The future is always full of surprises (Inside, June 21), but the past teaches us many lessons.
The next decades will be dominated by the rising cost of energy.
Scarce development funds will be directed to more generally useful projects, so that my expectation of the practical possibility of flying to New York in 90 minutes in 2050 is a very confident zero.
PROF RODERICK A SMITH
Institution of Mechanical Engineers
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