Big bang related question

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In summary, during the early stages of the universe after the big bang, matter and antimatter were created in equal proportions. However, the majority of this matter-antimatter pair annihilated, leaving only a small fraction of matter behind. The annihilation was mostly between quarks and antiquarks, and the initial asymmetry between them was not significant. During the hadron and lepton epoch, protons, neutrons, and their respective antiparticles were annihilated among each other. This occurred after the QCD phase transition, following baryon formation.
  • #1
Deepak247
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Ive heard that soon after the big bang matter and antimatter was created in equal proportions and that majority of the matter-antimatter annihilated among each other, somehow only a small fraction of matter remained... my question is...

what was the form of the matter or antimatter which was annihilated?

was it mostly in baryons or mesons? i.e. mostly baryons annihilating among each other or mesons annihilating among each other?

what was the ratio?
 
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  • #3
ok but how much was proton-antiproton and neutron-antineutron annihilation there?

i mean to say baryon annihilation...was it significant?
 
  • #4
As I said, there was annihilation between quarks and antiquarks -- not baryons. The initial asymmetry between quarks, [itex]q[/itex], and antiquarks, [itex]\bar{q}[/itex] was in fact not significant:
[tex]\frac{n_q - n_{\bar{q}}}{n_q} \simeq 10^{-8}[/tex]
 
  • #5
  • #6
Yes, that is correct. Sorry, I was mistaken. The initial asymmetry was setup during baryogenesis, prior to baryon formation; the annihilations occurred between baryons after the QCD phase transition.
 

1. What is the Big Bang theory?

The Big Bang theory is a scientific explanation for the origin of the universe. It suggests that the universe began as a singularity, a point of infinite density and temperature, around 13.8 billion years ago. This singularity then expanded rapidly, creating all matter and energy in the universe.

2. How was the Big Bang theory discovered?

The Big Bang theory was first proposed in the 1920s by astronomer Georges Lemaitre, who noticed that the universe was expanding. This idea was further supported by observations made by Edwin Hubble in the 1920s and 1930s. In the 1960s, the discovery of cosmic microwave background radiation provided additional evidence for the Big Bang theory.

3. What evidence supports the Big Bang theory?

There are several lines of evidence that support the Big Bang theory, including the expansion of the universe, the abundance of light elements, and the existence of cosmic microwave background radiation. Additionally, the Big Bang theory can also explain the large-scale structure of the universe and the distribution of galaxies.

4. What is the role of dark matter and dark energy in the Big Bang theory?

Dark matter and dark energy are two components of the universe that are believed to make up the majority of its mass and energy. While their exact nature is still unknown, they play a crucial role in the Big Bang theory by providing the necessary gravitational pull to allow for the expansion of the universe.

5. Does the Big Bang theory explain how life began?

No, the Big Bang theory does not explain how life began. It only explains the origin and evolution of the universe. The origin of life is still a subject of ongoing scientific research and is not directly related to the Big Bang theory.

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