This is definitely Arp nonsense. Images DO NOT prove that two objects are part of the same galaxy at all. You need direct evidence to prove such.
It was an outstanding problem in astronomy for years to determine what things were part of our galaxy and what things weren’t. It turns out that you need to look for distance indicators. Arp dismisses such efforts as spurious. Unfortunately, this is just grandstanding and arrogance, AFAIAC.
I challenge you to name one.
The help you are looking for is going to be hard in coming. For example, here is a Hubble Image that looks like it has a mirror image of itself inside the galaxy! This is undoubtably a weird coincidence of a more distant galaxy that is similar in type to a galaxy that is in the foreground. Thing is: this type of galaxy is very rare so the Arpists start yelling that it must be that standard theory of astonomy is incorrect. They don’t understand statistics: chance occurrences of convergeances will occur and sometimes you will happen on a rare one. That’s the way it works.
I think it’s time for me to be wise and concede at this point. As I said I feel as I’m still scratching the surface of this fascinating subject, - and you’re obviously an expert.
A couple of questions though (in the interest of learning):
How do we know how much dark matter there is in the universe? Is it measured by gravitational “inconsistencies”, or by some other method?
And how much of “our” universe can we really see, according to the very latest figures?
No, it’s not a question of looking for “inconsistencies”. According to the recent, highly impressive, WMAP results, about 23% of the total energy in the universe is dark matter. This experiment looked at the variations in the microwave background radiation. Just such variations had been predicted - indeed looking for them was pretty much the motivation for launching the mission in the first place.
WMAP is looking back as far as it’s possible to “see” anything. Look any further away and the universe is opaque.
bonzer hit it on the nose, but just in case you didn’t get it:
WMAP nailed not only what the mass fraction of the universe had to be but also how much of that mass can interact with light (so-called baryonic matter). It turns out that 90% of matter doesn’t interact with light. Lo-and-behold that’s the same result you get if you just go out looking for baryonic matter to dark matter ratio “discrepency”.
I want to get back to the issues raised by the OP for a minute here…
We don’t just happen to be in the area where everything is moving away from in all directions. If we were in some other area, we would STILL observe everything moving away from us in all directions. The whole Universe is expanding, increasing the distance between objects, and “stretching” radiation into longer wavelengths. The farther away something is, the faster its distance from us is increasing, and the more red-shifted its light is.
What they have done is use as many observations as possible to figure out just how fast the Universe is expanding.
What the Hubble helped to do is figure out, by means of accurate observations and data collection, is provide scientists with the means to determine just how far away the farthest observable objects are, by measuring the redshift of their light. Your source is telling you that (after various other influences are taken into consideration) this number is 12 billion light-years. By definition, then, the light we see from the farthest visible objects is 12 billion years old. Light from anything older than that would have taken that much longer to reach us, which means it would have to be that much further away, or we would have seen it by now.
We therefore conclude that the Universe is 12 billion years old.
By your term “regional universe”, I assume you mean the idea that, somewhere beyond our ability to see, couldn’t there be somone observing the Big Bang from their vantage point, with no idea that WE exist?
Sure there could be. But we have no way of knowing yet.
Again, we believe the Universe to be 12 billion years old because we can see light from things that are 12 billion light years away, and we can’t see light from anything 17 billion light years away. That does not mean that we don’t think there IS anything 17 billion light years away. As a matter of fact we DO think there’s probably stuff that far out, but we have nothing to suggest that it is radically different that what we can see now, so it’s not mentioned frequently. Our logic tells us, however, that if the Universe were that old, we would see light from those things.
A couple billion years from now, some observer will see the light from things 14 billion light-years away, and figure that the Universe is then 14 billion years old, even though there’s probably still stuff further out than that.
Let me see if I can simplify this (correctly, I hope).
No. See below.
Yes and Yes.
First, forget about multiple big bangs. That would mean there are multiple universes. Maybe there are, maybe not but let’s stick to our Universe.
We estimate the age of the Universe to be 13.7BY old. But inflation as described above means that the size of the Universe is NOT 13.7 billion light years in size. One model of inflation puts the size (radius) of the Universe as 10[sup]10[sup]12[/sup][/sup]! That’s one followed by a trillion zeros. What units is that you ask? It’s centimeters, but that number is so big the units don’t really matter.
Now imagine a planet trillions of lights years from us. We cannot see this planet because it is beyond the horizon of our observable universe which has a radius of 13.7 billion light years. If an astronomer on this other planet were to make the same measurements that we have, she would find the age of the Universe to be 13.7BY – same as our result.
So just remember that when you hear talk about the “universe” it is usually shorthand for the observable universe. The result of the big bang is the (capital “U”) Universe. The part we can see is just a small piece of the total.
