Universal Future Name all four components of the Universe that lead to the name The Degenerate Era. 2. What are two energy sources during the Degenerate Era? 3. What causes the Milky Way’s demise in the Degenerate Era? 4. What is the primary energy source in the Black Hole Era? 5. Name three of the four waste products left in the Dark Era. B. How long do the stars last (the end of the Stelliferous Era)? White dwarfs dominate Degenerate Era.

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Universal Future Name all four components of the Universe that lead to the name The Degenerate Era. brown dwarfs, white dwarfs, neutron stars, black holes 2. What are two energy sources during the Degenerate Era? dark matter annihilation in white dwarfs proton decay in white dwarfs nuclear fusion in red dwarfs made in brown dwarf mergers 3. What causes the Milky Way’s demise in the Degenerate Era? encounters and collisions between objects … evaporation 4. What is the primary energy source in the Black Hole Era? Hawking radiation 5. Name three of the four waste products left in the Dark Era. photons, neutrinos, electrons, positrons B. How long do the stars last (the end of the Stelliferous Era)? 100 trillion years or cosmological decade 14 White dwarfs dominate Degenerate Era.

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? Future Universe

critical density ρc = 10-29 g/cm3 Future Universe Type depends on DENSITY of Universe DENSITY = mass / volume critical density ρc = 10-29 g/cm3 Options closed …… bound redshift becomes blueshift heat death open …… unbound redshift forever freeze death both mass and volume (distance) are tough to measure

Open or Closed?

Future Universe Options closed …… bound redshift becomes blueshift heat death open …… unbound redshift forever freeze death critical …… borderline reshift forever

Future Universe But … what about dark matter? what about dark energy? gravity is only force that matters on large scales? Test something bright very, very far away … Type I supernovae (white dwarfs going BOOM!) measure distance … compare redshift distance from standard candle and brightness … time ago redshift measures total expansion since that time >>> map of redshift vs time >>> Hubble’s Law not constant expect Universe is decelerating due to gravity expansion would be SLOWER now galaxies receding FASTER now

Accelerating Universe! expansion FASTER now WHAT ?!?!? dark energy opposes gravity largest scales only Observations of distant supernovae allow astronomers to measure changes in the rate of expansion of the universe. In a decelerating universe (purple and red curves), redshifts of distant objects are greater than would be predicted from Hubble's law (black curve). The reverse is true for an accelerating universe. The points showing observations of some 50 supernovae strongly suggest that the cosmic expansion is accelerating. The vertical scale shows redshift; for small velocities, redshift is just velocity divided by the speed of light. (More Precisely 24-1) (b) The bottom frames show three supernovae (marked by arrows) that exploded in distant galaxies when the Universe was nearly half its current age. The top frames are wider views of areas around these supernovae, which were originally discovered in 1997 during a ground-based survey with the Canada-France-Hawaii Telescope on Mauna Kea. (P. Garnavich/Harvard-Smithsonian Center for Astrophysics/NASA)

? Future Universe

Accelerating Universe ? Accelerating Universe closed flat open accelerating An accelerating universe can be closed, flat, or open depending on the strength of gravity relative to the repulsive force (and when you’re looking???). gravity + dark energy gravity only

Future Universe Options closed …… bound redshift becomes blueshift heat death open …… unbound redshift forever freeze death critical …… borderline reshift forever accelerating …… unbound redshift forever, and changing

Are Type I Candles Standard? But wait … Type I supernovae (SN) are SN the same at all times? SN appear to look bluer helium fraction or metallicities change at large z, only massive WDs have time to accrete mass to SN “standard” candles are not perfectly standard … WD composition is the redshifted spectrum of the SN leading to data analysis issues? could observational errors be the problem? SN peak brightnesses at z = 0.5 differ from coasting Universe by only 0.14 ± 0.06 to 0.06 ± 0.04 magnitudes must get good sampling to nail peak must correct for underlying galaxy emission must account for interstellar medium/reddening/dust issues must consider gravitational lensing of SN

Cosmic Conclusions BIG FREEZE AHEAD Conclusions 1. Big Bang origin 2. Universe’s age is 13.7 ± 0.2 Byr 3. CMB restricts matter/radiation densities, Universe’s age 4. inflation, when/how much large scale structure 5. 4% normal matter + 23% dark matter = 27% critical 6. dark energy exists, brings density up to CRITICAL BIG FREEZE AHEAD

Five Universal Eras Five Eras like geology (8 Epochs absorbed into first two Eras) PRIMORDIAL STELLIFEROUS DEGENERATE BLACK HOLE DARK … (and depressing)

Past and Now 1. PRIMORDIAL 10-50 to 105 years ENERGY …… Big Bang radiation dominated  microwave background matter over antimatter H, D, He, Li STARS START TO FORM AT 105 YEARS 2. STELLIFEROUS 106 to 1014 years (now = 1010) ENERGY …… nuclear burning in stars superclusters, clusters, galaxies, stars form quasars, AGN at early times red dwarfs last trillions of years NO MORE GAS TO MAKE STARS AT 1014 YEARS

The Future is Grim 3. DEGENERATE ERA 1015 to 1039 years normal mass in BDs, WDs, neutron stars, black holes galaxies modify structure … heavy to center ENERGY …… neutron  proton + electron + neutrino proton  positron + pion pion  photon + neutrino electron + positron  photon + neutrino ENERGY? …… dark matter into WDs (primarily) white dwarfs … 400 watts (black dwarfs) Milky Way as bright as 1 Sun NO MORE PROTON DECAY AT 1039 YEARS BD crash = new stars … WD crash = supernova

And It Gets Worse … 4. BLACK HOLE ERA 1040 to 10100 years only black holes remain (no proton decay) sweep up material and grow ENERGY …… black holes evaporate Hawking radiation pair production at event horizon BH with 1 Msun … 1065 years BH with 1 Milky Way … 1098 years NO MORE HAWKING RADIATION AT 10100 YEARS

The Bitter End … THERMODYNAMICS WINS OVER GRAVITY 5. DARK ERA > 10101 years electron + positron  positronium (real!) ENERGY …… when they annihilate each other  neutrinos + photons THERMODYNAMICS WINS OVER GRAVITY

Fade to Black …

End of Life on Earth Sun will last 6 Byr more … twice as bright as today red giant … HB star … AGB star … white dwarf … black dwarf winds during red giant phase … 25% mass loss Earth spirals out Earth heating makes oceans hold less CO2 and H2O CO2 in atmosphere causes runaway greenhouse effect oceans evaporate in 2 Byr no H2O … no life Escape? 1/100,000 odds Earth booted by passing red dwarf crosses (former) Pluto orbit in a few years continents ice over … then oceans freeze from top down at 77 K, N2 freezes out and rains onto ice oceans … O2 soon after life survives along hydrothermal vents powered by radioactive decay

Solution? LEAVE EARTH

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Cosmic Structure The most obvious features on the high-resolution map of the microwave background shown in Figure 27.17 occur on a scale of about 1°--the approximate size of the "blobs" in the inset to that figure. The graph shown here quantifies this impression by plotting the correlation (vertical axis) between different points on the map separated by a given angle (horizontal axis). In effect, the height of the graph measures the "amount" of structure seen on different angular scales. The blue curve is a theoretical prediction for a flat (Ω0 = 1) universe with the cosmological parameters quoted in the text. The excellent agreement between theory and observations is regarded by most cosmologists as strong evidence that we live in a flat, critical-density universe.