A new means of space propulsion... closed loop pulse propulsion... here's the idea

[mikelewis]

20. And as a backup... the same explanation AI style

But why wouldn't the astronaut just stop right in place then?

ChatGPT
The reason the astronaut wouldn't just stop in place when firing the shotgun with curved barrels (which redirect the bullets back towards him) involves the concepts of linear momentum, angular momentum, and the dynamics of the forces involved. Let's clarify why stopping in place doesn't happen in this scenario:

Linear Momentum:

Initially, when the astronaut fires the shotgun, linear momentum is conserved. The explosion propels the bullets forward, and an equal and opposite force propels the astronaut backward. This is the recoil we talked about earlier.
If the bullets are then redirected back towards the astronaut, they will exert a force on the curved barrel (and thus the astronaut) as they change direction. This force does not directly cancel out the original recoil. Instead, it adds a new set of forces that are complex due to the curved path of the bullets.
Direction and Magnitude of Forces:

The force exerted by the redirected bullets is not directly opposite to the recoil force. Instead, it's more inward, following the curvature of the barrel.
Also, energy is lost in the process of redirecting the bullets. This loss occurs due to friction, heat, deformation of the barrel, etc. So, the force exerted by the returning bullets will be less than the original recoil force.
Conservation of Angular Momentum:

If the astronaut were spinning, the conservation of angular momentum would come into play, as mentioned earlier. However, this principle doesn't directly affect the linear motion (forward or backward movement) caused by the recoil and redirected bullets. It would only affect how fast the astronaut spins if he were rotating.
Net Movement:

The net movement of the astronaut depends on the sum of all forces and motions. In your scenario, the initial recoil sets the astronaut moving backward. The redirected bullets add another layer of motion but don't completely negate the initial movement. The astronaut ends up moving backward, but possibly at a different speed than the initial recoil velocity, depending on how much momentum is transferred back by the bullets.
No External Force to Stop:

To stop completely, an external force equal in magnitude but opposite in direction to the astronaut's current momentum would be needed. The scenario with the curved barrels does not provide such a force; instead, it introduces additional forces that modify but do not entirely counteract the astronaut's initial momentum.
In summary, the astronaut doesn't stop in place because the forces exerted by the redirected bullets don't directly cancel out the initial recoil force. Instead, these forces interact in a more complex way, changing the astronaut's speed but not necessarily bringing him to a complete stop.