http://www.theflatearthsociety.org/forum/index.php?topic=54119.40#.VmpxAdJ961shttp://www.theflatearthsociety.org/forum/index.php?topic=54119.msg1333450#msg1333450http://www.theflatearthsociety.org/forum/index.php?topic=30499.msg1480194#msg1480194
If we are not speculating then we must assume
even if the speed of light is variable (which i highly doubt)