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Comment by cpleppert | Hacker News Reader

That doesn't make sense at all. The whole point of cosmological expansion is to explain relations between redshift and distance. That is what was suggested to Hubble back in the 1920's when he plotted this relationship. If you don't hypothesize any global relationship between these two values then every galaxy just happens to have a larger velocity depending on distance. The link doesn't explain why this would happen.

I'm a little concerned about some of the other stated problems that the 'theory' tries to solve. For instance,

>>They believe that sufficiently large objects stretch or break apart, and proffer explanations as to why smaller objects, like galaxies, don’t do likewise.

Spacetime isn't an object! I think gravity is a great explanation why galaxies don't break apart..

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> The link doesn't explain why this would happen.

Physics doesn't answer why on anything. Hubble's observations still apply. He didn't try to explain why the observational data is what it is.

> Spacetime isn't an object!

Where was the opposite claimed? I don't see it.

> I think gravity is a great explanation why galaxies don't break apart..

That's fine, but you still have a flatness problem that also needs an explanation. If you don't need your explanation (by obviating the expanding space paradigm) the flatness problem vanishes.

You can edit my response and change the 'why' to 'how.' Doesn't matter. The author still posits no mechanism for why the distribution that Hubble observed holds for every galaxy in the sky nor does he ever address this point at all. He doesn't say it isn't relevant or can be explained in a simpler way he just ignores the evidence.

So given a proposed explanation that explains observed phenomena the author claims nothing at all except that it would be consistent (if you get rid of the observed phenomena) to not have the theory. That is a nonsensical argument that begs the question.

I.e. if gravity didn't exist apples would still be red Q.E.D. gravity is unnecessary

> Where was the opposite claimed? I don't see it.

He wants to say that because galaxies don't break apart but the universe does somehow there is an arbitrary limit on the size of objects that 'break apart.'(Do you think some other object other than the universe if being referred to here? What is breaking apart that is larger than galaxies and would remotely make sense here?)

This is rather strange because gravity(and the atomic forces) are far stronger than cosmological expansion so his 'point' doesn't make sense.

> The author still posits no mechanism for why the distribution that Hubble observed holds for every galaxy in the sky nor does he ever address this point at all.

Hubble found that the galaxies are moving apart from one another in the simplest possible way they could do that. (If they weren't moving apart from one another they'd be moving toward one another, or some mixture.) No further explanation is needed unless one thinks that movement violates some other tenet of physics, like the cosmological principle or Einstein's speed of light limit; in that case you need an additional explanation like the expanding space paradigm so you can save the other tenet(s).

Also note that the expanding space paradigm just shifts the why / how question to some other chapter of physics. What is the mechanism that expands space itself? Nobody has that answer.

> He wants to say that because galaxies don't break apart...

Not he/she, not the author. What you quoted was about what cosmologists generally accept today. Cosmologists generally accept that there is some limit on the size of objects that break apart due to space itself expanding. Below that limit, gravity and the atomic forces keep the object from breaking apart, they believe.

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