Yes, science is the study of the observable world. But not just our inherent surroundings. We can observe changes in species, we can observe the genetics, and we can observe the fossils. All of these things are clear pieces of evidence for evolution. This is such a desperate question. It almost makes me want to go so far as to label you as "going full retard", but I will simply call you stupid. It may be immature, but that's the only thing I can think of. What next, are you going to start saying dinosaurs never existed because no one was around to see them? Give me a break.