Craig Ferguson had astronomer Derrick Pitts on his show one night. As I listened to him talk, I tried to imagine what it must be like to see the world without consideration for God or destiny or anything beyond living your life and then ceasing to exist. The mere thought depressed me. It must depress a lot of people because even those who aren't religious believe in heaven. We're created to crave immortality! And heaven isn't just something to believe in, as though it may or may not be there. Like the earth being round or the grass being green, I consider heaven the same as anything else. You don't say "I believe in the grass." You don't need to believe in it. Clearly, it's just there, plain as day. But because heaven is not visible to the human eye--a decaying, material thing--its existence is up for debate. The wind, magnetic fields, atoms, particles, gravity, etc.--these are all invisible forces, but because we've managed to study them, they're considered undeniably real. My point in all this is: just because you can't see it or feel it or study it doesn't mean it doesn't exist.
"So was fulfilled what was spoken through the prophet:
'I will open my mouth in parables,
I will utter things hidden since the creation of the world.'" - Matthew 13:35
Maybe God doesn't want heaven to be found. Maybe He deliberately hid it from us, like He has hidden other things.
"Now faith is being sure of what we hope for and certain of what we do not see." -- Hebrews 11:1
Maybe it could be seen with our eyes, but He doesn't want us to see it.
"But Stephen, full of the Holy Spirit, looked up to heaven and saw the glory of God, and Jesus standing at the right hand of God." - Acts 7:55
We have always assumed that humans are incapable of seeing heaven, but clearly it was shown to Stephen. Jesus was resurrected and showed himself to us, and that means invisible things can be seen, but only when God wills.
I was going somewhere with this. I guess it's just that I don't see eternal or spiritual things as separate from material things. If I see a show about space, my mind naturally thinks about heaven. The same can be said about nature shows. It seems lately my whole world is consumed with thoughts of what lies ahead, after this world is done.