When we observe the world around us, we do this using our senses in connection with our brain which leads to our awareness and our consciousness in space and time. This consciousness has always been bound by nature to each person. That consciousness is always in the middle of the surrounding world and has been used first when we try to orientate ourselves: where are we. So in earlier days everybody knew that the sun is going to come up and turn around through the sky; this was an ordinary experience for each individual; everyone observed that the sun rises up and goes down. When a broadly accepted idea was thrown away by various discoveries and calculations then it takes some time before this new interpretation is accepted. In the history we did find out that our daily experience was not the truth at all because we did not have a clear point of view and explanation, whereas people saw themselves at the center of the surrounding world. The most important apparatus for recording the human conscience is stipulated by the possibilities that offer the senses among other things by the capacity to SEE. With our eyes we can observe only electromagnetic waves of around 5000 Angstrom. We could change our consciousness in space and time however considerably because we start to use other recording equipment, by which nearly the whole electromagnetic spectrum can be converted into perceptible information (like infra-red photography, radio telescopy). As a result, our consciousness seems to become gradually more flexible in accepting the facts, that reduce our favored central position in the universe increasingly.
While hundreds, even thousands, of scientists study the various branches of quantum theory and apply it in many, many fields of experimental research, only a few persist in devoting their time and passion to further development in the study of gravitation. Can it be that empty space is simpler than material bodies. Gamow.
See an overview of theories at the button page 5.3.