Is This Scientific Common Knowledge Fact True or False?


By: Zoe Samuel

6 Min Quiz

Image: shutterstock

About This Quiz

There are certain things that everyone knows to be true. For example, the Earth is a flat disc at the center of the universe. All the stars and planets rotate around it. The whole planet is only 6,000 years old and it was created in seven days, and its climate is definitely stable and not at all affected by emissions of carbon dioxide. Humanity came into being fully formed and is not related to apes in any way. Then, there are facts like how organic food is always healthier, coffee stunts your growth, all fingerprints are totally unique, humans have five senses, ghosts are real and so on. 

Of course, all of these things are nonsense. Either they're completely disproven - the world is certainly much older than 6,000 years - or they are questionable at best. However, at some point or other, every single one of them was considered an unassailable fact that only a very silly or mad person would possibly contest. This is the genius of science. Science, like humans, is always evolving, and that means that what we know to be true one day always comes with the caveat that new evidence may prove us wrong - or at least, reveal the truth more precisely. Staying on top of the truth means always keeping up to date with what we know, and being open to the possibility that we may know more tomorrow, and that will mean changing our minds.

How much do you know about facts as they stand now? Let's find out!

The Earth is 13.8 billion years old. True or false?

The universe is that old. The Earth is much younger, at a sprightly 4.5 billion years.


The Earth is a sphere. True or false?

It is slightly flattened at the poles due to the effects of its rotation and gravity. That means it is an oblate spheroid.


If you have 23 people in a room, the odds that two of them share a birthday are higher than 50%. True or false?

This one is amazingly counter-intuitive. It all comes down to the fact that the first pair only have a 1 in 364 chance of sharing a birthday, then as you add people, the numbers change until at the 23rd, person, it's more than 1 in 2.


Cashnew nuts grow out of a kind of apple. True or false?

The cashew apple is edible and the nut grows out of its base. Try some cashew apple juice for a high energy drink with plenty of protein and good fats!


Human bodies are 70% water. True or false?

It actually depends on your age and fat content. Babies are up to 75% water but adults are only 55-60% water.


Humans have 99% of the same DNA as apes. True or false?

That's why it's a bit silly when we get hung up on differences between us, considering that any two humans are overwhelmingly alike when you compare us to literally any other living thing. It's not just hippie talk to say we really are all the same!


Water conducts electricity. True or false?

Minerals in water conduct electricity. Purified water would actually serve as insulation.


Humans only use 10% of our brains. True or false?

You use all of your brain, but not all at the same time or in the same way. Some of your brain's weight is actually insulation of other parts of your brain - but you're still using it. Other parts are used more of less often.


The Great Wall of China is the only man-made structure visible from space. True or false?

You can't actually see it from space. The first Chinese astronaut up there was not popular when he discovered this.


Goldfish have a three-second memory. True or false?

Goldfish can definitely remember things like where to find food, so this is not true.


Lightning never strikes the same place twice. True or false?

As anyone who has ever put a lightning conductor on their roof knows, lightning can strike the same place many, many times.


If you cut a liver in half, it will grow back. True or false?

It will only do this if it is inside a human, but yes, you can re-grow your liver. That means if someone you know needs a liver, you should definitely give them some!


If something is a scientific theory, that means it has not been proven true.

"Theory" is a bad word for scientists to use, really, because it means a different thing in science. It means a hypothesis (a guess) that has since been proven correct by a mountain of evidence. Laypeople who say, "It's just a theory" about scientific theories are using the word wrong.


There is a side of the moon that never gets any sunlight. True or false?

The moon rotates around the Earth so the same side always faces us, but that doesn't mean the other side never sees the sun: it does, we just don't see that happening because we only see one side. The moon therefore has a FAR side, not a DARK side.


Your hair and fingernails grow after death. True or false?

They look like they grow because your skin shrinks onto your body and makes them stick out a little more. Creepy, huh?


Humans have five senses. True or false?

You have loads of other senses: balance, direction, temperature, etc.


7% of people who have ever lived are currently alive. True or false?

About 108 billion people have ever lived. About 7 billion are alive now. Population growth for the win!


Greenland sharks can live 500 years. True or false?

The longest-living shark recorded was 272. That is not to say a Greenland shark could never live 500 years, only to say that none has come close, as far as we know.


A sugar cube-sized lump of a neutron star would weigh 100 million tons on Earth. True or false?

Neutron stars are stars that collapsed in on themselves. They are really, really dense. A tiny little piece of one thus weighs a very ridiculous amount.


One 18-inch pizza is actually less pizza than two 12-inch pizzas. True or false?

It's true! The area of a circle is the radius squared, multiplied by Pi. The radius is half the diameter. So an 18" pizza has a 9" radius. That means the area is just over 254 square inches. A 12" pizza has a 6" diameter, for an area of just over 113 square inches. Two such pizzas have an area of 226 square inches, which is smaller than 254! Order the big pie, is what we're saying.


There are more trees on Earth than stars in the Milky Way. True or false?

There are 400 billion stars in our galaxy, but there are three trillion trees on our planet!


Days on Venus are longer than years on Venus. True or false?

Venus has a day (one rotation on its axis) that is nearly 243 days, but its year (once round the Sun) is only 225 days. So its year is shorter than its day.


It rains diamonds on Jupiter.

It sounds too good to be true, but it's not. Jupiter is a gaseous planet with lots of methane in the atmosphere to provide carbon. When it gets too low down, the amazing gravity levels squash the carbon into diamonds. It literally rains diamonds there.


Horses cannot throw up. True or false?

This is true and it is why horses are very vulnerable to colic. Never get a horse drunk, either!


If you cry in space, the tears just ball up on your eyes until you wipe them. True or false?

It's true! If you squeeze a wet towel you will see the same thing, the water just hovers around the towel and refuses to go anywhere.


Gorillas can use human birth control and it will work. True or false?

It does work, weird though it seems. It's not clear whether gorillas get any of the same potential side effects, whether the good ones (improved mood and complexion) or bad ones (weight gain and depressed mood).


Male seahorses, not female ones, carry the fertilized eggs to term. True or false?

Male seahorses are really showing up for equality. They take the fertilized egg back from the mother and carry it to term.


Wolf packs are led by an alpha male. True or false?

Actually, wolf packs are an extended family led by a female and male pair. The two are equally in charge. "Alpha males" are not a real thing in nature, they only exist when wolves are in captivity and start behaving in ways they have never been observed to behave in the wild.


The furthest man-made object from Earth is 1 billion miles away. True or false?

The Voyager probe is actually 11.7 billion miles away, and it still sends us back all sorts of information.


You can't crack an egg at the bottom of the ocean. True or false?

You can, but its insides won't come out, or if they do, they won't leak away from the egg. This is because of the 2.8x atmospheres of pressure down there.


A Mobius strip only has one side. True or false?

It's true, and you can test it right now by making one. Cut a strip of paper, twist it once, then tape the ends together. Take a Sharpie and draw a continuous line, never taking it up from the paper. You will finish that line back where you started.


Male sharks have thicker skin than female sharks. True or false?

Actually, female sharks have thicker skins than male. It is believed it is because male sharks bite during mating!


Babies have more bones than adults. True or false?

Babies' bones fuse from about 270 at birth to the 206 they have when they are all grown up!


Mercury is the only metal that is a liquid at room temperature with just one atmosphere of pressure.

Mercury behaves very differently to other metals due to the nature of the bonds between its neutrons.


Motor neurons are the largest cell in the human body.

They can be up to 4'7" and run from the base of the spinal cord to the toe!


Explore More Quizzes

About HowStuffWorks Play

How much do you know about dinosaurs? What is an octane rating? And how do you use a proper noun? Lucky for you, HowStuffWorks Play is here to help. Our award-winning website offers reliable, easy-to-understand explanations about how the world works. From fun quizzes that bring joy to your day, to compelling photography and fascinating lists, HowStuffWorks Play offers something for everyone. Sometimes we explain how stuff works, other times, we ask you, but we’re always exploring in the name of fun! Because learning is fun, so stick with us!