Researchers confirmed a basic assumption in physics with unprecedented accuracy — that the different properties of masses, such as weight, inertia and gravity, are always equivalent, regardless of the specific composition of the masses involved. It reinforces the equivalence principle, which is essential to Einstein’s theory of relativity, and addresses the critical point of difference between classical physics and quantum physics.
The research team from Leibniz University Hannover and the University of Bremen confirmed another principle of equality.
Scientists have used half a century of lunar laser range data to confirm with 100 times greater accuracy that all the properties of mass are the same. This finding strongly supports Einstein’s equivalence principle, which is the cornerstone of the theory of relativity.
One of the most fundamental assumptions of fundamental physics is that the different properties of mass—weight, inertia, and gravity—always remain the same. Without this equivalence, Einstein’s theory of relativity would be contradictory and existing physics textbooks would have to be rewritten. Although all measurements to date confirm the equivalence principle, quantum theory holds that there must be a violation. It is this difference between Einstein’s theory of gravity and modern quantum theory that is why more rigorous testing of the equivalence principle is so important.
Sebuah tim dari Center for Applied Space Technology and Microgravity (ZARM) di University of Bremen, bekerja sama dengan Institute for Geodesy (IfE) di Leibniz University Hannover, berhasil menunjukkan bahwa ukurannya 100 kali lebih besar.[{”attribute=””>accuracythatpassivegravitationalmassandactivegravitationalmassarealwaysequivalent–regardlessoftheparticularcompositionoftherespectivemassesTheresearchwasconductedwithintheframeworkoftheClusterofExcellence“QuantumFrontiers”OnJuly13theteampublishedtheirfindingsasahighlightsarticleinthescientificjournal[{”attribute=””>accuracythatpassivegravitationalmassandactivegravitationalmassarealwaysequivalent–regardlessoftheparticularcompositionoftherespectivemassesTheresearchwasconductedwithintheframeworkoftheClusterofExcellence“QuantumFrontiers”OnJuly13theteampublishedtheirfindingsasahighlightsarticleinthescientificjournalPhysical Review Letters.
Binary system Earth-Moon. Credit: AEOS Medialab, ESA 2002
Physical context
Inertial mass resists acceleration. For example, it causes you to be pushed backward into your seat when the car starts. Passive gravitational mass reacts on gravity and results in our weight on Earth. Active gravitational mass refers to the force of gravitation exerted by an object, or more precisely, the size of its gravitational field. The equivalence of these properties is fundamental to general relativity. Therefore, both the equivalence of inertial and passive gravitational mass and the equivalence of passive and active gravitational mass are being tested with increasing precision.
First Author of the Publication, Vishwa Vijay Singh. Credit: Singh
What was the study about?
If we assume that passive and active gravitational mass are not equal – that their ratio depends on the material – then objects made of different materials with a different center of mass would accelerate themselves. Since the Moon consists of an aluminum shell and an iron core, with centers of mass offset against each other, the Moon should accelerate. This hypothetical change in speed could be measured with high precision, via “Lunar Laser Ranging.” This involves pointing lasers from Earth at reflectors on the Moon placed there by the Apollo missions and the Soviet Luna program. Since then, round trip travel times of laser beams are recorded. The research team analyzed “Lunar Laser Ranging” data collected over a period of 50 years, from 1970 to 2022, and investigated such mass difference effects. Since no effect was found, this means that the passive and active gravitational masses are equal to approximately 14 decimal places. This estimate is a hundred times more accurate than the best previous study, dating back to 1986.
Unique expertise
LUH’s Institute of Geodesy – one of only four centers worldwide analyzing laser distance measurements to the Moon – has unique expertise in assessing the data, particularly for testing general relativity. In the current study, the institute analyzed the Lunar Laser Ranging measurements, including error analysis and interpretation of the results.
Vishwa Vijay Singh, Jürgen Müller and Liliane Biskupek from the Institute of Geodesy at Leibniz University Hannover, as well as Eva Hackmann and Claus Lämmerzahl from the Center of Applied Space Technology and Microgravity (ZARM) at the University of Bremen published their findings in the journal Physical Review Letterswhere the paper was highlighted in the category “editors’ suggestion.”
Reference: “Equivalence of Active and Passive Gravitational Mass Tested with Lunar Laser Ranging” by Vishwa Vijay Singh, Jürgen Müller, Liliane Biskupek, Eva Hackmann and Claus Lämmerzahl, 13 July 2023, Physical Review Letters.
DOI: 10.1103/PhysRevLett.131.021401
2023-07-16 15:33:12
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