It’s Critical: Don’t Pile Up Your Fissionable Material

December 12, 2024 by Lewin Day 38 Comments

Nuclear fission is a powerful phenomenon. When the conditions are right, atomic nuclei split, releasing neutrons that then split other nuclei in an ongoing chain reaction that releases enormous amounts of energy. This is how nuclear weapons work. In a more stable and controlled fashion, it’s how our nuclear reactors work too.

However, these chain reactions can also happen accidentally—with terrifying results. Though rare, criticality incidents – events where an accidental self-sustaining nuclear chain reaction occurs – serve as sobering reminders of the immense and unwieldy forces we attempt to harness when playing with nuclear materials.

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Retrotechtacular: 1980s Restoration Of San Francisco’s Cable Car System

December 11, 2024 by Maya Posch 44 Comments

The cable car system of San Francisco is the last manually operated cable car system in the world, with three of the original twenty-three lines still operating today. With these systems being installed between 1873 and 1890, they were due major maintenance and upgrades by the time the 1980s and with it their 100th year of operation rolled around. This rebuilding and upgrading process was recorded in a documentary by a local SF television station, which makes for some fascinating viewing.

San Francisco cable car making its way through traffic. Early 20th century.

While the cars themselves were fairly straight-forward to restore, and the original grips that’d latch onto the cable didn’t need any changes. But there were upgrades to the lubrication used (originally pine tar), and the powerhouse (the ‘barn’) was completely gutted and rebuilt.

As opposed to a funicular system where the cars are permanently attached to the cable, a cable car system features a constantly moving cable that the cars can grip onto at will, with most of the wear and tear on the grip dies. Despite researchers at San Francisco State University (SFSU) investigating alternatives, the original metal grip dies were left in place, despite their 4-day replacement schedule.

Ultimately, the rails and related guides were all ripped out and replaced with new ones, with the rails thermite-welded in place, and the cars largely rebuilt from scratch. Although new technologies were used where available, the goal was to keep the look as close as possible to what it looked at the dawn of the 20th century. While more expensive than demolishing and scrapping the original buildings and rolling stock, this helped to keep the look that has made it a historical symbol when the upgraded system rolled back into action on June 21, 1984.

Decades later, this rebuilt cable car system is still running as smoothly as ever, thanks to these efforts. Although SF’s cable car system is reportedly mostly used by tourists, the technology has seen somewhat of a resurgence. Amidst a number of funicular systems, a true new cable car system can be found in the form of e.g. the MiniMetro system which fills the automated people mover niche.

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The Hovercraft Revolution And Finding The Right Niche For A Technology

December 11, 2024 by Maya Posch 39 Comments

In the world of transportation, some technologies may seem to make everything else appear obsolete, whether it concerns airplanes, magnetic levitation or propelling vehicles and craft over a cushion of air. This too seemed to be the case with hovercraft when they exploded onto the scene in the 1950s and 1960s, seemingly providing the ideal solution for both commercial and military applications. Freed from the hindrances of needing a solid surface to travel upon, or a deep enough body of water to rest in, hovercraft gave all the impressions of combining the advantages of aircraft, ships and wheeled vehicles.

Yet even though for decades massive passenger and car-carrying hovercraft roared across busy waterways like the Channel between England & mainland Europe, they would quietly vanish again, along with their main competition in the form of super fast passenger catamarans. Along the English Channel the construction of the Channel Tunnel was a major factor here, along with economical considerations that meant a return to conventional ferries. Yet even though one might think that the age of hovercraft has ended before it ever truly began, the truth may be that hovercraft merely had to find its right niches after a boisterous youth.

An example of this can be found in a recent BBC article, which covers the British Griffon Hoverwork company, which notes more interest in new hovercraft than ever, as well as the continued military interest, and from rescue workers.

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Disc Film,When Kodak Pushed Convenience Too Far

December 10, 2024 by Jenny List 42 Comments

Having a penchant for cheap second-hand cameras can lead to all manner of interesting equipment. You never know what the next second-hand store will provide, and thus everything from good quality rangefinders an SLRs to handheld snapshot cameras can be yours for what is often a very acceptable price. Most old cameras can use modern film in some way, wither directly or through some manner of adapter, but there is one format that has no modern equivalent and for which refilling a cartridge might be difficult. I’m talking about Kodak’s Disc, the super-compact and convenient snapshot cameras which were their Next Big Thing in the early 1980s. In finding out its history and ultimate fate, I’m surprised to find that it introduced some photographic technologies we all still use today.

Easy Photography For The 1980s

Since their inception, Kodak specialised in easy-to-use consumer cameras and films. While almost all the film formats you can think of were created by the company, their quest was always for a super-convenient product which didn’t require any fiddling about to take photographs. By the 1960s this had given us all-in-one cartridge films and cameras such as the Instamatic series, but their enclosed rolls of conventional film made them bulkier than required. The new camera and film system for the 1980s would replace roll film entirely, replacing it with a disc of film that would be rotated between shots to line up the lens on an new unexposed part of its surface. Thus the film cartridge would be compact and thinner than any other, and the cameras could be smaller, thinner, and lighter too. The Disc format was launched in 1982, and the glossy TV adverts extolled both the svelteness of the cameras and the advanced technology they contained. Continue reading “Disc Film,When Kodak Pushed Convenience Too Far” →

Unconventional Oil Production, All You Need To Know

December 5, 2024 by Jenny List 48 Comments

It’s fair to say that climate change is perhaps the greatest challenge facing our planet, and while much attention is directed towards solutions to the problems it presents, perhaps there’s less attention given to the the other side of the equation in the hydrocarbon industry. For example we all think we know something about hydraulic fracking wells, but how much do we really know?

[John Thurmond] is a geologist who has recently completed a long career in the oil industry, and he gave an informative talk on the matter at the summer’s EMF Camp in the UK. It makes for an interesting watch, as he leads the viewer through the process in detail, before discussing what should and shouldn’t cause worry.

We learn that fracking has two parts: first the hydraulic fracking itself, and then the re-injection of the toxic fracking well water released from underground along with the oil or gas. It seems the water released from the rocks a 10,000 ft depth contains all manner of toxic and even radioactive compounds, and the usual means of disposal is to inject it back into the ground at a much lower depth. He makes the point that while the hazards associated with the fracking are low, those of the re-injection are high.

The talk finishes up with perhaps the most interesting point, by looking at the nature of opposition to fracking, or indeed any other controversial development. Such things are inevitably surrounded by a swirling mess of half-truths, and his point is that identifying those easily deflected as not true is key to understanding the whole thing. It’s presented from an expert and factual perspective that’s so often lacking in this arena, and thus we think it’s worth a watch.

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A Brief History Of Teleportation

December 5, 2024 by Al Williams 85 Comments

OK, I know. We don’t have practical teleportation. But that hasn’t stopped generations of science fiction authors and movie makers from building stories around it. If you ask most ordinary people, they’d tell you the idea originated with the Star Trek transporter, but that’s far from the truth. So when did people start thinking about teleporting?

Ground Rules

Maybe it isn’t fair, but I will draw the line at magic or unexplained teleportation. So “The Tempest”, for example, doesn’t use technology but magic. To get to Barsoom, John Carter wished or slept to teleport to Mars. So, while technology might seem like magic, we’re focusing on stories where some kind of machine can send something — usually people — to somewhere else.

Of course, there’s a fine line between pure magic and pure technology where they overlap. For example, in the opera “Der Ring des Nibelungen”, a magic helmet gives people powers, including that of teleportation. While you could argue that Tarnhelm — the name of the magic helmet — was a technological artifact, it is still explained by magic, not science.

Some systems need a transmitter and a receiver. Sometimes, you only need the transmitter. Sometimes, you can only teleport within a limited range, but other make-believe systems can transport an entire starship across the galaxy.

Early Teleporters

The Man without a Body is a story from 1877 in which a scientist is able to transmit a cat via a telegraph wire. Encouraged, he attempts the same feat with himself, but the battery dies in the middle, leaving him with a disembodied head. The ending is decidedly devoid of science, but the story is possibly the earliest one with a machine sending matter across a distance.

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The London Underground Is Too Hot, But It’s Not An Easy Fix

December 4, 2024 by Lewin Day 89 Comments

The London Underground is an iconic piece of Victorian era engineering. What started in 1863 quickly became a core piece of infrastructure that would define the modern character of the British capital. It’s grown and changed immensely in the many years that have passed. Sadly, increasing patronage and more trains have created problems that the original designers never envisaged.

Deep in those London tunnels lies an engineering challenge. The Tube is literally cooking itself. Every day, millions of commuters descend into a network of tunnels that have been absorbing heat since the reign of Queen Victoria. Those clay-lined tubes have been soaking up excess thermal energy like a giant underground radiator, and now they’re giving it back with interest. The tunnels are simply too hot, and cooling them down is inordinately difficult.

The Perfect Storm of Thermal Chaos

The Tube’s heat problem isn’t just about one thing gone wrong – it’s about everything gone wrong at once. When Victorian engineers designed these tunnels, cooling wasn’t a major consideration. The tight, compact tunnels were built deep, nestled in the clay beneath London. In the early days, temperatures in the Underground were considered comfortably low.

“The Underground’s the only spot for comfort when the days are hot; it is cooler below.” – London Underground poster, 1926

Originally, the clay surrounding the tunnels sat at around 14°C, acting as a heat sink for the network. However, over the years, with more trains coming and going and more heat pouring in, the temperature has risen. It now typically sits anywhere from 19° to 26 °C. That’s just the earth around the tunnels, though. Air temperatures are worse—hitting as high as 47°C during a 2006 heatwave. The problem has been a continual bugbear of the beloved Tube, with concerns that future heatwaves could see temperatures rise ever higher. Continue reading “The London Underground Is Too Hot, But It’s Not An Easy Fix” →