BUT http://en.wikipedia.org/wiki/Negative_mass#cite_note-1 I tried to google for Robert L. Forward's paper to no avail, thus I'm forced to derive all the stuff he proposed (shown in that wikipedia article) Therefore I'd like to ask what have I done wrong that causes the na[sub]1[/sub]t failed to cancel out? P.S. For those wondering what I am doing, the above maths is a portion of my scifi wiki. In this wiki, negative mass is one of the 12 types of matter I needed for my scifi. The above step is tried to show that the masses obey the conservation of momentum but to no avail P.S.2 Because negative mass is still highly speculative, and this post is scifi oriented, it does not belong to the physics subforum

If I use \( \frac{a_1}{a_2}=\frac{1}{n}\) instead of \(\color{Lavender} \frac{a_1}{a_2}=-\frac{1}{n}\) Then the na[sub]1[/sub]t can be cancelled out But isn't by the newton's law of gravitation we get \(\color{Lavender} \frac{a_1}{a_2}=-\frac{1}{n}\) I know in one dimensional cases, the - sign determines an opposite direction I also know from both drawing free body diagrams and the information provided in wikipedia, that both acceleration vectors point to the same direction But what does the - represent if both a1 and a2 point to the same direction?

Though you are seeking assistance for a SciFi project, as long as you make it clear that you are seeking assistance with the math, you might have better response in the Science and Math folder. There are many instances where "scientists" including mathematicians, advise on the science and math for both fiction and science fiction, books and movies. Just make your intent and request clear and you should be ok. iOW don't post in a way that the SciFi aspect is dominant or could be confused with a statement of science.

@1st sentense I'll take you suggestion if I have more maths problems needed in my scifi For this particular case in this thread it is difficult as the problem is not just the maths. What I struggle here in this particular case is the interpretation of the - sign,m which leads to incorrect maths result (I have multiple checked my maths thus no careless mistakes should be responsible). Because an interpretation is involved, it means this question has a physical aspect in it. Therefore if a user ask me what is this all about, then I will have to spill out the word "negative mass" (a highly speculative subject) I will be then said as cranky/scifi and receive no response or worse @2nd sentense LOL, I didn't expected that, I thought the authors made up all the equations by themselves @3rd sentense Umm mind give me an example on how should I post it?