Some people hate on-demand electric scooters — and some people really hate them.

This guy in Florida falls into some third group positioned even further along that axis of disgruntlement. From the South Florida Sun-Sentinel:

A 59-year-old man who police say was caught in the act of vandalizing electric scooters — slicing the brake lines on as many as 140 — offered no motive during his arrest, a Fort Lauderdale police report said.

He also requested a lawyer and said he "did not want to dig himself into a grave," police said.

During the dark predawn hours, Randall Thomas Williams would set out with a single glove, wirecutters and pliers and, while sticking to the shadows and alleyways of his Las Olas neighborhood, search for the controversial, yet popular, rental scooters that have swarmed the city for nearly a year, police said.

He's been doing it since at least May, police said, and has vandalized at least 140 e-scooters in the same fashion, most within a two-block radius of Williams' apartment at the corner of Southeast First Street and Southeast 12th Avenue between Broward and Las Olas boulevards.

Apparently he was also placing stickers on the scooters' QR codes, to make them unrentable using the scooter-rental app. In the video above you can see him first ensticker the scooters, then come back to snip the brake cords.

These cute little pottery vessels — fashioned in the shape of animals — are about 3,000 years old, and were found near children's graves. A group of scientists hypothesized that they might actually be sippy cups, and when they analyzed the contents, voila: They contained the residue of milk. Sippy cups!

Over at Fast Company, Elizabeth Segran meditates on the design lessons at hand here. Quite apart from the fact that adorable animal-shapes clearly have a historic vintage in tech-for-feeding-children, our ancestors had a leg up on us in their use of sustainable materials:

These prehistoric sippy cups remind us that people were extremely creative with reusable materials millennia before plastic was invented. Just like our baby bottles, these ancient vessels were functional, perfectly sized for pouring milk into a child's small mouth. But they were also fun, shaped like tiny cows and goats. And unlike our plastic bottles, which are designed to be thrown out after a few years, it took time and effort to create these ancient vessels—it is likely they would have been designed to last, perhaps even passed down from one child to another. They were such valuable items, full of such sentimental value, that they were buried with children who died too soon.

The original academic letter, "Milk of ruminants in ceramic baby bottles from prehistoric child graves," is online and unpaywalled here.

(Image above from Enver Hirsch/courtesy Wien Museum])

Here's a video of an octopus changing color while it's asleep. Are the patterns in response to a dream?

Possibly, suspects the Alaska Pacific University professor David Scheel. That video is from an upcoming PBS TV show called "Octopus: Making Contact", and in it, Scheel narrates the color changes thusly:

"She's asleep; she sees a crab and her color starts to change a little bit. Then she turns all dark. Octopuses will do that when they leave the bottom.

"This is a camouflage, like she's just subdued a crab and now she's going to sit there and eat it and she doesn't want anyone to notice her. It's a very unusual behavior, to see the color come and go on her mantle like that. I mean, just to be able to see all the different color patterns just flashing one after another — you don't usually see that when an animal's sleeping. This really is fascinating."

The truth is, we don't actually know if cephalopods dream. There is some scant observational data, as this piece in Atlas Obscura noted a while ago:

The only cephalopod with a proven penchant for dreaming is probably the cutest. A 2012 study led by Marcos G. Frank, now a neuroscientist at Washington State University Health Sciences Spokane, discovered that sleeping cuttlefish demonstrate a form of rapid eye movement (REM), the same stage of sleep that gives us our dreams, distinguished by the spontaneous activation of brain cells, going off like fireflies in a forest. For a cephalopod, this manifests in frantic eye movements under closed lids (octopuses: they're just like us) or erratic shifts in skin coloration (or not). In Frank's study, the sleeping cuttlefish's chromatophores recombined into recognizable patterns, just like ones they displayed while awake. He believes this might be analogous to the weirdly familiar patchwork of human dreams. "This video is the best evidence I have ever seen that this particular cephalopod has a sleep-state similar to what we saw in cuttlefish," Frank says of the Caribbean two-spot octopus.

(Thanks to Susan Glickman and Harry Allen for pointing out this one!)

A new analysis of whales suggests that each one is worth about $2 million in carbon sequestration — and the global population is thus worth about $1 trillion.

How do whales sequester carbon? By eating stuff, getting big, then drifting to the bottom of the ocean after they die. This makes them carbon sinks on a scale even bigger than most trees, as the authors point out:

The carbon capture potential of whales is truly startling. Whales accumulate carbon in their bodies during their long lives. When they die, they sink to the bottom of the ocean; each great whale sequesters 33 tons of CO2 on average, taking that carbon out of the atmosphere for centuries. A tree, meanwhile, absorbs only up to 48 pounds of CO2 a year.

On top of that, the metabolic activity of whales — their breathing, peeing and pooping — stimulates huge growths of phyloplankton, which itself sequesters tons of carbon. As National Geographic notes, in a post about this new study …

When phytoplankton die, much of their carbon gets recycled at the ocean's surface. But some dead phytoplankton inevitably sink, sending more captured carbon to the bottom of the sea. Another study from 2010 found that the 12,000 sperm whales in the Southern Ocean draw 200,000 tons of carbon out of the atmosphere each year by stimulating phytoplankton growth and death through their iron-rich defecations.

When the study authors priced out the cost of carbon capture, that's how they arrived at the value of $2 million per whale.

The corollary of this analysis is that if we could increase protections for whales — and expand their population — it could sequester even more carbon. As Nat Geo notes …

There are about 1.3 million great whales in Earth's oceans today. If we could restore them to their pre-commercial whaling numbers—estimated at between 4 and 5 million— the economists' calculations show that great whales could capture about 1.7 billion tons of carbon dioxide each year. That's more than the annual carbon emissions of Brazil.

It's worth keeping this in perspective, though, because while that's a lot of carbon, there's a lot more to sequester. This new analysis is more about reframing the way we ponder the value of natural systems to global survival and flourishing:

However, it's only a few percent of the 40 billion tons of carbon dioxide humanity spews into the air each year. And even with aggressive global conservation efforts, it could be decades before great whales rebound to their pre-whaling numbers, assuming that's possible at all given how much we've degraded the oceans.

"We don't want to oversell the concept," said Steven Lutz, the Blue Carbon Program Leader at GRID-Arendal, a Norweigan foundation that works with the United Nations Environment Program. "It's not like we save the whales and we save the climate."

To Lutz, the exact numbers presented in the new analysis are less significant than the framework it introduces for thinking about wild animals in terms of their value when kept alive. He'd like to see this sort of approach applied to carbon-rich marine ecosystems like seagrass beds, and to other groups of marine organisms, like fish.

The original analysis has some terrific infographics that neatly illustrate the role of whales in carbon sequestration, including this one here …

(CC-2.0-licensed photo of a whale courtesy the Flickr stream of Christopher Michel)

The folks at JSTOR Daily have unearthed the proceedings of a 1953 colloquium that pondered a great question: Did early humanity first cultivate grain not for the purpose of making bread — but brewing beer? Or, as official title of the event asked, "Did Man Once Live By Beer Alone?"

If the latter is true, then we owe the very concept of agriculture to the delights of getting sozzled.

As the proponents of that theory noted, beer-like drinks are arguably easier to create than bread. The former requires less technology:

The proponents of the beer-before-bread idea noted that the earliest grains might have actually been more suitable for brewing than for baking. For example, some wild wheat and barley varieties had husks or chaff stuck to the grains. Without additional processing, such husk-enclosed grains were useless for making bread—but fit for brewing. Brewing fermented drinks may also have been easier than baking. Making bread is a fairly complex operation that necessitates milling grains and making dough, which in the case of leavened bread requires yeast. It also requires fire and ovens, or heated stones at the least.

On the other hand, as some attendees pointed out, brewing needs only a simple receptacle in which grain can ferment, a chemical reaction that can be easily started in three different ways. Sprouting grain produces its own fermentation enzyme—diastase. There are also various types of yeast naturally present in the environment. Lastly, human saliva also contains fermentation enzymes, which could have started a brewing process in a partially chewed up grain. South American tribes make corn beer called chicha, as well as other fermented beverages, by chewing the seeds, roots, or flour to initiate the brewing process.

The problem with the Beer Hypothesis, as I'm calling it, is that it's not clear whether it'd have made for a diet that was solid enough. One participant had some choice words on the subject:

"Man cannot live on beer alone, and not too satisfactorily on beer and meat," noted botanist and agronomist Paul Christoph Mangelsdorf. "And the addition of a few legumes, the wild peas and lentils of the Near East, would not have improved the situation appreciably. Additional carbohydrates were needed to balance the diet… Did these Neolithic farmers forego the extraordinary food values of the cereals in favor of alcohol, for which they had no physiological need?" He finished his statement with an even more provoking inquiry. "Are we to believe that the foundations of Western Civilization were laid by an ill-fed people living in a perpetual state of partial intoxication?"

I dunno — if the foundations of western civilization "were laid by an ill-fed people living in a perpetual state of partial intoxication", that seems like it would explain quite a lot really.

(CC-2.0-licensed photo of beer courtesy the Flickr stream of Alan Levine)

Christopher Herwig is a photographer who previously did a fantastic series of photos of Soviet-era bus stops.

Now he's back with a book of photos of Soviet subway stops — and they are, if anything, even more mesmerizingly gorgeous. The USSR really went in for epic geometric patterns receding into the infinite distance. The book's available here, and his Instagram is here.

Some more photos of stops are below, but here's a bit from a Colossal post talking about how he got exposed to the subject:

Herwig explains that he became interested in the underground architecture of the stations while visiting Moscow and Tashkent. Because many of the metro stations were used as nuclear bomb shelters, they were considered military sites and photographing them was prohibited. "Although I likely could have gotten away with a few images I really wanted to do the series properly and cover all the cities in the former USSR with metro lines not just a few flashy ones in Moscow," he told Colossal. "With restriction being lifted in many of the cities it meant I could have a go at it."

Herwig's images take viewers on a journey through the architectural and political influences of decades pasts. Soviet-era symbols, relief sculptures of significant events and figures, and displays of opulence cover every square meter of the well-maintained subterranean spaces. Often making early morning and late night trips into the stations, Herwig says that many of the otherwise busy hubs appear to be abandoned because of his goal to "use people with purpose and not to distract from the space and design of the stations."

The pix …

(Photos used here by permission of Christopher Herwig / FUEL)

Maybe you've seen the video that's gone viral on Twitter of a helicopter trimming the trees in a forest by dangling a massive chainsaw that's composed of ten spinning blades?

If not, maybe take a minute to check it out; it is probably impossible to be disappointed by that minute of your life.

Anyway, helicopter chainsaw-ing has been going on for some years; it's often used to efficiently trim greenery that's growing too close to power lines. Popular Mechanics hunted down a company that offers it as a service and got the 411 on what it's like to pilot one of these dread mechanisms:

The 2-foot diameter blades turn at 4,000 rpm and are powered by a 28-horsepower engine controlled by the pilot, according to T&D World. It's challenging work, but plenty of additional safety measures are in place. If a saw catches on a branch, for instance, the pilot can release the entire saw and fly off.

As you'd expect, it takes a lot of training to wield this wily air saw. The more than 30 Aerial Solutions pilots who conduct this work must have over 1,000 flying hours, and a dedicated crew of mechanics is tasked with maintaining the choppers. "One of the things that we focus on—and this was part of William Cox and the Rogers Family's agreement—is to make sure that we have a safe operation," Aerial Solutions Inc.'s general manager Ted McAllister tells Popular Mechanics.

The air saw is best used in inaccessible mountainous regions and in tight spots, such as between a pipeline or power lines and the surrounding forest. Aerial Solutions dispatches a crew of two people—the pilot and a ground crewman—and argues that this method is a safer alternative to sending out hand crews who may spend days or weeks hoisted in buckets or hanging from branches.

Sharks with frickin' laser beams :: helicopters with chainsaws.

Over at Hackaday, the user sjm4306 has posted some pretty cool projects in the past, including a Nixie-tube clock and a tiny IV-21 VFD clock.

Now he's created something else delightful — a little clock that uses LEDs to spell out the time by backlighting cut-out words. I've seen lots of word clocks but never one with such an elegant little form factor.

He worked neatly with some design constraints too, as Hackaday notes:

One design challenge for the letter matrix was fitting all possible minutes into the array. Rather than making a larger array of letters, [sjm4306] had the clock describe the time down to five-minute intervals then add asterisks for the full time. It's a pretty understandable solution for keeping the design simple, and the letters all fit onto the design so well!

Here's his design video …

… and some more pix of the finished clock:

Maybe you've heard the famous story of the Inuit elder who, when his family takes away his tools to keep him from living out on the ice, makes a knife out of his own frozen poop.

The story was first popularized by anthropologist Wade Davis in a 1998 book, and even back then, even Davis admitted it miiiiiiiight be apocryphal. But the story has been repeated so often and so breathlessly that finally two anthropologists — Metin Eren and Michelle Bebber of Kent State — decided to test it.

So they collected their poop for several days and used it to make knifes. As Jennifer Ouellette writes in Ars Technica …

"It's funny, because we've got this amazing lab," said Eren, but for that week, "I'm not in the lab—I'm in my house pooping in a bag, making knives out of my own feces. It was sort of depressing."

They crafted the fecal knives using ceramic molds or simply using their hands to mold the feces into a rudimentary blade before sharpening them with a metal file after they were frozen solid. Then it was time to test them.

There was no need to actually butcher a dog. Eren and Bebber used pig hide—cold and hairless—muscle, and tendons. The meat they used had been refrigerated, unlike a fresh kill, which would have been warm, and the knives were chilled in dry ice to -50 C (-58 F) prior to cutting. "We really wanted to give our knives the best possible chance to succeed," said Eren.

Unfortunately, even under these ideal lab conditions, none of the molded or hand-shaped fecal knives made from either scientist's feces succeeded in cutting through the hide. The knives simply melted upon contact, leaving behind brown streaks (skid marks) of melted poop. They did manage to make shallow slices on the subcutaneous fat on the underside of the hide, but the knife-edge still melted quickly and became unusable.

"I was amazed that human feces could get as hard as they do when frozen," Eren said. "So I was thinking to myself, 'My god, this may actually work.' That made it all the more disheartening when we did the test."

As they point out, they did their experiment in a room chilled to minus 50 degrees C, so it's possible that if you went even colder, poop knives might work.

The scientists' paper — with the immortal title "Experimental replication shows knives manufactured from frozen human feces do not work" — is online here unpaywalled.

Recently a team of marine scientists were piloting a submersible when they had a super-rare encounter with a Deepstaria jellyfish. It starts off looking like a ghost and then turns inside out and spreads out into a crazy translucent film.

It's gorgeous and eerie to watch, but make sure you turn the sound up — the real fun is listening to the scientists talk. Half the time they're discussing the biology of the creature, and the other half they're just going whoooooah and oooooooooo and zooooommgg, so the whole event exists in the rapid quantum flipzone between "hardcore science" and "baked dormroom conversation".

I would totally watch a 24/7 network that consisted of nothing but marine biologists flipping out while watching crazy undersea footage.

From Popular Science:

Deepstaria is as mysterious as it is rare, a shapeshifter whose body exists somewhere on a spectrum between enormous trash bag and ghostly lampshade. Last week, these researchers used a remotely operated vehicle to capture a video of the freaky jelly.

The jellyfish in the video is roughly the size of a trash can. This deep-sea jelly lacks tentacles, and appears in the shape of a thin, membrane-like bell. Up close, you can see a geometric mesh pattern made up of canals that provide structural support and deliver nutrients to the body. In 2015, Wired referred to it as a "floating blanket." [snip]

The team watches as the animal swoops, undulates and puckers like a possessed plastic bag. But this mesmerizing movement isn't what makes the video so valuable for scientists.

This video represents the rare instance of observing the jellyfish in its natural, undisturbed state, says Brennan Phillips, an engineer who has worked on prior Nautilus expeditions. Normally (99.9% of the time, according to Phillips) Deepstaria is shaped like an upside-down bucket, just hanging out trying to catch prey (this is the shape it appears in during the first 40 seconds of the video).

Daniel Colin James thinks it's time to get rid of the CAPS LOCK key on physical keyboards.

Why? Partly because it's a relic of history, created in the 60s by the Bell Labs engineer Doug Kerr, who noticed that people often wanted to type street addresses in all caps — but there was no key in existence that would capitalize letters but not numbers.

Colin James actually called up Kerr, who's still around, to get the story, which is quite interesting. As Colin James writes on Medium …

The QWERTY keyboard debuted in 1873 on a typewriter that could only produce capital letters. A few years later came the Shift key, which toggled the typewriter's output between lowercase and uppercase letters.

The Shift key physically shifted the internals of the typewriter, so it took some effort to press it down. Eventually, a Shift Lock key was created to hold it down. With Shift Lock engaged, letter keys produced their uppercase counterparts, but number keys produced symbols. That was a problem.

Doug Kerr was a telephone engineer working at Bell Labs in the 1960s. He watched his boss's secretary repeatedly get frustrated after accidentally typing things like "$%^&" instead of "4567" in addresses because of Shift Lock.

So he did something about it. Doug Kerr invented the "CAP" key. CAP performed the same function as Shift Lock, except it only affected the letter keys.

"CAP" became Caps Lock, which made its way onto the computer keyboard, where it has remained part of the standard layout ever since.

So it's a historic relic that, Colin James argues, just eats up space on a physical keyboard. Why not have CAPS LOCK engaged the way it is on smartphone keyboards — i.e. with a double-tap on the SHIFT key — and free up the CAPS LOCK key to toggle on something more useful, like emoji?

Apparently even Kerr agrees it's time for the physical key to go.

I'm down. Though I gently diverge from Colin James' argument that "most of us don't often have a reason to type anything in all caps today," given that we have bold and italics. I frequently use all caps on Twitter, since it's the best way to indicate that you are well and truly hollering something at the top of your lungs for emphasis. And isn't that like TOTALLY TWITTER amirite

Almost as much as is the art of ending a sentence without punctuation

Which, contextually, doesn't work as well on blog posts does it

(CC-2.0-licensed photo of the CAPS LOCK key courtesy the Flickr feed of i_yudai)

University of Cambridge lecturer Jason Scott-Warren was looking at an original 1623 folio copy of Shakespeare's plays, when thought he recognized the handwriting in the margins: John Milton.

Was it possible that he'd identified Milton's personal copy of Shakespeare? It was jammed full of marginalia, and scholars for years had wondered who had written those scribblings. If it was Milton, then they had a record "of arguably the second-greatest 17th-century writer reading the first."

So Scott-Warren went to his blog and wrote a post arguing his hypothesis, hit "publish" — and the world of 17th-century English literary studies went faintly nuts. Turns out they agreed with him and now they're all flipping out with excitement.

One of the best parts about Milton's notes is that he keeps on suggesting corrections and improvements to Shakespeare. As the Washington Post writes (my apologies if this is paywalled):

Milton's marginalia range from line-editing — crossing out an adjective and offering an alternative — to flagging preferred passages to fixing Shakespeare's meter, ensuring it conforms perfectly to the rules of iambic pentameter. At one point, Milton rewrites the title of what may be Shakespeare's most famous work: The play becomes "Juliet and Romeo," not vice versa. [snip]

Bourne came to cherish particular edits. For example, the time the commenter suggested "wicked tongue" instead of "idle tongue" in Hamlet. Or the time he proposed that Juliet was "past hope, past cure, past help" instead of "past hope, past care, past help" in "Romeo and Juliet." [snip]

It's unclear why Milton may have made the marginalia and revisions. But — despite the man's well-documented massive ego — Scott-Warren, Bourne and experts cautioned against the idea that Milton saw himself as a superior writer entitled to edit Shakespeare.

It was more likely that Milton saw himself as correcting others' errors — saving Shakespeare, who died seven years before the folio appeared, from the printer, according to Scott-Warren.

"I don't think it's about wanting to do it better than Shakespeare; I think it's about appreciating the immense potential of the texts," Scott-Warren said. "Milton is a real admirer of Shakespeare. He thinks Shakespeare is a brilliant writer, and he wants the text to be as brilliant as it can be."

The Guardian also has a good story on this, and the post at the Intelligencer is probably the funniest on the subject.

First it was vinyl, then it was cassette tapes — now the latest old media that's being praised for offering warmer, richer, higher-quality experiences? (more…)

Back in 1970, Max Peintner drew a picture — "The Unending Attraction of Nature" — showing a stadium full of people all watching a forest of trees down on the field.

This year the Swiss curator Klaus Littman decided to make it a reality. He took 300 mature trees, some weighing up to six tons, and planted them in Austria's Wörthersee Stadium, turning it into a massive art project. Much like the original Peintner drawing, it's a haunting meditation on our relationship to nature, made additionally resonant given the today's depredations of climate change.

Of course, because it's about climate change, the reactionary right is pitching a hissy fit about the art. As Artnet reports:

Two hard right parties, the Alliance for the Future of Austria (BZÖ) and the Austrian Freedom Party (FPÖ), have publicly criticized the project, which is the brainchild of Swiss curator Klaus Littmann. Among other things, they have falsely claimed that the installation, which fills a local soccer stadium with a grove of 300 trees, was taxpayer-funded.

The resulting public controversy has taken on alarming dimensions. In a recent profile in Der Standard, Littmann claimed that he has not only faced verbal criticism for the project, but was also physically attacked on the street and pushed into traffic. According to the curator, his assailant shouted, "Go away and take your shitty forest!" ("Verschwind mit deinem Scheißwald!")

Before the September 8 opening, the BZÖ rallied supporters on social media, instructing them to gather in front of the stadium during Littmann's opening and make a statement with "non-functional chainsaws." In the end, the debut was a largely celebratory occasion, but as a result of the furor the stadium is now being guarded day and night, according to Deutsche Welle.

"I had not previously experienced such reactions," the curator told the publication. "Meanwhile people have come to thank me and talk about the project. The reactions are still bitter on social media though, where it's obviously easier to lash out."

It's a truly gorgeous work of art — I wish I could see in person myself. The official web site has some great pix (one of them below), and it also curates some wonderful ones posted by visitors on Instagram; worth checking out!

Earlier this summer I stopped by the office of Joel Spolsky, CEO of Stack Overflow, the mammoth forum for software developers, to talk about my new book Coders, which is all about the subculture of programmers and their impact on reality. (And which you can acquire right here folks, step right up.)

We were supposed to talk about coding but at first got totally sidetracked when I noticed Joel had a huge archive of issues of OMNI, so we spent 15 minutes excitedly babbling about the role that magazine played in our nerd youths. (They even hunted down some of the original ads for Heathkit robots.)

When we finally got around to talking about the culture of software creation, it was pretty fun, and they transcribed parts of our talk. Here's Joel talking about how he originally got into coding:

Clive: What was your original pathway into coding?

Joel: My parents were professors at the University of New Mexico, and the University bought a mainframe and didn't know what do with it. They gave every professor an account. And the professors gave those to their kids.

So I was part of a group of teenage kids just hanging around the computer center trying to figure stuff out.

Clive: So what was it, FORTRAN?

Joel: It had an interactive operating system because those had gotten trendy at universities. They had an interactive terminal system that had BASIC, FORTRAN, and PL1. Many, many years later I realized there was no way they had enough memory for three compilers and in fact what they had was a very simple pre-processsor that made Basic, Fortan, and PL1 all look like the same mush. It was a very crappy subset of each of those three languages.

Clive: Oh my god, that's trippy. For me, it was the generation of BASIC computers you could plug into a TV, that's what got me in. But also, hilariously, my high school in Toronto had set up a computer programming course you could take in your fourth year, where we learned FORTAN on punchcards. You fed them in and came back two hours later for them. I'm glad to have done it, because when I interview coders in their 70s and 80s, we can bond over tripping while walking down the hallway carrying a stack of 100 cards you forgot to number.

True story, that latter one. In my high school I took the single class they offered in computer programming, which for me was 1986. I and my friends had already been programming for years in BASIC, so we showed up thinking that we'd learn that, or maybe Pascal or Assembly.

Nope. It turns out that some years previously — likely, a decade previously — they'd signed up for an agreement to use a semi-decommissioned PDP-somethingorother parked in the basement of the University of Toronto, on a timeshare basis, to teach us FORTRAN on punchcards, batch-style. We were kind of baffled; by the mid-80s, punchcards seemed pretty retro, since realtime coding on a screen seemed the Way of the Future. But like I said in the interview, I'm now glad I got a chance to try my hand at that craft.

I've occasionally toyed with the idea building a punchcard reader for programming Javascript, just because why not. Maybe some weekend I'll roll up my sleeves and do it.

In 2012, James Cameron went in a submarine down to the floor of the Mariana Trench, one of the deepest parts of the world's oceans. He says he dove down 10,908 meters. Last May, Victor Vescovo went down into the Trench — and reached 10,924, precisely 16 meters deeper.

But as Matt Simon writes in Wired, precision is incredibly hard to measure in waters that deep — so there's still quite an argument about who went deeper.

Why is it hard to measure things down that far? Well …

… if you wanted, you could drop a 11,000-meter-long cable down into the Challenger Deep and measure depth that way, but the thing will be buffeted by 7 miles of currents, obliterating any pursuit of accuracy.

Instead, scientists and explorers typically rely on sound or pressure to measure depth, or both. Pressure, of course, increases as you go deeper. "Pressure is probably the best way to get an absolute measure of depth," says Mark Zumberge, a research geophysicist at the Scripps Institution of Oceanography. But that alone won't suffice, because water pressure can fluctuate as you descend—it depends in part on the water's density, which changes up and down the water column based on temperature and salinity.

"To convert pressure to depth, you need to know the water density over the full water column and also the local value of gravity, which varies by about half a percent over the surface of the Earth," Zumberge says. And if you're trying to be really precise, it's worth noting that gravity "even varies by a couple hundredths of a percent from the sea surface to the bottom of the ocean."

The other way to measure depth is using sonar, but that comes with its own complications. The idea is to ping the sea floor with sound and time how long it takes for the signal to get back to your boat. You have to know the temperature along the path to get an accurate reading, because sound travels faster through warmer water. Plus, if the sea floor is covered in sediment, as with the Challenger Deep, the ping might pierce that muck and end up bouncing off rock.

Given the bragging rights that come with being the deepest diver ever, I'm looking forward to seeing how this one shakes out.

(CC-2.0-licensed photo of James Cameron courtesy the Flickr feed of Gage Skidmore)