So, hard hard hard sci fi. Hmmm. Fred Pohl is your huckleberry. Try The Heechee Saga.
Lois McMaster Bujold is pretty faithful to physics, give or take FTL. the Vorkosigan Saga should keep you busy. If you wanna go old school, start with Falling Free.
Niven does a pretty good job, too, at least if you keep out of Known Space. The Fifthp in Footfall abide by the laws of physics, and Niven and Pournelle throw project Orion in there for good measure (long before it was cool to do so). Despite the fact that it is a series utterly devoid of space ships, The Integral Trees and its sequel The Smoke Ring are heavily reliant on physics.
Richard K Morgan also doesn't fuck around, although he's hit or miss in my mind. Thirteen was great; Altered Carbon was okay.