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Density and Floating: Would King Lear Sink or Float in Lava?

Boop Tackles Shakespeare. You Can Too!

Hi! It’s me, Boop! I’m the Discovery World spokesturtle. We hope you continue to be well. It sure feels like Friday (hooray?), but it’s kind of hard to tell. Maybe it’s Thursday. No. This definitely feels like Friday. It’s Friday! I just know it.

It’s still April, I think, and there are signs of spring everywhere. I’ve seen some of them with my own eyes! The grass is growing again. I saw a bug the other day. Then I ate it. Daffodils are popping up. Robins are flittering about and rabbits are hopping around. So that’s something. When you can, get outside and look for signs of spring. How many can you find? What’s your favorite sign of spring?

Good news! You know how Shakespeare wrote King Lear while he was in quarantine? Guess what? I did, too! It was easy! It only took me a week. It’s a little shorter than the first one because I didn’t always understand what was going on. So I skipped a bunch of stuff (so much talking!). Also, my hand cramped up a lot. It’s more of a claw than a hand, but there was still cramping.

And I made some changes. Gloucester is a now a turtle. So are Cordelia and the Fool. King Lear is a red-eared slider. That’s a kind of turtle. Everyone else in the play is either a fish or a frog. Edmund is a poisonous dart frog. And everyone exits pursued by a bear. They also enter pursued by a bear. There’s a lot of running from bears.

Oh! And I fixed the ending. Instead of dying of a broken heart or whatever, a volcano erupts on stage, and Lear throws himself into it. That seemed more dramatic and fun. What I couldn’t figure out is if King Lear would be able to deliver his final lines from inside the volcano. What I mean is, would King Lear sink or float in lava?


Okay, let’s say that you’re about to leap into an active volcano. It’s a really active volcano, like it runs half-marathons and it’s super into CrossFit and yoga and everything.

Now, I don’t know why you’re leaping into an active volcano. Maybe you’re trapped in a Tom Hanks and Meg Ryan movie. Not Sleepless in Seattle, the other one. The other other one. The one with the volcano. Or maybe you’re playing the lead in Boop’s King Lear.

Anyway, you’ve made the leap. You’re plummeting through the air having all kinds of second and third thoughts. One question that no one was quite able to answer before you agreed to leap into the volcano was, “Will I sink or float?”

That depends on whether you are denser or less dense than lava.

Density is property of matter. It’s the amount of stuff in a given amount of space or mass per unit of volume. Density is measured in kilograms per cubic meter. It can be measured other ways, including grams per cubic centimeter and slugs per cubic foot. A slug here is a unit of mass not the slimy, terrestrial, gastropod mollusk (yum!).

A cubic foot of slugs would be super delicious. Better than mealworms, even! Actually, I don’t know if I’ve ever eaten a slug. You’d think I’d remember something like that. They sound good.

A cubic meter of air has a mass of 1.3 kilograms. A cubic meter of fresh water has a mass of 1,000 kilograms. So air floats on water, but you knew that already.

A cubic meter of ice has a mass of 917 kilograms. That’s why ice floats in water! Water is one of a few substances that are denser as a liquid than a solid. Water is weird. It’s awesome, but it’s weird.

Anyway, a cubic meter of people has a mass of 985 kilograms. A cubic meter of steel has a mass of 7,700 kilograms. Human beings float in water. Steel does not.

Hang on, you might say. Big ships are made of steel, and they float in water. True! But ships hold air. Most of the ship is air, so the overall density of the ship is less than water. A raft made of solid steel would be less successful as a means of aquatic conveyance.

FUN FACT! Turtles don’t float because our shells are denser than water.

But will you or a turtle or King Lear or Turtle King Lear float in lava? Lava, which is molten rock, has a density of around 3,100 kilograms per cubic meter. It’s over three times denser than water. You are slightly less dense than water. I am slightly denser than water. So, yes. You would float in lava. So would I. Don’t try this at home. Not that you could try this at home. I mean, I assume you don’t have an active volcano at home.

ANOTHER FUN FACT! If Lake Michigan were filled with mercury instead of water, a cubic meter of lava would float on it. Mercury (the metallic element, not the planet) has a density of 13,593 kilograms per cubic meter. Mercury is much denser than lava. Mercury the planet has a density of 5,420 kilograms per cubic meter, so Mercury would float in mercury. You’d need a much bigger, much deeper lake of mercury, though.

YET ANOTHER FUN FACT! Would the planet Saturn float in water? No. Saturn is less dense than water, yes, but there’s a different problem. Let’s say you were somehow able to place Saturn onto a ginormous planet covered entirely with water. This would be a massive planet about the size of a small sun. Okay, great. Saturn is made of gas, mostly hydrogen with some helium, methane, and a few other gasses. But Saturn also has a molten core made of rock.

The gravitational field of your hypothetical ginormous water planet is going to be much, much stronger than the gravitational field of Saturn. The hydrogen and helium would stay at the surface of your water planet while the rocky core would sink to the bottom. So some of Saturn would float, some would not. And after this experiment, Saturn wouldn’t really be a planet anymore.


The densest naturally occurring element is Osmium at roughly 22,500 kilograms per cubic meter. Neutronium (the stuff that neutron stars are made of) has a density of 1 quintillion kilograms per cubic meter. Grab a measuring teaspoon. Fill it with flour or sugar or sand or something. Now pretend that that teaspoon of stuff weighs 10 million tons. That’s how dense neutron star stuff is.

So that’s density in a nutshell. Or a volcano. Or something.

Anyway, the aquarists have promised me that we’ll stage a production of Boop’s King Lear next week! Beep and I are building the volcano now! It’s not a real volcano. Those are dangerous. And I have to teach fish how to talk and read and act. That should be fun. And after that I’m going to write Hamilton!

Be well,


Codes: Boop and Beep’s Great Mealworm Heist

Hi! It’s me, Boop! I’m the Discovery World spokesturtle. Did you know that turtles love mealworms? It’s true! We love mealworms. Mealworms, as I’m sure you already know, are delicious.

Actually, they’re more than delicious. Mealworms are succulent. Unctuous. Earthy, but with a gamey sweetness. They’re like beautiful little wriggling sausages filled with luscious worm goo, and they snap and simply burst in your mouth when you bite into them. I’m drooling just thinking about it. You probably are, too.

Now before I go any further, I have to tell you that the Discovery World aquarists are amazing. They take wonderful care of all the animals. They feed us. They take us for walks. Well, they take the turtles for walks. They don’t take the fish for walks. That wouldn’t work out so well. Anyway, the aquarists are awesome.

Back to the mealworms. Can I tell you a secret?

I didn’t know this until last week, but there’s a big box of mealworms in the refrigerator in the Reiman Aquarium kitchen. All the mealworms you’d ever need are in that box. I mean, I don’t actually know how many mealworms you eat. I don’t even know how many mealworms I eat. I know how many mealworms I would eat if I could get my claws on a big box of ‘em. I would eat all the mealworms.

Easier said than done, though. Those mealworms are locked up tighter than Fort Knox. The kitchen door requires a six-digit code that they change every twelve hours. The whole place is rigged with cameras and motion detectors. The refrigerator door requires an authorized fingerprint identification, which we can’t fake. And nothing goes in or out of the refrigerator without a retina scan, which we can’t get.

(And by we, I mean Beep and me. Beep is another box turtle who lives here at the Reiman Aquarium. Beep is my best turtle friend in the whole world!)

I wanted those mealworms. I needed to get into that refrigerator. This wasn’t going to be easy.

We didn’t have any of that high-tech heist equipment that you see in the movies. We didn’t have a computer hacker person who can hack their way into the refrigerator’s mainframe by typing really fast. We did not have a small fleet of Mini Coopers for a fun getaway. We did not have Alan Rickman. We did not have Charlize Theron. We didn’t have George Clooney or Bernie Mac. We didn’t have Vivica Fox or Queen Latifa. We did not have Michael Caine. We did not even have a plan.

We needed a plan.

And the whole plan depended on the aquarists not finding out about the plan. The problem is that the aquarists are so nosy!

Sure, they say that they’re “cleaning our tanks” and “making sure we’re healthy” and “feeding us” and “other stuff”. But they’re watching. Listening to our private turtle conversations. Waiting.

Whatever. Beep and I were going to make a plan. And we were going to keep that plan a secret.

At first, Beep and I wrote secret notes to each other with invisible ink. We dipped a cotton swab in lemon juice and then wrote our messages on paper. We’d wait for the lemon juice ink to dry, and then pass our notes to each other.

To turn the invisible message visible, all we had to do is hold it up to a heat source. Since all of the turtles have heat lamps in our tanks, invisible ink seemed like the perfect way to share secrets.

And it was for a while, but the Discovery World aquarists are pretty smart. Box turtles like me don’t usually eat lemons. We eat fruit, vegetables, leafy greens, bugs, mealworms (obviously), and a lot of other things. But not lemons. Or cotton swabs. But we kept asking for lemons and cotton swabs. The aquarists figured us out pretty quickly.

Undaunted, Beep and I switched to codes. A code is a word or phrase that means something else.

Let’s say I say something like, “The owl flies at midnight.” That might really mean, “Quick! Melissa the Aquarist left the big box of mealworms on the counter. Let’s take it before she gets back!”

Of course, that attempt depended on us being speedy. We are turtles. We are many things. Speedy is one of them.

Anyway, codes are fun, but we ended up with a huge book of them. Two books, actually, because Beep needed to keep track of all the codes, too. Of course, the aquarists found our code books one day when they were cleaning our tanks. Always keep your code books well hidden!

Well, now Beep and I were really undaunted. So we switched it up again and started using a cipher. A cipher is an algorithm, a set of step-by-step instructions to transform actual words into strings of nonsense.

To encrypt our plaintext (our notes to each other), we would take our messages and shift each letter of the alphabet by a certain amount. This would generate the strings of jibberish (the ciphertext). 

For a 2-shift cipher, you shift all the letters of the alphabet two places. A becomes C, B becomes D, C becomes E, and so on.

So the phrase, “Hello! My name is Boop!” becomes, “JGNNQ! OA PCOG KU DQQR!” It looks like Klingon, but it’s nonsense. Of course, both Beep and I knew what the shift was for that day. So we could decipher our messages almost instantaneously.

Our messages would look like this:


(Hi, Beep! Are you awake? Should we get a late night snack of mealworms from the fridge?


(Hi, Boop! It’s really late. Can you please stop thinking about mealworms and go to sleep?)

Obviously, Beep was just as excited about the Great Turtle Mealworm Heist as I was.

Try it! You can shift the letters anyway you want as much as you want, as long as you and your co-conspirator agree on what the shift is for each message.

And ciphertext doesn’t have to be made of letters. Your algorithm could generate numbers or strings of binary code or anything, really. Your algorithm can swap letters randomly or pseudo-randomly. You’re good as long as the person receiving your message can reconstruct the plaintext from the ciphertext.

The point is that once again the aquarists couldn’t read our messages! Ha! The turtles were back in business! And we were back in business for… a while. Again, the aquarists are pretty smart.

Even though Beep and I made sure to choose a different letter-shift each day so that the aquarists couldn’t possibly decipher our messages, they did decipher our messages. Easily.

The aquarists could have tried what’s called a brute force attack. They could’ve tried every possible letter shift until they found the one we were using for that day. The problem with this strategy is that it takes a long time, at least for people.

Computers can do a brute force attack on a simple letter-shift cipher in almost no time at all. Our aquarists are not computers. They’re busy people with a lot of important work to do. That’s what Beep and I were counting on. But it turns out that they didn’t have to use a brute force attack at all. We made mistakes.

Our biggest mistake is that we put what are called “cribs” in our messages. A crib is a word or a phrase in a message that gets used a lot. For example, we began pretty much every message with, “Hi, Beep!” or “Hi, Boop!” Also, most of our messages were about mealworms. All the aquarists had to do was find these cribs and figure out the pattern. Then they could easily decipher the rest of the message.

Our other mistake was that Beep and I were not the first people (or turtles) to use this kind of cipher. It’s been around for thousands of years. We did not know that.

If you need to send secret messages, there are lots of different codes, ciphers, and things you can use. Beep and I are now working on a totally new (we think) kind of encryption using very, very large prime numbers. It’s possible that Ron Rivest, Adi Shamir, and Leonard Adelman worked this out years ago, but maybe not.

Here’s (mostly) how it would work, I think. We’re still figuring out all the details. I type a message to Beep. An encryption algorthim picks two very, very large prime numbers. Hundreds of digits long. Let’s call these numbers p and q. I keep these numbers secret.

The algorithm multiplies them together to get a new number. Let’s call that number N.

N is the public key. I share that number with Beep. I could share that number with the aquarists, too, if I wanted. It wouldn’t matter. Why? Because it’s easy for a computer to multiply numbers. Factoring them is difficult. Computers are really, really fast at math, but there’s so much math to do that a brute force attack would take longer than the current age of the known Universe.

Then math stuff happens, lots of fun math stuff involving Euler’s totient function and a few other things that we’re still working on. Essentially, my computer will have a private lock. It generates a key and makes that key public. It will be easy for Beep’s computer to figure out the encrypted message that I send. But it will be almost impossible for any other computer (or a nosy aquarist!) to decrypt the message.

If we do figure it out, we’ll need a snazzy name. RSA encryption or something. And we will use it RSA encryption to finally make that plan so we can finally break into the refrigerator and finally grab that big box of mealworms.

Unless the aquarists build a quantum computer, which seems unlikely. Then we’ll have to figure something else out. But we are turtles! We are never daunted. We exist in a continuous state of undauntedness! You probably do too.

I wonder who will play me in The Great Turtle Mealworm Heist movie. Maybe Donald Glover. That would be cool. Donald Glover is awesome.

Of course, Beep and I still have to pull off the actual heist. But there is time. Lots of time.


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Getting Here

We are located on Milwaukee’s lakefront with easy access on and off of the expressway.

500 N Harbor Dr
Milwaukee, WI 53202
Get Directions
Adults $20
Child (3-17) $16
Child 2 & Under $Free
Senior (60+) $16
College Student* $14
Military Active and Veterans* $14
Military* Active Duty & Veterans $14

*Valid ID Required.

Prices are subject to change. Click HERE to buy tickets and for important information you need to know before visiting. 

Current Hours

Mon-Tue: Closed | Wed-Fri: 9am-4pm
Tues-Fri Mon-Tue: Closed | Wed-Fri: 9am - 4pm
Sat & Sun 9am - 4pm
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