Questions about the Doppler effect and the theory of relativity

Electromagnetic waves have a Puller effect, and the redshift and blueshift affect the wavelength and frequency, but do not affect the speed of the wave, and the speed of the electromagnetic wave is the speed of light.

The velocity of electromagnetic waves does not change in relative motion, which is in line with the theory of relativity. The blue-red shift of electromagnetic waves in the gravitational field conforms to the general theory of relativity.

Shrinkage is related to the speed of relative motion, and shrinkage is directional, and only in the direction of your relative motion does shrinkage occur.

If you haven't understood the analogy: imagine a ruler that is trembling (fluctuating) and flying towards you at less than the speed of light, the ruler seems to be shorter, and the ruler seems to tremble more violently when it flies towards you, and it trembles more peacefully when it flies away from you, but it is still shorter. If the ruler flies at the speed of light (provided that the ruler does not have mass, otherwise it cannot reach the speed of light), then its length is too short to be there, but you can still observe the trembling of the ruler, which is violent when it flies towards you and peaceful when it is far away from you.

In a word, there are many sentences: the Puller effect affects wavelength and frequency; Whereas, the behavior of electromagnetic waves is in accordance with the theory of relativity. There is no contradiction between the two.

Sound waves have a Doppler effect: the whistle of a train is more harsh than usual when the train approaches an observer. You can hear the change in the screeching sound as the train passes by. The same goes for the sirens of police cars and the engines of racing cars.

Electromagnetic waves also have the Doppler effect, but the causes are different from mechanical waves.

Please first understand the difference between the classical Doppler effect and the relativistic Doppler effect, the latter includes the former.

The speed of sound is not the same as the speed of light, the speed of sound without discussing the relativistic effect is the classical Doppler effect, while the speed of light without discussing the relativistic effect is without the Doppler effect.

The Doppler effect of the speed of sound is different from the relativistic effect of the speed of light and the relativistic effect of the light. Because the speed of light is always constant with respect to any moving frame of reference, the speed of sound has no such property.

The relativistic effect mentioned above refers to the effect produced when the relative motion is close to the speed of light, which is exactly what the landlord calls the shrinkage effect.

I don't bother to talk about the specifics...

First of all, the answer is yes, and redshift is such a phenomenon.

Also, does the shrinkage affect this?!?

And then again: sound waves are not electromagnetic waves.

Suppose the light source is at the origin of the inertial frame s o and the observer is in the inertial frame s'The origin of O'，s'The origin of the system'、x'shaft, y'axis, z'The axes coincide with the origin of the S system, the O, X, Y, and Z axes, respectively. If s'The system is relative to the S system with velocityvIf you move in the positive direction along the x-axis, then the s system is a stationary system, s'The system is a system of motion, and the velocity of the light emitted by the light source relative to the positive direction of the s system along the x-axis is the absolute velocityc，s'The velocity of the system relative to the S systemvis implicated in the velocity, zen and light emitted by the light source with respect to s'The velocity of the system in the positive direction along the x-axis is the relative velocityc', according to the law of velocity vector synthesis, absolute velocitycEqual to the speed of implicationvwith relative velocityc'The sum, iecvccvc'The size is c=c、v=v、c'=c', the ridge key assumes that the vector unit along the positive direction of the x-axis isi, thenc=civ=vic'=c'i, thus having ci=vi+c'i, i.e., c=v+c'。According to the facts of the Mai Sakura Attack Cho Kelson Morey experiment, the light is relative to the s where the observer is located'The velocity of the system is always c, so c'=c, v=0, the relativistic "Doppler effect equation" is in fact = 1+(0 c)cos']1-0 c), this is the truth of the "Doppler effect equation" of relativity, and it can be seen that the so-called "Doppler effect equation" of relativity theory is completely a pseudoscientific lie fabricated by Einstein.

There are three formulas for calculating the Doppler effect:

1. Longitudinal Doppler effect (i.e., the velocity of the wave source and the connection between the wave source and the receiver are collinear): f'=f[(c+v) (c-v)] 1 2), where v is the relative velocity of the wave source and receiver. When the wave source approaches the observer, v is normalized, which is called a "violet" or "blueshift".

Otherwise, v is negative, which is called "redshift".

2. Transverse Doppler effect (i.e., the velocity of the wave source is perpendicular to the connection between the wave source and the receiver): f'=f(1- 2) (1 2), where =v c.

3. Universal Doppler effect (general situation of Doppler effect): f'=f[(1- 2) (1 2)] 1- cos), where =v c, is the connection between the receiver and the wave source to the direction of velocity.

The Doppler effect was proposed by the Austrian physicist and mathematician Christian Johann Doppler in 1842. The main content is that due to the relative motion between the wave source and the observer, the observer feels the phenomenon of a change in frequency.

This effect is also caused by fluctuating light, also known as the Doppler-Fizeau effect. In 1848, the French physicist Fizeau independently explained the wavelength shift from the star, pointing out the method of measuring the relative velocity of the star by this effect. Light waves differ from sound waves in that the change in the frequency of the light wave makes a person feel like a change in color.

If the star moves away from us, the spectral lines of light move in the direction of the red light, which is called a redshift. If the star moves towards us, the spectral lines of light move in the direction of violet, which is called a blue shift.

Clock slowdowns directly lead to the relativistic Doppler effect (Doppler shift). When there is a relative motion between the light source and the observer, the frequency of the light wave measured by the observer will be different from the light frequency when the light source is at rest, and this difference is called the Doppler shift. The classical theory also predicts the Doppler shift, but the prediction of special relativity is different from the prediction of the classical theory.

The difference between the two types of prophecies is caused by the fact that the speed of a moving clock is different from that of a stationary clock, which is caused by the clock slowing effect.

The frequency and direction of propagation of light rays are transformed under the Lorentz transform according to the following formula:

=(1－v·cosθ/c)(1－v2/c2)1/2 cosθ'=(cosθ－v/c)(1－v·cosθ/c)

Sum in the formula'respectively in the K line and K'The measured frequency of the light wave in the system, and'The direction of propagation of the rays is the same as the x-axis and x, respectively'The angle between the positive directions of the shaft. When =90° (i.e., perpendicular to the direction of the ray).'=v/(1－v2/c2)1/2

This is known as the transverse Doppler effect (which is not present in Newton's classical physics). The transverse (or second-order) Doppler effects actually come from the time dilation effect, and they have been directly confirmed by many experiments.

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In-depth analysis of the "Doppler effect" is applied to the medical detection of blood vessels.

To put it simply, when the signal source moves relative to the observation point, the observed signal frequency will change with the different speed and angle of the signal source.

The broadening or reduction (frequency change) of this frequency is called a Doppler frequency.

Ultrasound measurement of blood flow rate makes use of the Doppler effect.

There are also examples in life, when the train passes, the closer it is, the thicker the sound of the whistle, and the farther it goes, the sharper the sound, which is due to the movement of the train, which causes the frequency of the whistle sound that we observe to change.

1。In order to explain the meaning behind the Doppler phenomenon, it seems that it is not necessary to think in terms of spherical waves, without pulling in the directionality of space, and it is better to imagine with a simplest plane wave. Velocity is equal to wavelength times frequency, which seems to be unconditionally correct, this is a definition, but it should be noted that velocity is a vector quantity, and there is nothing wrong with this definition in each component.

2。There are two Doppler explanations, one that can be deduced using the relativity of time and space in special relativity (the Lorentz transform formula), and the other that can be deduced using the equations of motion of Newtonian mechanics. The meaning behind this is the relativity of physical quantities and the interconnectedness of time and space.

A and B are relatively stationary, A sees the wavelength emitted by B (such as a sound wave) as one value, and when A and B are in relative motion, the wavelength seen (the distance between peaks and peaks) is another value.

It is not paradoxical to assume that the wavelength of the light wave is in an inertial frame"At the same time"The difference between the coordinate values of the two endpoints of the resulting periodic wave. Due to"At the same time", the wavelengths measured in different inertial frames are also different. The theory of relativity, which proves that a ruler moving in the direction of the length of a ruler is shorter than a ruler at rest, can also be applied to light waves, and can also explain the Doppler effect of light from the perspective of special relativity.

According to the principle of special relativity, inertial frames are completely equivalent, therefore, in the same inertial frame, there is a unified time, which is called simultaneity, and the theory of relativity proves that in different inertial frames, there is no unified simultaneity, that is, two events (space-time points) are simultaneous in one inertial frame, and they may be different in another inertial frame, which is the relativity of simultaneity, in the inertial frame, the time course of the same physical process is exactly the same, if the same physical process is used to measure time, Uniform time can be obtained throughout the inertial frame.

The frequency and wavelength of light waves can change at the same time, but the speed does not change, which is reflected in the change in the color of light.