What is a line blue shift and a line red shift?

Redshift and blueshift are observations of the movement of stars in astronomy. As the stars move farther and farther away from us, there is a shift in color in the direction of red light, and vice versa, a shift in color in the direction of blue. These phenomena are known as red symmetry and blue shift.

Details are discussed below.

When astronomers began to look at the spectra of stars in other galaxies in the 20s, they discovered the most bizarre phenomenon: they had the same absorbent characteristic line families as our own galaxy, except that all of them moved by the same relative amount towards the red end of the spectrum. In order to understand this implication, we must first understand the Doppler effect.

We already know that visible light is the undulation or fluctuation of an electromagnetic field with a frequency (or number of vibrations per second) of 4 to 7 trillion vibrations.

For different frequencies of light, the human eye appears to be different colors, with the lowest frequency appearing at the red end of the spectrum and the highest frequency at the blue end. Imagine that a light source – such as a star – at a fixed distance from us emits light waves at a fixed frequency, and it is clear that the wave we receive is of the same frequency as it was emitted (the gravitational field of a galaxy is not strong enough to have a noticeable effect on it). Now suppose that the stellar light source starts to move towards us, and when the light source emits a second crest, it moves closer to us, so that the crest takes less time to reach us than it would if the star was still.

This means that the time interval between these two peaks reaching us becomes smaller, so the number of vibrations per second (frequency) of the waves we receive is higher than when the star is at rest. Similarly, if the light source moves away from us, the frequency of the wave we receive becomes lower. So for light, this means that when stars leave us, their spectrum shifts towards the red end (redshift);

And when a star comes closer to us, the spectrum shifts blue.

Redshift, when a light source approaches the observer, receives a decrease in frequency, equivalent to a shift to the red end, known as a "redshift".

Blue shift, when the light source approaches the observer, the acceptance frequency increases, which is equivalent to a shift to the blue end, which is called "blue shift".

Think about ultrasound in a similar sense, it's all mechanical waves.

I also looked it up on the Internet, but I don't understand it very clearly.

This is a fundamental physics problem: if a luminous object leaves the Earth at high speed (it must be tens of thousands of kilometers per second), then the light emitted by it that we detect it on the Earth will have a redshift--- mainly because its speed affects the wavelength of its spectrum.

Don't read Hawking's book, you can't understand it.

Redshift: Divided into gravitational redshift, cosmological redshift, and Doppler effect. The general features are:

The spectral lines of redshifted light move as a whole from the red side of visible light compared to the normal spectrum. In the field of physics and astronomy, redshift refers to the phenomenon that the electromagnetic radiation of an object increases in wavelength for some reason, and in the visible band, it is manifested as the spectral line of the spectrum shifts a certain distance towards the red end, that is, the wavelength becomes longer and the frequency decreases. (For a more detailed explanation, see the encyclopedia) is best understood by the Doppler effect of sound:

The oncoming train whistle is high-pitched, and the departing one is muffled—this is due to the changing position of the sound source relative to the observer. In general, the principle of celestial relativity in the universe is that the light wave is elongated and there is a redshift phenomenon. When a few celestial bodies are close to us, the light wave is shortened, and the phenomenon of "purple shift" appears.

As shown in the figure below, the schematic diagram is made by himself, and I hope the landlord can eliminate his doubts after seeing it. Note: Distant celestial bodies are away from us.

The shift of a line in a celestial spectrum to the red band in a comparison spectrum of a laboratory light source. The definition of redshift z is: z = ( =δ .

where is a certain spectral wavelength of a laboratory light source, which is the same spectral wavelength of a celestial body. z>0, redshifted, wavelength increased; z<0, violet shift, wavelength decrease. In the redshift problem, z is greater than 0, so z is often simply used as the symbol of redshift.

z is a dimensionless scalar quantity, and it is customary to convert z to the corresponding velocity according to the Doppler effect. A red shift indicates that the light source is moving away from the observer.

To put it simply, the original wavelength of electromagnetic waves in the light of celestial bodies becomes longer due to the regression of celestial bodies or the gravitational pull of huge celestial bodies, and the spectrum appears to move towards the red end.

The redshift is the wavelength that becomes longer, and the corresponding blueshift is the wavelength that becomes shorter.

For the cosmic spectral line redshift, it may exist from the point of view of possibility.

The reason for the formation of the spectral line frequency shift in the third is that the distance effect is many.

The Empler effect and the Compton effect are theoretically proposed in this paper.

The other one is the method of forming the main cause. And for trials.

The possibility of the result of the proposed possible influence on the idea of the universe.

Spectrum is the characteristic of a certain element, each element has a specific wavelength of radiant light, and the wavelength is fixed regardless of physical and chemical conditions.

But there are other conditions that can cause changes in the wavelength of the spectrum, namely the redshift or blue shift of the spectrum caused by the movement of the light source, but of course, first we have to identify the elements in the spectrum of the celestial body.

Does it mean "Doppler shift"? There are dividend shifts and blue shifts. Read more books.

1.Due to the Doppler effect, the spectrum of light emitted from stars that have left us shifts towards the red light spectrum.

2.The displacement of a celestial body's spectral spectrum towards the long-wave (red) end. The wavelength of light or other electromagnetic radiation from celestial bodies may be stretched due to motion, gravitational effects, etc.

Because the wavelength of red light is longer than that of blue light, this stretching has the effect of shifting the spectral features of the optical bands towards the red end of the spectrum, and these processes are referred to as redshifts [1].

Vegetation curve redshift 3Redshift in the field of hyperspectral remote sensing. In the spectral curve of vegetation, the red-infrared transmission curve of stressed plants shifts towards shorter wavelengths (Cibula and Carter, 1992) and is called "red-end blueshift" or redshift for shorter.

To put it simply, the inflection point in the 700 nm wavelength range shifts in the direction of the short wave (as shown in the curve on the left). Redshift is generally caused by vegetation stress, which is explained as follows:

The spectral reflection of leaves is most likely to first reflect vegetation stress in the sensitive visible range (535 640 nm and 685 700 nm). When vegetation is stressed and chlorophyll production begins to decline, the lack of chlorophyll generally reduces the uptake of plants in the chlorophyll absorption zone. Such plants have much higher reflections, especially in the red and green light sections.

John R Jensen) As a result, the plant turns yellow or wilts. The increase in the reflectivity of visible light is actually exactly the same as the response of leaf reflectivity when vegetation is subjected to stress. It is only when it is large enough to cause this severe dehydration that the IR reflectance begins to respond (i.e., begins to redshift).

On the right, the spectrum of distant galaxies in the visible light band, compared with the spectrum of the Sun on the left, you can see that the spectral lines are moving in the direction of red, i.e., the wavelength increases (the frequency decreases).

The physical meaning should be explained with physical knowledge

A redshift in the spectral line means that the wavelength of the electromagnetic wave becomes larger and the frequency becomes smaller, so it is biased towards red light.

There are two explanations for the frequency reduction:

1.The Doppler effect is analogous to the fact that two objects are relatively far apart, that is, the expansion of the universe leads to a redshift in astronomical observations.

2.According to the general theory of relativity, light is pulled when it passes over a relatively massive object (like a gravitational field), causing the optical path to bend and lengthen, and the wavelength to become relatively larger, resulting in a red shift.

There is no physical meaning, only a practical meaning, which is what the One said.

Red-shifted, blue-shifted.

In layman's terms, redshift is a phenomenon on the spectrum produced by spectral lines emitted by objects that are far away from us.

A blue shift is a spectral phenomenon created on the spectrum of spectral lines emitted by objects close to us.

Like redshift, violet shift is motion in the opposite direction. Redshifts and violet shifts are like planets and ours forming a catch-up and encountering problem, making wavelengths appear long and short, respectively.

The phenomenon of frequency shift of the observed wavelength of the celestial spectral line to the direction of the long wave.

Light has a certain wavelength, and when the luminous object moves, the wavelength changes (Doppler effect).

When the luminous body is far away, all the light observed will have a wavelength longer than the actual one (that is, the visible light received is close to the red light with the longest wavelength), which is the red shift.

It is also possible that when light is emitted from a strong gravitational field, the received light will also become longer in wavelength and the gravitational force will be redshifted.