Questions tagged [antimatter]

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

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What happens if we find out that antimatter particles “fall up”? [closed]

What happens if in this experiment we find out that antimatter "repels gravity", i.e., falls away from the earth? (Probably not gonna happen, our universe would never delight us with such a surprise) ...
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How sudden and how violent would the annihilation of a bowling ball of antimatter be?

Imagine that a bowling ball made of antimatter suddenly materializes inside a house. It will annihilate with the air, the table/floor or whatever it's on, and with other surrounding material. How ...
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Antimatter propulsion

I was reading about antimatter propulsion systems on the internet, and apparently they would work by letting matter and antimatter react and then the reaction would be (magnetically) channeled out ...
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What are the theoretical / mathematical problems in discarding negative solutions of Dirac equation?

I read some Q&A about it, but my question is why Dirac was so sure that he could not discard negative energy solutions. It seems so natural that energy must be positive, that I suppose that if ...
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Is there work done on a mass from matter-antimatter pairs?

Imagine I have a vaccuum at very low temperature and I put a single neutron in, then gamma rays interact to form matter-antimatter pairs within this vaccuum and assume that this happens extremely ...
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What would happen if our galaxy and an identical anti-matter galaxy annihilated each other?

What would happen if every bit of matter in our galaxy annihilated with an anti-matter equivalent at the same time? Such as that stars completely annihilated with identical antimatter stars, planets ...
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Gravity, matter vs antimatter

I have a simple question regarding matter-antimatter gravity interaction. Consider the following though experiment: If we imagine a mass $m$ and an antimass $m^-$, revolving around a large mass $M$ ...
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What are the minimum/realistic energies needed for positron/electron annihilation to form $D$ mesons?

High energy positrons and electrons can form $D$ mesons when they interact with each other and annihilate, but I was wondering what those energy levels would have to be. Specifically, would a fixed ...
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If neutrinos were their own antiparticles, would be observe a photon background from $\nu$-$\nu$ annihilations?

If neutrinos were their own antiparticles, would we observe a photon background from neutrino-neutrino annihilations? As neutrinos are so abundant, why don't we observe such a background? Is the ...
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Pressing questions about the annihilation of a particle & an antiparticle

A charged particle (e.g. proton) meeting with its own charged antiparticle (e.g., antiproton) annihilates and energy is given off in the form of radiation. Do we have any clue why this happens? Does ...
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Energy of the antiparticles

I would like to know how is it expressed antiparticles' energy. According to Tipler-Mosca's Modern Physics, Spin-$\frac{1}{2}$ particles are described by the Dirac equation, which is an extension ...
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What is the antiparticle corresponding to the left neutrino $\nu_L$?

What is the antiparticle corresponding to $\nu_L$ ? -According to this thread : What distinguishes the behaviour of particle from its antiparticle: C violation or CP violation? "The operation that ...
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Antimatter and quantum mechanics

This question could have a very simple answer but I could not find that answer anywhere. My question is since electrons, protons, etc they all have their antiparticles, why are not they mentioned in ...
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Would Majorana antinetrinos have opposite weak isospin?

There was a question about the difference between a neutrino and antineutrino, and answers suggested that weak isospin is different, as well as handedness. This would make sense if you expect pair ...
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Massive production of antimatter in industry

Would the massive (industrial) production of antimatter be possible? I am speaking of tons of antimatter, not only nanograms. I am speaking of an industrial process similar to the production of ...
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Dirac sea for Majorana equation

To resolve the problem of infinite energies, Dirac has proposed the conception of the Dirac sea. Is the same concept present for the case of Majorana spinors? How it is affected by the absence of ...
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Hawking Radiation Inverted [closed]

Regarding Hawking Radiation, if a particle - antiparticle pair forms with the particle within the event horizon, wouldn't the black hole increase in mass and appear to emit an antiparticle? Are the ...
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Can positrons emit photons like electrons do?

I am not asking about electron positron annihilation, nor positronium. Electrons (when accelerated in some cases non-uniformly), could emit photons. Though, I have not found any experiment that ...
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Weinberg's argument for antiparticles: is this really a necessary condition?

In Chapter 5 to "The Quantum Theory of Fields" by Weinberg he gives a nice point of view on antiparticles. He says the following (I've called the last equation (*) because it is not numbered in ...
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How to derive the wave function of an anti-particle

In second quantization, a field operator of e.g. an electron is given by $\Psi(\vec{r})=\sum_n \varphi_n(\vec{r}) \hat{c}_n$ with the operator $\hat{c}_n^+$ creating an electron within the state/...
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Experimental proof for the antineutron

An answer to the question How detectors in particle accelerators can differentiate neutrons from antineutrons do not show that an antineutron measurement was successful. The answers are from 2014 and ...
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Who first discovered the fact that matter and antimatter annihilate upon contact?

I cannot find (yet) a place that says who specifically theorized the mutual annihilation of matter and antimatter upon contact. I also don't know who first experimentally observed this phenomenon In ...
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Did Dirac anticipate not just the positron but also annihilation?

Would his equation have shown that annihilation would occur or did anyone know this before the actual discovery of the positron?
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How do photons create matter?

How exactly do photons create matter? I really have a hard time understanding this. I've seen an explanation where they use other, virtual particles to create electron and positrons, but even then, I ...
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How often do positrons appear in a typical Wilson cloud chamber?

I would like to know a rough estimate of how often positrons appear per meter cubed per second in a typical Wilson cloud chamber based off of your experience. I'm interested in the same quantity for ...
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Antimatter Storage

How would it be possible to store a large amount of antimatter (say, 1000000 kg) for a long amount of time (relatively speaking, like around 100 years, or long enough to travel to other systems in ...
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Quantum field theory, interpretation of commutation relation

Let $\phi$ be the quantum field $$ \phi(x) = \int \frac{d^3\mathbf{p}}{(2\pi)^3} \frac{1}{\sqrt{2E_\mathbf{p}}} \Big[ b_\mathbf{p}e^{-ip\cdot x} + c_\mathbf{p}^\dagger e^{ip\cdot x} \Big] $$ with ...
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Is there any different how we smash antimatter and matter together?

Imagine: Setup A, we smash relativistic electron at a stationery positron. Setup B, we smash electron and positron head on both moving at fraction of speed of light. Setup C, we allow electron to ...
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Conversion of mass into energy with 100% efficiency

Suppose you are given a mass of 1 kg. Einstein's theory of relativity says that all the mass can be converted into energy as per the equation $E = mc^2$. So if you want to convert this whole mass ...
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Is there a lepton anti-lepton asymmetry?

I dont know is this a stupid question or not but I wanted to ask We all familiar with the fact that there must be some more baryons w.r.t antibaryons. Since we do not observe any anti-baryons we ...
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How does an antiparticle respond to a gravitational field? [duplicate]

A related Wikipedia page provided a little overview. However, here's the question: If an anti-particle acquire a negative mass $m$ in QFT, doesn't $F=ma$ indicate that the anti-particle will ...
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Does antimatter have a quantum field?

I have a theory that all quantum objects have a quantum field but does anti-matter have a quantum field if it does not then does that mean it can only react through axions
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The Mathematical Prediction of Antimatter

According to my understanding: The Dirac Equation, has negative and positive energy solutions. The "Dirac Sea" theory says that these solutions can be interpreted as a "sea" of negative-energy ...
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A very naive question about Weyl spinor

Suppose we consider a left-handed Weyl spinor. Is its anti-fermion right-handed or still left-handed?
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Does annihilation differs from a pair production from two interacting particles?

By reading this: "Can two photons annihilate?" and answers to that question, I have came to strange question - Does annihilation in principle is different than a pair production process ? My intuition ...
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Do axions have an anti-particle?

Axions are the particles that let energy flash between a matter particle and its anti-particle. But according to quantum field theory, every particle has an anti-particle (besides the majorana fermion)...
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Why do antineutrinos have a spin of 1/2? [closed]

When the isotope Nitrogen-14 (which has a nuclear spin of 1) undergoes beta decay, it releases an electron, which has a spin of -1/2. Since the mass of the Nitrogen-14 isotope stays the same (albeit, ...
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Why more matter than antimatter and if so, how do we know this?

firstly, how do we know this? and secondly, would it not be possible that either antimatter and matter were produced in separate regions or randomly and if randomly it makes sense that in any given ...
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Why do antinuetrinos get emitted during beta decay?

Why do antinuetrinos get emitted, during Beta Decay? Can the existence of them be discovered mathematically (and if so, how?), or is their existence only proven, via empirical means?
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Why aren't black holes antimatter fountains?

As I understand it, nothing can escape a black hole because the only worldlines leading 'out' from the event horizon point backwards in time. As I understand it, antimatter is time-reversed ordinary ...
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Can anitmatter be scattered in other parts of time?

Is it possible that during the Big Bang, the matter and antimatter was scattered in the spacetime, along the time axis, as well, not just in space? (I am not sure, how to ask this properly, I hope ...
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A antimatter asteroid crashes into the Earth: Will a halo of γ rays protect the asteroid long enough to make it through the atmosphere?

This question comes from an interesting answer I received on Worldbuilding SE. The idea being that a fast moving antimatter object will react with the air molecules and produce gamma rays. These gamma ...
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What would the chemical and atomic effects of an antimatter star be upon a normal matter artificial planetoid? (Thought experiment)

Setting aside all the challenges of actually achieving such a thing, and as a thought experiment, what would the chemical and atomic effects of an antimatter star be upon a normal matter artificial ...
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What would the effect of an antimatter star be upon a normal matter planet? (Thought experiment)

Based on the answers from this question: Would the solar wind from an antimatter star be any different from a non-antimatter star?, it seems that an antimatter Sol type star would conduct fusion ...
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Could the matter-antimatter equivilance paradox be solved by inflation?

At the moment of the Big Bang, matter and antimatter should have been produced in the same amounts. However, we observe only matter and no antimatter leftover from that time. I was thinking that this ...
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Would the solar wind from an antimatter star be any different from a non-antimatter star?

Antimatter is any element of matter with an opposite charge than normal matter. As such, would an antimatter sun conduct fusion normally such that it would it radiate photons, or would it radiate ...
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Why is the Feynman propagator $\langle 0|T \phi(x) \phi^\dagger(y) |0 \rangle$ instead of $\langle 0 |T \phi^\dagger(x) \phi(y) |0 \rangle$?

If we expand a complex scalar field in terms of Fourier components, we can see that $\langle 0 |T \phi^\dagger(x) \phi(y) |0 \rangle$ contains terms which are not contained in $\langle 0|T \phi(x) \...
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What role does chirality play in annihilations?

I'm wondering what happens when particle-antiparticle pairs with different combinations of chiralities annihilate. How does it affect the outcome? Initially I was thinking: "Must a particle and its ...
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When does a particle have an antiparticle?

Though an electrically charged elementary particle is necessarily accompanied by an antiparticle, a particle need not be electrically charged to have an antiparticle. The cleanest example being a ...
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How scientists look for anti-matter?

If matter and anti-matter look exactly the same, then how can scientists look for anti matter from a distance (other galaxies)?

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