3 ms·

one of the most interesting of antimatter experiments is that if they somehow showed antimatter only experience 60% gravity, that will be huge. (earlier result

by ycui1986 1y ago

one of the most interesting of antimatter experiments is that if they somehow showed antimatter only experience 60% gravity, that will be huge. (earlier result of measuring antimatter’s gravity showed they don’t posses antigravity, but they seems to experiences less gravity. I guess a dedicated follow up experiment will likely get better measurement on whether antimatter indeed experience less gravity.)

whatnow37373 1y ago
I believe this was already settled? Didn’t it just experience gravity the same way?
- kazinator 1y ago
  Antimater has positively charged electrons (positrons) and negatively charged protons (antiprotons). Its neutrons are antineutrons made of a positron and antiproton. So just the charges are swapped around. Charges interact with electric fields. Gravity is related to mass. It doesn't matter whether the bulk of the mass comes from negatively or positively charged particles. Of course, antimatter has opposite electrical attraction. If an antimatter plastic comb attracts antimatter styrofoam crumbs, those crumbs will be repelled by the matter plastic comb (luckily for them).
  - prox 1y ago
    So…wait , can anti-mass particles exist? Like an inverse Higgs boson?
    - kazinator 1y ago
      https://en.wikipedia.org/wiki/Negative_mass https://en.wikipedia.org/wiki/Negative_mass
  - gus_massa 1y ago
    > Its neutrons are antineutrons made of a positron and antiproton. Neutrons are made of on up quarks and two down quark (and a lot of gluons). Antineutrons are made of on up antiquarks and two down antiquark (and a lot of gluons). There are no (anti)protons or (anti)electrons inside (anti)neutrons. > Of course, antimatter has opposite electrical attraction. Nitpicking: attraction -> charge > If an antimatter plastic comb attracts antimatter styrofoam crumbs, those crumbs will be repelled by the matter plastic comb (luckily for them). IIRC the charge in the comb induces a charge in the crumbs. If the charge of the comb is X, the -X charges move closer to the comb, and the X charges move far away. And that those displaced charges create a dipole that is attracted to the comb. So I think the anti-comb would attract the normal-crumbs and create a huge explossion.
zombot 1y ago
It would be top sci-fi if anti-matter had anti-gravity.
fsh 1y ago
This is incorrect. The only measurement of antimatter gravity so far by ALPHA-g resulted in no difference to normal matter within the experimental uncertainty [1]. This is not surprising, since any difference would violate conservation of energy. [1] https://www.nature.com/articles/s41586-023-06527-1 https://www.nature.com/articles/s41586-023-06527-1

whatnow37373 1y ago

I believe this was already settled? Didn’t it just experience gravity the same way?

kazinator 1y ago
Antimater has positively charged electrons (positrons) and negatively charged protons (antiprotons). Its neutrons are antineutrons made of a positron and antiproton. So just the charges are swapped around. Charges interact with electric fields. Gravity is related to mass. It doesn't matter whether the bulk of the mass comes from negatively or positively charged particles. Of course, antimatter has opposite electrical attraction. If an antimatter plastic comb attracts antimatter styrofoam crumbs, those crumbs will be repelled by the matter plastic comb (luckily for them).
- prox 1y ago
  So…wait , can anti-mass particles exist? Like an inverse Higgs boson?
  - kazinator 1y ago
    https://en.wikipedia.org/wiki/Negative_mass https://en.wikipedia.org/wiki/Negative_mass
- gus_massa 1y ago
  > Its neutrons are antineutrons made of a positron and antiproton. Neutrons are made of on up quarks and two down quark (and a lot of gluons). Antineutrons are made of on up antiquarks and two down antiquark (and a lot of gluons). There are no (anti)protons or (anti)electrons inside (anti)neutrons. > Of course, antimatter has opposite electrical attraction. Nitpicking: attraction -> charge > If an antimatter plastic comb attracts antimatter styrofoam crumbs, those crumbs will be repelled by the matter plastic comb (luckily for them). IIRC the charge in the comb induces a charge in the crumbs. If the charge of the comb is X, the -X charges move closer to the comb, and the X charges move far away. And that those displaced charges create a dipole that is attracted to the comb. So I think the anti-comb would attract the normal-crumbs and create a huge explossion.

zombot 1y ago

It would be top sci-fi if anti-matter had anti-gravity.

fsh 1y ago

This is incorrect. The only measurement of antimatter gravity so far by ALPHA-g resulted in no difference to normal matter within the experimental uncertainty [1]. This is not surprising, since any difference would violate conservation of energy. [1] https://www.nature.com/articles/s41586-023-06527-1 https://www.nature.com/articles/s41586-023-06527-1