Kennan, whose writings gave birth to the theory of nuclear deterrence, argued passionately but futilely against the development of the hydrogen bomb.

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Before his writings on the carbon cycle, Mr Bethe produced several papers that endeavoured to pull together the whole theory of nuclear physics.

ECONOMIST: Hans Bethe, nuclear physicist, died on March 6th, aged 98

Nuclear fusion power plants, in theory, can provide clean, safe, cheap and ubiquitous power.

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They are the only nations that both possess nuclear weapons and are large enough, in theory, to absorb a first strike and live to retaliate.

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The theory is that by so doing, other nations will be deterred from conducting nuclear tests or otherwise embarking upon nuclear weapons programs.

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Theory suggests that a certain type of giant, short-lived star can experience catastrophic collapse when the nuclear reactions at its core can no longer support its mass.

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