Tired Light

Tired light is also ruled out by Millisecond Pulsars (MP hereafter). These stars are extrememly dense. They also rotate at fantastic speed. In fact, this is how they got their name. Because we know the mass of these stars and their speed of rotation, we also know that if they were going any faster they would be torn apart by centrifugal force. If light were slowing down (ie Tired Light) this would mean that we are actually watching a slow motion replay of these MPs, an impossibility as stated above. These MPs can not spin any faster than what we observe meaning that Tired Light is also an impossibility.