One of the most counterintuitive concepts in physics is that all things fall at the same speed regardless of mass, i.e. Equivalence principle. This was most memorably illustrated in 1971 by NASA Apollo 15 astronaut David Scott while walking on the moon. he is prediction A hawk feather and a hammer simultaneously over the live TV broadcast, the two bodies hit the dirt at the same time.
there old tradition An empirical test of the weak equivalence principle, which is the basis of Albert Einstein’s general theory of relativity. In test after test for centuries, the equivalence principle has remained strong. and now microscope (MICROSatellite pour l’Observation de Principe d’Equivalence) The expedition achieved the most accurate test of the equivalent principle to date, Einstein claims again, for every last paper Published in Physical Review Letters. (Additional, related articles have appeared in a special issue of Classical and Quantitative Gravity.)
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John Philoponus, the sixth century philosopher, was the first to claim that the speed at which an object falls has nothing to do with its weight (its mass) and later became a major influence on Galileo Galilei some 900 years later. It is believed that Galileo dropped artillery shells of various groups in front of the famous Leaning Tower of Pisa in Italy, but the story is most likely made up.
Galileo she did The balls roll under inclined planes, causing the balls to roll at much slower speeds, making it easier to measure their acceleration. The balls were similar in size, but some were made of iron, others of wood, which makes their mass different. Since there was no accurate clock, Galileo had timed the balls’ travel with his heartbeat. And like Philoponus, he found that regardless of the tilt, the balls would move with the same acceleration.
Later, Galileo refined his approach with a pendulum device, measuring the period of oscillation of pendulums of different masses but of the same length. This was also the method favored by Isaac Newton around 1680, and later by Friedrich Bessel in 1832, both of which greatly improved the accuracy of measurements. Newton also recognized that the principle extends to the celestial bodies, calculating that the Earth and the Moon, as well as Jupiter and its moons, fall toward the Sun at the same rate. The Earth has an iron core, while the Moon’s core is mostly made of silicates, and their mass is completely different. After NASA lunar range laser experiments Newton’s calculations confirmed that he was indeed orbiting the Sun at the same rate.
Towards the end of the 19th century, Hungarian physicist Lorand Etvos discovered Combine the pendulum approach with torsion balancing to create the torsion of the pendulum And I used it to test the equivalence principle more accurately. This simple straight stick turned out to be accurate enough to test the equivalence principle more accurately. Torsion scales were also used in later experiments, such as the one in 1964 in which bits of aluminum and gold were used as test blocks.
Einstein cited Eötvös’ experiment to verify the equivalence principle in his 1916 paper that laid the foundation for his general theory of relativity. But general relativity works well at the macro level, but it breaks down at the subatomic level, which is where the rules of quantum mechanics begin. So physicists looked for valence violations at those quantum scales. This would be evidence of potential new physics that could help unite the two into one big theory.
One way to test equivalence on a quantum scale is to use material wave interferometry. It’s about the classic Michaelson-Morley experiment trying to detect the motion of the Earth through a medium called the luminous aether, which physicists at the time thought permeated space. In the late nineteenth century, Thomas Young Use this tool For his famous double-slit experiment to test whether light is a particle or a wave – and as we now know, light is both. The The same goes for materials.
Previous experiments with matter-wave interferometry measured the free fall of two isotopes of the same atomic element, hoping to detect subtle differences without success. In 2014, a team of physicists thought there might not be enough difference between their formulations to achieve maximum sensitivity. if she is Isotopes used Among the different elements in their version of those experiments are rubidium and potassium atoms. The laser pulses caused the atoms to fall on separate paths of recombination. The researchers observed the telltale interference pattern, indicating that the valency was still within 1 part in 10 million.
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