A Brief History of the Universe Flashcards
what are two pieces of evidence for the Big Bang?
1) expansion of the Universe
2) cosmic microwave background
the universe in earlier times was what two characteristics?
much denser and hotter than today
what were three things existent right after Big Bang?
quarks and leptons and radiation
what happens when a particle meets its anti particle?
mutual annihilation…producing two gamma ray photons
the mass and energy of the universe was dominated by what?
radiation
what are baryons?
quarks confined in groups of 3…held together by strong force
what make up nearly all baryons today?
protons and neutrons
what happened during nucleosynthesis?
universe was hot enough to allow for fusion reactions to synthesize the light elements
photons outnumber baryons ___ to ___
billion to 1
what caused the universe to become transparent to light?
recombination….electrons combined w/ nuclei forming neutral atoms
slightly denser regions grow slowly due to what?
gravity
does dark or ordinary matter grow more rapidly?
dark matter
galaxy formation is hierarchical, Meaning what?
small to large
when we are looking out into space, what are we technically doing?
looking back in time
major mergers of disk galaxies can produce what kind of galaxies?
elliptical galaxies
rate of star formation over time?
was much greater in the past, peaked about 10 billion years ago
“fine-tuning problems” of the Big Bang?
1) horizon problem
2) flatness problem
what is the “horizon problem”?
why is the CMB so uniform?
what is the flatness problem?
why is the universe so flat?
what solved the two Big Bang fine tuning problems?
the idea of inflation
