Outline


Protons, neutrons, nuclei, elements and isotopes.

Primordial soup of the infant Universe.

Principles of Big Bang Nucleosynthesis.

Measuring the result:
Quasars as a back-light.
Spectral forest from ancient gas clouds.
Keck telescope and HIRES spectrograph.
Deuterium absorption lines.

What it tells us about amount of ordinary matter in our Universe.





Protons, neutrons, nuclei and isotopes

Nuclear fusion in stars

Back in time universe smaller denser, hotter

Beyond the last scattering surface

Start by assuming equal numbers of particles and antiparticles

"Temperatures" that can be probed by particle accelerators - Fermilab
pictures

Pair production and annihilation

Stretching space - reducing photon energy

proton-proton annihilation...
electron-positron annihilation

neutron decay

deuterium fragile - window for nucleosynthesis

D/H as indicator of baryon density

Measuring D/H in the local medium

D destroyed in stars

Measuring D/H in primordial gas clouds