The history of the barometer (and how it works) - Asaf Bar-Yosef

Recent questions

• What is a true vacuum?

  A true vacuum is a space devoid of matter, meaning it has no particles, air, or any form of substance within it. The concept of a true vacuum has been debated in scientific circles, particularly since Aristotle claimed that such a state could not exist. This assertion was challenged in the 17th century when experiments revealed that a vacuum could be created under certain conditions, leading to a deeper understanding of air pressure and the behavior of gases. The exploration of vacuums has significant implications in various scientific fields, including physics and meteorology, as it relates to the behavior of air and the principles governing atmospheric pressure.

• How does atmospheric pressure work?

  Atmospheric pressure is the force exerted by the weight of air above a given point, typically measured in units such as pascals or millibars. It varies with altitude; as one ascends, the amount of air above decreases, leading to lower pressure. This phenomenon was notably observed by Blaise Pascal, who noted that mercury levels in barometers decreased with altitude, illustrating the relationship between air pressure and elevation. Understanding atmospheric pressure is crucial for various applications, including weather forecasting, aviation, and understanding natural phenomena. The foundational experiments conducted in the 17th century laid the groundwork for our current understanding of how atmospheric pressure operates.

• What is a barometer?

  A barometer is an instrument used to measure atmospheric pressure, which is essential for weather prediction and understanding environmental conditions. The invention of the barometer is attributed to Evangelista Torricelli, who created a device using mercury to replace water, allowing for a more compact and efficient measurement due to mercury's higher density. The standard mercury barometer typically features a column of mercury approximately 76 centimeters high, which correlates with standard atmospheric pressure at sea level. Barometers have evolved over time, but the principles established in the 17th century remain integral to meteorology and atmospheric science.

• Who was Evangelista Torricelli?

  Evangelista Torricelli was an Italian physicist and mathematician best known for his contributions to the understanding of atmospheric pressure and the invention of the barometer. Born in 1608, Torricelli was a student of Galileo and built upon the work of earlier scientists, such as Gasparo Berti, who demonstrated the creation of a vacuum. Torricelli's pivotal experiment involved using mercury instead of water in a barometer, which allowed for a more accurate and compact measurement of atmospheric pressure. His work laid the foundation for modern meteorology and significantly advanced the scientific community's understanding of air pressure and its effects on weather phenomena.

• What did Blaise Pascal discover?

  Blaise Pascal was a French mathematician, physicist, and inventor who made significant contributions to the understanding of fluid mechanics and atmospheric pressure. One of his key discoveries was the observation that mercury levels in barometers decrease with altitude, which provided empirical evidence supporting the relationship between air pressure and elevation. This finding was crucial in validating the theories proposed by earlier scientists, including Torricelli, and helped establish the principles of hydrostatics. Pascal's work not only advanced scientific knowledge in the 17th century but also laid the groundwork for future studies in physics and engineering, influencing various fields that rely on the principles of pressure and fluid dynamics.