Particle production in an expanding universe?

In summary, the conversation discusses the possibility of particle production in an expanding universe, specifically in the current accelerating phase. While particle production from high energy photons is rare, the article focuses on "cosmological particle creation" by dynamic spacetimes. The article also mentions the potential impact of an equation of state with ##w<-1##, known as phantom matter, on particle production. So far, observations support a value of ##w=-1##, indicating very small particle production in the current universe. The validity of this "cosmological particle creation" is still being researched and is not yet confirmed by observations.
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Particle production in an expanding universe?
I was reading this interesting article [1] which talks about particle production in an expanding universe.

Usually this process is proposed to have occurred in the early universe, when the expansion was in the inflationary phase and it was so powerful that matter was created in particle production mechanisms.

However, can particles be produced in an accelerating expanding universe like our current one? Can particles be produced by the universe's expansion with the current conditions of our own one?[1]: https://iopscience.iop.org/article/10.1088/1361-6633/ac1b23
 
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In general particles are produced from pairs of high energy photons. Extremely rare these days.
 
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Suekdccia said:
However, can particles be produced in an accelerating expanding universe like our current one? Can particles be produced by the universe's expansion with the current conditions of our own one?[1]: https://iopscience.iop.org/article/10.1088/1361-6633/ac1b23

mathman said:
In general particles are produced from pairs of high energy photons. Extremely rare these days.
Actually, pair production by photons is not the type of particle creation about which the articles talks. The article is about "particle creation" by dynamic spacetimes, something like a cosmological version of Hawking radiation.

From the arXiv version: page 18 "After inflation has ended, and the universe has entered a radiation or a matter dominated epoch, gravitational particle creation would normally be expected to become very small, as the spacetime curvature has become relatively small, and the expansion time correspondingly large."; page 19 "Another context in which quantum particle creation could become important in the late universe would if the effective equation of state of the matter in the universe were of the form ##p=w\rho##, where ##w<-1##, sometime called phantom matter. The equation of state causes such rapid expansion that curvature singularity arises, the 'Big Rip'"

So far, observations are consistent with ##w=-1##, which gives very very small particle production for the current accelerating phase of the universe.
 
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George Jones said:
Actually, pair production by photons is not the type of particle creation about which the articles talks. The article is about "particle creation" by dynamic spacetimes, something like a cosmological version of Hawking radiation.

From the arXiv version: page 18 "After inflation has ended, and the universe has entered a radiation or a matter dominated epoch, gravitational particle creation would normally be expected to become very small, as the spacetime curvature has become relatively small, and the expansion time correspondingly large."; page 19 "Another context in which quantum particle creation could become important in the late universe would if the effective equation of state of the matter in the universe were of the form ##p=w\rho##, where ##w<-1##, sometime called phantom matter. The equation of state causes such rapid expansion that curvature singularity arises, the 'Big Rip'"

So far, observations are consistent with ##w=-1##, which gives very very small particle production for the current accelerating phase of the universe.
Even if at small rates, is this "cosmological particle creation" supported by mainstream and verified physics?
 
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Suekdccia said:
Even if at small rates, is this "cosmological particle creation" supported by mainstream and verified physics?
Do you consider Hawking radiation to be mainstream and verified?
 
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I'd say Hawking radiation is "mainstream" but not observed yet.
 
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1. What is particle production in an expanding universe?

Particle production in an expanding universe refers to the creation of new particles as the universe expands. This phenomenon is a result of the conversion of energy into matter, as predicted by Einstein's famous equation, E=mc^2.

2. How does the expansion of the universe affect particle production?

The expansion of the universe leads to a decrease in the density of particles, which in turn affects the rate of particle production. As the universe expands, the energy density decreases, and therefore the production of particles also decreases.

3. What types of particles are produced in an expanding universe?

In an expanding universe, various types of particles can be produced, including photons, electrons, protons, and neutrons. These particles are created through different processes, such as pair production and nucleosynthesis.

4. Can particle production in an expanding universe be observed?

Yes, particle production in an expanding universe can be observed through various experiments and observations. For example, the cosmic microwave background radiation, which is a remnant of the early universe, provides evidence for the production of particles during the Big Bang.

5. How does particle production in an expanding universe contribute to the evolution of the universe?

Particle production plays a crucial role in the evolution of the universe. As particles are created, they interact with each other and form more complex structures, such as atoms, stars, and galaxies. These structures then continue to evolve and shape the universe as we know it.

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