On Wed, Apr 19, 2017 at 04:41:28PM -0700, C. Berry wrote:
> To be consistent, negative mass would have to have negative kinetic energy
> when in motion relative to you. And yes, it's impossible for me (and I'd
> think for anyone) to picture what would happen physically if you tried to
> use your hand to push a ball of negative matter.

The usual way these sorts of thought experiments end is "you die and
so does everyone around you".

This one looks to be no different, though with variations that would
depend upon possible details of its properties.  Nearly every case
I've looked at so far ends with the negative matter expanding at near
the speed of light, a good deal of ordinary matter also expanding very
fast, and enormous amounts of radiation.  Only the intermediate causes
vary.

The only case I could come up with that doesn't end in such disaster
is where the negative mass matter does not interact in any significant
way with either massless radiation or ordinary positive-mass matter.
In which case the answer to "what happens when you touch it" is simply
"nothing whatsoever, you can't even detect that it's there".

- Tim