Astrophysics in the Early Universe Ingredients of the Primordial Soup

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Astrophysics in the Early UniverseIngredients of
the Primordial Soup

• Brian Fields
• Departments of Astronomy and Physics, UIUC
• U of I Astronomical Society Nov. 30, 2004

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From the Home Office in Shampoo-Banana...
Top Three Pillars of the Big Bang Cosmology

• Expansion of Universe
• t 13 x 109 yr 13 billion yr

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Cosmology

• Structure, Origin, Evolution of the Universe
• stars organized into galaxies
• ex Solar Sytem is part of Milky Way
• Typical galaxy 100 billion stars

Andromeda galaxy
Sombrero galaxy
Think big! galaxies are building
blocks smoothly fill universe (like dust)
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Edwin P. Hubble

• The great observer of galaxies
• Measured galaxy
• Distance
• Speed

Hubble, the man
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Its 1928.Hubble is measuring galaxy
velocities, distances.What will Edwin find?

• More galaxies approaching than receding
• More galaxies receding than approaching
• About equal numbers of each

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Hubbles Law and Its Meaning

• Edwin Hubble (1929)
• galaxies moving away from us
• farther faster
• that is, v D
• v HD

• Interpretation What does it mean?

• Egoist
• view
• We are at
• center of Universe

• Einstein
• view
• Universe is
• expanding!
• No center!

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AGE OF UNIVERSE
Expansion implies finite age
If constant speed, distance speed x time D vt

• Hubble v HD
• D distance between 2 particles (galaxies)

All together v HD H(vt) Htv so Ht
1 expansion age of universe
t1/H
best estimate age t 13 billion years
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A Telescope is a Time Machine
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A Telescope is a Time MachineThe Hubble Deep
Field

• Farther away means
• Takes light longer to get to us
• Light seen now started long ago
• Most distant Universe 10 present age!

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Questions so far?
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Words of the great Cosmologist Woody Allen
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From the Home Office in Shampoo-Banana...
Top Three Pillars of the Big Bang Cosmology

• Expansion of Universe
• t 13 x 109 yr 13 billion yr
• Cosmic Fireball Released
• t 100, 000 yr

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EXPANDING UNIVERSE THE PAST

• U. expanding today
• galaxies closer in past
• more dense

• long ago, very dense
• matter in contact energy, heat flow
• Universe has temperature

• dense compressed heat up
• Expand cool
• Early Universe very dense and very hot

BIG BANG
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INTERLUDE I LIGHT HEAT

• hot objects glow
• light, heat connected
• thermal radiation

Spread out into colors spectrum

• color wavelengths where brightest
• depends on temperature
• color-temperature connection (think flame!)

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TAKING THE TEMPERATURE OF THE UNIVERSE

• Penzias Wilson (1964)
• entire sky bright with microwaves

• spectrum is thermal, with
• the temperature of space"
• ...extremely cold today

Nobel Prize!
the Universe filled with thermal radiation
Cosmic Microwave Background Radiation
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FROM ATOMS TO THE COSMOS

• Microwave background radiation observed
• what does it tell us?
• when was it created?

• To answer follow microscopic behavior
• atoms in expanding Universe

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INTERLUDE II ATOMS IN A NUTSHELL

• Atoms made of
• electrons - charge
• nucleus protons charge, neutrons 0 charge
• neutral equal p and e
• bind" together, stable
• ionized some or all e gone
• not bound, less stable
• To ionize need energy to un-bind
• tear away electron
• Cold gas gentle collisions neutral
• Hot gas violent collisions ionized

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THE COSMIC FLAME

• At present Universe extremely cold neutral
  atoms
• In past Universe hotter
• when T _at_ 3300 K 5500F
• whole universe ionized
• in primeval fireball

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THE COSMIC FOG CLEARS

• When universe ionized opaque
• But universe cooled
• until t _at_ 300, 000 yrs
• collisions gentle neutral
• universe transparent
• atoms formed pe hydrogen
• microwave background is
• faded snapshot of cosmic fireball
• when ionized neutral
• Big bang model works well
• back to t 300 000 yrs !

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From the Home Office in Shampoo-Banana...
Top Three Pillars of the Big Bang Cosmology

• Expansion of Universe
• t 13 x 109 yr 13 billion yr
• Cosmic Fireball Released
• t 100, 000 yr
• Light Elements Born
• t 1 sec

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THE NUCLEAR AGE

• In Atoms
• electrons bound to nuclei
• need energy (high T) to remove
• In Nuclei protons, neutrons bound together
• by nulcear forces strong
• to break apart need very high energy
• very high T
• At t lt 1 sec
• T gt 1010 K 10 billion degrees
• nuclei totally ionized
• only p and n exist

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BIRTH OF THE LIGHT ELEMENTS

• At T 1 billion degrees
• nuclear ionization stops
• nuclear reactions proceed rapidly

• Big Bang Prediction
• Fill Universe w/ lightest elements
• Hydrogen, Helium, Lithium
• Example 24 He

• Astronomical Observations
• Measure light elements in near and distant sites

CONCORDANCE!

• Theory can explain all observations
• Theory Vindicated!
• Big Bang working well back to t 1s!
• earliest probe of Universe!
• take my word
• lite elements cosmic n and p content

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THE FUTURE
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EXPANDING UNIVERSE FINAL FATE

• Competition gravity vs inertia
• Compare pop fly!
• quantitative question
• launch speed vs speed to escape Earth
• For Universe
• gravity galaxy mass density
• inertia expansion
• Both are observable!
• Fate quantitative question
• if expand forever
• if expansion halts, collapse

or
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BBN AND DARK MATTER

• Big bang nuke measures density of
• anything made of protons neutrons
• all ordinary matter

• Light element observations

• Consequences
• if normal is all, expand forever
• Can measure luminous matter (stars, gas)
• most normal matter dark baryonic dark matter
• Can estimate total matter content
• most matter not normal! non-baryonic dark matter
• exotic particles?

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ORIGIN OF DARK MATTERTHE VERY EARLY UNIVERSE?

• Maybe Dark Matter particles created at times ltlt
  1 sec !?
• T, energies ultrahigh
• Q how probe such high energies?
• Hint its in the Great State of Illinois
• Fermilab

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INNER SPACE / OUTER SPACE

• Fermilab is a telescope!
• Probes conditions in
• Universe at 10-12 s
• but also
• The Universe is the poor mans accelerator
• Probes conditions inaccesible at laboratories

Russian cosmologist Yakov Zeldovich
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OUTLOOK

• PRESENT
• Big bang theory in great shape
• tested from t 13 billion years 4 x 1017 sec
• down to t 1 sec
• NEAR FUTURE
• New era dawning for Cosmology
• flood of high precision data
• right now Golden Age!
• old questions answered
• new questions emerge
• new tools available
• Exciting, expansive future!
• Room for you to join the fun!

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How can I join the fun?Two Words Astronomy
Major!

• From the Home Office in Urbana, IL...
• Top Ten Reasons to Major in Astro
• 10. integrates all areas of physics (many double
  majors Phys/Astro!)
• 9. also geology, chemistry, biology
• 8. flat central Illinois more sky to look at!
• 7. develop critical thinking, problem solving
• 6. get all of Douglas Adams' inside jokes
• 5. two words Hubble telescope
• 4. better at parties than Accounting
• 3. pretty pictures are homework
• 2. be part of golden age
• cosmology, black holes, extrasolar planets
• 1. it's fun!