Abstract
The Equivalence Principle (EP) is the pillar that general relativity stands on. The three formulations of the EP, Weak, Einstein and Strong are stated and discussed. We describe the experimental verifications of the Universality of Free Fall, from Eötvös’ balances to the measurement in the microgravity of microscope, that sets, as of today, the best confirmation of EP.
The original version of this chapter was revised: Chapter have been updated with the correction. The correction to this chapter can be found at https://doi.org/10.1007/978-3-030-95596-0_15
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11 April 2023
In original version of the book, the following belated corrections received from the author have been incorporated in respective chapters and Appendix at backmatter.
Chapter 2
Equation 2.27 has been removed and remaining equations are renumbered
Figure 2.8 has been replaced with revised figure
Chapter 7
In Equation 7.20 “(TT)” has been removed from equation
In page 161 the in line equation modified (\( 10^{11} - 10^{15}\) T) to (\( 10^{7} - 10^{11}\) T)
Chapter 9
In Page 215, few lines has been replaced with updated as in below:
From
“In the DL case this difference may be due to different values of the curvature radii of the mirrors of the two cavities while in the FP interferometer, different values of finesse in the two FP cavities, or due to differences in either the radius of curvature or the reflectivity of the mirrors, so one can place even more demanding conditions on the reduction of frequency noise of laser light.”
To
“This difference is due, in both cases, to asymmetries in the practical implementation of the two arms: unequal curvature radii for the DL, unequal finesse (that depends on both the curvature radius and the reflectivity of the mirrors) in the case of the FP cavities. This asymmetry places even more demanding conditions on the reduction of frequency noise of laser light.” In page 218 line has been removed “Although an entire chapter of this text is devoted to it”
In addition, some minor corrections have been made throughout the book that does not change the basic facts.
The correction chapters and the book has been updated with the changes.
Notes
- 1.
See chapter Modulation Techniques.
- 2.
This condition only holds for the Fourier components that lay within the characteristic frequency range of the control system.
- 3.
A magneto-optic trap (MOT) is a sophisticated apparatus where atoms are slowed down (to energies corresponding to \(\mu K\)) by elastic collisions with photons of laser beams; these “cold” atoms are then trapped by magnetic field, through the Zeeman effect, in a small region of space: localized clouds of up to \(10^8\) atoms can be generated and maintained indefinitely. The techniques of laser cooling were awarded a Nobel prize for physics in 1997.
- 4.
The Superconducting Quantum Interference Device (SQUID) is a very sensitive magnetometer based on the Josephson effect. It is described in Sect. 8.2.5.
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Ricci, F., Bassan, M. (2022). The Equivalence Principle. In: Experimental Gravitation. Lecture Notes in Physics, vol 998. Springer, Cham. https://doi.org/10.1007/978-3-030-95596-0_3
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