AH HAAA !!!!

When it's all over, the pipe has moved a short distance then stopped.

EXACTLY , thats how it works.

reactionless propulsion , I rest.

the (distance you can travel) depends on the lenght of the ladder and the force you can supply.

the (distance you can travel) depends on the the size of the pipe and the pressure in the tank.

we only used 100 psi , but what if the pressure was
higher , and what if we were using liquid air.

liquid air density 870 kg/m^3

I know it would be alot more technical than just using
compressed air in a non liquid state , but you could go
for quite a trip with 1000 cu ft of liquid air.

3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.