The Universe appears to have a value of #Omega# very close to #1#. This means the internal angles of a triangle add to #180^@# which is very odd, because it is far more likely that there will be an excess of mass-energy in the Universe (meaning #Omega# would be greater than #1# and the internal angles #<180^@#) or too low an energy density, meaning #Omega <1# and the internal angles #>180^@#.
It's just weird that it is so very close to #1#, with no a priori reason for it having this value. Cosmologists, feeling honest, accept it's a bit embarrassing.
The Wikipedia article https://en.m.wikipedia.org/wiki/Flatness_problem is excellent.
