What I don't understand about the Big Bang Theory

willpittenger · Sep 6, 2007

The farther away you look, the older things get. So if you look far enough, you should see the Big Bang itself, right? Wouldn't you be at that location? Furthermore, you would get that result looking in any direction. What did I miss? <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

dragon04 · Sep 6, 2007

You're forgetting that after the big bang, and as mass became less dense and more scattered, the Universe went "dark" for a time before matter began to clump again and start to form stars and galaxies. The most distant objects we've recently detected are theorized to be evidence of the "clumping" the led to the Universe "lighting back up". IOW, we're seeing an effect that's separated in time from the original event. During the "dark phase", the Universe was still expanding. Expanding without visible evidence. <div class="Discussion_UserSignature"> "2012.. Year of the Dragon!! Get on the Dragon Wagon!". </div>

dragon04 · Sep 7, 2007

So in the early universe matter was dark literally, and then suddenly became "visible" .. Now how do you suppose that happened, and, where's all this other matter? I explained that in my response, but...... <img src="/images/icons/wink.gif" /> Read this. Gives a great timeline. All space, time, and energy began with the Big Bang. As the universe cooled, energy turned into matter. Quarks and electrons, then protons and neutrons appeared in the first minute. But at temperatures of 1 billion degrees, it was too hot for complete atoms to form. Scientists have found that it took another 300,000 years for the temperature to cool off enough for whole atoms of hydrogen to appear. The half billion years between the formation of these first atoms and the creation of the most distant light-emitting objects detected by astronomers remains shrouded in mystery. Astronomers have dubbed this period the cosmic Dark Ages. My emphasis... Explains is better than I can <div class="Discussion_UserSignature"> "2012.. Year of the Dragon!! Get on the Dragon Wagon!". </div>

docm · Sep 7, 2007

This might help you visualize it. The blotchy green area to the left is the pattern seen in the cosmic microwave background (CMB). <div class="Discussion_UserSignature"> </div>

weeman · Sep 7, 2007

The farther away you look, the older things get. So if you look far enough, you should see the Big Bang itself, right? Wouldn't you be at that location? Furthermore, you would get that result looking in any direction. What did I miss? The furthest back in time we should theoretically be able to see is when the universe became 'transparent', some 380,000 years after the initial BB. This is when the universe cooled enough so that photons were able to escape the primordial plasma. Take our Sun as an example. Photons that are generated at the Sun's core don't necessarily make their way straight to the surface. They ricochet and bounce off of other subatomic particles, causing their trip to the surface to take many, many detours. This is in some ways similar to the early universe. Due to the thick "fog" or "plasma" that existed within the first few hundred thousand years of the universe, photons could not escape to begin their journey through space. So, the word 'transparent' might not have its literal meaning in this situation, but it is the time when the universe came out of its "dark age". You are correct, if we could see the big bang, we would see it in every direction in the sky, since we exist at the center of our own observable universe. This is why we see galaxies getting older and older the farther we look, no matter which direction we look into space. <div class="Discussion_UserSignature"> Techies: We do it in the dark. "Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity." -Albert Einstein </div>

dragon04 · Sep 7, 2007

So to postulate that ordinary visible matter came into being from some unknown dark matter, and that this unknown dark matter might actually still exist is not so far off the mark? Hmm ..How do you suppose it is interacting with ordinary matter today? It is the ordinary matter of today. <img src="/images/icons/smile.gif" /> It's not "unknown dark matter", IOW. We're talking about the original atoms that formed when the universe cooled down enough to allow subatomic particles to couple and form atoms. Before the universe was "turned on" how dense would you expect it to be, and would it be necessarily uniform? Can't answer that one precisely. Don't know enough. <img src="/images/icons/wink.gif" /> BUT, I can tell you that matter density in the Universe was not dense enough to allow for nuclear fusion at that time. And I can tell you that matter must have expanded less and less uniformly over time, otherwise, clouds of hydrogen could never have condensed into the first stars and galaxies. I assume that gravitational interactions took over, and that because the primordial hydrogen clouds had differing masses, the uniformity kept decreasing. <div class="Discussion_UserSignature"> "2012.. Year of the Dragon!! Get on the Dragon Wagon!". </div>

dragon04 · Sep 7, 2007

Explain your "static model"? <div class="Discussion_UserSignature"> "2012.. Year of the Dragon!! Get on the Dragon Wagon!". </div>

vogon13 · Sep 7, 2007

WIK,TYDK,WSAM. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

nexium · Sep 7, 2007

Hi vogon: Do those abreviations have meaning? Neil

dragon04 · Sep 7, 2007

It's almost insulting that you guys keep throwing examples and instruction on what the BB is, as if to assume that I am trying to question it, without doing some research .. Nobody intends insult. I certainly don't. We're telling you why we think we're correct, and you're not and providing what hard science there is to back up what we're saying. You're free to make up any theory you want. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> "2012.. Year of the Dragon!! Get on the Dragon Wagon!". </div>

SpeedFreek · Sep 7, 2007

Hicup is correct in that the CMB doesn't prove the big-bang happened. Big-bang theory predicted the CMB, and then the CMB was discovered. If they hadn't found the CMB, then the big-bang theory would have faltered, but they did, which simply means the theory is still a valid model... The steady-state theory could also be valid, if we can find another means to explain correlation between redshift and distance at the larger scales, or if we find we are misinterpreting what the redshift signifies. <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

brellis · Sep 7, 2007

The steady-state theory could also be valid, if we can find another means to explain correlation between redshift and distance at the larger scales, or if we find we are misinterpreting what the redshift signifies. so glad to have speedy participating in this thread! I asked in this thread if we knew the "location" of the BB. speedy offered excellent insight! <div class="Discussion_UserSignature"> I'm a recovering optimist - things could be better. </div>

jeffhannan · Sep 7, 2007

One thing I find confusing is when reports talk of the age of a galaxy. For example in this report.. http://www.space.com/scienceastronomy/070906_toy_galaxies.html the galaxy is 1 billion years old. So it has taken 12 billion years for its light to reach us - travelling 12 billion light years. But surely we weren't that far away to start with, even accounting for the expansion of the universe. By the way, I'm not a skeptic. I've read a lot about the universe, but I'm just missing something here. Jeff

willpittenger · Sep 7, 2007

I have a theory of my own that can't be proven or disproven. To explain it, I need to explain how Star Trek holodecks are supposed to work. Please refer to the image below. The stick figure is you. You are looking across the holodeck and see many apparent objects. The problem is that not all of them are real. The colored boxes are something that you could reach out and feel. If one were an apple, the computer would replace it with the real thing if you reached for so you could eat the apple. However, those too far away to represent in the limited space of the holodeck (imagine reproducing a view of the Rockies) are represented on a screen. This screen is represented by the black line. Each person sees their own version. The red line is a forcefield that acts like a tread mill. If you attempt to walk towards the screen, the treadmill part keeps you from getting closer. Rather, the screen changes its appearance. Eventually, it disappears. If you and someone else were looking at each other, the computer would use these screens to make it look like you were farther apart than you appear to be if needed. Now why this would be the came requires some religious faith. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

ashish27 · Sep 8, 2007

<blockquote>In reply to:<hr /> The farther away you look, the older things get. So if you look far enough, you should see the Big Bang itself, right? Wouldn't you be at that location? Furthermore, you would get that result looking in any direction. What did I miss? <hr /></blockquote> Nothing. You missed nothing. In fact you are exactly right. Yes if we look far enough we do see the Big Bang. But the problem is we can't see it through optical telescopes or more correctly we can't see it in visible light. You see the BB occured before the inflationary phase, so light from the time of the BB would be so highly redshifted that we would see it as microwaves. And thats exactly what is called the Cosmic Microwave Background. The CMB is present everywhere & equal in all directionsof space. Penzious and Wilson discovered it in 1965 and was awarded the Nobel prize. http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation

lukman · Sep 8, 2007

We cant see big bang or any earlier than our universe age, because the big bang expanding space FTL. So, we are actyually looking at observeable universe, it is hubble limit, infact there are more out side the "universe". I know it from here: universe adventure <div class="Discussion_UserSignature"> </div>

willpittenger · Sep 8, 2007

I still don't understand why the CMB would appear in any direction I look or how the matter (or whatever existed before matter) could be in both places at once. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

ashish27 · Sep 9, 2007

<blockquote>In reply to:<hr /> I still don't understand why the CMB would appear in any direction I look or how the matter (or whatever existed before matter) could be in both places at once. <hr /></blockquote> bcoz the Universe expands in all direction. So the BB occured at all points in space.

alokmohan · Sep 9, 2007

The balloon is expanding and we are on surface of it.

willpittenger · Sep 9, 2007

Neither of you make any sense. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

vogon13 · Sep 9, 2007

LOL !! <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

ashish27 · Sep 10, 2007

yup, and its so much redshifted that what once was visible light is now microwaves

a_lost_packet_ · Sep 10, 2007

wiltpittenger - I still don't understand why the CMB would appear in any direction I look or how the matter (or whatever existed before matter) could be in both places at once. There are some great illustration examples from several people. However, to put it a little differently and, probably, muddy up the waters some more: Think of the CMB as a big splash of paint that occurred shortly after the Big Bang. The Universe was covered with it. But, the Universe expanded since that time and is continuing to expand. The paint stain that is all over the early fabric of the Universe is stretching with it. As it stretches, it becomes "thinner" and less easier to notice. But it is still there, everywhere we look. By examining it, cosmologists hope to see the original picture that was created when it was first made and all the shifts and movements it has made while expanding with the fabric of the Universe. Of course, this illustration could be misleading or misinterpreted. In that case, I will defer to someone's more accurate cosmological insight. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> I put on my robe and wizard hat... </div>

weeman · Sep 10, 2007

wiltpittenger - I still don't understand why the CMB would appear in any direction I look or how the matter (or whatever existed before matter) could be in both places at once. Ashish's short response up above sounds quite accurate. I can elaborate on that. The universe began as a single point in space (and time). We can't look to a single direction in the sky and see the big bang, because the big bang happened everywhere, all at the same time. It sounds absurd, but to understand this, we must turn back time to a point when the universe was very, very small. Since it began at one point, everything that we know of as the "universe", existed within this single point. So, since everything happened within this one point, and expanded outwards, we can say that the big bang happened everywhere. At the time of the big bang, EVERYWHERE was this single point. Now I sound like I'm repeating myself <img src="/images/icons/tongue.gif" /> So, the CMB that was created at the time of the big bang was everywhere within that point. Now, since space has expanded, the CMB still exists everywhere within the point, it's just that it has expanded to a much larger size! It is as if the CMB radiation is intertwined with the metric expansion of space. Today, there is still the exact same amount of CMB radiation that there was at the time of the big bang. However, just as a_lost_packet_ explains it, it has been stretched out over billions of lightyears, so it is harder to detect. The expansion of galaxies is not galaxies hurling through open space. Rather it is the fabric of space expanding itself. So, since the CMB exists within the fabric of space, it expands along with the expansion. I hope this all makes sense <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> Techies: We do it in the dark. "Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity." -Albert Einstein </div>

SpeedFreek · Sep 11, 2007

Just to cover some details about the theory.. The CMBR was not emitted until around 400,000 after the big bang, and happened after the universe was expanding at its fastest. After the initial inflation, the expansion was extremely fast, slowing down for around 400,000 years until the CMBR was emitted. This means the observable was universe was already a very large volume of space before the universe became transparent when the CMBR was emitted. (The whole universe could have been many times larger than our observable universe at that time, but we can only know the size of our observable universe). At that time (when the CMBR was emitted as the universe finally became transparent after 400,000 years of expansion), the point in space where our galaxy would eventually form was of course at the centre of that observable volume of space. This space was filled with radiation, of slightly varying temperatures and we were in the centre of it. If you want, you can think of it as a volume of space 400,000 light years in radius, with our position in space at the centre, but the figure of 400,000 ly is arbitrary because metric expansion causes the edge of the observable volume to recede superluminally and thus the volume was already larger than that, and anyway, photons only separated and evolved independently after the CMBR, so you would have to wait another 400,000 years (at least!) to see all of it, but there was nothing to see anyway until the galaxies started to form which happened at least 100 million years later, by which time it was much larger, and so on.. but you get the idea.. <img src="/images/icons/wink.gif" /> (the size of the observable universe when the CMBR was emitted is actually theorised to be around 40 million light years in radius!) The CMBR shows the latent heat signature of that observable (by us) volume of space as it was when the CMBR was emitted, with us at the centre. <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

What I don't understand about the Big Bang Theory

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