At present, the main energy source of human beings is oil and coal. They are ancient dead animals and plants in the sun after millions of years to form. They are non-renewable energy. That is to say, the earth's resources will be exhausted one day.
So people always want to have a machine, as long as give it an initial motivation, it can keep movement, a steady stream of energy for human creation, people will be this kind of machine is called the "perpetual motion machine", for hundreds of years scientists have been hard for its, because once created a perpetual motion machine, can bring significant economic benefits, fundamentally solve the energy problem, Even human society has changed significantly.
Later, however, not only did not produce a perpetual motion machine, but also accidentally discovered the law of conservation of energy, that is, in a closed system, the total energy remains the same, it will neither disappear, nor appear, which fundamentally denied the possibility of the existence of perpetual motion machine 39bet-xsmb-xổ số tây ninh-xổ số binh phước-xổ số binh dương-xổ số đồng nai.
But since the birth of the earth began to spin, it has been 4.6 billion years, and there is no sign of stopping, so is the Earth not a perpetual motion machine?
Where does it get its energy from?
In the universe, there are no absolutely stationary stars, and there are no completely non-rotating planets. They may be fast or slow, but can not be stationary. For example, although the moon does not appear to spin, it is actually locked by the Earth's gravitational tides. If the Earth suddenly disappeared, the moon will still turn.
If these planets could spin their enormous bodies for billions of years, wouldn't they be perpetual motion machines?
The earth is affected by the sun's gravity, so there will be a cycle of 365 days of revolution, also have four seasons, that the earth itself rotates of energy from where?
We can't seem to find the source of power for the Earth's rotation for a while.
Scientists have several hypotheses
Some people believe that the earth is self-rotating, that is, it provides its own energy, the earth as a whole can be divided into three layers: the crust, the mantle and the core.
The Earth's crust is composed of rocks composed of minerals, while the mantle is composed of some ultrabasic rocks and liquid magma, with the focus on the core. The temperature of the core can reach 4000-6000℃. Iron and nickel become extremely dense liquid under high temperature and pressure, and a large number of radioactive elements exist in the core.
These elements continue to decay, releasing huge amounts of energy that keeps the liquid iron and nickel spinning around the core, and as it spins, friction forces the entire Earth.
Although this hypothesis sounds reasonable, it actually has a loophole. According to the existing fossil inference, in the Devonian period more than 400 million years ago, a day was only 20 hours long. The earlier the day was, the faster the Earth's rotation was, indicating that the Earth's rotation was gradually slowing down.
Since the Earth's core is not cooling, the Earth's rotation time should remain within a stable range, suggesting that the core may not be the source of energy for the Earth's rotation. This gradual decline in rotation speed is more like a gradual decline after an initial speed.
So the angular momentum theory takes over
4.6 billion years ago, the solar system had not yet formed, only the remains of the last supernova that exploded late in life. Some of the larger pieces of nebula begin to pull material from their surroundings towards them under the influence of gravity.
As the central material tightened, it became denser, hotter and more pressurized, and eventually formed the young sun. After the formation of the sun, a small amount of debris was left behind, and some of the larger debris regrouped with the surrounding material, and the Earth began to form.
Confusion of the early solar system, various pieces of meteorite hit back and forth, the earth is not exceptional also, permanently meteorites and asteroids crash, one of the biggest stars even reached the size of Mars, the impact for the first stationary earth provides initial angular momentum, and the universe is a vacuum environment, almost no friction, so the earth's rotation lasted so long.
But if there is almost no resistance in the vacuum, why is the Earth's rotation slowing down?
By far, the biggest impact is likely to come from the moon, the Earth's only natural satellite. At their most recent, the moon is only 300,000 kilometers away, and the Earth's enormous gravity causes the moon to be tidally locked, with only one side facing the Earth at all times.
Also will be on the earth's gravity, the moon and the earth tide, the sea of the changing of the tides, friction and earth's rotation direction of the sea at the bottom of the sea. By contrast, it consumes some of the earth's angular momentum, other space junk, and launch satellites, which also can cause friction with the atmosphere, reducing the speed of the earth's rotation.
If the earth stopped spinning one day, human beings would be in danger. Although the earth has stopped spinning, the inertia of the atmosphere will keep it moving in the original direction. Then the fierce friction between the atmosphere and the ground will blow everything off the ground. Then the ocean will continue to flow in the direction of its rotation, and finally a super tsunami will hit the land.
And the earth always has only one side facing the sun, the other side is always left in the cold night.
But for now, even though the Earth's rotation is slowing down, there's a good chance that it won't stop completely, that the Earth's angular momentum won't return to zero, but will approach zero indefinitely, eventually spinning at a very slow rate.
To that extent, the solar system might not even exist by then.