the air of the gods

Ether is a famous anesthetic. So why are radio broadcasts "on the airwaves", even though they are not designed to put us to sleep? And what about the Greek gods? 

Author: Zvi Atzmon, young Galileo
The ancient Greeks believed that the world was made of four elements - earth, water, air and fire - and that all things on earth were made of different combinations of these four elements. The Greeks also believed that there is a fifth element, which fills the space above the air, and from which the heavenly bodies are built. On this foundation, which they called ether, apply, so they thought, completely different laws from the laws of nature that govern the earth. In everything that is built from the four earthly elements - trees, stones, animals and humans - so they argued, changes occur, and it tends to move in a straight line. For example, an apple falling from the tree to the ground. In contrast, they thought that the heavenly bodies, which are built from the fifth element, do not change and their movement is not straight but circular.

The word "air" in Greek is reminiscent of the English word air, and the fifth, heavenly element is also called by a similar name - ether. The word "ether" was used in Greek mythology to denote "heavenly air", the special air that the gods breathe.

Today we know that the heavenly bodies are governed by laws of nature that are similar to the laws that govern the earth, for example the law of gravity causes an apple to fall from the tree to the ground, and also causes the moon to circle the earth. We also know that the world is not made of four or five elements, but of more than ninety chemical elements. However, the ancient term "ether" remained in use and took on different meanings.

The stuff that fills the universe
When people stopped believing in Greek gods, scientific theories were needed to describe the matter that fills the universe. For example, some thought that a type of substance (ether) was responsible for the earth exerting a gravitational force on the moon; It was also thought that the sun causes the earth to revolve around it thanks to a gravitational force transmitted through the ether. According to this concept, the ether is a kind of special substance that "conducts" the force of gravity between bodies. Some also thought that the ether allows the passage of electromagnetic waves, such as light from the sun to the earth or from the stars to our eyes, but in the experiments no evidence was found for the existence of matter that fills the universe.

Like light, radio waves are also electromagnetic waves (the difference between radio waves and light is the wavelength). They can spread in matter - in air and in empty space. This way we can receive radio waves from the sun, and even from much more distant stars. This way we can also transmit radio transmissions to the communication satellites in space, and receive transmissions back from them. But the idea that electromagnetic waves need matter in order for them to move and spread (just as sound waves need matter, for example air, for them to spread) penetrated so deeply into the mind that radio broadcasts are called "Ether waves" - but this is just an expression.

Sleep on it
In the history of medicine, ether was an important and useful agent for anesthesia. General anesthesia is a condition in which a person loses consciousness, a temporary and transient loss; He stops feeling the various stimuli - he does not see, he does not hear, he does not feel pain and he is not aware at all. The possibility of creating general anesthesia is a necessary condition for performing complex surgeries. Today there are many substances that can be used to induce general anesthesia.

Ether was one of the first substances used in medicine for general anesthesia. The anesthetic is an organic, colorless, very volatile liquid (at normal room temperature it is a liquid, but already at body temperature it is a gas), which the patient inhales into the lungs. Medical use of ether for general anesthesia has been made since 1840. Today it is almost not used in medicine because there are safer and more convenient substances. One of the disadvantages of ether is that it is highly flammable, and this is dangerous. Its use is also sometimes accompanied by side effects such as nausea and vomiting after waking up.

This substance was first created in the 16th century, and it was only in the 18th century that the name "ether" was proposed to it, being a kind of heavenly substance. Today it is indicated by more detailed chemical names, such as diethyl ether. Ethyl is a chain that has two carbon atoms, and ether indicates in chemistry a compound similar to the anesthetic ether - a compound in which carbon chains are connected through an oxygen "bridge". Since a carbon atom is denoted by the English letter C and an oxygen atom by the English letter O, diethyl ether can be described with the formula CCOCC (a short line between the letters indicates a chemical bond). Besides the use of ether as a general anesthetic, it is an important solvent: many substances are dissolved in it in industry and in chemistry laboratories; Of course, you have to work carefully: it is flammable and also... anesthetizing.

So when the radio broadcaster says "I'll meet you on the airwaves" he doesn't mean to put you under general anesthesia, nor does he mean a meeting with ancient Greek gods...

The article appeared in the May issue of Young Galileo – Monthly for curious children

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