Variable speed of light in general relativity (3) might contradict Lorentz invariance (4) must modify Maxwell's equations (5) must be done consistently with respect to all other physical theories. Whether these concerns apply to the proposals of Einstein (1911) and Dicke (1957) is a matter of debate, though VSL cosmologies remain out of mainstream physics. Variable speed of light A variable speed of light (VSL) is a feature of a family of hypotheses stating that the speed of light in vacuum, usually denoted by "c", may in some way not be constant, e.g. varying in space or time, or depending on frequency. A variable
No symbol width, mass or speed. Per the European Agreement on the Vienna Convention, an oblique bar may not be used for any sign other than signs indicating no turning. An alternative use for red bordered circles is as a Mandatory Action Symbol type B. A green circle with no slash is sometimes used to mean that something is explicitly allowed, where it might otherwise assume to be prohibited, for example at an intersection where a U-turn is permitted. No symbol The international prohibition sign (official name), also known as a no symbol, no sign, circle-backslash symbol, nay, interdictory circle or universal