Topic 02B: The Nature of Science and Oceanography, Part II. Online Lecture: Origins

Transcription

1 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.

2 Being 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 2B_2 Slide 2 e.g., someone who cannot see that their boy/girlfriend is cheating on them 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.

3 Being Scientific II 2B_2 Slide 3 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. Can you trust anyone who won t tell you why they believe what they do OR let you see evidence? Something can be true, even if it cannot be demonstrated by science (by observations). Drug companies only publishing results ( obs. ) that make their drugs look good. e.g., doctor, mechanic

4 Science: A Human Activity 2B_2 Slide 4 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 Before you turn in a paper for a class, what should you do? 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.

5 Science and Religion 2B_2 Slide 5 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) 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. Origins of Science: A belief in a world that we can understand, because it is a good world created by a rational God.

6 Stars make large atoms ( fusion ) 2B_2 Slide 6 H & He were created by the Big Bang. Make-up most of the universe H, C, O, N E = mc 2

7 Stars explode in Supernovae, creating dusty clouds called Nebulae 2B_2 Slide 7 Planetary Nebulae Supernovae Remnants Nebulae Clouds contain water, organic molecules, etc.

8 How do we know what stars and nebulae are made of? Spectroscopy 2B_2 Slide 8 Every substance has a light fingerprint: it absorbs and emits certain specific shades of each color Discovery of Helium

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

10 Age of the Earth: Radiometric Dating 2B_2 Slide 10 Moon Meteor Crater Age of the Earth: 4.5 billion years old

11 Water in Our Solar System Telescopes show us that water is quite common in the universe Saturn s Rings 2B_2 Slide 11 Asteroid Mars Poles Europa Comets Where else is water found in our solar system? How is water on Earth different from water elsewhere?

12 Where Did the Water in the Oceans Come From? Volcanoes 2B_2 Slide 12 Comets Which hypothesis seems more likely based on the observations that we have?

13 Why is the Ocean Salty? 2B_2 Slide 13 Rivers add salts add some salts, remove other salts Don t rivers carry fresh water? How can they make the ocean saltier?! Organisms Bodies Become Sediments remove salts Hydrothermal Vents balance between salt added & removed

14 The Fossil Record 2B_2 Slide 14 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?

15 Fossils in Sedimentary Rocks 2B_2 Slide 15

16 Specific layers of the rocks The Fossil Record II contain specific fossils Younger Layer Layers in different places "match." 2B_2 Slide 16 Cliff from Place #1 Cliff from Place #2 Youngest Layer Oldest Layer Older rock is on the bottom Older Layer

17 Early Life All lived in the ocean! 2B_2 Slide 17 Fossilized Cyanobacteria Tiktaalik Eurypterid Trilobite Why did life start in the ocean? advantages? disadvantages of living on land? Ammonites

18 Earliest Life: Bacteria eventually, Life created the Oxygen-Rich Atmosphere and the Ozone Layer Stromatolites 2B_2 Slide 18 Fossils of Stromatolites Oldest Fossils: 3.5 billion years old

19 The History of Life on the Earth 2B_2 Slide 19 First Appearance in the Rocks Winged Insects, Reptiles Seed plants, amphibians 1 st Life on Land Shelled organisms Multi-cellular Organisms Single-Celled Organisms Age of Rocks 300 million years ago 350 million years ago 440 million years ago 540 million years ago 2.3 billion years ago 3.5+ billion years ago For a more complete timeline, see Fig on p. 33 Order inferred from layers in sedimentary rocks. Time based on radiometric dating (which also confirmed the order).