> you can’t put space (which is a measurement of distance) and time (which is a measurement of, well, time) on the same footing without some way to convert one to the other.
This idea about 'equal footing' is really a hazy way of asking if these dimensions can be considered 'independent', which the article then describes as being interdependent.
> The key idea is that we’re all moving through the Universe, through both space and time, simultaneously. If we’re simply sitting here, stationary, and not moving through space at all, then we move through time at a very specific rate at which we’re all familiar: one second per second.
This second/second rate is 'c' the speed of light, but through the 'time' dimension of spacetime.
> However — and this is the key point — the faster you move through space, the slower you move through time. The other dimensions are not like this at all: your motion through the x dimension in space, for example, is completely independent of your motion through the y and z dimensions.
This point is misleading. These dimensions are like time in that if I was traveling at the speed 'c' in only the x direction, then to move in y or z directions, movement in the x direction would need to be reduced. The main difference is that we're observing these x, y, z motions in non-relativistic scales but since 1 sec/sec is already 'c', any observation of change in motion through time is relativistic.
> But your total motion through space, and this is relative to any other observer, determines your motion through time. The more you move through one (space or time), the less you move through the other.
Hopefully, now you can see that we're always moving at 'c' through spacetime. The only reason spatial dimensions seem qualitatively different is due to our observed motion through spacetime being timelike. A photon would have reversed qualitative characterizations of space vs time dimensions.
This video[0] (at ~1:55) illustrates this pretty well.
It's also worth mentioning that relative to us we are always moving through time with speed of c (there's no spacial speed). It's only relative to some other observers we are moving through space (and vice versa).
> you can’t put space (which is a measurement of distance) and time (which is a measurement of, well, time) on the same footing without some way to convert one to the other.
This idea about 'equal footing' is really a hazy way of asking if these dimensions can be considered 'independent', which the article then describes as being interdependent.
> The key idea is that we’re all moving through the Universe, through both space and time, simultaneously. If we’re simply sitting here, stationary, and not moving through space at all, then we move through time at a very specific rate at which we’re all familiar: one second per second.
This second/second rate is 'c' the speed of light, but through the 'time' dimension of spacetime.
> However — and this is the key point — the faster you move through space, the slower you move through time. The other dimensions are not like this at all: your motion through the x dimension in space, for example, is completely independent of your motion through the y and z dimensions.
This point is misleading. These dimensions are like time in that if I was traveling at the speed 'c' in only the x direction, then to move in y or z directions, movement in the x direction would need to be reduced. The main difference is that we're observing these x, y, z motions in non-relativistic scales but since 1 sec/sec is already 'c', any observation of change in motion through time is relativistic.
> But your total motion through space, and this is relative to any other observer, determines your motion through time. The more you move through one (space or time), the less you move through the other.
Hopefully, now you can see that we're always moving at 'c' through spacetime. The only reason spatial dimensions seem qualitatively different is due to our observed motion through spacetime being timelike. A photon would have reversed qualitative characterizations of space vs time dimensions.
This video[0] (at ~1:55) illustrates this pretty well.
[0] https://youtu.be/au0QJYISe4c?t=115