Steve69 - Of course you are right and of course you are wrong. This is likely not something we are supposed to understand, or rationalise for that matter. Good on you for thinking about it.
Your theory would indeed seem possible. Let's review what we know in 1 and 2 below.
1. the visible universe either to the eye or telescopes never existed at one instant in history in the way it appears at the time you observed it. eg. Many of the stars we see are extinct by the time their light reaches our eyes or telescopes. We see a collage of many things that existed throughout time.
2. everything in the universe is constantly moving and changing, therefore the tests within 39 billion lightyears would be superfluous and unable to prove or disprove this theory as you would never be able to generate a "match" at the instant in time you ran the test. any match the test generated would need to have many more simulation assumptions than your original theory.
If you put 1 and 2 together, I see no evidence that it couldn't be the same stars over and over again, at different points in their history and at different locations in the universe (explaining your reflection) - giving the illusion of an infinitely massive Universe. Then again, we have no evidence that they are indeed the same stars because of Number 2) above so you could be right or you could be wrong...
There was a good reason our ancestors were led to believe by those in power in the existence of God. There's a good reason we are being led to believe the Universe is infinitely large right now.
