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

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How close does a particle-antiparticle pair need to be for annihilation to happen?

I've most often seen the statement that the annihilation of a particle and its antiparticle occurs when they 'collide' with one another. So in other words when they get very close to one another ...
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4answers
1k views

Neutron to antiproton decay

Would it be possible for a neutron to lose a positron and become an antiproton? Or would would it need to be the decay of an antineutron to antiproton instead?
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3answers
583 views

Is there a giant cloud of antimatter at centre of the Milky Way

Among others, this page says there is a giant cloud of antimatter at centre of the Milky Way, which was discovered in the 1970s. My brother doesn't believe there is any such cloud. I'm prepared to ...
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1answer
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Anti-Matter for Neutrons

The anti-particle corresponding to a proton or an electron is a particle with an equal mass, but an opposite charge. So what is the anti-particle corresponding to a neutron (which does not possess a ...
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2answers
251 views

Could the universe's antimatter be hiding in black holes?

As far as we know almost all the mass in the universe is matter, not antimatter. There are three scenarios: The universe started off with more matter than antimatter and the small amount of ...
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1answer
3k views

Exotic Matter — What is it?

I have a conceptual understanding of some theoretical physics concepts, so without getting into the math, what is exotic matter? I have read some articles that say it is anything not normal, while ...
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3answers
80 views

Matter and Antimatter (Hypothetical question) [duplicate]

What will happen if we somehow create an "anti-sodium "element and react it with "hydrogen"(not anti)? I am specific about ANTI-SODIUM and HYDROGEN. Not just plain matter and antimatter.
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1answer
627 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 ...
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1answer
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Is there any antimatter that exists as atoms?

I recently read a few things that implied that there is antimatter that we know of (have created?) that exists as atoms - which I guess means positrons and antiprotons bound together, at least. Is ...
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Why Negative Energy States are Bad

The argument is often given that the early attempts of constructing a relativistic theory of quantum mechanics must not have gotten everything right because they led to the necessity of negative ...
8
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1answer
503 views

How fast is the matter and antimatter reaction compared to nuclear chain reaction?

What I mean is, the nuclear chain reactions take microseconds for every generation and that is the reason that nuclear weapons exist. Because in nuclear reactors the reaction rate is much slower thus ...
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4answers
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If an anti-matter singularity and a normal matter singularity, of equal masses, collided would we (outside the event horizon) see an explosion? [duplicate]

If an anti-matter singularity and a normal matter singularity, of equal masses, collided would we (outside the event horizon) see an explosion?
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3answers
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Can antimatter be used as fuel for nuclear reactors?

I completely understand the difficulties of making and storing antimatter, so I am not talking about the mechanism or the way of doing it here, I am just talking about the concept. As far as I know, ...
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1answer
109 views

Equality of masses of particle and antiparticle

Usually we say that equality of masses of particle and antiparticle follows from CPT-theorem. But do we need it for showing this equality? The first method to show that is following. The equation ...
0
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1answer
173 views

Gravity and antimatter

If we put earth like planet made up of antimatter (same mass of earth, same diameter etc..) with same distance from moon as current distance between earth and moon then center of gravity of moon and ...
7
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1answer
399 views

Would matter-antimatter annihilation create a fireball or not?

There has been a long discussion between me and Anna V on if the products of the annihilation will really cause a fireball to form and we haven't settled it yet. Our point here is that gamma rays ...
4
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2answers
116 views

Questions about the strange character of antimatter

Its been a few days and i have just been introduced to the concept of antimatter. Every Speck of matter in the world has its anti form basically that we have antimatter whenever we have matter. But I ...
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2answers
392 views

Why is it called “annihilation”?

The term "annihilate" literally means "turn into nothing". However, when a particle and antiparticle collide, they clearly do not turn into nothing; they simply transform into different particles. ...
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2answers
1k 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 ...
3
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2answers
486 views

Can a neutron be created from pure energy

Is it possible to create a neutron out of pure energy, i.e. not by bringing a bunch of already-existing quarks together? (A quick calculation using E = mc2 shows the energy required would be about 1.5 ...
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0answers
103 views

Are we able to store low energy positrons in a magnetic field for arbitrarily long time?

And if not, what prevents us? Is there a mathematical equation describing the loss rate?
2
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1answer
403 views

Is the virtual photon a particle?

I just saw an exam question: Write down the antiparticle for the virtual photon. The answer was "virtual photon". Is the question even a meaningful one? If so please explain why?
2
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1answer
124 views

What would happen in a collision of an antimatter singularty and a matter singularity? [duplicate]

Would energy be released if a black hole made out of antimatter and another of matter were to collide?
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2answers
237 views

Matter vs. Antimatter shortly after Big Bang

I am not a physicist or astronomer in training at all, so this might be a dumb question with an obvious answer, but as I watched something the other day on matter & anti-matter, and the discussion ...
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2answers
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Would a matter-antimatter explosion cause fallout?

I know matter and antimatter annihilation release a lot of gamma rays which are considered ionizing radiation if I am not mistaken. But what if the explosion happened on the surface of the earth, ...
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4answers
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Schrödinger's equation, time reversal, negative energy and antimatter

You know how there are no antiparticles for the Schrödinger equation, I've been pushing around the equation and have found a solution that seems to indicate there are - I've probably missed something ...
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2answers
48 views

Are there different kinds of antimatter reactions?

Obviously, when matter and antimatter collide, they annihilate. But how exactly and are all reactions the same? For example, what happens when a molecule of hydrogen meets a single pion? Does the ...
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4answers
165 views

Can a positron decay without encountering an electron?

All the decays I read about involve electron - positron annihilation.
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4answers
131 views

Is there any evidence that matter and antimatter continuously appear and disappear on the edge of a black hole?

I heard Stephen Hawking got a Nobel prize for this, someone said there was no evidence for it which I find quite strange since he got an award for it.
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2answers
157 views

What distinguishes the particles we chose as matter from their antimatter equivalent? [duplicate]

Back before we knew about antimatter we just called everything matter. Ignoring CP-violation for a moment, there is nothing special about matter versus antimatter. Once we knew about antimatter it ...
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1answer
384 views

How to guarantee that a kilogram of antimatter will quickly annihilate another kilogram of matter?

What I mean is, suppose we could somehow get a kilogram of matter and contain it safely. Now lets say we want to make a bomb using this kilogram, now, we have two ways, either store another kilogram ...
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2answers
212 views

how do we know that the base of entire universe is the proton (hydrogen) and not the antiproton?

It may be that the base of a part of the world is anti-proton, We've always been on the planet Earth and the Milky Way. how do we know that the base of entire universe is proton (hydrogen atom)?
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0answers
82 views

Complete annihilation of matter-antimatter [duplicate]

Possible Duplicate: More on matter and anti-matter Everyone knows that when matter and anti-matter come in contact, they result in pure energy. I want to know that if atoms and anti-atoms ...
0
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1answer
49 views

How often does photons morph into matter and antimatter?

We know that matter-antimatter collisions are reducing the two into pure energy or photons. Similarly the reverse is possible where a photon can spontaneously morph into two equal particles of matter ...
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2answers
148 views

Particle anti-particle annihilation and photon production

This is just a conceptual question I guess. The annihilation of a particle with a finite mass and its anti-particle cannot lead to the emission of only one photon, and this is due to the conservation ...
0
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1answer
99 views

If one is talking about antineutron production, what is the charge exchange?

In this question was given the antineutron production in the way $$ p + \bar{p} \rightarrow n + \bar{n}. $$ Internet search gives one source only where the charge exchange is mentioned. They talk ...
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1answer
131 views

How to create antineutrons?

Creating a beam of antiprotons allows to create antineutrons by charge exchange. How does this exchange work? The question pops up after the question "Is there a strong evidence of antineutron ...
0
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1answer
84 views

What will happpen between a proton and an anti-neutron with unmatched color charges?

Maybe a stupid question because my search didn't return anything. Assuming in low energy state, a proton (made by a red up, a blue up and green down quarks) meets an anti-neutron (made by an ...
0
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1answer
151 views

Would an antimatter beam create multiple matter-antimatter explosions?

To expand upon the question - in an atmosphere, would a beam of pure antimatter (disregarding technical difficulties creating such a beam or passing it through a medium) interact with the matter in ...
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2answers
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What would happen after the collision matter and the anti-matter [duplicate]

Possible Duplicate: What actually happens when an anti-matter projectile collides with matter? Suppose 1 kg of a stray meteorite anti-matter moves to the earth. What would happen after ...