I’m not an expert cosmologist, nor even a physicist. And as someone already said in a comment in the thread that posed me the above question, few people in such threads are actually experts.
[Aside: I’ve probably 120 posts over 14 years on this blog alone highlighting sources of doubt – eg arising from CMBR evidence – not all of them empirical, as I say. My previous post includes links to 3 other posts which themselves include links to many more. But let’s address the one doubt here before we unpick the whole story:]
As soon as you get into the area of some specialised theory within the domain, the maths becomes even more specialised. And even if interlocutors were sufficiently expert in any objective sense, conducting a sufficiently nuanced dialogue in such an environment within which neither has any history of mutual respect and understanding of the other in the subject matter is pretty risky anyway.
The request was actually for “empirical” evidence. A pretty tall order at the extremes of the known and knowable cosmos, where pretty much all evidence is indirect. But here goes:
The simplest starting point of empirical doubt for me is the apparent CMBR alignment with the ecliptic of our home solar system. Of which Larry Krauss said back in 2006:
[T]here appears to be energy of empty space that isn’t zero! This flies in the face of all conventional wisdom in theoretical particle physics. It is the most profound shift in thinking, perhaps the most profound puzzle … … when we look out at the universe, there doesn’t seem to be enough structure — not as much as inflation would predict … … when you look at CMB (Cosmic Microwave Background) map, you also see that the structure that is observed, is in fact, in a weird way, correlated with the plane of the earth around the sun. Is this Copernicus coming back to haunt us? That’s crazy. We’re looking out at the whole universe. There’s no way there should be a correlation of structure with our motion of the earth around the sun — the plane of the earth around the sun — the ecliptic … … telling us that all of science is wrong and we’re the center of the universe, or maybe the data is simply incorrect, or … maybe there’s something wrong with our theories on the larger scales.
Larry has never responded to my later questions as what later evidence or interpretation has explained that “crazy” observation, or removed the suggestion of doubt “maybe there’s something wrong with our theories”. (And Larry has of course suffered the slings and arrows of those accusing him of actual “geocentrism” – much amusement and defensive arguments against the spurious accusation of course – but never any sign of Larry actually addressing his own original point.)
I could stop there for now. But it’s important to note that for me the above is simply an observation confirming existing doubt. Doubt arrived at by other non-empirical philosophical, logical and theoretical arguments. And also to note that there are several other reported observations looking for missing “mass” and “echoes” of energetic events in the boundary conditions of the cosmos, and the inflationary processes since in what we can observe now, which cast doubt on the theory.
As I’ve concluded before reasons the doubts are downplayed are political, in a climate where to concede an inch risks headlines proclaiming the opposite. Like the hyped article that initiated the thread which raised the question at the head of this post, itself a response to a hyped original claim. [For more, see the links in the aside above.]