Shulou(Shulou.com)11/24 Report--

The original title: "in order to weigh less, do not hesitate to dig and dig in the big earth." "

Trying to answer a stupid question can tell you about some serious science.

To lose 20 pounds (9.07kg), how much of the Earth's mass needs to be moved into space?

This is not simple, your weight comes from the earth's downward gravity, and the earth's gravity comes from its mass. The smaller the mass, the smaller the gravity, so remove the earth's mass and you can lose weight!

So you decided to give it a try.

It takes a lot of energy to remove a lot of mass from the earth, so you have to start by grabbing the entire planet's oil reserves. Professional operation, please do not imitate!

You first process oil into fuel and then use it to transport hundreds of billions of tons of rock into orbit, reducing the thickness of the rock layer on the earth's surface by an average of 0.2 millimeters.

And then you got on the scale with anticipation. 190 pounds.

Well, it doesn't work, but it makes sense: after all, hundreds of billions of tons are negligible relative to the total mass of the earth.

Then you think that burning other fossil fuels on the planet, especially the considerable reserves of coal, can also reduce the mass of the earth and allow you to remove about a millimeter of the thickness of the earth's surface.

After doing this, you are looking forward to getting on the scale again. Or 190 pounds?

Alas, you realize that more energy is needed.

Then you cover the whole planet with efficient solar panels and take a year to absorb all the sunlight that hits the earth to power your rock launcher. But humans will have to live in the shadow of solar panels as a result. People may be angry with you for this behavior.

A year's sun will provide you with enough energy to clear nearly 100 trillion tons of rock a few inches thick from the earth's surface. Unfortunately, this is far from enough.

Obviously, this gradual approach will not work.

You need more energy, and instead of capturing only a small portion of the solar energy that hits the earth, build an energy collection shell, the Dyson ball, directly around the sun. It can collect all the energy released by the sun. Once you control this energy, you can thin the earth's surface more quickly.

The deeper you dig, the hotter the rocks on the earth. When you peel off the earth's crust several hundred meters thick, people find that the ground is warming, and by the time you remove the rock layer of 1km, the surface has reached 40 degrees Celsius. When you get up on a cold morning, the hot ground may make your feet feel warm, but it can make life uncomfortable. In addition, because you have removed the tops of all geological hot spots (deep underground in the mantle, there are magma chambers filled with hot magma), all the volcanoes in the world will erupt.

You checked the numbers on the scale again. 190 pounds.

Alas!

You continue to remove more rocks with the Dyson ball, and it takes about 20 minutes to peel off the 5km thick rock layer (in addition, you can spend a few more minutes removing the ocean). The earth is no longer habitable, and northwest Wyoming has become a lava lake because of the magma exposed under the Yellowstone super volcano. In most places, the ground is hot enough to boil water and make a fire.

Try to get on the scale again.

It doesn't matter, you just need to remove more rocks, maybe you can try a solar-powered planetary peeler.

You cut off the thick crust of 20km, which exposes most of the former undersea mantle.

Well, no one ever said it was easy to lose weight. You have removed the Earth's 20km thickness and removed the molten mantle layer and the deep crust alien capsule.

You continue to refuel, and after four hours of hard work with a planetary peeler, you have removed most of the molten rock that is thick with Earth's 60km. When you step on the scale, you finally see the change. 191 pounds?

And you put on a pound.

How was this possible?

If the density of the earth is uniform, then removing the earth's shell will make you lighter, but our earth's density is not uniform, but as we dig deeper, the density increases, so the increase in density will offset the loss of mass. As you remove the surface, the planet becomes lighter and lighter, but you are also getting closer and closer to the dense core. The net effect is that removing the outer layer of the earth will make its surface gravity stronger.

Gravity increases with the depth of the earth you are in. Only after you cut off about 3000km, halving the earth's diameter and ejecting 2/3 of its mass will the gravity of the earth's surface stop increasing (which will take your solar planetary peeler a week). Your weight reaches a peak of 207 pounds, and then as you begin to remove the denser outer nuclei, you begin to lose weight.

Once you remove the 3450km rock, your weight will return to the beginning. After cutting off the thick rock layer of 3750km, you have finally achieved your goal of losing 20 pounds. So far, you have eliminated 85% of the earth's mass. You've lost weight!

The plan has some flaws. It destroyed the earth, and yes, it was unnecessarily inefficient. There is an easier way to reduce the earth's gravitational pull on you without changing the mass or leaving the surface.

The spherical shell of matter does not exert any gravity on the objects inside, which means that if you go down, the rock above you will not affect your weight. From a gravitational point of view, they seem to have disappeared. You don't actually need to remove matter from the earth, you just need to pass through it. You can avoid all the work with a relatively simple tunnel.

So did you at least avoid exercise? Yeah, sort of. Your project ultimately requires you to do a lot of work. Clearing the earth's surface requires more calories than all humans consume 24 hours a day of intense exercise from now on until the sun burns out and its residue cools to room temperature.

The number of calories needed to lose 20 pounds your plan 50000000000000000000000000000000000 other people's plan is less than the above figure. If your goal is to lose weight without exercise, you can't fail any worse than that.

Author: RANDALL MUNROE

Translation: depth

Revision: * 0

Original link: Lose Weight the Slow and Incredibly Way

This article comes from the official account of Wechat: Institute of Physics, Chinese Academy of Sciences (ID:cas-iop), author: RANDALL MUNROE

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