Sidian

red shifted means what? sorry =(

also can we see 13 billion lightyears in all directions?

what's keeping us from seeing 14 billion lightyears away? bad equipment i hope...it hurts my brain to think of any other reasons

if we can't see further because there is no light to be seen further, it would be reasonable to assume that what we are seeing is what was the edge of the universe 13 billion years ago...right?

Shadowy Man

Due to the expansion of the universe, light from distant objects gets its wavelength increased (i.e. redshifted). The farther away something is, the more redshifted the light from it.

We can't see beyond the time of last scattering, not because there wasn't any light before that, but because the universe was optically thick to radiation before then. That is, the light couldn't travel very far before being absorbed again. It would be like trying to see inside the sun - there is certainly stuff below the "surface" but we can't see it directly.

joedad

"Nothing" to me is a concept like "Nowhere." In a very classical sense, which is pretty comforting, I can find somewhere and something everywhere. When everywhere and everything start arriving from nowhere and nothing, I conclude that I am simply ignorant, or at least damn provincial in my thinking.

joe

Philosoft

Ok. What or whom do the "great majority of atheists" invoke to be able to understand the universe?

*shrug*
Speak for yourself. Consolation, comfort and safety are often boring.

tronvillain

The question "What happened before the Big Bang?" may or may not be meaningful. At the moment I take the position that it is not, for the simple reason that there is not such thing as "before the Big Bang" but I am open to evidence that there is.

Willy Wonka:
No, it is not. I deny that there is anything to be explained as nothing did not become something. There never was nothing. There is no such thing as "before the Big Bang."

Hawkingfan

Xisuthros,
I said the article "sounds ignorant to me" because the person quoted it as saying that it is silly to ask the question of what happened after the big bang. In my reasonable OPINION, in the realm of science, it is NEVER silly to ask ANY questions. Since I have not read the article, I said it "sounds" ignorant. Maybe it's not. It's just my opinion. Please don't be offended.
And X is true because of scientific hypothesis, confirmation by observation and mathematical calculations.

Oxymoron

Great smiley!

Meaning...?


Some of us still are, apparently

Seriously, though. Are you really suggesting that we really ought to be able to answer every question given our current physics and maths? How do you (or could you) know? And at what point in time did this state come about?

Excuse my ignorance: cand** : candle? By all means feel free to insult me, but at least have the decency (if that's the right word) to do so properly. (And leave my candle out of it )

DNAunion

DNAunion: Visible light is only a small sliver of the electromagnetic spectrum. In that region, light goes in the following order: red, orange, yellow, green, blue, indigo, and violet ("Roy G. Biv"). The color of light depends upon the wavelength - in the above, red is the longest wavelength and violet is the shortest. (Note that electromagnetic waves are there on both sides of visible light: infrared radiation and radio waves are longer than red light; and ultraviolet, X-rays, and gamma rays are shorter than violet).

So a red-shift means that the wavelength has increased. One of the main reasons this happens to light we detect from outer space is the expansion of space. Space expands at a constant rate on large scales (such as between galaxy clusters). So the further away a galaxy is, the more intervening space there is, and the more expansion has occurred between them and us. Expanding space stretches the light waves, thus increasing their wavelength - i.e., redshifts it.

DNAunion: Light travel time.

Each point in space (such as us here on Earth) has a Hubble sphere that surrounds it. Roughly speaking, a Hubble sphere has a diameter in light years equal to the age of the Universe. So if the Universe is 14 billion years old, we could theoretically see in any direction a distance of 14 billion light years.

But that does not mean there is nothing past that boundary. The Universe is thought to be much larger than that which we can observer: much larger than our own Hubble sphere. In fact, if our Hubble sphere did define the boundary of the Universe, then we WOULD be at the center (we alone).

So suppose there is a point in the Universe that is 20 billion light years away from us. Light has been travelling from that point towards us for only 14 billion years - it still has 6 billion more years before it could reach us.

So it is light travel time that limits us to seeing up to a distance of only 14 billion lightyears (or 15 billion lightyears, or whatever).

DNAunion: The Universe doesn't have an edge. What would happen if you were at the edge and threw a stone towards the outside? Would it bounce back off a membrane of some sort? If so, what is this Universe-enclosing membrane made of? If it didn't bounce back, would it go outside? If it did, what would it go into? Space? Well, if there's space outside the edge, then it can't be the edge of space.

[ November 14, 2002: Message edited by: DNAunion ]</p>

Jeremy Pallant

[MODERATOR]

Actually I'd rather insults be kept out of it.

[/MODERATOR]

Sidian

DNAunion thanks sir!
<img src="graemlins/notworthy.gif" border="0" alt="[Not Worthy]" />

more/new questions from what u said =)

if it takes light 13 billion years to get here, how are we here ahead of light? assuming that light and mass were together at the birth of the universe 13 billion years ago, how did we get to our place in the universe ahead of the light we're just now able to see?

is there other serious universe origin theories besides big bang?

i hadn't thought of that yet, this makes sense to me though. it's not logical for there to be an end to universe. i think maybe i would have an easier time imagining an infinite universe or a universe that somehow wrapped around on itself...though i have no idea how that could work. nothing even comes to mind that would explain an "edge to space"

i don't understand what u mean here. if there ever was truly nothingness, that would seem like perfect stability. there would be no forces, energies, gravities, or motions, or anything to obstuct that perfect stability either. i would say that our existence is proof that there never was nothingness or else there would have been no way to have left nothingness and we would not be.