Posts Tagged ‘Big Bang’
“The universe is under no obligation to make sense to you”*…
Still, we try… In a consideration of three new books, the estimable Sean Carroll brings us up to date on the state of play…
Should scientists be embarrassed that they can’t settle on a definition for the Big Bang? The cosmologist Will Kinney describes it as the “physical theory of the hot infant universe,” while Wikipedia goes for the more elaborate “a physical theory that describes how the universe expanded from an initial state of high density and temperature.” The first refers only to early times, while the latter seems to extend to subsequent times as well. The physicist and science writer Tony Rothman offers the pithier “the universe’s origin,” the theoretical physicist Thomas Hertog suggests that it is the “primeval state” of cosmic history, and a NASA website gives us “the idea that the universe began as just a single point.” These seem to refer to one moment at the start of things, rather than the universe’s life since then.
All of these sources (except NASA, unfortunately) capture something correct. The confusion stems both from the inherent ambiguity of using ordinary language to describe novel scientific concepts and from the state of modern cosmology itself. Cosmology is the study of the universe on the largest scales. So it ignores details of stars and planets, focusing on galaxies and even bigger structures, up to the universe as a whole. Modern cosmology is only about a century old, as it wasn’t until the 1920s that astronomers determined that our own Milky Way is just one of a large number of galaxies and the origin and evolution of them all could be studied together. And it wasn’t until the 1990s that the field matured into the one that exists today, featuring precision measurements and ultralarge datasets.
Dealing as it does with some of the most profound questions about the nature of the cosmos, cosmological research has always involved a vigorous give-and-take between rampant speculation and unanticipated discoveries. Its practitioners have long been fond of spinning purportedly inviolate physical principles from their personal intuitions about how reality should work. But cosmology remains an empirical science—a cherished belief can be quickly swept away by a solid measurement.
The present moment in the science of cosmology is one of consolidation, as we have successfully incorporated the lessons of some impressive discoveries made near the turn of the twenty-first century. Yet crucially important questions remain unanswered, especially about what exactly happened at the onset of the expanding space that evolved into our contemporary universe. It is therefore a good time for books that take stock of where we are and what might come next, and that illustrate which puzzles modern physicists choose to take seriously.
This much we know: we live in a galaxy, the Milky Way, containing around 200 billion stars. There are something like a trillion galaxies in our observable universe, distributed almost uniformly through space. Stars and galaxies condensed out of an originally nearly smooth distribution of matter. Distant galaxies are moving apart from one another. Extrapolating backward, we reach a hot, densely packed configuration about 13.8 billion years ago. We can observe the remnants of this early period in nearly uniform cosmic background radiation coming from every direction in the sky.
The Big Bang model is precisely this general picture, of a universe that expands and cools out of a smooth, hot primordial state. It is well understood and almost universally accepted among modern cosmologists. The Big Bang event is a hypothetical moment when the whole thing might have started, at which the temperature and density are supposed to have been literally infinite—a “singularity,” in physics parlance. This is why the NASA definition above is unambiguously wrong: the Big Bang event has nothing to do with “a single point” in space—it refers to a moment in time.
Nobody knows whether there actually was such an event. To be honest, there probably wasn’t. Einstein’s theory of general relativity predicts that such a singularity would have happened, but most physicists think this signals a breakdown in the theory rather than being an accurate description of the physical world. A prediction of infinitely big physical quantities is apt to be a sign that we don’t have the right theoretical understanding…
[Starting with Einstein’s unification of space-time in 1905, Carroll explains the implications of quantum theory, in particular on the question of the expansion of the universe. Using the three (very different, but complementary) books under consideration, he unpacks the issues and demonstrates the way in which scientific theories about the origin of the universe often involve a vigorous give-and-take between speculation and discovery…]
… Taken together, these three books provide an illuminating view of the state of modern cosmology. There are established results, laudable efforts to connect promising hypotheses to a flood of incoming data, and brave speculations about the physical and metaphysical unknown. They are all notably well written for the genre and will keep readers entertained as they are educated. We can marvel at both how much scientists have learned about the universe and how much we have yet to understand.
The state of cosmology (and a look at science at work): “A First Time for Everything,” from @seanmcarroll.bsky.social in @nybooks.com.
* Neil deGrasse Tyson
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As we wrestle with reality, we might spare a thought for a major (if, in the end, incorrect) character in tale that Carroll tells: Fred Hoyle; he died on this date in 2001. A prominent astronomer, he formulated the theory of stellar nucleosynthesis. But he is rather better remembered for his controversial stances on other scientific matters—in particular his rejection of the (as Carroll observes, now widely-accepted) “Big Bang” theory– a term he coined, derisively, in an episode of his immensely-popular series The Nature of the Universe on BBC radio– and his promotion of panspermia as the source of life on Earth (or maybe the traffic was in the other direction?).
“It’s peculiar. It’s special. There’s very little of it, but it has this pivotal role in the universe.”*…
One of the oldest, scarcest elements in the universe has given us treatments for mental illness, ovenproof casserole dishes, and electric cars. Increasingly, our response to climate change seems to depend on it. But how much do we really know about lithium? Jacob Baynham explains…
The universe was born small, unimaginably dense and furiously hot. At first, it was all energy contained in a volume of space that exploded in size by a factor of 100 septillion in a fraction of a second. Imagine it as a single cell ballooning to the size of the Milky Way almost instantaneously. Elementary particles like quarks, photons and electrons were smashing into each other with such violence that no other matter could exist. The primordial cosmos was a white-hot smoothie in a blender.
One second after the Big Bang, the expanding universe was 10 billion degrees Kelvin. Quarks and gluons had congealed to make the first protons and neutrons, which collided over the course of a few minutes and stuck in different configurations, forming the nuclei of the first three elements: two gases and one light metal. For the next 100 million years or so, these would be the only elements in the vast, unblemished fabric of space before the first stars ignited like furnaces in the dark to forge all other matter.
Almost 14 billion years later, on the third rocky planet orbiting a young star in a distal arm of a spiral galaxy, intelligent lifeforms would give names to those first three elements. The two gases: hydrogen and helium. The metal: lithium.
This is the story of that metal, a powerful, promising and somehow still mysterious element on which those intelligent lifeforms — still alone in the universe, as far as they know — have pinned their hopes for survival on a planet warmed by their excesses…
[Baynham tells the story of this remarkable element, the development of it many uses (in psychopharmacology, in materials science, and of course in electronics– especially batteries), the rigors of extracting it for those purposes, and the challenges that its scarcity– and its potency– present…]
… Long before cell phones and climate anxiety and the Tesla Model Y, long before dinosaurs and the first creatures that climbed out of the ocean to walk on land, long before the Earth formed from swirling masses of cosmic matter heavy enough to coalesce, back, way back, to the infant universe, to the dawn of matter itself, there were just three types of atoms — three elements in the blank canvas of space. One of them was lithium. It was light, fragile and extremely reactive, its one outer electron tenuously held in place.
Everything we have done with lithium, all its wondrous applications in energy, industry and psychiatry, somehow hinges on this basic structure, a sort of magic around which we’re increasingly engineering our future. Lightness is usually associated with abundance on the periodic table — almost 99% of the mass of the universe is just the lightest two elements. Lithium, however, is the third lightest element and still mysteriously scarce…
That most elemental of elements: “The Secret, Magical Life of Lithium,” from @JacobBaynham in @noemamag.com.
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As we muse on materials, we might send densely-packed birthday greetings to Philip W. Anderson; he was born on this date in 1923. A theoretical physicist, he shared (with John H. Van Vleck and Sir Nevill F. Mott) the 1977 Nobel Prize for Physics for his research on semiconductors, superconductivity, and magnetism. Anderson made contributions to the theories of localization, antiferromagnetism, symmetry breaking including a paper in 1962 discussing symmetry breaking in particle physics, leading to the development of the Standard Model around 10 years later), and high-temperature superconductivity, and to the philosophy of science through his writings on emergent phenomena. He was a pioneer in the field that he named: condensed matter physics, which has found applications in semiconductor and laserr technology, magnetic storage, liquid crystals, optical fibers, nanotechnology, quantum computing, and biomedicine.
“It is clear that there is no classification of the Universe that is not arbitrary and full of conjectures. The reason for this is very simple: we do not know what kind of thing the universe is.”*…
… Still, scientists try. Ethan Siegel on the current state of play– with special attention to whether or not our cosmic landscape is endless or not, and why the Universe is so uniform on large scales, but so non-uniform on smaller scales…
13.8 billion years ago, our Universe as we know it began with the hot Big Bang, which gave rise to a primordial soup of particles and antiparticles that led to the planets, stars, and galaxies we know today. The hot Big Bang itself was set up by a preceding phase known as cosmic inflation, but only the final tiny fraction-of-a-second gets imprinted onto our observable Universe. What we can observe about the Universe is finite, but what about the unobservable parts that lie beyond it: are they finite or infinite? What the data can tell us is limited, but here’s what we think and why…
Read on to find out: “Is the Universe finite or infinite?” from @StartsWithABang in @bigthink.
* Jorge Luis Borges, in “The Analytical Language of John Wilkins”
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As we stargaze, we might send sunny birthday greetings to Herbert Friedman; he was born on this date in 1916. A physicist and astronomer, he made seminal contributions to the study of solar radiation. Friedman joined the Naval Research Laboratory in 1940 and developed defense-related radiation detection devices during WW II. In 1949, he obtained the first scientific proof that X rays emanate from the sun, when he directed the firing into space of a V-2 rocket carrying a detecting instrument. Through subsequent rocket astronomy, he also produced the first ultraviolet map of celestial bodies, and gathered information for the theory that stars are being continuously formed, on space radiation affecting Earth, and on the nature of gases in space. Friedman also made fundamental advances in the application of x rays to material analysis.
“For what are myths if not the imposing of order on phenomena that do not possess order in themselves? And all myths, however they differ from philosophical systems and scientific theories, share this with them, that they negate the principle of randomness in the world.”*…
And we humans are, as Kit Yates explains, myth-making animals…
Unfortunately, when it comes to understanding random phenomena, our intuition often lets us down. Take a look at the image below. Before you read the caption, see if you can pick out the data set generated using truly uniform random numbers for the coordinates of the dots (i.e., for each point, independent of the others, the horizontal coordinate is equally likely to fall anywhere along the horizontal axis and the vertical coordinate is equally likely to fall anywhere along the vertical).
The truly randomly distributed points in the figure are those in the left-most image. The middle image represents the position of ants’ nests that, although distributed with some randomness, demonstrate a tendency to avoid being too close together in order not to overexploit the same resources. The territorial Patagonian seabirds’ nesting sites, in the right-most image, exhibit an even more regular and well-spaced distribution, preferring not to be too near to their neighbors when rearing their young. The computer-generated points, distributed uniformly at random in the left-hand image, have no such qualms about their close proximity.
If you chose the wrong option, you are by no means alone. Most of us tend to think of randomness as being “well spaced.” The tight clustering of dots and the frequent wide gaps of the genuinely random distribution seem to contradict our inherent ideas of what randomness should look like…
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… As a case in point, after noticing a disproportionate number of Steely Dan songs playing on his iPod shuffle, journalist Steven Levy questioned Steve Jobs directly about whether “shuffle” was truly random. Jobs assured him that it was and even got an engineer on the phone to confirm it. A follow-up article Levy wrote in Newsweek garnered a huge response from readers having similar experiences, questioning, for example, how two Bob Dylan songs shuffled to play one after the other (from among the thousands of songs in their collections) could possibly be random.
We ascribe meaning too readily to the clustering that randomness produces, and, consequently, we deduce that there is some generative force behind the pattern. We are hardwired to do this. The “evolutionary” argument holds that tens of thousands of years ago, if you were out hunting or gathering in the forest and you heard a rustle in the bushes, you’d be wise to play it safe and to run away as fast as you could. Maybe it was a predator out looking for their lunch and by running away you saved your skin. Probably, it was just the wind randomly whispering in the leaves and you ended up looking a little foolish—foolish, but alive and able to pass on your paranoid pattern-spotting genes to the next generation…
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This… is just one example of the phenomenon known in the psychology literature as pareidolia, in which an observer interprets an ambiguous auditory or visual stimulus as something they are familiar with. This phenomenon, otherwise known as “patternicity,” allows people to spot shapes in the clouds and is the reason why people think they see a man in the moon. Pareidolia is itself an example of the more general phenomenon of apophenia, in which people mistakenly perceive connections between and ascribe meaning to unrelated events or objects. Apophenia’s misconstrued connections lead us to validate incorrect hypotheses and draw illogical conclusions. Consequently, the phenomenon lies at the root of many conspiracy theories—think, for example, of extraterrestrial seekers believing that any bright light in the sky is a UFO.
Apophenia sends us looking for the cause behind the effect when, in reality, there is none at all. When we hear two songs by the same artist back-to-back, we are too quick to cry foul in the belief that we have spotted a pattern, when in fact these sorts of clusters are an inherent feature of randomness. Eventually, the dissatisfaction caused by the clustering inherent to the iPod’s genuinely random shuffle algorithm led Steve Jobs to implement the new “Smart Shuffle” feature on the iPod, which meant that the next song played couldn’t be too similar to the previous song, better conforming to our misconceived ideas of what randomness looks like. As Jobs himself quipped, “We’re making it less random to make it feel more random.”…
“Why Randomness Doesn’t Feel Random,” an excerpt from How to Expect the Unexpected: The Science of Making Predictions—and the Art of Knowing When Not To, by @Kit_Yates_Maths in @behscientist.
* Stanislaw Lem
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As we ponder purported patterns, we might send carefully-discerned birthday greetings to a man who did in fact find a pattern (or at least a meaning) in what might have seemed random and meaningless: Robert Woodrow Wilson; he was born on this date in 1936. An astronomer, he detected– with Bell Labs colleague Arno Penzias– cosmic microwave background radiation: “relic radiation”– that’s to say, the “sound “– of the Big Bang… familiar to those of us old enough to remember watching an old-fashioned television after the test pattern was gone (when there was no broadcast signal received): the “fuzz” we saw and the static-y sounds we heard, were that “relic radiation” being picked up.
Their 1964 discovery earned them the 1978 Nobel Prize in Physics.
“It is well to remember that the entire universe, with one trifling exception, is composed of others”*…
For centuries, scientific discoveries have suggested humanity occupies no privileged place in the universe. But as Mario Livio argues, studies of worlds beyond our solar system could place meaningful new limits on our existential mediocrity…
When the Polish polymath Nicolaus Copernicus proposed in 1543 that the sun, rather than the Earth, was the center of our solar system, he did more than resurrect the “heliocentric” model that had been devised (and largely forgotten) some 18 centuries earlier by the Greek astronomer Aristarchus of Samos. Copernicus—or, rather, the “Copernican principle” that bears his name—tells us that we humans are nothing special. Or, at least, that the planet on which we live is not central to anything outside of us; instead, it’s just another ordinary world revolving around a star.
Our apparent mediocrity has only ascended in the centuries that have passed since Copernicus’s suggestion. In the middle of the 19th century Charles Darwin realized that rather than being the “crown of creation,” humans are simply a natural product of evolution by means of natural selection. Early in the 20th century, astronomer Harlow Shapley deepened our Copernican cosmic demotion, showing that not only the Earth but the whole solar system lacks centrality, residing in the Milky Way’s sleepy outer suburbs rather than the comparatively bustling galactic center. A few years later, astronomer Edwin Hubble showed that galaxies other than the Milky Way exist, and current estimates put the total number of galaxies in the observable universe at a staggering trillion or more.
Since 1995 we have discovered that even within our own Milky Way roughly one of every five sunlike or smaller stars harbors an Earth-size world orbiting in a “Goldilocks” region (neither too hot nor too cold) where liquid water may persist on a rocky planetary surface. This suggests there are at least a few hundred million planets in the Milky Way alone that may in principle be habitable. In roughly the same span of time, observations of the big bang’s afterglow—the cosmic microwave background—have shown that even the ordinary atomic matter that forms planets and people alike constitutes no more than 5 percent of the cosmic mass and energy budget. With each advance in our knowledge, our entire existence retreats from any possible pinnacle, seemingly reduced to flotsam adrift at the universe’s margins.
Believe it or not, the Copernican principle doesn’t even end there. In recent years increasing numbers of physicists and cosmologists have begun to suspect—often against their most fervent hopes—that our entire universe may be but one member of a mind-numbingly huge ensemble of universes: a multiverse.
Interestingly though, if a multiverse truly exists, it also suggests that Copernican cosmic humility can only be taken so far.
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The implications of the Copernican principle may sound depressing to anyone who prefers a view of the world regarding humankind as the central or most important element of existence, but notice that every step along the way in extending the Copernican principle represented a major human discovery. That is, each decrease in the sense of our own physical significance was the result of a huge expansion in our knowledge. The Copernican principle teaches us humility, yes, but it also reminds us to keep our curiosity and passion for exploration alive and vibrant…
Fascinating: “How Far Should We Take Our Cosmic Humility?“, from @Mario_Livio in @sciam.
* John Holmes (the poet)
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As we ponder our place, we might send carefully-observed birthday greetings to Arno Penzias; he was born on this date in 1933. A physicist and radio astronomer, he and Robert Wilson, a collegue at Bell Labs, discovered the cosmic microwave background radiation, which helped establish the Big Bang theory of cosmology– work for which they shared the 1978 Nobel Prize in Physics.
MB radiation is something that anyone old enough to have watched broadcast (that’s to say, pre-cable/streaming) television) has seen:
The way a television works is relatively simple. A powerful electromagnetic wave is transmitted by a tower, where it can be received by a properly sized antenna oriented in the correct direction. That wave has additional signals superimposed atop it, corresponding to audio and visual information that had been encoded. By receiving that information and translating it into the proper format (speakers for producing sound and cathode rays for producing light), we were able to receive and enjoy broadcast programming right in the comfort of our own homes for the first time. Different channels broadcasted at different wavelengths, giving viewers multiple options simply by turning a dial.
Unless, that is, you turned the dial to channel 03.
Channel 03 was — and if you can dig up an old television set, still is — simply a signal that appears to us as “static” or “snow.” That “snow” you see on your television comes from a combination of all sorts of sources:
– human-made radio transmissions,
– the Sun,
– black holes,
– and all sorts of other directional astrophysical phenomena like pulsars, cosmic rays and more.
But if you were able to either block all of those other signals out, or simply took them into account and subtracted them out, a signal would still remain. It would only by about 1% of the total “snow” signal that you see, but there would be no way of removing it. When you watch channel 03, 1% of what you’re watching comes from the Big Bang’s leftover glow. You are literally watching the cosmic microwave background…
“This Is How Your Old Television Set Can Prove The Big Bang“
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