>Not sure if this is a joke, but I'll bite.

Everything in the Universe (paradoxically I might add!) -- is both deadly serious -- and a highly humorous joke!

It is also neither!

What anything is (terrible, funny, neither) -- depends on the perceiver's understandings in the matter...

Simple example: A long time ago, The Common Cold was not well understood -- and people often died from it (the term is called "The Chills" in Victorian Literature).

The Common Cold -- back then -- was a highly serious matter!

You didn't joke about it, you didn't make fun about it -- it was not socially apropos to do so!

But these days, well, you can make all of The Common Cold jokes you want -- nobody will bat an eye... but they probably won't be all that funny (that is, they'll fall into the 'neither' category!).

The time that Common Cold jokes would have been the funniest -- would have been at the time where cures for The Common Cold were being discovered -- and half of the population knew about them, but half didn't!

You see, then a bunch of renegate doctors (who were in the know! ("Take more Vitamin C" -- or whatever!) -- could have made fun of it with a bunch of other renegade doctors (who were also in the know!) -- and the joke would have been actually funny! To them, with their understandings, at that time!)

But, it's more neutral these days... since everyone knows, and no one cares...

But all humor or seriousness (or neither!) -- is relative to the proverbial "eye of the beholder"...

>Those are called ionocrafts. They work by ionizing air particles. They're basically low-tech ion drives. They don't work in vacuum.

This is an excellent response -- because this response raises several questions that prior to it, I didn't think of asking! They are:

1) Are we really sure that electric-only (no gas, Krypton, Xenon, or otherwise) propulsion doesn't work in the vaccuum? Sure, we could take an arbitrary scientist's word for this -- but I'd much rather somehow get to space -- to test it for myself.

OK, so now, let's suppose that that doesn't work...

If it doesn't -- then we now need to analyze the difference between a gas-based (Krypton, Xenon, etc.) ion thruster that does work -- and a purely electric one that we speculate does not.

Now, I'll do a quick version of that in my mind...

See, the difference is that we're accelerating actual particles of matter, gas to be precise, (Xenon, Krypton, etc.) -- at very high speeds out of a nozzle; the electricity is used for generating radio-frequency waves in a cavity (similar to a microwave oven) -- which in turn excites and accelerates the gas (which in turn is directed by the cavity and/or magnets and/or electromagnetic fields in that cavity...)

That's one of the directions of the movement -- but we're interested in the opposite direction -- the direction of the thrust.

So what does that get down to?

Well, the Xenon, Krypton -- are not at pressure; that is, unlike a conventional rocket engine -- there is no pressure from the expansion of the gas in a chamber!

So what else might be going on?

OK, here's the thing:

As far as I can tell, at this point in time -- everything in a gas-based ion drive that DOES work in outer space -- is based on INERTIA.

Basically, somehow (and science needs to study this more!) -- there's an INERTIAL LOCK between the Krypton or Xenon particles -- and some/all other parts of a functioning gas-based ion drive!

Think of it this way, you're climbing up a rope, the rope goes down (relative to your position), you go up, (relative to the rope).

Your hands have an INERTIAL LOCK -- on the Rope!

Well, same thing in the working ion thruster -- but all or part of that machinery -- somehow has an INERTIAL LOCK (magnetic, RF, or otherwise!) -- on the Krypton or Xenon particles!

That's important -- because see, if you understand that, the next step is the following question:

2) What else can we gain an INERTIAL LOCK on? Can we gain an INERTIAL LOCK on smaller gas particles? What about water (I believe this is already proven in submaries that use electricity to move water).

But but... the real grand-master Physics question (after answering all of those becomes something like):

3) Can we gain an INERTIAL LOCK -- ON SPACE ITSELF?

?

Now, at this point in time -- I don't know the answer to that!

But, a great response -- as I wouldn't have considered thinking of these questions, or writing this, without it!