Anti galaxies

[anderscolingustafson]

I think there is a definite possibility that half of the galaxies in the observable universe and beyond are made entirely out of antimatter.

Although matter and antimatter annihilate each other when they touch it may be possible that the matter and antimatter are kept separate by gravity. It is possible that the gravity of matter and antimatter repel each other. Antimatter gravity would attract anti matter but it's possible that it would repel matter and vice versa. It's possible that part of the acceleration of the expansion of the universe is due to the gravity of matter and antimatter. This would seem to also make since because when matter and antimatter collide their mass equals zero since all of it is converted into energy.

Since the only difference between matter and antimatter is the charge of the proton and electron and possibly opposite kinds of gravity we would never know that an antimatter galaxy was made of antimatter unless some of it's antimatter was to collide with matter.

The probability of there just by chance being one in a hundred million more particles of matter than of antimatter seems extremely unlikely considering how many particles there are in the universe. It seems more that each particle rather matter or antimatter had a one in 200,000,000 chance of making it to the region of space were its kind of matter was collecting.

So perhaps if we ever do go to another galaxy that is not gravitationally bound to the milky way we should go in a space ship that has a magnetic field that repels antimatter, and if we land on a planet in one of those galaxies we should wear a magnetic suite that is designed to repel antimatter just in case the planet is made of antimatter so that we don't blow up part of the planet.

[quickfur]

This should go in the General forum, not here.

[hosj]

When all of the matter in the universe was crunched up at the big bang, then wouldn't the future material for your anti-galaxies be destroyed by normal matter? Negative mass exists, and posses anti-gravity, but that is totally different then anti-matter which is just particles with opposite charge but the same spin.

[Teragon]

We can be quite sure that the galaxies in the observable universe are all largely made of normal matter. Otherwise giant flashes of light would dominate the night sky, when matter and antimatter annihilate each other in the steady process of galaxy growth. It is also not true that both together have zero mass. Both matter and antimatter have a positive (relativistic) mass, which is just converted into a different form in the process of annihilation.

[Prashantkrishnan]

We would have to redefine the law of gravitation for that.

The behaviour of negative mass according to Newton's law is quite interesting. Positive masses attract each other while negative masses repel each other. A positive mass would flee from a negative mass, while the negative mass chases it.

[Foxbat_25]

THat's quite the interesting topic, sorry if I'm necroposting but this is fascinating. So, if a negative and a positive mass were to chase each other like this, would they push each other permanently, or would they end up either coming in contact or drifting too far away from each other for gravitation to have an effect?
Because this does sound like a way to achieve permanent motion.

[개구리]

Not only would they chase each other forever, they would continue accelerating with no energy input, perhaps even past the speed of light because relativity only disallows momentum from increasing beyond the speed of light limit. Of course, negative mass doesn't exist, that's totally silly. What does that even mean? You can't design meticulous equations to describe reality, and then put a negative sign here and a square root there (regardless of how sensible this would be for the variables) to come up with serious possibilities for what else lies out there.
Actually, the word "mass" is bad, because no modern scientist has ever properly and consistently defined the term.

[wendy]

Antimatter is essentially a mirror-image of matter. The thing is still subject to gravity as a positive mass, and still is positive under E=mc².

What happens is that if one supposes that matter is a knot tieing up energy, then antimatter is the reverse of the knot tieing up energy. When the two knots come together, they unravel and release the energy as a pair of photons. So, for example, when a positron and electron collide, they release two photons, each 511000 volts equiv, which is the combined masses of the two particles.