Fun knowledge worth knowing

Ladder to heaven: Ji Mang Pyramid
Three giant pyramids stand on the desert plateau near Cairo. The most famous of these is the Great Pyramid, the only one of the seven wonders of the world that remains intact.

Extraordinary feats often provoke extraordinary explanations, such as space aliens! Super advanced civilization lost! But the facts are more interesting. During the Fourth Dynasty (2575-2465 BC) 4,500 years ago, three Egyptian pharaohs supervised thousands of workers and built landmarks in Giza for 70 years. Recent archaeological discoveries, including diaries of inspectors involved in pyramid construction, have more to explain how the pyramids were built and who built them, but there are still many puzzles.

Giza Pyramids
The Pyramids of Giza are the brainchild of the three generations of Egyptian kings. Hufu is the oldest of the three and is the father of Hafra. Hafra is the father of Menkaura. Each pyramid is considered to be the last resting place for the king who ordered it.

Gate Kaura Pyramid
Built in 2510 BC

Size: 2.9 acres

Height: 218 feet

During the building it was called “Mencaura is sacred”. The Menkaura Pyramid is the smallest of the three pyramids. It was originally 66.5 meters high and is now only 62 meters high. The hole was caused by someone destroying it. There are three small pyramids on the side, which is his wife.

Why build the pyramids?

The Pyramids of Giza are the tombs of the royal family. Scholars say that the shape was built to help the king board the sun god and ensure eternal life. The sloping side of the pyramid may be inspired by the slanted sunlight that hits the Earth.

The purpose of the construction is to let the pyramid reflect the light of the sun and let the soul of the king reach the temple of the sun god with the light.

Inspector Mercer’s Diary
In 2013, the Egyptian antiquities scholar Pierre Tale of the University of Sobe in Paris and his team found pieces of papyrus between the stones of a building in the Red Sea port during the reign of Khufu. This is part of a daily log of an inspector named Mercer who is responsible for supervising cargo ship personnel transporting limestone from Tula to the Giza Plateau. Mercer called the Great Pyramid “the horizon of Khufu” and called the pyramid site “Hof’s swimming pool.”

Khafre pyramid

Built in 2570 BC

Area: 11.5 acres

Height: 471 feet

It was called “great Hafra” during the construction period. The fourth pharaoh of the fourth dynasty of Egypt, Havra, inherited the throne of Khufu and established the second largest pyramid in the world, the Hafra pyramid in Giza. The Hafra pyramid was built steeper than the Huf pyramid, and it is at the highest point of Giza, so it looks higher than the Khufu pyramid. There is a temple in front of the Hafra Museum, and the long causeway in front of the temple leads to the temple and the Sphinx in another valley.

Khufu Pyramid

Built in 2580-2560 BC

Area: 13.1 acres

Original height: 481 feet

It is the pyramid of Pharaoh Khufu, the fourth dynasty of ancient Egypt. It is mainly used as its mausoleum and the largest, highest and best Egyptian pyramid in the world. It was called “the horizon of Khufu” during the construction period. The base is almost completely square and the outer stone fits precisely to the outer casing. It is also the largest single ancient building in the world. It is said that the Khufu Pyramid was built by 100,000 people in 20 years.

History of pyramid growth
In about 500 years, ancient Egyptian tombstones have evolved from simple mounds to timeless architectural wonders.

Mounds before 4600-3000 BC before the reign of the dynasty

The ancient Egyptians believed that the creation originated from the original mound. This may prompt them to bury the dead in a pile of mud, I believe this may help the rebirth of the next life.

Early dynasty 3,000-2686 stone chamber graves

The mound slowly develops into a huge rectangular mud brick monument called the tomb, which means “long bench” in Arabic. The “stone chamber grave” became the last resting place of the Egyptian royal family, and its body was placed in the basement below the building. Later stone chamber graves were also built of stone.

The third dynasty, the ladder pyramid from 2686 to 2613 BC

The builder began to stack a stone chamber grave on top of the other, with the stone tomb above it smaller than the one below it. Pharaoh José built a six-level trapezoidal pyramid in Segara, 10 miles south of Giza.

Early fourth dynasty, 2613 – 2494 BC

Curved pyramid

The father of Khufu, the first king of the fourth dynasty, Segara, built the so-called curved pyramid at Dahshur, 14 miles south of Giza. This is the first large project to create a monument with a sloping triangle edge. But the ground is softer than expected, so in order to avoid the collapse of the pyramid, the laborer reduced the slope of the top and created the curved appearance of the pyramid.

Red pyramid

Segara tried again in Dahshur, this time creating the first real pyramid with red limestone on the outside.

How did the stone that built the pyramid come?
The stones used to build the pyramids were sourced from the Gussa quarry and the Nile. Workers are transported to the construction site in various ways.

Through the sled

Stones that are cut into pieces may be placed on a sled and pulled by a person or cow. Water or other liquids falling on the ground will reduce the forward friction of the ski.

Researchers have simulated this practice many times. This method is feasible with the right technology and sufficient power. In 1991, a famous pyramid building simulation experiment was carried out, using ancient Egyptian tools and methods to build two sides of an 18-foot pyramid in 21 days. During the construction period, more than a dozen men tied a rope to a sled with 2 tons of heavy stones. “We moved these stones effortlessly,” said Richard Redding, a research scientist at the University of Michigan’s Kelsey Archaeological Museum.

The floodplain of the Nile extends to the Giza Plateau, providing conditions for workers to transport quarries by boat.


White limestone once covered the pyramids of Khufu and Khafre. (Some still remain on top of the Hafra pyramid) “When the sun shines on this white limestone, the entire valley can see the reflection.” Redding said. White limestone comes from the Tula quarry on the east bank of the Nile, 8 miles away. The granite beams in the interior are mined in Aswan, hundreds of miles south of the Nile.

The stones of the Tula and Aswan quarry are transported by cargo ships to the Giza Plateau. Before the completion of the modern dam, the Nile River will be flooded from August to October every year, and the water will wrap around the pyramid building.

In the late 1980s, sand profile analysis and 72 sediment core samples collected by an Anglo-American company showed that Egyptians excavated canals and ports on flood plains to help cargo ships pass. “They cut off the surface of the plateau to create these deep-sea ports, some of which are deep enough to keep flooding during the off-season, making it easier for ships to transport goods,” said Glenn Dash, a surveyor in the Giza area.

Need a ladder?

How did the Egyptians stack so many tons of large stones to build hundreds of feet of pyramids? Scientists and historians have come up with many theories, from well-designed slopes to pulleys, pulling the blocks on the sloping sides and manipulating the fulcrums in place. But the exact method is still unknown.

Most researchers believe that this type of building involves a kind of slope, which may be composed of gypsum, clay and limestone fragments, especially since the slope remains are still on the plateau. But there is little agreement on how to use ramps in pyramid buildings.

Straight slopes must be very long to transport the blocks far beyond the quarry. This is a feat in itself. This type of slope also does not solve the problem of moving stones to specific points on the pyramid.

The design to change the angle or surround is the most recognized. The ramp may be built from the ground and surround the pyramid. Workers will pull the sled with stones onto the slope for placement.

After completing the pyramid, the gravel on the slope was dumped back to the Giza quarry.

The builder is a worker, not a slave
The Greek historian Herodotus grew about 2000 years after the completion of the Giza pyramid, and he wrote that the slaves built the pyramid. But recent research offers different possibilities.

Conquering labor

The hieroglyphic inscriptions and the information on the monument indicate that masons, surveyors and other skilled workers continue to work in Giza. Reading said that the clumsy work of heavy pulling stones is probably not carried out by slaves, but by young people from rural areas of the region. Because they may not have much choice.

Ancient Egypt is more or less a feudal system, and almost everyone should provide services to citizens of higher social class, including serving the pharaoh. Donald Redford, a professor of classic and ancient Mediterranean studies at Penn State University, said that during the rainy season, when farmland was flooded, thousands of people were recruited into the pyramid project.

City and cemetery

Around the Pyramids of Giza is the vacancy of workers’ settlements and cemeteries. The researchers said that the graffiti wall, a few steps away from the pyramid, showed the occupation of the Fourth Dynasty, when Havra and Menkaura ruled. The discovery of the bones of the slaughtered animals found that the workers are full. “They get better food than they get in the village.” Redding said that he did an animal bone analysis in the area and found that the nearby cemetery was also a worker’s cemetery. This injury was well taken care of and there were no other signs of abuse. “They are very good to the workers and care about them,” Redford added.

Are those unskilled workers dissatisfied? Some researchers say maybe not. Staying in a bustling place with tens of thousands of people can be exciting for young people from the countryside. Some people say that workers may feel that through their work, they are improving their future. “By helping Pharaoh to survive better in the afterlife, and to ensure that he can stand by the gods forever and pray for himself… Your actions are in your own interest,” Redding said.

The end of an era
The climax of the Egyptian pyramid building ended around 2510 BC, and the Menkaura pyramid was completed. This is a monument that is more “mini” than the Pyramid of Khufu and the Khafre pyramid. “They really can’t concentrate on human or financial resources to do it again,” Dash said. “That’s why the pyramid has become smaller and simpler since then.”

The pyramids of Cairo overlook the map, they are the only preserved buildings in the seven wonders of the world.

The cloud is made up of countless drops of water that are too small to be seen with the naked eye. The atmosphere is actually filled with these water droplets, which scientists call water vapor. As the water vapor rises, they will liquefy into small droplets or condense into small ice products, and adhere to things such as dust, ice, sea salt, and even pollutants, thus mixing and floating in the air. Visible polymer cloud.

The cloud presents a variety of shapes. It is divided into many types depending on the height and shape. The Chronicles of the Clouds, the American Meteorological Society, lists three cloud families of three families, the most bizarre of which may be the tallest and thinest at night, at 250,000 feet or more. The clouds are only visible at dusk.

Cloud and climate
In the model, the biggest uncertainty about how much climate change is due to people not fully understanding the impact of the cloud. Will they slow or accelerate warming?

Clouds cover 70% of the Earth’s surface at all times, so they play an important role in climate formation. When the warm rays of the sun illuminate the Earth, the clouds reflect some of the energy back into space, and they capture some of the energy in the air between them and the Earth. So the cloud both cools our world and makes our world warm. In the model, the greatest uncertainty about how much the climate will change comes from an incomplete understanding of the effects of the cloud. Will they slow or accelerate global warming?

Most models predict that changing cloud patterns will exacerbate global warming. There is a model worthy of attention: as the tropical arid regions expand, mid-latitude storms move toward the poles. In 2016, a study published in Nature examined the clouds over the past few decades and found that the clouds did move toward the poles as predicted.

Supercell storm
The supercell is a super large cumulonimbus cloud with a rotating updraft, a single powerful circulation system characterized by an asymmetrical structure of the storm. In the cloud, there is a flow of air that is twisted upwards from the low angle, flowing in the right front of the storm, rotating in a counterclockwise direction at a high altitude, flowing to the front to become a cloud anvil, and finally disappearing into the strong wind of the ambient airflow. Another dry cold airflow enters the cloud from the rear of the thunderstorm in the middle, leaving the storm from the lower rear left. When it enters the cloud, liquid water in the cloud evaporates in it, causing a rapid cooling effect, causing the air to sink strongly, and its sinking speed is proportional to the temperature difference between the cooling air and the surrounding uncooled air. The faster the air drops, the stronger the airflow from the lower layers of the storm. They usually bring a lot of hail, heavy rains, strong winds, and downbursts. Tornadoes can be derived from cyclones in some types of supercells, although this is the case with less than 40% probability. Supercell storms are the most violent and powerful storms you can imagine. They are also the most devastating storm system in many cases, and they are huge in size, with a range of up to 32 kilometers above the ground.

Fortunately, supercells are rare, and storm observers can easily spot classic supercells and issue warnings. It is important to avoid the most dangerous areas of it: downdrafts, too much unsupported rain can cause air to fall back; updrafts, rising air supplies the rotating core of the storm. The downdraft will cause heavy rain and hail, and the updraft will cause a tornado.

1. Cloud anvil

A stormy anvil top that extends upwards.

2. Rotate

Supercells have a rotating updraft, which is caused by rising warm air, which allows them to form strong winds, large hail and tornadoes. Unlike supercells that can last for hours, normal storms are short-lived because they don’t rotate.

3. Flanking line

Cumulus usually extends from the most active area of ​​the supercell.

4. Flying clouds

A low, uneven cloud that is often associated with the cold flow of thunderstorms.

5. No rain base

Under the updraft of thunderstorms, there may be dark clouds that usually do not rain.

6. Overshoot top

The strong updraft forms a dome-shaped projection.

7. Cloud anvil

Where the cumulonimbus is flat, its top stretches to the stratosphere a few miles from Earth.

8. Cyclone

Doppler radar can detect this rotating area spanning several miles.

9. Milky cloud

The so-called milky cloud is formed when the cold air sinks under the thunderstorm anvil.

10. Tornado

A rapidly rotating air column that touches the ground.

11. Wall cloud

Tornadoes are sometimes formed in this rapidly falling cumulonimbus cloud.

12. Beach Cloud

A low-level cloud, usually wedge-shaped, that often occurs before the storm. It is a cloud layer formed on the beach due to special local environmental factors. Its appearance is a long cloud, very rare.

Pigeons are often referred to as “the mouse of the sky”. Why is there such a bad saying in modern society? In fact, this is a social chaos, the seller will make the mouse a “pigeon” to deceive consumers. Still, these birds do have some impressive places.

The pigeons appear in a quirky way, with about 350 species of pigeons recorded, all belonging to the pigeon family, including the white pigeon. Here are some of the most popular features of these raised birds.

Eat: Many pigeons are raised as food sources in the United States and elsewhere.

Special skills: Some pigeons are selected for their abilities, such as the pigeons, which have an amazing ability to find a home. There are also the ability to fly in the air and fly at high altitudes, which can be flipped back in flight – perfect for flying games and performances.

Show: Some pigeons are raised for _, good-looking appearance, including colorful pigeons, which have nice looking bags and markings; ball-chest pigeons bulging their sacs, which seem to be bulging; The pleated and owl pigeons have rich frilly feathers, and the strange shackles and chest hairs make them look like owls; Asian feather pigeons have a fancy feather growth pattern.

How to fly home?
As we all know, these birds are good at finding the way home. This is a familiar skill that is just right. But how they do this still confuses the experts.

Some scientists believe that pigeons use the Earth’s magnetic field for navigation. In 2012, a research team reported that certain brain cells of the inner ear were activated when the pigeons were exposed to a magnetic field. Scientists speculate that these cells can send direction signals, the strength and polarity of the Earth’s magnetic field, and provide built-in GPS for pigeons.

Due to the sensitive hearing and extraordinary memory of the pigeons, some experts suspect that these pilots actually created sound maps to help them navigate with specific audio markers as landmarks. Other studies have shown that they use the sun, certain environmental cues, and even their sense of smell to find directions. Yet another research team claims that birds can actually remember the road and travel along the road. Maybe one day scientists will answer this question.

Interesting thing
The sac: The pigeon is one of only three species of birds with a sac, which is an enlarged extension of the esophagus that secretes nutrient-rich secretions for their pups.

喙: When most other birds drink, they will tilt their heads back and swallow them. The pigeons suck like their sippy straws.

Wings: The dove’s wing muscles account for about 60% of its total weight, which is larger than most other birds, making them strong pilots. They can fly about 500 miles a day at a speed of up to 50 miles.

Feather: When attacked by a predator, the pigeons easily fall off their feathers and escape. This phenomenon is called fear hair removal.

How smart is the pigeon?
Pigeon guided missile

The incredible intelligence of pigeons has always been obsessed by many scientists. In the 1950s, psychologist B. F. Skinner believed that the pigeons could help the Allies defeat Hitler. He teaches pigeons to play table tennis and also trains pigeon-guided missiles. At the time, he demonstrated how the pigeons guided the missiles to bombard a ship model. In the demonstration, the pigeon uses the mouth to smash the target on the screen, so that the missile can accurately bombard the model. Even in the case of a quick drop and an explosion, his pigeons can accurately hit the target. However, because the authorities were skeptical about the reliability and accuracy of the pigeon pilots, the idea was dispelled.

Pigeon recognition letter

Nonetheless, these birds are still one of the few species that pass the “mirror test”, and the “mirror test” evaluates the ability of pigeons to recognize their own reflections, indicating that they have a self-concept. Only about six other animals have this ability. The pigeons also defeated the baby and the toddler in recognizing the letters and understanding of the alphabet. They can even distinguish between different faces and understand certain facial expressions.

Pigeon diagnosis of tumor

Inspired by pigeon-guided missiles, in 2015, scientists began training pigeons to find cancer in medical images. They conducted a series of pathological sections and medical image identification training for the pigeons. At the beginning, the pigeons judged that the correct rate of the slice was only 50%, and after 15 days of training, the correct rate of the pigeons was raised to about 85%.

Why train pigeons to do these things? In traditional pathological diagnosis, trained pathologists directly observe the morphology of tissue cells through a microscope and use various indications to determine what is wrong with the lesion. Experienced pathologists are the only reliable authority in the field, and relying on them to conduct manual evaluations on these ones can be time consuming and costly. Therefore, the researchers hope to find some subjects that can replace the pathologist’s technical improvement research, so they selected the pigeons.

Historical journey
The closest to the now extinct Dodo is the pigeons, which are said to have originated in the Mediterranean, India and the Middle East. They now exist in all places except the Sahara Desert, Antarctica and the Arctic Highlands. Our history with them goes back farther than you think.

About 10,000 years ago: The first clue of human interaction with pigeons dates back to the Pleistocene era. Although the evidence is insufficient, archaeologists believe that our ancestors raised them for food.

About 5,000 years ago: The first evidence of pigeon domestication appeared in ancient Mesopotamian cuneiform tablets and Egyptian hieroglyphics. The first image of the pigeons discovered by archaeologists came from Mesopotamia in 3000 BC.

About 4,500 years ago: Pigeons with special responsibilities had a record: as a food, messenger and sports target, it began to appear in ancient Mesopotamia. Even their feces are used as a component of fertilizers and gunpowder.

In the 19th century, these birds used by companies such as Reuters in Germany were more reliable than telegraphs and faster than any vehicle at the time, used to disseminate information about breaking news and the stock market. In 1855, Charles Darwin began researching and raising pigeons and published his book, The Origin of Species.

The 20th century: In the two world wars, pigeons will pass information from the front to the headquarters. Some of them even become war heroes by transmitting key messages that affect the outcome of the battle. In 1940, pigeons carrying cameras were deployed in many countries to capture ground images.

21st Century: Today, we mainly use pigeons for biology and anatomy courses. In May 2017, the supervisory department intercepted some pigeons carrying drug-filled borders across the country.

Self-driving car
Most car accidents are caused by human operations. Drive away the driver and the road will become safer. However, there is still a lot to be learned about autonomous driving technology. They must “see” and “think” in real-world road conditions and react to the surrounding environment. This may mean that the car needs to spontaneously turn around a child who suddenly runs to the street, or whether to cross the intersection when the yellow light is on. Polls show that people are nervous about taking unmanned vehicles, although some claim that under the control of robots, roads will become less dangerous. But whether or not you are ready, driverless cars are coming to us.

Let the driverless car know the main sensors of the surrounding environment –

Lidar (laser detection and measurement): A laser that emits laser light and reflects objects to measure distance. It is especially suitable for remote detection, and some systems can sense objects as close as 1,000 feet. Radars do not present blurred images, and lidars can create high-resolution three-dimensional shapes, including pedestrians, curbs, and other vehicles.

Camera: The camera is the most cost-effective of the three sensors, which excel at finding lane markers and traffic lights. But they are not as accurate as radar and lidar.

Radar: Radar uses radio waves to detect the position and velocity of other objects. The police used it to capture speeding drivers, which air traffic controllers used to track aircraft. In driverless cars, the technology can detect objects from a few feet to hundreds of feet away. But the radar could not determine the shape.

miss you……
Automated vehicles must quickly understand and react to what they see. Software and algorithms implement this. One method is through artificial intelligence neural networks, which are computer systems that mimic the human brain. These neural networks allow robotic cars to understand, react and learn from sensor data in real time.

Level of automation
In 2014, the International Automaton _lr Institute of Engineers (an association of technical experts) created a standard classification of vehicle autonomy. They range from completely controlled cars that are completely controlled by cars. Levels 1 and 2 include the Advanced Driver Assistance System (ADAS), which can help you observe your blind spots and more. Levels 3 through 5 involve the Automated Driving System (ADS), which increases the control of the robot. Level 0:

You are driving.

Level 1:

You are driving, but ADAS helps you speed up and turn.

level 2:

You are driving, but in some cases, the ADAS has full control over acceleration, braking and steering.

Level 3:

ADS has full control over the car in some cases, but you are ready to take over.

level 4:

ADS performs all driving functions in certain situations, so you don’t need to pay attention.

Level 5:

When you are driving, you are a passenger.

When the Pentagon’s Defense Advanced Research Projects Agency launched a challenge to create fully automated vehicles for the military, robotics heated up at the beginning of the 21st century. Several games were held in the deserts of California and Nevada.

Competitive market
By 2040, the annual sales of self-driving cars may exceed 33 million. Currently, only self-driving cars below level 2 are available to the public. By 2021, BMW said it will sell Class 3 autos, and Ford said it will sell Class 4 autos to consumers.

It’s all great, but the regulations in this area need to keep pace and improve. In general, the law limits vehicles on the road to level 2, although some places have opened up new roads to test vehicles of level 3 and above for Akuto personnel. The US Senate is considering a bill to provide some regulatory measures for autonomous vehicles.

Shared car companies Raffles and Uber offer self-driving travel on the streets of Boston and Pittsburgh, and they also have a driver to prevent problems.

In the meantime, save money quickly. The first generation of truly unmanned vehicles is expected to cost hundreds of thousands of dollars.

Companies planning to bring driverless cars to market include Google’s Waymo


General Motors and Lexus.

The first generation of driverless vehicles may require six digits.

Skeptical public
Would you be comfortable sitting in a driverless car? According to a 2017 study, 56% of Britons expressed discomfort because of lack of trust and concerns about safety. In March 2018, a Uber self-driving car in Tempe, Arizona, killed a woman who crossed the street, further raising public fear. Another study used machine learning to analyze more than 1 trillion social media posts and found that Americans were most afraid of being hijacked by a hacker.