Is the Universe Symmetrical?
The Universe as a Whole
When you look up at the night sky, you see stars going on for what seems like infinity. To try to imagine how it all is arranged seems like a Herculean task if ever there was one. We are limited to our place in the heavens and so only have a limited amount of data we can work with. What overall details of the universe's structure can we make out, if any? What symmetry lies in the universe?
Large Scale Versus Small Scale
One consideration that must be made when talking about the symmetry of the universe is how we look at it. If we examine it on a small scale, we will see much disorder. Planets, asteroids, comets, and other debris orbit stars, which are themselves part of clusters, which form galaxies which are also clustered together. Looking at these structures, we would feel that no way could there be an underlying pattern to it all. It is not unlike looking at the horizon of the Earth and seeing how jagged it is with mountains and trees, but the more we increase the scope of our view, those irregularities smooth out and that flat horizon becomes more and more curved until, from a distance, the Earth is a sphere.
The universe is similar to this analogy, where it is just a matter of perspective that defines what is chaos and what is a pattern. All those clusters of galaxies do follow a shape that looks much like parts of a spider-web. Galaxies are connected through clusters of dark matter, a strange substance which cannot be seen but can be measured through its interactions with gravity. The large scale can reveal patterns not seen on the micro-scale. The further we increase the scope of our viewing, we see more and more of this spider-web pattern appears to consolidate into a general form. But why?
Inflation and the CMWB
In the 1960s, it was discovered that a general blanket of microwaves seems to originate from everywhere in the sky. It was found that these signals were a remnant from the beginnings of the Universe, from when it was about 300,000 years old. They started out as infrared, or heat waves, but through the expansion of the universe they have shifted in the spectrum to become microwaves. In the 1990s, much work was done on this Cosmic Microwave Background (CMB), and eventually a map of all those microwaves came in near the turn of the century. Recently, the Planck spacecraft has returned with an even higher-resolution map of the CMB. What it reveals is striking. The universe seems to be homogeneous, or, that is, consistent throughout. This seems counter-intuitive to what we would expect, which is a non-uniform distribution on a large scale. The best answer for explaining this result is a theory known as inflation.
If we go back to the beginning of the universe, we start at the Big Bang. This event sparked the growth of all that is around us, and within a few fractions of a second of the universe's existence it underwent what is called the inflationary period. For reasons which are still unclear, the universe expanded much faster that the speed of light (which is legal, because it was space that was expanding). This sudden growth so early in the life of the universe ensured that the material present was distributed rather evenly before any irregularities could become dominant and disrupt any overall geometry. Recently, gravity waves from this event were discovered, a huge boost for the inflation idea.
Not the End of the Story
The CMWB map shows temperature fluctuations of the early universe, to within a fraction of a kelvin. If we compare the average temperature changes over the map, it is rather homogeneous. However, some problems do seem to exist based upon a further look at the map. Astrophysicists can see a general cold spot near the center but not at the center, of the map. Also, some areas seem to have higher temperature fluctuations that do not even out. But the map does have correspondence with the overall distribution of galaxies in the dark matter-made web. So what can we make of this?
If anything, it is that the science behind this is still ongoing, and the implications of an asymmetrical universe are grand. If the universe is flat, as models had suggested, then a symmetry should exist and we will go through further expansion due to dark energy. However, these new findings imply a possible curvature to the universe. New models of the universe will need to be defined, and perhaps our notion of a symmetrical universe will need to be redefined though that process.
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© 2013 Leonard Kelley