NATS 1740 Lecture Notes - Lecture 7: Big Bang, Redshift, Quantum Cosmology
19 May 2018
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NATS 1740
THURS, MARCH 23
M/C= 70 MARKS
10 MARKS FOR ARTISITIC IMPRESSION (correctness of language you are using)
50 FOR COMPLETENESS
EXPERIMENTAL SUPPORT FOR BIG BANG:
• .Hules galati easureet hih sho uierse is epadig
• 2.Background on microwave radiation
• 3. Confirmation from astrophysics of some of the big bang predictions
o ratio between hydrogen and helium abundance in the universe (hydrogen
protons changing into helium nuclei) 30% of hydrogen changed into helium
o theory of big bang justifies 25% conversion
o 5% sifference comes from stars
o so big bang in 200 seconds produced more helium thatn all the stars in the
universe in 13.7 billion years
HUBBLE DIAGRAM:
• hubble diagramgra horizontal is distance and vertical is galactic speed
o so the further the galaxies are, the higher the speed which illustrates and
accelerated exopansion if the speed increases all the time it smeans it is
accelerated
o accelerated means there is a force to create it, which was the big banf
• what is method that hubble used to determine speed and distance?
o Cepeid variables for distances
o LONGITUDAL SPEED = red shift
o Hubble determined speed of galaxy from red shift and the distance rrfom
epehedi airales ad thats here the error as
o Hubble diagram was wrong because age of universe predicted by hubble
diagram was shorter than age of earth
o Since 1952, we know the CORRECT way to use cephedi variabes and we know
that the hubble diagram works.
o Methods were imporved especially when dealing with galaxies very far awat
o Cepheid variables work up to 100 million light years
o Supernova 1a larger than 100 milllioni light years
find more resources at oneclass.com
find more resources at oneclass.com
Super strings:
Antiparticles:
• Problem is that there are not a lot of them
• We explain this based on the big bang
• The universe had an ASSYMETRY in the super weak force acting very early in the big
bang
• The asymmetry was related to the way in which antibarions became relative to barion
decay
• Anti barion is more probable
• This is why anti particles is less abundant in universe
• The few of them which exist annylate very quickly with existing particles
Guth inflation:
• WHY IS IT IMPORTANT: we need a uniform universe
• Distribution of supernova clusters is pretty uniform in universe
• If you simulate big bang without inflation, you will never get uniformity because
material will always go in a corner and rest will be empty
• 50 orders magnitude increase in a fraction of a second
RELATION TO STANDARD MODEL: agree on the six quart model
PROTON FUSION:
• in the big bang, proton fusion is about 200 seconds starting at about 10-3 seconds
• it takes 200 seconds to change 25% (one quarter of all the protons into helium
nuclei/alpha particles)
RADIATION SEPARATION:
• has to be cooler
• WHAT WILL SPOIL RADIAITON: radiation is used to create partciles so there is a cooling
off temperature when this cannot happen anymore
• Temperature of universe has to be 5000 degrees (around temperature of our surface of
sun)
• At this moment, radiation cools off separately from matter (particles with mass) and it
became in 13.7 billlion years the microwave radiation that is being observed toda
FORMATION OF ATOMS:
• 380,000 YEARS after big bang
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find more resources at oneclass.com
• we need so much time because the temperature has to be really cool for protons and
electrons and alpha particles to move slow so that the electrons can be captured by
protons to formed atoms
• if they just whisk by, they cant form atoms
• high temperature means high speed for particles and they will not form atoms
FORMATION OF STARS:
• 100 million years after big bang
• the furthest galactic observation is 13 billion years, but age of universe is 13.7 billion
years
• .7 biillion is 700 million years which is the beginning of star formation
• beginning was 100 million after big bang and by the time universe was 700 million years,
the galaxy was producing enough radiation to be observed today
• CR7 is the most remote galaxy
• Radiation coming from galaxies comes from stars but also from activity around the
gaglactic black holes
• The first quasars came later
our galaxy: 100,000 light years in size
WHAT ARE TWO POSSIBLE SCIENTIFIC ANSWERS TO THE QUESTION HOW THE UNIVERSE WAS
CREATED: (COSMOLOGY)
1.inflation theory
Quantum fluctuation in previous universe
2. M theory
-agrees with Aristotle that it was not created and it always existed
how matter appeared in universe:
1.Changing symmetry of universe from 11 dimensions to 4 dimensions
• In fraction of second changed from 11 to 4 and produced large amounts of particle with
a lot of weight
find more resources at oneclass.com
find more resources at oneclass.com
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NATS 1740 Full Course Notes
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Document Summary
10 marks for artisitic impression (correctness of language you are using) Experimental support for big bang: (cid:1005). hu(cid:271)(cid:271)le(cid:859)s gala(cid:272)ti(cid:272) (cid:373)easure(cid:373)e(cid:374)t (cid:449)hi(cid:272)h sho(cid:449) u(cid:374)i(cid:448)erse is e(cid:454)pa(cid:374)di(cid:374)g, 2. background on microwave radiation, 3. Guth inflation: why is it important: we need a uniform universe, distribution of supernova clusters is pretty uniform in universe. If you simulate big bang without inflation, you will never get uniformity because material will always go in a corner and rest will be empty: 50 orders magnitude increase in a fraction of a second. Relation to standard model: agree on the six quart model. Proton fusion: in the big bang, proton fusion is about 200 seconds starting at about 10-3 seconds it takes 200 seconds to change 25% (one quarter of all the protons into helium nuclei/alpha particles) Formation of stars: 100 million years after big bang the furthest galactic observation is 13 billion years, but age of universe is 13. 7 billion years.
