Does anyone know the reason for direct sunlight?

When Confucius traveled eastward, he saw two children arguing (1) and asked him why (2).

A son said, "I started from (3) the day I went out, (4) people were near, and Japanese and China were far away." Another child thinks that the sun is far from the sun when it rises, and it is closer to people at noon.

A son said, "When the sun rises, it is as big as a hood (6), and when it rises at noon (7), (8) is like a vegetable bowl (9). This is not (10) which is smaller and which is closer? "

A son said, "It's cool when the sun rises in the morning (1 1), just like exploring soup at noon (12). Isn't this near hot and far cold? "

Confucius can't decide (13). The two children laughed and said, "Who is smarter than you (15)?"

Precautions:

(1) Debate: Debate, debate.

(2) reason: reason, reason.

(3) take: think, think.

(4) Go: Leave.

(5) noon: noon.

(6) Car cover: The canopy on ancient cars was umbrella-shaped.

And: here we are.

(8) then: just.

(9) jar: an open vessel for holding wine and food.

(10) Yes: Yes.

(1 1) Cang Cang Liang: cold and cloudy, with cool weather.

(12) soup exploration: put your hand into hot water. It means it's very hot.

(13) judgment: ruling, judgment.

(14) who: who, which.

(15) ru: you.

This article is an allegorical story. The article describes that in ancient times, two children relied on their own intuition. One thinks that the sun is close to people in the morning, and the other thinks that the sun is close to people at noon. For this reason, they hold their own opinions and argue endlessly, even a knowledgeable person like Confucius can't make a judgment. This story shows that in order to understand nature and explore objective truth, we must dare to think independently and question boldly; It also shows that the universe is infinite and knowledge is infinite. Even the most knowledgeable people will know something and learn endlessly.

Light can stimulate the retina to produce radiant energy of visual ability; The visible spectrum range of electromagnetic wave is 380 ~ 770 nm (10-9m).

Divided into artificial light and natural light. We can see the ever-changing multi-tone scene in the objective world because our eyes receive the light emitted, reflected or scattered by objects. Light is closely related to human life and social practice.

Strictly speaking, light is a kind of radiation that can be observed by human eyes. Experiments show that light is electromagnetic radiation, and the wavelength range of this part of electromagnetic wave is about 0.77 micron of red light to 0.39 micron of purple light. Electromagnetic waves with a wavelength of more than 0.77 micron to about 1000 micron are called "infrared rays". Below 0.39 micron to about 0.04 micron is called "ultraviolet". Infrared and ultraviolet rays can't cause vision, but the existence of this luminous object can be measured and detected by optical instruments or photography. Therefore, the concept of light in optics can also be extended to infrared and ultraviolet fields. Even X-rays are considered as light, and the spectrum of visible light is only a part of the electromagnetic spectrum.

Light has wave-particle duality, that is, it can be regarded as a kind of high-frequency electromagnetic wave (10/2 ~1015hz), and it can also be regarded as a particle, that is, photon for short.

The speed of light replaced the platinum watch kept in the International Bureau of Metrology in Paris as the standard for defining "meter", and it was agreed that the speed of light was strictly equal to 299,792,458 m/s, which was consistent with the definition of meter and second at that time. Later, with the continuous improvement of the experimental accuracy, the numerical value of the speed of light changed, and the meter was defined as the distance traveled by light in 1/299792458 seconds.

Light is one of the sources of life on earth.

Light is the foundation of human life. Light is a tool for human beings to know the outside world. Light is an ideal carrier or media of information.

According to statistics, at least 90% of all information received by human senses from the outside world is transmitted through the eyes. ...

Light is essentially an electromagnetic wave, covering a wide electromagnetic spectrum (from X-ray to far infrared), but its wavelength is shorter than ordinary radio waves. Visible light visible to the naked eye is only a part of the whole electromagnetic spectrum.

When a beam of light is projected on an object, it will be reflected, refracted, interfered and diffracted.

Light waves, including infrared rays, have shorter wavelengths and higher frequencies than microwaves. Therefore, it is a natural and inevitable trend to develop from microwave communication in electrical communication to optical communication.

Ordinary light: Generally speaking, light is composed of many photons. Under fluorescence (ordinary sunlight, light, candlelight, etc.). ), there is no connection between photons, that is, different wavelengths, different phases, different polarization directions and different propagation directions, just like an unorganized and undisciplined photon army, all photons are stragglers and cannot act in unison.

Laser —— A New World of Optics

In a laser beam, all photons are interrelated, that is, they have the same frequency (or wavelength), phase, polarization direction and propagation direction. Laser is like a disciplined photon army, acting in unison, so it has strong combat effectiveness. This is the main reason why laser can do many things, but sunlight, light and candlelight can't.