“I think two laps of 50 seconds are not out of sight” (Seb Coe, 22 December 1979).
The first runner to break 1.40 for the half mile will cross a boundary as impermeable as the 4 minute mile once seemed. To run it, you would have to run two laps in under 50 seconds each. There are relatively few runners who have the leg speed to manage even one lap at this time.
Step forward David Rudisha. Of the twelve times in history that any runner has broken 1.42, six have been run by Rudisha.
In his last three races before the Olympics, Rudisha ran on each occasion in under 1.42; in the first of them (at New York) he ran a first lap in under 50 seconds; in the second (the Kenyan trials) he ran a last lap in under 50 seconds; in the third (the Diamond League), he was back to an opening lap in sub-50 seconds.
I don’t doubt that Rudisha has broken 1.40 in training; the real question is whether he can do it in open competition?
If he does, then the Olympics deserve to be remembered for his achievement as much as any record that any other athlete breaks.