After tragedy strikes Sheldon he becomes reacquainted with someone from his past. In this TBBT universe Sheldon and Amy get married at the end of season 11 but do not win the Nobel Prize at the end of season 12. Part 8, epilogue.
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By the end of the 2020s Superasymmetry was no longer the hottest new topic in Physics. Great progress had been made in Grand Unified Theory of Everything, the 2029 Nobel Prize had gone to some Japanese theoreticians for their work in this field. Sheldon and Leslie continued with their work in Superasymmetry but all the Nobel Prize talk has died away.
Then one night in October 2030 Sheldon and Leslie were woken by both of their phones ringing at the same time!
Leslie turned on the bedroom light to look at her phone.
"Who on earth is calling at 3.00am?"
Sheldon looked at the area code for the number calling his phone and said to his wife
"Who in Sweden is calling at 3.00am..."