Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: Questions related to astrophysics

Learn more physics!

Most recent answer: 08/24/2010
Q:
Question related to astrophysics ….. 1)y is it said that the no of matter particles were more than that of the anti particles at the time of the big bang despite the fact that the pair of particle and antiparticle is produced from high energy photons as per what pair production explains……. So…Where does the extra particle come from……..??? 2) Similarly there was randomness in the spreading of matter so produced by the big bang though it is believed that initially mass was so much concentrated at the point that it turned all to energy or should say it was all energy concentrated at a point …… s o that the distribution of energy was uniform ( for a point it doesn’t matter….) then where are the randomness of distribution of mass come from such that the some regions were denser than other leading to gravity pulling them and making gas clusters and gradually other bodies……. 3) another elementary question…… it is said that a few seconds after the big bang , the subatomic particles gradually lost energy and came together…….then y the protons and neutrons came together first and not the electrons ………..this is possibly due to their greater mass….. but further diving them they are also made up of smaller units…… y they came together…….. the main question is y the smallest particles came together and turned to the form they are in now…… obviously at very very high energy of that time they could exist individually………then what were the forces that caused them to come together……. ??? thanks for ur time and efforts.........
- Apurva (age 17)
A:
You have very interesting and profound questions.  I'll try to answer them one by one.

1.  The matter anti-matter asymmetry is a well known and little understood problem.  Many prominent physicists have pondered it.  Andrei Sakharov studied it and described the necessary conditions for the asymmetry to exist, .   There might be separate areas in the universe that are anti-matter dominated.  They could even out the asymmetry. However in our local region of the universe observations have revealed none, since the boundary between matter and anti-matter should be prolific regions of annihilation radiation that we see no evidence of.  

2. The apparent randomness in observed matter density fluctuations:  stars, galaxies, galactic clusters etc., arise from the quantum mechanical fluctuations soon after the original big bang. These tiny perturbations then grow into large scale matter density fluctuations. Global mass distribution fluctuations tell us a great deal about the make-up of the early universe.  For example the mass of the elusive neutrino has been constrained by looking at large scale density fluctuations.  See: 

3. After the big-bang the growth and accumulation of nuclei, atoms, molecules, etc. is determined by the strength of the interactions as well as temperature of the constituents.  For example the elemental nuclei, hydrogen, deuterium, helium... are bound by the strong nuclear force.  Atoms, like hydrogen etc., are bound by weaker electrical forces, so have to wait around for a bit for the universe to expand a bit and cool down.

LeeH

(published on 08/24/2010)

Follow-up on this answer.