How do we calculate how big the universe is?
In: Physics
Depends what you mean by “big”. Are we talking mass or volume or linear dimensions?
1. Mass: Pick up the universe and stand on a scale. Write down the result. Now stand on the scale by yourself. Subtract this result from the previous one and you know how much the universe weighs. Weight = Mass. Don’t let them confuse you with fancy talk on this point.
2. Volume: Fill the universe up with water. Pour some of the water out into a 1 gallon jug to fill it. Make a hatch mark and then dump the water out of the jug. Repeat until universe is empty. Count up the hatch marks.
3. Linear dimensions: Go to one end of the universe and hold a tape measure. Send a friend to the other side of the universe holding the other end of the tape measure. Note down the length. If we assume the universe is spherical, that’s all the information you need. In fact, your friend didn’t really need to go all the way to the other end of the universe. She could’ve stopped when she reached Kanye and you’d have the radius. Don’t tell your friend this. She’ll be upset at all the extra walking you made her do. (Note: Applying the simple formula of 4/3πr^(3,) you can also use this information to calculate the volume of the universe. This is preferable to method 2 if you’re one of those eco-freaks who doesn’t like to waste water.)
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