The man who struggled with his own ideas Charles Darwin's theory of evolution by natural selection made us rethink our place in the world. The idea that humans shared a common ancestor with apes was a challenge to the foundations of western civilisation. Darwin kept silent for 20 years before going public and was only half joking when he described writing his book 'On the Origin of Species' as 'like confessing a murder'. This is the story of one man’s struggle with the most radical idea

Les varetes de control s'utilitzen en reactors nuclears per controlar la taxa de fissió d'urani o plutoni. Les seves composicions inclouen elements químics com el bor, el cadmi, la plata o l'indi,que són capaços d'absorbir molts neutrons sense fissió. Aquests elements tenen diferents seccions transversals de captura de neutrons per a neutrons de diverses energies. Reactors d'aigua bullint (BWR), reactors d'aigua pressuritzada (PWR) i reactors d'aigua pesada (HWR) operen amb neutrons