Dumb question

rickychuck · Sep 14, 2005

Hi all, Thanks for the responses. Time dilation...hmmm...i had thought of that but had dismissed it since I thought time dilation only applied to the person who was traveling at a velocity which would make it an issue. Frankly, I hadn't thought about it from the standpoint of the BB still occuring...from it's own perspective...wow, messed me up (laughing). I think my son will be able to understand the concept of some process (such as a star forming) creating light for x number of years, therefore that light would stream outward for those x years, but would travel for x years PLUS how many "years" had passed since the moment the last light beam brought up the rear from the process that stopped making the light, to 'now', when we begin seeing it. OK, I just made myself woozy <img src="/images/icons/smile.gif" />. I find myself fascinated by this time dilation suggestion...tell me if this is what you meant...from its (the BB) perspective, it could still be occurring, (although I thought the speed estimates of what happened during the first few moments of it decreased from light speed pretty rapidly?...), but since it is happening at relativistic speeds, then while the ejecta and subsequent evolution of the matter in the universe has gone on in a measurable manner, the BB process has slowed down relative to our measurement of time passage? I fear there are major gaps in my explanation here, though...doesn't time dilation involve the crossing of distance by something as well as the measurement of time in proximity to that "something" and its comparison to the measurement of time at some other point? Egads...thud. I think I will quit asking questions and begin reading more theory to see if there are answers for all this stuff instead of nattering on. Sorry if I appear to be using up too much air <img src="/images/icons/smile.gif" />...it's a break from corporate life.

Saiph · Sep 14, 2005

Other way around. The Cosmic Microwave Background Radiation (CMBR), what we see of the BB, is the edge of our perception, at a point where it is receeding from us very, very quickly. The light is of a spectrum called a "black body", or an object emitting only thermal radiation. The shape of the spectrum tells us about the temperature of the body. if it peaks in the blue, it's ~20,000 degrees kelvin. If it peaks in the yellow it's ~6,000 degrees, in the red its ~3,000 degrees. This is the same reason why iron changes color when heated (and why people give of IR light). The big bang was HOT, millions of degrees. The stuff that emited the CMBR was millions of degrees, and so we should see a black body curve that peaks in the extreme gamma rays...if there is no time dilation. However, there is so much redshifting, due to the expansion of the universe, that we observe this spectrum not to be in the high gamma rays, but the really mild microwaves (down below IR). A redshift of this magnitude entails a very large time dilation, from our perspective. So for us, this event is still occuring, way, way, way out there. From the perspective of the emitting material, it's been done for quite some time. Now, to be fair, I'm not sure about the time dilation explaination (though it is valid for areas of extreme time dilation, like near a black holes event horizon. Here's another one (most likely correct in this case): The Big bang happened everywhere in the universe. It wasn't a "central" explosion and our planet and galaxy is a piece of debri. As such, our region of space also had the stuff that created the CMBR. It is, however, 13 billion years in the past, and long gone. that light has already reached us, and left. however, the light from the portion of the universe light years away took years to get here. we are now seeing the portion of the galaxy 13 billion light years away, finish it's thing. Ea <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

newtonian · Sep 14, 2005

rodrunner79 - Furtrhest object we see is about 15 billion light years away, which is also about the age of the universe. The Hubble deep field photo sheds light on this - it could be taken as evidence our universe's most distant objects are far beyond what we can see. If that is the case, then expansion must have been faster than light (FTL) - as in inflation theory models. As another already posted, our view is unique to us. More technically, each location has its own light cone = visibility horizon. 8 billion years to the right would indeed have its light cone 8 billion years further to the right - if indeed the universe's edge extends that far. BTW - which way is right? Would that be north?

rickychuck · Sep 14, 2005

Yoiks, forgot about the CMBR, though the instant you mentioned I recalled what little I had gleaned. Your theory about an SB (SimulBang) <img src="/images/icons/smile.gif" />, is very interesting, but would it greatly multiply the difficulty in explaining how all matter seems to be receding from a central point, and not from any other point one can imagine, never mind that it seems to be accelerating? It certainly makes for lots of frantic thought, though. For instance, from a gravitational point of view, it might explain how galaxies formed so early into the process after the primary occurrence, if it was an SB...newly formed particles colliding, randomly, yet fed from all sides, clumping together everywhere at approximately the same "time" as the fundamental force of gravity manifests itself...but yet, would this run counter to the idea of younger/older galaxies, if all galaxies began forming about the same time? I grok wrongness, dangit. On the other hand, this doesn't really explain (yet) the reason galaxies sweep along in their orbits...but maybe it does, since gravity affects everything, even across unimaginable distances. I love this place <img src="/images/icons/smile.gif" />. I am swiftly learning how little I know, and how much I want to know! (goes back to reading Understanding Physics by Isaac Asimov...hey, i'll get to the astronomy books, I swear) I really wonder what impetus was effected to cause a switching, or exposure, of an omnipresent "antinothing" to the omnipresent "nothing" which was...er...not there, in the "moment" before the whole hootenanny started? OK, I just hurt myself...time to ease my mind by building a spreadsheet (rolls eyes). Thanks for the info, guys.

Saiph · Sep 14, 2005

The "SimulBang" as you put it, isn't my theory, it's the standard explaination. Here's the thing, everything is receeding from us, uniformly, in every direction. This is exactly what you would observe, if we, earth, were the exact center of the universe (or really, really, close to it, like the milky way is the center). This implies one of two things: A) we are in a special location, a specific and special frame of reference. Or B) everyplace can consider itself the center. A is likely wrong for two reasons. First, why us? why here? and not the far more likely answer of someplace else. It's far more likely that the center of the universe, if there is one, should be billions of light years from us. Second, having a special frame of reference flies in the face of General Relativity, which requires no special frame, and says everything works out just fine without one (it even implies that there are no special frames). Now, how can you have an expanding universe, where everything is in the center? I'll give you an example to help visualize how you can have something expand, but in such a way that everything is receeding from everything else: Raisen bread. Not only is it tasty, it's educational. Look at a specific raisen in the uncooked dough. It's next to others of course. Now what happens when you bake it? The dough expands, and carries the raisens with it, stuck in the dough. The raisens all get further away from the raisen you are observing, even if it isn't in the middle of the loaf. As a matter of fact, no matter which raisen you observe, all the raisens will appear to receed from it. The distance between all raisens increases. Each raisen will see all raisens, in all directions, receed from it, exactly mimicing the conditions you would observe if you were the exact center of a spherical explosion. Yet, none of them have to be the center. This also mimics another part of the expanding u <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

newtonian · Sep 15, 2005

RickyChuck - Saiph has noted some standard explanations, notably the balloon model. My favorite model is summed up as follows: Isaiah 40:22 There is One who is dwelling above the circle of the earth, the dwellers in which are as grasshoppers, the One who is stretching out the heavens just as a fine gauze, who spreads them out like a tent in which to dwell The point I will emphasize in this post is that our universe, the heavens, is being stretched out like a fine gauze. This is different from the balloon model. In the balloon model, as Saiph notes, there is no edge and no center at tbis time. However, the stretching fabric of space model, with its threads and filaments, leaves open the possibility of an edge, or a limit, to the present expansion at this point in time. The Biblical model is in harmony with current observations, as this universe does indeed have expanding threads and filaments and does have a gauze like appearance and structure. One might expect that if God is stretching out our universe, that He might use a form(s) of energy which we are not aware of. Certainly, dark energy fits this model very well. Genesis 1:1 clearly states the heavens have a beginning. This, as Saiph notes, would be a center with time as the 4th dimension. To really fully understand the shape of our universe, we must first determine how many dimensions are an integral part of our universe - see String theories, such as the 10 dimension model and the 11 dimension model. There is much more, but I do not wish to boggle your mind. To sum up: our universe is expanding. It is close to omega=1. That is. it is close the the critical expansion rate that divides an eternally expanding universe from an ultimately collapsing universe. It will eternally expand, but because of that fine tuned rate, some sections are indeed contracting such as our local section (act

rodrunner79 · Sep 15, 2005

Wow, I feel light-headed now from reading all you guys replies and trying to understand to make sense of it all. Guess it will take a lot more reading. I just wanted to point out that this is a very good forum and it's ashame I didn't find it sooner. I used to waste my time in chat rooms and other non-astronomy related forums until I started reading bout stars, then I found this forum. I've always been fascinated by the cosmos since I was a kid. Just wanted to say thanks to everyone, I really enjoy this place, so much to learn.

rodrunner79 · Sep 15, 2005

Sorry, just wondering and imagining.... A friend of mine told me that if there was a Giant Mirror object half-a-light-year away from Earth. And we look through our telescopes and see it. We will see what's happening 6 months ago here on Earth. Is this true?

rickychuck · Sep 15, 2005

Thanks for the fine illustrations, all. I did know about the raisin analogy, although the part about a raisin twice the distance from a spot as another raisin, moving twice as far during a time of constant acceleration because it was farther away to begin with has me puzzled, and I want to do an experiment to verify that. My mind really doesn't get boggled at all this, but it does become sad sometimes that it will not be able to hang around to find the answers to all of these wondrous questions. With regard to the Giant mirror, question...let's see...half a light year is how far light from our planet will travel in six months, so if you look at the mirror six months from the moment the light is considered to be reflected off the earth, it will just have gotten to that point by then, and will still need to make the six month trip back to your eyes, assuming it bounces straight back, right? So if you assume there was no light before the start of the six month journey, you should not be able to see anything, correct? That's my story, not sure I'm gonna stick to it, though <img src="/images/icons/smile.gif" /> Or, to put it another way, what the guy above me just said before I submitted my post <img src="/images/icons/wink.gif" />

Saiph · Sep 15, 2005

the easiest way to confirm the speed and distance thing "experimentally" is to use a large rubber band, and a ruler. Cut the rubber band, so it's just a strip. Put your dots on them one inch apart. Then, stretch the rubber band, and measure the distance the dots shifted (from a "reference dot"). Check this against measurements based on a different dot. Remember to compare the "closest" and "furthest" dots from your reference point, and not "dot 1 vs dot 2" that are prelabled. Because dot 2 may be the furthest from your reference dot, and will move differently that the "closest" dot, which may be labeled differently. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

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