Two iron balls of different sizes were thrown from the Leaning Tower of Pisa, and they landed at the same speed at the same time. More than 400 years ago, the Italian scientist Galileo Galilei completed the famous free fall experiment. Today, the gravity of the China Institute of Metrology The instrument research team can also experience it. Unlike Galileo, however, the objects they observed were not balls of iron, but clusters of atoms.
The gravimeter research team is one of the nine frontier research teams of metrology basics of the China Metrology Institute. The team's work is to accurately measure the acceleration of gravity, establish a national standard system for the measurement of acceleration of gravity, and develop self-controllable precision measuring instruments for this purpose—— Absolute gravimeter.
Ga, the unit of gravitational acceleration, is named in honor of Galileo. Compared with Galileo’s time, the measurement uncertainty of 3.0 and 4.6 microGal is equivalent to improving the measurement accuracy of gravitational acceleration by nearly 7 orders of magnitude, that is, 10 to the 7th power, tens of millions of times.
This is the development of the times and the progress of science and technology. Galileo may not have imagined that in a few hundred years, people can use atomic interference absolute gravimeters to replace free-falling objects from macroscopic objects to microscopic atomic clusters, and use laser cooling and manipulation technology to measure gravitational acceleration in an ultra-high vacuum environment.
More than that. The China Institute of Metrology also uses the self-developed laser interferometric and atomic interferometric absolute gravimeters, and by hosting international comparisons and superconducting gravitational observation technologies, it has established a national gravitational acceleration measurement benchmark that is corroborated by different technical systems. better than 1 microGal.
In 2017, 32 gravimetric instruments from 14 countries gathered at the China Metrology Institute to carry out a "big contest" - metrology comparison. The absolute gravimeter of the China Institute of Metrology performed well, making the origin of the global gravimetric benchmark settled in China. The so-called origin is the point with the highest measurement accuracy of the global gravitational acceleration, and it is also the source of the global gravitational acceleration value. Previously, the origin of the global gravimetric reference has been in Europe.
"This means that China has become the source of the global gravitational acceleration value traceability, and has carried out the gravitational acceleration value traceability and transmission for the world, demonstrating my country's scientific and technological strength and international influence in the global metrology community." Deputy of the Institute of Time and Frequency, China Metrology Institute Wu Shuqing, director and leader of the gravimeter research team, is very proud.
Researchers always pursue the ultimate, and the pursuit of higher precision is not only a self-breakthrough, but also a practical need. Such a high-precision gravimeter is useful in real life.
Affected by the earth's gravity, objects have almost the same gravitational acceleration when falling, but under the influence of factors such as different latitudes and changes in mineral deposits in the stratum, the gravitational acceleration will change slightly. This change is an important basis for auxiliary navigation, resource exploration, earthquake prediction, and ocean monitoring.
For example, positioning and navigation means can be obtained by matching gravity signals at different locations with standard gravity maps. According to anomalies or sudden changes in the gravity field, resources can be explored and what kind of resources are determined. Researchers have used gravity measurements to find out the shape, location and depth of the underground tombs of the Ming Tombs in Beijing. The accuracy of the electronic scales we use in our lives is also based on accurate gravity measurements...
As the country's basic data and strategic data, the precise measurement of gravitational acceleration has never stopped. In recent years, the absolute gravimeter can be seen in major national engineering projects such as the "China Continental Scientific Drilling Project", "China Continental Tectonic Environment Monitoring Network", "Polar Scientific Research", "Precision Gravity Measurement National Major Science and Technology Infrastructure Construction" and so on. figure. "They are 'doing CT' for the earth more accurately, allowing us to understand the homeland of human beings more and more." The gravimeter research team of the China Metrology Institute described it.
(Original title "Sunshine Our Country's Heavy Weapon 34")
The gravimeter research team is one of the nine frontier research teams of metrology basics of the China Metrology Institute. The team's work is to accurately measure the acceleration of gravity, establish a national standard system for the measurement of acceleration of gravity, and develop self-controllable precision measuring instruments for this purpose—— Absolute gravimeter.
The optical interferometric absolute gravimeter independently developed by the Chinese Academy of Metrology participated in the international comparison. Data map
The measurement of gravitational acceleration is divided into absolute gravity measurement and relative gravity measurement. The Chinese Institute of Metrology has been researching absolute gravimeters for more than half a century. Since 2013, they have carried out concentrated research on a new generation of laser interferometric absolute gravimeters and the first generation of atomic interferometric absolute gravimeters, breaking through more than ten "neck stuck" technologies, and greatly improving the measurement level of gravitational acceleration. The combined standard uncertainty of the two absolute gravimeter measurements is 3.0 and 4.6 μGal, respectively.Ga, the unit of gravitational acceleration, is named in honor of Galileo. Compared with Galileo’s time, the measurement uncertainty of 3.0 and 4.6 microGal is equivalent to improving the measurement accuracy of gravitational acceleration by nearly 7 orders of magnitude, that is, 10 to the 7th power, tens of millions of times.
This is the development of the times and the progress of science and technology. Galileo may not have imagined that in a few hundred years, people can use atomic interference absolute gravimeters to replace free-falling objects from macroscopic objects to microscopic atomic clusters, and use laser cooling and manipulation technology to measure gravitational acceleration in an ultra-high vacuum environment.
More than that. The China Institute of Metrology also uses the self-developed laser interferometric and atomic interferometric absolute gravimeters, and by hosting international comparisons and superconducting gravitational observation technologies, it has established a national gravitational acceleration measurement benchmark that is corroborated by different technical systems. better than 1 microGal.
In 2017, 32 gravimetric instruments from 14 countries gathered at the China Metrology Institute to carry out a "big contest" - metrology comparison. The absolute gravimeter of the China Institute of Metrology performed well, making the origin of the global gravimetric benchmark settled in China. The so-called origin is the point with the highest measurement accuracy of the global gravitational acceleration, and it is also the source of the global gravitational acceleration value. Previously, the origin of the global gravimetric reference has been in Europe.
"This means that China has become the source of the global gravitational acceleration value traceability, and has carried out the gravitational acceleration value traceability and transmission for the world, demonstrating my country's scientific and technological strength and international influence in the global metrology community." Deputy of the Institute of Time and Frequency, China Metrology Institute Wu Shuqing, director and leader of the gravimeter research team, is very proud.
Researchers always pursue the ultimate, and the pursuit of higher precision is not only a self-breakthrough, but also a practical need. Such a high-precision gravimeter is useful in real life.
Affected by the earth's gravity, objects have almost the same gravitational acceleration when falling, but under the influence of factors such as different latitudes and changes in mineral deposits in the stratum, the gravitational acceleration will change slightly. This change is an important basis for auxiliary navigation, resource exploration, earthquake prediction, and ocean monitoring.
For example, positioning and navigation means can be obtained by matching gravity signals at different locations with standard gravity maps. According to anomalies or sudden changes in the gravity field, resources can be explored and what kind of resources are determined. Researchers have used gravity measurements to find out the shape, location and depth of the underground tombs of the Ming Tombs in Beijing. The accuracy of the electronic scales we use in our lives is also based on accurate gravity measurements...
As the country's basic data and strategic data, the precise measurement of gravitational acceleration has never stopped. In recent years, the absolute gravimeter can be seen in major national engineering projects such as the "China Continental Scientific Drilling Project", "China Continental Tectonic Environment Monitoring Network", "Polar Scientific Research", "Precision Gravity Measurement National Major Science and Technology Infrastructure Construction" and so on. figure. "They are 'doing CT' for the earth more accurately, allowing us to understand the homeland of human beings more and more." The gravimeter research team of the China Metrology Institute described it.
(Original title "Sunshine Our Country's Heavy Weapon 34")
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