3 ms·

Yeah I've never looked at collisions. But if you blindly plug a negative mass into newtonian gravity F=GM1M2/r2. And then use F=ma or a=F/m you get a=GM/r2 wh

Yeah I've never looked at collisions. But if you blindly plug a negative mass into newtonian gravity F=GM1M2/r*2. And then use F=ma or a=F/m you get a=GM/r*2 where M is the other mass, and a is our acceleration toward that mass. Positive masses attract everything where negative masses repel everything. One of each held at constant separation should accelerate together. This is why I want to know if antimatter falls up. Or I guess it might fall down but repel regular matter in which case it'll be very hard to detect.

Dylan16807 4y ago
Antimatter just has the opposite electrical charge. It doesn't do anything weird at all with gravity.
- sycren 4y ago
  Since it focuses on electrical charge, would it be worth renaming it to Anti-charged-matter Are there other types of Antimatter that focus on different properties?
  - mayoff 4y ago
    Antimatter also has anti-color-charge. Quarks have a ‘color charge’ (unrelated to visible colors) which is ‘red’, ‘green’, or ‘blue’. An antiquark is antired, antigreen, or antiblue (and has the opposite electrical charge from its corresponding normal quark). https://en.wikipedia.org/wiki/Color_charge https://en.wikipedia.org/wiki/Color_charge
    - phkahler 4y ago
      Could anti-quarks behavior be explained by them having negative mass instead?
      - monocasa 4y ago
        I don't believe so; color charge isn't a scalar like mass is.
      - KMag 4y ago
        That would require a re-formulation of conservation of color charge. You could probably come up with an alternative formulation where everything is consistent, but all of the formulas would almost certainly be more complicated. The most obvious way would end up replacing color by the sign of mass times color everywhere, but then you've just renamed ant-red, anti-blue, and anti-green, with no obvious benefit.
- phkahler 4y ago
  >> Antimatter just has the opposite electrical charge. We don't know that. It may have the regular charge but after computing the force it may experience the opposite behavior via F=ma since the mass is negative. We don't really know if the charge is opposite or the mass. Blindly using the equations you may get similar results depending where you stick the negative. Also, I seem to recall Dirac predicting the existence of antimatter because some solution to an equation had an m^2 term and when you take a square root to solve for m there are two solutions. Then the positron came along and this was forgotten and people just assumed it had positive charge rather than negative mass.
  - thfuran 4y ago
    Antimatter isn't some unobserved theoretical thing. It's produced daily at most large hospitals. We absolutely know that its electric charge is opposite that of the normal matter counterpart.
    - phkahler 4y ago
      How do we know that? Because of how it behaves in electric and magnetic fields. In particular, how it accelerates. It obviously has a negative sign in it somewhere. My point is that we don't know if that sign flip is in charge or mass. A lot of the math behaves in accordance with observation whether we flip the charge or the mass.
      - thfuran 4y ago
        >How do we know that Both theory and experimental validation. Their interaction with electric fields, their interaction with gravity, conservation laws, and so on.
      - tiborsaas 4y ago
        Recent experiment at CERN: https://www.space.com/matter-antimatter-same-response-to-gravity https://www.space.com/matter-antimatter-same-response-to-gra...
    - fooker 4y ago
- monocasa 4y ago
  IIRC, we don't actually know that for sure yet. I've seen some proposals for for experiments that use the relative stability and neutral charge of the exotic atoms muonium and anti-muonium to validate that anti muons don't have negative mass as well as flipped charge.
p1mrx 4y ago
"the BASE collaboration has shown, within strict boundaries, that antimatter does in fact respond to gravity in the same way as matter" https://www.riken.jp/en/news_pubs/research_news/pr/2022/20220106_1/index.html https://www.riken.jp/en/news_pubs/research_news/pr/2022/2022...
- lambdasquirrel 4y ago
  That’s negative charge though, not negative mass. We haven’t been able to experiment with negative mass. No particle physics experiment has produced any evidence it exists.
- phkahler 4y ago
  No, that doesn't cover the correct situation WRT gravity.

Yeah I've never looked at collisions. But if you blindly plug a negative mass into newtonian gravity F=GM1M2/r*2. And then use F=ma or a=F/m you get a=GM/r*2 wh

Dylan16807 4y ago

Antimatter just has the opposite electrical charge. It doesn't do anything weird at all with gravity.

sycren 4y ago
Since it focuses on electrical charge, would it be worth renaming it to Anti-charged-matter Are there other types of Antimatter that focus on different properties?
- mayoff 4y ago
  Antimatter also has anti-color-charge. Quarks have a ‘color charge’ (unrelated to visible colors) which is ‘red’, ‘green’, or ‘blue’. An antiquark is antired, antigreen, or antiblue (and has the opposite electrical charge from its corresponding normal quark). https://en.wikipedia.org/wiki/Color_charge https://en.wikipedia.org/wiki/Color_charge
  - phkahler 4y ago
    Could anti-quarks behavior be explained by them having negative mass instead?
    - monocasa 4y ago
      I don't believe so; color charge isn't a scalar like mass is.
    - KMag 4y ago
      That would require a re-formulation of conservation of color charge. You could probably come up with an alternative formulation where everything is consistent, but all of the formulas would almost certainly be more complicated. The most obvious way would end up replacing color by the sign of mass times color everywhere, but then you've just renamed ant-red, anti-blue, and anti-green, with no obvious benefit.
phkahler 4y ago
>> Antimatter just has the opposite electrical charge. We don't know that. It may have the regular charge but after computing the force it may experience the opposite behavior via F=ma since the mass is negative. We don't really know if the charge is opposite or the mass. Blindly using the equations you may get similar results depending where you stick the negative. Also, I seem to recall Dirac predicting the existence of antimatter because some solution to an equation had an m^2 term and when you take a square root to solve for m there are two solutions. Then the positron came along and this was forgotten and people just assumed it had positive charge rather than negative mass.
- thfuran 4y ago
  Antimatter isn't some unobserved theoretical thing. It's produced daily at most large hospitals. We absolutely know that its electric charge is opposite that of the normal matter counterpart.
  - phkahler 4y ago
    How do we know that? Because of how it behaves in electric and magnetic fields. In particular, how it accelerates. It obviously has a negative sign in it somewhere. My point is that we don't know if that sign flip is in charge or mass. A lot of the math behaves in accordance with observation whether we flip the charge or the mass.
    - thfuran 4y ago
      >How do we know that Both theory and experimental validation. Their interaction with electric fields, their interaction with gravity, conservation laws, and so on.
    - tiborsaas 4y ago
      Recent experiment at CERN: https://www.space.com/matter-antimatter-same-response-to-gravity https://www.space.com/matter-antimatter-same-response-to-gra...
  - fooker 4y ago
monocasa 4y ago
IIRC, we don't actually know that for sure yet. I've seen some proposals for for experiments that use the relative stability and neutral charge of the exotic atoms muonium and anti-muonium to validate that anti muons don't have negative mass as well as flipped charge.

p1mrx 4y ago

"the BASE collaboration has shown, within strict boundaries, that antimatter does in fact respond to gravity in the same way as matter" https://www.riken.jp/en/news_pubs/research_news/pr/2022/20220106_1/index.html https://www.riken.jp/en/news_pubs/research_news/pr/2022/2022...

lambdasquirrel 4y ago
That’s negative charge though, not negative mass. We haven’t been able to experiment with negative mass. No particle physics experiment has produced any evidence it exists.
phkahler 4y ago
No, that doesn't cover the correct situation WRT gravity.