Editing Special relativity (section)

=== Relativity without the second postulate ===
From the principle of relativity alone without assuming the constancy of the speed of light (i.e., using the isotropy of space and the symmetry implied by the principle of special relativity) [[Derivations of the Lorentz transformations#From group postulates|it can be shown]] that the spacetime transformations between inertial frames are either Euclidean, Galilean, or Lorentzian. In the Lorentzian case, one can then obtain relativistic interval conservation and a certain finite limiting speed. Experiments suggest that this speed is the speed of light in vacuum.<ref name=Friedman group=p>{{cite book|author=Yaakov Friedman|title=Physical Applications of Homogeneous Balls|series=Progress in Mathematical Physics|volume=40|date=2004|pages=1–21|isbn=978-0-8176-3339-4}}</ref><ref name=Morin2007>David Morin (2007) ''Introduction to Classical Mechanics'', Cambridge University Press, Cambridge, chapter 11, Appendix I, {{isbn|1-139-46837-5}}.</ref>