Editing Equivalence principle (section)

=== <span class="anchor" id="Weak"></span> Weak equivalence principle ===
<!--[[Universality of free fall]], [[weak equivalence principle]], and [[Galilean equivalence principle]] redirect here-->
The weak equivalence principle, also known as the universality of free fall or the Galilean equivalence principle can be stated in many ways. The strong equivalence principle, a generalization of the weak equivalence principle, includes astronomic bodies with gravitational self-binding energy.<ref name="WagnerSchalmminger">{{cite journal | last1 = Wagner | first1 = Todd A. | last2 = Schlamminger | first2 = Stephan | last3 = Gundlach | first3 = Jens H. | last4 = Adelberger | first4 = Eric G. | year = 2012 | title = Torsion-balance tests of the weak equivalence principle | journal = Classical and Quantum Gravity | volume = 29 | issue = 18| page = 184002 | doi = 10.1088/0264-9381/29/18/184002 | arxiv = 1207.2442 | bibcode = 2012CQGra..29r4002W | s2cid = 59141292 }}</ref>  Instead, the weak equivalence principle assumes falling bodies are self-bound by non-gravitational forces only (e.g. a stone). Either way:

* "All uncharged, freely falling test particles follow the same trajectories, once an initial position and velocity have been prescribed".<ref name=CliftonFerreiraPadilla/>{{rp|6}}
* "... in a uniform gravitational field all objects, regardless of their composition, fall with precisely the same acceleration." "The weak equivalence principle implicitly assumes that the falling objects are bound by non-gravitational forces."<ref name=WagnerSchalmminger/>
* "... in a gravitational field the acceleration of a test particle is independent of its properties, including its rest mass."<ref name="Wesson">{{cite book |title=Five-dimensional Physics |first=Paul S. |last=Wesson |page=82 |url=https://books.google.com/books?id=dSv8ksxHR0oC&q=intitle:Five+intitle:Dimensional+intitle:Physics |isbn=978-981-256-661-4 |publisher=World Scientific |year=2006 }}</ref>
* Mass (measured with a balance) and weight (measured with a scale) are locally in identical ratio for all bodies (the opening page to Newton's ''[[Philosophiæ Naturalis Principia Mathematica]]'', 1687).

Uniformity of the gravitational field eliminates measurable tidal forces originating from a radial divergent gravitational field (e.g., the Earth) upon finite sized physical bodies.