1. Cosmology & Life
(Power Point 17)
NASA

2. Student Learning Objectives
Inventory the observable universe and analyze its formation, evolution and ultimate fate.
Asses the probability of intelligent life elsewhere in the universe.
Describe the Big Bang theory
List the Universe Timeline & Timeline for Life
Analyze possible fates of our universe
Describe how probability of life is determined

3. http://www. space. com/25804-big-bang-cosmology-discoveries-next-steps
Video by space.com

4. Cosmology is the study of how the universe has and is evolving.
What is cosmology?
Cosmology is the study of how the universe has and is evolving.
How "big" is the Universe, does it have an "end"?
What is its large-scale structure?
How old is the Universe, how long will it continue?

5. Age of Observable Universe
Oldest objects indicate Billion years
Expansion rate indicates 13.8 Billion years
Animation by EposChronicles
Image Credit: cornell.edu

6. How did the universe begin?
Central to every theory in modern cosmology is the observation that the universe is expanding.
Big Bang Theory
Start of space & time
Universe began to exist
Beginning of expansion

7. Video narrated by Janna Levin
Video narrated by Janna Levin

8. Practice How big is the entire universe?
Where is the starting point for the Big Bang?
The Big Bang is often thought of as an explosion. Was it an explosion? Explain.

9. Universe Timeline
Big Bang Event Energy becomes Matter H fusion to He Galaxies & Globular Clusters Form Space Expansion & Cooling Second Generation Stars Born E X P A N S I O

10. Universe Evolution
Early galaxies merged Superclusters formed filaments Giant voids appeared Expansion accelerating
Animation by SpaceSciNewsroom

11. Practice
Hydrogen fusion started in the universe (not in stars) soon after the Big Bang. What does this indicate about the conditions in space at that time?
Explain why are globular clusters more common in the past.
Explain what we see now, what types of objects exist, as a result of early galaxy mergers.

12. Space
Space itself is still expanding, however, localized gravity wells are maintained. (Galaxy clusters)
The overall structure throughout the universe is uniform. (Cosmological Principle)
Temperature is not the same everywhere in the universe. (Anisotropic)

13. Cosmic Microwave Background
As the universe expands, photon wavelengths are stretched, so energy and temperature are decreased. (Cosmological Redshift)
Microwave radiation is present throughout the universe.
Space has a temperature.
Average 3 Kelvin
long l = low E = low T

14. ESA
The anisotropies of the Cosmic Microwave Background (CMB) as observed by Planck Shows tiny temperature fluctuations

15. Practice
Why is the cosmic microwave background important in cosmology?
Are microwaves relatively high or low energy electromagnetic radiation?
Is the temperature the same everywhere in space? What could explain this?

16. What are the possible fates for our universe?
The critical density of the universe will determine whether matter or energy will win.
Critical density is the average density of matter, mass per volume of space, required for the Universe to halt its expansion after infinite time.
More matter, gravity wins (closed universe)
More energy, motion wins (open universe)
Mass per Energy → Fate

17. Density of Matter
in Universe
Fate
Less than
Critical Density
Expand Forever
Greater than
Collapse & Rebound

18. Practice
If the universe expands forever, what will eventually happen to all stars?
What does science show is dominating our Universe, matter or energy?

19. Dark Matter vs. Dark Energy
If we know the total density of all matter, we know the fate of our universe.
Dark Matter
Since space is expanding at an accelerated rate, something is working against dark matter.
Dark Energy

20. Dark Energy
 "NASA results confirm that dark energy (represented by purple grid) is a smooth, uniform force that now dominates over the effects of gravity (green grid).” NASA/JPL-Caltech

21. Dark Energy & Our Universe
It is indicated that the universe is mostly energy, by the expansion rate acceleration of our Universe.
68%+
Dark
Energy
27%
Matter 5%
“Normal”

22. What is dark energy?
Einstein postulated that empty space can possess its own energy.
Anti-Gravity Force
Property of space itself
Grows as space grows
Accelerates expansion
Albert Einstein was the first person to recognize that empty space is not nothing.

23. Space Fluid
A 2nd theory states that an energy fluid or field fills all of space.
Effects all of space
Increasing exponentially
Accelerates expansion
Quintessence

24. “Rip”
“Chill”
“Crunch”
Image Credit: Physics.org

25. Current Findings
The density of all matter in universe is equal to critical density.
Dark energy plays a significant role in the evolution of our universe, and it is “winning”.

26. Or we have gravity wrong
The Fate
The universe will expand forever.
Expansion will continue at an exponentially accelerated rate. "Rip“
Or we have gravity wrong

27. Questions to Ponder
If the universe is expanding and is expanding at an accelerated rate, how can we know the distance light has traveled?
How can we know the age of the universe?
How old is the universe really?
What lies beyond our “observable” universe?

28. Life on Earth requires carbon and water.
What defines life?
The primary condition that distinguishes living from non-living is DNA.
Chemical recipe for life
Can be copied (information passed to next generation)
May mutate to adapt to an environment
Life on Earth requires carbon and water.

29. Unlinked DNA under an electron microscope
Fidelity Systems

30. Origin of Organic Molecules
Reproducing molecules may have arrived here from space.
Outer Space
Hypothesis
Earth’s early oceans had organic compounds (carbon compounds) that developed into complex organic compounds.
Primordial Soup
Hypothesis

31. Timeline for Life
Life began in ocean (indicated by fossils) Oldest Simple Organisms Appear 3.4 billion years ago Complex Organisms Appear 540 million years ago Humanoid Species Appears 4 million years ago

32. Practice
How many years after the formation of Earth do the first signs of life appear?
Does the appearance of humanoids occur relatively early or late in Earth’s history? What does this indicate regarding the types of stars which could have life supporting planets?
Are there any projects looking for life elsewhere?

33. Nc = (N*)(fP)(nHZ)(fL)(fI)(fS)
Probability of Life
The probability of life can be calculated with a statistics based equation called the Drake equation.
Nc = (N*)(fP)(nHZ)(fL)(fI)(fS)

34. Probability VariablesN*
Number of stars in our galaxy fP
Fraction of stars that may have planets
nHZ
Number of planets that may be in the habitable zone fL
Fraction of HZ planets that may be suitable for life fI
Fraction of fL planets where intelligent life may evolve fS
Fraction of a star’s life available during which intelligent life may utilize communication

35. Practice
Based on your knowledge from this course, estimate a number for each variable in the Drake equation. N*
Number of stars in our galaxy fP
Fraction of stars that may have planets
nHZ
Number of planets that may be in the habitable zone fL
Fraction of HZ planets that may be suitable for life fI
Fraction of fL planets where intelligent life may evolve fS
Fraction of a star’s life available during which intelligent life may utilize communication