Expanding Universe

[bechcube]

Are there adequate hydrogen clouds in space(Egale Nebula star creation field) to form adequate new stars, which, when forming a galaxy, would replace those galaxies lost through the expansion acceleration of the universe?

 

[Saiph]

...nope. It'll get pretty spread out, and fewer stars will be born, as the universe ages. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"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" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[bechcube]

Does everyone having knowledge agree with Saiph that since each galaxy has many star formation fields which congeal to form galaxies, that such galaxy creation is not adequate to keep the universe static?

 

[petepan]

<font color="yellow">Does everyone having knowledge agree with Saiph that since each galaxy has many star formation fields which congeal to form galaxies, that such galaxy creation is not adequate to keep the universe static?</font><br /><br />I agree with Saiph. I was under the impression that the 'new' star forming regions, in a galaxy, will not go off to form a new galaxy, but rather become part of the galaxy itself. Also, the galaxy would tend to remain fairly static, IMO, as you have to remember that other stars are also dying in the same galaxy, so unless birth of new stars is out stripping the dying stars, it should be fairly static.

 

[bechcube]

Back to you Saiph:<br />You have agreement from Peterpan but my question is still unanswered.<br />Although I believe it is possible for large numbers of star formation in a confined area to rotate about a common center of gravity and for that group to exit its hoast galaxy, I was asking about star,hense galaxy,formation in space unattached to any galaxy, star cluster or galaxy cluster.

 

[Saiph]

From what I recall, surveys across large ranges in redshift (thus distance, thus time) shows a decreasing amount of galaxy formation and activity, along with a peak in star formation "universe wide" several billion years ago (I'm thinking around 7, though I don't remember an actual number).<br /><br />As such, the trend is obviously agianst it.<br /><br />Dwarf galaxies may form, but major galaxy formation is, as our observations seem to indicate...deminishing. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"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" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[rickstine]

Just like Saiph I to think you are just going to get a small galixy with less stars than are own that could possible be a sprile galixy, but it depends the amount of gravity forced upon the galixy so it could turn out to be a wirlepool as far as I know,but the amont of gas and gravity do play some part into this.

 

[majornature]

It is believed that "Dark Matter" is causing the expansion and cooling of the universe. Soon the stars and the galaxy we see will be no more, it will be total darkness.<br /><br />Searching for the truth!!! <div class="Discussion_UserSignature"> <font size="2" color="#14ea50"><strong><font size="1">We are born.  We live.  We experiment.  We rot.  We die.  and the whole process starts all over again!  Imagine That!</font><br /><br /><br /><img id="6e5c6b4c-0657-47dd-9476-1fbb47938264" style="width:176px;height:247px" src="http://sitelife.space.com/ver1.0/Content/images/store/14/4/6e5c6b4c-0657-47dd-9476-1fbb47938264.Large.jpg" alt="blog post photo" width="276" height="440" /><br /></strong></font> </div>

 

[kmarinas86]

<font color="yellow">It is believed that "Dark Matter" is causing the expansion and cooling of the universe. Soon the stars and the galaxy we see will be no more, it will be total darkness.</font><br /><br />It's not Datter Matter, but Dark Energy that is believed to be causing this. Dark Matter is necessary in some theories because the speed of certain galaxies and stars are so fast, but they stay togther. Essentially, the existence of extra matter that we don't see is said to be responsible for velocties of stars at the edges of galaxies and galaxies of galaxy clusters. Dark Energy is for explaining the perceived acceleration of expansion.

 

[nexium]

There are other opinions besides Saiph, but they are in the minority. Most galaxies formed more than 5 billion years ago. Recent galaxy formation is rare. New stars are being formed in most galaxies at a decreasing rate, so the night sky is darkening in more places than it is brightening thoughout the visable Universe, due to the accellerating expansion and brighter stars ending main sequence. Average brightness may be down by half in as little as three billion years. Neil

 

[ihwip]

I have one question on this expanding universe thing.<br /><br />If we observe an object 14 billion lyrs away it seems to be going away faster than an object 7 billion lyrs away.<br /><br />Why do scientists believe this is evidence that the universe's expansion is accelerating? The light from the distant object is 14 billion years old. That means that it was moving away faster 14 billion years ago. The closer object's light is younger and moving slower.<br /><br />What is to say that the distant object is going the same speed as the closer object in real time and the only reason it appears to be going faster is because of the time lag? Maybe our view of it appears faster 'cause it is coming from an older, more rapidly expanding universe.

 

[CalliArcale]

I'm not a physicist, nor do I understand this fully, but as I understand it, the problem is that the observations don't match up with what would be expected unless the expansion is accelerating. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[lukman]

I had the same question, i posted the same question before, there was an answer, quite logic, but not a satisfying answer, true, the further we see, the older the time. Fast expansion during early time is not a surprise, since it was still at a very high energy big bang. <div class="Discussion_UserSignature"> </div>

 

[SpeedFreek]

Well the problem is that people are mixing up different observations here.<br /><br />The observation that the further things are, the faster they are receding, only tells us that the universe is expanding. Even with a constant rate of expansion, the further things are, the faster they recede. The relationship between distance and speed of recession is actually pretty linear until we look at the most distant objects themselves. At those furthest distances (looking back to earlier times), the redshift of objects increases dramatically.<br /><br />This gives us a picture of an expansion that was very fast early in the universes history, and the rate of expansion has been slowing down since then. When plotted on a graph, looking back in time, the rate of expansion is a long, almost straight line that curves sharply upwards as we approach the big-bang.<br /><br />The problem comes when we try to estimate what the expansion rate has been doing relatively recently. Our redshift observations cannot tell us that, because those closer objects are gravitationally bound to our local cluster of galaxies and so their redshifts are dominated by their inertial movement relative to us. Andromeda, for instance, is moving towards us. Only objects outside our local gravitationally bound group of galaxies will be receding due to the expansion of space and they are all a few billion light years away, at least.<br /><br />So up till recently we had no clue what the expansion had been doing for the last few billion years or so, and had to assume it was still slowing down.<br /><br />But then we started observing certain kind of supernovae, known as type 1a, which seem to always have an identical magnitude, and thus came to be known as "cosmic candles", a useful tool for "calibrating" our observations.<br /><br />The problem is, the <b>closer</b> type1a supernovae seem to be dimmer than they should be, for their distance (which we infer from any nearby galaxies they seem to be interacting with), when <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[primordial]

IHWIP! Could the Red shift be a result of the density ratio due to the emmision of radiation that propagates space-time at the velocity of light, and that of mass, that can only aproach the velocity of light . If space-time expands at the rate of C and light propagates at C then the outer expanse of space-time could contain the Energy, including the CMB radiation that has escaped obsorbtion by mass. If this is true it could be the smoking gun for Dark Energy, and account for the missing Mass. Just think about it.

 

[SpeedFreek]

Err..... <br /><br />Well, what do you mean by space-time expands at the speed of light?<br /><br />Objects with a redshift of z=1.5 are considered to be receding from us at the speed of light, due to the expansion of space. We observe objects with redshifts of z=10, indicating that they are receding at multiples of the speed of light, but arent violating any laws since they are not receding due to inertial movement, but due to the space in between them and us expanding. The CMB has a redshift of z=1089!!<br /><br />So what do you mean by "space-time expands at the rate of C"? The parts of the universe that seem to be receding at the speed of light are less than 10 billion light years away, with everything that is more distant than that apparently receding at superluminal speeds. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[primordial]

Mr. Speedfreek! How then is it possible to observe any thing that travels faster than light? Given the equation f=f' [(1+v/c)/(1-v/c)]^.5 .<br />If it's moving away from the observer the frequency shifts to zero. and if it approching the frequency shifts to infinite. So you'r saying that 1.5Z= the speed of light exactly ?

 

[SpeedFreek]

The metric expansion of space means that all distances change by the same factor, over the same time.<br /><br />As an example, if it takes, say, 10 billion years for 1 meter to expand to double its size, in that same 10 billion years, all meters will double in size, so 10 billion light years would double to become 20 billion light years.<br /><br />Now then, if it took 10 billion years for 1 meter to double in size, that is a <b>very slow</b> rate of expansion at the scale of a meter. But if in the same 10 billion years, 10 billion light years becomes 20 billion light years, that is a <b>very fast</b> rate of expansion at <i>that</i> scale - that scale has expanded at the speed of light, while the meter expanded very slowly. With the same rate of expansion, anything over 10 billion light years away would be receding at a speed that was <i>apparently</i> faster than light.<br /><br />Of course, that object is <b>not</b> moving faster than light, in fact it is hardly moving at all, relatively to any other objects local to it. When the light left that object, the expansion rate locally (at the meter scale) was very slow, and the light could easily cross that space and start its journey towards us. The meters it crosses are all getting larger as it crosses them, but it has no difficulty crossing them, it just takes longer to do it. All the time the light is travelling, it is being stretched by the expansion of the space it is travelling through, and more space is being added (space is expanding) in front of it, putting its destination further away. But the light still continues to travel through that expanding space, until it finally reaches its destination.<br /><br />When we measure the most distant galaxies by size, we observe that they were only around 2 billion light years away when the light left them, but when we measure how much that light has been stretched (redshift) we infer that light took 13 billion years to reach us because it was travelling through space that wa <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[primordial]

You have a way to change space without changing time? You have the same idea as I, I think you just explain it differently. let me read your note. ok

 

[SpeedFreek]

This paper explains it all.<br /><br /> Expanding Confusion: common misconceptions of cosmological horizons and the superluminal expansion of the Universe <br /><br />This is from the conclusion:<br /><br /><i>"We have clarified some common misconceptions surrounding the expansion of the universe,<br />and shown with numerous references how misleading statements manifest themselves<br />in the literature. Superluminal recession is a feature of all expanding cosmological<br />models that are homogeneous and isotropic and therefore obey Hubble’s law.<br />This does not contradict special relativity because the superluminal motion does not<br />occur in any observer’s inertial frame. All observers measure light locally to be travelling<br />at c and nothing ever overtakes a photon. Inflation is often called “superluminal<br />recession†but even during inflation objects with D < c/H recede subluminally while<br />objects with D /> c/H recede superluminally. Precisely the same relationship holds<br />for non-inflationary expansion. We showed that the Hubble sphere is not a horizon —<br />we routinely observe galaxies that have, and always have had, superluminal recession<br />velocities. All galaxies at redshifts greater than z ~ 1.46 today are receding superluminally<br />in the lambda-CDM concordance model."</i><br /><br />All I am doing in my posts is trying to put the concepts of the current Lambda-CDM concordance model into simpler terms <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[primordial]

Speedfreek! Your have a valid argument. One way out of this problem is to make a precession measurement of the rate we( our local cluster) propagate through the Cosmic Background Radiation and determine our increase in acceleration relative to it, because we are the only observed thing in the present.

 

[SpeedFreek]

But, and this is <i>central</i> to the issue, our local cluster of gravity-bound galaxies is considered to be at rest, relative to the expansion of space! The gravity-bound cluster moves inertially only within itself, and the space outside it expands, increasing the distance to the next gravity bound cluster.<br /><br />The effect of expansion on radiation/light is that of stretching it. The effect is cumulative, as the radiation is being stretched all the time it is travelling through expanding space. The CMBR was emitted over 13 billion years ago, and the redshift shows this cumulative effect.<br /><br />We cannot consider our local gravity bound cluster to be moving <i>through</i> the cosmic background radiation. An object moving inertially within the cluster can be considered to be moving through the radiation, but if it were possible to compare its motion to that of the radiation it was moving through, it would only be measuring <b>inertial</b> motion, caused by gravitational attraction to other objects within the system.<br /><br />The gravity bound cluster is not moving <i>through</i> the radiation, but rather the radiation is all being stretched away from the cluster, by the expansion of the space that the radiation resides within. To know the current expansion rate, all we can do is look at objects outside our local cluster - we are looking billions of light years away before we can be confident that expansion is the primary cause of redshift. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[primordial]

Mr. Speedfreek ! I understand what you are saying it's almost like the density of the universe is becoming less with time passing thus reducing the ambient gravity of the present universe so as to have time in the present to run faster than the time in the past for which would give a red shift of past events. If a way exists that could reduce the mass of the universe with time, or divert the gravitational interaction into one of the other interactions, or as some astrophysicist have proposed gravity leaking out of the Universe.

 

[primordial]

ranur! Where did you get that info.. I have never heard of it.

 

[R1]

clocks tick slower the stronger the gravitational field they're in, so if the the universe is becoming less<br />dense then the density of clocks ticking slower is becoming less<br /><br /><br />IHWIP, here's a post and discussion on the expansion:<br /><br /> http://uplink.space.com/showthreaded.php?Cat=&Board=sciastro&Number=663895&page=&view=&sb=&o=&vc=1<br /> <div class="Discussion_UserSignature"> </div>