Welcome Back

Weekly Schedule

Today

•First HW Problems assigned

• Ch 28

• Review Q’s 1-5

• RAT- 1-4

•The Big Bang

•Stars and the formation

of elements

•Lab # 1: Intro to

Science

Next Tuesday

• Quiz # 1

• Elements, bonds, and

earth materials

• Crystallization activity

Remember Dark Matter? Yesterday were able to

Alpha Magnetic Spectrometer have shown hints of what is theorized to be dark matter.

Dark matter, which is believed to hold the universe together, has never before been

directly observed.

Few Quick Definitions

• Theory- well-substantiated explanation of some aspect of the natural world, based on a body of knowledge that has been repeatedly tested and confirmed through observation and experimentation (Plate tectonics and Big Bang)

• Scientific Law is a description of an observed phenomenon (Gravity and Hubble’s)

Formation of the solar system The Big Bang

Video

• Theory—our universe began with a

primordial explosion some 13.7 billion years

ago

• Marks the beginning of space and time

Big Bang • An expanding

Universe? “When

did it all begin?”

– The Big Bang: all

mass and energy

in a single point

– It exploded ~13.7

Ga and has been

expanding ever

since.

Fig. 1.5b

Aftermath of the Big Bang • Researchers have developed a model of the

Big Bang. – During the first instant, only energy—no matter—was

present.

– Started as a rapid cascade of events.

• Hydrogen atoms within a few seconds

• At 3 minutes, hydrogen atoms fused to form helium

atoms.

• Light nuclei (atomic no. < 5) by Big Bang nucleosynthesis

– The Universe expanded and cooled.

Fig. 1.5b

After the Big Bang • With expansion and

cooling, atoms began to

bond.

– Hydrogen formed H2

molecules—the fuel of

stars.

– Atoms and molecules

coalesced into

gaseous nebulae.

• Gravity caused collapse

of gaseous nebulae.

• Collapse resulted in

increases in:

• Temperature.

• Density.

• Rate of rotation.

Evidence of The Big Bang • Continuing expansion of the universe

• Measured cosmic background radiation

• Measurements of element abundances

The Big Bang Cosmic Microwave Background (CMB):

• The figure below shows the temperature of the CMB at every point in space. The uniformity of the CMB means that at some point in time all the matter in the universe was very close together.

The Big Bang

Relative Abundance of Light Elements

• Scientists predict that if the Big Bang occurred, there would not have been enough time to form any heavy elements due to the rapidly expanding universe; only hydrogen and helium could have been formed.

• 75% of all the matter in the universe is hydrogen and about 25% is helium. (Heavy elements make up less than 1%)

Close-up of the Eagle Nebula.

• Masses of hot and cold gasses colliding

• It is at the

Interface between the different temp gasses that protostars are formed

Aftermath of the Big Bang Forming Stars

Gravity Pushes inward

Nuclear Fusion pushes

outward. H + H He + energy

Protostars eventually heat up to initiate fusion

The future of a star is almost solely determined

by its MASS 25

15 3 1.5 1.0 .75 .50

35,00030,00011,0007,000 6,000 5,000 4,000

80,000 10,000 60 5 1.0 0.5 0.03

3 15 500 3,000 10,000 15,000 200,000

Size Surface Luminosity Lifetime Msolar Temp (K) Lsolar MegaYears

Lifetime of a Star

Mass of a star determines element production

• Small mass stars (Sun)

– Produce up to C

• Large mass stars (10-100x sun)

– Produce up to Fe and may…..

Supernova

Gravity wins over fusion= collapsing core which causes

violent expulsion of the outer layers of the star

SN 1987A

Supernova get hot enough to produce all elements heavier than Fe

U is the heaviest natural element

What’s left? Dust clouds= Nebula

The Crab Nebula was created from a supernova in 1054AD. Recorded in China. But not in Europe.

Forming the solar system ~4.5 Ga

• Formation of accretion disk

– Collapsing nebula’s gas flattens out because of gravity and conservation of angular momentum

Forming the solar system • In the center of the nebula compression begins

fusion of hydrogen into helium= SUN

• Electrostatic and gravitational interactions cause the dust and ice grains in the disk to accrete into Planetesimals

Forming the Earth • Accretion continues until

the center is hot enough to melt the rock= magma

• Earth forms and begins to differentiate via density

Forming the Moon~ 4.53 ± .01 Ga

• Crater the size of Mars

• Melted the Earth and ejected a large part of the mantle into space

• Eventually accreted into the moon

Forming the Atmosphere

• Three step process-

– Volatile gases during cooling

– Sulfur and CO2 from volcanic eruptions

– Bacteria began to produce oxygen about 2.8 G

• and Oceans

Forming the Oceans

• Earth cooled down, clouds formed and it rained

Forming the Solar System

Synopsis

The Earth System

Hydropshere Geosphere

Atmosphere Biosphere

Death of the Universe

• http://www.youtube.com/watch?v=lhTSfOZUNLo