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• Hey, Vsauce, Michael here, and what if every single person on Earth jumped at the exact

• same time? Could it cause an earthquake, or would we not even be able to tell?

• Well, first things first, let's talk about the Earth's rotation.

• The Earth spins, that's why we have night and day, and it spins quickly. At the equator,

• the Earth is spinning at more than 1,000 MPH.

• Now, a spinning ice skater can speed up by moving mass closer to the center, and the

• Earth is no different; In fact, if you get down on the ground right now and move your

• mass closer to Earth's center, technically, you will speed up Earth's rotation, making

• this day shorter.

• Now, the change that you would make to the Earth's rotation is way smaller than we could

• even measure, but it is calculable, and the impact can be quite impressive when you talk

• about redistributing more mass than just one person.

• For instance, last year, the earthquake in Japan redistributed so much of Earth's mass

• towards the center, that every day since then has been 1.8 microseconds shorter.

• But, that was a giant geological event. What can us humans do to the Earth all on our own?

• I mean, there are more than 7 billion of us now- what if we all got together in one place

• and jumped?

• Well, what would that even look like?

• Interestingly, if you took the entire human population of Earth and had them all live

• in one place with the same density that people live in in New York City, you could fit everyone-

• all of us- into the state of Texas.

• But that's living, not standing around in a crowd, which is how we would probably want

• to do the jump.

• If every single person alive right now on Earth stood shoulder to shoulder, you could

• fit all of us into the city of Los Angeles. It would be an incredible sight to behold-

• a mere 500 square miles containing every single person on Earth.

• Ok, so, then we jump. What happens?

• Unfortunately, not much. I mean, we're all awesome people here on Earth, but our collective

• mass compared to the mass of the entire Earth? It's like, nothing.

• In fact, Dot Physics calculated that if all of us were to get together in one location

• and all jump 30 cm into the air at the exact same time, we would push Earth away from us

• a tiny amount.

• Earth would only move away from us about 1/100th of the width of a single Hydrogen Atom. And

• here's another thing: because we're all jumping and the going back to where we started, Earth

• is just going to move back to where it started.

• So, our big jump won't be able to change Earth's position in space, but, c'mon, 7 billion people

• all jumping together? That's gotta be able to cause some sort of seismic activity, right?

• So, let's say you have a lot of people all together in one place, and you have them all

• jump on: 1-2-3!

• Did you feel that? Well, the BBC did this with 50,000 people, and discovered that a

• kilometer and a half away, it only registered a .6 on the Richter scale. You would need

• 7 million times more people than even live on Earth right now to jump at once to recreate

• the earthquake that recently happened in Japan.

• So, even though we're all awesome, compared to the size of the Earth, we're not much.

• But don't get too discouraged. Our collective jump would contain a lot of energy. The Straight

• Dope calculated that even if only the people who lived in China got together and jumped,

• their jump would be the equivalent of 500 tons of TNT. Of course, 500 tons of TNT doesn't

• do much to an Earth that weighs 6 sextillion, 588 quintillion tons.

• To make yourself feel more powerful, pick a card. I've got 10 of them here, let's say,

• hmmm, you choose this one. Boom, congratulations, we have just decimated this deck of cards.

• Why? Well because, technically, decimate does not mean "obliterate completely."

• Deci=10. It means to take away 1/10th of something. So, the next time you take a quiz and don't

• do so well on it- you only get 10%, well sure that's an "F", but, by getting 10% of them

• right, you DECIMATED that quiz.

• that view count that you see at the bottom of every video, and get some perspective on

• it.

• We'll being with Dunbar's Number.

• It's an estimation of the maximum number of people we can have stable, social relationships

• with at a given moment, and it's based on the size of our neo-cortex.

• These aren't just acquaintances, these are people you have social contact with; a network

• where you know how everyone relates to everyone else. And the number is usually given to be

• somewhere between 100-230, which means that when a YouTube video receives more than 230 views

• from different people, more people have seen that video than you could ever realistically

• hope to know well, at a given moment.

• If a video has more than 100,000 views from different people, more people have seen that

• video than you will ever meet in your life. And by meet, I mean shakes hands with, learn

• their name, talk with them for a bit.

• I mean, think of it this way: you and me, we're only statistically expected to live

• around 28,470 days. So, even if you were to meet someone, 2-3 people every day of your life

• (including when you were a baby), you still wouldn't meet as many people as have seen

• that YouTube video with 100,000 views.

• But, keep this in mind: even though you, or even a large group of us, can't do much to

• change Earth's location or rotation, we can affect it a little bit. Newton's Third Law

• guarantees this. If you weigh 150 pounds, the Earth is pulling you down with a force

• of 150 pounds. But, you are also pulling up on the Earth with a force of 150 pounds.

• If you fall 3 meters, the Earth has pulled you down 3 meters. But, you have also exerted

• an equal and opposite force on the Earth. Of course, it's a lot bigger. So, if you fall

• 3 meters, you pull the Earth up about one-billionth of the width of a Proton...which ain't bad?

• you just affected the Earth as much as it affected you. You've got that kind of power.

• Speaking of power, you all should go check out "Geek & Sundry", Felicia's new channel.

• It's one of my new favorite things...And, as always, thanks for watching.

Hey, Vsauce, Michael here, and what if every single person on Earth jumped at the exact

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# What If Everyone JUMPED At Once?

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榮得傑 posted on 2014/04/09
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