From *PBS:*

Could the Universe Be Lopsided?

Physicists call a universe that appears roughly similar in all directions “isotropic.” Because the geometry of spacetime is shaped by the distribution of matter and energy, an isotropic universe must posses a geometric structure that looks the same in all directions as well. The only three such possibilities for three-dimensional spaces are positively curved (the surface of a hypersphere, like a beach ball but in a higher dimension), negatively curved (the surface of a hyperboloid, shaped like a saddle or potato chip), or flat. Russian physicist Alexander Friedmann, Belgian cleric and mathematician Georges Lemaître and others incorporated these three geometries into some of the first cosmological solutions of Einstein’s equations. (By solutions, we mean mathematical descriptions of how the three spatial dimensions of the universe behave over time, given the type of geometry and the distribution of matter and energy.) Supplemented by the work of American physicist Howard Robertson and British mathematician Arthur Walker, this class of isotropic solutions has become the standard for descriptions of the universe in the Big Bang theory.

However, in 1921 Edward Kasner—best known for his coining of the term “Googol” for the number 1 followed by 100 zeroes—demonstrated that there was another class of solutions to Einstein’s equations: anisotropic, or “lopsided,” solutions.

Known as the Kasner solutions, these cosmic models describe a universe that expands in two directions while contracting in the third.

Then there is the Mixmaster Universe (no, really), the Axis of Evil, and tilted universes.

Even if the preponderance of evidence today points to cosmic regularity, who knows when a new discovery might call that into question, and compel cosmologists to dust off alternative ideas. More.

Actually, the best evidence is that the universe is shaped like a leprechaun’s hat. I have equations; they just don’t make any sense.

But, according to one of the above theories (Mixmaster), the universe exhibits “deterministic chaos.” Which means that my equations may not have to make sense.

In other words, as long as it’s fun, it’s fine. But when people start to take this stuff very seriously, they underestimate the storm they are unleashing.

*See also:*

In search of a road to reality

The bill arrives for cosmology’s free lunch

If ID theorists are right, how should we study nature?