My name is Dave and I'm trying to get a handle on the current dimensions of the Universe. How many miles (or whatever distance figure is appropriate) from the center of the Universe to the outer known limit?

What is the distance from the center of the Universe to Earth?

Assuming the Universe is flat, what is the ratio of the horizontal to the vertical?

What is the distance that our present telescopes can see? To the center? Beyond the center? When aimed along the vertical line, I assume everything is black past a certain point?

Thank you for any information you can send me.

No-one has managed to find the centre of the Universe yet.

Or even if they have, it didn't have a sign on it.

Firstly as mentioned the centre of the universe is undefined. Secondly the actual true size of the universe would be an estimate based on how far away the outer most detectable objects are. The current estimate IIRC is about 13.7 billion light years from the earth to the furthest most detectable objects. But remember that the universe is inflating at a very high rate and possibly subliminally at the furthest regions. Some of the more knowledgeable folks on this forum will explain it in more detail

If the universe is flat does that mean there would be a physical barrier or wall that defines the end of the universe? Obviously we cannot catch up to the inflation's leading edge but what if we could - What would we see? I just cannot get my head around that concept.

As currently conceived, there is no center. As an analogy, imagine the surface of a balloon is the entire universe. No inside, no outside, just the surface. Where is the "center" of such a universe? Well, there's no such thing.

Since there is no center, some will point out that any point in the universe could be considered a "center," in which case the answer to your question would be zero.

From all indications and observations, h:v = 1:1.

The Hubble Ultra Deep Field should give you some idea.... Remarkably, your TV set tuned to an off channel can pick up and display photons that have come from the farthest distance possible - about 13.67 billion lightyears. (That's a lot of miles. )

When aimed in any direction whatsoever, beyond 13.67 billion lightyears, we cannot see anything, but not because nothing is there. Au contraire, we see nothing because the universe at that time is so hot and dense, it is opaque. The photons that enable us to see anything keep running into other particles and cannot travel any significant distance, so we can't see anything beyond that limit (and never will be able to -- using electromagnetic radiation, which is the generalized term for light).

I haven't checked Wikipedia's Big Bang article lately, and there's always the chance that it contains some misleading statements, but I'm sure you would benefit from looking it over.

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Everyone is entitled to his own opinion, but not his own facts.

Just to throw in the inflation factor- 46 Billion Light years is our current estimate .
We can see out to 13.7 billion light years, the rest is pushed out of the visible field because of inflation, but if the universe stopped inflating right now then all of that would be visible in about 46billion years

To expand (pun not intended) on what Cougar said (Although Cougar is more educated than I am- just wanna clarify for Dave), Cougar put the word "surface" in Italics to emphasize what he said about no inside to the balloon. It's an analogy, but describing the current observed state of the universe doesn't really fit with what our brains are accustomed to visualizing. So be wary of trying to ask what's on the other side of the surface There isn't necessarily anything there.


Jetlack, I don't personally hold a belief as to the 'edge of the Universe' if such exists. If it did, I would image that it wouldn't be a wall or anything. First off, I imagine we wouldn't be able to travel there or see anything (Imagine a warp gate that took our ship right up to the edge) because if we 'crossed the edge' we would loop back and find ourselves at our starting point.
However, if we assume we CAN "observe" (somehow) beyond the Universe, we still would see a lot of Nothing. Because there isn't space for light to travel through. there isn't light. If you think the Universe is full of void- that's nothing compared to...uh... Nothing.

Can anyone?

Your statement is true for the actual universe. It's not true for the observable universe.

For the observable universe, the following is true:

About 46 billion light years. In Wikispeak: "The comoving distance from Earth to the edge of the visible universe (also called cosmic light horizon) is about 14 billion parsecs (46 billion light-years) in any direction." (source: Lineweaver, Charles; Tamara M. Davis (2005). "Misconceptions about the Big Bang". Scientific American. Retrieved on 2007-03-05.)

0.00000 (use any dimensions you wish - it's still zero)

Flat, how? Like a pancake? If so, the ratio is 1, as it's as nearly spherical as we can tell.

When speaking of great distance, we speak in terms of time, not distance, as the rate of expansion isn't constant, and going back that far introduces a lot of questions as to the exact distance.

Currently, Hubble's Ultra Deep Field has seen, in visible light, back 13 Billion years distant.

Black, white, psychodelic purple... We just don't know, as we can't see beyond a certain point.

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I am Mugs, of the Alien clan of Usa, Nordamerica, a Terran, of Sol. A human.

Whoever says "perception is reality" is daft. It's merely an abstraction, and often not a very good one.

Thanks for the expansion. In fact, I think you should be saying "expansion" instead of "inflation." Although from all indications the universe is currently "inflating," that term is usually reserved for that brief instant during the first second of time when the universe expanded superluminally before settling down to a more 'relaxed' expansion rate similar to what we see today.

To further e-x-p-a-n-d on the topic for Steadman's benefit, one must differentiate between the visible universe and the 'whole' universe, which may be a lot larger (but since anything outside our visible horizon is... not visible, it's very hard to tell much about it). Nevertheless, Alan Guth, who developed the Theory of Inflation, calculated that the 'whole' universe was 10²³ times larger than the visible universe! I mean, the visible universe is pretty darn big, but we're talking 100,000,000,000,000,000,000,000 times bigger! Guth said, "...if the inflationary theory is correct, then the observed universe is only a minute speck in a universe that is many orders of magnitude larger."

Inflationary theory has developed considerably since Guth first proposed it, and it has some observational support, but whether it is correct or not has not really been determined yet.

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Everyone is entitled to his own opinion, but not his own facts.

I'm guessing that's "superluminally" (faster than light) rather than "subliminally" (undetectable by consciousness)?

Grant Hutchison

Ahem. 'Back' 13.7 billion light years, not 'out' 13.7 billion years. We can see 'back' to the CMB, which was a long time ago and was when the universe was very hot.

Welcome back to the circus, NF.

On other OP stuff:

Many people argue that there are parts of the universe forever inaccesible due to the expansion. Personally, I doubt it, I think the ant on the rubber band analogy holds.

The universe is 'flat' as far as we can tell, to within 2 to 3 percent on cosmological scales. This means it is not closed in 3-space, as is a spherical surface in 2-space embeddded in 3 space, and it is not open in 3 dimensions, as is a hyperbolic (saddle) surface in 2-space embedded in 3-space.

There is also zero, zilch, none, nada physical evidence of more than 3 space dimensions and 1 time dimension, but that's another post.

Regards, John M.

edit: There is no reason currently to think that the universe is not infinite, also.

Actually, both do apply

So you figure that if the car keys in your pocket started to expand faster than light, you wouldn't notice?

Grant Hutchison

If it's faster than light, I'm sure I wouldn't notice

Ah well. I suppose if you're absolutely sure, then that's one less thing for you to worry about.

Grant Hutchison

Wrap your noggin around this one...

Different thing, though: that thread's about the addition of velocities under special relativity; this one refers to superluminal velocities arising from the expansion of space.

Grant Hutchison

Yeah, I know. Was just being absolute, considering the pocket.
I dunno, somehow it all fit together for a laugh inside my head, but now I can't figure out why.