What would happen if you had a ball of antimatter?

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    Antimatter Ball
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Discussion Overview

The discussion revolves around the hypothetical scenario of a ball of antimatter interacting with a ball of matter, exploring the nature of their annihilation reactions in both vacuum and atmospheric conditions. Participants examine the speed, size, and energy dynamics involved in such interactions, as well as the resulting phenomena.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that in a vacuum, if a ball of antimatter and a ball of matter are thrown at each other, they might blow apart and remain largely unreacted depending on their speed and size.
  • Others argue that the annihilation reaction would occur very quickly, resulting in an explosion that produces photons equivalent to the energy of the masses involved.
  • It is suggested that in atmospheric conditions, the antimatter ball would rapidly evaporate due to initial surface annihilations, leading to a violent reaction similar to a nuclear explosion.
  • One participant notes that the energy from nucleon/antinucleon annihilations primarily produces pions, with subsequent decays leading to high-energy photons and other particles.
  • Another participant highlights that over 99.95% of the energy is contained in the nucleons, with the electron/positron contributions being minimal.
  • Concerns are raised about the time frame for the reaction, with estimates suggesting that initial reactions would occur in microseconds, leading to a fireball of hot plasma that continues until all antimatter is consumed.

Areas of Agreement / Disagreement

Participants express differing views on the specifics of the annihilation process, including the dynamics of the reaction in vacuum versus atmosphere, the role of nucleons, and the time scale of the reactions. No consensus is reached on these points.

Contextual Notes

Limitations include assumptions about the size and speed of the balls of matter and antimatter, as well as the dependence on environmental conditions. The discussion does not resolve the complexities of the annihilation process or the exact nature of the energy distribution.

Physt
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If you had a ball of matter and anti-matter in a vacuum and threw them at each other - would they just blow apart and go largely unreacted?

What about in atmosphere - would the ball of anti-matter blow up or form a shell of exploding material around it insulating it like the boiling of liquid nitrogen on your hand keeps it from freezing you? How long would such a reaction take to complete for a baseball of anti-matter at 1 atmosphere?
 
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If you hit a ball of antimatter with a ball of matter, then they will "explode"= they will give photons of the same energy as the two balls' masses...

What do you mean blow up or form a shell of exploding matterial? The "reaction" (annihilation) will happen really fast (in macroscopic world) if the matter meets its antimatter...
 
Physt said:
If you had a ball of matter and anti-matter in a vacuum and threw them at each other - would they just blow apart and go largely unreacted?
That depends on the speed and size. If you do it slow enough, initial annihilation reactions will quickly push both balls away from each other. If they survive without getting blown apart from the released energy, they might escape without a large reaction. The same can happen with fission weapons, by the way, if they reach criticality too slowly.

In the atmosphere, the ball of antimatter would quickly evaporate from initial annihilations on its surface. With a reasonable size (e.g. similar to a nuclear bomb, a baseball-sized ball fits here), most of the annihilation energy escapes the annihilation region and your reaction gets very violent until all the antimatter annihilated.

ChrisVer said:
If you hit a ball of antimatter with a ball of matter, then they will "explode"= they will give photons of the same energy as the two balls' masses...
Muons and neutrinos (from charged pion decays) get a significant fraction of the energy in baryon annihilations.
 
pion decays?
 
What is the question?
Nucleon/antinucleon annihilations mainly produce pions (strong interaction >> electromagnetic interaction). Neutral pions decay to two high-energetic photons, charged pions mainly decay to a muon and a neutrino.
 
oh ok then,,, I didn't think of Nucleons
 
Over 99.95% of the energy is in the nucleons. The electron/positron contribution is very small.
 
Physt said:
How long would such a reaction take to complete for a baseball of anti-matter at 1 atmosphere?

Initial reaction on the surface would quickly (microseconds or even less) turn the ball and surrounding air into an expanding fireball of hot plasma, quite similar to a nuclear bomb detonation. The annihilation inside the fireball will continue until all antimatter is consumed, within some milliseconds.
 

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