Hi, Paul. First, let me say I appreciate that your comment was not directed at me personally. My intention was to find some information along the lines of what you had spoken about and I happened to have heard such things before.
You do raise some interesting points. I agree with you that 1 Corinthians 2:9 is not primarily about heaven, but about the grace of God. Many Christians have the idea that it is describing the afterlife because they have heard it used so many times in funerals.
You say we aren't "using" those extra dimensions, if they exist. That would be hard to say conclusively. In the first place, I'm not sure the final verdict is in yet on the question. It's a model, and models have fallen apart before with the discovery of new evidence. But for the sake of discussion, let's say there are extra curled up dimensions of space. To say we're not "using" them is also unprovable. I can't say conclusively that string theory is correct. Maybe life IS but a dream? No matter how far down the chain you go, the question still remains: What's the next link made of?
I still think my analogy of the hidden code behind what you see on the computer is valid. If you aren't a computer programmer, you might not understand the comparison. However, surely you could understand that you wouldn't want to rip the guts out of a television and expect it to work, claiming you "aren't using" those parts you don't see on the surface?
Genetic scientists were proclaiming we had a lot of "junk DNA" in our bodies. Lately, they're discovering it wasn't "junk" after all. They just didn't know what it did.
I also agree with you that there is a difference between a dimension and a realm. To be precise, a dimension is a direction. It can be confusing when people speak of other places, such as the spirit world, as being a "dimension." Yet, that is a popular usage of the term and we can't take it out of the dictionary; we can only clarify what we mean by the word.
I would agree that heaven also has length, width, height, and time. I can imagine God transcending time, as well as the any other physical properties. We may experience time differently in heaven, or have no awareness of its passing. But as far as I can tell, we will not live in a timeless mode of existence. One thing will still follow another.
You should not lump all the scientists together. Yes, I thoroughly reject evolution as a pseudo-science and consider it a philosophy wrapped up in scientific language. Many scientists are committed to naturalism and do not believe in God. But science still can tell us things about the universe if it is empirical and not just theoretical. Empirical science is that which can be measured, tested, counted and duplicated. It is not the "what if" brand of thinking we so often are told is "scientific." And if some of those scientists are atheists, it doesn't mean they don't know their field.
I think I've addressed the perceived lack of need for extra dimensions adequately. You ask, if they exist, what would they be?
Space is so vast. Unimaginably vast, isn't it? Yet somehow heavenly beings traverse the distance between here and there quickly. They might utilize those extra dimensions in ways we cannot fathom. I really don't know, so I'll leave it at that.
You should realize the Flatland visualization was mostly an analogy. A 4D cube is called a Tesseract. I will accept your assessment that you have never seen one outside of a computer animation.
You ask, "[I]f these other dimension existed should we have run into a 4D object by now??"
How do you know we haven't? It would appear as something unidentifiable and foreign to our understanding of how objects behave. Perhaps it would even be flying. Sort of like an unidentified flying object...
That's not an endorsement. That is an observation that spirit beings, both of God and otherwise, may be making use of properties of reality which are at present closed off to us. I suspect our glorified bodies will overcome those barriers as well.