Chapter 17 Flashcards
do forces unify at high temperatures? why?
yes! from particle accelerators
describe plank era..
time: <10^-43 s
- we lack theory to describe conditions in the Plank era
- ALL forces may have been unified
when did GUT era begin?
gravity became distinct from other forces
When did GUT era end?
when strong force became distinct from electroweak force
What is the highest time the Era of Nucleosynthesis can go?
5 minutes
In the era of nucleosynthesis, nuclei began to fuse what?
hydrogen, helium, and trace amounts of lithium
in the era of nucleosynthesis there was no what?
helium fusion, only hydrogen fusion
why was there no helium fusion in the era of nucleosynthesis?
because the temperature and density dropped too low for helium fusion to occur
what was the era of nuclei’s time?
from 5minutes -380,000 years
era of nuclei’s temperature?
10^9 -3000 Kelvin
how do we observe the radiation left over from the big bang?
-the cosmic microwave background (the radiation left fro the big bang was detected by Penzias and Wilson in 1965)
since when has cosmic background radiation been streaming across the universe?
since atoms formed at 3000K. (visible/infrared)
Whats the perfect thermal radiation spectrum temperature?
2.73 K (heat of the universe)
expansion of the universe had ________ thermal radiation from that time to 1000times longer wavelenght
redshifted
whats the minimum percentage of HE in a galaxy?
25
