A very good article from Space.com - https://www.space.com/33306-how-does-the-universe-expand-faster-than-light.html
At some point, at some obscene distance, the speed tips over the scales and exceeds the speed of light, all from the natural, regular expansion of space.
In order to better understand the idea that I am trying present, visual aids are always best.
1. The ship is traveling at normal velocities associated with an Apollo era command module traveling towards the moon.
2. As the ship increases velocity towards light speed it encounters more and atoms, more specifically metallic based atoms that add mass to the ship not physically but externally are encountered.
3. Travelling faster and faster the ship becomes entangled with even more metallic atoms as the ever expanding energy exchange between the ship and the metallic atoms increases exponentially thus adding more mass than the ship is able to over come with its own engines.
4. Much the same way that light cannot escape a black hole,the ship traveling close to the speed of light and faster will not be able to reach the speed of light as the velocity of at the speed of light that the ship is traveling has created its own black hole if you will. Not an actual black hole that consumes everything in its path but an energy consumption similar to a black hole that no matter how much energy you dump into the engines for thrust to try and travel faster, the closer to the speed of light that you travel causes more constriction on the ship. Much like an Anaconda constricts more and more as the prey struggles to get free. Once the prey has been crushed the Anaconda relaxes its constriction.
In this case once the ship starts to slow its velocity the energy transfer between the ship and metallic atoms lessens as the transfer rate and distance of energy between the ship and metallic atoms becomes less and fewer metallic atoms are present.
Its almost as if the energy transfer and distance of the energy transfer traveled is creating an event horizon that cannot be reached as the metallic atoms of the Universe are constricting the ship from all directions. An is opposite of the black hole's event horizon that cannot be escaped from no matter how much energy is dumped into the engines.
No matter how fast you travel towards light speed your mass increases based on the amount of thrust you are using that cannot overcome the mass applied from external metallic atom interactions.
No matter how fast you travel away from a black hole your mass increases based on the amount of metallic atoms present in the black hole applying an external field that cannot be overcome.
5. But if a reverse process of the Higgs-Boson field can be applied that renders the heaviest metallic atoms without mass at all, then the energy transfer and distance of energy transfer between metallic atoms is reduced allowing a ship to travel faster and closer to the speed of light using less fuel and exhaust thrust. Quantum gravity should however keep the atoms of the ship intact while traveling close to the speed of light and faster.
This idea is based on the proven theory that right after the Big Bang occurred that the expanding Universe traveled faster than the speed of light. It wasn't until metallic atoms gain mass that the expanding Universe slowed down considerably. So like I stated, if science can determine when the Higgs-Boson came into being after the Big Bang to add mass to other atoms then process of coupling the mass generation of the Higgs-Boson can be reversed engineered to strip mass away from metallic atoms to allow a ship to travel close to and past the speed of light.
Achieving light speed velocities requires an infinite power source. The only infinite power source available in the Universe is space itself. Space, not used as a power source, but as a medium of lessened metallic atoms that allows for light speed travel.