When in space, the astronauts will be wearing special protective suits, with tight-fitting helmets, oxygen and special tools, communication devices with microphones placed near the mouth. But outside that suit is still a vacuum. So why can they still hear, call and communicate with each other?
In fact, all of our communication devices use radio waves to transmit. And radio waves work like light, they don’t need air to propagate, and the longer they are in a vacuum, the more effective they are. All electromagnetic waves, including visible light, do not need a medium to propagate and therefore it travels the fastest in a vacuum – 300,000 km/s. This is how the sun’s electromagnetic radiation propagates to our Earth – traveling through 150 million kilometers of high vacuum space.
To better understand, we need to learn about the mechanism of phone calls.
Telephone is a great invention of man, appeared in the 18th century and was officially used as a communication device after the middle of the 19th century. The first person to apply for a patent for the invention of the telephone was the English inventor Alexander Graham Bell, who applied for a patent for the telephone in March 1876, so he is known as the father of the telephone.
However, on June 15, 2002, the United States Congress passed Resolution 269 identifying Antonio Meucci as the inventor of the telephone, because he first showed his invention to the public in 2005. 1860 and published in an Italian newspaper about his invention.
In this way, we implicitly acknowledge that there are two fathers of the phone, and who really made the first human phone, we still have no conclusion. So we will put this issue aside to talk about how the phone works.
After the invention of the telephone, from the simplest point-to-point short distance call, it gradually evolved to long distance calls, multi-person calling, video calling, etc., from manual switching to dial-up phones, program-controlled telephones, dual-tone multi-frequency telephones, etc., more and more modern new technology, Internet telephony, digital mobile phones, etc., more and more calling methods follow accordingly. it’s getting more and more convenient.
But no matter how it works or in what form, the essence of the phone remains the same, that is, talking here, answering there and communicating with each other via voice. The basic principle is that people emit sound waves through their mouth, transmit the sound waves to the microphone, convert the sound waves into sound vibrations through pickup devices in the microphone, and then convert the pitch of the knife. into a variable current.
Electric current is transmitted to the receiver’s phone via wires or radio waves, and the receiver in the phone converts the current into acoustic vibrations through a set of processes opposite to that of the transmitter, after That converts into voice sound waves, which are transmitted to people through the air or ears. In this way, both parties in the phone call form a communication channel.
By understanding the basic operating principles of the above-mentioned phones, we should clearly see that in addition to transmitting electrical waves, phones also need a basic and indispensable transmission tool – sound waves, no radio waves. sound, the phone cannot transmit and receive voice.
Therefore, astronauts in outer space, wearing special protective clothing, can completely listen and make normal phone calls. However, if you take off that suit, in a vacuum environment, sound will not be able to propagate. Why is that?
Sound waves are mechanical waves. The difference between mechanical waves and electromagnetic waves is that electromagnetic waves can travel without a transmission medium, and sound waves must have a transmission medium. The simplest and most common medium is air, and sound waves can only travel through vibrations of air and other media. Sound waves travel at about 340 m/s in air and faster in steel at about 5,200 m/s.
And of course in a vacuum, there’s no transmission medium, so even if you weren’t suffocated to death in this environment, sound would have no way of reaching the microphone. If the person answering the phone is also in a vacuum, because there is no sound wave vibration, sound cannot travel through the external auditory tube to the eardrum, and the microphone sound cannot be heard.
So, in a vacuum state, without special protective suits, oxygen, people not only can’t survive, but also can’t make sounds, can’t make or receive calls.