ALMA sees old galaxies before they merged. two ways to look back into the past?

Ahhh, I didn't know that, what caused this name change? Because Galaxies are made from the stuff of our universe and thus cannot be called "independent from our universe?

As I understand the hypothesis, in a multiverse some universes have completely different composition and mathematical laws. I believe Hawking proposed that due their very difference, some universes are very short lived and only or a few universes (if any) had the composition of ingredients similar to our universe which has enabled them to survive , a form of Darwinian Evolution and Natural Selection on a universal scale, a probabilistic function.

 

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From Wiki when google Island Universe.

The Great Debate, also called the Shapley–Curtis Debate, was held on 26 April 1920 at the Smithsonian Museum of Natural History, between the astronomers Harlow Shapley and Heber Curtis. It concerned the nature of so-called spiral nebulae and the size of the universe; Shapley believed that distant nebulae were relatively small and lay within the outskirts of the Earth's home galaxy, while Curtis held that they were in fact independent galaxies, implying that they were exceedingly large and distant.

The two scientists first presented independent technical papers about "The Scale of the Universe" during the day and then took part in a joint discussion that evening. Much of the lore of the Great Debate grew out of two papers published by Shapley and by Curtis in the May 1921 issue of the Bulletin of the National Research Council. The published papers each included counter arguments to the position advocated by the other scientist at the 1920 meeting.

In the aftermath of the public debate, scientists have been able to verify individual pieces of evidence from both astronomers but on the main point of the existence of other galaxies, Curtis has been proven correct.


Shapley was arguing in favor of the Milky Way as the entirety of the then known universe. He believed that "spiral nebulae" such as Andromeda were simply part of the Milky Way. He could back up this claim by citing relative sizes—if Andromeda were not part of the Milky Way, then its distance must have been on the order of 108 light years—a span most astronomers would not accept. Adriaan van Maanen was also providing evidence to Shapley's argument. Van Maanen was a well-respected astronomer of the time who claimed he had observed the Pinwheel Galaxy rotating. If the Pinwheel Galaxy were in fact a distinct galaxy and could be observed to be rotating on a timescale of years, its orbital velocity would be enormous and there would clearly be a violation of the universal speed limit, the speed of light. Also used to back up his claims was the observation of a nova in the Andromeda "nebula" that had briefly outshone the entire nebula, constituting a seemingly impossible output of energy were Andromeda in fact a separate galaxy.

Curtis on the other side contended that Andromeda and other such "nebulae" were separate galaxies, or "island universes" (a term invented by the 18th-century philosopher Immanuel Kant, who also believed that the "spiral nebulae" were extragalactic). He showed that there were more novae in Andromeda than in the Milky Way. From this he could ask why there were more novae in one small section of the galaxy than the other sections of the galaxy, if Andromeda was not a separate galaxy but simply a nebula within the Earth's galaxy. This led to supporting Andromeda as a separate galaxy with its own signature age and rate of nova occurrences. He also cited dark lanes present in other galaxies similar to the dust clouds found in the Earth's own galaxy and massive doppler shifts found in other galaxies.

Curtis stated that if van Maanen's observation of the Pinwheel Galaxy rotating were correct, he himself would have been wrong about the scale of the universe and that the Milky Way would fully encompass it.


After the debateEdit
It later became apparent that van Maanen's observations were incorrect—one can not actually see the Pinwheel Galaxy rotate during a human lifespan.

Due to the work of Edwin Hubble, it is now known that the Milky Way is only one of as many as an estimated 200 billion (2×1011)[1] to 2 trillion (2×1012) or more galaxies[2][3](containing more stars than all the grains of sand on planet Earth),[4]proving Curtis the more accurate party in the debate. Also, astronomers generally accept that the nova Shapley referred to in his arguments was in fact a supernova, which does indeed temporarily outshine the combined output of an entire galaxy. On other points, the results were mixed (the actual size of the Milky Way is in between the sizes proposed by Shapley and Curtis), or in favor of Shapley (Curtis' galaxy was centered on the Sun, while Shapley correctly placed the Sun in the outer regions of the galaxy).

End
Alex

 

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If not, then how can we make any estimations of its size or that it is expanding? The statement that the universe could be much bigger than what we estimate is meaningless as long as , or unless, we assume it is finite.

Moreover, quantities are also meaningless in context of expansion of the universe. We know it is very big and has as many stars or even galaxies a grains of sand on earth, but that still does not prove anything about "expansion". If our universe is expanding spacetime with a beginning and a hypothetical ending, it has to be finite. If there actually is a multiverse, each universe would have had a beginning and an hypothetical ending.
So what is the "infinite boundless condition" in which all this activity could even be possible.

This is the reason for my proposal of an "a priori" infinite condition where time has no meaning and which does not consist of space nor time. An abstract condition which by some (mathematical?) mechanism generated dynamical "hotspots" which the became expressed as multiple but separate universes, some which were mere "blips" of spacetime, some which were "durable" constructs, such as our universe, which is still dynamically expanding. CDT (causal dynamical triangulation) attemps to explain this universal expansion by a triangular fractal function.

https://en.wikipedia.org/wiki/Causal_dynamical_triangulation

And that would be specific to our universe (spacetime fabric). Somehow, I see a paradox.

 

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It is possible if there was a positive curvature to the universe: http://abyss.uoregon.edu/~js/images/universe_geometry.gif
However, the universe is (almost perfectly) flat on large scales, so no, there won't be two paths in opposing directions to a single event, back up to the inflationary period. During the inflationary period, the universe expanded faster than the speed of light, which complicates matters greatly.

So it's not the "true" center of the universe; it only looks like it. If everything is at the center, then nothing is at the center, because clearly the term has lost its meaning in such a context.

That might be related, but it we're talking about times after the inflationary period, it shouldn't be.

The universe isn't expanding into another space, the space inside the universe is expanding. And time is caught up on the inside of the universe, if "expanding into time" even is something that's possible.

Assuming the BB happened like that, the BB was (per construction) everywhere. It happened at all points at the same time. The artist rendering of a point exploding are very, very wrong in this regards.

 

What did you do to the Write4U that in post #5 (and post#11) admitted that there is no center of the universe?

 

The inflating balloon seems like a good analogy to me. The universe is the balloon. We are inside the balloon. It expands. It makes no sense to say "what is it expanding into".

At the Big Bag the balloon was not inflated. If you put dots all over the uninflated balloon, that relationship between the dots stays the same as the balloon is inflated. That's why there is no center. All relationships stay the same.

I think, when people are talking about an infinite universe that they are just allowing for all the possibilities. The evidence is pretty good from the BB to the present as an explanation for our universe.

There are differing scenarios that play out depending on the shape of the universe. There can be a collapsing universe, a continually expanding universe or a perfectly balanced universe. It's possible that the universe has always been here and that it's infinite but there is no evidence for that so it just has to be a possibility.

 

I like the bread analogy with raisins... Mmm raisin bread.
Alex

 

How far back do observations take us?
Not past CBR I expect.
Alex

 

Right.

 

If the Steady State Model predicted background radiation first would it still be an option.
I have always thought inflation unlikely (the universe expanded practically to all we can observe in a instant) although I was assured here the theory of inflation was reasonable, however the problem with the big bang the theory of inflation sought to fix would seem not to be a problem with the steady state model.
The expansion was observed and the big bang theory presented but problems arose which a futher very rapid expansion in effect saved it.

Is that correct?

And it seems observation stops at CBR so could the start go back further in time, at least far enough to remove the problems that inflation fixed.
Alex

 

I'm no expert here however the BB is currently the best explanation for the data. I don't think it makes sense to talk about the BB and then talk about going back further in time. That wouldn't be the BB and it wouldn't reflect the data that the BB currently explains.

You can't see past the CMB era because it was too hot for photons to exist (it was just a plasma).

The Solid State Model predicted a steady density state throughout the universe with density being created as space expanded. It also predicted a commonality of space (the same everywhere). I think there were many problems which no longer fit with the evidence of today.

 

Infinity has no center.

But if our universe expanded from a singularity, that would logically be the center of the expanding universe that is, if the expansion was in all 3 dimensions (spherical) regardless of the rate of or size of expansion .

However, if the universe expanded in a bellshape configuration (as per illustration) the center of the expanding universe would lie in the past, thus it would no longer be the center if the universe as it exists today. It would be the center only of the BB itself and after that, could only be called the center of the beginning, regardless of the subsequent shape the universe might form.

If anything, the balloon example explains that very fact. The air comes from a single source which lies in the past of the inflating balloon shape, thus the balloon would have only a center of origin (the air inlet) but would not be expanding from the center outward in 3 dimensions from the inlet, and actually looks more like a closed bell shape than a sphere expanding from a central point.

Painting dots on the balloon only shows that the balloon is expanding, but would not prove the center of the inflationary force. We can create the same dots on the surface of a bell shaped universe and achieve the same effects of spacial expansion.

Please understand that I was only addressing the original question as it was posed.

Personally I am in favor of a 3 D Toroidal shaped universe which has no center in and of itself but encircles a single point which might possibly be a hidden (dark) White Hole spewing energy along the 2 dimensional surface which seems to expand until it reaches an equator (along the outermost diameter of the torus) and then begins to contract back at the other side, possibly back into a hidden (dark) giant Black Hole. I assume that this "doughnut" concept also has its problems, but it has been proposed and if we were to paint dots we would see the same effect of spatial expansion, except that after passing the equator space would seem to be contracting again.

OTOH, it might possibly provide answers to the questions about spacetime curvature, dark energy, dark matter, and the concept of infinity.

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A toroidal model of the universe which has superficial similarity to the theory described in this article.

https://en.wikipedia.org/wiki/Three-torus_model_of_the_universe

This model would also not exclude inflation of the entire toroid. Intuitively it seems an elegant solution to a lot of questions, if our current knowledge would allow for such a configuration.
My lack of cosmological laws prevent me from seeing any fatal flaws. Someone?

p.s. found a link to possible toroidal shapes;
https://images.search.yahoo.com/yhs...ontent/uploads/2011/12/Torus.jpg&action=click

 

You can't base all of your conceptions of the Big Bang from an illustration designed to make a specific point. There is no bell shape. That is just to convey the passage of time in that illustration.

The balloon example isn't to be taken too far either either (regarding the "air inlet"). If you want a real explanation you have to read a real book describing the theory.

It's best to spend your time and energy to accept and understand the theory (with all the supporting evidence) before coming up with some other theory which isn't supported in the same way.

 

Right, and because it's possible our universe is infinite in size, talking about the center of our universe as if it exists is incoherent.

False; if the singularity encompassed all of space (i.e. space was "the same size as the singularity") then the singularity was everywhere.
Let's look at it another way. Let's say we (magically) anchor ourselves to our current position (i.e. our space coordinates will not change) and we start traveling back in time. After traveling 13.8 billion years into the past, we would notice that the singularity is at our position. In other words, the singularity happened here (at this position).
Now let's pick a position in some other galaxy, far far away, and do the same thing. Once again, after traveling 13.8 billion years into the past, the singularity would be at that position. In other words, the singularity happened there (at that position) too. We can do this for all positions. Conclusion: the singularity happened everywhere. So, if the singularity happened "at the center", then the center is everywhere, which is meaningless.

For a more mathematically rigorous derivation, just take the FRW metric, and start going back in time (i.e. make the scale factor smaller). Once you reach a = 0, there's your singularity, and space is compacted into it. The singularity happened everywhere; there is no center.

That's not what the illustration depicts, so that's wrong.

Are you saying the space coordinates of where the center is/was cannot be reached anymore? That requires a hole in space, like a doughnut. This is certainly not compatible with standard cosmology, and isn't even compatible with your bell-shape configuration.

That's twisting the definition of "center" so far, you ought to be using a different word.

The inlet of air of a balloon is not at the center of the balloon for any reasonable definition of the word "center".

What does "the center of the inflationary force" mean?

And you've proven you don't understand your own illustration. How do I draw dots on a surface that extends in time, not (only) space? These dots would "appear" on the edge of the universe, and then disappear again. What do these dots symbolize? Certainly not galaxies, as they are often taken to symbolize when people talk about this comparison. You have twisted the original idea of the balloon so far, it's become incoherent.

Why did you feel the need to introduce an incompatible definition of "center" then, a definition that is completely incompatible with standard cosmology? Why respond with pseudo-science and fringe theories on a thread that's in the main science section, and doesn't seem to contain any references to pseudoscience and fringe theories?

Ah, so I was right about a hole in space! Next time, please either restrict these non-standard cosmological views to the appreciate sub-forum, or up-front own up that you're not talking about standard cosmology.

(The rest is off-topic and not standard cosmology.)

 

OK

How about "origin"?

There is only one hole in the balloon where the inflationary force can enter the balloon. Close that hole and the balloon stops inflating.

the dots are present on each slice of time and with each slice of time the dots have moved farter apart.

So you know the exact formation, shape and size of the Universe? You should make that an entry in Wiki. I'd probably use it as a link. Do you think I drew that bell shaped universe?

You know for this for sure? 99.99999999% for sure. I see a Nobel prize in your future.

Seems to keep you interested.

p.s. Just for fun, here's one for you. It is real science, but not necessarily pertinent to the OP.

a) Three pipes connected with a T joint. The main inlet pipe has a shut-off valve, and one of the other pipes also has a shut-off valve. The main pipe is connected to a compressor, the other two pipes are attached to balloons.
b) I "open" both valves and turn the compressor "on". Both balloons begin to fill at the same rate.
c) At a certain point I turn "off" the valve in the pipe leading to one balloon and it stops inflating, while the other balloon continues to inflate.
d) After another period of time I turn "off" the valve in the main inlet pipe and "open" the valve in the pipe leading to the smaller balloon. At this point both balloons have an "open" connection.

Q: What will be the result between the two still connected but differently inflated balloons?

p.p.s. This is not a trick question.

 

That's a lot better!

Sure, but that hole is not at the center of the balloon at all; it's at the very edge.

Aha, so you are saying the illustration is not at all similar to the balloon analogue.

Are you being intellectually dishonest, or is your memory failing you again? I explicitly stated in this very thread that we don't know the shape or size of the universe.

No, but you interpreted it as if it was the real shape of the universe.

I'm 100% sure that the "hole in the middle of space" idea is not part of standard cosmology. I won't be getting a Nobel prize for that statement, because it's cosmology 101.

Actually, no. Your off-topic ramblings are tedious, often wrong, and (by definition) off-topic. But you keep doing it; it seems to keep you interested.

How is this relevant at all? Either make a point, or start a new thread with your question.

 

I never said that. I explained specifically the center point (the singularity) of the universe lies in the past, not in space.

Right it is in the past of the expanding balloon. By your logic a balloon has no center either even though it is spherical in shape, and I would agree to that.

But even then, not all balloons are spherical either, I have seen long thin balloons which people use to create all kinds of artistic constructs. Cosmic inflation is not necessarily in a pure 3D spherical form either. And I believe that is also mainstream cosmology.

Aaaaw, such a simple question. We were talking about balloons, no? It doesn't warrant a separate thread. It just requires a very simple answer and may not be all that far removed from this discussion.

 

Yes, you did. You said: "Personally I am in favor of a 3 D Toroidal shaped universe which has no center in and of itself" in post #72. A torus has a hole where its center is; it's its defining characteristic.

No, it's at the edge of the space "contained" by the balloon. The hole is always present, so it's not purely "in the past of the expanding balloon".

Please, don't put such non-sense in my mouth, and look up what a "center" is, specifically when dealing with spherical objects instead.

Yes, of course, because you came up with it in the first place.

But those are not the balloons used in the analogue, so that's irrelevant.

It's indeed not demanded by the FRW metric, but experimental evidence strong suggests that is was.

But still irrelevant.

Specifically, the balloon analogue. You however seem interested in balloons themselves; that's not what we were talking about.

You want to talk about balloons, not galaxies and universal expansion (the subject of this thread). So yes, this is not the thread to talk about balloons.

If it requires only a simple answer, why don't you give it yourself? And then prove that it is relevant to the discussion at hand.

 

Why does every thread in the science forums end up about non-mainstream science? Is there no one on this forum that likes to discuss mainstream science in the mainstream science forums?

 

I admit at least some involvement, but to the best of my knowledge, I have not posted non-mainstream science content. However, if it comes up, I do tend to respond to it. If that's deemed to be unwanted by the moderation staff, I am fully willing to stop doing that.

I think this thread is a prime example of it. The thread's OP started out fine (no reference to pseudo-science or fringe), but it was introduced at some point, and things only got worse from then on.