Okay so I know that this has been a prompt several times before on this sub, and this post is me giving one final shot at attempting to understand the intricacies.
My brain, due to lack of prerequisite/foundational knowledge or perhaps sheer stupidity, simply cannot comprehend the fact that a clock on Earth will tick faster than, say, a clock on Voyager II. I have two main questions, likely only surface level following your guys’ explanations:
1. What exactly is spacetime, and how do gravity and speed warp it? I’ve heard the ‘trampoline’ theory of time where objects with mass create a dip in spacetime that other objects of lesser mass ‘fall’ into. I’ve seen the visual, and I feel as though I’m missing something fundamental that explains exactly what it means to warp/create a dip in this ‘plane’ of space. How does that affect time?
2. What do you mean, “The speed of light is constant”? If you’re in a spaceship, hurtling through space at 50% the speed of light wouldn’t the light coming at you from the front of the spaceship be 50% faster than usual to you, and the light at the tail of the spaceship be 50% slower for you? And how the hell does this make it so you age slower than your twin brother on Earth? Why was one hour on planet Miller seven years on Earth in Interstellar? Help???
I don’t want to be stupid; being stupid really is my biggest fear in the universe. But how can I possibly wrap my brain around the concept of time, pretty much the only constant I thought there was in life, being not-so constant?
In: Physics
1. Basically what it sounds like, all three spacial dimensions + time, represented just like another spacial dimension. These sorts of constructs are primarily *mathematical* models, but they happen to be *really* useful in describing reality, even to the point of predicting behaviour that we haven’t actually seen yet – this is how we discovered the black hole. When we treat time like another spacial dimension, it turns out to be a really useful way of thinking about the universe, so thats as good a reason as any to say that’s how it actually is.
If you’re having trouble simply *visualizing* “curved space”, check out [hyperbolica](https://youtu.be/yY9GAyJtuJ0?si=cuWGfHwIi1ZjWfUy), a game that is designed to give you an idea of what curved space is like. Mass and gravity curve spacetime because that’s what mass and gravity *are*.
2. No. That’s the whole thing! The speed of light is always moving at the speed of light *relative to the observer*. Weird right? Check out Einstein’s thought experiments to get some insight as to how/why time and length dilation are natural effects of a constant speed of light.
As a sidenote – the “speed of light” may make it seem like light is special, but actually its more like a “speed of causality”, and light (in a vacuum) moves as fast as possible.
There’s better explanations out there but if you have any Qs i can try
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