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8
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269 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 ...
3
votes
1answer
125 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 ...
5
votes
2answers
212 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 ...
3
votes
1answer
115 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} ...
1
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1answer
90 views

Can a positron beam cut through metal?

Can a positron beam be used to cut through metal?
1
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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 ...
3
votes
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 ...
5
votes
1answer
147 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 ...
0
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1answer
125 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 ...
1
vote
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 ...
0
votes
1answer
98 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, ...
1
vote
2answers
110 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 ...
7
votes
2answers
337 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 ...
0
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1answer
307 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 ...
7
votes
3answers
219 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), ...
19
votes
5answers
1k views

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 ...
25
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1answer
373 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 ...
0
votes
2answers
154 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, ...
0
votes
1answer
147 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 ...
0
votes
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 ...
1
vote
1answer
192 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 ...
3
votes
1answer
209 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 ...
1
vote
1answer
219 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 ...
5
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1answer
197 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 ...
2
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2answers
1k 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, ...
6
votes
2answers
305 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 ...
7
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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 ...
1
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3answers
933 views

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, ...
1
vote
1answer
86 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 ...
7
votes
1answer
215 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, ...
7
votes
1answer
294 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 ...
2
votes
2answers
248 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 ...
1
vote
1answer
128 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 ...
6
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1answer
223 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 ...
0
votes
1answer
100 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 ...
1
vote
1answer
174 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. ...
0
votes
1answer
110 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 ...
0
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2answers
155 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 ...
1
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2answers
124 views

Could the outer structure of the Universe be made from Antimatter?

Cern recently stated that antimatter may be repelled by matter, much like the opposite effect of Gravity. So is it possible that antimatter is actually repelled to the edges of the Universe to create ...
0
votes
1answer
213 views

Strings and QFT: particles moving backward in time?

New question: In string theory and QFT, do particles travel back in time? Not related to antimatter: Do they travel back and forth in time in reality or are these just interpretations of mathematical ...
2
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1answer
110 views

Antimatter in the universe [duplicate]

Is it possible that some parts of the universe contain antimatter whose atoms have nuclei made of antiprotons and antineutrons, sorrounded by antiprotons? If yes what can be the ways to detect this ...
1
vote
1answer
231 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 ...
2
votes
2answers
272 views

How much energy is carried away by neutrinos in matter-antimatter annihilation?

Some people say that neutrinos carry away most of the energy, some others say just a fraction. So what is the truth ? what is the percentage of energy lost due to neutrinos ?
8
votes
1answer
292 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 ...
0
votes
1answer
54 views

Gravitational potential energy with regards to annihilation

Given particles A, B, C and D, where: A and B have an equivalent mass C and D have an equivalent mass, both larger than A (or B) D is the antiparticle of C. A and B start close to C, but with ...
0
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2answers
163 views

Effect of mass matter-antimatter annihilation? [duplicate]

Possible Duplicate: What actually happens when an anti-matter projectile collides with matter? If a large amount of antimatter is suddenly released or launched in the open and expands, ...
-1
votes
1answer
67 views

Could much of the “missing” antimatter make up neutrons?

A neutron can decay into a proton, an electron, and neutrino. Could an antiproton, a positron, and a neutrino combine into a neutron? Could this be where much of the "missing" antimatter is?
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3answers
305 views

Do particle pairs avoid each other? Please end my musings

Can you explain what happens when a particle and its antiparticle are created. Do they whiz away from each other at the speed of light or what? I suppose that they don't because otherwise they would ...
0
votes
1answer
55 views

When is the FAIR accelerator supposed to be finished? [closed]

The FAIR accelerator is a planned facility for antiproton and ion research. Ground water wells are being put in, the forest is being cleared... But when is it supposed to be completed? Does anyone ...
3
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2answers
68 views

heavy nuclei surface exposed to positron gas

Suppose there is a material with heavy nuclei attached on its surface, presumably binded by the outer shell electrons. Now, the surface is exposed to a cold positron gas, which annihilates against ...