Sometimes a question that seems simple turns out to be more difficult in unexpected ways.
Why does your hair actually stand on end when you rub a balloon? The common answer from science class is that negatively charged electrons move from your hair to the balloon, making your hair positively charged.
The hairs stand on end because the electrically charged hairs push against each other.
But why do electrons move from the hair to the balloon? Why not the other way around? That's a very good question.
Because nobody knows the answer.
Physicists have no plausible, general theory as to why some materials shed electrons from their surfaces when in contact, while others accept them.
This phenomenon, called triboelectricity, is a cutting-edge area of ​​research.
The same science is used to answer serious questions and silly questions.
Frictional electricity explains how lightning is created in storms.
Counting the number of subatomic particles in living organisms is something physicists need to do when conducting radiation experiments.
Answering stupid questions can lead us into the realm of serious science.

--- pp.10~11

Q.
Would it be dangerous to be next to a large object that has a temperature of 0 Kelvin, or absolute zero?
A.
One of the great dangers of extremely cold substances is that they often do not want to remain extremely cold.
When liquid nitrogen or dry ice warms and turns into a gas, it expands greatly and can push all the air out of a room.
A single bucket of liquid nitrogen can be converted into enough nitrogen gas to fill a room.
If you breathe oxygen, this is bad news.

--- p.27

Q.
Is the universe hot or cold?
A.
According to the textbook definition of temperature, the universe is hot.
At least here in our solar system.
Molecules in space move individually very quickly.
Each has a lot of energy, and temperature is roughly defined as the average kinetic energy of the molecules.
But because there are so few molecules in space, even though each has a lot of energy, the total amount of thermal energy is small.
It means that you can't heat an object.
Space may be warm in theory, but in reality it feels cold.
Space is hot, but it's the hottest place you can freeze to death.
--- pp.119~120

Q.
What is the maximum height a person can swing a swing by simply swinging their legs? Is it possible to build a swing so high that a rider could launch into space if they timed their jump perfectly?
A.
There is a place with a very large swing.
At Moses Mabhida Stadium in Durban, South Africa, spectators can climb high up and ride on a 60-meter-long swing suspended from the stadium's structure.
But at that speed, air resistance is very strong.
When a person on a swing reaches the bottom, they have lost most of their momentum and cannot go up very far in the opposite direction.
Kicking doesn't help much.
Because the swing is so long, rowing it is virtually ineffective.
A giant swing might be fun, but it won't help you get into space.
Measurements taken by average people have shown that the ideal swing length to allow maximum height is between 3 and 4.5 meters.
It's exactly the length of a swing in a large playground.
Once again, the kids are the most accurate.

--- pp.105~107

Q.
If plastic is made from oil, and oil is made from dead dinosaurs, how much of a real dinosaur is in a plastic dinosaur?
A.
No matter where it comes from, only a very small percentage of the oil in your plastic dinosaur comes directly from the carcasses of real dinosaurs.
If the oil came from a Mesozoic oil field with a rich terrestrial supply, it could contain slightly more dinosaurs.
If it comes from pre-Mesozoic deposits trapped under the caprock, it probably doesn't contain any dinosaurs.
There's no way to know without painstakingly tracking every step of your particular toy's manufacturing process.
In a broad sense, all the water in the ocean was part of the dinosaurs at some point.
When this water is used for photosynthesis, the water molecules become part of the fats and hydrocarbons in the food chain.
But there's a lot more water in your body right now, in the form of water.
So, there's more dinosaurs in your body than in your plastic toys.

--- pp.163~164

Q.
If up to 80 percent of household dust is made up of dead skin, how much human skin will a person inhale in their lifetime?
A.
Good news: You can't breathe it in, and most dust isn't dead skin.
(…) Even if we figured out how to maximize the amount of floating skin dust, it wouldn't be enough to inhale a single person.
Even if we built a machine that pumped skin dust into a room and increased the density of skin dust to 10 milligrams per cubic meter (making the air dusty enough to exceed the dust exposure limit for coal miners), we would only inhale about 3 kilograms of skin cells over the average lifespan.

--- p.258