Quoth filmore:
Yup. Time as a dimension does have some subtle differences from the three spatial dimensions, but fundamentally, it’s mostly the same thing.
I would like an answer to this too, since at first glance - as far as I know - it seems to be true, but the fact that speed is relative makes it hard for me grasp. This may be because I don’t fully get special relativity, let alone general relativity.
To expand a bit:
I can sort of get at the idea that a non-moving (in space) object would move at C in time. The idea seems to be that you’re always moving at C, but there are 4 dimensions of movement, so if you’re moving faster in space at some “speed”, you’re also moving slower in time. My first question is “what does it mean to move slower in time?”. Is it just a direction? If so, why do we move at all?
First of all, don’t worry about speeds being relative. That’s only true for speeds other than c, but c itself is not relative: c is c, regardless of reference frame.
Second, yes, you’re correct that everything is always moving at c, and it’s just that most things are usually mostly moving in the t direction. Moving slower in the t direction means that your clock will run slower than one that isn’t moving (at least, in the reference frame of that other clock).
I don’t know the reason but I guess it has to do with the permittivity and permeability of space. I haven’t seen a good explanation for why inertial mass is what it is either.
Maybe we just need to accept the fact that not everything has a reason or a “why” to it. Because if everything really had an explanation or a cause for why it is what it is than we would get an infinite regress of “whys” and that is paradoxical. Some things just are and there is no reason why they are what they are. There doesn’t have to be a cause for everything.
Of course you could say that God or some ultimate reality is the answer for everything just because we don’t know the true answer but someone could ask the ‘why’ question again like why is God the answer or why is there a God instead of no God.
Cause-and-effect is a powerful tool but it does have its limits.
I often think that c being popularly known as “the speed of light” does us a disservice, because it implies that light is somehow special and defines c, not the other way round. Light moves at c simply because that’s the fastest anything can move.
Yeah, I know, stupid obvious comment. More a comment on conversations I’ve had rather than anything anyone here on SDMB has said.
For the record, it’s considered bad form around here to resurrect an 8 month old thread in General Questions without actually providing a factual answer relevant to the discussion.
Some folks use the label “Einstein’s constant” for c, instead of calling it “the Speed of Light”, for this reason. It doesn’t really seem to be catching on, though.
I don’t think that’s stupid or obvious at all, and is well made in your post. I think most people think precisely that: the speed of light defines the fastest the universe will allow, instead of the [correct] reverse: the fastest the universe will allow is the speed that light then travels at.
Which I wonder may be a solution to the LHC FLT issue: c is actually faster that the speed of light is generally measured at. That is, we have measured the speed of light in a vacuum many times and have assigned that value to c, whereas true c is somewhat faster than that, and light can never quite travel at c due to some unsuspected factor (such as the quantum foam slowing it down by the tiniest fraction).
As of now, we consider it a constant and we don’t know why it has that value.
There are too many other universal quantities that depend on c or have their seemingly unrelated constant value too, that we can’t explain why.
Multi-universe theorists propose that c may have a different value in other universes - if they exist.