What Role Did Electrons and Positrons Play in the Early Universe?

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In summary, the conversation discussed the early universe and the role of electrons and positrons in it. It was confirmed that a dominant part of the early universe consisted of electrons and positrons, and there were processes through which they gained mass. The balance in numbers of electrons, protons, and neutrons was also explained, with the understanding that the universe has zero total charge and charge is conserved. The concept of particles with mass being created from pure energy was also discussed, and it was clarified that this process is not quantum mechanical. The conversation also touched upon the creation of other particles and the role of annihilation in the early universe. Lastly, it was suggested that reading "The First Three Minutes" would
  • #1
narrator
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I've been reading about the early universe (The book: The First Three Minutes) and it prompted a few questions:

Is it right that a dominant part of the early universe was electrons and positrons?

Given that electrons and positrons were a big part of the early universe, was there some early process whereby they ended up becoming masses (or just the positrons did)? I'm trying to understand how the balance in numbers of electrons, protons and neutrons came about.

I find it difficult to get my head around a particle having no mass (photons). Is it that their mass is so insignificantly small, compared to protons and neutrons, that their mass has no measurable effect? Or is it that they actually do have zero mass?

Edited to correct something I misread. Apologies.
 
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  • #2
narrator said:
Is it right that a dominant part of the early universe was electrons and positrons?
I think that's right: http://en.wikipedia.org/wiki/Lepton_epoch

narrator said:
Given that electrons and positrons were a big part of the early universe, was there some early process whereby they ended up becoming masses (or just the positrons did)?
Electrons and positrons do have mass. Particles with mass can be created out of pure energy: E=mc2.

narrator said:
I'm trying to understand how the balance in numbers of electrons, protons and neutrons came about.
The universe has zero total charge, and charge is conserved. One example of a mixture of particles that has zero total charge is a mixture of electrons, positrons, neutrinos, and photons (as in the lepton epoch). Another example is a mixture of protons, neutrons, electrons, neutrinos, and photons (the part of today's mix that we understand well). Mix #1 existed at early times because the temperature was high enough to produce electron-positron pairs spontaneously.

narrator said:
I find it difficult to get my head around a particle having no mass (photons). Is it that their mass is so insignificantly small, compared to protons and neutrons, that their mass has no measurable effect? Or is it that they actually do have zero mass?
Empirically, we can set a very low limit on their mass:
R.S. Lakes, "Experimental limits on the photon mass and cosmic magnetic vector potential", Physical Review Letters 80 (1998) 1826, http://silver.neep.wisc.edu/~lakes/mu.html
Note that massless particles still gravitate, basically because their energy is equivalent to some mass by E=mc2. There was an era when gravity in our universe was mainly due to photons: http://en.wikipedia.org/wiki/Radiation-Dominated_Era

-Ben
 
  • #3
Thanks Ben, thanks for your comprehensive reply. :)

bcrowell said:
The universe has zero total charge, and charge is conserved.

Do we know this for certain? My memory of chemistry is that unstable chemicals change often because of movement of uneven charges. (I recall some man made chemicals were difficult to maintain for this reason.) Could it be that the BB had some provocation from such an imbalance?

bcrowell said:
Particles with mass can be created out of pure energy: E=mc2.

I've often wondered about this process. Is it quantum machinery that does this? (Trying to form a picture in my mind of how it might happen - energy pushing quantum particles together or some such.)

bcrowell said:

I noted from the link in that article to Leptons, this quote: "Charged leptons can combine with other particles to form various composite particles such as atoms and positronium."

Which made me wonder. If Leptons were the dominant species, then there were fewer "other particles" at that time. Which means more "other particles" must have been created by the process you mentioned, mass out of energy. Is that right? Was that the annihilation process?
 
  • #4
narrator said:
Do we know this for certain? My memory of chemistry is that unstable chemicals change often because of movement of uneven charges. (I recall some man made chemicals were difficult to maintain for this reason.) Could it be that the BB had some provocation from such an imbalance?
http://en.wikipedia.org/wiki/Charge_conservation

narrator said:
I've often wondered about this process. Is it quantum machinery that does this?
No, it's a purely classical (i.e., non-quantum mechanical) fact.

narrator said:
Which made me wonder. If Leptons were the dominant species, then there were fewer "other particles" at that time. Which means more "other particles" must have been created by the process you mentioned, mass out of energy. Is that right? Was that the annihilation process?
The main change has not been that leptons and antileptons have been annihilated with each other.

The questions you're asking make me think you could get a lot out of reading The First Three Minutes.

-Ben
 
  • #5
bcrowell said:
The questions you're asking make me think you could get a lot out of reading The First Three Minutes.

hehe.. I'm reading it, a dozen pages at a time.. but you're right
 

FAQ: What Role Did Electrons and Positrons Play in the Early Universe?

What are "No mass *trons" and "early mass" in the context of science?

"No mass *trons" and "early mass" are terms used in particle physics to describe hypothetical particles that do not have any mass, or have very little mass, and are believed to have existed in the early universe during the Big Bang. These particles are currently not proven to exist, but are being studied by scientists to better understand the fundamental building blocks of the universe.

How would the existence of "No mass *trons" and "early mass" affect our understanding of the universe?

If these particles were to be discovered and proven to exist, it would greatly impact our understanding of the universe and its origins. It would provide further evidence for the Big Bang theory and help explain the processes that occurred in the early stages of the universe's formation.

Why are scientists interested in studying "No mass *trons" and "early mass"?

Scientists are interested in studying these particles because they could potentially help bridge the gap between the theories of gravity and quantum mechanics. They could also provide insight into the nature of dark matter and dark energy, which are still largely unknown to scientists.

How do scientists search for evidence of "No mass *trons" and "early mass"?

Scientists use a variety of methods to search for evidence of these particles. Some of these methods include experiments at particle colliders, studying the cosmic microwave background radiation, and analyzing data from the Large Hadron Collider.

What are the potential implications of the discovery of "No mass *trons" and "early mass"?

If these particles were to be discovered, it could open up new possibilities for scientific advancements and technologies. It could also lead to a better understanding of the origins of the universe and potentially help solve some of the biggest mysteries in physics.

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