Hyperphysics: Hafel-Keating experiment

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The forum discussion centers on the Hafel-Keating experiment and the confusion surrounding the approximation T0 = -TS in the "Kinematic Time Shift Calculation" section. The user presents equations derived from this approximation, questioning the validity of the constant speed of light (c) being influenced by variables such as Earth's rotation and radius. The discussion concludes that a proper explanation of the Hafel-Keating experiment necessitates General Relativity (GR) rather than Special Relativity (SR), emphasizing the need for integrating proper time (τ) from the Schwarzschild metric.

PREREQUISITES
  • Understanding of Special Relativity (SR) and General Relativity (GR)
  • Familiarity with the Hafel-Keating experiment
  • Knowledge of the Schwarzschild metric in general relativity
  • Basic grasp of kinematic equations and time dilation concepts
NEXT STEPS
  • Study the implications of the Hafel-Keating experiment in the context of General Relativity
  • Learn about the Schwarzschild metric and its applications in time dilation
  • Explore the differences between Special Relativity and General Relativity
  • Investigate the mathematical derivations of proper time (τ) in relativistic physics
USEFUL FOR

Physicists, students of relativity, and anyone interested in the implications of time dilation in rotating reference frames will benefit from this discussion.

Rasalhague
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http://hyperphysics.phy-astr.gsu.edu/HBASE/relativ/airtim.html#c5

I don't understand the approximation T0 = -TS that they make in the final step of the section "Kinematic Time Shift Calculation". From this, and the other equations in this section, I get

[tex]-T_0=T_0\left ( 1+\frac{R^2\omega^2}{2c^2} \right )[/tex]

[tex]-1=1+\frac{R^2\omega^2}{2c^2}[/tex]

[tex]c^2=\frac{R^2\omega^2}{-4}[/tex]

[tex]c=\pm \frac{R\omega}{2i}[/tex]

but how can this be when c is a constant positive real number, not dependent on the product of the rotation of the Earth with its radius? And

[tex]T_A=T_S-T_S\left ( \frac{2R\omega v+v^2}{2c^2} \right )[/tex]

[tex]T_0\left ( 1+\frac{R^2\omega^2}{2c^2} \right )=-T_S\left ( -1+ \frac{2R\omega v+v^2}{2c^2} \right )[/tex]

[tex]T_0\left ( 1+\frac{R^2\omega^2}{2c^2} \right )=T_0\left ( -1+ \frac{2R\omega v+v^2}{2c^2} \right )[/tex]

[tex]4c^2= 2R\omega v+v^2 - R^2\omega^2[/tex]

[tex]c=\frac{\sqrt{(R\omega+v)^2-2R^2\omega}}{2}[/tex]

which can't be right, since c doesn't depend on these arbitrary variables: radius of the earth, etc.
 
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Rasalhague said:
http://hyperphysics.phy-astr.gsu.edu/HBASE/relativ/airtim.html#c5

I don't understand the approximation T0 = -TS that they make in the final step of the section "Kinematic Time Shift Calculation". From this, and the other equations in this section, I get

[tex]-T_0=T_0\left ( 1+\frac{R^2\omega^2}{2c^2} \right )[/tex]

[tex]-1=1+\frac{R^2\omega^2}{2c^2}[/tex]

[tex]c^2=\frac{R^2\omega^2}{-4}[/tex]

[tex]c=\pm \frac{R\omega}{2i}[/tex]

but how can this be when c is a constant positive real number, not dependent on the product of the rotation of the Earth with its radius? And

[tex]T_A=T_S-T_S\left ( \frac{2R\omega v+v^2}{2c^2} \right )[/tex]

[tex]T_0\left ( 1+\frac{R^2\omega^2}{2c^2} \right )=-T_S\left ( -1+ \frac{2R\omega v+v^2}{2c^2} \right )[/tex]

[tex]T_0\left ( 1+\frac{R^2\omega^2}{2c^2} \right )=T_0\left ( -1+ \frac{2R\omega v+v^2}{2c^2} \right )[/tex]

[tex]4c^2= 2R\omega v+v^2 - R^2\omega^2[/tex]

[tex]c=\frac{\sqrt{(R\omega+v)^2-2R^2\omega}}{2}[/tex]

which can't be right, since c doesn't depend on these arbitrary variables: radius of the earth, etc.

HK is poorly explained using SR, a correct explanation requires GR. I am quite sure that I gave a GR-based explanation for HK somewhere in this forum. It is simply calculating the proper time [tex]\tau[/tex] by integrating the expression in coordinate time t. The expression can be derived straight from the general Schwarzschild metric setting:

[tex]dr=d\theta=0[/tex],
[tex]\frac{d\phi}{dt}=\omega +\frac{v_1}{R}[/tex]
[tex]\frac{d\phi}{dt}=\omega -\frac{v_2}{R}[/tex]

depending on the direction of plane motion
 
Last edited:

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