I tried doing this, but now the tip of the last pencil doesn’t exist yet. 
You seem to have the pencil pointing away from the centre of the universe then. (it does exist, but not here)
Wait a few eons. It should show up… 
Whoa! My whole post seems to have moved somewhere else. Did it ever exist? Will it exist in the future? I don’t even know who to turn to for help here, a mod or Neil deGrasse Tyson.
Does anyone else see it? I mean, people quoted it, so they must have seen it at one time, but I don’t see it know except in the quotes.
samclem moved it into a parallel universe in the process of vaporizing a spammer and deleting a post by another poster who quoted him. Since your post was an innocent bystander, I have further messed with the space-time continuum and moved it back.
Well, I was destracted by a butterfly I saw, and when I caught it…
Everyone who has attempted to provide an answer has reiterated that “there’s no center” of the universe. I still after all this cannot see why. Here’s my logic. Which step is flawed?
I go take over the Hubble. I point it in any single direction and zoom in as far as I can, and take a picture. I see a galaxy that is very new from the early formation of the universe. It is older now, but I see it as it was nearer to the beginning of the expansion.
Now, I travel through a worm hole (yes, this is flawed, but play along here!) to that distant galaxy. I arrive NOW. I see the galaxy as it is today, fully formed. I look back towards the Milky Way. If I brought the Hubble with, I might see the milky way as it was at the beginning.
NOW, let’s say I look in the same direction that I originally looked. Not back at the Milky Way, but along my original vector. What do I see? A few more galaxies Hubble couldn’t see from earth? Stronger cosmic background radiation?
My point is that the galaxies don’t go on forever. There MUST be a finite spot where galaxies stop, and matter stops. Farther out, there must be a spot that light and energy stop. Where gravity waves stop. Because this point must exist in any direction, the universe has a center point.
Why?
Okay, yes you see the galaxy as it was in the past.
Okay let’s lose the wormhole, let’s just compare what two comoving observers see (i.e. we don’t really need to invoke wormholes). Yes the comoving observer in the far-off galaxy sees the Milky Way at some earlier stage.
Okay we’re looking in the opposite direction to the Milky Way. Obviously we don’t see the Milky Way,but otherwise what we see is pretty much the same, galaxies (some of which may not be visible from the Milky Way) of a simalir distribution to those we see from the Milky Way, the same level of CMBR.
Well the fundamental assumption behind big bang theory is pretty much that galaxies do go on for ever or at least (allowing for the fact that closed universes in big bang theory have finite vollume) that there’s certainly no point where galaxies stop.
If you traveled via wormhole to that distant galaxy, your view would be qualitatively the same as the view from Earth. You’d see other galaxies more or less uniformly distributed in all directions, with the more distant ones receding more rapidly away from you according to Hubble’s law, and beyond the galaxies, you’d see the cosmic microwave background radiation, equally strong aside from slight perturbations, in all directions. The exact details would vary: You wouldn’t see the same galaxies in the same places as we see them, but the general picture would be the same. Your post is like asking how far one would have to sail to sail off the edge of the Earth.
This last paragraph is your flaw. If the universe is infinite, the Galaxies do go on forever. If the universe is finite but bounded, so that the balloon analogy holds, you will eventually circle back to the Milky Way, but you will never get to where galaxies stop.
Steps using my uber telescope:
- Look as far out as I can to galaxies as they were shortly after the expansion.
- Imagine myself on one of those galaxies right now as it is today.
- Look in the same direction out as far as I can.
Repeat steps over and over.
From what I’m gathering, I’ll either
a) Eventually see my original self if the universe is finite and bounded. (Or at least zoom right past myself in one of these large distances I’m peering across).
b) Never, ever see the end of galaxies.
Option A boggles the mind, but explains why there is no center, and fits with everything else I read on the expansion. Option B causes a ‘numeric overflow’ in my head. Why must galaxies go on forever? Saying this seems like someone in the dark ages saying that air must go on forever.
Yes that’s pretty much correct (one can always add caveats to non-technical descriptions)
Assuming big bang comsology is broadly correct then current data stronlgy suggests Option B over option A.
That’s a good question as really more than anything it’s an assumption. But like most assumptions in science there’s fairly sensible reasons for assuming them.
Think about a universe consiting of a finite volume of galaxies surrounded by an infinite void. Why in the infinite volume of the universe would there be a finite volume that is completely different in character to the rest of the universe? Also in order for the universe to appear as isotropic as it does to us we’d have to be pretty much at the dead centre of this finite volume of galaxies, clearly a violation of the Copernican principle.
Translation of what Chronos just said, in layman’s english (I believe, correct if wrong):
If the universe is infinite, and you’re traveling away from our galaxy, you will always see the same sorts of things, forever. If the universe is not infinite, and you’re traveling away from our galaxy, sooner or later you will run into our galaxy, and you will still always see the same sorts of things.
Is that reasonably accurate?
That’s what I’m getting too (see my previous post). I still don’t see why galaxies would go on forever.
I never thought of an infinite void.
<MyOriginalWrongThinking>
The expansion was the entire universe. There was nothing ‘before’ it, nor nothing outside of it. You couldn’t be an observer watching since the expansion was everything. There was no time or space ‘before’ it. So I never pictured an infinite void. The void as you put it can only exist inside this expansion. I pictured the entire universe being a sphere shape expanding from some point. What’s outside the sphere? Nothing, it does not exist. That’s an erroneous question, like what would happen if I accelerated past light speed… But in that thinking, there’s a definite place that matter ends, followed by light soon after, followed by gravity waves after that.
</MyOriginalWrongThinking>
I’m still not sure why the theory is that galaxies go on forever! On one hand, I could chalk it up to ‘better minds than me understand it, therefore I should accept it’. On the other hand, many ideas in cosmology seem to change often. There’s a fine line between genius and insanity and this topic seems to walk it. Heck, I still don’t accept dark matter.
Please don’t do this. That’s counter to the whole notion of science. It would be best, of course, for you to come to be able to understand the evidence and reasoning yourself. But lacking that, it would be better for you to continue to doubt than to blindly accept things just because someone tells you they know better.
As for a sphere with a boundary, like you’re picturing: What would happen if you got in a spaceship and attempted to fly past the boundary? If you’re able to do so, what was to stop stars and galaxies from also flying past that boundary? And if you’re not able to do so, what’s stopping you?
And dark matter is a bit off-topic for this thread (but feel free to start a new one!), but in brief, there are a whole bunch of independent lines of observational evidence which lead towards dark matter, and it’s not all that theoretically surprising that there should be some out there, anyway.
For the most part, I don’t blindly accept things. (Again another thread, and likely another forum, but I call that religion, not science). If my original view of things was correct, I still could not pass the sphere because to do so would require speed greater than light.
There is no sphere - a sphere is a shape defined by a 3D view of the interior of our universe. It has no meaning in an external universe sense.
The problem is you’re trying to visualize and describe something that our language is not equipped to describe. So the best you can cone up with is analogies, which are flawed by definition. The only language these things can be described in is that of mathematics. It’s all very unintuitive.
You’re searching for a description which describes our universe; but there isn’t one. You’ll be forever frustrated by continuing to seek an image you can comprehend. The math is the only way to describe it.
Every once in a while I like to remind people that there is no reason our “common sense” thinking should apply to the universe - or to subatomic particles, for that matter. It’s not a problem that the math is unintuitive and that everyday language doesn’t describe it.
It would be a problem, in fact, if you **could **describe the universe in familiar, commonplace terms. That’s the way people used to do it. And it was all wrong.
The realization that you can’t possibly “get it” when it comes to cosmology or QM or relativity is the best sign that the Ph.D.'s finally got it piled high and deep enough.
Feeling humbled yet? 
I am.
You know, I always thought I had a reasonably good grasp on these things for a layman, and that’s what I always thought, too: that when cosmologists talked about an infinite universe, what they meant was that a photon emitted from any point in the universe, if it was never absorbed by another particle, would continue to travel infinitely far in a straight line without ever crossing the same point in space-time (which is what would happen in a finite-but-unbounded universe). Likewise, I believed that at each point on it’s path, an observer situated there would see the universe as relatively isotropic, which is to say that an no point would there be fewer galaxies ahead of the photon than behind it. (Nevertheless, from the perspective of an observer along the path of the photon, the photon would pass through galaxies less and less frequently as it travelled due to the continued expansion of the universe.)
I was quite certain, though, that the number of galaxies (and stars, protons, etc.) was finite. I’d have thought an infinite amount of matter was only consistant with a steady-state universe. If the amount of matter in the universe is infinite, as well as space-time being infinite, in what sense is the universe expanding?