On Wed, Apr 19, 2017 at 6:38 PM, C. Berry <xxxxxx@gmail.com> wrote:
> To do that, you have to slow the exhaust down to match the speed of your
> ship, which, with the exaust being negative matter, slows your ship down
> again, too.
>

I'm having one of those twisted thought experiment moments...

So I have a  -1kg ball of negative mass matter.
While floating in the vacuum of space, I throw it away from me
("Sunward") at 1g for 1 second. Not sure how I throw for a whole
second, I guess I have a jai lai stick thing or something.
This should impart an accel of 1 newton on my hand away from the
direction of the toss
I mass around 100kg (sigh), so I start moving at 0.01 m/s  backwards.
("Rimward")

Equal and opposite reaction means the ball gets 1m/s, but it's
negative mass, so it gets -1m/s in the direction opposite to me.
Which is to say it's moving -1m/s Sunward, or 1m/s Rimward
So, mere milliseconds after leaving my hand, it catches up and lands
in my hand again.

All well and good, and here I think I have an M-Drive.

The part I'm unsure/confused about is.... when the ball hits my
catcher's mitt, there should be energy transfer again, right?
So, does the impact speed me up, or is it a negative impact and it
slows me down?

Or, since there should me minimal energy loss, does the ball not
really "throw", but just push back against me ?

In the article, "It looks like the rubidium hits an invisible wall."

I'm imagining a closed chamber, with a jet nozzle on the front end,
and a scoop on the back.
Along the sides of the box is something like the lasers used in the
article to negate the mass of the rubidium in the article.
You squirt "propellant" in to the box, then negate it's mass. It "hits
the wall" and stops.
The recoil from the squirt nudges the box forward, bringing the scoop
at the back to where the non-moving cloud is.
The scoop recovers the stuff, and at a much slower pump rate moves it
back to the front of the box.

Major violation of conservation of momentum.... unless the negative
"in the box" balances the positive of being pumped back to the front
of the box.

> On Wed, Apr 19, 2017 at 3:33 PM, Jeffrey Schwartz
> <xxxxxx@gmail.com> wrote:
>>
>> On Wed, Apr 19, 2017 at 11:34 AM, David Shaw <xxxxxx@gmail.com> wrote:
>> > The Alcubierre drive is a theoretical FTL drive which, unlike so many
>> > others, does not violate relativity. Unfortunately, it requires negative
>> > mass to work.
>> >
>> > Well, if http://www.bbc.co.uk/news/science-environment-39642992 is to be
>> > believed, we may very well have just discovered how to create negative
>> > mass.
>> >
>> > Interesting...
>> >
>>
>> "With negative mass, if you push something, it accelerates toward you,"
>>
>> Potentially M-Drives too.
>> Would a rocket motor with negative mass exhaust be able to recover the
>> propellant?
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