ELI5: How do people solve rubik`s cubes in <10 seconds?

Rubik’s cubes are actually solved with a formula, or simple set of rules. Once you know those rules by heart, it just becomes a matter of applying them in the most efficient way (to minimize the number of moves required) and then moving your hands very, very quickly. Those with good memories for images can actually look at the cube once then put on a blindfold and solve it from memory.

Fun fact - every possible (valid) permutation of a Rubik’s Cube has a solution which is no larger than 20 moves. This is called “God’s Number” and it took about 30 years to determine this number. Over 99% of all possible permutations require 16-19 moves to solve.

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ELI5: When you go on a roller coaster or drive fast down a hill, why do you get that stomach drop feeling? What is actually happening inside your body that causes the feeling?

“The honest answer is that no one knows with absolute certainty,” said Dr. Brad Sagura, a surgeon at University of Minnesota’s Amplatz Children’s Hospital.

“There’s a cast network of nerve connections within the body, handling messages between the spinal cord, the brain and other structures,” Sagura said.

When you hit the peak of a roller coaster and start dropping so quickly, things inside start to shift around.

“The liver and spleen are relatively secured by suspensory ligaments,” Sagura said. “But the intestines themselves are relatively mobile. While your body is secured by your seat belt, the organs are free to move about by some extent. That contributes to the free-fall floating sensation that either calls us back for more, or has us running to get sick from nausea.”

The movement isn’t only the movement of the organs, it is also the movement of what’s inside the organs.

“The intestines, the stomach, they hold liquid,” Sagura said. “The bladder; the same thing. “It’s relatively fixed, but the fluid within those structures probably plays a role in that sudden drop.”

Sagura said there’s no long-term danger from your organs slightly shifting around. They go back to where they started. But the movement is enough for your nerves to notice that something’s happening, he said.

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ELI5: Why do pens dry out when the cap is left off, but the caps themselves have holes?

The pens dry out because the ink contains solvents. The solvents are volatile and will evaporate if exposed to the air too much.

The caps slow this down but they don’t completely prevent it. The solvents will still evaporate but will largely just sit inside the lid if there’s no air moving past the pen.

The holes in the lid are there so children are less likely to choke and suffocate if they swallow one.

The pen cap holes are also useful to pass a balloon catheter through the cap to aid the removal of the cap from the child.

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ELI5: Why do we recognize that mirrors are "silver" when they appear to be the exact same color as what they are reflecting?

Not all mirrors are perfectly reflective, and things can be done to a mirror to make it less reflective (like fogging, smudging, etc).

If you look at something like the side of a butter knife, you can see that it has a color, despite also reflecting the world around it. If you polish the side of that knife enough, eventually you’d get a usable mirror.

Common household mirrors are a thin layout of silver on the back of a pane of glass, so their color when less than perfectly reflective is the same as the color of unpolished silver.

As had been pointed out, modern mirrors use aluminum, since it is almost as good but a lot cheaper. Still, the language evolved in a time when aluminum was less common.

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ELI5:How does rabies make it's victims 'afraid' of water?

The virus affects the entire body, and especially hits us neurologically. What happens when you’re thirsty and you see water? You salivate in anticipation of relieving that thirst. Salivation leads to swallowing, lest we drool. Well for someone in the later stages of rabies, swallowing becomes a very painful act…and as with anything painful, the mind tends to not want to repeat the act that leads to the pain. The Rabies virus causes severe muscle spasms in the throat, and even the sight of water can set them off. If that were happening to you, wouldn’t you be ‘afraid’ of water, too?

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ELI5: What is the purpose of the tiny parachute that is usually on top of the large parachute.

It’s called a pilot chute. It’s a miniature parachute that is several feet in diameter and is attached to the peak of a parachute and whose function is to draw the parachute out of its pack and extend it in position for opening.

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ELI5: The Panama Papers.

In business, you can avoid taxes by investing in something. If a company makes one million dollars, but spends 500,000 on investing in new technology for their product or something like that, they’re only taxed from the remaining 500,000 because that’s all of their “profit.” (I’m not a businessman so I’m not sure on the complete legality of all the kinds of spending but I think this is a basic summary). This is all normal and fine; all companies require investing in order to grow their company.

So a company in Panama basically made a business in creating fake businesses. Companies could “invest” million of dollars and then it wouldn’t be taxed, because according to legal documents it isn’t profit, it’s an “investment,” which is untaxable, and then they would get their money back from the fake business. So imagine if that $500,000 of investments from my above example was fake, and after awhile 90% of the money was given back to the business (I’m assuming the Panamian company took a cut of the money as payment). 2.6 TB of data in total, over 11 million documents and over 200,000 fake companies. According to the website that published the news of the leak, they were contacted by an anonymous source with encrypted files with the data sometime in 2015. Here’s am exerpt from the article:

Over a year ago, an anonymous source contacted the Süddeutsche Zeitung (SZ) and submitted encrypted internal documents from Mossack Fonseca, a Panamanian law firm that sells anonymous offshore companies around the world. These shell firms enable their owners to cover up their business dealings, no matter how shady.

Apparently there’s several trillion dollars of money that should’ve been taxed and wasnt. Not sure if that means trillions that should’ve been taxed off of, or trillions of dollars of straight tax money, but either way it’s a LOT.

Many political leaders (many seem to be in the Middle East), and celebrities are involved as well. To prevent any one person from being blamed for the leak, hundreds of news organizations are going to release further full details tonight (that’s what Ive heard, not sure how true it is) but the list apparently has thousands of people/companies on it. There’s 11 million documents though, and even though hundreds of journalists have been going through the data for months, there’s still information that has yet to come to light.

This goes much farther than tax evasion, and includes Syrian war crimes, human trafficking, and more. Here’s a video explaining it.

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