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Articles: Devotion | Quest for Infinity - 08
- Prof. venkata ramanamurty mallajosyula
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In the beginning, matter [such as it was at that time] and radiation were tightly coupled with the result that the Universe was opaque. In other words matter was like a fog that prevented light from being propagated freely. When the Universe was about 300,000 years old, radiation and matter became decoupled. Thereafter, the Universe became transparent, allowing radiation to propagate freely – this is like a fog lifting, allowing light to be propagated freely. Radiation then began to fill the Universe, and even as the Universe expanded, the temperature of the radiation also began to fall. This radiation, which now fills the whole of the Universe, is what we refer to as the Cosmic Microwave Background or CMB for short.
What Went Bang?
How do we know all this? Largely through studies of the CMB. In recent years, the CMB has been the focus of intense studies, and I shall soon refer to some of them. But first, I would like to address the question that has been sometimes asked: “What was it that banged?” This is a sort of rhetorical way of asking some sharp questions about the so-called Big Bang.
You will recall that when the CMB was first discovered it was found that it was isotropic, that is to say, the same intensity was found when the observing telescope was pointed in different directions. True, some minute fluctuations were discovered later on – and these fluctuations, by the way, are very important for the consequences they produce! – but, the fact is that by and large, CMB is uncomfortably homogenous and uniform. How come? Now why one earth should that be a problem? Because, of one important technical hitch called the horizon problem.
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