about are entire galaxies, not individual stars.
Early on he tells the story of how astronomers around a century ago started getting the first data indicating the universe was much, much bigger than anyone previously thought. It follows a familiar pattern for scientists writing books on their subject matter - a bit of history and context of the field, laying groundwork for the uninitiated, part-autobiography, but it's not all about his own work - he does a very good job of giving credit to many different people who have made contributions along the way.
A particularly interesting angle is how the more correct model of the universe actually came out of Soviet scientists. But because they usually only published in Russian, and the same physicists doing this astronomy also were involved in the Soviet nuclear program and not allowed out of the country, there was a delay in their ideas reaching the west, the author was one of the early people to open up communications with them.
I found it interesting the way he deals with dark energy - in a number of podcasts I have listened to, physicists talking about dark energy have been hesitant to say much more than "dark energy is a property of empty space making our universe expand faster than we can explain, but we don't know what it is or why it's there", and I haven't come across many explanations willing to state much more detail than that. Gott pretty casually explains that it is a non-zero positive energy state of vacuum space - i.e. even empty space has incredibly small yet finite and positive energy associated with it, not zero. He then goes on to discuss the implications of this for the future evolution of the universe in some pretty trippy ways. Granted, he doesn't seem to put forward any reasons as to why dark energy is there - he seems to just see it as a property of our universe similar to other scientific constants.
All up I found this a very enjoyable read, and it is truly mind-boggling to think about filaments of galaxies across the universe - there is a huge sensation of awe and wonder just thinking about it. It added a lot to my amateur understanding of cosmology and astrophysics - while I won't claim to have understood everything presented, I feel like I got enough of it to appreciate the subject matter. I might have to re-read sometime.
November 3, 2020
Have you ever read a pop science book and thought this is just too shallow? What I've read is not science but some stories and approximations that in the interest of conveying information have strayed too far from the "real" content. I wish they could simply write real science without asking us to imagine some balloons inflated or deflated. This book has heard your frustrations, there is no imagine this or that here, in their stead are actual equations, countless in fact with results being given in their specification and to the nearest decimal point. I applaud Richard Gott for doing that. Sometimes you have to trust the audience to wade through the murky waters of technical content.
The title pretty much sums up the book's content. It takes the reader through the topology of the universe and speculates on what the actual landscape might look like; sponge or Swiss cheese. There a lot of chapters that explain how using density calculations and several other factors we can come to know whether it's like a sponge or cheese. The book should be of interest if you are interested in cosmic architecture or just what is out there.
There are good reasons though why publishers tell authors to take out all the equations and stick to stories and thought experiments to convey information as opposed to feeding the reader hard facts. This book is a buffet of abstractions. There were sentences where I had to keep track of 3 separate abstract concepts and when a fourth and fifth were piled on, I just gave up. I don't have such an interest in cosmic topology to suffer through some concepts. It did not help that a lot of what the book was talking about is what I call speculative science, a field built on the backbone of mathematics and computer simulations with minimal observational data. I could not shake off the feeling that whatever am frying my brain cells over could be the modern age ether or phlogiston theory. I don't know, may be am not that interested in inflation theory and what it might mean to the cosmic architecture, give me Cassini images to a number raised to ten power some outrageous figure. If cosmic topology is something that gives you warmth inside, check this one out I'll be outside watching grass grow.
The title pretty much sums up the book's content. It takes the reader through the topology of the universe and speculates on what the actual landscape might look like; sponge or Swiss cheese. There a lot of chapters that explain how using density calculations and several other factors we can come to know whether it's like a sponge or cheese. The book should be of interest if you are interested in cosmic architecture or just what is out there.
There are good reasons though why publishers tell authors to take out all the equations and stick to stories and thought experiments to convey information as opposed to feeding the reader hard facts. This book is a buffet of abstractions. There were sentences where I had to keep track of 3 separate abstract concepts and when a fourth and fifth were piled on, I just gave up. I don't have such an interest in cosmic topology to suffer through some concepts. It did not help that a lot of what the book was talking about is what I call speculative science, a field built on the backbone of mathematics and computer simulations with minimal observational data. I could not shake off the feeling that whatever am frying my brain cells over could be the modern age ether or phlogiston theory. I don't know, may be am not that interested in inflation theory and what it might mean to the cosmic architecture, give me Cassini images to a number raised to ten power some outrageous figure. If cosmic topology is something that gives you warmth inside, check this one out I'll be outside watching grass grow.
July 7, 2025
Whew! this book is amazing and difficult and exciting. Gott, who played a major role in understanding the architecture of the Universe, explains the history of our understanding of how the universe is designed and what it might look like in the future.
Some of this book was over my head. While Gott gives simple explanations of complex understandings, such as quantum tunneling, he also offers the mathematical in scientific proofs. How one discovery leads to another. How one theory is proved correct by observation while another is proved wrong. So, some parts of the book were quite difficult to fully grasp, overall Gott does a great job of explaining the complex understandings clearly.
Since Gott was right in the middle of discovering the "Cosmic Web", I enjoyed learning of Gott's personal simulations and theories, as well has how his High School science fair project helped lead to this discovery much later in life.
Gott also gives the best explanation of the "multiverse" theory that I have ever heard as well as why this theory has become one of the leading theories.
Some of this book was over my head. While Gott gives simple explanations of complex understandings, such as quantum tunneling, he also offers the mathematical in scientific proofs. How one discovery leads to another. How one theory is proved correct by observation while another is proved wrong. So, some parts of the book were quite difficult to fully grasp, overall Gott does a great job of explaining the complex understandings clearly.
Since Gott was right in the middle of discovering the "Cosmic Web", I enjoyed learning of Gott's personal simulations and theories, as well has how his High School science fair project helped lead to this discovery much later in life.
Gott also gives the best explanation of the "multiverse" theory that I have ever heard as well as why this theory has become one of the leading theories.
September 12, 2019
This book takes you on a journey from Edwin Hubble determining that our Milky Way is not the sole island universe to the whole shebang... i.e., the Cosmic Web. Necessarily, it has a little math, but if you got by high school algebra you shouldn't have a problem. Speaking of high school, Dr. Gott discusses his high school science project that is amusing and should be inspiring for all.
On the way in this journey, you'll learn little topology, dark matter, dark energy, the expanding universe, the accelerating expanding universe, inflation, multiverses, and toward the end of the read: 'w'.
In 2010, one of the most important quests in Astrophysics was to determine the value of w, where w is the ratio of the pressure associated with dark energy and the energy density of dark energy; as of 2014, w = -.95 +- .07; this related to the date of our universe, and the its strange architecture.
Enjoy!
On the way in this journey, you'll learn little topology, dark matter, dark energy, the expanding universe, the accelerating expanding universe, inflation, multiverses, and toward the end of the read: 'w'.
In 2010, one of the most important quests in Astrophysics was to determine the value of w, where w is the ratio of the pressure associated with dark energy and the energy density of dark energy; as of 2014, w = -.95 +- .07; this related to the date of our universe, and the its strange architecture.
Enjoy!
October 27, 2025
I read this book in order to learn more about the history of observations and simulations of the galaxies on the largest scales. This book is part that and part autobiographical. It can be quite scientific at times. So I wouldn’t consider it for the general public.
It could be quite dry and not all that engaging (for me, at least), even though it tells a very interesting story. The book did give several nice suggestions for other books to read on the topic, also written by scientists that has been directly involved in our understanding of the cosmic web, so I am looking forward to reading some of them.
It could be quite dry and not all that engaging (for me, at least), even though it tells a very interesting story. The book did give several nice suggestions for other books to read on the topic, also written by scientists that has been directly involved in our understanding of the cosmic web, so I am looking forward to reading some of them.
September 12, 2024
This is an interesting book that describes the work of one scientist (J. Richard Gott) and his colleagues as they study the large-scale structure of the universe. Using topological mathematics and astronomical observations, they have determined that the structure of the universe can be described best as a cosmic "web" in which galaxies and galaxy clusters are connected together in long filaments stretching millions of light-years in distance, separated by vast voids of space containing very little matter compared to the galaxies themselves. The writing style is simple, straightforward, almost matter-of-fact, even though a lot of what is described is theoretical but supported by observation and interpretation. It's not an exciting story, but it is interesting and makes a lot of sense.
April 20, 2021
The clearest explanation of what the largest structures of the universe are like (superclusters of Galaxies in a sponge-like shape) and the ultimate fate of the universe depending on the nature of dark energy.
May 16, 2022
Reads like a science journal for scientists. Interesting topic, but not an enjoyable read at all.
April 23, 2020
Gli argomenti trattati vanno oltre il senso comune dell'astrofilia. Fare una panoramica su quello che conosciamo dell'universo, peggio ancora quello che non conosciamo, risulta un compito arduo e poco scontato. Questo libro porta la mente di fronte alle domande più estreme che uno scienziato possa concepire. Ho trovato curioso come l'autore abbia deciso di fare ciò tramite storie, fatti, citazioni e nomi (il suo tante volte) che hanno dedicato la loro intera vita a queste domande, tanto inutili quanto meravigliose. Lo consiglio ad ogni studente di astrofisica, è un ottimo strumento per ispirarsi quando si deve chiedere una tesi. Godete per quel senso di smisurato vuoto che c'è tra noi e la comprensione del cosmo, oltre che per l'impaginatura da dio.
May 28, 2016
For the record, the only reason I could follow along with this AT ALL is because I recently read a book on dark matter, and I've been studying basic astronomy on my own. This may be "introductory," strictly speaking, but definitely not recommended for anyone without a grounded understanding of dark matter, physics, etc.
Gott basically takes the reader through what we've thought the universe is like throughout history. "We're at the center. The sun's at the center. We're alone. The universe is finite," and so on. The latter portion of the book explains the current theory. Though the most popular analogies have been meatball vs. swiss, he advocates for a 3D model of the concept. It was hard to wrap my mind around, but still incredibly fascinating. I wonder if it'll hold up 100 years from now.
Okay, but what REALLY freaked me out? There's a picture in here that SHOWS dark matter. I mean, okay, it just highlights the region in blue. But the fact that we can (sort of) detect it? That's crazy!
Gott basically takes the reader through what we've thought the universe is like throughout history. "We're at the center. The sun's at the center. We're alone. The universe is finite," and so on. The latter portion of the book explains the current theory. Though the most popular analogies have been meatball vs. swiss, he advocates for a 3D model of the concept. It was hard to wrap my mind around, but still incredibly fascinating. I wonder if it'll hold up 100 years from now.
Okay, but what REALLY freaked me out? There's a picture in here that SHOWS dark matter. I mean, okay, it just highlights the region in blue. But the fact that we can (sort of) detect it? That's crazy!
December 24, 2016
Ho scritto il mio giudizio su Amazon, non appena verrà pubblicato farò il copia e incolla. Eccolo: Confesso che mi sono perso nella lettura di questo libro. Non avrei dovuto affrontare una lettura del genere. Non sono un ragno, non sono un architetto, mi piacciono i misteri ma non ho mai capito la parola cosmo. Forse tutto quello che l'autore di questo libro ha detto poteva essere detto in parole più semplici, con meno formule, grafici ed immagini per un ignorante come me, cose di non facile interpretazione. La colpa, è ovvio, è tutta della mia ignoranza. Dopo le prime 100 pagine confesso di avere fatto una corsa verso la fine, ho preso subito tra le mani il libro di Ungaretti e mi sono riletto il famoso verso: "M'illumino d'immenso". Così ho capito tutto. Ma per non prendermi troppo sul serio mi sono ricordato anche di quella frase che lessi da qualche parte e che riguarda l'uomo. In maniera poco elegante veniva definito "un peto nell'universo". Perdonatemi, ma io mi sono sentito così in questa ragnatela ...
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