Editing Principle of relativity (section)

==Basic concepts==
{{main|Galilean invariance|History of special relativity}}
Certain principles of relativity have been widely assumed in most scientific disciplines. One of the most widespread is the belief that any [[Physical law|law of nature]] should be the same at all times; and scientific investigations generally assume that laws of nature are the same regardless of the person measuring them. These sorts of principles have been incorporated into scientific inquiry at the most fundamental of levels.
<!-- I don't dispute the above, but a bit of elaboration is in order. Specifically, it seems counterintuitive to assert that laws of nature ''not'' being relative to the observer is an instance of relativity. -->

Any principle of relativity prescribes a [[symmetry]] in natural law: that is, the laws must look the same to one observer as they do to another. According to a theoretical result called [[Noether's theorem]], any such symmetry will also imply a [[Conservation law (physics)|conservation law]] alongside.<ref>{{cite book |title=Classical Mechanics: Hamiltonian and Lagrangian Formalism |first1=Alexei |last1=Deriglazov |publisher=Springer |year=2010 |isbn=978-3-642-14037-2 |page=111 |url=https://books.google.com/books?id=zEz5-HEu3D0C}} [https://books.google.com/books?id=zEz5-HEu3D0C&pg=PA111 Extract of page 111]</ref><ref>{{cite book |title=The Noether Theorems: Invariance and Conservation Laws in the Twentieth Century |first1=Bertram E.  |last1=Schwarzbach |first2=Yvette |last2=Kosmann-Schwarzbach  | author2-link = Yvette Kosmann-Schwarzbach |publisher=Springer |year=2010 |isbn=978-0-387-87868-3 |page=174 |url=https://books.google.com/books?id=e8F38Pu0YgEC}} [https://books.google.com/books?id=e8F38Pu0YgEC&pg=PA174 Extract of page 174]</ref> For example, if two observers at different times see the same laws, then a quantity called [[energy]] will be [[conservation of energy|conserved]]. In this light, relativity principles make testable predictions about how nature behaves.