Certainly, microwaves would work: a test carried out in 2008 transmitted useful amounts of microwave energy between two Hawaiian islands 148km (92 miles) apart, so penetrating the 100km of the atmosphere would be a doddle.

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The news is not surprising - it is already well established that bacteria can be transmitted this way - but the focus on MRSA bacteria has prompted calls for further work to establish how significant this could be in the fight against hospital infections.

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The hopeful news Dr Bearman's work brings is that it should be easier to stop the spread of sexually transmitted diseases through a teenage-type graph than an adult one, since the spindly chains of connection between individuals can more easily be broken.

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