Researchers analyzed the background radiation left over from the Big Bang to put an end to a long standing debate: Is our Universe expanding the same in all directions, or does this vary depending on where you look?
Finding out if our Universe is a homogeneous body or not is a really important topic in physics. A lot of really heavy-duty math hinges on us knowing this bit of information — mathematical systems such as Einstein’s field equations (EFE,) a set of 10 equations in his theory of relativity that explain the behavior of gravitation as space-time gets distorted by energy or matter.
A team from the University College London analyzed the cosmic microwave background (CMB,) the left-over radiation from the Big Bang, to find out just that. They found that there isn’t any preferential direction of expansion and the Universe just pushes out evenly all over. This goes along nicely with our current cosmological models — but throws a wrench into the mathematical systems behind EFE.
There’s basically two ways our Universe can behave. Either it is homogeneous and isotropic, meaning that its properties are the same no matter which directions you measure them in, or anisotropic, when these properties vary with the direction you measure them in.
Let’s start from a small scale example. On an molecular level, graphite is made up of layers of carbon atoms one on top of the other — kind of like a sandwich. If you apply an electrical current parallel to these layers — along the slices of bread — it’s a really good conductor, because there’s nothing to stop electrons from flowing freely. But if you run the current perpendicular to the layers — through the slices — it’s roughly 20 times more resistant. So its resistivity to electrical current is dependent on which direction you measure it — this is anisotropy.
Certain observations lend weight to the theory that the Universe might be anisotropic — matter, for instance, isn’t evenly distributed throughout it. Star systems, galaxies, and galaxy clusters are clumps of matter seemingly randomly thrown about the Universe, and some researchers have suggested that this caused by some kind of force or directional flow has pushing them into position.
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