10 questions you really need to know the answer

Here are 10 questions that even young adults have ever wondered, but do we all know the answer?

Americans, invested every year in scientific research up to $ 60 billion, feel ashamed to be unable to answer questions about basic scientific knowledge.

A 2009 survey, Harris Interactive, found that only 53% of Americans surveyed correctly answered "the earth took a year to turn around the sun" , and only 59% knew the first and terrible human species long appears in the same age. 47% answered exactly 70% of the earth's surface covered with water. And only one in five adults in the US surveyed can answer all of these questions correctly.

A 2011 University of Michigan study found that only 28% of American adults in the United States had enough scientific knowledge to be able to read and understand the " third day science " section of the New York Times. , up from 10% according to the 1988 survey.

It is not clear how these statistics will change if conducted in Vietnam. Science is an endless road with thousands of turns, obviously, you cannot become a scientist in just a few days.

We will help you get an overview through 10 basic questions that everyone must know how to answer.

1. Why is the sky blue?

The reason why the sky is blue is because of a phenomenon that we call dispersion . Sunlight passing through the earth's atmosphere is blocked, reflecting light everywhere. If you've ever observed light passing through a prism, you'll see that the light emitted from the sun consists of many colors, each with a different wavelength . Blue light has a relatively short wavelength, so the molecules in the air disperse it around, staining the sky into blue. Meanwhile red light has a longer wavelength, so it is more active and not so dispersed. This explains that during the day when the sun is high, the sky is always blue.

At dawn and sunset, sunlight does not go straight but must go a farther way to reach the human eye. At that time the wavelength of light was scattered and the human eye could only see light with a long wavelength, which is why at dusk and dawn we often see the sky red, orange and gold.

2. How old is our earth?

Earth's longevity is a controversial issue for centuries. Back in 1654, a scholar named John Lightfoot, the author of calculations based on "The Book of Genesis" , claimed that the earth was created at 9 am (Mesopotamia), on the 26th. / 10/4004 BC. In the late 1700s, the scientist named Comte de Buffo, from the experiment of the cooling of the globe, estimated the earth to be about 75,000 years old. In the nineteenth century, physicist Lord Kelvin used different equations to calculate the age of the earth for 20-40 million years.

But superiority is the assumption in the late nineteenth and early twentieth centuries, by the detection of scattering. Earth scientists have used that knowledge to determine the age of the rocks on earth, as well as meteorite and rock samples brought back from the moon by astronauts. Since then, scientists have been able to determine that the earth formed about 4.54 billion years ago with 1% uncertainty.

3. How does natural selection take place?

Like the assumptions about the life expectancy of the earth, evolutionary theory - first developed by biologist Charles Darwin in the mid-nineteenth century - is also another controversial topic. In the classic film "Inherit the Wind" , a biology teacher named John Scopes was accused of violating the "Tennessee" act (a law that forbids anyone to say that people have origin from lower animals). In recent years, there have been groups of people fighting the court to demand that science subjects be introduced, and the theory of evolution into children's educational environment.

Darwin's natural selection is not really a confusing idea. In nature, mutations are concepts that indicate the ability to develop other abilities from an ancestor that appear randomly. However, evolution is a long process in which animals and plants change over generations . Instead, changes in organisms tend to become more common over time if changes help organisms survive and reproduce better.

For example, some hard-winged species are green, and then mutations help brown species. Brown beetles are easier to disguise in nature than blue beetles. They will continue to survive and produce brown beetles and then, overcome the genetic change that their children will be brown.

In fact, natural selection is based on average levels, not a specific individual and is not necessarily favorable or in a regulatory order.

4. Does the sun ever stop lighting?

The question reminds us of Skeeter Davis ' song "The End of The World" . In the lyrics the singer wondered why the sun was still shining when her lover seemed to have left her. The lyrics in the song are the reality around us: whether the sun is still shining or the bird is still singing on the branches - all are stronger than the fragile emotions in every human being. Even though the lost girl in the song felt unhappy to be born too soon - about 5.5 billion years - all received or lost something in her life. It was at a time when the sun, like so many other stars, was a giant fusion reactor that would be depleted of hydrogen gas in the core to burn like fuel to produce sunlight and begin. burning hydrogen in layers around it.

It was the beginning of the death of the sun in which the sun's core would shrink and its outer layers would grow terribly, turning the sun into a giant red planet. In the last blast, the sun will "turn nine" the solar system with a heat explosion , turning even the most frequent icy areas of Pluto and Kuiper belt (formerly known as Neptune) into one Sauna oven. It is possible that planets in the solar system (including the earth) will also be swept into this fiery planet or turned into ash.

Unless humans find another planet to hide, no one wants to stay to experience this ultimate hell. The sun at about half of its expected life has gradually warmed up, and a million years later from now, the sun will be about 10% brighter now. That increase in solar radiation is enough to boil all the oceans on our planet.

5. How does the magnet work?

Magnets are objects that can absorb and push objects with iron or young steel . In magnetism, a magnet is an object capable of producing a force used to attract or push a magnetic object or object with a high magnetic susceptibility when located near a magnet. The force generated from the magnet is called magnetic force .

Magnets are a magnetic source with two poles: North and South, and a magnetic field created from the lines of force going from the North to the South.

Inside a magnet there are always tiny particles of metal from the magnet. Each of them acts as an individual magnet. In an industrial magnet, these particles align. That's why if we cut a magnet in half, we get two separate magnets, and so on.

A metal material with an iron substrate is always contained within magnetic particles (called magnets) but they have different orientations. Therefore, the general magnetism is annihilated. If we align these particles with a magnet, after a while the material will be infected.

6. Why is there a rainbow

Rainbow is a beautiful natural phenomenon. When science has not yet developed, the rainbow has also made people believe that when a rainbow appears hidden and miraculous. In the Bible of the Christian Bible, it is recorded that God placed a rainbow in the sky after the Great Flood and told Noah that "this is a sign of a new covenant between God and the Earth." ". As for the ancient Greeks, they believed that the rainbow was the goddess Iris. And over the centuries, various great scientific ideas from Aristotle to Rene Descartes have all sought to explain this beautiful rainbow phenomenon.

Basically, rainbows are created by water droplets suspended in the air after a rain. Water droplets have a density greater than the density of the surrounding air molecules, we know that sunlight goes straight but will be skewed when crossing the boundary of substances of different density so when light the sun shines through them, they are like small prisms, bending light. That is the phenomenon of refraction . Thus the droplets in the air can refract the sun's rays, but on the condition that the sun's rays must encounter drops of water at a relatively small angle, called the angle of deviation of the rainbow (about 40 degrees compared to ground).

That explains why we see the round bridge in the morning or afternoon, never at noon. It is interesting when you see the rainbow while on the plane, you will see that it has a disk image rather than an arc.

7. What is relativity?

Albert Einstein 's theory of relativity consists of two physical theories of special relativity and general relativity . Einstein gave a very clever example to explain this theory: "When a man sits next to a beautiful woman for an hour, it is no different from a minute. But let him sit next to him. a huge fire, one minute for him is longer than ever. " That is the theory of relativity.

Before Einstein, people believed that time and space are fixed, cannot be changed because that is how they see people from the vantage point of people on the ground. But Einstein used mathematics to prove that absolute points were purely illusions. He explained that space and time can undergo transformations: space can shrink, stretch or bend, and the rate at which time lapse can change as well as if There is an object affected by a strong gravitational field or the object is moved very quickly.

The Global Positioning System (GPS) with satellites depends on an accurate measurement of the time it takes to provide a map position on the earth as an example. The satellites are moving very fast around the earth at a speed of about 14,000 km / hour and if the space engineers do not adjust their hours to compensate the relative amount, within a day, Google Maps on the phone will Give us positions 9.86km from the actual position.

8. Why is bubble foam shaped?

In fact, if you've ever played soap bubbles , you'll see bubble bubbles aren't always round. When it starts to blow, bubble bubbles take a long, long shape, and for spherical bubbles, bubbles must reshape themselves. That's because bubble bubbles have a thin layer of liquid in which molecules stick together by gravitation, this phenomenon called cohesion.

This creates a thin film that we call surface tension , forming a barrier against elements that try to pass through it. Inside the thin film, trapped air molecules cannot move outside, even when they try to push water particles out. But not only water molecules work on that surface. Outside, other air molecules are also trying to pass through the membrane. The most effective way for this thin film to withstand the penetration of air molecules is to form the smallest possible sphere.

It is interesting that scientists have found a way to make bubble bubbles look different in spherical shape, helping to study the geometry of the surface. They can create a cube-shaped bubble, even a rectangle, by hanging a thin layer of liquid on a wire frame molded into the desired shape.

9. What is the word cloud?

The cloud is a large array of water droplets, ice crystals , or a mixture of both when they float above the surface of the earth.

Clouds are formed when humidity and air pressure in the air increase. When it rises, reaches a cooler temperature, the air humidity drops, the steam condenses into droplets, or into ice crystals, depending on the temperature they encounter. These drops of water and ice crystals gather together on the principle of cohesion. The result is the creation of the cloud. Some clouds are larger in shape than other clouds because they form in areas with a higher density of water droplets.

Clouds are an important component of the hydrological cycle on our planet, in which water is constantly moving between the surface and the atmosphere, which is transformed from liquid to vapor, then into liquid, double when it is solid. Without the clouds for this cycle, there will be no life on our planet.

10. Why does water evaporate at room temperature?

In fact, when you see water in molecular form , their activity is like a bunch of puppies crowding in their nest. So are water molecules, they try to collide, win each other's position. When there is a lot of water vapor in the air, surface water molecules will fly up and stick to them, which explains the condensation outside of a cold drink on a wet day.

Conversely, if the air is drier, the water molecules in a glass of water can get hit by the air and get caught in other molecules that are floating around. This process is called evaporation. If the air is dry enough, more water molecules will evaporate from the glass. Over time, the glass of water will gradually lose water molecules and end with a glass of water running out.

The ability of liquid molecules to be pushed into the air and attached is called vapor pressure , because the molecules evaporate from applying a green as a gas or a solid. Different liquids have slightly different pressures. Liquid as acetone that women still use to remove nail polish has a very high yield, meaning it is easy to evaporate and go into the air. In contrast, olive oil has an extremely low vapor pressure, so it is almost impossible to evaporate at room temperature.