Hijack from greater than c expansion

[Dekan]

There's no such thing as "Space"! It's just a synonym for "Separation" or "Gap".

 

So when earnest scientific posters keep talking about "the expansion of Space" - they could just as well be talking about "the expansion of Gap"

 

Isn't it disappointing to see how easily language stops clear thinking?

[swansont]

OK, let's play the semantics game. The gap is expanding, but locally nothing is moving particularly fast and certainly not above c. i.e. the gap is expanding but not because of the motion of the objects. Does that really change anything from a language perspective? Or a science perspective?

[Strange]

It is not clear how your wording is significantly different than the usual one. The main reason that "expansion of space" is used as the description/analogy is because the metric (the way distances between events) is defined is in terms of space-time. Of course, you could write a description of relativity and cosmology using "gap" instead of space/distance (e.g. "1 AU is the gap between the Earth and the Sun"; "the relation between the recessional speed of galaxies and the gap between us and them is called Hubbles law"). But I'm not sure what the point is.

 

Do you want to change "time" to something else as well? Perhaps "tick"; then we can say, "relativity models the universe as a four-dimensional gap-tick manifold."

 

There are some people (typically those with unscientific "personal theories") who try and argue that "space" is some sort of material substance rather than just part of the geometry of the universe. It sounds as if you are on the right side of that particular bit of silliness. So, I am not sure what you are objecting to.

[Dekan]

Swansont & Strange, I'm objecting to the word "Space".

 

This word could be replaced by "Gap", and if it was, we might see that the whole argument is an artefact of language.

 

As Strange points out in #3, we could replace "Time" by "tick", and then debate the nature of "Tick".

 

Just as we could debate the nature of "Gap".

 

Changing "Gap" into "Space", and "Tick" into "Time", doesn't change anything, except to make the words sound more abstruse.

[swansont]

Swansont & Strange, I'm objecting to the word "Space".

 

This word could be replaced by "Gap", and if it was, we might see that the whole argument is an artefact of language.

 

As Strange points out in #3, we could replace "Time" by "tick", and then debate the nature of "Tick".

 

Just as we could debate the nature of "Gap".

 

Changing "Gap" into "Space", and "Tick" into "Time", doesn't change anything, except to make the words sound more abstruse.

 

There's more to it than the gap becoming larger, because nominally the objects aren't moving, as measured locally. Space-time has a particular definition within physics, which is not identical to that of a gap. Similarly, conflating a tick with time leads to conceptual errors, because a clock that ticks fast may do so because of a mechanical effect instead of a change in time itself.

 

However, if it's true that the words are interchangeable, then what does it matter what you call it?

 

Lay language is generally much less precise than scientific language (and that less precise than equations). One need look no further than how the word theory is bandied about to see this.