Transparent Conductors would be useful for solar panels, touch screens, and flat panel displays.
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Iām pretty sure antimatter has positive mass.
If it had negative mass, then all attractive forces would repel it, and vice-versa because F=MA. In that situation, gravitational interactions between positive and negative mass would create a repulsive force, because Fg=GMM/R^2 would yield a negative value, and the positive mass would accelerate away from the negative and the negative mass towards the positive.
Apart from the weak force, matter and antimatter are supposed to be CPT symmetric, and as we can see, positive mass and negative mass particles arenāt CPT symmetric.
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So not that great. If weāre imagining uses for things that violate the laws of physics, you can get a lot better than that. 
This is a serious question. I think it is mostly expected to work the same as regular matter, with a positive āgravitational chargeā equal to its inertial mass. But we are still working on a full theory of quantum gravity and itās not impossible to make ones where it has the opposite value. So to be perfectly sure you would need an experiment, and because gravity is so minimal on the scale of atoms, I think nobody has managed to do it yet.
Invoking CPT symmetry seems a little bit cheating to me ā the C is charge of all types, currently electromagnetic, weak, and color. If it did turn out gravitation works the same way, then mass would simply be another part of that too.
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Except that such things exist-- and synthesis of newer, cheaper, and better compounds is driven by these prosaic applications.
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Huh. Fair enough, I guess you can compromise between the two closer than I thought. Thank you.
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You would get the same CPT symmetry violations with an electric charge and negative mass, relative to comparable particles with positive mass. For example, 2 positively-charged negative-mass objects would tend to accelerate towards each other, because repulsion would work backwards. And running that in reverse, theyād still accelerate towards each other.
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Very much so. I took the question as whether antimatter would fall up in say the Earthās gravitational field, not whether it would attract other antimatter. The second has to be the case, the first could depend.
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Iām working on the assumption that:
Fg = GMM/R^2
So if both masses are positive or both are negative, you ge inward force, and if one is positive and the other is negative you get outward force, and
F = MA
So if mass is positive, an inward force leads to an inward acceleration and an outward force leads to outward acceleration, but if mass is negative, it is reversed.
That causes the possibility that a positive and negative mass could accelerate each other in the same direction. While conserving momentum and energy if the masses cancel out.
I am so not a physicist but the Newtonian-level math seems clear enough.
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Invisible trains! Transparent conductors would be very useful for that. (Please forgive the levity.)
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(It took me far too long to find this PBS Space Time episode, considering that the problem immediately reminded me of this one
)
(From the challenge question at the end: āLetās say the two objects are about the size of apples, but to get some decent power output, make them the density of a neutron starā¦ā )
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The Newtonian level math seems clear enough, but it makes the assumption that inertial mass in F = MA and gravitational mass in Fg = GMM/R2 are the same. Which they probably are, you know, thatās sort of the whole premise of general relativity. But outside that theory they donāt have to be.
You could for instance imagine a case where gravitational mass can be equal to either +M or -M. Then it would work a little like electromagnetism in reverse: like gravitational masses attract, unlike gravitational masses repel. And that much is no more paradoxical than it is for electrons and positrons to have opposite electromagnetic charge.
Antimatter was first predicted when it was discovered that relativistic quantum mechanics doesnāt let you exclude negative energy states. Dirac fixed that by supposing all such states were already occupied in a vaccum; in which case you can get holes. They work just like particles, with the same rest energy E0 = Mc2, but will respond to and create forces in the opposite direction.
And, well, thatās not actually how quantum field theory turns out to work. But it does show you how one could expect an antiparticle to fall up instead of down. And like I said, I donāt think itās been firmly ruled out as a possibility yet.
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Theyāre naming it the Veloci-chomper.
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Like an ostrich? or like Effigia? How about ornithomimimimimimus? But, alas, no evidence of a beak.
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Warning: related to current events, specifically George Floyd
Youtubeās added this creator to my recommended list a few times, but I generally donāt watch (although the few Iāve watched have been interesting, the presentation usually doesnāt quite fit with me). Howeverā¦ this is a pretty comprehensive, and non-hyperbolic, analysis of the George Floyd toxicology report. I canāt vouch for the science (hence, this topic), but it is referenced and seems to cover a lot of the possibilities.
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I donāt know about the book, but the website is outstanding.
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Doesnāt exactly count as ānewsā, butā¦
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