Theophilosophical Physics: Ponderings on the Postulates of Special Relativity
Thinking about the relationship between physics, theology and philosophy gives me a headache, especially because physics is usually taught without a philosophical or theological background.
I'm currently attempting to learn modern physics better. However, I'm a tremendously lazy fellow. I need more than the usual prodding to do substantive reading, especially since I first encountered a lot of physics by school work. But this is my chosen field, and I do want to know it better. So I'm doing this the "fun way": I'll blog my progress and thoughts concerning what I'm learning, and I'm starting from Einstein's theory of relativity.
The postulates of special relativity are:
The laws of physics are the same in every inertial frame of reference.
The speed of light in vacuum is the same in all inertial frames of reference.
The first one seems simple enough, why would we call them "laws" if they simply changed with reference frame, it'd be impossible to properly calculate anything. It is an inertial reference frame because it is stationary with respect to the rest of the universe. There is no absolute frame of reference in relativity, which may seem like a very normal thing, but it pulled the rug from under the Newtonian's feet when it was proposed.
The "laws" of physics are generalizations based on observation of particular phenomena, but they require a (rather philosophical) belief that, at least in the overwhelming majority of cases, the inferences gotten from observation of one instance of a phenomenon will be the same when the phenomenon is observed anywhere in time and space.
The second postulate is what made special relativity an even more significant departure from the logic of Newtonian mechanics. To say that the speed of light is invariant (unchanging) in all inertial frames has some startling implications for physics.
It is this second postulate that leads to things like time dilation and length contraction. Because the speed of light is invariant, it is unsurpassable, infact it is quite impossible to even reach that exact speed if you're not a massless particle. It is "light" that carries "information" about an event, and it cannot move faster than 300,000 km/s.
One thing to notice here is that an object participates in causality when it is "influenced", i.e. when one of it's properties change, for example, momentum, speed, e.t.c. and the fastest something can be influenced by anything is the speed of light, as that is the fastest speed possible.
What this means is that the speed of light, denoted by c, is also the fastest speed of causality. To move faster than this speed means to break causality, hence why it is understood that to move faster than c is to move backward in time, which is regarded to be impossible.
My concluding questions would then be why should there be a speed limit on causality? And why this particular speed? And how does this affect me philosophically? or even theologically?
I am grateful to PBS Space-time for their very informative videos on the intricacies of physics, you can check them out here