How do observations of the cosmic microwave background radiation tell us about the composition of the universe
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In 1965 two American physicists at the Bell Telephone Laboratories in New Jersey, Arno Penzias and Robert Wilson, were testing a very sensitive microwave detector. (Microwaves are just like light waves, but with a wavelength of around a centimeter.) Penzias and Wilson were worried when they found that their detector was picking up more noise than it ought to. The noise did not appear to be coming from any particular direction. First they discovered bird droppings in their detector and checked for other possible malfunctions, but soon ruled these out. They knew that any noise from within the atmosphere would be stronger when the detector was not pointing straight up than when it was, because light rays travel through much more atmosphere when received from near the horizon than when received from directly overhead. The extra noise was the same whichever direction the detector was pointed, so it must come from outside the atmosphere. It was also the same day and night and throughout the year, even though the earth was rotating on its axis and orbiting around the sun. This showed that the radiation must come from beyond the Solar System, and even from beyond the galaxy, as otherwise it would vary as the movement of earth pointed the detector in different directions.
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In an extention of the big bang theory, the size of the spots in the microwave background radiation can indicate the geometry of the universe. Recent (2001) measurements confirm that the universe is "flat" (for an explanation of shapes, see source link). There is a 2% margin of error in this measurement.\n\nAs for what is beyond space, I would say the question isn't possible to answer, as most people define "space" to mean "Everything there is". What is outside of "everything"? Nothing, it would seem.
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There are quite a lot relationships. Here are a few examples:\n\nLet´s start close at home.\nThe sun, as well as all the other stars, fuse hydrogen into helium atoms. The first step is a reaction that takes place due to the weak nuclear force: two protons fuse into heavy hydrogen, liberating an electron and a neutrino.\n\nExploding supernovae liberate a large amount of energy in the form of neutrino´s. \n\nOn a much larger scale, the Big Bang theory predicts a few things related to  subatomic particles.  The observed abundance of hydrogen, helium and some other light elements produced just after the Big Bang confirms to the calculations. The latter use reaction data from subatomic reactions.\n\nFurthermore the universe is filled with a sea of radiation at a temperature of just over 2.7 degrees Kelvin, the remnant of the superhot radiation from the fireball that has cooled down as the universe expanded. This radiation originated by the reaction pn->d gamma a few minutes after the Big Bang
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The CMBR is not in the past. It is here now. \n\nThe cosmic microwave background is a prediction of Big Bang theory. In the theory, the early universe was made up of a hot plasma of photons, electrons and baryons. The photons were constantly interacting with the plasma through Thomson scattering. As the universe expanded, adiabatic cooling (of which the cosmological redshift is an on-going symptom) caused the plasma to cool until it became favourable for electrons to combine with protons and form hydrogen atoms. This happened at around 3,000 K or when the universe was approximately 380,000 years old (z=1088). At this point, the photons did not scatter off of the now neutral atoms and began to travel freely through space. This process is called recombination or decoupling (referring to electrons combining with nuclei and to the decoupling of matter and radiation respectively).\n\nThe photons have continued cooling ever since; they have now reached 2.725 K and their temperature will continue to drop as long as the universe continues expanding. Accordingly, the radiation from the sky we measure today comes from a spherical surface, called the surface of last scattering, from which the photons that decoupled from interaction with matter in the early universe, 13.7 billion years (13.7 G yr) ago, are just now reaching observers on Earth. The big bang suggests that the cosmic microwave background fills all of observable space, and that most of the radiation energy in the universe is in the cosmic microwave background, which makes up a fraction of roughly 5×10-5 of the total density of the universe.
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According to the world's best brains(Scientists) 80% of the universe is dark matter(read unknown). So it will take ages before we get any idea to your question.
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Assuming the universe to be a perfect system expanding adiabatically post big bang, you can determine when the average temperature in the universe was cooler than the temperature required for nucleosynthesis, then take the difference between the times.  Or, from Wikipedia, "...at three minutes after the Big Bang, the universe becomes too cool for any nuclear fusion to occur."  There ya go.\n\nHowever, http://www.scienceandreason.net/oq/oq-co008.htm#history is contrary to wikipedia.  Surprise....
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(13.7 +/- 0.2) billion years, according to the most recent data from the WMAP probe, studying cosmic background radiation
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The age of the universe from the time of the Big Bang, was estimated to be about 13.7 billion (13.7 × 109) years, with a margin of error of about 1 % (± 200 million years), according to NASA's WMAP (Wilkinson Microwave Anisotropy Probe)
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http://www.seds.org/messier/m/m031.html
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The content of the Universe is widely thought to consist of three types of substance: normal matter, dark matter and dark energy.\n \nNormal matter consists of the atoms that make up stars, planets, human beings and every other visible object in the Universe. As humbling as it sounds, normal matter almost certainly accounts for the smallest proportion of the Universe, somewhere between 1% and 10%.  \n \nThe more astronomers observed the Universe, the more matter they needed to find to explain it all. This matter could not be made of normal atoms, however, otherwise there would be more stars and galaxies to be seen. Instead, they coined the term ‘dark matter’ for this peculiar substance precisely because it escapes our detection. \nAt the same time, physicists trying to further the understanding of the forces of nature were starting to believe that new and exotic particles of matter must be abundant in the Universe. \n \n \nThese would hardly ever interact with normal matter and many now believe that these particles are the dark matter. At the present time, even though many experiments are underway to detect dark matter particles, none have been successful. Nevertheless, astronomers still believe that somewhere between 30% and 99% of the Universe may consist of dark matter.\n \n \nDark energy is the latest addition to the contents of the Universe. Originally, Albert Einstein introduced the idea of an all-pervading ‘cosmic energy’; before he knew that the Universe is expanding. The expanding Universe did not need a ‘cosmological constant’ as Einstein had called his energy. \n\nHowever, in the 1990s observations of exploding stars in the distant Universe suggested that the Universe was not just expanding but accelerating as well. The only way to explain this was to reintroduce Einstein’s cosmic energy in a slightly altered form, called ‘dark energy’. No one knows what the dark energy might be. \n\nIn the currently popular ‘concordance model’ of the Universe, 70% of the cosmos is thought to be dark energy, 25% dark matter and 5% normal matter.
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Well you can use spectroscopy to find out the composition of distant objects in space.  IE if a star emits light near (usually a slight red shift from distant objects) the emission lines of helium or mercury you could conclude that those elements are present.\n\nMike
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The observable universe is estimated to contain:\n10^11 galaxies, 10^21 stars, and 10^78 atoms.\n\nThe means 100,000,000,000 galaxies.
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We can see the cosmic background radiation. Contrary to what many would say this is not the big bang itself, but the moment the first atoms formed (when protons bonded with electrons) and photons of light could freely travel through space. This happend about 300,000 years AFTER the big bang. The universe was about the size of the Milky Way Galaxy at that time.\n\nWe cannot see before this moment in time. Before this, information in the form of photons could not propagate. The actual moment of the big bang will forever be beyond reach.
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Hi bornsmartgal\n\nOther possible explanations for the observations which support big bang theory are numerous.  They tend to focus on trying to explain the redshift observations, and they include tired light, strange compton scattering, large hydrogen clouds, etc.  The thing is that no single explanation (other than big bang theory) explains *all* the observations.  For example very few of them explain the time dilation of distant supernovas.  There's also the Tolman surface brightness test which distinguishes between big bang models and other models by a factor of z^4 (this is a nice test because it gives a very large discrepancy).  Only an expanding universe passes the test.\n\n\nHope this helps!\nThe Chicken
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In physical cosmology, the Big Bang is the scientific theory that the universe emerged from a tremendously dense and hot state about 13.7 billion years ago
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a. emission lines from reference elemnts on Earth
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It is a chart used to map the general features of the universe, made by a cosmologist