wholookshere

Chrome was started by google

You are correct that the raisins would have other constraints to keep it from infitatly expanding into nothing. Not because it's not expanding but because it has external constraints like gravity keeping it there.

They do have expansion applied to them, but gravity and other things effecting space time would be keeping it on place.

As for attoms, I think you picture something solid. But there's not. The electrons are getting further from the nucleas, but it's still bound quantum mechanically to the attoms regardless of its position.

But then the nucleas isn't soldi either. It's made of smaller things yet, and so on and so forth. So inside would also be expanding. But again other forces at play would bind things together.

The expansion is also not a force. It can't overcome other forces so it keeps things in line.

So it does happen on a small local scale though. It happens on ALL scales.

But everything is expanding from everything. Meaning the observer is always centred of the expansion. This is because volume is constant. The rasins themselves do expand, but locally it's such a small scale (10^-23 m/s for our solar system).

This also works for how we understand the change in density. Volume is constant, but we've gone from infinitely dense to almost nothing.

I think the trouble is also partly based around thinking of then universe as a volume, which implies a centre. And that's where this analogy falls apart.

Because everything is expanding from everything, there is no centre. YOU are always centre. So you are "expanding" but you don't change volume.

This is why I keep saying space isn't getting bigger, distance is.

It's not that a sheet of paper becoming bigger so the grid paper becomes larger,. It's changing it's distance of something, not it's size and shape.

We don't observe galaxies getting bigger. We observe them constantly moving away from us. Even. When they're moving to us, but it's done at a slower pace than expected. The further away you are, the faster you move away. And it's a universal constant of 73km/s/Mpsc.

Notice that is a speed per distance. It's not saying space is getting bigger, it's saying things are moving faster away from you the further you go away.

The universe isn't expanding like a loaf of bread because it has a volume. It's expanding from one volume to another. Where the universe doesn't.

The answer is there's no such thing as absolute distance. Because there's no such thing as absolute position. Quantum garuntees inaccuracies in position.

And your right. We can't actually measure the expansion of the universe directly. It's actually because of the red shift we do.

The reason we can see the red shift is because the universe holds the speed of light in a vacuum constant.

So if the universe is expanding, and the speed of light is expanding with it, in-order for the speed of light to stay the same, it has to travel more distance in a time. Meaning it's stretching it's wavelength as it moves. Just like something moving away from us does. IIRC it's because of observations that everything is constantly moving further from us, the further out you go, the faster it's moving away.

But everything is moving from everything, including itself.

I do apologize if I'm a little muddy, I did my physics degree about a decade ago.

Edit as for why gravitational waves travel at the same as E&M waves is because "information" is what travels at the speed of light. For an electro magnetic wave that's disturbances in E&M. For gravity that's ripples in the fabric of space-time. For quantum there's experiments showing that entangled particles will collapse together, if sperated by distance, the lag time is also the speed of light.

EDIT 2:

The only thing faster than the speed of light, is actually the expansion of the universe beyond a certain distance. Don't remember what it is. But because distance istself is expanding, that's proportional to distance. So the expansion rate is actually faster than the speed of light far enough out. But no SINGLE point is expanding faster than the speed of light.

We can still measure the red/blue shift to find the star, but if you don't correct for it, it will be wrong.

Also I don't know enough about gravitational waves wo know how it would be effected by the expansion of the universe.

But remember when LIGO measures, it's not measuring absolute values that we would see drift in. It's all relative measurements from a short time period prior. It would follow in lockstep with the expansion.

Also gravitational waves arent particles. They're disturbances in the fabric of the universe. So they don't behave like standard waves do. They have their own wave mechanics that I haven't studied.

And light is having its wavelength stretched. Speed of is not proportional to frequency in a vacuum only the permittivity and permeability of free space. So it's wavelength is getting expanded without

But again. Space isn't expanding. Distance is.

Also that's not how informeters work.

They compare distance across two lines. They can only detect the differences between those lines. Because expansion is universal in all directions, it's not detectable on informeters.

The reason the speed of light doesn change is because rthe universe bends the rules of time to make it the same. So as the universe expands, the speed of light stays the same because the definition of time changes.

Like I said. The expansion of the universe isn't space expanding, it's the definition of distance that's expanding. Yes time is being fucked with as part of the expansion. But the universe doesn't hold distance or time as constant frames to compare to. As speed is only calculated with a frame of reference. Where distance is a little more fundamental to the universe.

Because the scale is so so much less. Like 73 km/s/Mpc.

So the rate of something to the scale of 10^-9m, would be somewhere in the order of 10^-25m/s. Which is much much smaller than anything with the attoms itself.

But the distance is always the same. A meter is still a meter in all points of time. But it's still bigger.

So you assume the speed of light is the same between references frames. There not. It's always the same. The definition of a second changes such that the speed of light is always the same.

That's relativity.

Yes everything is expanding like that.

Look back to the red shifted light.

When a white star starts with white light, has the literal wavelength expanded to be more red looking.

https://www.esa.int/Science_Exploration/Space_Science/What_is_red_shift

It's the literal light getting shifted. So the speed of light is the same, but the distance it travels in a given time is not. Making it red shifted.

So yes attoms are expanding. everything is expanding. I mean that very literally.

Let me put it this way.

If you had a million year old meter stick. It would always be a meter. Accurate to the definition of a meter using the wavelength of I don't remember what off the top of my head. It would always be a meter exactly.

But.

If you magically placed the meter stick next to itself from a million years ago, they would not measure the same. Even though they started with the same definition.

Like I said. Space isn't expanding. Distance is.

EDIT I don't mean the distance between things is expanding. The definition of what a distance was is expanding. So yes, attoms, when measured by size (the distance from one edge to another) has also expanded.

But in the same breath, the measured distance never changes. Because the way you use to measure distance has also expanded by the same amount. So nothing ever changes in reality, but everything is just constantly bigger.

Physics is full of hard to explain paradoxes.

I see where this is diverging a little bit.

But everything is expanding. Including matter. But the mass isn't chaning.

But this also includes the space in between the objects.

So objects are getting further apart, but so are the objects getting bigger at the same rate.

The mind bend for me was realsing it's not space that expanding really, it's distance.

This is why distant light is red shifted. Because what started out as white, has had the wavelength expand with the universe, making it appear more red.

We're estimating once a decade. Not thousands a day.

Could the estimates be wildly off? Yes. But that's still pretty wild conjecture lol.