Bức xạ mặt trời, cùng với tài nguyên thứ cấp của năng lượng mặt trời như sức gió và sức sóng, sức nước và sinh khối, làm thành hầu hết năng lượng tái tạo có sẵn trên trái đất. Chỉ có một phần rất nhỏ của năng lượng mặt trời có sẵn được sử dụng. | Eye of the Beholder 9 places where the hydro-schemes have been sited would hardly complain that the scenery is tarnished by their presence. Some might think that a few of the Scottish dams actually add to the grandeur of their location. On the other hand a zealot for wilderness might see only man-made artefacts that are polluting the landscape but this would be an extreme view. The concept of wilderness is becoming increasingly difficult to promote in today s world which has become highly sculpted and modified by mankind in order to support a population that has rapidly outgrown the ability of the planet to sustain it naturally. Wilderness is where modern human beings have never been and where their presence on the planet is not apparent. Where on Earth is that When one sees photographs of remote mountains remote islands and even very remote seemingly pristine Antarctica showing evidence of contamination originating from human activity it is clear that humanity s flawed stewardship of the planet has resulted in there being really nowhere left where it is possible to view truly unsullied landscape or seascape. James Lovelock the renowned originator of the Gaia hypothesis who was a young man in the 1940s has cogently opined that Even in my lifetime the world has shrunk from one that was vast enough to make exploration an adventure and included many distant places where no one had ever trod. Now it has become an almost endless city embedded in an intensive but tame and predictable agriculture. Soon it may revert to a great wilderness again. In making the above observations it is difficult as a scientist not to be reminded of a rather famous experiment created by John B. Calhoun 15 . It has since been widely referred to as the mouse universe. In July of 1968 four pairs of mice were introduced into this Utopian universe - at least for mice. The universe was a 3 m square metal pen with m high sides. Each side had four groups of four vertical wire mesh tunnels .
