Tlaloc_Temporal

Actually that's a good point about interferometers, the only detectable change whould be in the difference between each arm's length.

Gravitational waves do behave like EM waves, we've seen a neutron star merger simultaneously in gravity and light. If there was a difference, one observation would lag behind.

How exactly would we measure an absolute value of distance? The whole thing about general relativity is than everything is relative. If everything was scaled up such that the fine structure constant stayed the same, we wouldn't be able to measure a difference.

Which brings us back to the question I have with your model: How can a changing distance be measured by light to be the same (metre bar) but also different (redshift)? If light is scaling with the rest of the universe, it shouldn't get shifted. This in the crux of my confusion.

And yet you said that a metre bar would be larger yet measure the same. If all the aspects of the universe are expanding in lockstep such that any distance appears constant, then redshift caused by expansion is impossible.

If the increasing distance between atoms is unmeasurable, then so too must be the increasing distance between galaxies be undetectable.

LIGO can detect changes of distance on the order of 10⁻²¹, and it should be increasing in effective length by 2×10⁻¹²m/s, yet I don't see any mention of any large interferometer measuring anything but gravitational waves, and I don't see any large time-dependent components of LIGOs systemic error data.

We also can measure the increasing distance of galaxies via redshift, so unless you can explain how light from galaxies is different from the light in a large interferometer, I must conclude that the interferometers aren't expanding at the same rate as the observed expansion of the universe.

We aren't expanding like the universe is expanding.

Yes, relatively means that light appears to move at c in every inertial reference frame. That doesn't change how we measure distance in a single reference frame.

How can a metre bar be measured as a metre when it's one unit and two units long? We're measuring the bar in it's own reference frame each time, so relatively causes no change. Either c increased, or time slowed down to match the expansion of space. Either way, light doesn't get redshifted by expansion.

Help me understand, how does light appear to change speed over time in the same reference frame? How do we see a change of distance affect light between galaxies, but not between atoms?

I am aware of what redshift is. What I don't understand is how you think a metre bar can expand and the speed of light increase in lockstep with it such than we can't measure the change.

Let's say we have a metre bar that's currently one unit long, and we measure it to be one metre long. There's also a galaxy a billion light years away.

Let's say the universe doubles in size after a billion years. The metre bar is two units long, but we still measure it to be one metre long, because the speed of light has doubled (presumably). We measure the light as the same length. The light from the galaxy has now reached us, and is twice as long, but is also moving twice as fast, so the wavelength stays the same. We measure the light as the same length.

Do you see my issue with this situation? How can the measured length of light change (redshift) while the measured length of light also stay the same (metre bar)?

Either redshift isn't caused by expansion, the fundamental forces and constants are changing as we expand, or space is expanding but matter isn't. We have good corroborating evidence that redshift is caused primarily by expansion. We also have evidence that the laws of physics haven't changed significantly in at least the last 2 billion years or across the universe. And lastly, we can measure the acceleration of expansion by several corroborating methods, including redshift.

I'd love to be proven wrong here, the implications of gluons being streched by expansion is fascinating.

What is expanding in this scenario? If atoms are expanding, then either atomic forces have also scaled to match the expansion, or atoms are getting more radioactive?

I don't understand how atoms are supposed to be expanding in this model. The size of atomic nuclei and electron clouds are governed by the strength and range of the fundamental forces. If everything was expanding in lockstep such that atoms expand but don't change their properties, then there would be no observable effects. Yet we can see the distance between galaxies not just getting larger, but speeding up.

If orbits, matter, and even the fundamental forces were expanding to match, no such change in "distance" should be possible, beyond the normal movement of matter.

If our metre stick was measured as 1/299,792,458th of a light second, then a million years later it was measured as exactly the same length but was somehow dimensionally larger, then lightseconds must have become larger is lockstep.

If that were true, this expansion could not explain the redshifting of light, as c would increase in lockstep with space, leaving light the same wavelength. Redshifting only happens when the distance between waves increases in relation to the speed of light, and so a universe with redshifting must have a difference in the rate of expansion and the rate of c scaling. Such a difference should be visible as increasing distance or an increase in the flow of time, at minimum.

In your model, everything is expanding equally. Literally everything, including the speed of light, the elementary charge, and even the plank constant, are expanding in lockstep, to the point of unobservability. Is this right?

Yes, all distances are expanding, but not everything in space is expanding. Atoms aren't expanding because atomic forces are far stronger than expansion is, for example.

Yet the distance between galaxies is increasing, so there must be a crossover point where one structure can stay structured but a slightly bigger structure is torn apart.

My question was if this size is larger or smaller than galaxies, and it seems to be quite a bit larger than galaxies at the moment.

The interesting thing is that the expansion is increasing, so this size limit is shrinking. Unless some change in forses happens (like inflation or some kind of false vacuum collapse) the limit will eventually be smaller than galaxies and they'll get ripped apart. Eventually star systems will be ripped apart too, then stars (if any remain at that point) then planets, molecules, atoms, and bosons; and if if that continues to quarks funny things start happening that kind of look like the big bang.

That last part is still speculation of course, but I do still wonder if the expansion of the universe affects galaxy formation and dynamics, and if ancient galaxies were different in part because of this.

That wouldn't significantly affect most galaxies though, would it? The rasin bread model might insinuate that the space in a galaxy isn't expanding (which is wrong), but it is accurate in thst gslaxies themselves are not growing larger.

At the planetary scale, such a change would be completely overpowered by other orbit defining effects, like resonance, mass flow/loss, and even drag.

At the cluster scale, I can absolutely see spacetime expansion overpowering gravity.

At the galaxy level, I can't tell. Does spacetime expansion limit the size of galaxies? Is that limit shrinking due to the acceleration of expansion? Are galaxies under that limit larger than otherwise expected? Is this effect large enough to effect the speed of galaxy rotation and does it need to be taken into accout when measuring the effects of dark matter?

Are you sure that galaxies are growing? They're gravitationally bound enough to have organized orbits, do those orbits get larger over time?

Algae and plankton. It also obviously takes longer than a few minutes, like at least an hour.

Reminds me of tumbleweeds, which may as well be a Soviet bioweapon.

I think that would make coal. Oil is made by algal anr plankton blooms, which we are also making.

Both also need heat, pressure, and time to form, so synthetic carbon products are certainly chearper.