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Strong Equivalence Principle of Gravitation
by Ron Kurtus (16 December 2018)
The Strong Equivalence Principle of Gravitation (also known as the Einstein Equivalence Principle) states that the effects of acceleration are indistinguishable from those of gravitation.
In other words, the principle extends the equivalence of masses to state that observations of acceleration cannot be distinguished from gravity.
(See Artificial Gravity for an example of this.)
Questions you may have include:
- What can experiments can be done by the observer?
- What was Einsteins conclusion?
- What is the Strong Equivalence Principle?
This lesson will answer those questions. Useful tool: Units Conversion
Experiments by observer
This means that an observer cannot determine by experiment whether he or she is accelerating or in a gravitational field. In other words, results from experiments in an accelerating spaceship would be the same as those obtained from gravitation.
Experiment in accelerating spaceship
Note: One problem with this concept is that acceleration cannot be applied for too long a period, because the spaceship would soon reach the speed of light. On the other hand, gravitation is continuously present.
Einstein's conclusion
Einstein concluded that gravitation and motion through spacetime are related and that the Strong Equivalence Principle suggests that gravitation is geometrical by nature.
Difference between strong and weak
The difference between the Strong Principle of Equivalence and the Weak Principle of Equivalence is that the strong equivalence states all the laws of nature are the same in a uniform static gravitational field and the equivalent accelerated reference frame, while weak equivalence states all the laws of motion for freely falling particles are the same as in a reference frame that is not accelerated.
Summary
The Weak Equivalence Principle states that objects fall at the same rate, provided that are much smaller than the attracting body and are freely falling.
The equivalence of inertial and gravitational mass states that mass determined by inertia is the same as mass determined by gravitation.
The Strong Equivalence Principle extends the equivalence of masses to state that observations of acceleration cannot be distinguished from gravitation.
Physics is amazing
Resources and references
Websites
Equivalence Principle - Laboratory Tests of Gravitational Physics
Equivalence principle - Wikipedia
Elevator, rocket, and gravity: the equivalence principle - Einstein online
Books
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Top-rated books on Gravitation
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Strong Equivalence Principle of Gravitation