Verified answer

An atom can't travel at light speed. It can be accelerated to almost light speed, and that takes enormous energy. A human has a lot of atoms. The particle accelerators that can make an atom go that fast don't have to travel with that atom. A big impediment to sending a spaceship to near light speed is that it has to carry the fuel supply. Without a near 100% conversion of matter to energy you either deplete the fuel long before you get anywhere close to light speed, or you have so much fuel to have to accelerate that you have a problem accelerating it. Matter-antimatter? There is no antimatter supply, and the only short-lived antiproteins ever created in the particle accelerators take a lot of electricity to create. Multiply that by the number needed for the spaceship, and it is more electricity than the whole world produces.

If a technology could be developed to utilize energy from the space environment to accelerate or decelerate the ship, the problem would be solved, but we currently have no clue if or how to do that.

And that still only gives decreased aging during the trip, not actual time travel. Worm holes are just inventions of science fiction writers.

Scientist Ron Mallett is researching it

Yes, When the clocks go back.