Why Are Bots Unable to Check "I Am Not a Robot" Checkboxes?

iStock.com/Oleksandr Hruts
iStock.com/Oleksandr Hruts

Oliver Emberton:

How complicated can one little checkbox be? You can't even imagine!

For starters, Google invented an entire virtual machine—essentially a simulated computer inside a computer—just to run that checkbox.

That virtual machine uses Google's own language, which they then encrypt. Twice.

But this is no simple encryption. Normally, when you password protect something, you might use a key to decode it. Google’s invented language is decoded with a key that is changed by the process of reading the language, and the language also changes as it is read.

Google combines (or hashes) that key with the web address you’re visiting, so you can’t use a CAPTCHA from one website to bypass another. It further combines that with “fingerprints” from your browser, catching microscopic variations in your computer that a bot would struggle to replicate (such as CSS rules).

All of this is done just to make it hard for you to understand what Google is even doing. You need to write tools just to analyze it. (Fortunately people did just that).

It turns out that these checkboxes record and analyze a lot of data, including: Your computer’s timezone and time; your IP address and rough location; your screen size and resolution; the browser you’re using; the plugins you’re using; how long the page took to display; how many key presses, mouse clicks, and tap/scrolls were made; and ... some other stuff we don’t quite understand.

We also know that these boxes ask your browser to draw an invisible image [PDF] and send it to Google for verification. The image contains things like a nonsense font, which (depending on your computer) will fall back to a system font and be drawn very differently. They then add to this a 3D image with a special texture, which is drawn in such a way that the result varies between computers.

Finally, these seemingly simple little checkboxes combine all of this data with their knowledge of the person using the computer. Almost everyone on the Internet uses something owned by Google—search, mail, ads, maps—and as you know, Google Tracks All Of Your Things™️. When you click that checkbox, Google reviews your browser history to see if it looks convincingly human.

This is easy for them, because they’re constantly observing the behavior of billions of real people.

How exactly they check all this information is impossible to know, but they’re almost certainly using machine learning (or AI) on their private servers, which is impossible for an outsider to replicate. I wouldn’t be surprised if they also built an adversarial AI to try to beat their own AI, and have both learn from each other.

So why is all this hard for a bot to beat? Because now you’ve got a ridiculous amount of messy human behaviors to simulate, and they’re almost unknowable, and they keep changing, and you can’t tell when. Your bot might have to sign up for a Google service and use it convincingly on a single computer, which should look different from the computers of other bots, in ways you don’t understand. It might need convincing delays and stumbles between key presses, scrolling and mouse movements. This is all incredibly difficult to crack and teach a computer, and complexity comes at a financial cost for the spammer. They might break it for a while, but if it costs them (say) $1 per successful attempt, it’s usually not worth them bothering.

Still, people do break Google’s protection [PDF]. CAPTCHAs are an ongoing arms race that neither side will ever win. The AI technology that makes Google’s approach so hard to fool is the same technology that is adapted to fool it.

Just wait until that AI is convincing enough to fool you.

Sweet dreams, human.

This post originally appeared on Quora. Click here to view.

Why Are Sloths So Slow?

Sloths have little problem holding still for nature photographers.
Sloths have little problem holding still for nature photographers.
Geoview/iStock via Getty Images

When it comes to physical activity, few animals have as maligned a reputation as the sloth. The six sloth species, which call Brazil and Panama home, move with no urgency, having seemingly adapted to an existence that allows for a life lived in slow motion. But what makes sloths so sedate? And what horrible, poop-related price must they pay in order to maintain life in the slow lane?

According to HowStuffWorks, the sloth’s limited movements are primarily the result of their diet. Residing mainly in the canopy vines of Central and South American forests, sloths dine out on leaves, fruits, and buds. With virtually no fat or protein, sloths conserve energy by taking a leisurely approach to life. On average, a sloth will climb or travel roughly 125 feet per day. On land, it takes them roughly one minute to move just one foot.

A sloth’s digestive system matches their locomotion. After munching leaves using their lips—they have no incisors—it can take up to a month for their meals to be fully digested. And a sloth's metabolic rate is 40 to 45 percent slower than most mammals' to help compensate for their low caloric intake. With so little fuel to burn, a sloth makes the most of it.

Deliberate movement shouldn’t be confused for weakness, however. Sloths can hang from branches for hours, showing off some impressive stamina. And because they spend most of their time high up in trees, they have no need for rapid movement to evade predators.

There is, however, one major downside to the sloth's leisurely lifestyle. Owing to their meager diet, they typically only have to poop once per week. Like going in a public bathroom, this can be a stressful event, as it means going to the ground and risking detection by predators—which puts their lives on the line. Worse, that slow bowel motility means they’re trying to push out nearly one-third of their body weight in feces at a time. It's something to consider the next time you feel envious of their chill lifestyle.

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Are Any of the Scientific Instruments Left on the Moon By the Apollo Astronauts Still Functional?

Apollo 11 astronaut Neil Armstrong left the first footprint on the Moon on July 20, 1969.
Apollo 11 astronaut Neil Armstrong left the first footprint on the Moon on July 20, 1969.
Heritage Space/Heritage Images/Getty Images

C Stuart Hardwick:

The retroreflectors left as part of the Apollo Lunar Ranging Experiment are still fully functional, though their reflective efficiency has diminished over the years.

This deterioration is actually now delivering valuable data. The deterioration has multiple causes including micrometeorite impacts and dust deposition on the reflector surface, and chemical degradation of the mirror surface on the underside—among other things.

As technology has advanced, ground station sensitivity has been repeatedly upgraded faster than the reflectors have deteriorated. As a result, measurements have gotten better, not worse, and measurements of the degradation itself have, among other things, lent support to the idea that static electric charge gives the moon an ephemeral periodic near-surface pseudo-atmosphere of electrically levitating dust.

No other Apollo experiments on the moon remain functional. All the missions except the first included experiment packages powered by radiothermoelectric generators (RTGs), which operated until they were ordered to shut down on September 30, 1977. This was done to save money, but also because by then the RTGs could no longer power the transmitters or any instruments, and the control room used to maintain contact was needed for other purposes.

Because of fears that some problem might force Apollo 11 to abort back to orbit soon after landing, Apollo 11 deployed a simplified experiment package including a solar-powered seismometer which failed after 21 days.

This post originally appeared on Quora. Click here to view.

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