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

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137 views

Neutron-Antineutron creation/annihilation data

What is the most precise data for neutron-antineutron production by one photon (hitting a target in the laboratory system)? and/or What is the most precise data for neutron-antineutron annihilation ...
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43 views

anti-matter activation energy

In chemical reactions, there are usually energy barriers that must be overcome before a reaction can take place. It seems that such a phenomena also exists at the atomic level as well. For instance, ...
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0answers
33 views

antimatter moving back in time [duplicate]

This just blew my mind away! I was watching a video about imagining the fourth dimension and the narrator said that little line. Can some people elaborate on this. Also please keep it simple not ...
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0answers
23 views

It's commonly said that the existence of antiparticles “saves causality”. How? [duplicate]

The way I've always thought about is something like this: If measurements of space and time are essentially indeterminate (indeterminacy principle), then an entity "traveling at less than the speed of ...
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2answers
94 views

Could Gamma ray bursts be caused by matter-antimatter annihilation?

As far as I know a collisions of matter and antimatter leads to the complete annihilation of both, whereby 100% of the rest mass of the particles is converted into gamma rays. Could this mechanism be ...
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2answers
126 views

Neutrinos and anti-neutrinos in the Standard Model

In standard model neutrinos and the left handed electron forms SU(2) doublet. What about the anti-neutrinos in the standard model? Do they also form some doublet? If neutrinos have tiny masses will ...
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6answers
2k views

Is there any way to annihilate matter without the use of anti-matter?

Is there any way to annihilate matter without the use of anti-matter? And vice versa? I mean, for example is it possible to totally convert the mass of a proton into "pure energy" without use an ...
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1answer
69 views

What is the difference between the process in which energy converts to matter and that in which it converts to antimatter?

What is the difference between the process in which energy converts to matter and the process in which it converts to antimatter? In colliders, for instance, is the product (either being the matter or ...
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1answer
106 views

Little confusion in drawing Feynmam diagram

If the arrows of both the outgoing solid lines of the Feynman diagram corresponding to the bhabha scattering of $e^+$ and $e^-$, are just reversed, will it not describe same thing? Doesn't both imply ...
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100 views

Is there there is another universe which is made up of antimatter, in large amounts like ours is made up of matter?

Can it be possible that in the big bang, not one, but two universes were formed, one formed of matter, and the other formed of antimatter? It seems logical to me that since our universe is formed of ...
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1answer
160 views

How to think about antiparticles in KG equation?

I am a beginner to study QFT and have a problem. I know, in Dirac equation, thanking to the Pauli exclusion principle and believing that the vacuume is the state that all the negative energy states ...
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33 views

Why is it more likely that the particle with negative mass falls into a black hole? [duplicate]

If particle-antiparticle pairs pop into existence at the event horizon, and presumably their orientation to the black hole is random, why is it the particle with negative mass is more often (always?) ...
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283 views

How come the universe is made of matter and not antimatter?

Antimatter is like matter on opposite day: it has the same properties as the stuff that makes up planets, stars and galaxies, but one vital piece is different—its charge. The universe supposedly ...
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1answer
128 views

Quantum Field Theory and antiparticles vs particles

Does a particle and its antiparticle share the same field in QFT? If an electron is an energized spot in the electron field, is a positron a less energized spot or even a spot of negative energy (if ...
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2answers
246 views

Why does the spiral of a positron have a larger radius than that of an electron in this picture in a bubble chamber?

The smaller spiral is caused by an electron The bigger spiral is caused by a positron However, they have the same mass and magnitude of charge. So, during this pair production, why does the positron ...
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1answer
118 views

Sign of mass of an anti-particle

When deriving the Lagrangian for Spin $\frac{1}{2}$ particles we are naturally led to using $\Psi$ and $\bar{\Psi}$. The Euler-Lagrange equations lead us to two wave equations: \begin{equation} ...
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1answer
90 views

Can a positron beam cut through metal?

Can a positron beam be used to cut through metal?
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0answers
82 views

Dirac representation between matter and anti-matter

If $|\psi \rangle$ represents a wavefunction through a column matrix and $\langle \psi |$ represents the dual vector in a row matrix and $|\psi \rangle \langle \psi | = \rho $ is the probability ...
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2answers
162 views

Can path integral paths go backwards in time?

The paths can cross any coordinate at any time in the whole space (e.g. Universe space). Integration goes over all could-you-imagine paths. But time goes strictly forward. Can time variable resemble ...
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1answer
148 views

QED and Newton's 3rd law

According to some lecture notes on propagators (see bottom of page) the Feynman particle/anti-particle hypothesis states: The emission (absorption) of an antiparticle of 4-momentum $p^\mu$ is ...
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1answer
126 views

Need for acceleration in particle-antiparticle annihilation? [closed]

If an electron and positron are accelerated towards each other, at distances quite far away, there wouldn't be any significant electrostatic attraction, hence they need to be accelerated. But when ...
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1answer
42 views

Lifetime of Positron and its existence

Since we know in condensed matter the lifetime of positron is about 10^-10 seconds, how do we collide positrons with electrons? How many positrons were there during the LEP experiment? I know ...
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1answer
103 views

What happens when half of an orbiting object's matter is annihilated?

Suppose object A orbits object B, and that there are no outside gravitational influences non-Sun gravity influences, and that object A is completely spherical and its mass is evenly distributed. Now, ...
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2answers
116 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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2answers
374 views

Anti-matter as matter going backwards in time? (requesting further clarification upon a previous post)

I understand this question has already been asked here, however, I don't have enough reputation points to place a comment (I suppose that's the reason) on a specific answer to request a reference. A ...
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1answer
314 views

If time travel to the past is not possible why is this situation considered in Feynman diagrams?

I recently read R.P Feynman's QED:A Strange Theory of Light and Matter. It is believed that time travel to the past is not possible. Then why is particles going backward in time considered in the book ...
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240 views

Are there models/simulations of antigravitational antimatter-galaxies?

In the comments to another question's answer, I started wondering: Assuming antimatter possessed negative gravitational mass§ (which is not proven impossible to date, though deemed unlikely), ...
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Does antimatter curve spacetime in the opposite direction as matter?

According to the Dirac equation, antimatter is the negative energy solution to the following relation: $$E^2 = p^2 c^2 + m^2 c^4.$$ And according to general relativity, the Einstein tensor (which ...
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399 views

Identification of particles and anti-particles

The identification of an electron as a particle and the positron as an antiparticle is a matter of convention. We see lots of electrons around us so they become the normal particle and the rare and ...
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2answers
160 views

Big Bang, What is wrong with such thinking? [closed]

Also if I think the Expanding of Universe like this: At the Start : The Amount of Matter and Anti-Matter is equal and they annihilate and all we had is Large Amount of energy. But some 'X' Thing, ...
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1answer
154 views

Antimatter collision - Energy Released

I think it's about time for me to ask this question, as I've been contemplating this for a while. $$E = mc^2.$$ This is Einstein's most famous equation. But what does it mean? On my own, I had to ...
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1answer
61 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 ...
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1answer
211 views

Are multi-megaton antimatter induced fusion explosions theoretically possible?

I just finished reading this research about antimatter induced fusion and thermonuclear reactions. And one conclusion I could make is that very little mass of antimatter (in range of micrograms) is ...
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219 views

Weak interaction and the Chirality of anti-particles

Consider a weak current of the form $ J^{\mu} = \bar{u}_{\nu}\gamma^{\mu}(1-\gamma^5)u_{e} $ This describes the part of a weak process where a left-handed electron converts into a left-handed ...
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1answer
233 views

How is the energy distributed in a proton-antiprotion annihilation?

I know the products of the annihilation, but I don't know how much energy each particle has or gets. For example I know that 1876 MeV is released for each annihilation. Now, this energy is distributed ...
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235 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 ...
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2k views

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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2answers
324 views

What is the percentage of useful energy do we get from matter-antimatter annihilation?

This is a theoretical question since we haven't made enough antimatter to try it in reality of course. But I am asking about the physics part in this. Also, by "useful energy" I mean the energy we ...
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3answers
2k views

If atoms never “physically” touch each others, then how does matter-antimatter annihilation happen?

It is known that matter and antimatter annihilate each others when they "touch" each others. And as far as I know, the concept of "touching" as our brain gets it is not true on the atomic level since ...
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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
87 views

What determines the charge of an electron? [closed]

So I am thinking of making a machine that turns electrons into positrons. So you put as many electrons as you want in one side and positrons come out the other side. This will solve all out energy ...
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223 views

Baryogenesis only at the Planck scale, or none at all?

I can think of three general ways of explaining why the universe contains more matter than antimatter: (1) Near the Planck time, the universe had zero baryon asymmetry, but at some later time, ...
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1answer
327 views

Antimatter Propulsion System

Is there a possibility ( in theory ) to build a antimatter propulsion system, if so how can we control the collision of matter-anitmatter, will humans be able to control this force just like ...
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2answers
262 views

Matter and anti-matter collision energy problem

From Beyond Einstein, by Michio Kaku and Jennifer Thompson, Chapter 13, Antimatter : Dirac, also focused on the fact that Einstein's equation $E=mc^2$ wasn't totally true. (Einstein was aware that ...
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1answer
134 views

Quarks and anti-quarks forming particles [duplicate]

As I know, when particles and anti-particles come close, they anihilate. So somthing caused me a big trouble : how can particle formed by quarks and anti-quarks can exist? I've just found some mesons ...
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1answer
267 views

Could electrons be a form of antimatter?

I've played with this idea for years, and haven't really been able to eliminate it. So, perhaps someone here can point to simple experimental evidence that would do so. Here's the issue: Antimatter ...
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1answer
104 views

Can you fuse Anti-matter atoms?

I know that this is a simple question, but I could not for the life of me find a source that explains fusion for Anti-matter atoms. intuitively, I can say that there shouldn't be any barrier for ...
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1answer
177 views

Anti-particle problem for Dirac sea

According to the Dirac hole theory we know that Dirac sea is completely filled with negative energy, called vacuum. We will need $2mc^2$ or greater to get electron and a positron by incident photon. ...
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115 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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158 views

What if the antimatter in the center of our galaxy could annihilate and cause a chain reaction?

Being said that the antimatter - matter reaction is faster than that of a fission and fusion, what if the antimatter cloud found at the center of our galaxy could really able to react with matter from ...