Dear Dr. Sahib I'm so happy because of your input! Really I am. Thankyou for your generosity and open-mindedness.
I feel that our eyes can never see the invisible, nor can our brain realize the difference of the seen and the unseen. Only a few centuries ago we were not even able to think about the microscopic life. Being a Doctor you must be familiar with the discovery of the first cell, dead cork cell. With the increased "resolution" now we are able to see the invisibles world through the "Electron Microscope",also. Just want to quote a Hadith here, (I may be wrong)..that when the Prophet SAW said .There's "evil" in "open" food, it might have meant there're "jerms" in open food or "open" food gets contaminated, easily, so cover it up.
Similary, I only want to suggest thatt this world still needs to be explored to understand the "invisible" which we may never find out , in true sense of it's meaning , but we are required to believe in them. Allah's prophet was revealed by many 'unseen' facts otherwise he might have witnessed them by himself + how can we say that the "cavemen" lived at the time of Muhammad SAW?