Recent content by zadignose

Hmmm... someone may need to provide a link or information about jargon then, because even your earlier post got me to reconsider the use of the word "closed," but it wasn't so clear to me that I must also reconsider "critical density." What is the meaning of "critical density," and why is it...

I hope that this will be a simple question, but I had difficulty finding an answer by searching. If the Cosmic Microwave Background radiation was radiated over 13 billion years ago, and we are able to see it now, then does this mean that the radius of the universe at that time must have been...

Okay, I understand what you're saying about jargon, except I'm picking up the language as I go, and folks in these threads and other sources seem to use the terms in various ways. New revision: -The number of observable galaxies is increasing, but will not necessarily always do so. -If the...

If what I said immediately above is true--and it seems to be--then my questions in message #11 have been answered (my assertions were false). I'd have to revise as: -The number of observable galaxies is increasing, but will not necessarily always do so. If the universe is "open" eventually some...

@Marcus: If I understand you, then what you've said suggests that the observable region has to grow... and then shrink again! Check if this is right. A galaxy which is currently 62.75 Gly away will eventually become observable, because light (or neutrinos, or...) that was emitted from that...

Okay. For such a time as the entire universe is not yet observable (because we have not yet received radiation from the most distant objects) Is it correct to say: -The number of observable galaxies will always be increasing, regardless of whether the universe is open, flat, or closed, and...

Okay, this is all helpful, thanks everyone. Let me pause and do a summary, which may not include everything, but is what I've gathered so far: -If the universe is "open" then it will expand without limit. -We still can't draw any definite conclusions about what may exist beyond the limits of...

I will return to your link and read it in detail ASAP, but meanwhile, while I thought I understood the balloon analogy, I also thought that finite and unbound only made sense in a closed model of the universe. Can there be an "open" universe which contains a finite amount of matter and energy...

Okay. So far there's a bit of disagreement among responses, but it seems that not all physicists agree that an "open" low-density universe indicates an infinite expanse of matter and energy beyond the observable universe. What is agreed upon is that, in such a model, the observable universe can...

I know some folks may get tired of questions about the finite/infinite scope of the universe. Sorry for that. But as you know, many concepts are hard to wrap one's head around. Let me make my question as clear as possible from the outset: -I am NOT asking whether the universe is infinite or...

Thanks folks, this makes sense.

I'm having trouble resolving the contradiction between theories of the Cosmic Microwave Background, and Special Relativity. Einstein denied the existence of any absolute standard of rest. As einstein-online.info paraphrases: "In the real world, there exists no such state of absolute rest...

In Cosmos, Sagan explains to us laymen that stars fuse hydrogen into helium, and then if a star is big enough it creates higher order elements in later stages, before going supernova. What isn't explained is why such a high proportion of heavier elements (heavy relative to hydrogen) collect to...

"You can't fit a three dimensional object in a two dimensional box" : obvious fact. "A three dimensional object can't exhibit itself within a two dimensional area" : obviously wrong. The essay that opened this thread seems like more a play on words than a logical argument or proof of anything...

I'm not objecting or anything, but seeking to learn. What's the evidence/proof that the milky way is not the center of the universe?