Related Experiment Video
Updated: Mar 7, 2026
10:42
Preparing an Isotopically Pure 229Th Ion Beam for Studies of 229mTh
Published on: May 3, 2019
7.4K
Varying Constants, Gravitation and Cosmology
1Institut d'Astrophysique de Paris, UMR-7095 du CNRS, Université Pierre et Marie Curie, 98 bis bd Arago, 75014 Paris, France ; Department of Mathematics and Applied Mathematics, Cape Town University, Rondebosch, 7701 South Africa ; National Institute for Theoretical Physics (NITheP), Stellenbosch, 7600 South Africa.
Living Reviews in Relativity
|February 10, 2017
Summary
Fundamental constants are crucial to physical laws. Testing their constancy is vital for understanding gravity and general relativity, with various experiments providing key constraints.
Area of Science:
- Physics
- Cosmology
- Astrophysics
Background:
- Fundamental constants underpin physical laws.
- Variations in constants suggest new physics, potentially violating the universality of free fall.
- Testing constant stability is crucial for validating general relativity.
Purpose of the Study:
- To detail the relationships between fundamental constants.
- To review experimental and observational constraints on constant variation.
- To explore theoretical frameworks for varying constants.
Main Methods:
- Analysis of atomic clocks, Oklo phenomenon, solar system observations, meteorite dating, quasar spectra, stellar physics, pulsar timing, CMB, and Big Bang Nucleosynthesis.
- Examination of local position invariance and universality of free fall tests.
- Review of theoretical models linking constant variations and unification mechanisms.
Main Results:
- Compilation of experimental and observational constraints on the constancy of fundamental constants.
- Identification of systematic effects and limitations in current tests.
- Discussion of theoretical frameworks predicting potential variations.
Conclusions:
- The constancy of fundamental constants is rigorously tested across diverse astrophysical and terrestrial systems.
- Current data place stringent limits on potential variations, supporting the standard model of cosmology.
- Further research explores theoretical implications and the fine-tuning problem of constant values.
Related Concept Videos
01:15Newton's Law of Gravitation
17.3K
Our everyday observation tells us that all objects close to the Earth naturally tend to fall to the ground. Early philosophers assumed that this downward force was unique to Earth. By the 16th century, Nicolaus Copernicus (1473-1543) put forward the heliocentric theory, which suggested that Earth and other planets orbited the sun, while the Moon orbited the Earth. However, it was Isaac Newton (1642-1727) who linked these two motions together in the 17th century. He reasoned that the force of...
17.3K
01:16Gravitation
9.6K
In the years before Newton, a general belief prevailed that different laws governed objects in the sky than objects on Earth. When Kepler wrote down the three laws of planetary motion, explaining in detail the geometrical properties of the planetary orbits around the Sun, there was no immediate idea to discern their connection with more fundamental laws. It was Isaac Newton who, in 1665–66, figured out the connection between planetary motion, the motion of the moon around the Earth, and...
9.6K
01:18Principle of Equivalence
2.6K
According to Albert Einstein (1897-1955), free-falling and feeling weightless are intrinsically linked. If a person were in free-fall under gravity, for example, diving towards the Earth from an airplane, they would feel completely weightless. Similarly, a person descending in a lift may feel partially weightless. Broadly speaking, it is assumed that an object in a uniform gravitational field and an object undergoing constant acceleration in the absence of gravity are under the same...
2.6K
01:24Newton's Law of Gravitational Attraction
1.7K
Sir Isaac Newton established the universality of the law of gravitational attraction based on empirical evidence and inductive reasoning. He published his work in Philosophiae Naturalis Principia Mathematica ("the Principia") on July 5, 1687.
Newton's law of gravitational attraction is a fundamental law of physics that governs the attraction between objects. It states that the magnitude of the gravitational force between any two objects is proportional to their masses and inversely...
Newton's law of gravitational attraction is a fundamental law of physics that governs the attraction between objects. It states that the magnitude of the gravitational force between any two objects is proportional to their masses and inversely...
1.7K
01:14Gravitation Between Spherically Symmetric Masses
1.4K
The gravitational potential energy between two spherically symmetric bodies can be calculated from the masses and the distance between the bodies, assuming that the center of mass is concentrated at the respective centers of the bodies.
1.4K
01:20Variation in Acceleration due to Gravity near the Earth's Surface
2.9K
An object's apparent weight is its weight measured by a spring balance at its location. It is different from its true weight, the force with which the Earth pulls it, because of the Earth's rotation. Mathematically, an object's apparent weight equals its true weight minus the centripetal force that keeps it in a circular motion along with the Earth's surface every 24 hours.
The difference between the true and apparent weights is proportional to the square of the Earth's...
The difference between the true and apparent weights is proportional to the square of the Earth's...
2.9K