Sunday, 22 May 2016

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.




Explain Like I`m Five: good questions, best answers.


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Saturday, 14 May 2016

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.

Explain Like I`m Five: good questions, best answers.


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