Analogous to matter, but with charge of the particles opposite to their ordinary matter counterparts.

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23
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3answers
3k views

How would we tell antimatter galaxies apart?

Given that antimatter galaxies are theoretically possible, how would they be distinguishable from regular matter galaxies? That is, antimatter is equal in atomic weight and all properties, except for ...
-2
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3answers
841 views

Andromeda is made of antimatter. Am I wrong? Why?

Andromeda is made of antimatter. Am I wrong? Why? Of course I do not know that Andromeda is made of antimatter. _but____ I do not know that Andromeda is made of matter. Does anybody know what is ...
4
votes
2answers
798 views

Is nature symmetric between particles and antiparticles?

Is nature symmetric with respect to presence of particles? Do we have an antiparticle for every particle thought of? Are there any proven examples where we don't have an antiparticle? And what about ...
8
votes
1answer
261 views

Why is the decay of neutral kaons (violates CP invariance) seemingly not sufficient enough for certain people to describe matter-antimatter imbalance?

The Nobel Prize in Physics in 1980 was awarded to James Cronin and Val Fitch for their discovery of a violation of Charge and Parity Invariance, in which the neutral kaon's quarks change into their ...
3
votes
2answers
249 views

Are there any differences between photons emited /absorbed by antimatter atoms to photon in usual atoms?

(Theoretically) Are there any differences between photons emited /absorbed by antimatter atoms to photon in usual atoms? for example, is it impossible to tell the difference between a photon emmited ...
1
vote
2answers
231 views

self-antiparticles and broken symmetries

certain particles (i.e: certain bosons like the photon) do not have an anti-particle, or rather, they are they own anti-particles. lets assume that such symmetry is only approximate and these ...
7
votes
4answers
7k views

What is the pure energy in matter antimatter annihilation made of?

I used to read the term "pure energy" in the context of matter antimatter annihilation. Is the "pure energy" spoken of photons? Is it some form of heat? Some kind of particles with mass ? ...
1
vote
3answers
675 views

Anti-matter repelled by gravity - is it a serious hypothesis? [duplicate]

Possible Duplicate: Why would Antimatter behave differently via Gravity? Regarding the following statement in this article: Most important of these is whether ordinary gravity attracts ...
5
votes
3answers
987 views

Why would Antimatter behave differently via Gravity?

Confinement of antihydrogen might help provide a future answer. http://arxiv.org/abs/1104.4982
8
votes
3answers
2k views

Does a particle annihilate only with its antiparticle? If yes, why?

Or to put the question another way - what is the result of a proton-positron collision, or an up quark-charm antiquark collision, etc.? As far as I know, annihilation happens only between particles of ...
2
votes
2answers
773 views

When matter and anti-matter collide

Do they create energy? Or do they just disappear with zero energy? If they create energy when disappearing, that means it takes energy to create them, right? If they disappear into zero energy, ...
15
votes
3answers
1k views

No hair theorem for black holes and the baryon number

The no hair theorem says that a black hole can be characterized by a small number of parameters that are visible from distance - mass, angular momentum and electric charge. For me it is puzzling why ...
8
votes
3answers
2k views

What actually happens when an anti-matter projectile collides with matter?

I'm trying to understand what would really happen when large quantities (e.g., 10g) of anti-matter collide with matter. The normal response is that they'd annihilate each other and generate an ...
2
votes
2answers
388 views

How does slow anti-hydrogen annihilate with normal matter in the lab?

In a recent article: Physical Review A 83, 032903 (2011), A.Yu. Voronin, P.Froelich, V.V. Nesvizhevsky, Antihydrogen Gravitational Quantum States the authors claim that anti-hydrogen has a lifetime ...
13
votes
5answers
553 views

Matter-Antimatter Asymmetry in Experiments?

As I hope is obvious to everyone reading this, the universe contains more matter than antimatter, presumably because of some slight asymmetry in the amounts of the two generated during the Big Bang. ...
7
votes
1answer
2k views

Electric charge in string theory

The mass of an elementary particle in string theory is related with the way the string vibrates. The more frantically a string vibrates the more energy it posses and hence the more massive it is. My ...
1
vote
4answers
395 views

Is “real” antimatter (odd under C, P, T) unphysical?

A positron is odd under charge conjugation and parity reversal but nevertheless even with respect to time reversal. Is a theoretical positron which would be odd under all three symmetries (C, P, T) ...
8
votes
2answers
679 views

Practical uses of antimatter in the present

I recently found out that a PET scan stands for a positron emission tomography. Are there any other practical uses of antimatter in the present?
17
votes
1answer
587 views

In general what will holding an anti-hydrogen atom for more than a 1/10th of second allow scientists to discover?

In general what will holding an anti-hydrogen atom for more than a 1/10th of second allow scientists to discover? Specifically, given that they can hold one for <1/10th of a second, what would ...
23
votes
2answers
529 views

Experimental observation of matter/antimatter in the universe

Ordinary matter and antimatter have the same physical properties when it comes to, for example, spectroscopy. Hydrogen and antihydrogen atoms produce the same spectroscopy when excited, and adsorb the ...
37
votes
7answers
25k views

Is anti-matter matter going backwards in time?

Or: can it be proved that anti-matter definitely is nót matter going backwards in time? From wikipedia: There is considerable speculation as to why the observable universe is apparently almost ...