Is It Possible To Have Entire Planets Composed of Antimatter

[SamuraiBlue]

Re: Is It Possible To Have Entire Planets Composed of Antima

Christopher said:
On second thought, though, I'm skeptical about the edge repulsion. That novel was correct about the basics -- if an unconfined M/AM reaction begins, the energy of the initial annihilation would heat the gases enough to blow them apart and halt the reaction before it progresses. But there we're talking about concentrations dense enough for a fair number of annihilations to occur in the first place. Here, we're talking about interstellar gas and dust, where you might have one particle per cubic centimeter. The odds of any one particle hitting an antiparticle would be so low that the particles and antiparticles could intermingle significantly with very little interaction/annihilation. In fact, we know for certain that this happens, because as I said above, there are already plenty of antiparticles up in orbit of Earth, Saturn, and other worlds, held there by their magnetic fields. There are plenty of particles there too, but annihilations are rare because the particles are so tiny and the spaces between them so comparatively huge.

So if you started out with a proto-galaxy containing a mix of matter and antimatter, I think they'd pretty much intermingle rather than being in separate clumps with clear repulsive boundaries between them. If a region of mixed matter/antimatter gas then began to condense -- the first step of forming a star system -- then as it got denser, annihilations would become more frequent, and the proto-system would get blown apart before it could form.

I really don’t think anyone can answer this question with certainty without simulating it with a super computer since if certain large amount of AM was caught during formation of a proto-galaxy then gravity will also plays a part in the confinement process.
Do you know the game of Go where you try to dominate space by constantly trying to contain the opponent by enveloping their move?
If AM and M were to be caught within a gigantic gravity well then I think it will start playing a game of Go and the borders will be void of space while matter and anti-matter will start clumping up together into groups. When a group of same polarity meets they merge when an opposite polarity meets they either cancel each other out or become more condensed due to edge repulsion. Through this process an interstellar cloud could collapse to form a planetary system.
Intriguing idea I would say.

 

[Christopher]

Re: Is It Possible To Have Entire Planets Composed of Antima

SamuraiBlue said:
If AM and M were to be caught within a gigantic gravity well then I think it will start playing a game of Go and the borders will be void of space while matter and anti-matter will start clumping up together into groups. When a group of same polarity meets they merge when an opposite polarity meets they either cancel each other out or become more condensed due to edge repulsion. Through this process an interstellar cloud could collapse to form a planetary system.

I have the same objection: the M and AM would be so diffuse, with just a few particles per cubic centimeter at best, that collisions between particles and antiparticles would be rare and the "clouds" could intermingle extensively with very little exploding going on, and thus very little repulsion going on.

Imagine you have two groups of people coming toward each other. These groups hate each other, so whenever a member of group A comes close to a member of group B, they fight. They're not specifically looking to fight, just to go forward, but if someone gets in their way they'll fight them. If there are, say, a thousand of each coming toward each other along a narrow mountain pass or a bridge, there are going to be a lot of collisions and a lot of fights, and that "battle front" will keep the groups from intermingling much. But say you have a thousand of each spread out across the entire Mojave Desert -- maybe a mile between any two people in each group. The odds of a direct encounter between a member of group A and a member of group B are therefore tiny, and the groups will be able to walk right past each other and intermix with no resistance. A few close encounters may happen, sparking a few fights, but they'll be isolated and have little effect on any other people. They won't form a front that inhibits the movement of the groups.

 

[FredH]

Re: Is It Possible To Have Entire Planets Composed of Antima

Acknowledging right off the bat that it's probably impossible: For another interesting fictional example, Yukinobu Hoshino's manga series 2001 Nights had our sun turn out to have an antimatter "tenth planet." (This was many years before Pluto's demotion, of course, and before the discovery of Sedna, Quaoar et al.)

 

[SamuraiBlue]

Re: Is It Possible To Have Entire Planets Composed of Antima

Christopher said:

I have the same objection: the M and AM would be so diffuse, with just a few particles per cubic centimeter at best, that collisions between particles and antiparticles would be rare and the "clouds" could intermingle extensively with very little exploding going on, and thus very little repulsion going on.

Imagine you have two groups of people coming toward each other. These groups hate each other, so whenever a member of group A comes close to a member of group B, they fight. They're not specifically looking to fight, just to go forward, but if someone gets in their way they'll fight them. If there are, say, a thousand of each coming toward each other along a narrow mountain pass or a bridge, there are going to be a lot of collisions and a lot of fights, and that "battle front" will keep the groups from intermingling much. But say you have a thousand of each spread out across the entire Mojave Desert -- maybe a mile between any two people in each group. The odds of a direct encounter between a member of group A and a member of group B are therefore tiny, and the groups will be able to walk right past each other and intermix with no resistance. A few close encounters may happen, sparking a few fights, but they'll be isolated and have little effect on any other people. They won't form a front that inhibits the movement of the groups.

I understand what you are saying but wouldn't density within a proto-galaxy that has not developed any stars be be more uniform and closer to a nebula mostly consisting of gaseous material?
You'll have to consider gravity which also attracts particles regardless of polarity.

 

[Christopher]

Re: Is It Possible To Have Entire Planets Composed of Antima

SamuraiBlue said:
I understand what you are saying but wouldn't density within a proto-galaxy that has not developed any stars be be more uniform and closer to a nebula mostly consisting of gaseous material?

Yes, it would be uniform, but it would be uniformly as diffuse as I'm saying. After all, matter doesn't get less densely concentrated over time; as you yourself point out, gravity tends to draw it closer. A proto-galaxy's average density would no doubt be less than the current galaxy's average density.

It's hard for us to grasp how vast and empty space really is, because it's unlike anything in our terrestrial experience. You mention nebulae, and you're probably thinking of the TV/movie kind of nebula which is as dense as an Earthly cloudbank. But those are as inaccurate and fanciful as, well, just about everything else in mass-media sci-fi. A real nebula is a vacuum by our standards, thousands of times less dense than our atmosphere. Many nebulae are even less dense than the solar wind in interplanetary space within our system. They only look like thick clouds because we're so very far away from them.

You'll have to consider gravity which also attracts particles regardless of polarity.

And I already did, in an earlier post. I said that if such an intermingled cloud of particles and antiparticles were to begin to condense under gravity, its density would increase sufficiently for annihilation reactions to become more common, blowing it apart before any stars or planets could form. But the gravitational condensation would be a gradual process and would not occur before the matter and antimatter mediums had been able to intermingle as described in my previous post.

 

[Dayton3]

Re: Is It Possible To Have Entire Planets Composed of Antima

Could an antimatter planet form in a universe that was composed of only antimatter and then somehow get transported to our universe intact through some kind of singularity (black hole)?

 

[Christopher]

Re: Is It Possible To Have Entire Planets Composed of Antima

^^Too many ad hoc assumptions. We don't know if other universes even exist, or if wormholes exist.

Now, as I discussed above, there could be separate antimatter galaxies somewhere in the universe, conceivably. And it's conceivable that star systems could be ejected from a galaxy, drift across space for eons, and pass through or be captured by another. So I suppose that could result in an antimatter star system existing within a matter galaxy.

 

[Jarvis]

Re: Is It Possible To Have Entire Planets Composed of Antima

Dayton3 said:
Could an antimatter planet form in a universe that was composed of only antimatter and then somehow get transported to our universe intact through some kind of singularity (black hole)?

Only through a Morris-Thorne type wormhole but it involves so many guesses that we risk entering sci-fi territory.