Posts Tagged ‘Cosmology’
“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.
…
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“
“The sciences of cryptography and mathematics are very elegant, pure sciences. I found that the ends for which these pure sciences are used are less elegant.”*…
Mary, Queen of Scots wrote 57 encrypted messages during her captivity in England; until recently, all but 7 of them were believed lost. Meilan Solly tells the tale of their discovery and decryption…
Over the course of her 19 years in captivity, Mary, Queen of Scots, wrote thousands of letters to ambassadors, government officials, fellow monarchs and conspirators alike. Most of these missives had the same underlying goal: securing the deposed Scottish queen’s freedom. After losing her throne in 1567, Mary had fled to England, hoping to find refuge at her cousin Elizabeth I’s court. (Mary’s paternal grandmother, Margaret Tudor, was the sister of Elizabeth’s father, Henry VIII.) Instead, the English queen imprisoned Mary, keeping her under house arrest for nearly two decades before ordering her execution in 1587.
Mary’s letters have long fascinated scholars and the public, providing a glimpse into her relentless efforts to secure her release. But the former queen’s correspondence often raises more questions than it answers, in part because Mary took extensive steps to hide her messages from the prying eyes of Elizabeth’s spies. In addition to folding the pages with a technique known as letterlocking, she employed ciphers and codes of varying complexity.
More than 400 years after Mary’s death, a chance discovery by a trio of code breakers is offering new insights into the queen’s final years. As the researchers write in the journal Cryptologia, they originally decided to examine a cache of coded notes housed at the National Library of France as part of a broader push to “locate, digitize, transcribe, decipher and analyze” historic ciphers. Those pages turned out to be 57 of Mary’s encrypted letters, the majority of which were sent to Michel de Castelnau, the French ambassador to England, between 1578 and 1584. All but seven were previously thought to be lost…
What they found and how they made sense of it: “Code Breakers Discover—and Decipher—Long-Lost Letters by Mary, Queen of Scots,” from @meilansolly in @SmithsonianMag.
* Jim Sanborn, the sculptor who created the encrypted Kryptos sculpture at CIA headquarters
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As we crack codes, we might spare a thought for a rough contemporary of Mary’s, a man who refused to communicate in code: Giordano Bruno. A Dominican friar, philosopher, mathematician, and astronomer whose concept of the infinite universe expanded on Copernicus’s model, he was the first European to understand the universe as a continuum where the stars we see at night are identical in nature to the Sun. Bruno’s views were considered dangerously heretical by the (Roman) Inquisition, which imprisoned him in 1592; after eight years of refusals to recant, on this date in 1600, he was burned at the stake.
“To see a world in a grain of sand and a heaven in a wildflower”*…
Where, exactly is Heaven? Stephen Reid Case explains how a very concrete, physical answer to that question became much less concrete…
The Christian concept of heaven, so familiar today from popular depictions of clouds and haloed angels, was an invention – one that came about as early Christians interpreted their religious writings in the context of the Greek culture in which their movement grew up. Christian writers combined Plato’s ideas about the soul’s ascent to the sky at death with Aristotle’s understanding of the structure of the universe, a combination that allowed them to apply a cosmological framework to terms like ‘heaven of heavens’, as well as the ascents, described in the New Testament, of both Jesus and Paul. By the Middle Ages, anyone who uttered the words ‘Our Father, who art in heaven …’ had a clear spatial understanding of where heaven was: God dwelt in the third heaven, above the heaven of the air and the heaven of the stars. This third heaven, the empyrean, became an article of Christian faith – until the new cosmology of Copernicus and Galileo placed the Sun rather than Earth in the centre of the universe. This transformation from an Earth-centred to a Sun-centred universe did not simply displace Earth; it destroyed heaven as a place within the cosmos.
If I asked my astronomy students where heaven was located, I would no doubt receive a classroom full of bewildered stares, despite the fact that I teach at a Christian university – where the majority of students believe in both heaven and the afterlife. When pressed, they might offer thoughts about heaven being a different plane of reality or perhaps another dimension. They believe, but they don’t conceptualise heaven as a location; it is not a part of their spatial understanding of the universe. For most of the history of Christianity, though, the opposite was true…
For hundreds of years, Christians knew exactly where heaven was: above us and above the stars. Then came the new cosmologists: “Where God dwelt.”
* William Blake, “Auguries of Innocence” l. 1 (ca. 1803)
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As we muse on metaphor and morphology, we might recall that it was on this date in 1972 that the Apollo 17 mission launched; on their way to the moon, about 18,000 miles from the Earth, astronauts Harrison Schmitt and Ron Evans took the photo now known as “The Blue Marble”– one of the most reproduced images in history.
“It is difficult to fully appreciate how much our picture of the universe has changed in the span of a single human lifetime”*…
… and it continues to change…
Our universe could be the mirror image of an antimatter universe extending backwards in time before the Big Bang. So claim physicists in Canada, who have devised a new cosmological model positing the existence of an “antiuniverse” which, paired to our own, preserves a fundamental rule of physics called CPT symmetry. The researchers still need to work out many details of their theory, but they say it naturally explains the existence of dark matter.
Standard cosmological models tell us that the universe – space, time and mass/energy – exploded into existence some 14 billion years ago and has since expanded and cooled, leading to the progressive formation of subatomic particles, atoms, stars and planets.
However, Neil Turok of the Perimeter Institute for Theoretical Physics in Ontario reckons that these models’ reliance on ad-hoc parameters means they increasingly resemble Ptolemy’s description of the solar system. One such parameter, he says, is the brief period of rapid expansion known as inflation that can account for the universe’s large-scale uniformity. “There is this frame of mind that you explain a new phenomenon by inventing a new particle or field,” he says. “I think that may turn out to be misguided.”
nstead, Turok and his Perimeter Institute colleague Latham Boyle set out to develop a model of the universe that can explain all observable phenomena based only on the known particles and fields. They asked themselves whether there is a natural way to extend the universe beyond the Big Bang – a singularity where general relativity breaks down – and then out the other side. “We found that there was,” he says.
The answer was to assume that the universe as a whole obeys CPT symmetry. This fundamental principle requires that any physical process remains the same if time is reversed, space inverted and particles replaced by antiparticles. Turok says that this is not the case for the universe that we see around us, where time runs forward as space expands, and there’s more matter than antimatter.
Instead, says Turok, the entity that respects the symmetry is a universe–antiuniverse pair. The antiuniverse would stretch back in time from the Big Bang, getting bigger as it does so, and would be dominated by antimatter as well as having its spatial properties inverted compared to those in our universe [as per the illustration above]…
More at “Our universe has antimatter partner on the other side of the Big Bang, say physicists,” in @PhysicsWorld.
Apposite: “The Big Bang no longer means what it used to.”
* Lawrence M. Krauss, A Universe from Nothing: Why There Is Something Rather Than Nothing
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As we debate doppelgangers, we might send chronologically-accurate birthday greetings to Louis Essen; he was born on this date in 1908. A physicist, he is best remembered for his measurements of time– he invented the quartz crystal ring clock and the first practical atomic clock. His cesium-beam atomic clock ultimately changed the way time is measured: the cesium atom’s natural frequency was formally recognized as the new international unit of time in 1967; the second was defined as exactly 9,192,631,770 oscillations or cycles of the cesium atom’s resonant frequency, replacing the old “second” which had been defined in terms of the Earth’s motion.
Perhaps unsurprisingly, given Essen’s punctilious dedication to accuracy, he was a critic of Einstein’s theory of relativity, particularly as it related to time dilation. Moreover, we note (with an eye to the item above) that Essen’s clocks measured time in only one direction…
“Horror vacui”*…
Recently, (Roughly) Daily took a look at nothing– and the perplexing philosophical questions that it raises. Today, Charlie Wood examines nothing’s physical manifestation, the vacuum, and the similarly perplexing questions it raises for physicists…
Millennia ago, Aristotle asserted that nature abhors a vacuum, reasoning that objects would fly through truly empty space at impossible speeds. In 1277, the French bishop Etienne Tempier shot back, declaring that God could do anything, even create a vacuum.
Then a mere scientist pulled it off. Otto von Guericke invented a pump to suck the air from within a hollow copper sphere, establishing perhaps the first high-quality vacuum on Earth. In a theatrical demonstration in 1654, he showed that not even two teams of horses straining to rip apart the watermelon-size ball could overcome the suction of nothing. [See illustration above.]
Since then, the vacuum has become a bedrock concept in physics, the foundation of any theory of something. Von Guericke’s vacuum was an absence of air. The electromagnetic vacuum is the absence of a medium that can slow down light. And a gravitational vacuum lacks any matter or energy capable of bending space. In each case the specific variety of nothing depends on what sort of something physicists intend to describe. “Sometimes, it’s the way we define a theory,” said Patrick Draper, a theoretical physicist at the University of Illinois.
As modern physicists have grappled with more sophisticated candidates for the ultimate theory of nature, they have encountered a growing multitude of types of nothing. Each has its own behavior, as if it’s a different phase of a substance. Increasingly, it seems that the key to understanding the origin and fate of the universe may be a careful accounting of these proliferating varieties of absence.
“We’re learning there’s a lot more to learn about nothing than we thought,” said Isabel Garcia Garcia, a particle physicist at the Kavli Institute for Theoretical Physics in California. “How much more are we missing?”
So far, such studies have led to a dramatic conclusion: Our universe may sit on a platform of shoddy construction, a “metastable” vacuum that is doomed — in the distant future — to transform into another sort of nothing, destroying everything in the process.
Nothing started to seem like something in the 20th century, as physicists came to view reality as a collection of fields: objects that fill space with a value at each point (the electric field, for instance, tells you how much force an electron will feel in different places). In classical physics, a field’s value can be zero everywhere so that it has no influence and contains no energy. “Classically, the vacuum is boring,” said Daniel Harlow, a theoretical physicist at the Massachusetts Institute of Technology. “Nothing is happening.”
But physicists learned that the universe’s fields are quantum, not classical, which means they are inherently uncertain. You’ll never catch a quantum field with exactly zero energy…
For an explanation of how key to understanding the origin and fate of the universe may be a more complete understanding of the vacuum: “How the Physics of Nothing Underlies Everything,” from @walkingthedot in @QuantaMagazine.
* attributed to Aristitole, and usually “translated,” as above, “Nature abhors a vacuum”
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As we noodle on nought, we might spare a thought for Hugo Gernsback, a Luxemborgian-American inventor, broadcast pioneer, writer, and publisher; he died on this date in 1967 at the age of 83.
Gernsback held 80 patents at the time of his death; he founded radio station WRNY, was involved in the first television broadcasts and is considered a pioneer in amateur radio. But it was a writer and publisher that he probably left his most lasting mark: In 1926, as owner/publisher of the magazine Modern Electrics, he filled a blank spot in his publication by dashing off the first chapter of a series called “Ralph 124C 41+.” The twelve installments of “Ralph” were filled with inventions unknown in 1926, including “television” (Gernsback is credited with introducing the word), fluorescent lighting, juke boxes, solar energy, television, microfilm, vending machines, and the device we now call radar.
The “Ralph” series was an astounding success with readers; and later that year Gernsback founded the first magazine devoted to science fiction, Amazing Stories. Believing that the perfect sci-fi story is “75 percent literature interwoven with 25 percent science,” he coined the term “science fiction.”
Gernsback was a “careful” businessman, who was tight with the fees that he paid his writers– so tight that H. P. Lovecraft and Clark Ashton Smith referred to him as “Hugo the Rat.”
Still, his contributions to the genre as publisher were so significant that, along with H.G. Wells and Jules Verne, he is sometimes called “The Father of Science Fiction”; in his honor, the annual Science Fiction Achievement awards are called the “Hugos.”
(Coincidentally, today is also the birthday– in 1906– of Philo T. Farnsworth, the man who actually did invent television…)
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