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Posts Tagged ‘geography

“If and when all the laws governing physical phenomena are finally discovered, and all the empirical constants occurring in these laws are finally expressed through the four independent basic constants, we will be able to say that physical science has reached its end”*…

The fine-structure constant was introduced in 1916 to quantify the tiny gap between two lines in the spectrum of colors emitted by certain atoms. The closely spaced frequencies are seen here through a Fabry-Pérot interferometer.

As fundamental constants go, the speed of light, c, enjoys all the fame, yet c’s numerical value says nothing about nature; it differs depending on whether it’s measured in meters per second or miles per hour. The fine-structure constant, by contrast, has no dimensions or units. It’s a pure number that shapes the universe to an astonishing degree — “a magic number that comes to us with no understanding,” as Richard Feynman described it. Paul Dirac considered the origin of the number “the most fundamental unsolved problem of physics.”

Numerically, the fine-structure constant, denoted by the Greek letter α (alpha), comes very close to the ratio 1/137. It commonly appears in formulas governing light and matter. “It’s like in architecture, there’s the golden ratio,” said Eric Cornell, a Nobel Prize-winning physicist at the University of Colorado, Boulder and the National Institute of Standards and Technology. “In the physics of low-energy matter — atoms, molecules, chemistry, biology — there’s always a ratio” of bigger things to smaller things, he said. “Those ratios tend to be powers of the fine-structure constant.”

The constant is everywhere because it characterizes the strength of the electromagnetic force affecting charged particles such as electrons and protons. “In our everyday world, everything is either gravity or electromagnetism. And that’s why alpha is so important,” said Holger Müller, a physicist at the University of California, Berkeley. Because 1/137 is small, electromagnetism is weak; as a consequence, charged particles form airy atoms whose electrons orbit at a distance and easily hop away, enabling chemical bonds. On the other hand, the constant is also just big enough: Physicists have argued that if it were something like 1/138, stars would not be able to create carbon, and life as we know it wouldn’t exist.

Physicists have more or less given up on a century-old obsession over where alpha’s particular value comes from; they now acknowledge that the fundamental constants could be random, decided in cosmic dice rolls during the universe’s birth. But a new goal has taken over.

Physicists want to measure the fine-structure constant as precisely as possible. Because it’s so ubiquitous, measuring it precisely allows them to test their theory of the interrelationships between elementary particles — the majestic set of equations known as the Standard Model of particle physics. Any discrepancy between ultra-precise measurements of related quantities could point to novel particles or effects not accounted for by the standard equations. Cornell calls these kinds of precision measurements a third way of experimentally discovering the fundamental workings of the universe, along with particle colliders and telescopes…

In a new paper in the journal Nature, a team of four physicists led by Saïda Guellati-Khélifa at the Kastler Brossel Laboratory in Paris reported the most precise measurement yet of the fine-structure constant. The team measured the constant’s value to the 11th decimal place, reporting that α = 1/137.03599920611. (The last two digits are uncertain.)

With a margin of error of just 81 parts per trillion, the new measurement is nearly three times more precise than the previous best measurement in 2018 by Müller’s group at Berkeley, the main competition. (Guellati-Khélifa made the most precise measurement before Müller’s in 2011.) Müller said of his rival’s new measurement of alpha, “A factor of three is a big deal. Let’s not be shy about calling this a big accomplishment”… largely ruling out some proposals for new particles

A team in Paris has made the most precise measurement yet of the fine-structure constant, killing hopes for a new force of nature: “Physicists Nail Down the ‘Magic Number’ That Shapes the Universe.”

[TotH to MK]

* George Gamow

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As we ponder precision, we might spare a thought for Persian polymath Omar Khayyam; the mathematician, philosopher, astronomer, epigrammatist, and poet died on this date in 1131.  While he’s probably best known to English-speakers as a poet, via Edward FitzGerald’s famous translation of the quatrains that comprise the Rubaiyat of Omar Khayyam, Omar was one of the major mathematicians and astronomers of the medieval period.  He is the author of one of the most important works on algebra written before modern times, the Treatise on Demonstration of Problems of Algebra (which includes a geometric method for solving cubic equations by intersecting a hyperbola with a circle).  His astronomical observations contributed to the reform of the Persian calendar.  And he made important contributions to mechanics, geography, mineralogy, music, climatology, and Islamic theology.

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“The beaver told the rabbit as they stared at the Hoover Dam: No, I didn’t build it myself, but it’s based on an idea of mine”*…

Of all the things that humanity builds from concrete or stone, there are few structures that influence the surface of Earth quite as profoundly as a dam.

By blocking the flow of a river, we dare to defy gravity’s pull on water from mountain to estuary – and influence the trajectory of geology itself. A dam does so much more than submerge a valley to create a reservoir: it transforms a river’s natural course, accruing silt and sediment at an artificial barrier, and dampening water’s erosional force downstream

Their vertiginous walls, striking shapes and deep foundations will also leave a unique archaeological imprint. Some of these engineered monoliths are so enormous that they may be preserved for millennia.

Meanwhile, dams can also bring deep changes for the people who live nearby, and the generations that follow them. When a government in a distant capital decides to exploit its rivers, destruction of local homes, farmland and livelihoods often follows. For example, while the rest of the world focused on Covid-19 earlier this year, an entire ancient town in Turkey was lost to rising reservoir waters. Long after we are gone, future archaeologists will study such submerged settlements and may wonder why we let them go for the sake of short-term politics and energy demand.

The effects can be felt a long way from home, too. Damming rivers that wind through continents, like the Nile in Africa, can withhold valuable water and power from countries downstream, forever changing the trajectories of those nations…

Few human structures can change a landscape quite like a dam– a pictorial essay: “How dams have reshaped our planet.”

* Nobel laureate Charles H. Townes

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As we interrogate interruption, we might recall that it was on this date in 1570 that the All Saints Flood broke dikes and overwhelmed the Dutch (and parts of the German) coast. At least 20,000 people were drowned and many times that many left homeless; livestock was lost in huge numbers; and winter stocks of food and fodder were destroyed. In Zeeland the small islands Wulpen, Koezand, Cadzand, and Stuivezand were permanently lost.

Drawing by Hans Moser in 1570 of the flood

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Written by LW

November 1, 2020 at 1:01 am

“Like guns and crosses, maps can be good or bad, depending on who’s holding them, who they’re aimed at, how they’re used, and why”*…

 

World Map

“A New and Accurat [sic] Map of the World,” John Speed 1626. For background, see here

 

We expect maps to tell us the truth. They seem trustworthy, after all: when you need to figure out how to get from Copley Square to Fenway Park, or if you’re interested in comparing the income levels of Boston’s neighborhoods, the first reference material you’re likely to seek out is a map.

But maps, truth, and belief have a complicated relationship with one another. Every map is a representation of reality, and every representation, no matter how accurate and honest, involves simplification, symbolization, and selective attention. Even when a map isn’t actively trying to deceive its readers, it still must reduce the complexity of the real world, emphasizing some features and hiding others. Compressing the round globe onto a flat sheet of paper, and converting places, people, and statistics into symbols, lines, and colors is a process inherently fraught with distortion.

Meanwhile, what we understand to be true is based on what we have seen in maps. For example, how do you know that New Zealand is an island off the coast of Australia if you’ve never been on a ship in the Tasman Sea or flown up in space to see it yourself? That fact about the world is one you can believe because you’ve seen it reproduced over and over again in maps produced by people and institutions that you trust…

Because they seem to show the world how it “really is,” maps produce a powerful sense of trust and belief.  But maps and data visualizations can never communicate a truth without any perspective at all.  They are social objects whose meaning and power are produced by written and symbolic language and whose authority is determined by the institutions and contexts in which they circulate.  From the Boston Public Library’s Norman B. Leventhal Map & Education Center, a remarkable online exhibit that explores the many ways in which maps and data can mislead: BENDING LINES: Maps and Data from Distortion to Deception. (Lots of fascinating information and LOTS of glorious maps!)

See also: “How to Detect the Distortions of Maps.”

And lest we underestimate the innate challenges facing cartographers, “The U.S. Is Getting Shorter, as Mapmakers Race to Keep Up.”

* Mark Monmonier, How to Lie with Maps

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As we aspire to accuracy, we might recall that it was on this date in 1784 that Élisabeth Thible became the first women to ascend in an untethered balloon (eight months after the first manned balloon flight).  When the balloon left the ground Thible, dressed as the Roman goddess Minerva, and her pilot, Monsieur Fleurant sang two duets from Monsigny’s La Belle Arsène, a celebrated opera of the time.  The flight lasted 45 minutes, covered four kilometers, and achieved an estimated height of 1,500 meters.  Their audience included King Gustav III of Sweden, in whose honor the balloon was named.

Thible

Élisabeth Thible on a later flight

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“In a series of forms graduating insensibly from some apelike creature to man as he now exists, it would be impossible to fix on any definite point where the term ‘man’ ought to be used”*…

 

fingerbone

Homo sapiens finger bone, dating back some 86,000 years, found at a site called Al Wusta in Saudi Arabia

 

Darwin turns out to right about the difficulty of dating the emergence of man, not only for the reason he intended (that our emergence from prior species was so gradual as to be indetectable as an “event”) but also because it’s turning out to be difficult to date the earliest examples we can agree are “man” and to figure out when they reached the places they settled…

The Nefud Desert is a desolate area of orange and yellow sand dunes. It covers approximately 25,000 square miles of the Arabian Peninsula. But tens of thousands of years ago, this area was a lush land of lakes, with a climate that may have been kinder to human life.

On a January afternoon in 2016, an international team of archaeologists and paleontologists was studying the surface of one ancient lake bed at a site called Al Wusta in the Nefud’s landscape of sand and gravel. Their eyes were peeled for fossils, bits of stone tools, and any other signs that might remain from the region’s once-verdant past.

Suddenly, Iyad Zalmout, a paleontologist working for the Saudi Geological Survey, spotted what looked like a bone. With small picks and brushes, he and his colleagues removed the find from the ground.

We knew it [was] important,” Zalmout recalled in an email. It was the first direct evidence of any large primate or hominid life in the area. In 2018, lab tests revealed that this specimen was a finger bone from an anatomically modern human who would have lived at least 86,000 years ago.

Prior to this Al Wusta discovery, evidence in the form of stone tools had suggested some human presence in the Nefud between 55,000 and 125,000 years ago. To anthropologists, “human” and “hominin” can mean any of a number of species closely related to our own. The finger bone was the oldest Homo sapiens find in the region.

The bone’s dating contradicts a well-established narrative in the scientific community. Findings, particularly from the area of modern-day Israel, Jordan, and Lebanon, known as the Levant region, have led to the understanding that H. sapiens first made their way out of Africa no earlier than 120,000 years ago, likely migrating north along the Mediterranean coast. These people settled in the Levant and their descendants—or those from a subsequent early human migration out of Africa—traveled into Europe tens of thousands of years later.

Only later, that story goes, did they journey into parts of Asia, such as Saudi Arabia. By some estimates, then, anatomically modern humans would not have been in what is now Al Wusta until about 50,000 years ago.

The fingerbone, then, adds a twist to the tale of how and when our species left the African continent and, with many starts and stops, populated much of the rest of the earth. A new crop of discoveries, particularly from Asia, suggest that modern humans first left Africa some 200,000 years ago, taking multiple different routes…

Politics, geography, and tradition have long focused archaeological attention on the evolution of Homo sapiens in Europe and Africa. Now, new research is challenging old ideas by showing that early human migrations unfolded across Asia far earlier than previously known: “Will Asia Rewrite Human History?

* Charles Darwin, The Descent of Man

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As we return to roots, we might spare a thought for Jean-Léon-François Tricart; he died on this date in 2003.  A physical geographer and climatic geomorphologist known for his extensive regional studies in numerous countries of Africa.

Tricart was a pioneer in many fields of physical geography including the study of a phenomenon central to the migration of early Homo Sapiens, the major dynamic role of climate in landscape evolution.

Screen Shot 2020-05-04 at 4.41.59 PM source

 

“When I was a kid my parents moved a lot, but I always found them”*…

 

pangea-with-modern-borders-1200

 

Pangea was the latest in a line of supercontinents in Earth’s history.

Pangea began developing over 300 million years ago, eventually making up one-third of the earth’s surface. The remainder of the planet was an enormous ocean known as Panthalassa.

As time goes by, scientists are beginning to piece together more information on the climate and patterns of life on the supercontinent. Similar to parts of Central Asia today, the center of the landmass is thought to have been arid and inhospitable, with temperatures reaching 113ºF (45ºC). The extreme temperatures revealed by climate simulations are supported by the fact that very few fossils are found in the modern day regions that once existed in the middle of Pangea. The strong contrast between the Pangea supercontinent and Panthalassa is believed to have triggered intense cross-equatorial monsoons.

By this unique point in history, plants and animals had spread across the landmass, and animals (such as dinosaurs) were able to wander freely across the entire expanse of Pangea…

Since the average continent is only moving about 1 foot (0.3m) every decade, it’s unlikely you’ll ever be alive to see an epic geographical revision to the world map.

However, for whatever life exists on Earth roughly 300 million years in the future, they may have front row seats in seeing the emergence of a new supercontinent: Pangea Proxima…

 

More– including how it happened and a larger version of the image above– at “Incredible Map of Pangea With Modern-Day Borders.”

* Rodney Dangerfield

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As we go with the flow, we might send historic birthday greetings to Dorothy Annie Elizabeth Garrod; she was born on this date in 1892.  An archaeologist who specialized in the Palaeolithic period, she was the first women to hold a chair at an Oxbridge university, serving as of Disney Professor of Archaeology at the University of Cambridge from 1939 to 1952.

200px-Dorothy_Garrod source

 

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