2B_2 – Slide 1

Topic 02B:The Nature of Science

and Oceanography,Part II

Online Lecture:Origins

The Formation of Atoms, Molecules, the Earth, and the Oceans.

2B_2 – Slide 2Being Scientific I

○ If no matter what the evidence is, someone will not alter their belief (they always make excuses or “maybes”) then they are not treating the matter scientifically

○ How is scientific evidence different from non-scientific evidence? Why is the difference important?

Only observations are accepted by scientists as evidence, because they can be “checked” by anyone:– You can see for yourself. – You do not have to take anyone’s word for it.– You do not have to take anything on faith.

e.g., someone who cannot see that

their boy/girlfriend is cheating on them

2B_2 – Slide 3Being Scientific II

○ A scientific hypothesis or theory is an idea that can be “tested” by making observations.

○ A scientific theory must explain ALL of the evidence.

○ Being an “expert” means nothing. An “expert” is just someone who is familiar with all the evidence. Drug companies only

publishing results (“obs.”) that make their drugs look good.

e.g., doctor, mechanic

Something can be true, even if it cannot be demonstrated by science (by observations).

Can you trust anyone who won’t tell you why they believe what

they do OR let you see evidence?

2B_2 – Slide 4Science: A Human Activity

○ Suppose a scientist lies about his or her observations to get ahead in their career, for $, for fame,…whatever.

Why will they eventually be found out and discredited?

someone will try to repeat their results,and get different observations

○ What is Peer Review? Scientists check one another’s work before publishing

There is only so much $ for and space in science journals: Peer Review is the standard method that is used to determine whose work is better or more important and so should get published.

Before you turn ina paper for a class,

what should you do?

2B_2 – Slide 5Science and Religion

○ Can science answer all the questions that we care about?e.g., Is it ever OK to steal? How do I live a “good” life?

Who is the greatest basketball player?Which is more beautiful, a sunset or a baby’s smile?

○ Science and its observational evidence do not necessarily reject or disprove religion, but they do affect religion (e.g., how sacred texts are interpreted)

Origins of Science:A belief in a world that

we can understand, because it is a “good”

world created by a rational God.

People throughout the world experience (i.e., observe) and

interpret their experiences of the “divine” in radically different

ways, making it difficult to address religion scientifically.

2B_2 – Slide 6Stars make large atoms (“fusion”)

H & He were created by the “Big Bang.”

Make-up most of the universe

H, C, O, N E = mc2

2B_2 – Slide 7Stars explode in “Supernovae,”creating dusty clouds called “Nebulae”

Planetary Nebulae

Supernovae Remnants

Nebulae Clouds contain water, organic molecules, etc.

2B_2 – Slide 8How do we know what stars and nebulaeare made of? “Spectroscopy”

Every substance has a “light fingerprint:”it absorbs and emits

certain specific shades of each color

Discovery of Helium

2B_2 – Slide 9Formation of the Solar System & the Earth

Gravitational attraction pulls nebula together

“Conservation of Angular Momentum”forms it into a disc & causes the rotation.

Gravitational attraction pulls parts of the disc together

into Sun & planets

“Solar Wind” blow lighter materials away

from the center.

2B_2 – Slide 10Age of the Earth: Radiometric Dating

Moon

Crater

Meteor

Age of the Earth:4.5 billion years old

2B_2 – Slide 11Water in OurSolar System

Comets

Asteroid

Saturn’sRings

Mars’Poles Europa

Where else is water found in our solar system?How is water on Earth different from water elsewhere?

Telescopes show us that water is quite common in the universe

2B_2 – Slide 12Where Did the Water in the Oceans Come From?

Which hypothesis seems more likely based on the

observations that we have?

VolcanoesComets

2B_2 – Slide 13Why is the Ocean Salty?

Organisms’ BodiesBecome Sediments

Rivers

Hydrothermal Vents

add salts

remove salts

add some salts,remove other salts

“balance” between salt added & removed

Don’t rivers carry fresh water? How can they make the ocean saltier?!

2B_2 – Slide 14The Fossil Record

○ Fossils are the remains of living things:bones, impressions (tracks, skin, feathers), dung, etc…

○ An incomplete & imperfect record of life in the past,so one must be careful when interpreting the fossil record

– new discoveries are constantly filling in gaps

– remains of some organisms are preserved more easily than others

If we find more fossils of shelled animals than “jellies”, should we conclude that there were more shelled animals than “jellies?”

2B_2 – Slide 15Fossils in Sedimentary Rocks

2B_2 – Slide 16The Fossil Record II

Layers indifferentplaces

"match."Younger Layer Youngest Layer

Older LayerOldest Layer

Cliff from Place #1 Cliff from Place #2

Specific layers of the rocks contain specific fossils

Older rock is on the bottom

2B_2 – Slide 17Early Life

Tiktaalik

Trilobite

Fossilized Cyanobacteria

Ammonites

All lived in the ocean!

Why did life start in the ocean? advantages?

disadvantagesof living on land?

Eurypterid

2B_2 – Slide 18

Earliest Life: Bacteria – eventually, Life created the Oxygen-Rich Atmosphere and the Ozone Layer

Stromatolites

Fossils of Stromatolites

Oldest Fossils:3.5 billion years old

2B_2 – Slide 19The History of Life on the Earth

≈ 3.5+ billion years agoSingle-Celled Organisms

≈ 2.3 billion years agoMulti-cellular Organisms

≈ 540 million years agoShelled organisms

≈ 440 million years ago1st Life on Land

≈ 350 million years agoSeed plants, amphibians

≈ 300 million years agoWinged Insects, Reptiles

Age of RocksFirst Appearance in the Rocks

For a more complete timeline, see Fig. 1-20 on p. 33

Order inferred from layers in sedimentary rocks. Time based on radiometric dating

(which also confirmed the order).