An Astrobiology Review

The Physics and Chemistry of the Origins of Life in the Cosmos and on EarthHonors 228-003with Prof. Geller

What I’ll talk about

Some PhysicsOrigin of the UniverseSome Stars

and the elements they produceSome ChemistryOrigin of the Solar SystemPre-biotic origins of lifeSearch for LifeLife in Space

Kirchoff’s Spectroscopic Laws

Kirchoff’s Spectral Laws Continuous Spectrum

any body (ideal blackbody) that is at a temperature above 0 K

Emission Spectrumany low pressure gas that you

place a high voltage across

Absorption Spectrumany low pressure gas placed

between a blackbody and the observer

Bohr’s Atom

Best described the workings of the Hydrogen atom one proton and one electron “around”

the proton moving in orbits that are discretized (quantized) so that no intermediate orbits are allowed

Absorption Emission

Planck’s Radiation Curves

A way to depict frequency (inverse of wavelength) versus intensity

Frequency

Intensity

Wien’s Law

Peak wavelength is inversely proportional to the temperature of the blackbody

Intensity

Frequency

Cooler Body

Hotter Body

Peak Wavelength

Stefan-Boltzmann Law

Energy radiated by blackbody is proportional to the temperature to the 4th power

•E = T4

Energy vs. Temperature

0

10000

20000

30000

40000

50000

60000

0 2 4 6 8 10 12 14 16

Temperature

Energ

y

Newton’s Laws of Motion and Gravity

Newton’s First Law of Motion body at rest tends to stay at rest and

body in uniform motion will stay in straight line uniform motion unless acted upon by an outside force

Newton’s Second Law of Motion the acceleration of a body is

proportional to the force being applied

•F = m a

Newton’s Laws of Motion and Gravity

Newton’s Third Law of Motion for every force there is an equal and

opposite force (action and reaction)Newton’s Law of Gravitational Attraction

force is proportional to masses and inversely proportional to the distance squared

–F = (G m M) / r2

Doppler Shift and Hubble’s Law

A change in measured frequency caused by the motion of the observer or the source

The further away a galaxy is, the greater its recessional velocity

Einstein, Relativity, Cosmology

Albert Einstein 1905 Special

RelativitySpeed of light –

maximum speed 1915 General

RelativityGravity and space

linked via the curvature of space

Cosmologies Open, closed flat Ever expanding

Laws of Thermodynamics

1st Law of Thermodynamics the internal energy of an isolated

system is constant2nd Law of Thermodynamics

any change in a system is accompanied by an increase in the total entropy of the system

The Gas Laws

Boyle’s Law if temperature is constant, a given volume

of gas is inversely proportional to the pressure

Charles’ Law if pressure is constant, the volume of a

given gas is proportional to the temperatureAvogadro’s Law

if temperature is constant, the volume of a given gas is proportional to the number of gas molecules

© Periodic Table of the Elements

Los Alamos National Laboratories

Generic Phase Diagram

Molecules

Atoms get hitched ionic bonds

oppositely charged ions

covalent bondsatoms sharing electrons

Hydrogen bonds

The Evidence for Big Bang

Evidence for a “Big Bang” expansion of the universe

galaxies receding from us• everywhere the same

remnants of the energy from the “Big Bang”a very hot body that has cooled

• 2.7 K cosmic background radiation

the primordial abundance of chemical elements

How hot - the cosmic background radiation would be close to 3 K

Cosmologic Timescale

Era Epochs Main Event Time after bang

The Vacuum Era Planck EpochInflationary Epoch

QuantumfluctuationInflation

<10-43 sec.<10-10 sec.

The Radiation Era Electroweak EpochStrong EpochDecoupling

Formation ofleptons, bosons,hydrogen, heliumand deuterium

10-10 sec.10-4 sec.1 sec. - 1 month

The Matter Era Galaxy EpochStellar Epoch

Galaxy formationStellar birth

1-2 billion years2-15 billion years

The DegenerateDark Era

Dead Star EpochBlack Hole Epoch

Death of starsBlack holesengulf?

20-100 billion yrs.100 billion - ????

Geologic Timescale

Stellar Evolution determined by Mass

100100 0.10.10.40.41.01.04.04.010104040Mass (MMass (MSunSun = 1) = 1)

White dwarfsWhite dwarfs

NsNsBlack holesBlack holes

Main sequence starsMain sequence stars

Heavy nuclei fusionHeavy nuclei fusion

SupernovaeSupernovae Planetary nebulaePlanetary nebulae

C detonationC detonation

Helium flashHelium flash

Supergiants GiantsSupergiants Giants

A Massive (~25 Msolar) Star

Planetary Summary

PlanetMass

(Earth=1)Density(g/ cm3)

MajorConstituents

MercuryVenusEarthMars

0.060.821.000.11

5.45.25.53.9

Rock, IronRock, IronRock, IronRock, Iron

JupiterSaturn

31895

1.30.7

H, HeH, He

UranusNeptune

1417

1.31.7

Ices, H, HeIces, H, He

Nebular Condensation Model

Most remnant heat from collapse retained near center

After sun ignites, remaining dust reaches an equilibrium temperature

Different densities of the planets are explained by condensation temperatures

Nebular dust temperature increases to center of nebula

Nebular Condensation Chemistry

Molecule Freezing Point Distance fromCenter

H2 10 K >100 AUH2O 273 K >10 AUCH4 35 K >35 AUNH3 190 K >8 AU

FeSO4 700 K >1 AUSiO4 1000 K >0.5 AU

Nebular Condensation Summary

Solid Particles collide, stick together, sink toward center Terrestrials -> rocky Jovians -> rocky core + ices + light gases

Coolest, most massive collect H and HeMore collisions -> heating and

differentiating of interiorRemnants flushed by solar windEvolution of atmospheres

Minerals

Minerals natural substances that have definite crystal

structure and chemical compositiongalena, zircon, quartz, sulfur, turquoise, gypsum

how to distinguishstreak test, acid test, hardness test

• streak test uses unglazed tile, yielding colored streak• acid test using hydrochloric acid, yielding gasses• hardness, from 1 (talc) to 10 diamond

Igneous Rocks

Igneous rocks are formed when molten rock material called magma, cools and solidifies large crystals, slowly cooled

granite, quartz

small crystals, rapidly cooledpumice, basalt, obsidian

Sedimentary Rocks

Sedimentary rocks are formed from layers of sediments that have been compressed under water for long periods of time gravel and pebbles -> conglomerate sand -> sandstone mud and clay -> shale organic sediments + others -> limestone

Metamorphic Rocks

Metamorphic rocks are formed at depths under earth’s surface in regions of great heat and pressure limestone -> marble shale -> slate sandstone -> quartzite bituminous coal -> anthracite granite -> gneiss

From Earthto Moon

Secondary Atmospheres

Oxygen by Life

Terrestrial Planet Interiors

Planets, Atmospheres and Escape Velocities

Earthquakes and Plate Tectonics

Earth’s Interior andHow We Know

Crustal Rumblings

The Origins of Life

What is life? already discussed with Taylor

Was life transported to Earth from elsewhere? panspermia

What clues do we have about the first lifeforms?

Prebiotic Earth conditions.

Panspermia?

The Chemistry of Life

Thermodynamic considerations.Energy sources.

Solar Chemical

Observational clues about pre-biotic Earth matter from asteroids and comets

Atmosphere and lithosphere sourcesChemical stability

What preceded nucleic acids?

Inorganic polymers simpler, more accessible

Examples of inorganic polymers clays and non-clay minerals

Clays might have a role in life evolving Clays are linked with covalent bonds

composed of cationic and anionic polymers metallic cations pickup hydrogen in water e.g. brucite (magnesium type polymer) and

gibbsite (aluminum type polymer) Clays and combinations of clays might have

evolved into living system prior to nucleic acid lifeforms

A Clay - Kaolinite

Other Minerals’ effects on the Evolution of Life

Pyrite (iron sulfide) has been known to act as a surface for reactions

Calcite has been shown to preferentially bond left and right organic molecules

Clays may act as “catalysts” by holding molecules in place and allow time for chemical bonding of more complex molecules

A MolecularScenario

Microspheres

Chemical Evolution Review

Looking for Life on Mars (the only experiments launched that were designed specifically to look for life)

The biology laboratory aboard Viking approximately a single cubic foot of

volume three experiments for searching for life:

pyrolytic release experimentlabeled release experimentgas exchange experiment

Explaining Biology Away

Theories dealing with superoxides, peroxides and superperoxides to explain apparent positive results away the results

Only hold-out for the possibility that the biology experiments still might indicate the existence of life on Mars was Gilbert Levin [only science team member that still maintains belief that evidence of life was found]

Meteorites from Mars (with fossils of life?)

ALH84001 possible

evidence of fossil microbes from Mars

How Far Can We Communicate?

Past Searches

Humans in Space

Gerard K O’Neil Space colony

cylinders

What happens after stars die?

The Degenerate Era “Dead stellar remnants capture dark

matter, collide with each other, scatter into space, and finally decay into nothingness.”

Brown dwarfs, white dwarfs, neutron stars, black holes

Galaxies in collision, galaxies in relaxation, degenerate stellar collisions, annihilation of dark matter

Proton decay and the growth of black holes

Do black holes inherit the wind?

The Black Hole Era “Black holes inherit the universe, warp

space and time, evaporate their mass energy, and make an explosive exit.”

Black holes, gravitational radiation Hawking radiation and the decay of

black holes Can life exist in black hole era?

When black holes evaporate?

The Dark Era “The nearly moribund universe

struggles with cosmological heat death and faces the possibility of universally transforming phase transitions.”

Radiation, heat death Annihilation and tunneling Phase transitions and re-birth?

Astrobiology in a Nutshell

Mnemonic – ODDS Origin Development Distribution Search

A universe of, for and by life

HAVE A GREAT SUMMER