Member Rara Avis
Yea, for the last 2,000 plus years, the correct answer was to add the two velocities and arrive at 200 mph. And, yea, you're right again, relativity changed that. It had to change it. There is nothing preventing that train from going "almost" the speed of light. Say, C -50 mph? If you threw your fastball off the back of the train, then, the ball would be travelling C + 30. That's a bit of problem since nothing can exceed C.
Our instincts and common sense tells us to just add the velocities, giving us the formula t + b (train plus ball). This worked for several thousand years. When a particle travelling at high speeds emits another particle, however, that formula falls flat on its face. The math isn't real important, but here's the correct formula for adding velocities.
v = (t + b)/(1 + tb/C^2)
At the kinds of speeds we travel here on Earth, the difference between those two formulas is impossible to even measure. A space craft orbiting our planet at thousands of miles per hours can still use the old t+b formula, too, because at those "human" speeds, it really doesn't matter. Only when we observe particles travelling at a good fraction of the speed of light in particle accelerators do we discover, lo and behold, Einstein was right yet again.
Okay, so what does all this have to do with causality?
The principal of cause and effect is just as ingrained into our "common sense" and experience as was the adding of velocities. It's hard for us to imagine that travelling faster and faster will actually cause our mass to increase and time to slow, because its something we haven't (and likely never will) actually experience or see. Only when you get outside the realm of human experience does it hold true. In a similar manner, it's hard for us to imagine an effect without a cause. In our human experience, everything was caused by something. But relativity and quantum mechanics dramatically demonstrate that our human experience is limited. There's a whole lot going on in the universe that we never see.
I think causality is almost certainly a localized phenomenon. Heisenberg's Uncertainty Principle, for example, shows us that a particle can go from point A to point C without ever passing through point B. And it does so for no reason beyond the fact that it can. You'll never be able to point to a specific particle and say, "It's going to tunnel from A to C because ..."
Maybe we just don't know enough yet to determine cause? Maybe. But I suspect that as science advances, we're only going to discover more and more areas where cause doesn't necessarily precede effect. If Einstein's citadel should ever be toppled, for example, and the speed of light is no longer considered a universal limitation, everything we think we know will be turned upside-down. Time can be made to run in any direction you want, and cause and effect will become effect and cause, with the waters muddied beyond any possible clarity.
Who created God? I think we're in agreement that God is an exception to the rule of causality. But the minute you allow one exception to creep into your reality, a few more are always just around the corner. Somehow, I don't think that's unintentional.