2)
beside the Doppler effect, there is a correlation between dimness and apparent size of the galaxies we see. Hubble Space Telescope can see amazingly faint galaxies and in the pictures they are tiny compared to the bright nearby ones.
And the nearby ones can have their distance measured by techniques not involving Doppler shifts of their light. So, whenever a new telescope reveals more fainter and tinier looking galaxies, a very simple explanation is they are further away than the ones that are brighter and appear larger.
Astonishingly faint galaxies are astonishingly far away.
And just observing a Doppler shift in a galaxy's light isn't the only thing Dopler can do for us. If a star explodes and we note the side of the debris cloud facing us is approaching us at 10% of the speed of light, then we know that perpendicular to a line to us, the debris is also expanding at 10% + 10% (for each side) the speed of light, so if we look again in 10 years and see the debris cloud looks bigger, simple geometry can give a surprisingly accurate distance.
for example:
If I am watching a kid blow up a balloon miles away thru a telescope, and make a rough estimate of how fast kids can blow up balloons, knowing the magnification of the telescope and how big the balloon appears to be getting, I can figure out (if I were younger and remembered high school geometry better) how far away the kid is.
If I just assume all balloons are the eventually the same size, I can figure how far away all the balloons I can see are.
Technique would be similar for cars instead of balloons, stars instead of cars, galaxies instead of stars. If I figure out there are different kinds of stars then I can be more accurate if I figure out what kind of star I'm looking at, same for galaxies, the more I know the more I can find out.
The spectrum of distant galaxies also show absorptions at different Doppler shifts from gas clouds between here and there. And the further out we think we are looking, how about that, more lines of absorption appear because there are more gas clouds along the way.
It all hangs together. We don't see stars that are Cepheid variables in galaxies shown to be too far away for us to see them. So, things we don't see also help. As telescopes improve, we can see Cepheid variables further and further out, lo and behold, they are are consistently distant with the distances already worked out via other means. So stuff we didn't see because it was too far/too faint at one time, that later becomes visible with better equipment helps establish confidence in what was worked out before with lesser equipment.
At some point (I believe the estimate is 30-40 years) we should have equipment to directly detect changes in the Doppler shifts of extremely distant objects that are caused by a possible acceleration affect, or rule out that theory if a decel is detected.
Unlike religion, cosmology doesn't need special pleading, reliance on 'belief', or preconceived dogma to work out things. Someone comes up with an idea, develops an observation strategy to confirm/deny the idea, gets a confirmation observation(s) from somebody else, and you've got something.
beside the Doppler effect, there is a correlation between dimness and apparent size of the galaxies we see. Hubble Space Telescope can see amazingly faint galaxies and in the pictures they are tiny compared to the bright nearby ones.
And the nearby ones can have their distance measured by techniques not involving Doppler shifts of their light. So, whenever a new telescope reveals more fainter and tinier looking galaxies, a very simple explanation is they are further away than the ones that are brighter and appear larger.
Astonishingly faint galaxies are astonishingly far away.
And just observing a Doppler shift in a galaxy's light isn't the only thing Dopler can do for us. If a star explodes and we note the side of the debris cloud facing us is approaching us at 10% of the speed of light, then we know that perpendicular to a line to us, the debris is also expanding at 10% + 10% (for each side) the speed of light, so if we look again in 10 years and see the debris cloud looks bigger, simple geometry can give a surprisingly accurate distance.
for example:
If I am watching a kid blow up a balloon miles away thru a telescope, and make a rough estimate of how fast kids can blow up balloons, knowing the magnification of the telescope and how big the balloon appears to be getting, I can figure out (if I were younger and remembered high school geometry better) how far away the kid is.
If I just assume all balloons are the eventually the same size, I can figure how far away all the balloons I can see are.
Technique would be similar for cars instead of balloons, stars instead of cars, galaxies instead of stars. If I figure out there are different kinds of stars then I can be more accurate if I figure out what kind of star I'm looking at, same for galaxies, the more I know the more I can find out.
The spectrum of distant galaxies also show absorptions at different Doppler shifts from gas clouds between here and there. And the further out we think we are looking, how about that, more lines of absorption appear because there are more gas clouds along the way.
It all hangs together. We don't see stars that are Cepheid variables in galaxies shown to be too far away for us to see them. So, things we don't see also help. As telescopes improve, we can see Cepheid variables further and further out, lo and behold, they are are consistently distant with the distances already worked out via other means. So stuff we didn't see because it was too far/too faint at one time, that later becomes visible with better equipment helps establish confidence in what was worked out before with lesser equipment.
At some point (I believe the estimate is 30-40 years) we should have equipment to directly detect changes in the Doppler shifts of extremely distant objects that are caused by a possible acceleration affect, or rule out that theory if a decel is detected.
Unlike religion, cosmology doesn't need special pleading, reliance on 'belief', or preconceived dogma to work out things. Someone comes up with an idea, develops an observation strategy to confirm/deny the idea, gets a confirmation observation(s) from somebody else, and you've got something.
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