Talk:Cosmic Background Explorer/Archive 1

Archive 1

Our galaxy in the center

Is it true that our galaxy is in the center of this map? If that is the case, I would bet anything that as a model it is nearly worthless. If we have learned anything in the past about cosmological maps, earth centric models are wrong, wrong, wrong. To me this shouts out more about our limitations in measurement, i.e., how far we can "see," than anything else. —Preceding unsigned comment added by 66.94.176.22 (talk) 01:10, 16 September 2008 (UTC)

The map has been oriented so that the galaxy lies along the centre, for display purposes. During the analysis of the map, the galaxy emission is subtracted out, and the CMB is analysed in such a way that it doesn't depend on the angle that the map is at. It is the least earth- and galaxy-central that we can get it without actually leaving the galaxy. Mike Peel (talk) 11:38, 16 September 2008 (UTC)

Why is the rest of the universe symmetrical about the center? If this map shows all there is and we are in the center, how could it be represented otherwise? —Preceding unsigned comment added by 66.94.176.22 (talk) 05:10, 18 September 2008 (UTC)

The map shows the cosmic microwave background anisotropies as it appears to us now, hence it is centered on us. If we were able to put COBE (or WMAP or Planck ...) in the Andromeda galaxy, we would see slightly different cosmic microwave background anisotropies. If we were able to put it very far away (say, 10 billion light years away) we would see very different anisotropies. If we went back in time a few billion years, then again it would be different (and the average temperature of the CMB would have been higher). Unfortunately, we are stuck in a very small area surrounding Earth, so we only get to see one.

Note that we tend to distinguish between the whole universe - i.e. everything - and the observable universe - which is everything that light has reached us from. As light travels at a fixed speed, the observable universe is naturally a sphere centred on us. That puts no constraints on the actual universe, as that is bigger than the observable universe (or if it isn't, then we haven't spotted any signs of that yet).

Hope that all makes sense. Mike Peel (talk) 08:41, 20 September 2008 (UTC)

Thank you for your reply. I'm not sure what you mean by the observable universe. Does that simply mean everything we can see - and is therefore not necessarily the universe at all - or does it imply that we see all the light that can possibly be seen in the universe? The term seems unnecessarily vague. If it is the former, then why use the term universe at all. Full sky seems much more to the point. —Preceding unsigned comment added by 66.94.176.22 (talk) 09:40, 20 September 2008 (UTC)

See Observable universe. It is everything we can see at the present time. In the past, it was smaller. In the future, it will be larger. There is no evidence that the universe is the same size or smaller than the observable universe (e.g. people have looked for repeating structures, which you might expect if the universe loops round on itself), and it's widely expected to be much larger than the observable universe - but we'll probably never know for definite how big it is. Mike Peel (talk) 10:54, 20 September 2008 (UTC)

Thank you again for responding, I can make an argument for using the phrase "observable universe." That is, one is using the term universe to mean everything in a given domain. In this case everything that can be detected. It seems to me that the phrase is unnecessarily confusing, however. Why use the term universe at all in a cosmological discussion unless it is to represent the Universe with a capital U. That is, the Universe that is everything - not just what is detectable. I really think this is a big deal if you want cosmology to be comprehended by laymen. If on the other hand, you are writing for professional cosmologists, they will most likely know what you mean. —Preceding unsigned comment added by 66.94.176.22 (talk) 03:10, 21 September 2008 (UTC)

BTW, the klein bottle or mobius strip idea of space folding on itself would probably not be proved by finding repetitions. If space turns out to be infinite, one would expect repetitions. It just seems to me outrageous boasting to suggest that we can know how something began when we can't even know how big it is. I watched the show, The Atom last night. It is hosted be a Mr. Jim Al-Kalili. In it, he states that the big bang theory has been proven and that we know the number of atoms in the universe. Later he back-peddles and talks about the known universe, but most people will probably not hear the back-peddling. The "popularization" of physics seems to have led to gross misleading hyperbole. Basically, from what I can sift out of the rhetoric, We can see what might be a very small part of space, we know that there is microwave radiation all around us, and that radiation has variations like ripples in a pond.

Why not state the case plainly then. If there is something wrong with what I'm saying here, then it's wrong; otherwise, please, let's state the facts without hyperbolic terminology and grand theories. —Preceding unsigned comment added by 66.94.176.22 (talk) 18:47, 21 September 2008 (UTC)

This work helped cement the big-bang theory of the universe.

What is meant by the following:

"This work helped cement the big-bang theory of the universe."

What is meant by the term "cement?" Does it mean that the theory has been written into stone? Is it still a theory? Should it say something like: This work has supported and not detracted from the Big Bang theory. Has it supported or detracted from any other theory? What has it done to the steady-state theory?

I've rewritten this. Basically, it provided supporting evidence for the big bang theory, and solid state theory etc. was not able to explain what COBE saw. Mike Peel (talk) 08:48, 20 September 2008 (UTC)

I'm sure this is just a slip, but you mean "steady state theory" not "solid state" which generally refers to the study of rigid materials. 124.149.183.81 (talk) 07:04, 11 July 2010 (UTC)

full maps of the CMB

What is meant by the following:

"This operation was able to create full maps of the CMB by subtracting out galactic emissions and dipole at various frequencies."

Does full mean full universe, full spectrum, or something else? This is not at all clear. —Preceding unsigned comment added by 66.94.176.22 (talk) 23:00, 19 September 2008 (UTC)

That should have read "full sky maps", i.e. the scientists involved subtracted out a model of our galaxy to look "behind" it. Mike Peel (talk) 08:49, 20 September 2008 (UTC)

graphical error

there is an error with the line under history going thru the box of information on the right. I don't know enough about editing Wikipedia entries to fix it.

Peer review

I think this article is a great example of a spacecraft article and I'd like to get it upto standards of a FA. It is also become mor relevant with the award of the nobel prize in physics to 2 of its principle investigators. - Ryjaz 15:14, 3 October 2006 (UTC)

I have left extensive comment on the peer review page. My one biggest comment is that this article fails to say anything about the telescope's instrumentation in any detail. In my opinion, this is crucial to understanding COBE. (This is one of the first things I look up when I read about professional telescopes.) The article also needs more science information, and some science sections need signficant revision. GeorgeJBendo 22:09, 11 October 2006 (UTC)

nobel

uhhh.. shouldn't this mention the nobel prize somewhere?

- it does in the history section "The Nobel Prize in Physics for 2006 was jointly awarded to John C. Mather NASA Goddard Space Flight Center, Greenbelt, MD, USA, and George F. Smoot University of California, Berkeley, CA, USA "for their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation"" Ryjaz 15:28, 4 October 2006 (UTC)

References

STRUCTURE IN THE COBE DIFFERENTIAL MICROWAVE RADIOMETER 1ST-YEAR MAPS in Astrophysical journal 1992 should be mentioned somewhere!--Stone 17:08, 4 October 2006 (UTC)

Launch information

It would be nice if the article mentioned that COBE was launched from Vandenberg Air Force Base, not from Kennedy as I'm guessing most people would conclude. I don't think that most people are familiar with sun-synchronous orbits, and that they require a polar orbit, which means launching to the south from Vandenberg vs. launching to the east from Kennedy. I was at Vandenberg at the time of the launch preparations, and I know all the folks that put in many hours of work on COBE would appreciate being mentioned. spn155.100.163.152 18:57, 9 October 2006 (UTC)

Clarification

Though I don't necessarily agree with it, I think it should be mentioned how commonly this is referred to as the the "Chew Or Be Eaten" mission. Barring any objection, I will probably make the change in about two days. 68.77.59.32 17:45, 24 July 2007 (UTC)

I couldn't find any hits googling for "chew or be eaten" COBE, or "chew or be eaten" --64.173.240.130 (talk) 21:33, 30 July 2008 (UTC)

Moved

I've moved the article to the full name, Cosmic Background Explorer (COBE), and fixed all double redirects, as well as checked all current redirects. The reason for doing this is that when mentioning COBE in any article, it should always be fully spelled out, (Cosmic Background Explorer (COBE) ) with the acronym following, per the Manual of style, and the initial mention should be Wiki-linked. Therefore, the full spelling should be the primary article, and the acronym be a redirect. Cheers! ^Ariel♥Gold 21:41, 29 August 2007 (UTC)