What is the biodome? Why is it so challenging for scientists to create a self sustaining biodome that is isolated from the rest of the planet?

A bio dome is a self-contained, self-sustaining, human-made environment. One way to think of it is as an ecosystem built by people. It is difficult to separate bio domes because they exist on this planet. They are a part of our environment, subject to all our natural laws, regardless of what the intentions are of the experiment.