Question 2: What is a vacuum? Vacuum is a space without air. Looking around, we can see that vacuum packaging bags, thermos bottles, light bulbs and so on are all products that use vacuum.
In fact, there is a great mystery hidden in a vacuum. In the microscopic world that can't be smaller, many elementary particles can fly out of a vacuum and have nothing. There are countless such elementary particles, which are generated in a hurry and then disappear. Vacuum is by no means a "static" space with nothing in our imagination. On the contrary, vacuum is a place where intense activities are taking place, and it is an incredible unfamiliar environment.
To understand what vacuum is, we must deal with two difficult problems: the nature of matter and how the universe evolves. Exploring the essence of vacuum belongs to the frontier subject of modern science. Now, let's embark on a scientific journey to explore the mysterious nature of vacuum!
Is vacuum really "nothing"?
Let's go to the vacuum environment to test it on the spot, from the "low pressure" vacuum to the vacuum that produces basic particles.
Usually, we say that space is a vacuum without air. The word vacuum literally means "completely empty", "empty" and nothing. However, a field survey of the space near the orbit of the space shuttle shows that there is still thin air there. Even in the vacuum packaging bag and the inner container of the thermos bottle, there is nothing. No matter what method we adopt, we can't make our so-called vacuum really "completely devoid of air". What we call vacuum is nothing more than a "space with extremely thin air".
So, we need to know what "thin air" means. We know that air is mainly composed of oxygen molecules and nitrogen molecules, and these molecules are always flying around. For example, air at standard atmospheric pressure contains 10 19 molecules per cubic centimeter. That is to say, in a space the size of a dice, there are 1 trillion times as many unknown molecules as1billion times flying around. There are so many molecules in the air that it is obviously inconvenient to use the number of molecules contained to indicate whether the air is dense or thin. Usually, we use air pressure to express the density of air.
Next, let's look at the air pressure in the closed container. The gas molecules flying around in the container have been hitting the container wall frequently, and the trend is to push the container wall outward. The force generated by a single molecule hitting the device wall can naturally be ignored, but the number of molecules hitting the wall at the same time is often huge, and together it is a huge force. This thrust is air pressure. The essence of air pressure is that the thinner the air in the container is under the condition of constant temperature and volume, that is to say, the less the number of gas molecules in the container, the lower the air pressure. In the natural environment, the higher the altitude, the lower the air pressure. In other words, the higher you go, the closer you get to a "completely empty" vacuum.
This raises a question: to what extent can the pressure be said to be a vacuum? According to industrial standards, vacuum is by no means a "complete vacuum", but a "state in which the space is filled with gas below the standard atmospheric pressure". It can be seen that the vacuum mentioned in the industrial field is far from the "completely empty" vacuum we usually imagine.
Not only that, there is another kind of "vacuum" with different meanings, that is, the reality of the very, very small elementary particle world is simply beyond our imagination. In this regard, we will leave it to the second half of this article to make a detailed introduction. Here, let's first review the history of human exploration of vacuum.
Question 3: What does the network term vacuum mean? There's nothing on it.
Question 4: What is a vacuum? Vacuum degree? How many representatives are there? Vacuum refers to the gas state in which the pressure in a given space is lower than 10 1325 Pascal (that is, the standard atmospheric pressure is about 10 1KPa). Vacuum = atmospheric pressure-absolute pressure
As the name implies, vacuum degree is the degree of vacuum. It is the main parameter of vacuum pumping equipment such as vacuum pump, micro vacuum pump, micro air pump, micro suction pump and micro suction pump. The definition of vacuum degree is absolute gas pressure. The microscopic formula of pressure tells us that pressure depends on the number density of gas molecules and the average speed of thermal motion, which can reflect the vacuum degree of the system. The higher the vacuum degree, the lower the absolute pressure, which is usually expressed by "high vacuum degree" and "low vacuum degree". High vacuum degree means "good" vacuum degree, and low vacuum degree means "poor" vacuum degree.
There are usually two ways to identify the degree of vacuum:
First, it is marked by "absolute pressure" and "absolute vacuum" (that is, how much pressure is higher than "theoretical vacuum");
In practice, the absolute pressure of vacuum pump is between 0 ~ 10 1.325 kPa. The absolute pressure value needs to be measured by an absolute pressure gauge. Under the conditions of 20℃ and altitude = 0, the initial value of the instrument (absolute vacuum gauge) used to measure the vacuum degree is 10 1.325KPa (i.e. a standard atmospheric pressure).
The second is to distinguish between "relative pressure" and "relative vacuum" (that is, how much pressure is lower than "atmospheric pressure").
Relative vacuum refers to the difference between the pressure of the measured object and the atmospheric pressure of the measuring place. Measure with a common vacuum gauge. In the absence of vacuum (that is, under normal pressure), the initial value of the table is 0. When vacuum is measured, its value is between 0 and-10 1.325 kPa (generally expressed as a negative number).
Question 5: What is vacuum energy? Professor Gog's report was completed in one breath, and * * * followed. Professor Gao systematically expounded the extraction and purification of vacuum energy and dark energy.
The research will have a far-reaching impact on human life, especially on the upcoming breakthrough in aviation propulsion technology.
He also specifically talked about the spirit of scholarship and placed high hopes on the young students of Beihang University.
1 vacuum
What is a vacuum? Is there nothing in the vacuum? 100 years ago, a physicist predicted: charging in vacuum.
Energetic and inexhaustible. At the academic conference in Petersburg a few decades ago, the discussion about the vacuum problem
Scientists such as Mendeleev, Sir Kelvin and Tesla were wrongly labeled as pseudo-scientists. Tesla
He has a deep study of electromagnetic waves. He studied the scalar part of electromagnetic wave and successfully realized wireless current transmission. he
It is believed that there is ether in a vacuum. In the following years, the theory of ether was rejected. Now, the study of ether
There is a revival because people do extract energy from a vacuum.
Dr. Li Zhengdao also believes that vacuum is the solidified state of the medium.
Some scientists think that vacuum is an inexhaustible sea of energy.
1998, NASA incorporated the research of vacuum energy into its research plan. At that time, the US Department of Energy strongly opposed and recognized it.
Because it is impossible to extract energy from a vacuum without anything, it claims that it will not give any NASA information about vacuum energy.
Funding for research projects. Two years later, the US Department of Energy also included vacuum energy in its research plan.
In 2000, scientists put forward two slogans:
"The 20th century is the century of nuclear energy, and the century of 2 1 is the century of vacuum energy."
"The vacuum energy engine will be built in five years."
In fact, the United States made a device to extract vacuum energy in 1984, but most of the devices at that time were electromagnetic.
Equipment. They input energy of 1 and output energy exceeding 1. From the initial input/output = 1/4 to the current output.
Input/output = 1/20. The use of vacuum energy really realizes one sentence: the horse should run, not eat.
Grass.
But vacuum energy and perpetual motion machine are not the same concept.
When did fish know about the existence of water? It was when he was caught without water that he realized that he was still alive.
In the water. People live in the ocean of vacuum energy without realizing it.
Vacuum energy can be extracted by electrochemical method and fluid vortex method. Scientists in Petersburg, Russia, created a whirlpool.
The vortex pumping vacuum energy machine can reach 500 watts.
Scientists believe that the distance between atoms is as far as the distance between planets. When neutrinos want to
When crossing, it is like light crossing between planets. Then the gap between particles is a vacuum. This vacuum is almost
Reading has a strong impact on the traditional concept of vacuum.
In fact, vacuum can reveal many clues in experiments. In the past, many experiments that were considered as failures were actually vacuum.
The manifestation of energy. For example, thermal testing, in a closed system, produces an efficiency of more than 100%. Once the aero-engine
Using the world's vacuum energy, space flight will no longer need fuel, and power generation will not need fuel. At a diameter of 50 meters,
Under the action of a 200-meter-high vacuum energy generator, the energy it generates will be no less than that of the Three Gorges Hydropower Station.
It is a pollution-free energy source.
2. Dark matter and dark energy
1998, astronomers found that visible matter in the universe only accounts for 4% of all matter in the universe. 6% and the other 95%. 4% content
Both mass and energy are invisible. The mass of the planet measured by optical method is the mass measured by dynamic method.
00 years 1. From this, scientists have concluded that at least 90% of the matter in the universe is invisible. This substance does not attract people.
Light, which does not reflect or respond to light, is dark matter.
The simplest dark matter is quarks. Dark matter does not reflect or absorb light, and there is a weak interaction between substances. When the temperature
When it decreases, the attraction decreases, and when the temperature increases, the cohesion increases.
In 2002, CERN successfully produced 50,000 antihydrogen atoms. The collision of antiprotons and positrons will produce 10.
Trillions of energy released by hydrogen bombs. 2 1 century, antimatter energy will also appear in black and pink. In such a huge amount of energy
Driven by the amount, the people in the spacecraft can't bear it without the protection of the anti-gravity system.
Year 200 1, ... >>
Question 6: What is the vacuum degree? In theory, there is no matter in the volume, but there is no real vacuum in reality. Usually, the pressure in the container is lower than the normal atmospheric pressure (10 1325Pa), which is called vacuum state.
Vacuum degree: refers to the pressure below normal atmospheric pressure (10 1325Pa). It is authoritative that Lanzhou Institute of Physics divides the vacuum state below normal atmospheric pressure into five types:
Low vacuum: 100000Pa- 100Pa.
Medium vacuum: 100 pa -0. 1Pa.
High vacuum: 0. 1Pa-0.0000 1Pa.
Ultra-high vacuum: 0.00001pa-0.000001pa
Extremely high vacuum: less than 0.0000000 1Pa.
Pa means pressure. Written writing and instrument display are as follows: for example, 100000Pa is written as 10E 5Pa (read as 10 to the fifth power Pa, usually read as 65438+ million pa); 0.0 1Pa is written as 10E -2Pa (read negative 2 of 10, usually read negative 2 of 1.0).
Question 7: Is vacuum a substance? Vacuum: The fantasy world of elementary particles should be "without any substance", but elementary particles are active in a vacuum! What is a vacuum? Is it nothingness, is it the universe ... In many people's minds, vacuum is a space without air. Looking around, we can see that vacuum packaging bags, thermos bottles, light bulbs and so on are all products that use vacuum. In fact, there is a great mystery hidden in a vacuum. In the microscopic world that can't be smaller, many elementary particles can fly out of a vacuum and have nothing. There are countless such elementary particles, which are generated in a hurry and then disappear. Vacuum is by no means a "static" space with nothing in our imagination. On the contrary, vacuum is a place where intense activities are taking place, and it is an incredible unfamiliar environment. To understand what vacuum is, we must deal with two difficult problems: the nature of matter and how the universe evolves. Exploring the essence of vacuum belongs to the frontier subject of modern science. Now, let's embark on a scientific journey to explore the mysterious nature of vacuum! Is vacuum really "nothing"? Let's go to the vacuum environment to test ..., from the "low pressure" vacuum to the vacuum that produces basic particles. Usually, we say that space is a vacuum without air. The word vacuum literally means "completely empty", "empty" and nothing. However, a field survey of the space near the orbit of the space shuttle found that there was still thin air there. Even in the vacuum packaging bag and the inner container of the thermos bottle, there is nothing. No matter what method we adopt, we can't make our so-called vacuum really "completely devoid of air". What we call vacuum is nothing more than a "space with extremely thin air". So, we need to know what "thin air" means. We know that air is mainly composed of oxygen molecules and nitrogen molecules, and these molecules are always flying around. For example, air at standard atmospheric pressure contains 10 19 molecules per cubic centimeter. That is to say, in a space the size of a dice, there are 1 trillion times as many unknown molecules as1billion times flying around. There are so many molecules in the air that it is obviously inconvenient to use the number of molecules contained to indicate whether the air is dense or thin. Usually, we use air pressure to express the density of air. Next, let's look at the air pressure in the closed container. The gas molecules flying around in the container have been hitting the container wall frequently, and the trend is to push the container wall outward. The force generated by a single molecule hitting the device wall can naturally be ignored, but the number of molecules hitting the wall at the same time is very large, which adds up to a great force. This thrust is air pressure. The essence of air pressure is that the thinner the air in the container is under the condition of constant temperature and volume, that is to say, the less the number of gas molecules in the container, the lower the air pressure. In the natural environment, the higher the altitude, the lower the air pressure. In other words, the higher you go, the closer you get to a "completely empty" vacuum. This raises a question: to what extent can the pressure be said to be a vacuum? According to industrial standards, vacuum is by no means a "complete vacuum", but a "state in which the space is filled with gas below the standard atmospheric pressure". It can be seen that the vacuum mentioned in the industrial field is far from the "completely empty" vacuum we usually imagine. Not only that, there is another kind of "vacuum" with different meanings, that is, the vacuum of the very, very small elementary particle world. The vacuum in the world of elementary particles is simply beyond our imagination. In this regard, we will leave it to the second half of this article to make a detailed introduction. Here, let's first review the history of human exploration of vacuum.
Question 8: What does a time vacuum mean? Newton thinks that there is an absolute vacuum in the universe, that is, there is no air, no rays, no field and no matter, so time there stops. Because there is no matter, there is no matter movement, and time is a parameter to record the movement of matter, so time there will accumulate second by second.
But later, after Einstein put forward the theory of relativity, he thought that there was no such absolute vacuum in the world, so there was no question you asked.
The World in the Shell and A Brief History of Time written by Hawking, a contemporary scientist, have a new view that time may have stopped before the Big Bang and after the universe returned to the black hole.
Question 9: What is vacuumizing? Vacuum is a state of space without any substance and a physical phenomenon. In "vacuum", because there is no medium, sound cannot spread, but the propagation of electromagnetic waves is not affected by vacuum. In fact, in vacuum technology, vacuum refers to the atmosphere, and some substances in a specific space are discharged to make its pressure less than a standard atmospheric pressure, so we generally call this space vacuum or vacuum state. 1 Vacuum usually uses Pascal or Torr as the pressure unit. At present, in the natural environment, only outer space can be called the space closest to vacuum.