Yes. Gravity is stronger and quicker at smaller distances and slower and weaker at longer distances. Expansion is far slower than gravity. Expansion is like adding pieces of space distributed evenly in any given distance. This means that in twice the length of space away from us, one constant amount of space added is twice as much. This makes light that has a fixed speed require twice as much NEW SPACE (which is tiny between us and those near galaxies we can see as blue shifted. But the ones at great distances has that distance plus that distance times the new space added for light to travel through. But light that has already left, and remains constantly so, then has to stretch similar to two people with a fixed length jump rope who move away from each other make the any wave you can create stretched out. You can make, say, one large cycle loop the size of the distance between you. But if you add space between the two people on either side of the rope, the length of the same wavelength (loop-wise) is longer. Since wavelength is what we interpret as color. Anything thing that originally was created as a blue wave, which has a smaller wavelength becomes a different color. Blue is the shorter wavelength side of the spectrum and red the longer. So a 'red-shift' only means the the colors change TOWARDS one of those ends.Age wrote: ↑Fri Apr 26, 2019 10:05 amWhat do you mean by the 'degree of expansion is far less than'?Scott Mayers wrote: ↑Fri Apr 26, 2019 4:09 amThe degree of expansion is far less than that of gravity upon local stars or galaxies.Age wrote: ↑Thu Apr 25, 2019 6:15 am
But if some stars/galaxies are blueshift, then how does that then conclude that the Universe, Itself, is expanding?
If galaxies are moving closer to us, as you just said andromeda is, then some could say that that, combined with the other blueshift galaxies/stars, is evidence that the Universe, Itself, is NOT expanding.
If redshift is evidence for an expanding Universe, then what is evidenced by blueshift?
Do you mean that gravity upon local stars or galaxies is contracting faster than the 'degree of' expansion, which is supposedly happening away from the local stars or galaxies?
Or, some thing else?
If a car moving across your path at 100 miles per hour close up, you might see a blur as it passes you and notice its change. But if it is very far away, it would look like its not moving. This is like noticing the blue shift of closer stars and galaxies but it being very small at great distances.
Now, say that in one second one molecule of space is added between you and the distance of the road one foot in front of you as that the car drove by on. You wouldn't notice its effect for the amount being so tiny. But now add a million feet between you and some object. Then the amount of space added is one million molecules MORE space. Maybe only one million molecules may still be small, like say, the size of the point of a pin.
Now twice the million feet is two million feet away. That space has two million more molecules. If you know your math of exponents, you'd discover that though it is so small close up not to notice a red shift stretch of added distance per second is, there will come a point when the amount of space gets big very fast and then beats the appearance of any relatively tiny blue shift of something moving towards you.
This is where you would ONLY notice red shifts but then measure shorter general movements towards you as slightly less red shifted or those moving away as slightly more red shifted.
As just answered, you wouldn't see the actual colors change as MUCH, the farther away something is as you would closer, just like you can notice a car close up move say ten feet towards or away from you close up but not notice it if it were seen through a telescope where the cars are also moving the same ten feet in different ways. If you use a telescope and guess at how far ten a car moves ten feet when it is 10000 feet away is like being able to notice the difference between 10010 and 9990 feet. [that is 10000 plus or minus 10 feet.] The ten feet is still the same but if it is billions of light years away, you can't tell the actual difference.But what about the blue shift on the more distant galaxies? What do they demonstrate and/or what is interpreted on the blue shift of them?
This is what I find confusing here in this thread and in the other thread 'einstein on the train'.
Now, is 'red-shifting' evidence for the distance of galaxies compared to us, or, the evidence for the direction in which a galaxy is supposedly traveling, compared to us?
The 'evidence' for red-shifting is either for both of them or for one of them. If it is for one of them, which one is it?
What they CAN tell at those distances is the relative differences in tiny, tiny red shifts only. And most of this can only be noticed of galaxies where you can notice one side slightly red shifted and the other slightly blue shifted but still more red. The average distance to is the center of the galaxy and so the side more slightly slightly blue-shifted is the part moving towards us.
The relative left-right/up-down movements we see of closer galaxies. Like the spiral galaxies that have a center that is the average distance to us but you can tell which side on either side of the center is moving. When whole galaxies are moving closer due to gravity, they have a shift effect that point towards the center of the gravitational cluster. It would still appear only slight. But the overall galaxies as a whole are still redshifted.
Yes, to the first and second paragraphs. We can notice the shift of us relative to close galaxies to a greater extent than those of a billion light years away, just as the distance of 8 light-seconds is tiny compared to a galaxy 8 billion light years PLUS 8 tiny light-seconds change that far away.And that is exactly what I wanted to point out. The observed red-shift of distant galaxies might just be one side of the galaxy's spin, which is moving away, relative to us, AND, the blue-shift in those distant galaxies could just be the side of the galaxy which is moving towards us?
There is also the question of could the blue-shift and red-shift seen in distant galaxies be caused by how like the earth moves around the sun not in a perfect circle but sometimes in a towards direction and at other times in an away direction? (There is a word for this movement).
There are also other questions/explanations about what could be happening, which I have been waiting to ask but have just already somewhat answered/explained with your 'gravitational clumping' response, but I will leave them for another time anyway. (Memo for me relative time appearance).