Talk:Universe

Questions on the shape of the universe and other things

If the universe is expanding like an expanding balloon, why wouldn't the universe have all stars and galaxies on the surface of the balloon and have a big hole of empty space in it? Is there any reason for galaxies to move away from the center faster or slower? Would some matter still be at the exact location as all matter was originally placed? Like the center of a bomb that just stayed right where the bomb was placed? I e is the universe a balloon filled with stars or are they pretty much plastered along a spherical surface leaving empty space within the sphere?

You're carrying the analogy too far. The balloon analogy is only supposed to illustrate the idea that things can grow farther from each other without moving away from anything in particular. It doesn't even do a very good job of that, because people inevitably get the idea that things are expanding away from a point in the middle of the balloon, which is totally wrong. Best to just forget the analogy. There's no center of expansion of the universe. -- BenRG 17:56, 14 July 2007 (UTC)

In the case that most stuff would be at the outer edge of space: if you looked out from the balloon you wouldn't see anything for there wouldn't be anything there. But now it seems like you see equal amounts of stuff in all directions from the earth, or do you? And why in that case?

Even if all stuff did not move away from the center at the same speed since the big bang you would definitely have some objects moving in almost opposite direction from each other and some objects along each other, like the Milky Way and Andromeda, right? So light from the stuff on the opposite side of the balloon would take much longer to reach us since we're moving apart so quickly? While the Milky Way and its closest galaxies are moving apart very slowly, right?

In any way, can anybody find an illustration of what the universe might have looked like all the time to now? And how the objects and formations would be located in relation to each other? Not because anybody definitely know, but just a best guess, that would be really good.

On the age of the universe: For a person sitting on a ball that flew out from the center at big bang it would have felt like 14bn years till today? If the person had a 14bn years half-life in his own time he would have halved till today? How long would it have felt like for a person still sitting at the same place in the center of the big bang till today? Let's say the other person was moving away from him at maximum speed. Would it be 14bn years in that persons own time to? -- JR, 18:54, 19 May 2007 (UTC)

On the Hubble constant: Is it really a constant, is it not decreasing with distance? If it's about 0,022 m/s per light year (0,071 m/s per parsec) that gives a moving away speed of more than light speed at a distance of 14 billion light years. 0,022*14E9 = 308 Mm/s. Is that a problem? I saw that z factors (of red shift) of 6 have been seen. That would give a comoving distance of 19bn light years from a relation between the distance and z-factor i saw. So a good guess is that those stars are moving away at about 400 Mm/s? The distances of 45bn light years mentioned in the article, were those mesaured from red shifts? With the hubble constant they would be moving away at more than 900 Mm/s then? -- JR, 13:41, 29 May 2007 (UTC)

In theory Hubble's law applies to arbitrarily large distances (it has to, because of homogeneity). The speed exceeding c is not a problem. This is a different kind of speed from the kinematical speed in special relativity that can't exceed c. A redshift of 6 corresponds to a comoving distance of 27 billion light years, not 19, according to Ned Wright's cosmology calculator. (The relationship between redshift and comoving distance is not linear.) Multiplying by H_o gives a speed of 600 Mm/s or 2c. Distances like 45bn light years are inferred indirectly by fitting parameters of the model. Redshift is one of the most important sources of empirical data we have, so you could say that the distances are inferred from redshifts in some sense. The most distant part of the universe we can see (via the CMBR) has a comoving speed of about 3.3c. -- BenRG 17:56, 14 July 2007 (UTC)

False Analogy in 'Shape' Section

The analogy used to show that the universe may have no boundary but be finite is false-- spheres may not have an edge, but they are bounded. The universe is supposed to be unbounded, so we're looking for something to show that an unbounded space may be finite. The analogy given does not do this; it is false. I won't remove it because someone smarter would put it back up. Please consider this and remove it.

I agree. The 'Shape' section is full of false statements, unspoken assumptions, and poor wording. I threw in qualifiers ("may," "if," "conceivably"), but it still lacks rigor and clarity. I don't think anyone who is not already familiar with the concepts described would learn anything from the section. It needs to be rewritten completely. 24.27.9.13 03:52, 8 January 2007 (UTC)

Our Universe name

Why there is no name for our universe? And is the universe=everything? If universe =everything then what we call this (the 1.9 × 1033 cubic light years)

Is there is a good name for “everything”?

Now if we ever found that the space is a lot bigger then what we thank, and patterns of our universe exist in millions, shouldn’t we name our universe?!

Uh, I think it's just "The Universe." Other universes would just be "Other Universes." It's not like we really need a name for our universe, as we aren't really going to be travelling to other ones. Sorry. Citizen Premier 02:12, 25 October 2005 (UTC)

The good name for "everything" is "universe" :) Chris M. 00:09, 12 January 2006 (UTC)

This is not acceptable. Please come up with a good name. --einexile 00:41, 28 June 2007 (UTC)

What about Bob? 66.193.238.1

Contradiction

I removed the paragraph

But some of the objects outside of the observable universe can, in principle, be observed indirectly. For example, it is theoretically possible to meet an observer located near the end of our observable universe, who in his past has observed some galaxies that left our observable universe because of expansion.

I'm a mathematician not a physicist but this seems to contradict the paragraph above about Causality.

It's a poorly phrased version of the statement that things that were once in the observable universe can leave it. This hasn't actually happened in our universe, because between cosmic inflation and dark energy domination, it wasn't expanding fast enough, and we were able to observe more and more things. However, in the future, things will pass outside the event horizon, and be irretrievably lost to us. – Joke137 23:58, 17 July 2005 (UTC)

Meaning of Universe

The Universe is the whole spacetime continuum in which we find ourselves, together with all the matter and energy within it.

Different words have been used throughout history to denote "all of space", including the equivalents in various languages of "heavens", "cosmos" and "world".

For a large fraction of the twentieth century, the word Universe, with an upper case "U", was used to mean the whole spacetime continuum in which we find ourselves, together with all the matter and energy within it.

However, since the standard Big bang model has become well established observationally during the last few decades of the twentieth century, theoretical cosmologists have come up with new ideas of "the whole spacetime continuum" which are much, much larger than the "Universe" corresponding to the Big bang model. For this reason, the word universe can now be used in the plural and with a lower case "u" when discussing theories about all of space-time. There is no clear consensus on what new word to use for the whole spacetime continuum (though some like the term multiverse), and as long as there is no conceivable method of measuring anything beyond the observable horizon (formally speaking, the particle horizon), this is a seen as a moot point (irrelevant) for empirical scientists, and is of interest only to philosophy.

infinite universe?

It is not known whether the Universe is finite or infinite in spatial extent and volume, although current theories favor an infinite Universe.

although the majority of theorists presently favor an infinite Universe.

Rubbish. The majority of theorists currently favour an infinite Universe, but this is a matter of personal taste and sociology and historical fashion and nothing to do with physics.

I certainly also sense theorists favoring an infinite Universe. I disagree that it is a matter of taste.

http://www.sciam.com/article.cfm?articleID=000F1EDD-B48A-1E90-8EA5809EC5880000 "Parallel Universes" Not just a staple of science fiction, other universes are a direct implication of cosmological observations. By Max Tegmark.

NealMcB 17:46, 2004 May 4 (UTC)

That's why it's stated as "the majority" Chris M. 00:11, 12 January 2006 (UTC)

size of universe

48 billion (48 ? 109) light years.

50x10^9 light-yr = 5x 10^10 *0.3 pc = 1.7x 10^10 pc = 17 Gpc = 12 /h Gpc (where h=0.7 is the Hubble constant) OK :), this is approximately correct for Omega_m=0.3, Omega_Lambda =0.7, though 10/h Gpc is closer. In any case, i'll round to 50 since it's no more than 10% precise.

I'm glad the way this is improving - and i love the desire to avoid ambiguity. Wikipedia is definitely a good tool for spreading relatively wellunderstood information to outsiders without expecting them to waste hours and hours to sort through ambiguous jargon.

--boud

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I see various estimates of the number of particles in the observable universe, e.g. the claim in Wikipedia talk:Size comparisons that It is accepted by astrophysicists that the number of particles in the observable universe? is currently in the 10⁸⁵ range. This seems like the place to document that. Does anyone have some good references? NealMcB 18:27, 2004 May 4 (UTC)

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"...it is estimated to be about 78 billion light years (7.4 × 1023 km)."

Interesting....just based on what did this 'estimated value' came from? At least a note should be provided for this kind of 'data'. LegolasGreenleaf 11:26, Nov 7, 2004 (UTC)

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"...billion ..."

What kind of billion?, I meen, 10^9 or 10^12? I know that wikipedia uses 10^9 "if don't state otherwise" but I think that talking about science and to avoid ambiguity, is better 10^9 or the prefixes "giga" or "tera" see wikipedia, long scale alternative approaches

I agree. Jimp 09:21, 28 February 2006 (UTC)

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Is it not possible that we are concentrating on the universe as a ball instead of a balloon. Could we not be an outer layer petering out and as for the big bang it is very much like the opposite of the current theory involving black holes, so theoretically could not ours have started from a black hole reaching a set limit then exploding outwards. Baloons inside balloons. So size isn't what is worrying, it's rate of decreasing depth? Based on Sighn's work (hope spelled this right, his signiture is awful!)

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This section really needs to be synched to the main article (Observable universe). --Pascal666 02:28, 21 January 2006 (UTC)

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To me, it is a logical choice that the universe is infinite.

Here's an explanation: You have space, which is nothing, but is infinite in dimensions. Then you have matter and energy. Matter likes to collect into clumps. Heres the simple question that made me understand why the universe must be infinite. If we did not have a universe with infinite matter and energy, where would it all be? Exactly, one single point.

The Big Bang: A measurable amount of matter crammed into a fine point such as what happened before the big bang needs to interact with something else to disturb its finely packed equilibrium. Think about it; Billions of galaxies packed into a small sphere. Where would the particles be distributed? Protons and neutrons would sink, and the electrons would float. Cut a ball of this tightly packed matter in half with something of comparable mass, and the packed particles are going to scatter outward real fast, and create an expanding cloud of hydrogen gas.

Forgive my rambling.

Djedi81 12:01, 2 October 2007 (UTC)

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Seeing around the universe

For the time being, I am removing the following statement from the article, because I don't see how it can be true:

"Therefore, strictly speaking, we should call the stars and galaxies "images" of stars and galaxies, since it is possible that the Universe is finite and so small that we can see once or several times around it, and the real number of physically distinct stars and galaxies could be a little smaller. There are observations underway to determine whether this is true."

If the universe were so small that one could see even once around it, wouldn't the night (and day) sky be completely bright? If the universe were unbounded yet sufficiently finite, wouldn't the "image" of the sun exist in every direction that one looked?Johnstone 13:31, 8 May 2004 (UTC)

I'd put it back in. You bring up Olbers'_paradox. See that article for reasons why the sky isn't all bright. But that doesn't depend on whether the universe is bent or flat. It's more about whether you can see an infinite distance. NealMcB 16:16, 2004 May 8 (UTC)

I was aware of that paradox, though I didn't know it had a name. It was in the back of my mind when I decided to question the material I removed. As you say, that paradox is not about the idea of seeing "around" the universe, so it does not necessarily relate to my question. However, I was thinking of the universe as a "spherical space"; I have re-read the sentences in question, and now I realize that my objections do not apply for most non-spherical geometries. I've tweaked a few words to (hopefully) clarify their meaning. Johnstone 22:51, 10 May 2004 (UTC)

What I recall reading is that it would take all time (from Big Bang to Big Crunch) for a photon to traverse a whole universe and return to its original position. Jimp 09:24, 28 February 2006 (UTC)

universe (fiction)

It might be nice to have an article on "Universe (fiction)" or something -- the sense of the word where somebody says "Many of the Marvel Comics series take place in the same universe" or "The SERRAted Edge novels are set in the same universe as the Bedlam Bards novels". Cwitty

http://www.cs.appstate.edu/~sjg/class/1010/wc/geom/finitespace.html "Is Space Finite?" by Jean-Pierre Luminet, Glenn D. Starkman and Jeffrey R. Weeks

Shape of the Universe

Hi, I'd like to question the analogue of the shape of the Universe and the shape of the Earth. There are no current experimental hints, that the Universe is not flat. This is stark contrast to our experience on Earth, where it is rather easy to find that it is not flat (ships under horizon etc.) We should change/improve that sentence. Awolf002 23:17, 10 May 2004 (UTC)

Uh, what exactly do you mean? How could the universe be flat? Assuming you're sitting in a three-dimensional chair typing on a three-dimensional computer with three-dimensional fingers, you must not mean completely flat... do you mean very wide and not very tall? And if so, why? A spherical universe seems most logical, if based on nothing but the fact that you can stand anywhere on earth, look up and see celestial bodies in all directions. Another shape would have to be based on contradictory evidence, but that applies to anything, so why specifically flat? I don't see the basis of flatness being any kind of default assumption.

At least 156 billion light-years?

According to http://www.space.com/scienceastronomy/mystery_monday_040524.html , the universe is at least 156 billion light-years across.

I changed the article accordingly. If someone thinks it was too early and we should wait until the new estimate becomes widely accepted, change it back.Paranoid 12:50, 28 May 2004 (UTC)

while changing from 50 to 78 Bly in radius, it looks like you left unchanged the language The observable universe contains about 7 × 1022 stars, organized in about 1010 galaxies,. Anyone know where that estimate came from? Based on applying the local density to the total volume? Based on observations of deep fields? Something else? If based on density, these numbers would also need to be adjusted based on the new volume. And this all relates to my question above about the number of particles in the universe. --NealMcB 00:04, 2004 May 29 (UTC)

Age - forever uncertain

According to http://www.sciencenews.org/articles/20040522/fob1ref.asp , physicists from National Laboratories of Gran Sasso found the age to be 14.7, not 13.7.

Well, kind of... You need to understand, that the age of the Universe can (and should) be obtained by many independent methods. Each of these methods has its own assumptions and systematic errors. So it is very unlikely you get the exact same numbers from all of these measurements. If the theory about the Universe (on which these numbers are based on) is correct, then these numbers should agree within their uncertainties!

The article seems inconsistent. We have one paragraph stating the age is 13.7 (or 14.7) +-.2, and another saying it is 15.556 +- 0.024 billon years. These numbers aren't agreeing within their uncertainties. We need to square this somehow, at least we should point out the inconsistency. Zeimusu 16:17, 2004 Jun 15 (UTC)

I suspect the 15.556 one is less reliable. If we knew the age with such precision, nobody would be discussing it, doing research and publishing paper about it.Paranoid 18:00, 15 Jun 2004 (UTC)

Does anyone know who wrote that stuff about "the age is the inverse square of the temperature"? I know quite a bit about cosmology, and never heard of such a formula - and actually I think that this claim makes no sense.

In another article on the age of the universe it says that "the age is the inverse square of the temperature" when measuring the universe's age in planck(not sure of spelling) units. From the description in that article these units are based on the temperature of the universe after the big bang.

WRT the 14.7 billion years, I think that was misreported in the popular science media. What the people actually showed that the age of stars and globular clusters is 1 billion years more than previously thought - but adding that 1 billion years simply to the WMAP result makes no sense, since the WMAP result does not depend in any way on the age of the stars. There could possibly be problems now that the age of some stars seems to be older than the age of the universe, but AFAIK, this is not the case, despite this age correction for the stars.

Accordingly, I have deleted this paragraph. If anyone feels it must be reinstated, lets discuss it here first. Zeimusu 12:27, 2004 Jul 23 (UTC)

well, I can claim that the universe is 20 billion years old and you CANNOT prove me wrong...=) while we may have a vague figure of the visible universe, what is beyond what our vision could reach is anyone's guess...who's to say that the next second the Hubble telescope will not see a 'boundary' somewhere beyond the deep field... I think i'm a lil bit drunk... but this stuff is fun to think about — LegolasGreenleaf 11:34, Nov 7, 2004 (UTC)

Age of Universe - Observation and Theory

The often quoted age of 13.7+/-0.2 Gyr for the age of the universe comes from the first year WMAP results: This measurement is made by using the location of the first acoustic peak in the microwave background power spectrum to determine the size of the decoupling surface (size of universe at the time of recombination). The light travel time to this surface (depending on the geometry used) yields a pretty good age for the universe. Assuming all the various models used are valid in getting to this number, the accuracy of actual data allows a margin of error around 1%.

However, this age is only accurate if the assumptions built into the various models being used are also accurate. This is referred to as “strong priors” and essentially involves stripping the potential errors in other parts of the model to render the accuracy of actual observational data directly into the concluded result. Although this is not a totally invalid procedure in certain contexts, it should be noted that the caveat, “based on the fact we have assumed the underlying model we used is correct”, then the age given is thus accurate to the specified error (since this error represents the error in the instrument used to gather the raw data input into the model).

The age of the universe based on the “best fit” to WMAP data “only” is 13.4+/-0.3 Gyr (the slightly higher number of 13.7 includes some other data mixed in). This number represents the first accurate “direct” measurement of the age of the universe (other methods typically involve Hubble law and maximum age of stars, etc). There is a sense of triumphantism in the scientific community surrounding results like this, and therefore a more careful analysis of the methods and assumptions used, tend to be overlooked.

This, of course, is a classic example of how different methods for determining the same parameter (in this case – the age of the universe) can give different answers with no overlap in the “errors”. It is quite common to see two sets of uncertainties, one related to the measurement and other the related to the systematic errors of the model. In some cases, this can not be done (in theoretical a prediction), but it is not evident why WMAP were not able to do this?

Worth checking out is Science 299 (2003) 1532-1533, available here http://arxiv.org/abs/astro-ph/0303180

There is a purely theoretical approach to calculating the age of the universe which I can outline in more detail here. This comes from a very recent development and hasn't been published yet. Even after publication, it can take some years before a new result like this makes its way into the mainstream (so don't be surprised if you have not heard about this yet.) It is probably best to leave this development out of the main page until such time as it gains greater acceptance. For now this discussion forum should suffice for a preview however:

The redshift of an object in a dynamic universe is related to a scale factor of that universe by the relation R=Ro/(1+z). Where R represents the “scale” of the universe as seen at the redshift z, where the current scale is Ro. The “scale” is just a device to measure the size of the universe, it can be thought of as the radius, but most people use the “scale factor” a=R/Ro, which would be dimensionless regardless of how you represented R.

The temperature of the universe is inversely proportional to its scale; somewhat analogous to a gas that would cool down if expanded, or heat up if compressed, the temperature of the universe is thus related to redshift as T=To(1+z). We can do a quick test by using the current temperature of 2.7K and the redshift of CMB as 1089 to calculate the temperature of the decoupling surface T= 2.7*1090 = 2943K (this is the temperature of the universe when the CMB was emitted - around the dull red glow of a hot poker.)

One of the most important cosmological models, is based on the Friedmann equations. This allows you to describe how the universe has evolved over time using an equation like this: t=to(1+z)^-3(1+w)/2. As you can see, things are starting to get a bit more tricky, but this equation simply relates the age of the universe to the redshift. This particular example has an additional term w, which comes from something called the equation of state, relating the pressure and density of the universe (p=wdc^2, where p is pressure, d is density and c^2 is the speed of light squared).

In a universe like our own, most of the contents is in the form of stuff that does not exert much pressure on its surroundings (clouds of hydrogen gas, stars etc). In this model, w=0 and is known as a pressureless, or “dust” model. Here t=to(1+z)^-(3/2), and throwing in our redshift of 1089 and a current age of the universe to=13.7 Gyr gives us around 380,000 years for the age of the universe when the CMB was emitted. This may not seem so tricky after all, but unfortunately, it is not quite that simple.

Embedded in these models is an assumption about time and an interpretation of metric distance which is not entirely correct. That is not to say that they are entirely wrong either: The metric distance defined between two points in an expanding universe increases over time. However, the General Theory of Relativity does not explicitly state how that change in distance should be interpreted. It is entirely valid to consider this change as a fundamental change in the underlying “concept” of distance (and the same situation would also apply to the concept of time).

This type of model immediately solves an important problem relating to our CMB calculation above. If the photons in the CMB went from being hot enough to fry a burger, how come those same photons can't even defrost one today? Where did all that energy go? Of course, this comes back to our idea of the change in the distance scale: These universe expands by a change in the unit system, so the temperature likewise changes with the unit system. In this context, the temperature/scale of the universe can be thought of as being constant over the history of the universe, with no loss of energy in the CMB.

Things do start to get technical here, but there is a nice confirmation of this model which actually validates it against recent observations. Coming back to the math, the change in the distance is related to time with the redshift relation t=to(1+z)^-2. However, there is an additional change in time related to redshift as t=to(1+z)^-(1/2), which (the product of both) brings us back to the original form for our “dust” w=0 universe. The idea of time-variable time probably sounds bizarre, but this is expected since there is no “absolute” concept of time in General Relativity (even though it seems people try and introduce this idea in most models.)

So this was a very round about way of saying that we can relate the temperature of the universe to the age of the universe. Since we can measure the current temperature and have a model to extrapolate back, all we need to know now is the origin of the graph and read off the age. The earliest valid point in the evolution of the universe if the Planck time. At this time, the universe had the Planck temperature at a state of essentially zero entropy. The Planck temperate is the maximum attainable temperate in the universe and can be thought of as the Hawking temperature of black hole with a radius of the Planck length.

The Planck temperature Tp comes out to around 4.5x10^30K, and we can state Tp=To(1+zmax), where To=2.725K and zmax=1.65x10^30 is the maximum redshift at the Planck time tp. We know that tp=to(1+zmax)^-2, so putting in the Planck time gives us a n age of the universe of 11.667 Gyr. This is not the end of the story however: If time was absolute and never changed, then this would be the correct value, but we need to take into consideration of the change in time over the age of the universe. This is a fairly simple integration and results in a age one third as much at 15.556 Gyr. The CMB temperature is known to a 2mK accuracy, and with some error in things like the Planck units (mainly from G), the accuracy of this age determination is around 24 Myr.

There is a simplification where if expressed in Planck units, the temperature is equal to the inverse square. Dividing To/Tp gives the current temperature expressed in the amount of the Planck temperature 6x10^-31. Taking the inverse square gives 2.72x10^60 which is the age in Planck units. Multiplying by the Planck time gives the 11.667 Gyr again. There is mainly other simple relations like this, including the critical density as the Planck temperature raised to the forth power. In Planck units, the density is 1.3x10^-121, which multiplied by the Planck density is 3.3x10^-30 g/cm^3.

This was a very stripped down and somewhat mangled explanation, but hopefully it has shed some light on the “age of the universe” question.

I notice that you not only snipped my questions and chose to ignore them; you also left our discussion in sci.astro. I count that as a defeat. You call our discussion "fruitless" - you are right there, but you might consider *who* was the one who kept ignoring questions and arguments, and thereby made the discussion fruitless...Bjoern 14:52, 3 Dec 2004 (UTC)

Not so much a defeat, as a waste of time; your questions and arguments didn't warrant the time required to address them. However, if you are still interested, I will be presenting this work at the annual meeting[1] of the American Association for the Advancement of Science on February 20th 2005 (so I need to focus my attention on that presentation for the time being).

Wow, more discussion than I was expecting! I wonder if that can be incorporated into this page or another, it was worth reading. The universe page should have 13.7 billion years as its value for the age of the universe, but I'm going to copy some of your caveats to the main page. Zeimusu 14:41, 2004 Jul 27 (UTC)

Capitalizaton

I asked this question on Talk:Kardashev scale but I'm still not confident. this article mizes and matches the use of Universe and universe. Is there a distinction between the two forms or is this a formatting error? Many articles have the word Universe capitalized but this article starts out by uncapitalizing it and then shifts to upper case. The title: Size of Universe and observable universe seems to be using both versions in one line. If it isn't an error there should be a note about it somewhere. Comments? [[User:BrokenSegue|BrokenSegue]] 03:27, 19 Nov 2004 (UTC)

Could it be that the Big Bang is what happens on the 'otherside/inside' of a Black Hole? (Hawking temp) That would provide a starting event for the expansion of this know universe and contribute to the theory of Infinity; an 'infinity of universes'; the only constant being Change/Flux.

I don't like...

Much of this article depends on the reader subscribing to the Big Bang theory for it to be anything other than nonsensical...other equally (or more) plausible theories concerning the genesis of everything exist, so should they not also be given the spotlight by this article? Redxela Sinnak 16:45, July 10, 2005 (UTC)

Fringe views belong in their own articles. Until the article on time discusses Gene Ray's Time Cube hypothesis, or Earth discusses modern geocentrism or modern Flat Earth views, this article shouldn't discuss fringe views. --brian0918™ 16:55, 10 July 2005 (UTC)

I was in no way referring to "fringe theories". Please read comments more clearly in future. Anyone else? Redxela Sinnak 11:45, July 19, 2005 (UTC)

What are the other "equally (or more) plausible" theories? I don't think any of the other scientific theories have been tested with nearly the precision of the big bang. –Joke137 13:38, 19 July 2005 (UTC)

Redxela I agree. It seems to me that the current focus on BB and the continual reference to anything other than BB as being 'fringe' stems from the simple fact that most astrophysicists, physicists, and astronomers are simply not educated in the history and dynamics of the scientific method in general. No doubt most are unsure of what the word 'paradigm' even means, completely blind to the fact that the majority of their world-view is restricted to one. (this is now a fragment.. continue with 'BB is viewed..')

Surely, you must be joking!! Are you saying, the people who work on creating a scientific theory day by day are "not educated" to address all these issues? Do you really believe, most scientists would not follow a potentially Nobel Prize winning new explanation for the genesis of the Universe? All this makes me think, that you are talking about non-scientific theories. Please, prove me wrong and give us an example. Awolf002 17:34, 9 August 2005 (UTC)

It is a rare physicist that is educated in the history of the circumstances of his science. How often where you taught in your training to go back to the fundamentals and research the original history and cultural circumstances? Here in the US most physics curriculums simply train in the presently known science with no attempt to portray the cultural and historical background of the science. Im not sure where you got the idea that I think scientists dont follow potentially nobel prize winning theories, because it seems thats all they do, regardless of their foundations and factuality! --Ionized 20:40, August 9, 2005 (UTC)

BB is viewed as correct through biased perception that simply will not be able to see it as anything other than correct. Nearly all 'tests' which verify the BB are constructed from within the BB paradigm itself. The study of the history of the field is of utmost importance, researching original papers from the pioneers themselves such as Hubble can greatly clarify which events lead to the popular acceptance of any one theory over another. Unfortuneatly, most main-stream researchers don't even question the foundations hence would never bother to take the time to research them, and indeed simply discount anyone who has done the research and knows more about it. The history behind Hubble is one of the greatest examples, for he didn't come up with Hubbles law entirely by himself, he was lead into it by colleagues. He observed a relation between luminosity and redshift, it was only latter interpretted by others as 'velocity and distance', and indeed before his death Hubble fought hard to bring this information back into the community. He didn't believe it was recessional velocity at all, there where historical circumstances which forced that interpretation upon it. Anyhow, its a shame that BB is the current focus of the major funding in the field, if all of the funding was taken away and redirected, no doubt the popular conception would start noticing the already existing evidence against the standard paradigm. --Ionized

Good to hear an echoing of my thoughts, fellow music lover ;) Quite shamefully, I cant back up my thoughts as I lost the original source of "genesis dispute". I can assure anyone reading this that it that the points raised in that article were valid. Not to put too fine a point on it, but someone better educated than me must follow up this lead. --Redxela Sinnak 11:04, August 9, 2005 (UTC)

please make this page less technical

Can someone please make space (of the universe) seem less technical? It is very confusing for the average person to understand, and it seems like the knowledge of physics is mandatory to understand any of it. Please change this.

Retrieved from "http://en.wikipedia.org/wiki/Talk:Space"

SEASONS GREETINGS 2005/2006 <spam removed-- JeremyA 01:46, 25 December 2005 (UTC)>. Thanks.

Sum of matter and energy

This is a confusing statement that is not necessarily true (especially in regards to the disambig at top referring to the observable universe). Do not continuing inserting this statement. Thanks,--ScienceApologist 16:38, 18 December 2005 (UTC)

The universe consists of energy in various forms , one of them matter ... The sum of energy in the universe is constant. Why do you disagree with that ?

The sum of the energy in the universe need not be constant -- especially if this is about the observable universe (which is continually expanding). --ScienceApologist 03:48, 19 December 2005 (UTC)

According to science the sum of energy (including matter) in the universe is constant.Energy can not be created from nothing.Energy can not be destroyed into nothing.

I know many religious people do not like the results from science - are you making religious censorship ????

I think maybe we are having a problem with English not being your first language. In any case, the article already makes the expression needed. --ScienceApologist 19:41, 19 December 2005 (UTC)

I am taking the liberty to copy the two sentences in contention:

1 - The definition of the Universe is everything that exists. Nothing exists beyond the universe.

2 - The Universe consists of energy and matter, the sum of energy and matter is always constant.

I find it rather difficult to find consensus about them with just the above arguments. Awolf002 20:21, 19 December 2005 (UTC)

Capitalization revisited

Why is universe capitalized in much of this article? Do sources outside Wikipedia capitalize it? My dictionary doesn't. Neither do any of the external web sites the article links to, at least as far as a cursory inspection reveals. — Knowledge Seeker দ 04:39, 11 January 2006 (UTC)

Agree that universe would be better lower case for an encyclopedia type article on 'universe'. Could be UK tendency to capitalize many nouns but I think we usually try to keep the style already on existing pages. Possibly, considering the type of vandalizing the page suffers, there appear agendas involving the promotion of The Universe here and related articles. --Eddie | Talk 09:34, 11 January 2006 (UTC)

I've put it in lowercase. The use of uppercase, especially in phrases such as "known universe," is non-standard and the explanation given for the use of lowercase for "parallel universes" alone is original research, to put it charitably. (And no, this is not a UK tendency.) ProhibitOnions 14:05, 11 January 2006 (UTC)

Update Tag

I was somewhat reluctant to tag it this way at first, but I feel that as the current community of physicists and other scientific disciplines dealing with cosmological principles have well advanced the theories of Albert Einstein (no offense intended there, sorry if it comes off like that) that some more modern sources are required (maybe some more current than 1952). In fact, because this Einstein source is the sole work in the bibliograpical section, I imagine that all of the subjects within the greater subject of the concept of a universe were not in Einstein's original paper. I don't have access to it at this moment but I will dig for it and retract this tag and comment if there is any discrepancy from what I feel is true.

JuniorMuruin 01:06, 18 March 2006 (UTC)

where is our universe?

on what plane of existence does our universe live on? is there someother plane bigger than universe that hold all other universes as well? if so, they where is that plane? at what point does the universe stop expanding, and what happens when that occurs?

I think you're asking about branes and the Big Bang. --ScienceApologist

When the universe stops expanding depends on the shape of the universe. If the universe is open, it will continue to expand until the Big Rip(Actually, even after the Big Rip, it will continue to expand). This can also lead to the Heat death of the universe. If the universe is a sphere, it may retract until it beomes a singularity. There are many more factors that will affect the universe's fate. If you are interested, see the Ultimate fate of the universe. Funnybunny (^talk/_{Counter Vandalism Unit}) 02:53, 21 May 2006 (UTC)

Expanding universe...

If the Universe is expanding, then what is it expanding into? Alexrushfear 17:14, 12 May 2006 (UTC)

hehehehehe72.144.128.40 19:30, 20 July 2007 (UTC)

Incomplete beginning of the article

The article should start with a paragraph treating "Does the universe exist?". Its perceived existence should not be taken at face value. it could be a mere reflection or an insignificant detail of something bigger that actually exists. Refer to the ending scene of Man in Black for a much dramatized illustration.

Grammar errors

The sentence "There is controversy over which came first in the universe: matter or energy." Just doesn't seem to fit in. I know it's not the biggest mistake in the world but could someone fix that sentence to be correct?

Uh, could you? You did add the sentence in. Splintercellguy 20:24, 10 July 2006 (UTC)

"Universe and Mind Embodiment"?

This section was added by 24.90.214.20. I'm not sure that the Wikipedia "Universe" article is the place for touchy-feely new-age hippy speculation such as this. It throws around a lot of big words but ultimately says very little. It is not scientific or supported by any other articles. I feel that this section should be removed. Any objections? I've read that fringe theories belong in their own articles, so perhaps the person who wrote this would like to create a new article or stub in the future. Bvanderveen 22:02, 16 July 2006 (UTC)

Seconded. `'mikka (t) 23:01, 16 July 2006 (UTC)

Clarifying the universe

This should add to better understanding of many aspects of the univese.

Two wrong and harmful assumptions

There are two basic reasons for the mysteries in the standard model of the universe – and they are due to two wrong assumptions that should be corrected in order to really understand our universe.

The first wrong fundamental assumption about our universe is that Newton’s laws and gravitational constant (only derived from observations in our solar system) are also valid at galactic distances outside our solar system.

The second wrong fundamental assumption is that the observed red shifts of stars show that the stars are receding and that the universe is expanding.

It is important that the scientific community take careful consideration of these two basic assumptions in order that many capable scientists do not waste any more of their precious years of research following ideas and trails that will be discarded by future generations.

The consequences of these assumptions (for over seven decades) are that they directed many excellent physicists into beliefs about the universe that are strange, wrong, and not really productive. There now are serious errors in the commonly accepted model of the universe.

GRAVITY AND DARK MATTER

The first wrong assumption is the implicit belief that Newton’s law of gravity is also valid at cosmic distances. There are no observational proofs for this assumption. In fact when used together with early observations of the motion of groups of galaxies (reported by F. Zwicki), and the motion of stars in spiral galaxies (by V. Rubin), these observations according to Newton’s laws need massive amounts of missing matter, now called Dark Matter, to explain the many observations.

The equations describing the rotation of the stars in spiral galaxies, balancing the gravitational and centrifugal force, result in M*G = r*v*v where M is the central force and G is Newton’s gravitational constant.

In regions where the rotation velocity curves are flat (constant) this requires that either M increases linearly with distance r, or that G increases linearly with distance in the region of constant rotation velocity. The usual assumption is that a linear invisible mass is the explanation for the unusual observations thus leading to a need for massive amounts of dark matter.

Actually my simple extension of the gravitational constant G consisting of an additional term linear in distance, A*r, can explain the observations without needing to search for dark matter. (This is different from the interesting MOND theory of M. Milgrom that involves acceleration.) Note that with this extension of the gravitational constant with large distances, Newton’s laws and Einstein’s General Relativity are still valid in our solar system at the smaller distances. The observed gravitational lenses are also explained without needing dark matter.

MEANING OF THE RED SHIFT

The second, and more critical, wrong assumption is that the observed red shifts are only due to the Doppler effect and presumably show that the stars with red shifts are receding.

This wrong assumption concerning the causes and meaning of the red shift has resulted in a number of even more serious errors, including the apparent expansion of the universe, the supposed initial inflation, the apparent acceleration of the expansion, and the need for Dark Energy, the wrong age of the universe based upon the Hubble constant, the big bang, Inflation, and the explanation for the Cosmic Microwave Background and its low temperature. A number of Nobel prizes were awarded based upon excellent works that unfortunately were based upon these wrong assumptions.

The red shift initially termed by Hubble as an “… apparent Doppler effect …” is supposed to measure the apparent receding velocity of remote stars, leading to the conclusion that the universe is expanding. This apparent expansion encouraged Einstein to remove his cosmological constant, which he previously had inserted into his equations to support his belief (wish) for a static universe.

Actually, there are three additional contributions to the red shift and they are only due to gravity. The first is for photons leaving large masses. The results are that massive quasars can appear to have large energy output, and transverse (angular, “proper”) velocities greater than the velocity of light. This is because the apparently large distances determined from the red shift make the quasars appear to be further away. This also explains why galaxies that appear to be connected by streams of stars (H. Arp) also show different red shifts indicating large differences in distance (a massive black hole in the further galaxy adding to the red shift).

The second contribution to the red shift is for photons traveling large interstellar distances and is due to gravitational drag by interstellar dust and gas (without collisions or absorption and reemission that would blur images). This is similar to the gravitational drag by our moon on Earth tides causing the moon to lose energy, without needing blurring effects on the photons.

The third contribution is due to the long-range drag by the extended gravitational constant (related to the apparent dark matter), and adds a new logarithmic term, ln(r) as a contribution to the red shift. The logarithmic term arises from the integration of the force with the inverse r term in the extended gravitational constant with respect to distance to determine the loss of photon energy.

The apparent accelerating expansion of the universe is due to the observations that very remote stars are dimmer (and further away) than predicted from their observed red shifts based upon the Hubble linear relation ship between red shift and distance (S. Perlmutter). The result is the apparent need for Dark Energy to power the acceleration.

For very remote stars, determination of distance from red shift and the Hubble constant is no longer linear and should be corrected by the ln(r) contribution for the extreme distances. This error makes the distance for very remote stars based upon intensity much larger than expected from the assumed linear red shift. The wrong interpretation of distance based upon observed red shifts and distances of very remote stars resulted in the wrong concepts of accelerating expansion, and dark energy to provide the reason for the differences between red shift distance and the light intensity determination.

The cosmic microwave background is caused by the effect of gravity on photons traveling long distances to reduce the photon energy to the microwave range. Gravitational interactions will equilibrate the microwave photon energy to thermal equilibrium with the very low (2.7 K) temperature of interstellar gas and dust.

The loss of photon energy traveling from very remote stars will shift the wavelength out of the visible range – and this explains Olbers paradox (why the sky is black in spite of the vast number of stars).

SUMMARY

A careful, open minded review of the points raised here could be beneficial to the future progress of the scientific community although the results could be upsetting to many intelligent and productive experts working in this field.

If you feel that these explanations have merit, please feel free to send a copy of this document (unchanged) to your friends and colleagues.

Sol Aisenberg, Ph.D. 36 Bradford Road Natick, MA 01760 U.S.A.

508/651-0140 itgplus@earthlink.net To be updated: http://inventing-solutions.com/simplified-universe.htm

That's interesting stuff and I would be happy to see it on the main page... once it's published in a peer-reviewed scientific journal. SheffieldSteel 19:14, 1 March 2007 (UTC)

Link leads to disambiguity

Where is Null under See Also fit in? I'd fix it but i can't figure it out.

When was the density equal to water?

How long after the big-bang did it take for matter in the universe to reach a density equal to that of water? Also, how long until a density equal to that of air at sea-level was achieved? Thanks

Problem in para - anyone know what this is supposed to mean??

I edited out this rather confused segment, be grateful if someone can (a) explain what it's all about and (b) make some sense of it in the right page context:

"== Hisgalaxy formation theory predict more nearby small galaxies than observed.

passes through the intervening gas clouds. The ionization of these gas clouds is determined by the number of nearby bright galaxies, and if such galaxies are spread around, the ionization level should be constant. It turns out that in galaxies from the period after cosmic reionization there are large fluctuations in this ionization level. The evidence seems to confirm the pre-ionization galaxies were less common and that the post-ionization galaxies have 100 times the mass of the dwarf galaxies. tory of the universe ==" MarkThomas 19:54, 26 August 2006 (UTC)

This whole theory is illogical

Question #1: If there is a Big Bang, where did everything come from before that? And the answer that it all shrunk down to some superball only leads to "where did that come from?"

In fact, the entire theory makes absolutely no sense, except to say that we do not understand the core nature of both mathematics and of physics.

Far too much money is wasted on this meaningless research, really, while the pseudo-intellectuals debate the trivialities of Big Bang and other theories, what's really needed on this planet are solutions on this planet, and not idylls of the rich wasted money on what is nothing more than a trick to avoid the needed responsibilities. Not unlike kings and emperors playing darts while large portions of their populations go starving, or worse, are used for another game, genocidal chess.

AHEM. The self irony of just what you've written. above! Followed by even funnier stuff in which you expect us to waste our time paying attention to what YOU think about such matters, which you've just said aren't themselves really important enough to warrant attention. Hmmm.

Listen, Bub, FYI this TALK section is for the "special interest group" of people who are interested in the Wiki article on the Universe. If you're interested in other stuff, go attend to them. Don't come and bother us, HERE. Next, there's actually no place on WIkipedia for your pet unified physics theories. Put them on your web page. I'm SURE that HERE is not the place for them. So I'll be deleting them. Anybody interested in them can recover them from this page's history. SBHarris 20:09, 10 February 2007 (UTC)

sbharris... What's "pet unified physics theories" supposed to mean? do you get a kick out of belittling people like that? Let me inform you sir, that the Big Bang Theory is just a Theory and so long as its a theory it's nothing but an opinion emphasized and agreed upon a wide amount of pompous scientists. Why don't you draw your own conclusions instead of being so EASILY influenced by a piece of paper claiming the existence of the Big Bang Theory. Maybe i shouldn't make such a big deal out of this but i tend to find your kind quite rude and arrogant.

A Map of the Universe

A recent publication :: http://arxiv.org/PS_cache/astro-ph/pdf/0310/0310571.pdf :: includes a link (on page 50, http://www.astro.princeton.edu/~mjuric/universe ) to the various maps produced by the analysis. The linked-to page includes statements to the effect that the maps may be reproduced for 'classroom wall' display. Could/should they be incorporated into the wiki Universe article, i wonder? ed. (newolder)

Origin of name, "Universe"?

Kent Hovind said the name, Universe literally means a single spoken sentince. Uni meaning one, and verse meaning a single spoken sentence. As such he insinuates that the word, "universe" comes from the idea of god creating the universe by speaking it in one sentence. Is there any truth to this? Inforazer 14:00, 20 September 2006 (UTC)

I have found two etymologies, but not that one (yet). Most commonly, dictionaries state something like "From Latin universa, unus or uni one + versus from vertere turn Via Old French univers. Originally literally all turned into one." ^rossnixon 09:36, 13 October 2006 (UTC)

uni verse = one word or all things accomplished in one word

Also, see this: Special Dispensation for the Big Bang theopsis

--CyberSongs 20:02, 16 October 2006 (UTC)

"Seems nonsensical"

My edits to the section "Size of the universe and observable universe" were just reverted with the comment "seems nonsensical". I'm concerned about this, because an encyclopedia article isn't very useful if it reads like nonsense. The fact is, though, that a lot of the old information in this section was just wrong, and it desperately needed rewriting.

The old content of the section was longer and had two references, both of them to poorly researched, inaccurate web articles distributed by general news sources. My revised version is much shorter and has only one reference (to an actual research paper). I deliberately reduced the size to avoid duplicating information that's already on the Observable universe page. I also updated Observable universe to explain why the numbers previously quoted in this section are wrong.

There's an unusually large amount of misinformation about big bang cosmology in the popular press, and I want to impress on people that just because you read in BBC News or Discover magazine that the universe is 156 billion light years wide doesn't mean that it actually is, or even that any cosmologist has claimed that it is. -- BenRG 15:15, 18 November 2006 (UTC)

Failed GA on 12/3/06

I'm sorry, but this article has a few issues (and one glaring problem) that need to be corrected before it can become a Good Article. As per WP:WIAGA:

• 1(a)- well-written/prose: A lot of individual phrases needed to be changed. To wit:
  • From "Expansion": "...the farther away from us galaxies are, the faster they move away from us." Writing should never be done in the first person; in this case, "us" should be "Earth."
  • From "Expansion": "As with most things in physics, that certainly wasn't the end of the story, as attested by the update and reissue of The First Three Minutes in 1993." This is an incredibly unencyclopedic sentence. I certainly do not want to sound condescending, as a lot of hard work has obviously been put into this article, but "that certainly wasn't the end of the story" is simply unacceptable.
  • From "Pre-matter soup": "..the first hundredth of a second was a bit of a mystery." Again, "a bit" should be changed. Ditto to "Fast forwarding to after the existence of matter..." from "First galaxies," "...there is no reason to believe that this bound is anywhere near right" from "Size," and a handful of other phrases that need to be improved in tone.
• 1(c)- WP:MOS adherence: There are no real style problems, except for there being far too many external links. Please see WP:EL; external links should be kept to a minimum and only added when necessary, which many of these are not. In addition, it would be a good idea to list what source each link comes from, as opposed to simply including the article's title. This is not a big deal (one could simply scroll over the link to see the address), but it's a little touch that can go a long way.
• 2- factually accurate and verifiable: The big one. The article currently has two {{citation needed}} tags, but there could be many more. For a topic this expansive, having only four references equals not having nearly enough references. I doubt there are any Good Articles within all of Wikipedia that contain so few references.

I know that this article could easily be a GA if a little more work is put into it. There are a lot of things to like about this article- it's very comprehensive, it's got an excellent image, and it's NPOV, touching on many different theories. Best of luck, and feel free to resubmit to WP:GAC when the above issues are addressed. -- Kicking222 16:25, 3 December 2006 (UTC)

How many stars in the universe?

I didn't see an mention of how many estimated stars in the universe (i.e. how many total stars in all galaxies). Any idea? --Calan 19:57, 23 December 2006 (UTC)

From star, "A typical galaxy contains hundreds of billions of stars, and there are more than 100 billion galaxies in the observable universe." So it's about 10^22, and should probably be in the article. Xiner (talk, email) 22:35, 3 January 2007 (UTC)

Etymology

I just added the etymology info from Wiktionary, which I assume is kosher. I don't know if it's necessary (or even welcome) to cite taking info from a sister project. Drooling Sheep 09:46, 4 January 2007 (UTC)

footnote one

"It is not known whether the whole Universe is observable . . ." To me this seems like an unnecessary sentence. In any case, footnote one, which is the reference citation for it, does not make a statement about this that I can see. Sincerely, Mattisse 19:10, 4 January 2007 (UTC)

Whether or not the whole Universe is observable makes a huge difference. Please read the reference again, and read the review papers listed in that reference. Thanks. Boud 14:52, 5 January 2007 (UTC)

introduction reworked

i've done a major reworking of the introduction, trying to retain the various contributions of different editors while also trying to make it short, correct and complete. This is not easy, because practising cosmologists are not always careful about their use of terms - partly because people doing research know the concrete meanings of the terms, while researchers talking to or writing for the general public have to simplify things, which is difficult to do without saying things that are incorrect, confusing or misleading. But hopefully this wikipedia entry will soon be correct, clear and reasonably complete. :)

TODO:

• Some of the bits of the introduction should probably be expanded in the main part of the article.
• We should check usage to see if "observable Universe" or "observable universe" is more frequently used in scientific articles. http://arxiv.org/find/astro-ph
• The present version is a bit English (language)-centric. Many languages do not have articles, so the distinction between "the" and "a" universe does not exist in those... universes ;). Many scripts do not have upper/lower case, in which case there's no way to distinguish "Universe" from "universe". On the other hand, most modern cosmologists publish nearly all of their articles in English. This is too much detail for the introduction - but can we omit it totally?
• Cosmologists frequently switch between space-time thinking and comoving space thinking. Is this done correctly and clearly (for those who wish to know the difference) in the present version?
• i'm not quite sure where to put: Philosophy deals with the related philosophical notion of the world.
• i've removed this bit since i think it's redundant and the intro is long, though i understand the motivation (to make it clear that this is a physics model not a postmodernist or religious intuition or poetry). Both theorists and observers base their models by assuming fundamental theoretical principles and laws that govern matter, energy, space, and time (all of which are tightly interrelated to one another). These principles and laws are constantly tested empirically.

Boud 15:19, 9 January 2007 (UTC)

The opening sentence shouldn't be the origins of the word. Ideally it should be of the form 'The Universe is...'. I don't think it's necessary to bog the intro down with excessive collaries, such as 'Physicists' concept', given that there is a disclaimer at the top.--Nydas^(Talk) 17:03, 9 January 2007 (UTC)

A couple of comments per the WP:MoS:

• Wikipedia:Lead section—The lead should be capable of standing alone as a concise overview of the article.
• Wikipedia:Manual of Style (headings)—Avoid restating the subject of the article or of an enclosing section in heading titles.

Thanks. — RJH (talk) 18:43, 9 February 2007 (UTC)

Failed "good article" nomination

This article failed good article nomination. This is how the article, as of February 10, 2007, compares against the six good article criteria:

1. Well written?:-The lead section needs a lot of work (the universe in philosophy is not mentioned in the body). There is also a tag complaining about the informal tone in the article.

2. Factually accurate?:-There are citation tags all over the article. The lack of citations make some elements at least seem like original research such as the place underneath the formal tone tag. I would ask that you refrain from putting an article for a GA nomination with tags on the article, even if it is after an AID.

3. Broad in coverage?:-This article fails to consider philosophical and religous views on the origin of the universe.

4. Neutral point of view?:-Lack of citations and selective information would give the indication of POV, but I believe this is more a verifiability and broad in coverage problem.

5. Article stability?-No edit war that I can see

6. Images?:-Good amount of images

When these issues are addressed, the article can be resubmitted for consideration. Thanks for your work so far.

GA review (see here for criteria)

1. It is reasonably well written.

   a (prose): b (MoS):

2. It is factually accurate and verifiable.

   a (references): b (citations to reliable sources): c (OR):

3. It is broad in its coverage.

   a (major aspects): b (focused):

4. It follows the neutral point of view policy.

   a (fair representation): b (all significant views):

5. It is stable.

   

6. It contains images, where possible, to illustrate the topic.

   a (tagged and captioned): b lack of images (does not in itself exclude GA): c (non-free images have fair use rationales):

7. Overall:

   a Pass/Fail:

--JEF 17:17, 10 February 2007 (UTC)

confused :/

tried to rewrite no avail plz tell me what matter-soup is ? Pipsqueak007 00:37, 16 March 2007 (UTC)pipsqueak007Pipsqueak007

Beginning and End

Hello, I am into black holes, universe, astronomy;; to answer your question;; where did Big Bang come from, first of all, that waas never proven, it's still and will remain theory and even hypothesis, ok. Its possible there were many big bangs. And there may be more. The visible Universe we see goes back no more than 20 000 000 000 years. It's possible there are other universes, within multiple universes, multiverse. Same question remains if God has no beginning and no end, who created him, too much to know... But is there better theory than Big Bang? How many r there? User_talk:Researchlady

Be careful, very careful, if you are "into black holes". They are hard to escape from. ^rossnixon 02:31, 5 April 2007 (UTC)

Very likely simply we're living inside an immense computer whose sole purpose is to determine the meaning of life and existence. We don't ever want to find the answer though as that will bring the program to an end. Sleep well... ;-) — RJH (talk) 22:42, 27 April 2007 (UTC)

Universe and Dimension

Is there any difference between a universe and a dimension? I do think so, but since when you go to the disambiguation page for dimension, it says, at the bottom, that it might refer to simply an alternate universe. ♠Tom@sBat 01:49, 9 May 2007 (UTC)

No cite of evidence for this

"During the early phases of the big bang, equal amounts of matter and antimatter were formed."

I believe this to be an assumption until shown otherwise. Brian Pearson 20:56, 30 May 2007 (UTC)

Well, isn´t there always an equivalent amount of matter and anti-matter? ♠Tom@sBat 21:32, 7 June 2007 (UTC)

I don't know. I've often heard it said that there's always been the same amount of each, but since then I've questioned it as possibly an assumption which somehow transmuted to "common knowledge". I'd like to see evidence showing this equivalence. Brian Pearson 04:21, 19 June 2007 (UTC)

The number of CMB photons compared to the number of baryons is all the evidence required to show this. See baryogenesis for more. --ScienceApologist 13:22, 19 June 2007 (UTC)

As a layman, I'll need a bit more convincing. BTW, I was reading about how they were estimating the size of the observable universe. They did not try to estimate the unobservable universe, which to my mind, would encompass a sphere having a diameter of 32 billion light years. It seems to me we should be able to estimate the whole, given what we can see. Brian Pearson 00:39, 24 June 2007 (UTC)

If the universe was closed and had a measurable curvature, it might have been possible to estimate a size of the unobservable universe. However the universe appears to be flat or open, so there is no evidence that it is of finite size. The equal amounts statment may have to be changed to say that there was slightly more matter than antimatter, otherwise there has to be an explanation of why is there more matter in later times as we observe now? However it says 'formed', and if the matter/antimatter was formed from photons, that would be the case. But was there always more matter than antimatter? GB 03:27, 24 June 2007 (UTC)

I was just reading some of the earlier comments. One person posted a link [2] in which there was an estimated diameter of 156 billion light years. BTW, I find it incomprehensible that we would have an infinite universe with an infinite amount of mass. I would think that a 'Bang' would produce a spherically shaped universe. Brian Pearson 16:33, 27 June 2007 (UTC)

Speculative Questions

I'm unsure if there are scientists out there who have looked into these questions, but if there are could you give possible ideas/theories about these questions: 1. What is at the edge and beyond the Universe and then whats beyond that? 2. Where did it come from and what was in the space before the Universe?

I find it all facinating, its just annoying that we probably won't have many answers in my lifetime. (Simon.uk.21 10:27, 14 July 2007 (UTC))

Yes, it is extremely annoying. But from what I've read, it seems after awhile, the path of light emitted outword, eventually curves back. Therefore spacetime, at some point, "peters out". Distance becomes meaningless. Just the same, I'd like to speculate that somewhere out there, there are other universes -- maybe an infinite number of them. But, we may as well be talking about an exchange of information from someone inside a black hole. There can be no information from other such universes to ours which would verify that. Brian Pearson 16:48, 17 July 2007 (UTC)

In some versions of FLRW cosmology, light eventually returns to its starting point (assuming it isn't absorbed or deflected en route). But that's not because space "peters out", it's because space has a spherical geometry and the light circumnavigates the sphere. The total volume of space is finite in this case. This doesn't appear to be the case in the real world. It's just possible that space might have a spherical geometry, but even so the light wouldn't return because of runaway expansion.

As for what's at the edge, (a) there might not be an edge, (b) there might be an edge with nothing beyond it (not even empty space), or (c) there might be an edge with something beyond it whose nature we don't know. In the time direction, there might not have been anything before the current expansion (not even time), or there might have been something whose nature we don't know. There's no apparent way to settle these questions, at least for now. There might be other universes, but there's no apparent empirical way to detect them, so that's also not a scientific question, at least for now. Of course, it's just as unscientific to claim that they don't exist as to claim that they do. -- BenRG 17:22, 17 July 2007 (UTC)

The curvature, or the path that light takes, would define the "edge", I suppose. Then, there would be no "spacetime" Beyond that. Brian Pearson 04:43, 23 July 2007 (UTC)

U and u

The first sections spend too much time discussing naming conventions. Can we make a Capitalization of universe (or similar) section that discusses the opposing uses, and then chooses the most neutral and readable naming convention for the rest of the article? Zojj 09:31, 15 July 2007 (UTC)

I moved all the U vs u discussion to one section. Zojj 08:22, 18 July 2007 (UTC)

I Have a Question, Universe Age/Size

I must admit that I am a computer scientist (with a hobby slant towards comparative religion), not a physicist, So I must begin with the disclaimer that I have no idea what I am talking about. However, as I read this article I had a few glaring unanswered questions. First, if the universe is approximately 13 Billion years old, then at first glance it seems that its radius could not be more than 13 Billion light-years, with a diameter of twice that, 26 Billion light years across. However, the minimum bound for the universe's size is stated as 78 billion light years for the diameter. Now, I know that weird physics abounds, and that there is likely a good explanation for this discrepancy. I am sure that there is an answer, but I can't be the only one who looked at this and thought, "what in the world?" An explanation about how this is possible would be a great addition to the article. Thanks --Jlc46 23:12, 9 August 2007 (UTC)

Expansion[3] of the universe is not just the galaxies physically moving apart. Spacetime, itself, is expanding, but I believe most of this expansion was nearer the beginning of the universe. Brian Pearson 02:20, 11 August 2007 (UTC)

I was hoping that a good explanation could be added to the page itself, since I believe that this would be a common question. I am not sure that I understand your answer, all objects in the universe were in one location at the time of the Big Bang, and now they are further apart than should be possible without traveling faster than light. I was expecting some relativistic answer, (like it has been longer from the perspective of the items furthest apart, or the like) but you seem to be implying that items can get further apart in less time than the speed limit of light allows IF space itself expands under them. Since space is defined by distances, force, and time, (and the force required to cause acceleration to get one item to another in a certain amount of time) I guess that I can't quite wrap my brain around how space can expand without simply meaning that the only items IN space spread out, thus expanding space/time. If it is the expansion of the items that caused the expansion, then how can we use that expansion to explain their super light speed movement? If the expansion of space/time means something other than this, then what does it mean? --Jlc46 00:47, 13 August 2007 (UTC)

I agree it should be written so people who are less familiar with the topic can better understand it. Brian Pearson 04:03, 13 August 2007 (UTC)

Basically this is a magic/pseudoscientific "fudge factor". These are often required in science to fill in gaps that otherwise would require the existence of God to explain. ^rossnixon 02:41, 13 August 2007 (UTC)

You might be interested in reading the big bang article. The 'Bang' was not an explosion like dynamite, but an explosion of spacetime, probably with emphasis on the fourth dimension, space. Brian Pearson 13:31, 13 August 2007 (UTC)

Have you seen this "New Scientist" article [4] from 2004? ^rossnixon 02:30, 14 August 2007 (UTC)

Yes I have. It is not factual. Example: A star that is 13 billion years old [5] No 'fudge factor' needed. Brian Pearson 03:49, 14 August 2007 (UTC)

Full size galaxies 12 billion light-years distant discovered last week? [6] - this was supposed to take billions of years - maybe we need to "think outside the bang". ^rossnixon 11:09, 15 August 2007 (UTC)

Did you even read the article? It's about how there's still more to know about galaxy formation. There's nothing about disproving the big bang. You read into that yourself. GSlicer (t • c) 02:52, 16 August 2007 (UTC)

It's difficult to know how to explain this without getting into the details of the FLRW model, but maybe the following two points will help:

• Special relativity is a good approximation in many situations, but it's totally wrong at cosmological scales; you really need to use general relativity. Many concepts from special relativity don't carry over. For example, it's simply not true, in any meaningful sense, that light that has been traveling for a time t has traveled a distance ct.
• The distances like 78 billion and 46.5 billion light years are "comoving distances", which means they're measured in terms of the size of the universe in the present era. For very distant objects, the light we see was emitted when the universe was much smaller, and so its travel early on "counted for much more" than it would now. Instead of thinking of the universe as being smaller in the past, you can think of the speed of light as being larger; it amounts to the same thing.

Is this helpful? Should it be added to the article? -- BenRG 23:30, 18 August 2007 (UTC)

I recently read that the bang took place in the first few seconds (how 'long' those seconds were, relative to seconds today, are another question), but I've also read that there is still a certain amount of expansion above and beyond that as explained by inertia or dark matter, and blue shifts or red shifts. I think some clarification would be helpful to the reader, but I recognize that there may still be some questions about what we know. It's possible those 'in the know' find it hard to see a perfectly good piece of writing from a novice's point of view. On the other hand, I can see how the size of an article can be too large, just trying to explain every detail. The interested reader should be expected to explore links and sources up to a point. I guess the whole thing comes down to a kind of balance. Since I'm not an experienced editor, I wouldn't be able to make that call. I do wonder how many people look at a given article and scratch their heads. Brian Pearson 01:37, 19 August 2007 (UTC)

It's been a long time since I was in school. But it seems to me light emitted from comoving sources would fit the Special Theory, while at the same time, the General Theory wouldn't rule out what you are saying. I'm a little vague on that. It seems the GT mostly deals with gravity. Brian Pearson 01:20, 21 August 2007 (UTC)

How to say Universe in German

The German language has a beautiful, poetic word for Universe: das All. Normally I'd think "universe" is an advanced concept and so would be polysyllabic in every language (monosyllables being reserved for basic concepts like: man, child, eat, run). Not in German: Das All. I would mention this in the Universe#Other terms section but I can't think of an economical way to work it in. I'll leave it for someone who has time. -- JEBrown87544 15:10, 6 September 2007 (UTC)

Definition Problems

Wikipedia’s present definition of the universe is “The universe is the summation of all particles and energy that exist and the space-time in which all events occur.” I’m OK with the words in that definition until it reaches the word summation. If the people who think the universe is infinite are right, summation is out the window.

The next troublesome word is particles. Basically there are two kinds of particles: elementary particles that contain no component particles and composite particles that do contain them. Didn’t the definers realize that the present day elementary particles are those of the standard model of particle physics, a model that does not account for gravitational force? Without gravity there would be no sun, moon, or stars, not even air to breathe. Until somebody comes up with elementary particles that account for gravity, we can forget about elementary particles.

As for composite particles, if you add a composite particle to the sum, the definition‘s "all particles" requires you to also add its component particles to the sum. That’s like being charged twice for the same automobile (once for the auto and then for each of its components). You shouldn’t let a car dealer or a cosmologist get away with it. Whether elementary or composite, scratch particles from the definition.

If particles can’t be summed, how in the world can their gravitational and kinetic energies be summed? Goodbye energy.

We are left with space-time, which is a construct of an abstract mathematical model. Constructs and models exist only in the mind; they don’t belong in a definition of the world outside the mind. Space-time vanishes, leaving the following definition: the universe is the ______ of all ______ and ______ that exist and the ______.

Definers, back to the drawing board!

Nafyladok 15:13, 18 September 2007 (UTC)

Defining terms like "life" and "the universe" is effectively impossible. I don't much like the current definition, but it's probably unreasonable to expect anything better.

"Summation" is being used in its ordinary English sense, which is closer to mathematical set union than to mathematical summation. It could be replaced with "sum total" or "collection" or "aggregate" or just deleted (along with the two bracketing words).

The distinction between elementary particles and composite particles isn't important here, provided you interpret summation in its colloquial sense. The universe contains both valence electrons and atoms. I imagine gravity was supposed to be included in "the space-time in which all events occur." "Particles and energy" is arguably redundant.

Spacetime is as real as elementary particles are. -- BenRG 16:07, 18 September 2007 (UTC)

Per your suggestion let’s delete summation and its two bracketing words, redefining the universe as all particles and energy that exist and the space-time in which all events occur. Shall we use the word all in its collective or distributive sense? Here’s an example of the collective sense: “The weight of all the rice grains in that bag is one kilogram.” The collective sense of all implies mathematical summation, which, as I have shown, leads to universe definition problems.

In the sentence “All cats are gray in the dark.” the word cats refers to the abstract class of which each member is a cat. Here the word All is used in its distributive sense meaning any or each and no summation is implied. If all is taken in its distributive sense for the universe definition, the universe would be an abstract class (the universe class) whose membership consists of all particles and energy that exist and the space-time in which all events occur. While we’re at it, if we’re making the universe merely an abstract class, let’s just say the universe is the class of all things that exist. That way the universe could include the sun, moon, stars, galaxies, clusters, atomic nuclei, orbital electrons, particles, energy, and even you and me. If space-time exists we can throw that in as well.

But, defining the universe as a class is not without problems. Once the rules for membership in a class are specified, that class can never change. To change the membership rules is to define a different class. The universe class, being an abstract notion, cannot have physical properties such as density or age, let alone temporal variation of properties. Defining the universe as an abstract class is obviously not satisfactory for cosmologists. They need a definition of the universe as a thing that is as real as a star, galaxy or cluster, so it can also have real properties.

Definers, back to the drawing board? -- Nafyladok 14:18, 27 September 2007 (UTC)

Neutrality

I don't see any mention of Creationism here. This article doesn't meet the neutrality policy, IMO. --Agüeybaná 23:27, 26 October 2007 (UTC)

What sort of mention did you want to see? It's hard to know what to say about it except "some people believe that the universe was created by some form of deity; see creationism." It might be reasonable to link to creationism in the "See also" section. -- BenRG 14:53, 27 October 2007 (UTC)

There's already a link to religious cosmology - I don't see a reason to give undue weight to creationism by specifically including it and not other alternative viewpoints as well. Ciotog 16:28, 27 October 2007 (UTC)

I don't see a link to Flying Spaghetti Monsterism either. If Creationism has to be mentioned, I demand my religion gets equal time as well.Rglong 03:50, 29 October 2007 (UTC)