PHYCS 199B Oct 29 2002

Physics in the Early UniverseIngredients of the Primordial Soup: 

Physics in the Early Universe Ingredients of the Primordial Soup Brian Fields Department of Astronomy, UIUC Physics Careers Oct 29, 2002

Astrophysics: 

Astrophysics Physics on a grand scale

Astrophysics: 

Astrophysics Unique Challenges: Experiment (black hole engineering still a ways off…) Instead: Astronomical observation “You can look but you can’t touch” Windows on the Cosmos: Observing across the EM spectrum xxxxxxxxxxxx Visible (Keck, Hawaii) Radio (BIMA, California) X-Ray (Chandra)

Astrophysics: 

Astrophysics A symphony of physics topics: The real universe uses mechanics, E&M, quantum physics, elementary particle physics, thermodynamics, relativity, … all at once! Extreme environments black holes, exploding stars, big bang: unique testing grounds for new physics! “The Heavenly Laboratory!” 2002 Nobel Prize in Physics Neutrino, X-ray Astrophysics!

Today’s Specialat the Astrophysics Cafe: 

Today’s Special at the Astrophysics Cafe The Physics of the

From the Home Office in Shampoo-Banana...: 

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

Slide7: 

Structure, Origin, Evolution of the Universe stars organized into galaxies ex: Solar Sytem is part of Milky Way Typical galaxy: 100 billion stars Cosmology Andromeda galaxy Sombrero galaxy Think big! galaxies are building blocks smoothly fill universe (like “dust”)

Edwin P. Hubble: 

Edwin P. Hubble The great observer of galaxies Measured galaxy Distance Speed Hubble, the man

It’s 1928.Hubble is measuring galaxy velocities, distances.What will Edwin find?: 

It’s 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

Hubble’s Law and Its Meaning: 

Hubble’s 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!

AGE OF UNIVERSE: 

AGE OF UNIVERSE Hubble: v = HD D: distance between 2 particles (galaxies) t=1/H Expansion implies finite age All together: v = HD = H(vt) = Htv so: Ht = 1 “expansion age” of universe If constant speed, distance = speed x time D = vt best estimate: age t = 13 billion years

A Telescope is a Time Machine: 

A Telescope is a Time Machine

A Telescope is a Time MachineThe Hubble Deep Field: 

A Telescope is a Time Machine The 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!

From the Home Office in Shampoo-Banana...: 

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

EXPANDING UNIVERSE: THE PAST: 

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

INTERLUDE I: LIGHT & HEAT: 

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!)

TAKING THE TEMPERATURE OF THE UNIVERSE: 

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 the Universe filled with thermal radiation Cosmic Microwave Background Radiation

FROM ATOMS TO THE COSMOS: 

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

INTERLUDE II: ATOMS IN A NUTSHELL: 

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

Slide21: 

THE COSMIC FLAME At present: Universe extremely cold: neutral atoms In past: Universe hotter when T @ 3300 K = 5500F whole universe ionized in primeval fireball

Place Your Bets: 

Place Your Bets Put flame in light beam: how appear on screen? Darker (casts shadow) Brighter (adds own light) Same brightness (it's a wash)

THE COSMIC FOG CLEARS: 

THE COSMIC FOG CLEARS When universe ionized: opaque But: universe cooled until t @ 300, 000 yrs collisions gentle: neutral universe transparent atoms formed: p+e hydrogen microwave background is faded snapshot of cosmic fireball when ionized neutral Big bang model works well back to t = 300; 000 yrs !

From the Home Office in Shampoo-Banana...: 

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

THE NUCLEAR AGE: 

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 < 1 sec T > 1010 K = 10 billion degrees nuclei totally “ionized” only p and n exist

BIRTH OF THE LIGHT ELEMENTS: 

BIRTH OF THE LIGHT ELEMENTS Big Bang Prediction: Fill Universe w/ lightest elements: Hydrogen, Helium, Lithium Example: 24% He Astronomical Observations: Measure light elements in near and distant sites At T = 1 billion degrees nuclear “ionization” stops nuclear reactions proceed rapidly 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

THE FUTURE: 

THE FUTURE

EXPANDING UNIVERSE: FINAL FATE: 

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

BBN AND DARK MATTER: 

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?

ORIGIN OF DARK MATTER:THE VERY EARLY UNIVERSE?: 

ORIGIN OF DARK MATTER: THE VERY EARLY UNIVERSE? Maybe Dark Matter = particles created at times << 1 sec !? T, energies ultrahigh Q: how probe such high energies? Hint: it’s in the Great State of Illinois Fermilab

INNER SPACE / OUTER SPACE: 

INNER SPACE / OUTER SPACE Fermilab is a telescope! Probes conditions in Universe at 10-12 s …but also… “The Universe is the poor man’s accelerator” Probes conditions inaccesible at laboratories Russian cosmologist Yakov Zel’dovich

OUTLOOK: 

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!

How Can I Learn More? Take Astrophysics!: 

How Can I Learn More? Take Astrophysics! ASTR 210 General Astronomy ASTR 290 Independent Study ASTR 304 Astrophysics ASTR 305 The Solar System ASTR 306 Galaxies and the Universe ASTR 314 Observational Astronomy ASTR 496 Research Seminars

As a Physics Major,the Astronomy Majorcomes at a discount!: 

As a Physics Major, the Astronomy Major comes at a discount! How can I join the fun? Two Words: Astronomy Major!

Slide35: 

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! From the Home Office in Urbana, IL... Top Ten Reasons to Major in Astro