Science's journey into the future is being delayed. A global attempt to create nuclear fusion is being threatened by rising costs and technical challenges. The ITER project was set up in 2006 by the U.S. and other countries to build an experimental nuclear fusion reactor in the south of France. But the weak economy might mean that fusion as a source of commercial power is at least a hundred years away. BBC science correspondent Matt McGrath joins us with more.
For an explanation of nuclear fusion, watch the video below.