Just because you are an astrophysicist doesn't mean you know anything about the shape of the Earth. You observe the stars, right? Not Earth -- stars. So how can you tell such a story? It's just a bunch of assumptions. If you truly were a proper scientist you would understand that. You don't know how the universe operates, stop making dumb assumptions.
What if the universe is surrounded by Earth and the farther away from earth you go the smaller you shrink? Yeah it may sound weird to us due to our expectation bias brainwashed into us by the public education but it is a possibility. And guess what, ALL THE MATH WOULD STILL WORK OUT. You could still do your astrophysics and you wouldn't see a difference. Come one, did I really have to tell you this? Why is it that you cannot come to the same conclusion on your own? This is how strictly you are thinking INSIDE THE BOX.
I'll ignore the ad hominem attack. Instead, let's ask the following question:
What problem does the concave Earth theory solve? A new theory is usually developed if there is a problem with the current theories. Subsequently, that new theory needs to make a
testable prediction, preferably one that is different from the established science.
I have not even seen a reason why we would need a concave Earth theory in the first place. Nothing convincing I mean. There is nothing wrong with the understanding that the Earth is a ball-like planet. Trust me, there are many very smart outside of the box thinkers that happen to be scientists out there. With wild ideas that still make sense, both mathematically and conceptually. The concave Earth theory does not fall in that category.
For fun, test yourself. Google "are you a quack", and read the first hit (by Warren Siegel). I actually have gotten quite a few emails with theories of people that I have to refer to this...
Enough though. I'll go on mute again for a few years...