I have a way of giving something negative mass. Did I just end the world,or usher in a golden age of space travel?

Question

So, somehow, I have discovered a process that makes an objects mass negative. Not its weight, its mass (although, I guess that the weight would also become negative). The thing is, before I try it, I want to know if this is a bad idea.

A number of scary words spring to mind, such as "strange matter", "white holes", and maybe even "naked singularity". However, I am not really the sort of guy who can do special relativity, so I have no idea which of these might happen. They never taught that at school.

Why might it be a good idea? Well, everyone loves themselves a good space opera. To get a space opera, you need FTL. A number of theoretically possible FTL drives need some parts to have negative mass to work. Another thing that could use this might be airships or planes. Just stick a lump of processed material in it, and you don't need to worry about going down because of engine failure in the case of planes. Or, in the case of airships, you don't need to have such a large balloon, which makes potential tourists nervous. You can even make floating islands in the sky! (tie them down though, unless you want them floating away into space). Oh yes! you can also use this method to get to space and back for almost free! Just collect enough mass while you're up there, and you can come back down again. If you feel like you are going down too fast, you can always use a parachute.

So, yeah. a lot of reasons that it might be useful.

But, this matter is going to be quite strange. Does it qualify as strange matter? If so, will it cause a chain reaction, like shown in a certain Kurzgesagt video?

Basically, what I'm asking is the following:

If a process* can multiply the mass of any** object by negative 1, does special relativity or quantum mechanics, or basically any other sub-field of physics cause this process to have drastic consequences?

*: the process, while the setup takes a long time, works through about one cubic meter of any material per millisecond. (you can change the rate for your answer)

**: This is something artificial, and I am no supervillain. I won't do it to anything bigger than, say, a brick.

Assumptions:

• negative mass gets repulsed by gravity. I guess that means that it should also be repulsed by any acceleration?
• The mass-reversal either works completely, or not at all.
• this actually happens.

Answer 1

Even before getting to the consequences of easily created negative mass, remember that FTL by itself, even without considering how it is implemented, implies time travel. Note that it does not require time travel, and the existence of privileged reference frames or some form of chronology protection mechanism would prevent everything just disintegrating into a sea of paradoxes.

With that aside, even with privileged frames (or whatever) negative mass that has the the "runaway motion" that you want is hideously dangerous and breaks all sorts of bits of physics.

Even if you limit it to something brick-sized, you can end up with something that takes a pair of brick-equivalents and accelerates them to arbitrarily high relativistic speeds with no input of energy. Such a device, especially if multiple such devices were used, is the sort of thing that can be used to smash planets. It puts relativistic kill vehicles in the hands of anyone capable of building one of your levitation, reactionless drive or FTL devices. No input of energy is required, so there's no launch signature. They'll be undetectable, unstoppable, and incredibly destructive.

Any projectile that misses its target will presumably keep getting faster until it is either vapourised by the blue-shifting of the cosmic microwave background, or it turns into a miniature black hole and promptly and violently evaporates.

Further more, you've also created a perpetual motion machine of the first kind (just put some of your negative mass on the rim of a wheel) so everyone has as much free energy as they could ever want or need, and then some. You can create tanks of gas which will spotaneously heat up, turning into instant free-energy bombs.

I'm sure there's more I haven't thought of.

It might be worth considering that negative mass isn't the only thing you can make FTL with... there are more subtle distinctions, like negative energy and negative pressure that might help you build warp drives and wormholes. Reactionless warp drives are also hideously dangerous (because anyone can use them to make relativistic kill vehicles) but at least they don't break thermodynamics at the same time as destroying everywhere intelligence has ever lived.