leaving the universe 2: 158 billion light-year wide universe

[mopc]

Hey! On leaving the universe 1, I asked what a trip outside our cosmos would be like, assuming a 30 billion lightyear wide universe. Now I read just a moment ago on space.com the following

http://www.space.com/scienceastronom...ay_040524.html

about new measurements on the size of the universe. They say it's actually close to 158 bln ly in diamenter, because since the beginning some 13 bln years ago, the space in which light travelled has also expanded, as far as I understand, and I don't inderstand very far

"It can be thought of as a spherical diameter is the usual sense" said the scientist in the article.

Now, assuming the science in this article is correct, could we at least come closer to the "edge"? I don't even know what to ask anymore, since usual vocabulary turns pathetic when applied to the whole universe 8-[

Could we at least imagine, theoretically, what the edge of the universe and crossing it might be like?

[Normandy6644]

Well, understand that although we see a "sphere" of about 14 billion light years in all directions, that doesn't mean that's the entire size of the universe. That's just the area that has had enough time for light to reach us. There could be many other areas of the universe that don't "overlap" with ours, so to speak. So it could be much much larger.

[harlequin]

Well, understand that although we see a "sphere" of about 14 billion light years in all directions, that doesn't mean that's the entire size of the universe. That's just the area that has had enough time for light to reach us. There could be many other areas of the universe that don't "overlap" with ours, so to speak. So it could be much much larger.

Plus the space within the universe is expanding...

mopc, imagine a photon that traveled 14 billion years. If the universe was not expanding that implies the universe is at least 28 billion light years across since would have sent photons in the opposite direct as well and since Big Bang cosmology does not have any favored locations in the universe. But in an expanding universe, that object can be now a whole lot farther from us than 14 billion light years. Imagine an expanding universe with two objects that are not moving with respect with one another. As the universe expands the distance between them would grow not because of their motion, but because there is simply now more space between them. This effect is only noticable for galactic distances which is why you don't see everything going away from you. The larger the distance the larger the effect.

It is also possible in a "Big Bang" cosmology for the universe to be infinite or initially very, very large from the very start.

[Brady Yoon]

Does this mean that the universe expanded faster than the speed of light?[/quote]

[Russ]

There is at least one other possibility. Cosmologist don't have a damn clue what is going on and the explanations are based only on what has been observed so far. In My Humble (or should I say Hubble?) Opinion, cosmologists have examined, so far, the equivelent of one grain of sand and cannot yet tell whether we are on a beach or in a desert. Nor can they tell the size, dimention or shape of said beach/desert.

All kidding aside, the reason I think this is because, for the past 30 years I've been interested in astronomy, there have been a good five or six, (can't remember exact number) declerations that "...we've found the edge of the universe..." or similar pronouncement. Then, some years later, there is another announcement.

Between times, there are little scuffles about it being bigger or smaller, the shape, density. Then somebody will publish a "Hubble Deep Field" equivelent image and all of the feathers would get blown in the air yet again.

I've got five bucks says in five or six years from now there will be another deep field from some scope or another proving the universe is bigger/smaller/denser/less dense/accelerating/decellerating/etc./etc./etc.




(edit to add a joke and delete typos)

[DoktorGreg]

Does this mean that the universe expanded faster than the speed of light?

[/quote]

If this is correct, and I doubt it is, (we cant even figure out with certanty the distance to globular clusters) it is a relic of inflation.

http://en.wikipedia.org/wiki/Cosmology/Inflation

[Donnie B.]

... for the past 30 years I've been interested in astronomy, there have been a good five or six, (can't remember exact number) declerations that "...we've found the edge of the universe..." or similar pronouncement. Then, some years later, there is another announcement.

Huh? Can you document this? I can recall a number of announcements that were along the lines of "This object is the most distant galaxy (quasar, cluster, etc.) observed to date", or similar. That does not equate to a claim that "we've found the edge of the universe" -- a phrase which I can't imagine any professional astronomer using in any formal way.

Now, I grant you that popular news accounts of astronomical papers may toss out such expressions as "edge of the universe", but cosmologists can hardly be held responsible for that.

As to your general conclusion, of course our understanding of the universe will improve as our observations improve. That's how science works -- and cosmology is still a very young science.

[Russ]

snip
Huh? Can you document this? I can recall a number of announcements that were along the lines of "This object is the most distant galaxy (quasar, cluster, etc.) observed to date", or similar. That does not equate to a claim that "we've found the edge of the universe" -- a phrase which I can't imagine any professional astronomer using in any formal way.

No, I can't doccument this. When my mother died I threw away all drawings, tests and other Sugar-Honey-Iced-Tea that she saved from kindergarden through college. I'm sure that whatever I read was in there somewhere. :roll:

After rummaging throug my memory, I recall, about 5th grade, a "Weekly Reader" article about a very bright light source at the edge of the universe. They were talking about a quasar but didn't call it that. Again in 7th grade a "Weekly News" article that actually said scientists claim to have found the edge of the universe. At least that is the phrase that sticks in my head.

Junior year HS, physics class we discussed a Scientific American article on how some scientists figured out that the edge of the universe was undetectable but calculated to be 20 billion, (again the number that sticks to mind) light years away.

I recall college era numbers danced around a lot between 9.? and 20.? billion. As I recall there was great difficulty callibrating redshift to distance. Actually, I think that is still the case. :-?

Now, I grant you that popular news accounts of astronomical papers may toss out such expressions as "edge of the universe", but cosmologists can hardly be held responsible for that.

As to your general conclusion, of course our understanding of the universe will improve as our observations improve. That's how science works -- and cosmology is still a very young science.

I'll grant you that some of it was news media sensation mongering but some was scientists doing the same. :roll: Kinda like the guys touting the ALH00821 (or whatever) meteorite as containing signs of life. They may have been right, they may have been wrong, but whichever, they were making a big splash. 8)

[bacterium-in-spaceship]

Does this mean that the universe expanded faster than the speed of light?

If this is correct, and I doubt it is, (we cant even figure out with certanty the distance to globular clusters) it is a relic of inflation.

http://en.wikipedia.org/wiki/Cosmology/Inflation

There are galaxies in the universe moving apart faster than light, with or without inflation. The speed limit of c doesn't apply here: it's general rather than special relativity, and on cosmological scales weird things happen to the notions of "distance" and "time".

See also:

http://www.astro.ucla.edu/~wright/co...y_faq.html#FTL

[bacterium-in-spaceship]

And, yes, this article commits the usual screw-up of confusing the universe and the observable universe.