Are there antimatter galaxies?

Are there antimatter galaxies?
Wyoming Milky Way set. Credit: Randy Halverson

One of the biggest mysteries in astronomy is the question, where did all the antimatter go? Shortly after the Big Bang, there were almost equal amounts of matter and antimatter. I say almost, because there was a tiny bit more matter, really. And after the matter and antimatter crashed into each other and annihilated, we were left with all the matter we see in the Universe.

You, and everything you know is just a mathematical remainder, left over from the great division of the Universe's first day.

But is it possible that the antimatter didn't actually go anywhere? That it's all still there in the Universe, floating in galaxies of antimatter, made up of antimatter stars, surrounded by antimatter planets, filled with antimatter aliens?

Aliens who are friendly and wonderful in every way, except if we hugged, we'd annihilate and detonate with the energy of gigatons of TNT. It's sort of tragic, really.

If those antimatter galaxies are out there, could we detect them and communicate with those aliens?

First, a quick recap on antimatter.

Antimatter is just like matter in almost every way. Atoms have same atomic mass and the exact same properties, it's just that all the charges are reversed. Antielectrons have a positive charge, antihydrogen is made up of an antiproton and a positron (instead of a proton and an electron).

It turns out this reversal of charge causes regular matter and antimatter to annihilate when they make contact, converting all their mass into pure energy when they come together.

Credit: Universe Today

We can make antimatter in the laboratory with particle accelerators, and there are natural sources of the stuff. For example, when a neutron star or black hole consumes a star, it can spew out particles of antimatter.

In fact, astronomers have detected vast clouds of antimatter in our own Milky Way, generated largely by black holes and neutron stars grinding up their binary companions.

But our galaxy is mostly made up of regular matter. This antimatter is detectable because it's constantly crashing into the gas, dust, planets and stars that make up the Milky Way. This stuff can't get very far without hitting anything and detonating.

Now, back to the original question, could you have an entire galaxy made up of antimatter? In theory, yes, it would behave just like a regular galaxy. As long as there wasn't any matter to interact with.

And that's the problem. If these galaxies were out there, we'd see them interacting with the regular matter surrounding them. They would be blasting out radiation from all the annihilations from all the regular matter gas, dust, stars and planets wandering into an antimatter minefield.

Astronomers don't see this as far as they look, just the regular, quiet and calm matter out to the edge of the observable Universe.

That doesn't make it completely impossible, though, there could be galaxies of antimatter as long as they're completely cut off from regular matter.

Are there antimatter galaxies?
The ALPHA experiment, one of five experiments that are studying antimatter at CERN Credit: Maximilien Brice/CERN

But even those would be detectable by the supernova explosions within them. A normally matter supernova generates fast moving neutrinos, while an antimatter supernova would generate a different collection of particles. This would be a dead giveaway.

There's one open question about antimatter that might make this a deeper mystery. Scientists think that antimatter, like regular matter, has regular gravity. Matter and antimatter galaxies would be attracted to each other, encouraging annihilation.

But scientists don't actually know this definitively yet. It's possible that antimatter has antigravity. An atom of antihydrogen might actually fall upwards, accelerating away from the center of the Earth.

Physicists at CERN have been generating , and trying to detect if they're falling downward or up.

If that was the case, then antimatter galaxies might be able to repel particles of regular matter, preventing the annihilation, and the detection.

If you were hoping there are lurking out there, hoarding all that precious future energy, I'm sorry to say, but astronomers have looked and they haven't found it. Just like the socks in your dryer, we may never discover where it all went.


Explore further

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Source: Universe Today
Citation: Are there antimatter galaxies? (2016, June 10) retrieved 17 October 2019 from https://phys.org/news/2016-06-antimatter-galaxies.html
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Jun 10, 2016
On an antimatter planet in an antimatter galaxy when the inhabitants empty their dryer wouldn't they say. "Where did all these extra socks come from?"

If so would't dryers be the link between matter and antimatter galaxies. Maybe it is the anti-static dryer sheets that create the connection.

:-)

Martin

Jun 10, 2016
I have already seen the anti-matter but I can't show you because you can't see it

Jun 10, 2016
Antihydrogen doesn't clump together in dense magnetically bound clouds like hydrogen does. This prevents there from being large concentrations available to create stars, galaxies and clusters based on antimatter.

Jun 10, 2016
"One of the biggest mysteries in astronomy is the question, where did all the antimatter go?"

It didn't go anywhere. The tangible matter in the universe consists primarily of only positive and negative electrons.

Jun 10, 2016
"One of the biggest mysteries in astronomy is the question, where did all the antimatter go?"


It didn't go anywhere. The tangible matter in the universe consists primarily of only positive and negative electrons.
..............shhhhhhh, not so loud or you'll be accused of raining on the Dark Matter parade by it's most loyal Enthusiasts who live here.

Jun 10, 2016
@Benni Ha! maybe anti-matter galaxies have Dark anti-matter halos

Jun 10, 2016
...antimatter planets, filled with antimatter aliens...


You could not enter their atmosphere nor could they enter yours, so you can't meet (their atmosphere must be antimatter as well).

But as the photon is its own antiparticle, so to speak, we could communicate via electromagnetic media as light has the same properties in both the matter and antimatter galaxies...just don't let Scottie beam you down...

Jun 11, 2016
Antimatter matters. There is a boardgame of the same name. Actually very fun and good science info.

Jun 11, 2016
Antimatter is created in Earths upper atmosphere during thunderstorms. It is then collected by the magnetosphere and encircles the planet. So it is not so alien and distant

Jun 12, 2016
If there were blobs of anti-gravity material distributed homogeneously with blobs of ordinary gravity matter, would the whole thing not inflate?

Closer inspection into the cosmic voids might be needed.

Jun 13, 2016
This story sure brought out a lot of nerd humor, or what nerds think is humor. I wish there was some other site to which they could post.

Jun 13, 2016
The problem with postulating antimatter galaxies is that they would have to be surrounded by clouds of antihydrogen; and where the antihydrogen met the ordinary hydrogen surrounding matter galaxies, there would be detectable annihilation. We'd be able to see it. And we don't.

It's worth running an experiment to test whether antimatter responds oppositely to gravity, but it's very unlikely; as @Phys1 points out, energy is what matters with gravity, not mass, and we already know that antimatter has positive energy because otherwise matter-antimatter annihilation wouldn't yield energy, the matter and antimatter would just disappear into nothing. This will just be another test confirming GRT.

Jun 15, 2016
Matter and anti-matter or more precisely a reversal of orbiters, obviously offers greater instability; or shall we say, as you call, annihilation! However, the centers of the spherical fields still exist as well as all it's movement, i.e. response. Obviously, since the choice of + or - is arbitrary, the only requirement of which would be a function of the controlling motion, faster become orbiters. Suspect , population dependent, the choice spreads due simply upon total counts. However, the exact dynamics may be defined from the spectrum. Uncontrolled turbulence will always decrease, the rate determines relative energy.

Jun 15, 2016
@Da Schneib&Phys1 Yes I would think so too. I mean, take e- and e+ annihilation into gamma rays, where one would expect an 'anti-gamma' photon if anti-matter were fundamentally structured with different energy type (er....is that right?). As far as I'm aware photons are their own anti-photon. Could DM 'shield' an anti-matter galaxy?

Jun 16, 2016
@Da Schneib&Phys1 Yes I would think so too. I mean, take e- and e+ annihilation into gamma rays, where one would expect an 'anti-gamma' photon if anti-matter were fundamentally structured with different energy type (er....is that right?). As far as I'm aware photons are their own anti-photon. Could DM 'shield' an anti-matter galaxy?

You don't get it. The gamma is the action when an inverted orbiter enters a field of normal orbiters. The high frequency oscillation, or gamma, is due to the very close proximity of very fast moving spherical fields. Do the math an stop inventing impossible $hit as some mystery to be uncovered. The mysteries and magic are only in your head. I say this kindly. Somethings are blatantly obvious. But one must think in the 21st century, not the 19th. Photons, really? define the shape and surface and the material that makes it. Can we get a bunch of photons and put then in a bag and take them to lunch to show your teacher?

Jun 16, 2016
I mean, take e- and e+ annihilation into gamma rays, where one would expect an 'anti-gamma' photon if anti-matter were fundamentally structured with different energy type

Photons are their own antiparticle, so no: we always expect to see photons.
Note that if antimatter had 'anti energy', 'anti mass' or 'anti gravity' (which all are essentially saying the same thing) then we wouldn't see any photons at all in an annihilation event. However we do, so it's a good bet that antimatter has positive gravity. Not a final verdict, but that's the one I'd expect to come out from future measurements.

Could DM 'shield' an anti-matter galaxy?

Since DM has positive gravity: no. By the above it would attract an antimatter galaxy just like it would a matter galaxy.

Jun 16, 2016
@antialias_physorg Yes, see you point about DM, thanks

Jun 17, 2016
@antialias_physorg Yes, see you point about DM, thanks

Photons do not exist.

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