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Most of the extraterrestrial space detection videos that people watch are basically silent, and there are also BGM added later.

This is related to the fact that the competent authority does not play the original sound, and it is also related to the fact that there is really no sound in space.

Sound is a wave propagating through a medium, but some waves are large and some waves are small.

The greater the density of the medium and the closer the distance between molecules, the stronger the ability to transmit sound, because the essence of sound is transmitted by the collision of the molecules of the medium.

Space is not an absolute vacuum, but its medium density is very small, and the distance between molecules is so large that it can't touch one in a long time, so the ability to transmit sound is very, very weak.

The space detection equipment is naturally sound in the process of operation. The collision of various pipelines and components will produce sound. Most people are not interested in this sound sense. Let alone the general sound collection device may not be installed with space detection. equipment.

Because the payload of each rocket launch is "careful" and too expensive. It is a waste of payload to install such "useless" equipment. Isn't it good to install other scientific research equipment?

Such as electromagnetic signal detection equipment.

This thing can receive electromagnetic waves on the planet. Scientists can convert these electromagnetic waves into sounds that human ears can hear. Then people can listen to sounds from space.

Not to mention, the sounds of the various planets in the solar system sound... quite unique.

The "hum" of the sun.

The "howling" of Mercury.

The "bells" of Venus.

The "wind sound" of the earth.

Martian...

Horror, horror, wailing, majestic, chanting, death knell, etc., a variety of sound effects can even make people feel natural fear, hair standing upright, and finally deepen their deep space phobia.

Fortunately, those sounds are inaudible to human ears and require conversion of various devices. Humans will not suffer that kind of sin every day.

Of course, this thing is "human translation", using different methods to "translate", the sound obtained is completely different, so just listen to it.

When it comes to a planet with an atmosphere, the detection direction is different.

Because they have air above them, people can hear sounds in the same way as the earth.

As the two neighbors of the earth, Venus and Mars, humans have studied them "the most thorough", including the sounds in their atmosphere.

On Venus, all voices will become low.

If the soprano on the earth arrives on Venus, it will become lower than the bass, so the wonderful songs on the earth are probably no longer beautiful on Venus, just like the record player is almost out of power.

If the tiger on the earth arrives on Venus, the tiger's roar will be thicker and deeper, but it will make people feel like a heavy sound made by an alternative little animal. It is not only low, but also weak.

Probably it's a tiger that doesn't show off, or a kitty cat that looks like a tiger, with a pink bow.

But no matter how low the voice is, it can spread very fast and very far on Venus.

Why is it so?

As mentioned earlier, the propagation of sound is related to the type, density and temperature of the gas.

In a gas with larger molecules, higher density, and lower temperature, the faster the sound propagation speed, but the lower the vibration frequency of the sound, that is, the lower the tone.

It is easy to understand that dense matter spreads sound faster, just like solids such as steel on the earth transmit sound faster than liquids such as water, and water transmits sound faster than air.

People and people cannot be generalized, and of course planets and planets cannot be generalized.

The atmosphere of Venus is as dense as a liquid. The density is 100 times that of the earth's atmosphere, and the pressure is much greater than that on the earth.

To stir up fluctuations in the dense atmosphere in such an environment, more energy is required.

Therefore, if the same sound vibration reaches Venus, the vibration amplitude of the Venusian gas it arouses is smaller, so the tone becomes thicker and the sound becomes weaker.

The sound on Mars will be the opposite of that on Venus. The sound will become sharper on Mars, but the speed of sound propagation will be much slower and the propagation distance will be much shorter.

That's because the sound transmission on the ground is equivalent to the atmosphere of 30,000 meters above the earth, and the air is thin.

More than a decade ago, Meriken’s space agency launched the Phoenix Mars rover, with the purpose of detecting whether there is life under the soil or ice caps in the polar regions of Mars.

During the Mars landing, scientists added a microphone by the way.

The Phoenix landing was lucky, and the whole process was captured by Europa’s Mars Express orbital probe.

Through the microphone on the Phoenix, scientists can hear the sound of the Phoenix landing.

When it descended with the parachute, it turned out to be the sound of fine raindrops, and then the sound of raindrops mixed with whistle, the whistle became more and more sharp.

When the Phoenix freed from the parachute and fell freely, the whistle sound became unusually harsh. Later, when the recoil engine was turned on, the sound similar to that of a robot could be heard.

For the increasingly sharp whistle, the scientists' interpretation is this: It should be the Doppler effect of Europa's Mars Express flying over the Phoenix.

Just like when a train comes from a distance, we will feel the whistle sound getting sharper and sharper. After the train passes, the whistle sound becomes lower and deeper.

The sound of the Phoenix traveling through the Martian air is indeed much sharper than the sound on Earth, but it is getting sharper and sharper, and it is caused by the Doppler effect.

As for the fine raindrops heard, scientists initially guessed that it was caused by the impact of dust or ions on the rover over Mars.

Today, the Trailblazer, which uses the "ton" as the basic quality unit, is equipped with a more sophisticated sound recording device, allowing you to hear various sounds more clearly.

The sound of the "Sky Trailblazer" unmanned detection helicopter taking off is very loud, but it is transmitted through the thin air to the sound recording device, and then converted into a signal and transmitted to the earth, and then converted into a sound, which is heard by millions of humans. It's a sharp "hum", and it's not loud.

Fortunately, when the landing device first entered the atmosphere, they also heard a faint "raindrop" sound, so the volume was increased, and the sound can now be heard.

However, as the helicopter flew higher and higher, people could not hear the sound after only a few tens of meters.

Where the air is thin, the sound transmission distance is so urinary.

The rest is a few hours of the helicopter on the way.

Although Tang Chao knew who the four aliens were, the other earthlings didn't know, so he could only pretend not to know, and for this he also formulated a complete set of contact methods.

According to the helicopter's single flight time, it is possible to fly directly from the landing site to the alien's location, but everyone does not allow him to play that way. It must be landed and trimmed when it is close to the alien's location, and then fly after the flight power is charged. past.

If it flies directly, the helicopter will definitely enter a "rigid" time of up to 30 minutes. If there is any interstellar diplomatic conflict, it will be impossible to run.

Therefore, it is necessary to ensure that the helicopter has relatively sufficient power to support the flight and fly away immediately if there is a problem.

The alien spacecraft crashed. After long-term satellite monitoring, people found that they had no redundant flying equipment, and there was a high probability that they would not be able to cause damage to the helicopter, nor could it keep up with the helicopter's flying speed.

This is a rare opportunity to contact aliens, even if it is not led by itself, any country does not want to waste this opportunity at will, especially those countries without space capabilities.

Yes, Tang Chao was connected to the UN General Assembly this time, and his head also appeared at the joint meeting, and the largest screen on the scene was the live broadcast.

If there is an accident in this contact, the next contact will be nothing for most countries.

After all, other countries will not live broadcast globally like the leader company. Although they have signed an information sharing agreement, they do not even live broadcast. How much credible is the shared information?

This is contact with aliens.