1. Morse Code
In order to transmit useful information to distant places as quickly as possible, ancient China built many beacons on the roads from distant frontiers to the capital. In Taiwan, whenever there was a war or other emergency on the border, beacon fires would be set off at one station after another to convey the information to the emperor in the capital. However, the beacon tower was very expensive to build, and it required people to be stationed on watch day and night, and it could not convey the specific content of the message. Therefore, a large amount of information had to be transmitted manually.
In 490 BC, the Greeks defeated the Persian army at Marathon and won the victory in defending their country. In order to let the people in the capital share the good news as quickly as possible, without any means of transportation, the general of the Greek army sent a soldier named Phidipis to run non-stop from the Marathon Plain to Athens, the capital of Greece at that time. . When Feidipi reported the good news of victory to the people of the capital, he finally collapsed and died due to extreme fatigue. In order to commemorate this hero forever, people listed the entire distance he ran (42,195 meters) as an event in the long-distance running competition and named it the marathon. In ancient times, it was so difficult for people to convey information. In ancient times, people tried their best to find the fastest way to transmit information. However, they could only create "clairvoyance" and "sound ears" in mythical novels to express their ideals.
The ideal of "smooth ears" was finally realized by an American painter. He was the inventor of the telegraph, Morse.
One autumn in the early 19th century, on a sailing ship, a group of passengers were gathered around a doctor named Jackson, listening to him talk about the recently invented electromagnet: a horseshoe-shaped magnet wrapped with wires. When an iron block is energized, it will generate an attraction; when the current is cut off, all the iron substances it attracts will fall off. Everyone was attracted by this new thing. Morse happened to be present at the time. While he was curious, he thought deeper and further than others around him. He asked Jackson a question: How fast does electricity flow in a wire (which shows that Morse had no knowledge of electricity)? When he knew that the speed of electric current was so fast that it could pass through thousands of kilometers of wires in an instant, a bold and novel idea appeared in his mind.
A chance encounter on the ship changed Morse's life path. He gave up his beloved painting career and began the arduous research work of inventing the telegraph. More than ten years later, he finally succeeded. Using the principle of one-off and one-off current, he invented the telegraph machine and the code that uses dots to express information - "Morse Code" (selected from the current primary school nature textbook). Telegraph code is one of them), which makes communication more convenient.
Although telegrams can quickly transmit information content, the sender must first convert the information content into symbols and send the symbols to the recipient according to certain operating rules. After the recipient receives this symbol, it is still troublesome to use the code to translate the content it represents. How great it would be if speech signals could be transmitted directly! Human beings will never be satisfied. After the invention of the telegraph, they have created new problems for themselves.
The first person to declare war on this problem and win was Bell, an American teacher who studied deaf languages. Bell knew nothing about electricity when he began working on this problem. However, in the process of studying human vocal cords, he thought: Sound is produced by the vibration of vocal cords. Can this vibration be sent out through changes in the strength of the current? Can the vibration of an object be turned into a changing current, and then the changing current be restored to the vibration of the object to produce sound? This is really a big problem.
In order to realize his ideal, Bell came to Washington, thousands of miles away, and learned electrical knowledge from scratch. After three years of hard work, with the help of mechanical craftsman Watson, he finally made the world's first set of microphones and receivers in 1876. The ideal of transmitting sound through electric current was realized. However, the phone noise at that time was too loud and the transmission distance was too short, so it was still far from practical application.
In 1878, the great inventor Edison made major improvements to the telephone, increasing the call distance to more than 100 kilometers.
In 1915, Bell further solved a series of technical problems caused by long-distance calls to telephones. Finally, in this year, the United States established the first telephone line with a length of more than 6,000 kilometers. of telephone lines.
Nowadays, the telephone has become an indispensable communication tool in people's lives.
In some developed countries, on average every 1 to 2 people have a telephone. Telephones also have more and more functions: some telephones can automatically record the other party's message on tape when the owner is away; some can also transmit handwritten text or graphics in addition to making calls; some can even The callers can see each other through the fluorescent screen in front of the telephone. This is really more magical than the mythical clairvoyance and ears, because this video phone has the dual functions of clairvoyance and ears at the same time.
2. The extremely powerful bronze mirror
One day in 212 BC, the powerful Roman Empire launched an attack on the weak Syracuse. Enemy forces were approaching Syracuse from both sea and land, and the entire country was in danger.
At that time, according to the king's order, the command of defending Syracuse was assumed by Archimedes.
Seeing the Roman fleet getting closer, Archimedes still stood calmly on the castle and looked at the bay in the distance. Suddenly, a thought flashed into his mind: "O powerful sun! I hope your power can help me save the kind people of Syracuse." He decisively issued an order for all women to pick up their bronze mirrors. Gather at the beach.
At this time, the enemy saw many women wearing white robes gathering at the dock of the port, but they could not figure out what trick Archimedes was playing.
As the Roman fleet approached the dock step by step, they suddenly saw bright beams of light coming from the opposite side. These beams of light kept moving, and finally, hundreds of beams of light were concentrated at one point. That spot was so bright and scorching that it fell on the ship's sail and set it on fire.
The fire continued to spread with the sea breeze, and suddenly the entire fleet was plunged into a sea of ??flames. The panicked Roman soldiers jumped into the sea one by one with their bodies covered with fire.
The Syracusan women on the shore were all very happy, holding the mirror in their arms and cheering loudly: "The Romans have been repelled, the Romans have been repelled!"