someone was trying to tell me that the big banghas been disproven because they found older galaxies moving in the opposite direction....

i've been asking this person for a link for some time and they just don't respond to it, so it's possible that they made it up, but has anyone else heard this? if so, was the source actually credible?

Since the BB has not been disproven, I'm guessing the source wouldn't be credible. :wink:

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"The oxen are slow, but the earth is patient."

Wouldn't an explosion throw matter in all directions anyway? If so, there wouldn't be a "wrong" way...

That makes sense. Because, if one galaxy is going opposite to the other galaxy, that just means it blew out on the other side.

Have I massacred the language of the big bang theory enough with that statement, or shall I continue?

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"The oxen are slow, but the earth is patient."

yeah, i'm supposing that it's made up. i mean, if i was to go about saying something like that and asked to produce evidence, then i would do so... i'm sure most people would...

i mentioned that even far away from us (earlier in the universal timeline) that gravity would still be in effect, thus perhaps some of these distant galaxies were moving in the direction opposite what was expected because they could be being pulled by the gravity of a galaxy that is in between us and the galaxy that is moving oddly...

Maybe I didn't understand your first post. Are you saying that the galaxies started out in one direction, and then changed to the opposite direction?

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"The oxen are slow, but the earth is patient."

well, no i'm assuming that this guy was saying that there are galaxies that are really far away that are moving towards us rather than away. or perhas just not as far away as quickly.

Maybe they finally made it around the curvature of space. I mean you will only be travelling away for so far then youwould be getting closer right?

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The More I learn, The More Ignorant I Become

Eagle Eye Observatory

This galaxy is known to be moving towards us. It has no relevance to the BB theory. It is the effect of local movement, but on the big scale, everything else is moving away.

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The real news, including science news corporations may not allow on stations they own. http://www.democracynow.org/

i know that. this guy was talking about distant galaxies though...

The significance would depend upon how distant "distant" is. It also depends upon what you mean by moving toward us.

The more distant the galaxy, the larger its redshift will be. In the BB Theory this is interpreted as resulting from expansion of the universe and therefore the interpretation is that the galaxy is moving away from the Milky Way. Taking the Hubble Constant to be 70 km s-1 Mpc-1 we can say that a galaxy at a distance of 100 Mpc should have a redshift velocity of 7000 km s-1 - or be moving away with a velocity of 7000 km s-1.

However, galaxies can have peculiar motions due to orbital motions in clusters from gravitational interactions. If a galaxy is approaching us in its orbit with an orbital velocity of 1000 km s-1 (even as it recedes overall with the expansion of the universe), its redshift velocity will be 6000 km s-1. If this is what you mean by approaching, then there is nothing unusual.

Now if you mean the galaxy is blueshifted instead of redshifted, then its distance becomes important. The most distant galaxies with blueshifts are in the Virgo cluster. For example, NGC 4569 in Virgo has a redshift velocity of (minus) -137 km s-1. Depending upon its exact distance (12-17 Mpc) it has a peculiar motion of about -1000 km s-1 to -1500 km s-1. This is considered acceptable as a peculiar motion and does not necessarily indicate anything unusual.

However, if you had a galaxy at 100 Mpc with a measured blueshift, then that would be highly problematic because its peculiar motion toward the Milky Way would be greater than -7000 km s-1. In other words it would be moving against the Hubble flow at that speed. It is generally acknowledged that peculiar motions should not exceed 1500 km s-1.

Actually, there is no evidence for a center to the Big Bang, and no "other side" of an explosion. Its not an explosion filling empty space, time and space were also formed out of the begining, and the universe we observe "today" appears in the largest scale to be expanding from everywhere.

We happen to be "here" so it appears to be expanding away from us, but if we were located anywhere else, for expample in the Andromeda galaxy, distant galaxies would appear to be expanding away from us there. If we were in one of those very distant galaxies, the cosmos would appear to be expanding away from us there too.

OK, so maybe this is one of those dumb questions, but...

Some Native Americans judged distance by "looks". In other words, look as far as you can, when you get there, look again, etc. 4 or 5 "looks" was a far piece on the plains, not so far in the woods.

So, if we look at the most distant galaxy Hubble can resolve, and we were able to place ourselves there and looked again in the same direction, what would we see? How about after 4 or 5 "looks", 10, 100?

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Can't take the sky from me.

There is blueshifting in some of the Virgo supercluster, this stuff should be a long ways away, so blueshifting is quite extraordinary, but not even close to definitive. The big bang does not put firm limits on proper motions that are against the general grain of the expansion.

If there is intrinsic redshifting in the Virgo supercluster, the blueshifting is a little easier to explain, but not much.

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jwj

It's ok not to know.

I'm tempted to say "weapons of mass destruction", but I'll resist the urge...

Seriously, (and willing to be corrected by better cosmologists than me, i.e. almost anyone), my understanding is that we don't know. Because nothing can travel faster than the speed of light, anything further away than B light-years, where B is the age of the Big Bang, can't be seen and can't influence us in any way, and so is unknowable to us.

Right, at that distance the peculiar motions needed to account for the blueshifting would be about 1000 - 1500 km s-1 which is still considered acceptable. Now if you get beyond 40 Mpc and are finding blueshifts - that is quite definitive.

True. It is generally agreed that the largest peculiar motions should be found in large clusters like Virgo and should not exceed 1500 km s-1.

JohnW.
Everyone knows that Saddam sent the WMD to Syria and that after the Iraq deal is done and the are a few thousand Marines standing around with nothing to do.....Can you say "NEXT!"?

Bad guys are always bad guys but sometime the good guys have a few bad ones in with them too.

Seriously, that part about being "unknowable" really bugs me. Not that it is unknowable to me (I'm dumber than a box of rocks) but SOMEONE, SOME TIME should (I think) be able to know this or at least have a theory. My theory is that you would either return to your starting place or out-distance the expansion and come to see nothingness.

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Can't take the sky from me.

Disclaimer: I'm basing this on a 20-year-old physics degree which I haven't used much since. The following is an attempt to cross the Atlantic in a lifebelt.

Barring some new physics (e.g. if general relativity were disproved), it might really be unknowable. The universe is about 13.5 billion years old, I think. This means anything more than 13.5 million light years away is invisible, because light hasn't got here yet. Not only that, but because nothing can travel faster than light, no other information of any kind can have got here yet. I'm sure it does bug you (it bugs me), but that doesn't mean it's not true.

What can be said is that given that there's nothing special about our position (i.e. we're not in the "centre", whatever that means), and that the universe has no "edges" (whatever THAT means), I think the view from the most distant galaxy would be... more of the same. But we may never know for sure what lies beyond the limits of observability.

I just had a wild thought. What if the universe is not expanding? No wait, hold on. What if the universe started out at a certain size and everything in it is decreasing in size. The scale would increase at a certain rate, or even accelerate. So while a galaxy cluster might have been 1/1000 of the volume and mass of the universe (for argument's sake), now it is the same mass but in an infinitely smaller volume 1/10,000,000 of the volume of the universe, an infinitesimal fraction. With 99.9% of mass being empty space between electrons and nuclei, it could continue to increase in scale and thus become infinitely smaller in volume before quantum collapse. This is a really wierd thought... anyone ever mention this before? These are the kind of thoughts I have late at night.

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"Oh no no no I'm a rocket man Rocket man burning out his fuse up here alone." -- Sir Elton John

J Pax

Jpax, Hi! Just spotted your post.

It brought to mind the rather different thesis advanced in a reader's letter to The Economist back in 1986. (Note that the word “inflation” is used in the economist's sense, i.e. of diminution in value).

See, even wierder thoughts than yours are possible!

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"True skepticism encompasses not dismissing evidence because it seems to defy rational explanation."