5 Unexplainable Mysteries Explained by Science

0:00 Thanks to Skillshare for sponsoring this episode— and this whole week!

0:04 of SciShow.

0:08 INTRO] To the frustration of scientists everywhere,

0:17 things in this world sometimes just don’t make any sense.

0:21 But for the rest of us, that can be kind of amazing.

0:24 Imagining what could cause unexplained phenomena— like weird lights in the sky,

0:28 or sightings of mythical creatures— can be a lot of fun.

0:32 Just ask half the forums on the Internet.

0:34 But it’s also good to remember that the world doesn’t

0:36 have to be shrouded in mystery for it to be fascinating.

0:39 Exploration can be just as cool as speculation.

0:42 So to that end, here are six mysteries— from the Easter

0:46 Island statues to will-o’-the-wisps— that scientists have managed to solve.

0:50 We’ve talked about all kinds of weird weather here on SciShow,

0:53 but this might be one of the best and most horrifying stories yet.

0:58 Imagine it’s March 1876, and you’re living in Bath County, Kentucky.

1:02 You’re outside on a beautiful,

1:05 perfectly clear spring day when the unthinkable happens:

1:09 It starts to rain chunks of meat.

1:11 Some of them are small— about 5 by 5

1:13 centimeters— but others are as big as your hand.

1:15 And soon, your yard is covered in the stuff.

1:19 I wish I could say this wasn’t a true story, but yeah,

1:22 this 19th-century version of “Cloudy

1:23 with a Chance of Meatballs” actually happened.

1:26 According to the New York Times,

1:27 two guys even tasted the meat rain— because they just had

1:30 to be curious— and decided it was either mutton or venison.

1:34 This event came to be called the Kentucky Meat Shower,

1:37 and it baffled people for decades.

1:38 Originally, one person thought the culprit was something called nostoc— which we

1:42 now know is a kind of bacteria covered in a jelly-like membrane.

1:46 And when it rains, that membrane swells up.

1:49 Except, it wasn’t raining when the meat shower happened,

1:52 so that idea was tossed out the window.

1:55 Eventually, though, scientists did figure it

1:58 out after studying some preserved samples.

2:00 They found that the meat was meat— specifically,

2:06 a mixture of animal lung tissue, muscle, and cartilage.

2:10 And later in 1876, the chemistry professor L.D.

2:13 Kastenbine discovered where it came from: synchronized,

2:17 projectile vomiting vultures.

2:19 This story is amazing.

2:21 There are two species of vulture native of Kentucky,

2:24 and their eating habits totally explained the shower.

2:28 For one, vultures aren’t picky eaters,

2:29 which is why there were various kinds of tissue,

2:32 and why the meat pieces were all different sizes.

2:34 But more importantly, vultures are also frequent vomiters.

2:38 Vultures are known to eat huge meals,

2:40 and if they’re disturbed before they have time to digest all that food,

2:43 they sometimes throw it up to make themselves lighter and make escape easier.

2:53 So Kastenbine concluded that, on that day in Kentucky,

2:55 a group of vultures just happened to be flying overhead,

2:59 and all puked at the same time.

3:01 It’s possible that this has even happened in other places,

3:04 too, but cases haven’t been well-documented.

3:06 Either way, yeah, it’s a little gross.

3:09 But it’s the Kentucky Meat Shower,

3:11 there was never going to be a not gross explanation Easter

3:14 Island in the southeast Pacific is famous for its giant statues.

3:17 They’re called moai,

3:18 and they were built at least 400 years ago by the Rapa Nui people of Polynesia.

3:24 But here’s a lesser-known fact: Those statues used to have little, reddish hats.

3:27 Okay, maybe “little” is an understatement.

3:30 The hats were about two meters across and weighed up to 12 metric tons.

3:33 And until 2018, it was pretty unclear how

3:36 the Rapa Nui managed to put them on the statues.

3:40 After all, the moai are some 10 meters tall, and the hats were really heavy.

3:45 Also, it was hundreds of years ago.

3:47 Cranes were a little on the scarce side.

3:50 But using modeling, a team finally figured it out.

3:53 In a 2018 paper published in the Journal of Archeological Science,

3:57 researchers discovered that the Rapa Nui

3:59 likely used a technique called parbuckling.

4:01 First, they would have carved the stones into cylinders.

4:05 This red rock is actually found on the other side of Easter Island,

4:09 so making a cylinder out of it allowed them

4:11 to roll it over to where the moai were.

4:13 Then, they built a ramp leading up to a statue’s head.

4:16 They tied a rope around the cylinder,

4:18 and then a team of probably 15 people hauled it

4:21 up the ramp and put it on top of the statue.

4:25 After that, the hat was carved into its final shape.

4:28 It sounds like figuring that out would have been easy,

4:31 since it’s all based on simple machines

4:32 you might have learned about in elementary school.

4:35 But discovering this required building 3D models

4:37 of about 50 statues and 13 cylinders,

4:40 as well as making all kinds of calculations about the weight

4:43 of the rocks and the strength of the average ancient Polynesian.

4:46 Today, you probably won’t see many of these hats still on their moai,

4:50 since weather and erosion have knocked most of them off.

4:53 But at least they’re no longer a mystery.

4:55 Scientists can’t tell us how to predict an earthquake,

4:58 since there are so many variables to keep track of.

5:01 But they can tell why before and during ‘quakes,

5:04 people have sometimes reported seeing mysterious lights in the sky.

5:08 They’re called earthquake lights, and they can take all kinds of forms,

5:12 from blue flames to lightning that shoots out of the ground.

5:15 People have recorded seeing them as far back as the 1600s,

5:18 and they’ve been observed up to weeks before major

5:22 earthquakes and up to 160 kilometers from the epicenter.

5:25 Unsurprisingly, some people blamed these lights on UFOs.

5:28 Others thought they were caused by disruptions in the Earth’s magnetic field.

5:32 But the real answer came in 2014,

5:35 in a paper published in Seismological Research Letters.

5:39 In it, the authors investigated data from 65

5:42 earthquakes where people had reported seeing lights.

5:45 And they found that, most likely,

5:47 the culprit was electrical activity in certain types of rocks,

5:51 especially volcanic ones.

5:52 The team discovered that, when you put a lot of stress on these rocks,

5:55 they can release electric charge.

5:57 The pressure causes the chemical bonds between

6:00 certain compounds in the rocks to break, which releases charged oxygen atoms.

6:04 If enough bonds are broken at once— like before or during a big

6:08 earthquake— a bunch of those charged atoms can rush up to the surface,

6:12 usually at a fault, where two sheets of rock meet.

6:15 Then, when they burst above-ground,

6:17 they can ionize the air, giving /air molecules/ electric charge.

6:21 And that ultimately creates the various flashes of light.

6:24 The conditions that cause these are pretty specific,

6:26 which explains why earthquake lights are only seen in about 0.5% of earthquakes.

6:30 And the team also mentioned that this phenomenon

6:33 can explain other things detected before quakes,

6:36 like low-frequency radio emissions.

6:38 Unfortunately, understanding earthquake lights probably

6:40 won’t help us predict ‘quakes,

6:42 since they’re so rare and since people usually don’t report them.

6:46 But hey… take that, UFOs!

6:50 With average summer temperatures around 45°C,

6:53 California’s Death Valley probably isn’t a place you’d want to sit for very

6:57 long— unless you’re trying to solve the mystery of the Sailing Stones.

7:01 These are rocks that sit in one of the valley’s dry lake beds,

7:05 called the Racetrack.

7:06 They can weigh up to 320 kilograms, and they seem to move… by themselves.

7:11 Of course, they don’t move very much.

7:15 Some can sit in the same spot for decades.

7:17 But they usually leave long streaks behind them as they travel,

7:20 and that shows us that some of these rocks have moved more than 450 meters.

7:24 For years, people couldn’t figure out what was going on.

7:30 Explanations ranged from hurricane-force winds to films of algae.

7:34 And to make matters worse, no one had actually seen a rock move.

7:39 That is, until a few years ago.

7:43 In 2011, a team of researchers tried to solve the mystery of the Sailing Stones

7:46 by sticking GPS sensors on them and then…

7:50 just kind of waiting for something to happen.

7:52 Since the rocks move so infrequently,

7:53 one of the paper’s authors expected this to be,

7:55 quote, “the most boring experiment ever”.

7:58 Two years into the project,

8:00 a couple of the scientists showed up at the Racetrack to make observations,

8:04 only to discover the lake bed covered in a thin layer of water.

8:09 And then, to their amazement… they saw some of the rocks move.

8:12 They eventually published their paper— and the solution

8:15 to the mystery— in PLOS One.

8:17 According to the team,

8:19 the Sailing Stones only move under specific circumstances.

8:21 First, the Racetrack has to fill with water,

8:24 deep enough to form floating sheets of ice,

8:28 but shallow enough not to cover the Stones.

8:30 At night, the surface of the water has to freeze.

8:33 Then, in the morning, the ice has to break up into floating panels.

8:36 Under the right conditions,

8:38 the wind will push those panels of ice across the surface of the water,

8:42 and the ice will push the Sailing Stones.

8:45 It sounds impossible,

8:46 but it makes more sense if you realize that the Stones aren’t sailing very fast.

8:50 At most, they move 2 to 6 meters per minute—

8:53 which you might not notice if you weren’t looking closely.

8:56 But over the years, that can add up,

8:59 creating those famous, long tracks across the ground.

9:02 There is one more mystery that remains, though:

9:04 Researchers aren’t positive this method also applies

9:06 to the biggest rocks in Death Valley.

9:09 So there’s still one more thing to be solved.

9:12 With so much of the ocean being unexplored,

9:14 it makes sense that there’s a lot we don’t understand about it.

9:18 And whenever we discover something we can’t explain,

9:20 people are pretty quick to get out their sea monster T-shirts.

9:22 That’s what happened when we heard the Bloop in 1997.

9:27 Yes, that is the official term.

9:30 Because it sounds like… well, a bloop.

9:33 The sound was recorded off the coast of South America,

9:36 while researchers were looking for underwater volcanoes, and it was really loud.

9:41 It was captured by microphones more than 4800 kilometers apart,

9:44 making it way too big for something like a ship or a whale.

9:49 It also didn’t help that NOAA at one point announced that the sound was, quote,

9:53 “possibly biological.” But in 2005, nearly a decade later,

9:58 scientists found that it definitely wasn’t.

10:00 As they recorded more sounds in the ocean, especially ones near Antarctica,

10:05 they concluded that the Bloop was probably an icequake.

10:08 That’s where a huge chunk of ice cracks off a glacier.

10:12 It makes a ton of noise, and audio recordings taken over several years

10:16 show that they sound just like the Bloop.

10:19 No sea monsters required.

10:21 Finally, will-o'-the-wisps.

10:23 You can find stories about them— or something

10:25 similar— in folklore from around the world,

10:27 and you may have even seen them yourself if

10:29 you spend a lot of time in marshes or swamps.

10:32 Hey, I don't know your hobbies.

10:35 They're blue-ish lights that drift over these kinds of landscapes,

10:39 and if you get too close to one— like Merida in Brave— it will disappear.

10:43 According to many legends,

10:44 they're some kind of spirit or creature out to mislead curious travelers.

10:49 But in reality, the explanation for these lights...

10:52 well, actually, it's almost as strange.

10:54 Because will-o’-the-wisps are probably caused by spontaneous combustion.

10:59 Not spontaneous human combustion, though— that almost definitely isn’t a thing.

11:03 Just the regular kind,

11:05 where something bursts into flame without an obvious source.

11:08 In this case, the lights are likely caused

11:10 by certain mixtures of gas reacting with atmospheric oxygen.

11:14 These mixtures consist of things like methane,

11:16 carbon dioxide, and, most notably,

11:18 compounds containing phosphine— like one called diphosphane,

11:21 which is known to ignite in the presence of oxygen.

11:24 Various studies have shown that these gases can be produced in marshes, swamps,

11:29 and cemeteries, likely by bacteria living

11:31 in the soil and breaking down organic matter.

11:34 And when bubbles of that gas make it up to the surface,

11:37 poof— you have a will-o'-the-wisp.

11:38 It is worth noting that there are other

11:41 hypotheses suggesting these lights might not be actual fires,

11:44 but just clouds of glowing gas.

11:46 An experiment published in 1980, for example,

11:48 showed that you get a sort of glowing

11:50 green cloud if you mix crude phosphine and methane.

11:54 But either way, the general mechanism of "swamp

11:57 gas+ air" does seem to explain what's going on.

12:01 Since these reactions are pretty short-lived,

12:02 it even explains why these lights seem to disappear if you approach them.

12:06 Also, researchers have pointed out

12:08 that some phosphine derivatives are super toxic.

12:11 So if dangerous gas clouds kept popping up in local swamps,

12:14 that might have made people especially eager to stay away.

12:18 Everybody loves a good mystery,

12:19 but the stories about how we solve mysteries are pretty fascinating, too.

12:25 After all, it takes a lot of curiosity and wonder to become

12:29 a professional scientist and say “You know what I want to study?

12:32 The Bloop.

12:33 Or will-o’-the-wisps.” Thanks for being curious, scientists.

12:38 For centuries, people have been telling

12:40 amazing stories about phenomena like this.

12:42 And even though scientists can explain how some of them happen,

12:45 that doesn't make the stories themselves any less worthwhile.

12:48 Which is why I'm glad that Skillshare has so many classes on storytelling.

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14:04 outro]