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Light travels fast. In fact, light is the fastest thing known to travel, and there is a law in physics that nothing travels faster than light. Light travels at a speed of 300000 kilometers per second, from the earth to the moon in a little more than a second, or from Los Angeles to New York in less than a blink of an eye. Miraculously, the fastest and slowest speeds in human life are related to light.

Can we make an object that moves at the speed of 1% of light?

Although 1% may not sound like much, 1% of it is still very fast for the speed of light-it moves about 10 million kilometers per hour! At 1% of the speed of light, the journey from Los Angeles to New York takes a little more than a second, which is more than 10,000 times faster than a commercial plane.

The Parker solar detector is the fastest object ever made. It uses the sun's gravity to speed up to 0.05% of the speed of light. NASA / Johns Hopkins APL / Steve Gribben the fastest thing man has ever made, bullets can reach speeds of up to 4200 kilometers per hour, more than three times the speed of sound. The fastest plane is the NASA X3 jet, with a top speed of 11200 kilometers per hour, which is impressive, but only 0.001 per cent of the speed of light.

The fastest man-made object is the spaceship. They use rockets to escape the earth's gravity and can reach speeds of up to 40000 kilometers per hour. The fastest spacecraft is NASA's Parker Solar probe. After launching from Earth in 2018, it skimmed the sun's scorching atmosphere and reached a speed of 535000 kilometers per hour using the sun's gravity. This is a very fast speed-but only 0.05% of the speed of light.

Why is it difficult to reach 1% of the speed of light?

What prevents humans from reaching 1% of the speed of light? Simply put, it's energy. An object will have corresponding energy because of its motion, which physicists call kinetic energy. In order to run faster, you need to increase your kinetic energy. The problem is that to increase the speed to a very high level, you need a lot of kinetic energy. It takes four times the energy to make something run at twice the speed, nine times the energy to make it run at three times the speed, and so on.

For example, a youth weighing 50 kilograms needs to provide 200 trillion joules (a unit of energy measure) to reach 1% of the speed of light, which is about 2 million Americans a day.

Solar sails, this thin, shiny square on the Japanese IKAROS spacecraft, can propel the spacecraft to 10 percent of the speed of light. Andrzej Mirecki via Wikimedia Commons CC BY-SA, how fast can we move? It is possible to reach 1% of the speed of light, but it requires a lot of energy. Can humans make objects move faster?

The answer is yes! But engineers need to find new ways to make objects move in space. The fuel burned by all rockets is not much different from the gasoline used by cars, and the common problem they face is that the fuel burning efficiency is very low.

Other ways to propel a spaceship include the use of electricity or magnetism. The nuclear fusion process that provides energy to the sun is also more efficient in terms of energy use than chemical fuels.

Scientists are studying many other ways to run at high speeds-even warp engines, the superluminal travel that is popular in Star Trek.

One promising way to make objects move at high speed is to use solar sails, large, thin sheets of plastic attached to spaceships, so that the sun can push them like the wind on the sails. Some spacecraft have used solar sails to prove their feasibility, and scientists believe that solar sails can propel the spacecraft to 10 percent of the speed of light.

One day, when human speed is no longer limited to a small part of the speed of light, we may travel to other planets.

The slowest speed in the world is also related to light? The laser focuses a narrow, directional beam on a specific point, making it an important tool for cutting, combustion and welding. These activities generate or require heat. The laser beam travels at the speed of light at more than 670 million miles per hour, the fastest in the universe.

So how does a laser produce the slowest object on earth?

First of all, the key point is to understand the relationship between the temperature and velocity of an object. The higher the temperature of an object, the more energy it has and the faster it moves. Although some things seem to be completely static, such as a pen or your notebook, this is not the case. At the micro level, the particles that make up them are constantly moving at high speed, and so are life forms.

Let's take the famous slow animal "sloth" as an example. If you look at the molecules that make up the sloth's body with a microscope, you will see them bouncing around like children in a bouncing room. What causes it? About 70% of the body of a sloth is made up of water, and these water molecules jump around at hundreds of miles an hour.

Laser cooling it may come as a surprise that physicists interested in the behavior of atoms and molecules at very low temperatures use bright, high-intensity lasers to cool objects in their experiments. This is a strange world ruled by quantum mechanics. Believe it or not, particles sometimes behave like waves in the ocean and sometimes appear in two different places at the same time.

To study this novel behavior, physicists used lasers to create the coldest atomic clouds on earth, called Bose-Einstein condensates. Cool a bunch of atoms, and when the temperature approaches absolute zero, the atomic behavior begins to follow quantum mechanics and move in an amazing way.

The study of ultra-cold atomic clouds may provide clues to how other strange materials such as superconductors work. Superconductors can transmit electricity better than existing materials and may one day be used to build ultra-high-speed trains.

In 1995, researchers cooled atoms to lower levels than ever before and created new states of matter as predicted by Albert Albert Einstein. This picture shows a snapshot of atoms condensing from more scattered red, yellow, and green regions into very dense blue and white regions. NIST / JILA / CU-Boulder creates the slowest thing on Earth. So how on earth does a laser cool a bunch of atoms? In the laboratory, we first irradiate a silver metal atom called ytterbium with a laser. These very hot atoms are placed in a 1-foot-wide cavity. After a few seconds of exposure to the laser beam, they cool, slow down and be tied to the center of the chamber.

How did this happen?

All light, including lasers, is made up of photons, which are constantly moving packets of energy. When we shoot a laser into the room, the atom collides with the photon flow in the beam, slows down and lowers the temperature-just like what happens when you run fast in a strong wind.

These tiny collisions lower the temperature of the atomic cloud to one millionth above absolute zero.

But that's not enough to make atomic clouds the slowest matter on earth. A final step is needed to make it a little colder, which physicists call "evaporative cooling".

First, we capture all the atoms and sometimes use the magnetic field generated by the electrified coil to form a "well" that can hold the atoms but is invisible: just like marbles gather at the bottom of the bowl. The sides of the bowl-shaped force field are then lowered by reducing the current passing through the wire, allowing faster, hotter atoms to escape from the bowl.

Only the slower atoms fall behind-and these atoms are really frozen: they are one thousandth higher than absolute zero. Atoms in cold atomic clouds move very slowly: if they move in a straight line instead of bouncing around, it takes a whole hour to cross a room at their rate. By contrast, the molecules in your body can rush through that room in as little as a second.

The atoms in the cold atomic cloud, which is the slowest moving matter on earth, move more slowly than snails.

Original text link:

Https://theconversation.com/have-we-made-an-object-that-could-travel-1-the-speed-of-light-170849

Https://theconversation.com/what-is-the-slowest-thing-on-earth-132827

The content of the translation only represents the author's point of view, not the position of the Institute of Physics of the Chinese Academy of Sciences.

This article comes from the official account of Wechat: Institute of Physics, Chinese Academy of Sciences (ID:cas-iop), author: Impey&McCormick, translator: Crunc, revision: zhenni

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