The European Space Agency's Planck satellite is due to launch from French Guiana on May 14th. Pending a successful deployment, Planck will measure the temperature of the cosmic microwave background radiation (CMBR) across the entire celestial sphere, with greater sensitivity and spatial resolution than achieved by its predecessor, NASA's WMAP satellite. The variations in the temperature of the CMBR reflect variations in the density of matter when the universe was 380,000 years old, at the time of so-called 'recombination' when atomic nuclei captured previously free electrons. New Scientist duly have an article to herald the launch, which claims that "these so-called anisotropies are believed to be due to inflation...During inflation, quantum fluctuations in space-time were extended to cosmological scales: by the time the CMB was released, these fluctuations had led to variations in the distribution of matter across the universe. Denser regions of the universe produced CMB photons slightly colder than average, and vice versa."
In fact, whilst it is claimed by cosmologists that temperature fluctuations more than a few degrees across are the imprint of fluctuations present at the end of the inflationary period, fluctuations smaller than a degree are believed to be the result of acoustic oscillations in the plasma of baryons, electrons and photons present between the end of inflation and the time of recombination. These small-scale fluctuations are therefore the visible remnant of the earliest sound waves in the universe.
For the large angular-scale fluctuations, the denser regions redshifted the light climbing out of those regions, and therefore produce cooler spots in the CMBR; in contrast, for the small angular-scale fluctuations, denser regions were regions where the plasma was hotter, hence these denser regions produce hotter spots in the CMBR.
10 comments:
All well and good Gordon, but what went bang is the question us mere mortals want to know :0)
Nothing went bang!
So describe nothing to me.
..or a better question, what is the nature of "nothing" and what are the rules to make nothing suddenly something (noble in the post if you can answer correctly...which no one knows is correct anyway)
My own answer would be "potential" but that brings it all down to odds.But something must have an effect on the nothing..must it?
In fact, I don't subscribe to those interpretations of quantum cosmology which suggest that there was, or could have been, a transition from nothing to something.
If you're interested, you could try reading between the equations in my paper on the concept of creation in inflation and quantum cosmology.
I'd be interested in what you think Planck could tell us about the theory of the multiverse. I've heard the scientists doing their PR bit suggesting it could provide evidence, to do with things like the curvature of the cosmos. My understanding is that this evidence would not be direct but circumstantial, and always open to other interpretations.
Try I did Gordon, but the ale won out in the end :0)
And am I correct in saying the universe is not expanding at all, but stretching what is already in the universe?
Now filling a swimming pool up with custard and running across it, is proper science, no conjecture about that.
Planck will certainly provide evidence relevant to properties such as the curvature of space, Mark. However, science operates within a hypothetico-deductive-Bayesian framework, and cosmology is no exception here. When new evidence is accumulated, it changes the probabilities of certain theoretical propositions. Even after Planck, there will be a variety of theoretical models consistent with the data, but the relative probabilities will have changed.
Never mix ale and cosmology, Sean! The correct interpretation of the expanding models of general relativistic cosmology is that the distances between the points of space is increasing. The increasing distance between galaxy clusters is not due to the motion of matter within space.
I've been wondering what the universal music would actually sound like. Probably something along the lines of "In The Court of The Crimson King" by King Crimson.
Yes, that would have been very appropriate. Very proto-Vangelis.
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