"They would finish their PhD when they have made a difference in the real world." By that metric, most fundamental discoveries in the last 200 years would not

"They would finish their PhD when they have made a difference in the real world." By that metric, most fundamental discoveries in the last 200 years would not have been enough to finish a PhD. Even Hamming's error correcting codes took 10+ years for Bell Labs to implement it. And even then it was because they had no other alternatives and were in a bind.