Lec 23 Revision and questions Flashcards
(9 cards)
Why isn’t the universe more akin to a black hole, if it was condensed into a singularity?
Black holes are more empty space with a vacuum solution. All the mass of the black hole is at the singularity center
Our expanding universe has matter everywhere and is mathematically different from black holes. Time is dependent on universes while it’s not in a black hole. While our universe does have a cosmological horizon from expanding, it changes as the universe expands (unlike in a black hole with an event horizon).
How does so much matter fit in a singualrity?
Initial singularity - the “zero size” of the universe when time = 0
Since the 1980s, models of cosmology o ther very early universe (within the first 10 ^-36 seconds) show the universe undergoing early period of accelerated expansion (inflation).
All the energy and matter at the singular point with an initial volume less than a single proton. Inflation expands it enough to account all mass in the universe
What is inflation?
Inflation - explains the oddities involving the initial state o the universe (e.g. similar critical and actual densities, why the universe is smooth on a large scale, and the seeds that grow into galaxies come from)
How bright and hot was the Big Bang/ early universe?
Evidence from CMB, Planck astonomy, and photons:
Microwave backgrounds show that the universe had intense heat and light. CMB discovered in 1965 by Robert Wilson and Arno Penzias using the Bell Telephone Lab.
More evidence of the intense heat from Planck astronomy - the study of CMB (the relic radiation formed early in the universe) and other astrophysical phenomena through planck satellites.
Used to help understand the origin, evolution, and structure of the universe.
Billions of photons from each proton that stretch by expansion (redshift). Show that the early universe was hotter than todays (enough to naturally have nuclear reactions).
Anything before the BB?
Not definitive, but something like the “initial singularity” was the origin of infinite density and temperature followed by the Planck epoch (the time immediately following the singularity).
Some models think the Big Bang might have been a consequence of quantum fluctuations, so the quantum field would have had to precede it.
Why ddi the BB happen? What other theories are there?
Why? - No one really knows why as its just a theory and not an event.
Alternate theories think the Big Bounce occurred, which suggests a cyclical universe with periods of expansion and contraction with “rebirth” rather than a true beginning.
When did the BB happen? What evidence is there?
When - theorised about 13.8 billion years ago. Evidence from:
Redshift light of the furthest distance of galaxies
CMB - the faint radiation of the big Bang afterglow that can estimate the age of the universe
The high ratio of Hydrogen and Helium
Ages of old stars and other celestial objects that can be carbon dated up to 13.8 billion years.
how did initial galaxies form?
Initially tiny density fluctuations amplified by cosmic inflation created pockets of denser areas. Overdensity pulled more matter leading to formation of small dense objects taht merged and grew into initial galaxies.
Inside these proto-galaxies, gas cooled and collapsed into suns, planets, etc.
What evidence is there that we are living in a strange SS?
Rarest structure - Ordered STructure, where the mass of planets seems to sequentially increase with distance to sun
Unusually large number of planets and complex Moons
Larger distance of inner planets, and the existence of an asteroid belt
Presence of liquid water
Gas giant size, composition, and distribution is not super common
Life and Intelligence
Unusually high elements creating our planets (likely from merging neutron stars)
