The Atom Engine or Atom Drive concept.
The atom engine does not imply an engine the size of an atom but rather an engine driven by atoms.
No its not atoms passing through an engine which happens in every type of new and old engine, but the explosion of the atom it self.
See we humans already know what an atom is and how to break it in order to release the energy within but we need a way of using the mentioned energy for a purpose other then destruction.
What the atom drive will finally accomplish is not just using that energy simply for destruction but now also as a means of transport.
That transport only feasible in a non gravity environment much like space.
By way of mechanizing a spring loaded barrier between the ship and the actual detonation of the atom.
You see instead of the explosion pushing the turbine that spins the rotor to spin the wheel, the explosion pushes the piston to simply start the motion, which in the vacuum of space continues until the same force is applied in the opposite direction in order to stop.
What the spring loaded barrier between the explosion and the ship is not only safety from the direct explosion but also the impact of the apposite and equal reaction so it does not feel like a car hit a wall at 200 km/h
I hope that clarifies all you need to know to not only have a sufficient imagination or mental image of the this creation but the shear size of the undertaking and of course the unlimited outcomes of this Atom engine.