From Baldeee Post 13 Can you provide a link to Web Site where the alleged article was Posted? What I have read about Bose-Einstein condensates included no mention of strange mass/momentum properties. I am certain that if a force on atoms in a condensate would not cause the atoms to accelerate in the opposite direction of the applied force. The weirdness of such a condensate is that the atoms are almost motionless near absolute zero & each atom seems to occupy much more than the usual volume. The volumes of space occupied by each atom can overlap, making it difficult (impossible?) to identify individual atoms. The above is strong evidence supporting the Heisenberg Uncertainty Principle. I do not believe there is negative mass. Antimatter has the same mass properties as normal matter & there is no type of mass other than normal & antimatter mass.
I can do better - I can point you not just to the website (and I did mention BBC) but to the offending article itself. Please Register or Log in to view the hidden image! http://www.bbc.co.uk/news/science-environment-39642992 Managed to find it again at last. Not what the article suggests they observed. Now, as mentioned with Michael, whether this is true "negative mass" or just a localised appearance of properties that we might expect negative mass to say, I could not say.
Trying to make sense of this. It reminds me a little of spacetime diagrams showing light cones. But the part about negative mass doesn't fit that picture. I'm probably reading in stuff that isn't there. ethernos's posts are like a Rorschach test.
No, I got the same image. I think you're spot-on. In a paint program such as Photoshop, when you scale an object and shrink it below 0 pixels, it simply flips upside down and grows again (because you're controlling one of the corners, and essentially giving it negative coordinates). Ethernos is seeing the double cone this way. And, presumably, thinking of the collapse of mater as the centre of a black hole.
Correction: I did not mean to liken my mater to a massive black hole. In fact, she is a kind, sweet, tiny woman of no more than 90 pounds.