The Orthogonal series is a sci-fi trilogy by Greg Egan, composed of The Clockwork Rocket, The Eternal Flame, and The Arrows of Time. It is an example of how you can simultaneously be hard sci-fi and violate the laws of physics.
Let's talk about geometry. The Pythagorean theorem tells you a² + b² = c², relating two possible paths you can take through space. Taking a different path increases the distance you need to travel.
Note I said space. What about paths through time? Well, as it turns out, the Pythagorean theorem for time is a² - b² = c². That is, taking a "longer" path reduces time. If you've ever heard of how travelling near the speed of light causes your personal time to be shorter, this is the formalization of why.
What does this have to with a sci-fi novel? Simple.
What if Pythagorean theorem for time was a² + b² = c², just like space? Orthogonal is about such a universe.
This changes physics. There's no universal speed limit. Different wavelengths of light travel at different speeds. Emitting photons causes your energy to increase. And that's only the beginning.
Orthogonal is an exploration of an alternate world. The plot is lacking, but the joy comes from the world. Go read it.