Tag: Saturday Night Science

Contributor Post Created with Sketch. Saturday Night Science: Bending Spacetime in the Basement

 

Balance built from materials available to ArchimedesOne of the things I detested about being a little kid was that every time I thought of something really cool to do, I was invariably thwarted by my little brother shouting, “Mom! Kelvin’s mixing rocket fuel in the bathtub again!” or “Mom! Kelvin’s making a submarine out of the old refrigerator!

Well, middle age has its drawbacks, but at least you can undertake a project like this without fear of getting nipped in the bud at the cry, “Mom! Kelvin’s down in the basement bending spacetime!”. It’s important to recall the distinction between “grownup” and “grown up”. Let’s us grownups head for the basement to bend some serious spacetime.

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Contributor Post Created with Sketch. Saturday Night Science: Planck

 

“Planck” by Brandon R. BrownTheoretical physics is usually a young person’s game. Many of the greatest breakthroughs have been made by researchers in their twenties, just having mastered existing theories while remaining intellectually flexible and open to new ideas. Max Planck, born in 1858, was an exception to this rule. He spent most of his twenties living with his parents and despairing of finding a paid position in academia. He was 36 when he took on the project of understanding heat radiation, and 42 when he explained it in terms which would launch the quantum revolution in physics. He was in his fifties when he discovered the zero-point energy of the vacuum, and remained engaged and active in science until shortly before his death in 1947 at the age of 89. As theoretical physics editor for the then most prestigious physics journal in the world, Annalen der Physik, in 1905 he approved publication of Einstein’s special theory of relativity, embraced the new ideas from a young outsider with neither a Ph.D. nor an academic position, extended the theory in his own work in subsequent years, and was instrumental in persuading Einstein to come to Berlin, where he became a close friend.

Sometimes the simplest puzzles lead to the most profound of insights. At the end of the nineteenth century, the radiation emitted by heated bodies was such a conundrum. All objects emit electromagnetic radiation due to the thermal motion of their molecules. If an object is sufficiently hot, such as the filament of an incandescent lamp or the surface of the Sun, some of the radiation will fall into the visible range and be perceived as light. Cooler objects emit in the infrared or lower frequency bands and can be detected by instruments sensitive to them. The radiation emitted by a hot object has a characteristic spectrum (the distribution of energy by frequency), and has a peak which depends only upon the temperature of the body. One of the simplest cases is that of a black body, an ideal object which perfectly absorbs all incident radiation. Consider an ideal closed oven which loses no heat to the outside. When heated to a given temperature, its walls will absorb and re-emit radiation, with the spectrum depending upon its temperature. But the equipartition theorem, a cornerstone of statistical mechanics, predicted that the absorption and re-emission of radiation in the closed oven would result in a ever-increasing peak frequency and energy, diverging to infinite temperature, the so-called ultraviolet catastrophe. Not only did this violate the law of conservation of energy, it was an affront to common sense: closed ovens do not explode like nuclear bombs. And yet the theory which predicted this behaviour, the Rayleigh-Jeans law, made perfect sense based upon the motion of atoms and molecules, correctly predicted numerous physical phenomena, and was correct for thermal radiation at lower temperatures.

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Contributor Post Created with Sketch. Saturday Night Science: Paper

 

“Paper” by Mark KurlanskyOne of the things that makes us human is our use of extrasomatic memory: we invent ways to store and retrieve things outside our own brains. It’s as if when the evolutionary drive which caused the brains of our ancestors to grow over time reached its limit, due to the physical constraints of the birth canal, we applied the cleverness of our bulging brains to figure out not only how to record things for ourselves, but to pass them on to other individuals and transmit them through time to our successors.

This urge to leave a mark on our surroundings is deeply-seated and as old as our species. Paintings at the El Castillo site in Spain have been dated to at least 40,800 years before the present. Complex paintings of animals and humans in the Lascaux Caves in France, dated around 17,300 years ago, seem strikingly modern to observers today. As anybody who has observed young children knows, humans do not need to be taught to draw: the challenge is teaching them to draw only where appropriate.

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Contributor Post Created with Sketch. Saturday Night Science: The Victorian Internet

 

“The Victorian Internet” by Tom StandageImagine a global network, in fact, a network of networks. Messages travel across continents and under the sea to remote lands in a matter of seconds. Newspapers receive dispatches from foreign capitals and distant battlefields as soon as events transpire. Business and finance have become global, quotes from stock and commodity exchanges reach investors and management nearly instantly, and money can be transferred among banks at close to the speed of light. Businesses find themselves in a new competitive environment, where instant communication means they can reduce inventories and rely on suppliers to fill orders on demand, and customers can easily compare the price and delivery offered by suppliers around the world.

Diplomats and military commanders, accustomed to operating with a great deal of autonomy and discretion, now find themselves under constant scrutiny and second-guessing by their superiors, and required to report and justify their every action. Police have at their disposal a new way to track down offenders that even the swiftest malefactor cannot outrun, while criminals are discovering new ways to ply their trade. The need of individuals, companies, and governments for privacy in their affairs versus the wish of governments to snoop upon them has intensified the eternal arms race between codemakers and codebreakers. Utopian thinkers hail the new age of instant communication and foresee the ushering in of an age of permanent peace as misunderstandings that have led to conflict dissolve in a flood of international conversation. A new culture is emerging, where those versed in the new technology, mostly young people, can find employment anywhere regardless of their pedigree and credentials, judged solely on their competence. This new, globally connected, meritocracy is developing its own vocabulary and pastimes: even playing games with people around the world, and occasionally finding their true love before ever meeting in person.

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Contributor Post Created with Sketch. Saturday Night Science: Uncorking the Past

 

“Uncorking the Past” by Patrick E. McGovernWhile a variety of animals are attracted to and consume the alcohol in naturally fermented fruit, only humans have figured out how to promote the process, producing wine from fruit and beer from cereal crops. And they’ve been doing it since at least the Neolithic period: convincing evidence of a fermented beverage has been found in residues in pottery from the Jiahu site in China, inhabited between 7000 and 5800 B.C.

Indeed, almost every human culture which had access to fruits or grains which could be turned into an alcoholic beverage did so, and made the production and consumption of spirits an important part of their economic and spiritual life. (One puzzle is why the North American Indians, who lived among an abundance of fermentable crops never did—there are theories that tobacco and hallucinogenic mushrooms supplanted alcohol for shamanistic purposes, but basically nobody really knows.) What’s beyond doubt is that primates like their liquor: not only do monkeys and apes consume naturally fermented fruit, Malaysian tree shrews, closely related to primates, regularly binge on fermented pine nectar with around 3.8% alcohol.

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Contributor Post Created with Sketch. Saturday Night Science: Project Pluto

 
Project Pluto / SLAM nuclear ramjet cruise missile
Pluto/SLAM en route to target. Lawrence Livermore National Laboratory/Department of Energy artist’s conception, public domain.

In the 1950s and early 1960s, the development of controlled release of nuclear energy (as opposed to runaway reactions in nuclear weapons) seemed to make previously impossible things straightforward matters of engineering. On occasion, it made the unthinkable all too thinkable. Project Pluto, also known as the Supersonic Low Altitude Missile (SLAM), is one of the most extreme exemplars of this epoch. Unlike Project Orion, which envisioned a four thousand ton interplanetary spaceship powered by nuclear bombs, and Project Plowshare, which proposed using nuclear explosions for large civil engineering projects such as digging a new sea-level Panama canal, Pluto/SLAM (which I’ll henceforth refer to as Pluto) was developed and tested to the point where the technology had been proved. Pluto could have been deployed in the 1960s had the project not been cancelled due to financial reasons, competition from rival technologies, and people coming to their senses.

Pluto was a nuclear powered ramjet cruise missile, as large and heavy as a steam locomotive, which could fly between three and four times the speed of sound either at high altitudes or skimming the earth, with global range and the ability to stay airborne for months, and then to rain nuclear destruction upon multiple targets with high accuracy. Let’s unpack this description to understand just was was being developed.

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Contributor Post Created with Sketch. Saturday Night Science: Time in Powers of Ten

 

“Time in Powers of Ten” by Gerard 't Hooft and Stefan VandorenPhenomena in the universe take place over scales ranging from the unimaginably small to the breathtakingly large. The classic film, Powers of Ten, produced by Charles and Ray Eames, and the companion book explore the universe at length scales in powers of ten: from subatomic particles to the most distant visible galaxies. If we take the smallest meaningful distance to be the Planck length, around 10-35 metres, and the diameter of the observable universe as around 1027 metres, then the ratio of the largest to smallest distances which make sense to speak of is around 1062. Another way to express this is to answer the question, “How big is the universe in Planck lengths?” as “Mega, mega, yotta, yotta big!”

But length isn’t the only way to express the scale of the universe. In the present book, the authors examine the time intervals at which phenomena occur or recur. Starting with one second, they take steps of powers of ten (10, 100, 1000, 10000, etc.), arriving eventually at the distant future of the universe, after all the stars have burned out and even black holes begin to disappear. Then, in the second part of the volume, they begin at the Planck time, 5×10−44 seconds, the shortest unit of time about which we can speak with our present understanding of physics, and again progress by powers of ten until arriving back at an interval of one second.

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Contributor Post Created with Sketch. Saturday Night Science: The Perfect Machine

 

“The Perfect Machine” by Ronald FlorenceGeorge Ellery Hale was the son of a wealthy architect and engineer who made his fortune installing passenger elevators in the skyscrapers which began to define the skyline of Chicago as it rebuilt from the great fire of 1871. From early in his life, the young Hale was fascinated by astronomy, building his own telescope at age 14. Later he would study astronomy at MIT, the Harvard College Observatory, and in Berlin. Solar astronomy was his first interest, and he invented new instruments for observing the Sun and discovered the magnetic fields associated with sunspots.

His work led him into an academic career, culminating in his appointment as a full professor at the University of Chicago in 1897. He was co-founder and first editor of the Astrophysical Journal, published continuously since 1895. Hale’s greatest goal was to move astronomy from its largely dry concentration on cataloguing stars and measuring planetary positions into the new science of astrophysics: using observational techniques such as spectroscopy to study the composition of stars and nebulæ and, by comparing them, begin to deduce their origin, evolution, and the mechanisms that made them shine. His own work on solar astronomy pointed the way to this, but the Sun was just one star. Imagine how much more could be learned when the Sun was compared in detail to the myriad stars visible through a telescope.

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Contributor Post Created with Sketch. Saturday Night Science: Fashion, Faith, and Fantasy

 

“Fashion, Faith, and Fantasy” by Roger PenroseSir Roger Penrose is one of the most distinguished theoretical physicists and mathematicians working today. He is known for his work on general relativity, including the Penrose-Hawking Singularity Theorems, which were a central part of the renaissance of general relativity and the acceptance of the physical reality of black holes in the 1960s and 1970s. Penrose has contributed to cosmology, argued that consciousness is not a computational process, speculated that quantum mechanical processes are involved in consciousness, proposed experimental tests to determine whether gravitation is involved in the apparent mysteries of quantum mechanics, explored the extraordinarily special conditions which appear to have obtained at the time of the Big Bang and suggested a model which might explain them, and, in mathematics, discovered Penrose tiling, a non-periodic tessellation of the plane which exhibits five-fold symmetry, which was used (without his permission) in the design of toilet paper.

“Fashion, Faith, and Fantasy” seems an odd title for a book about the fundamental physics of the universe by one of the most eminent researchers in the field. But, as the author describes in mathematical detail (which some readers may find forbidding), these all-too-human characteristics play a part in what researchers may present to the public as a dispassionate, entirely rational, search for truth, unsullied by such enthusiasms. While researchers in fundamental physics are rarely blinded to experimental evidence by fashion, faith, and fantasy, their choice of areas to explore, willingness to pursue intellectual topics far from any mooring in experiment, tendency to indulge in flights of theoretical fancy (for which there is no direct evidence whatsoever and which may not be possible to test, even in principle) do, the author contends, affect the direction of research, to its detriment.

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Contributor Post Created with Sketch. Saturday Night Science: Idea Makers

 

“Idea Makers” by Stephen WolframI first met Stephen Wolfram in 1988. Within minutes, I knew I was in the presence of an extraordinary mind, combined with intellectual ambition the likes of which I had never before encountered. He explained that he was working on a system to automate much of the tedious work of mathematics—both pure and applied—with the goal of changing how science and mathematics were done forever. I not only thought that was ambitious; I thought it was crazy. But then Stephen went and launched Mathematica and, twenty-eight years and eleven major releases later, his goal has largely been achieved. At the centre of a vast ecosystem of add-ons developed by his company, Wolfram Research, and third parties, it has become one of the tools of choice for scientists, mathematicians, and engineers in numerous fields.

Unlike many people who founded software companies, Wolfram never took his company public nor sold an interest in it to a larger company. This has allowed him to maintain complete control over the architecture, strategy, and goals of the company and its products. After the success of Mathematica, many other people, and I, learned to listen when Stephen, in his soft-spoken way, proclaims what seems initially to be an outrageously ambitious goal. In the 1990s, he set to work to invent A New Kind of Science: the book was published in 2002, and shows how simple computational systems can produce the kind of complexity observed in nature, and how experimental exploration of computational spaces provides a new path to discovery unlike that of traditional mathematics and science. Then he said he was going to integrate all of the knowledge of science and technology into a “big data” language which would enable knowledge-based computing and the discovery of new facts and relationships by simple queries short enough to tweet. Wolfram Alpha was launched in 2009, and Wolfram Language in 2013. So when Stephen speaks of goals such as curating all of pure mathematics or discovering a simple computational model for fundamental physics, I take him seriously.

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Contributor Post Created with Sketch. Saturday Night Science: Into the Black

 

“Into the Black” by Rowland WhiteOn April 12, 1981, coincidentally exactly twenty years after Yuri Gagarin became the first man to orbit the Earth in Vostok 1, the United States launched one of the most ambitious and risky manned space flights ever attempted. The flight of Space Shuttle Orbiter Columbia on its first mission, STS-1, would be the first time a manned spacecraft was launched with a crew on its first flight. (All earlier spacecraft were tested in unmanned flights before putting a crew at risk.) It would also be the first manned spacecraft to be powered by solid rocket boosters which, once lit, could not be shut down but had to be allowed to burn out. In addition, it would be the first flight test of the new Space Shuttle Main Engines, the most advanced and high performance rocket engines ever built, which had a record of exploding when tested on the ground. The shuttle would be the first space vehicle to fly back from space using wings and control surfaces to steer to a pinpoint landing. Instead of a one-shot ablative heat shield, the shuttle was covered by fragile silica tiles and reinforced carbon-carbon composite to protect its aluminium structure from reentry heating which, without thermal protection, would melt it in seconds. When returning to Earth, the shuttle would have to maneuver in a hypersonic flight regime in which no vehicle had ever flown before, then transition to supersonic and finally subsonic flight before landing. The crew would not control the shuttle directly, but fly it through redundant flight control computers which had never been tested in flight. Although the orbiter was equipped with ejection seats for the first four test flights, they could only be used in a small part of the flight envelope: for most of the mission everything simply had to work correctly for the ship and crew to return safely. Main engine start—ignition of the solid rocket boosters—and liftoff!

Even before the goal of landing on the Moon had been accomplished, it was apparent to NASA management that no national consensus existed to continue funding a manned space program at the level of Apollo. Indeed, in 1966, NASA’s budget reached a peak which, as a fraction of the federal budget, has never been equalled. The Saturn V rocket was ideal for lunar landing missions, but expended each mission, was so expensive to build and operate as to be unaffordable for suggested follow-on missions. After building fifteen Saturn V flight vehicles, only thirteen of which ever flew, Saturn V production was curtailed. With the realisation that the “cost is no object” days of Apollo were at an end, NASA turned its priorities to reducing the cost of space flight, and returned to a concept envisioned by Wernher von Braun in the 1950s: a reusable space ship.

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Contributor Post Created with Sketch. Saturday Night Science: The Age of Em

 

“The Age of Em” by Robin HansonMany books, both fiction and nonfiction, have been devoted to the prospects for and consequences of the advent of artificial intelligence: machines with a general cognitive capacity which equals or exceeds that of humans. While machines have already surpassed the abilities of the best humans in certain narrow domains (for example, playing games such as chess or go), you can’t take a chess playing machine and expect it to be even marginally competent at a task as different as driving a car or writing a short summary of a newspaper story, things most humans can do with a little experience. A machine with “artificial general intelligence” (AGI) would be as adaptable as humans, and able with practice to master a wide variety of skills.

The usual scenario is that continued exponential progress in computing power and storage capacity, combined with better understanding of how the brain solves problems, will eventually reach a cross-over point where artificial intelligence matches human capability. But since electronic circuitry runs so much faster than the chemical signalling of the brain, even the first artificial intelligences will be able to work much faster than people, and, applying their talents to improving their own design at a rate much faster than human engineers can work, will result in an “intelligence explosion,” where the capability of machine intelligence runs away and rapidly approaches the physical limits of computation, far surpassing human cognition. Whether the thinking of these super-minds will be any more comprehensible to humans than quantum field theory is to a goldfish and whether humans will continue to have a place in this new world and, if so, what it may be, has been the point of departure for much speculation.

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Contributor Post Created with Sketch. Saturday Night Science: Proxima Centauri b

 
Artist's conception of the view from Proxima Centauri b
Artist’s impression of the view from Proxima Centauri b. Red dwarf Proxima is near the horizon, while distant Alpha Centauri A and B are above to the right. European Southern Observatory image licensed under the Creative Commons Attribution 4.0 International License.

On August 24, 2016, the European Southern Observatory (ESO) held a press conference at its headquarters near Munich, Germany to announce the discovery of a planet orbiting Proxima Centauri, the closest star to the Sun. Based upon the measured properties of the star and planet, the planet was believed to have a rocky surface (as opposed to being a ball of gas like the Sun’s outer planets), a mass just 30% greater than that of the Earth, and orbit within its star’s “habitable zone”: the band around the star at which, depending upon assumptions about its atmosphere, liquid water might exist on its surface. This was a stunning announcement, not only as a scientific achievement in being able to detect such a planet, but also knowing that the nearest star has a planet which is potentially habitable. (That’s “potentially”: there are many details which will be discussed below.) Recall that prior to 1992 we had not discovered a single planet outside the solar system, and although most astronomers suspected otherwise, it could be possible that the formation of planets like those which orbit the Sun was a freak process which occurred only rarely. Observations over subsequent decades have painted a picture of a universe with planets everywhere: we know of thousands of them now, and expect to find many more as increasingly powerful instruments are devoted to the search. Further, Proxima (I’ll address it informally from here on) is representative of stars that make up around three quarters of all those in the galaxy; if the closest such star has a habitable planet, imagine how many others there may be among the hundreds of billions of other stars like it.

The Nearest Stars

Alpha Centauri is the third-brightest star in the sky. Because it appears in the southern sky, at a declination of –60°, it is not visible to observers in the northern hemisphere unless they’re at 29° north latitude or farther south. From the southern hemisphere, Alpha Centauri is a brilliant beacon, and has been described since antiquity. To the unaided eye, it appears as a star of magnitude −0.27, but binoculars or a small telescope will reveal that it is actually a double star system, made up of two components: A, which is similar to our Sun but about 10% more massive, and B, a less massive and cooler star, with about 90% of the mass of the Sun. The two stars orbit one another with a period of 80 years, and as they move in their orbits the apparent separation as observed from Earth changes. Alpha Centauri has been known to be a double star since 1689, and astronomers have followed the motion of the two stars ever since.

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Contributor Post Created with Sketch. Saturday Night Science: Perseid Meteors, August 11–12

 

Perseid meteor, 2015-08-12Every mid-August, the Earth crosses the orbit of Comet 109/P Swift-Tuttle, and as debris from the comet enters the Earth’s atmosphere, meteors will be seen in the night sky with paths pointing back toward the comet’s orbit (the radiant of the meteor shower). As you might expect for the Perseids, this is in the constellation of Perseus which—for observers in temperate latitudes of the northern hemisphere, will be in the northeast sky in the evening hours, rising higher as the night progresses. Meteors can appear anywhere in the sky, but if you trace their paths back, they’ll converge at the radiant (with the exception of sporadic meteors which occur all the time and are unrelated to the meteor shower). You can produce a custom sky chart for your latitude, longitude, and observing time by using Your Sky to help locate Perseus.

The Perseid meteor shower was first recorded by a Chinese astronomer in 36 AD, and continues to put on a reliable show every year. The meteors hit the upper atmosphere with a mean velocity of 58 km/sec (almost eight times as fast as satellites in low Earth orbit), and you’ll occasionally see a fireball meteor as bright as the planet Venus. The picture above is a fireball I was lucky enough to photograph during the 2015 shower.

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Contributor Post Created with Sketch. Member Post

 

Saturday Night Science is on summer vacation until September, but I’ll occasionally post short notes on interesting things I come across in science and technology. This week’s is a Web site which uses deep learning technology to produce a full colour image from a monochrome image input. To use it, visit the site, enter the […]

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Contributor Post Created with Sketch. Saturday Night Science: Occultation of Aldebaran, July 29

 
Moon occults Aldebaran
Moon occults Aldebaran. Image by Wikipedia user Christina Irakleous used under the Creative Commons Attribution-Share Alike 4.0 International license.

If you’ve ever played with a telescope, you’ve doubtless noticed that regardless of how high a magnification you use, stars always appear as point sources. They’re so far away (see Saturday Night Science for July 2, “Parallax”) that even the largest telescopes cannot resolve their discs. (It is possible to measure the size of some stars by means of an interferometer, but such specialized equipment is rarely available to amateurs.)

On the morning of July 29, observers to the south of a diagonal line which crosses the North American continent southwest to northeast from El Paso to Montréal will have an opportunity to indirectly observe the disc of a star when the Moon passes in front of (occults) the bright orange giant star Aldebaran in the constellation of Taurus. In 1921, the angular diameter of this star was measured with an interferometer as 0.0237 arc seconds (or 23.7 milliarcseconds). This is the angle subtended by a US quarter dollar coin viewed from a distance of 211 km or 131 miles. But at the distance of the Moon, this angle corresponds to an object around 40 metres in size, comparable to the roughness of the Moon’s terrain.

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Contributor Post Created with Sketch. Saturday Night Science: Parallax

 

“Parallax” by Alan W. HirshfeldEppur si muove.” As legend has it, these words were uttered (or muttered) by Galileo after being forced to recant his belief that the Earth revolves around the Sun: “And yet it moves.” The idea of a heliocentric model, as opposed to the Earth being at the center of the universe (geocentric model), was hardly new: Aristarchus of Samos had proposed it in the third century B.C., as a simplification of the prevailing view that the Earth was fixed and all other heavenly bodies revolved around it. This seemed to defy common sense: if the Earth rotated on its axis every day, why weren’t there strong winds as the Earth’s surface moved through the air? If you threw a rock straight up in the air, why did it come straight down rather than being displaced by the Earth’s rotation while in flight? And if the Earth were offset from the center of the universe, why didn’t we observe more stars when looking toward it than away?

By Galileo’s time, many of these objections had been refuted, in part by his own work on the laws of motion, but the fact remained that there was precisely zero observational evidence that the Earth orbited the Sun. This was to remain the case for more than a century after Galileo, and millennia after Aristarchus, a scientific quest which ultimately provided the first glimpse of the breathtaking scale of the universe.

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Contributor Post Created with Sketch. Saturday Night Science: Slide Rule

 

Slide ruleBefore computers and calculators, there were slide rules. It is difficult for people today to appreciate just how magic it was to be able to carry a small tool, made of bamboo and plastic, that could perform many of the computations of engineering and science which used to be so tedious in mere seconds, as long as you were happy with its limited precision.

In my own years in engineering school, I did almost all of my homework and examination calculations with a slide rule and, when I graduated and was able to buy one of the first generation of pocket calculators (an HP-45), was amazed by its precision and ease of use, but had to admit that in practical work I could get the job done just about as fast with a slide rule.

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Contributor Post Created with Sketch. Saturday Night Science: The Frozen Water Trade

 

“The Frozen Water Trade” by Gavin WeightmanIn the summer of 1805, two brothers, Frederic and William Tudor, both living in the Boston area, came up with an idea for a new business which would surely make their fortune. Every winter, fresh water ponds in Massachusetts froze solid, often to a depth of a foot or more. Come spring, the ice would melt.

This cycle had repeated endlessly since before humans came to North America, unremarked upon by anybody. But the Tudor brothers, in the best spirit of Yankee ingenuity, looked upon the ice as an untapped and endlessly renewable natural resource. What if this commodity, considered worthless, could be cut from the ponds and rivers, stored in a way that would preserve it over the summer, and shipped to southern states and the West Indies, where plantation owners and prosperous city dwellers would pay a premium for this luxury in times of sweltering heat?

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Contributor Post Created with Sketch. Saturday Night Science: Humans to Mars

 

“Humans to Mars” by David S. F. PortreeEver since people began to think seriously about the prospects for space travel, visionaries have looked beyond the near-term prospects — flights into Earth orbit, space stations, and even journeys to the Moon — and toward the red planet: Mars. Unlike Venus, eternally shrouded by clouds, or the other planets which were too hot or cold to sustain life as we know it, Mars, about half the size of the Earth, had an atmosphere, a day just a little longer than the Earth’s, seasons, and polar caps which grew and shrank with the seasons. There were no oceans, but water from the polar caps might sustain life on the surface, and there are dark markings that appeared to change during the martian year. Some people interpreted this as plant life that flourished as polar caps melted in the spring and receded as they grew in the fall.

In an age where we have high-resolution imagery of the entire martian globe — obtained from orbiting spacecraft, telescopes orbiting Earth, and ground-based telescopes with advanced electronic instrumentation — it is often difficult to remember just how little was known about Mars in the 1950s, when people first started to think about how we might go there. Mars is the next planet outward from the Sun, so its distance and apparent size vary substantially depending upon its relative position to Earth in their respective orbits. About every two years, Earth “laps” Mars and it is closest (“at opposition”) and most easily observed. But because the orbit of Mars is elliptic, its distance varies from one opposition to the next, and it is only every 15 to 17 years that a near-simultaneous opposition and perihelion render Mars most accessible to Earth-based observation.

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