What's an insanely fast way of space travel possible in the near future?

NASA is designing an engine that uses heat from a nuclear reactor to heat a propellant and expel it for thrust.

https://www.wired.com/story/nasa-wants-to-send-nuclear-rocke...

https://www.popularmechanics.com/space/moon-mars/a18345717/n...

Tiny light sail spacecraft don't need new physics.

People have talked about going to 0.1 c and to another star that way, but rather if you can send a large number of those past 500 a.u. you can use the Sun's gravitational lens to image continents on planets in other solar systems, watch stars get wrecked by a black hole, and watch other civilization's TV programs.

That same kind of telescope is how you get downlink from the interstellar filmcraft.

Live as a digital copy, travel at the speed of light.