Complex sentence: Sabra received his undergraduate degree at the University of Alexandria, then studied philosophy of science with Karl Popper at the University of London, where he received a Ph.D. in 1955 for a thesis on optics in the 17th century.
Split into simpler sentences: Sabra received his undergraduate degree at the University of Alexandria. He then studied philosophy of science with Karl Popper at the University of London, where he received a Ph.D. in 1955 for a thesis on optics in the 17th century.