And while we know a LOT thanks to science, there’s still so much that we don’t know.
These mysteries have stumped scientists throughout the ages—and will leave you scratching your head.
11. Why did the octopus walk out of the sea?
No, it’s not a riddle. It really happened.
In 2017, dozens of octopuses emerged from the ocean and crawled along the coast of a seaside town in Wales for a nightly pilgrimage to no-one-knows-where… or why.
National Geographic reached out to several experts who provided various theories, including octopus-dementia, displacement of the octopus population because of storms, and an octopus population boom that has led octopus to search high and low for food.
But none of that explains why the exodus abruptly stopped three days later.
12. What happened to Amelia Earhart?
Amelia Earhart was the first woman to fly solo across the Atlantic and the first person to fly solo from Hawaii to the U.S. mainland.
But during an attempted flight around the world in July 1937, Earhart vanished over the Pacific, and her plane wreckage was never found.
Her disappearance remains one of the greatest unsolved mysteries of the twentieth century, according to History.com.
Did she crash and sink? Did she end up a castaway on a remote island? Was she captured by the Japanese? Scientists of all stripes have failed to crack this mystery… yet.
13. If a tree falls but no one's there to hear it...
If a tree falls when no one is there to hear it, did it actually make a sound?
The answer comes down to what is “sound”?
If sound is defined as airwave disturbances caused by motion, we could answer that yes, a sound exists even if no ears hear it.
But quantum theory holds that without a measuring device to record it, sound does not exist.
When scientists determine how sound is to be defined, we promise to let you know.