For some time Physicists have been patting themselves on the back over the formulation of the theory of Cosmological Inflation. In this theory, in a twinkle of time DURING the Big Bang, the size of the Universe increased exponentially - essentially increasing in size faster than the speed of light.
Then there was evidence supporting this theory that came from space - satellites surveying the CMB (light left over from the Big Bang) found things in the light consistent with Inflation.
And Physicists patted themselves on the back even more.
After all, Inflation explained so much. For example, the homogenous appearance of the Universe no matter where you look.
To MY untrained eye, there are "cold spots" in the CMB and it is NOT homogenous. There are great voids in the Universe and there is a suspected "Great Attractor" that has thousands of galaxies moving off in their own direction at a high rate of speed. But they say it is and what do I know?
Anyway, recent analysis of the CMB seems to indicate that the observations that supported Cosmological Inflation were misinterpreted - the light they saw was actually reflected off dust - you know ... stardust. The kind of stuff that you and I are made of. Anyway, since the light is reflected off of dust, it can't be the kind of light they need to substantiate the Theory.
Their arms are shorter now and it's back to square one.
I love this stuff ... the path not taken.