The speed limit of human beings

Mark Denny of Stanford University in the United States has made an in-depth study on how fast humans can run 100 meters. By analyzing the world records of various track and field competitions since 1920, he found that the results of many competitions followed a similar law, that is, the results gradually improved until they were stable. According to his prediction, the limit of men's 100-meter performance is 9.48 seconds, which is only 0. 1 second less than Bolt's current world record. Danny said: "If we continue to maintain the current momentum, Bolt will soon be close to this limit." What is the reason? Danny believes that the reason for human speed limit is similar to the strength-to-weight ratio of athletes. Beyond a certain point, the advantages of stronger muscles and longer limbs will be offset by the increased energy consumption of lifting heavier objects.

2. How long can human attention last?

For those who need to concentrate on a certain job, such as truck drivers, power plant operators and flight drivers, 12 hours is a limit. However, for doctors, complicated operations sometimes exceed 12 hours, although the longest operation is often shared by multiple teams. Before 2004, British doctors in weekend classes had to work 80 hours from Friday morning to Sunday night.

3. How long can people live in a vacuum?

197 1 year, just before the Soviet spacecraft 1 1 re-entered the earth's atmosphere, a faulty valve suddenly depressurized the spacecraft at the altitude of 168 km, resulting in the death of all three astronauts on board. After investigation, it was found that the pressure of Soyuz spacecraft 1 1 suddenly dropped to zero and lasted for 1 1 min for 40 seconds until it re-entered the atmosphere.

The astronaut died after 30 to 40 seconds due to lack of oxygen. Jonathan Clark, a former crew member of NASA's space shuttle mission, said, "You need oxygen and air pressure to transport oxygen to your brain." However, if you spend less time in a vacuum, you may be saved. 1966, a technician from NASA was testing the spacesuit in the vacuum chamber when the indoor air pressure suddenly dropped to the level we encountered at an altitude of 36,500 meters. He lost consciousness within 12 to 15 seconds.

The last thing he can remember is that the saliva on his tongue evaporated, because water will evaporate at low pressure. Within 27 seconds, the pressure in the vacuum chamber returned to the level equivalent to 4200 meters, and the technician was lucky to regain consciousness. Although he looks pale, his health has not been adversely affected.

4. How many things can humans remember?

Lv Chao of China, the current world memory champion, was able to recite pi of 67,890 in 2005. Our ability to receive information is quite strong. Thomas Randall worked in Bell Communication Research Company in Morristown, New Jersey from 65438 to 0986. He studied how much visual and verbal information people can store when they look at pictures and information, and how quickly they forget. After research, he estimated that adults can store about 125M of this information in their lifetime, which is equivalent to 100 Mobidick.

5. How low temperature can humans tolerate?

Mike Tipton, who studies human body temperature regulation at Portsmouth University in England, points out that all of us can still live without the means of keeping out the cold-clothes, heating and houses. Living in the cold is to protect the core body temperature. People's core body temperature is 37 degrees Celsius, but the speed of its decline is surprising. Fran Oshaman, a physiologist at the University of Ottawa in Canada, said that if the weather is humid and windy, the ambient temperature of 20 degrees Celsius will lead to hypothermia. When it is cold, the body begins to tremble and blood stops flowing to the limbs. Hypothermia will occur as long as the core body temperature drops by 2 degrees: first, people begin to lose consciousness, and then their heart rate will drop. At about 24 degrees, the heart will stop beating and people will die. However, some people can survive with a significant drop in core body temperature. Anna Ba Gen's family is such a person. Her temperature dropped to 13.7 degrees Celsius, and she was still alive. At that time, she accidentally fell into a cold current and was trapped for 80 minutes before being rescued.

6. How long can you live without eating or drinking?

Theoretically, if you finally run out of fat, protein and carbohydrates, your body will stop working because of energy exhaustion. Jeremy Powell Kurt, a nutrition guidance doctor who resumed eating after the hunger strike in david brian, London in 2003, believes that people don't have to wait until their energy is completely exhausted: "You may have died before." If there are enough water-soluble B vitamins in the body to help store fat metabolism, fat people may live longer. So it is entirely possible that people starve to death or have fat. The longest record of not eating was Kieran Doherty, an Irish hunger strike protester in 198 1 year, who died after 73 days of hunger strike. With vitamins and water supplements, people can live for a year without eating. Powell Teke said, "This is a very popular way to lose weight about 30 years ago."

7. How long can humans last without sleep?

1On February 28th, 963, Randy Gardner, a 0/7-year-old student in San Diego, California, got up at 6 am. He felt energetic and didn't fall asleep again until1June 8, 964, which means he had 1 1 day. After Gardner broke the previous record of 260 hours of sleepless, his record of 264 hours is still the longest sleepless time verified by science. William Dement, a researcher at Stanford University School of Medicine in California, told this story in a paper at 1965. He spent the last three days with Gardner.

Gardner experienced mood swings, memory and attention problems, lack of coordination, slurred speech and hallucinations, but he was otherwise normal. One day after 1 1, his first sleep only lasted 14 hours. According to Dement, Gardner did not take stimulants during this sleepless period. But someone was with him to keep him awake. If there is no help from others, you must try to restrain yourself from going to sleep after 36 hours, and you will feel irresistible to sleep after 48 hours.

8. How much gravity acceleration can ordinary people bear?

When the roller coaster swoops down, it will bear 5g gravity acceleration in a short time, and then it will be dizzy and disgusting. These seats must be specially designed so that people will not faint. The ability to withstand gravity acceleration depends not only on the change and duration of acceleration or deceleration, but also on the direction of the body. It is most sensitive to external forces applied in the direction of the feet, because it makes blood flow to the brain. When the body is in a vertical state for 5 to 10 seconds in an environment of 4 to 5g, it often causes tubular vision and then loses consciousness.

The gravity acceleration of the fighter plane in the vertical state can reach 9g. The stronger the pilot's tolerance to this environment, the better it is for air combat. Some pilots wear "gravity acceleration suits" to prevent the blood in their legs from rushing to their heads. The person who has the strongest ability to bear gravity is called "monster G". Alec Stevenson, a biologist at Qinetiq, a British-based defense company, said, "Some of us can really stay awake in a 6g environment." Others will pass out in the 3g environment.

Pilots can improve their natural tolerance to gravity by training in centrifuges. Qinetiq has such a centrifuge in Farnborough, Hampshire, England. They learn to tighten leg and abdominal muscles, promote blood flow to the upper body, and lower blood pressure through special breathing methods. The maximum gravity that a person can bear is 3 1.25g, but in order to achieve this goal, a doctor from NASA, Flanagan Gray, entered a special water tank, which exerted pressure on his body and helped him to bear such a large gravity acceleration. John stapp, the pioneer of American Air Force, holds the highest record of horizontal gravity acceleration.

9. How high can humans climb?

The difference in altitude will have a strange effect on the human body. In most cases, the oxygen pressure in the air at high altitude will decrease. Human cells need oxygen to survive. At higher altitudes, hemoglobin, the blood protein that transports oxygen from the lungs to cells, cannot effectively transport oxygen, leading to hypoxia in the human body. The brain is very sensitive to oxygen level, which is also the first reaction of altitude sickness and the cause of headache and dizziness. Mike Glocott of the University of Southampton in the United Kingdom said that if people stay at an altitude of more than 5,000 meters for a long time, the risk of muscle atrophy and lung and hydrocephalus will increase significantly, but they may not be able to give birth there, because high altitude temporarily inhibits male fertility. Glocott studied the effect of altitude difference on physiology.

1999, the Sherpas of Babu Chiri lived in the anoxic environment of Mount Everest for 2 1 hour, breaking the world record. Glocott said, maybe ChirishSherpa people are born with the ability to adapt to high altitude environment. How high can humans live? Maybe Everest is close to this height. Glocott said that so far, only one person has climbed Mount Everest without an oxygen device in winter, when the atmospheric pressure dropped even lower and there was less oxygen in the air. "I think the highest altitude that humans can bear may be 9000 meters."

10. How much weight can humans lift at most?

The world weightlifting record was set by British weightlifter Andy Bolton. He lifted the weight of 457.5 kilograms from the ground to his thigh. Dan Wasser, a sports coach at Youngstown State University in Ohio, said that a strongman like Bolton may be five or six times stronger than ordinary people, and it is already difficult for ordinary people to lift 45 kilograms above their heads. The overhead weightlifting record is 263.5 kg.

Todd Scud of the University of Southern California in Los Angeles believes that we are close to the limit we can reach. He said: "Looking back at the previous weightlifting records, we will find that although the performance has been continuously improved, it has begun to reach a stable level. Today's weightlifters, including those who take steroids, are close to the limits of human physical fitness. "

1 1. How much radiation can the human body bear at most?

1987 In September, two men walked into an abandoned clinic in Iania, Brazil, and removed a piece of equipment that they thought was very valuable. Within one day, both of them had vomiting symptoms, followed by diarrhea and dizziness. As everyone knows, this abandoned equipment is actually a high radiation source, which is used to treat cancer patients.

This radiation source can emit blue light in the dark. Deval Ferrera, a scrap dealer, became interested in it and finally bought it. Ferreira put a cup-sized jar containing powdered substances in the restaurant and invited friends and relatives to visit. They powdered themselves and turned themselves into luminous people. But what they never expected was that this magical powder turned out to be radioactive cesium chloride. Within a month, Ferreira's wife, 6-year-old niece and 2 employees all died of acute radiation syndrome. In this accident, a total of 249 people were polluted by this radioactive substance.

The unit of radiation dose is sievert, which is calculated according to the type of radiation and the body part to be irradiated. The calculation results show that the radiation dose received by all the deceased in a few days is 4.5 to 6 sieverts. The average annual radiation dose of natural radiation sources such as radon is 2.4 millisieverts. In other words, 4.5 to 6 sieverts is already a considerable dose.

12. How long can humans hold their breath?

Most people find it difficult to hold their breath for more than a minute. In contrast, the Frenchman Stefan Mifusu has super self-control. On June 8, 2009, Mifsu made a feat, holding his breath for 1 1 min 35 seconds, setting a new world record for holding his breath still.

In the challenge, the contestants soaked their faces in a cold pool. This is not to prevent them from cheating, but to arouse the instinctive diving reflex of mammals. When the face is soaked in cold water, the external blood vessels contract and blood flows from the limbs to the heart and brain. This will slow down the heart rate and reduce the chance of oxygen spreading to the whole body. After training, the heart rate of breath-holding masters when immersed in cold water is only half that of non-divers.

John anderson, a physiologist at Lund University in Sweden, gave a negative answer. The physiologist, who has been studying the effects of breath holding, said: "Before the breath holding record becomes stable, excellent divers are expected to extend the breath holding time to about 15 minutes."