Atheism

Religion aside, the topic about the speed of light is actually really fascinating, actually. I didn't quite grok what it was all about until recently watching a particular video which I'll link at the end.

The going theory (and here theory means our best model for how a thing works) is that the speed of light is constant in a vacuum. You may be familiar with the toss-a-ball-on-a-train (🚂) thought experiment?

If I'm traveling on a train traveling forwaes at 20mph and standing still relative to the car I'm in, and toss a ball at 10mph in the direction of the train's travel (toward the front), an observer outside the train could see and measure the speed of the ball they would find it is traveling 30mph relative to the ground (20+10) in the direction of the train's motion.

If I had thrown the ball in the opposite direction, toward the back of the train, the ball would be traveling at 10mph towards the front of the train (20-10)

Speed is measured relative to a frame of reference, ground or train, say.

Now if I were to instead use a flashlight, how fast would the photons travel if I were pointing the flashlight towards the front? The back? (And let's assume everything is in a vacuum to illustrate the point)

They wouldn't be 20mph + c forward or c - 20mph toward the back. The photons would travel at c.

Experiments have proven that c is constant-- that photons don't go faster when being emitted from a source already traveling at a given speed (see: Michaelson-Morley experiment among others). (A number of experiments demonstrate the general theory of relativity holds up at large scale, too).

But anyway, how can light possibly be constant regardless of the motion of the emitter?? It's a paradox right? It is because spacetime isn't "constant". That's where the video comes in...

https://youtu.be/Rh0pYtQG5wI?si=d1FG5jpGi6cghY5t

It may be more accurate to think of the process of science as: developing, verifying, and updating models based on the results of high quality evidence gathered from experiments that follow the scientific method.

That is to say that if sufficient, good evidence is gathered contradicts a model, the model is wrong, at least for the specific conditions of the experiments in question. In that case the part of the model addressing those conditions has to be updated. (In some cases the conditions are "all" essentially and so the whole model has to be tossed...like the aether theory).