We (the USA) have had the ability to fly anywhere in the solar system in a short period of time, since the 1960s. We have decided against doing so for obscure reasons. Any of the hurdles regarding the actual "rocket" and its acceleration could be overcome rather easily. Things that might not be overcome so easily, are high-speed impacts with objects (even tiny pebbles) in space. Further development of our old science (which was abandoned in the '60s), could have made the stars available to us back then. See To the stars by atom bomb: The incredible tale of the top secret Orion Project - https://newatlas.com/orion-project-atom-bomb-spaceship/49454/.
Combining the above with the below discoveries, we could surely reach the stars rather easily. Faster than light could be achieved, thereby sending us back into time as well as reaching the stars faster. With regard to the time distortions experienced by high-speed (Einstein's relativity), faster than light could bring us back to previous times so that we would not outlive the people we left behind on Earth.
The Speed Of Light May Soon Be Possible Through A New ThrusterThe concept of interstellar expeditions has been of particular interest, thanks to the Star Trek movies and series. New discoveries seem to bring us closer to the reality that travelling through the speed of light may soon be a reality. Or so we want to believe. Just imagine, if man sent its fastest space probe to the nearest reachable star, Alpha Centauri, it would take tens of thousands of years to get there. Really mathematically daunting actually. Having said this, most scientists believe that interstellar travel won't happen in the next several centuries. The galaxies in the universe are so ridiculously vast, it is hard to imagine such a theory.
But, it has never stopped some scientists from exploring the possibilities. Recently, a number of advanced models of propulsion have come about, fusion engines, ion thrusters, light sails pushed by lasers, wormholes, and even hydrogen bombs, have made the concept of interstellar travel a bit more possible.
The latest theory is from a physics professor emeritus at Fullerton, Jim Woodward, who has proposed a Mach-effect gravitational assist ( MEGA) drive. Strange as it may sound, Woodward submits that his drive could slowly accelerate with the help of a propulsion system powered by electricity, not combustible fuel. It is based on a disputable sub-component to Einstein's general relativity, the principle holds that the inertia is directly tied to gravity – and in theory, clears the way for " propellantless propulsion."
If you don't mind some scientific jargon, a stack of piezoelectric crystals generates the thrust, by storing small amounts of energy and vibrate when electrified. The synchronization of tens of thousands of vibrations per second produces physical momentum.Woodward calls these crystals "gizmos", and explains that the changes in mass or "Mach effects" will slowly but surely accelerate to incredible speeds. His followers describe it as "rowing a boat on the ocean of spacetime."