爱因斯坦的相对论在量子挑战后仍然强大

汉诺威莱布尼茨大学和不来梅大学的研究小组证实了另一个等效原理。

科学家们利用半个世纪的月球激光测距数据，以 100 倍的精度确认所有质量特性都是相等的。 这一发现极大地支持了爱因斯坦的等效原理，该原理是相对论的基石。

基础物理学最基本的假设之一是质量的不同属性——重量、惯性和重力——彼此之间总是保持相同。 如果没有这种等价性，爱因斯坦的相对论将是矛盾的，现有的物理教科书将不得不重写。 尽管迄今为止的所有测量都证实了等效原理，但量子理论认为一定存在违反。 爱因斯坦引力理论与现代量子理论之间的这种差异是为什么对等效原理进行更严格的测试尤为重要的原因。

不来梅大学应用空间技术和微重力中心 (ZARM) 的一个团队与汉诺威莱布尼茨大学大地测量研究所 (IfE) 合作，成功证明了它的尺寸扩大了 100 倍。[{” attribute=””>accuracy that passive gravitational mass and active gravitational mass are always equivalent – regardless of the particular composition of the respective masses. The research was conducted within the framework of the Cluster of Excellence “QuantumFrontiers.” On July 13, the team published their findings as a highlights article in the scientific journal Physical 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 Letters, where 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