What is a vacuum? Detailed answer

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What is a vacuum? Detailed answer

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What is a vacuum?

Most people think that a vacuum is a space in which there is absolutely nothing. However, according to scientists, this is simply impossible. They believe that there is no such place where there would be no matter at all: not a single molecule of gas or a particle of dust. So the vacuum is really a space where there is very little matter. Deep vacuum means its almost complete absence. However, the main role in this phrase is played by the word "almost".

One of the simplest ways to obtain a vacuum is to pump air out of the vessel in which it is created. Currently, there are sufficiently powerful pumps capable of creating a very deep vacuum, which is necessary for both scientific and various industrial purposes. Such pumps, for example, create a vacuum in light bulbs during their manufacture.

If the light bulb contained oxygen contained in the air, then when it was turned on, the filament would burn out in a fraction of a second. In the most modern light bulbs, it is possible to pump out almost all the air with the help of vacuum pumps. The same can be said about vacuum tubes in televisions or radios, in which as much air as possible is sucked out before sealing.

Another well-known item that uses a vacuum is an ordinary thermos. It has double walls, a vacuum is created in the gap between them. Since the number of gas molecules in this space is small, they are at a great distance from each other, and thus the heat transfer between them is reduced. Therefore, if you pour cold milk into a thermos on a hot summer day, it will remain cold. And vice versa, hot tea will not cool down in a thermos, even in the most frosty weather.

Author: Likum A.

Random interesting fact from the Great Encyclopedia:

How is paper made?

Paper is made up of millions of tiny fibers. These fibers are cellulose, a substance derived from the fiber of various plants. The cellulose used today to make paper is made primarily from wood. After the log is stripped of its bark, the tree is ready to be turned into wood pulp, either by milling or by treating it with chemicals.

Some wood pulp manufacturing methods involve both milling and chemical processing. Then this mass is sieved and washed, thereby clearing it of dirt and chemicals. It can then be bleached to make characters printed or written on it more visible.

At the next stage, this mass is whipped in a special machine and mixed with water. The whipping process frays the fibers, turning them into a sticky, uniform mass. To improve the surface of the paper, make it more suitable for writing and printing, starch, clay and other materials can be added to the mass. Then the wood pulp enters the refiner, where the fibers are put in order.

At this stage, the mass is ninety-nine percent water and only one percent cellulose fibers. Now she is ready to enter the paper machine. In this machine, water leaves the mass through a sieve, and then the remaining water is removed using a suction pump.

The sieve vibrates, helping the fibers to adhere to each other. Then the wet mass passes under a round roller, which compresses it into a smooth sheet. This sheet is passed under a series of smoothing rollers that squeeze the water out of the sheet and make the paper thick and smooth. After that, it passes through a series of heated cylinders called dryers. At this stage, special coatings can be added to make the paper smooth and shiny. Paper comes out of these machines in the form of large rolls. Then it is trimmed, cutting off the rough edges and giving the roll the desired width.

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Scientists have said that singing can increase life expectancy by lowering blood pressure and promoting brain health. Singing also reduces the risk of dementia and helps fight depression. This discovery was made by experts from Yale and Harvard universities, USA

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