Those were the points I was trying to make, Gourdhead. If you are going to accelerate at a constant 1g, then you have to constantly be expelling propellant to do so. If a flight is going to take even days for an interplanetary trip the amount of propellant has to be large to maintain that thrust, which is why I questioned the ability for this system to even place itself into Earth orbit before launching on its trip to Mars or Wolf359 (total vehicle weight vs thrust). Or will this have to be assembled piece by piece in orbit?

And even encountering a diffuse gas at near lightspeed would destroy the craft without some form of protection, which at the moment doesn't exist. You could use magnetic fields to protect against ions, but that doesn't stop molecules. Just hoping not to hit anything is not a wise way to fly.

And, starship1, I'm an accountant, but I try to keep up with physics and general scientific advancements. I'm was previously aware of the old Nerva system and the new Project Promethius, as well as most of the theoretical systems detailed on the JPL website you so often refer to. I don't appreciate being insulted because I question the feasibility of your system.

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...and we'll be saying a big hello to all intelligent life forms everywhere; and to everyone else out there, the secret is to bang the rocks together, guys...