# First Particles

1. Feb 12, 2010

### cbd1

I have read "The First Three Minutes" and all of the information about the Big Bang on Wikipedia, but I cannot find through either of these sources the newest theory of the first particles to arise after the Big Bang. Is it possible that one particle may have been first? Also, I am interested in real particles, as opposed to virtual particle-antiparticle pairs, which would all destroy and leave nothing behind. There must have been particles made that were not in such virtual particle pairs in order for there to be any particles remaining today.. What do we know about this?

2. Feb 12, 2010

### mathman

This is one of the puzzles of the big bang, since current theory does not have any excess of particles at the big bang. The general theory about why we have particles is that there is a slight difference in decay properties between particles and antiparticles. However, the details are incomplete.

3. Feb 12, 2010

### BillSaltLake

Although how they came into being is not known, there is a reasonable chance that a slight excess of neutrons (one neutron per 1.7 x 109 photons) existed just after 10-6 sec. At earlier times, the photon energy was too high for neutrons to be stable for any significant fraction of the age at the time.

4. Feb 13, 2010

### Chalnoth

Basically you need a significant violation of what is known as the CP symmetry: charge plus parity. We already know of some very small violations of CP symmetry through the weak nuclear force, but those violations aren't large enough to explain the asymmetry of matter/anti-matter in the early universe. For more on this, you may want to take a look at the Wikipedia article:
http://en.wikipedia.org/wiki/CP_violation

Note that this really isn't an issue of distinction between virtual and real particles, because there is no clear distinction between them.

5. Feb 13, 2010

### Anti-Meson

Ok here is the load down on the big bang:

1. Between $$10^{-43}$$ s and $$10^{-32}$$ s quarks, neutrinos are created.
2. Between $$10^{-6}$$ s and $$255$$ s nucleons are formed: neutrons and protons.
3. Between $$10^{3}$$ s and $$10^{13}$$ s basic ions are formed : Hydrogen and Helium.
4. Between $$10^{13}$$ s and $$10^{15}$$ s neutral atoms form.
5. Between $$10^{15}$$ s and the present day: stars and galaxies are formed and evolving.

Just to put a scale on this a billion years is $$10^{16}$$ s so it has taken just under 100 million years for atoms to form.

References: pp1542-1543 University Physics, Young & Freedman.

Last edited: Feb 13, 2010