Does space-time describe the relationship between different frames of reference?

[geordief]

I hear that a body is supposed to travel through space-time at the space-time "speed" of c.**

Hope I have heard and reported that correctly.

If that is so ,it seems to me it may be a mistake to imagine that body as "voyaging" through space-time in a manner akin to Voyager as it travels out through the the solar system and on into intergalactic space.

Would I be right to view this space-time traveling as simply describing the way 2 frames of reference calculate the way the other  travels/moves wrt its own frame of reference?

Does this idea of a body traveling through spacetime at c suggest (wrongly) that that body is somehow traveling through some kind of a space-time ether (or at least something of an absolute nature)?

**ie even if the body is standing still ,it is judged to be moving through time at c.

 

Edited November 11, 2020 by geordief

[swansont]

There is no ether. There is no absolute frame

Spacetime is not a substance. It’s space + time. It represents the four dimensions.

In your own frame you are at rest, so you travel through time at the maximum rate, c.

If measured from another frame, you are moving at some speed v, and your rate through time is dilated. The four-velocity is always c.

[geordief]

31 minutes ago, swansont said:

There is no ether. There is no absolute frame

Spacetime is not a substance. It’s space + time. It represents the four dimensions.

In your own frame you are at rest, so you travel through time at the maximum rate, c.

If measured from another frame, you are moving at some speed v, and your rate through time is dilated. The four-velocity is always c.

To be in one's own frame implies the existence of another frame ,doesn't it?

 

An isolated frame is an idealization (?)

 

This is all about relationships between frames ,isn't it? 

[swansont]

46 minutes ago, geordief said:

To be in one's own frame implies the existence of another frame ,doesn't it?

No, in general. There are problems that only require one frame. No need to use another frame.

But in relativity you often need to incorporate multiple frames.

 

46 minutes ago, geordief said:

An isolated frame is an idealization (?)

I didn’t say anything about an isolated frame 

46 minutes ago, geordief said:

This is all about relationships between frames ,isn't it? 

SR is.

[geordief]

35 minutes ago, swansont said:

No, in general. There are problems that only require one frame. No need to use another frame.

Wouldn't just using one frame imply nothing was in motion?

[swansont]

16 minutes ago, geordief said:

Wouldn't just using one frame imply nothing was in motion?

No, it means you’re not doing any analysis from the perspective of any moving objects. No transforms involved. Which is most of Newtonian physics, where relative time isn’t a thing, so there’s no point in bringing in another frame.