Exam 1 Flashcards
Memorize by 2/25 (100 cards)
Can science prove anything? Explain.
No, because we cannot confirm that the pattern will always repeat itself the same way. Instead, scientific data either supports or rejects our hypotheses
What does a scientific hypothesis have to be?
They must be falsifiable, meaning they can be supported or rejected using data but never proven. A hypothesis that isn’t falsifiable or testable is merely speculative
What is the difference between a law and a theory? Which is more strongly supported?
Theories aim to provide explanations for observations (essentially to provide the “why”). Laws aim to provide descriptions of observed phenomenon (provide the “how”).
Both are EQUALLY supported by data and scientific tests
What is considered “not science”? Why? What violates scientific method?
Things aren’t scientific if they don’t adhere to the scientific method or peer review process. This doesn’t necessarily mean they’re wrong or unimportant, they’re just not science.
Things violate the scientific method if they don’t rely on repeated observation, can’t be tested (non-falsifiable hypotheses), and/or don’t accept falsification
Construct a hypothesis and null hypothesis
If I turn the key in the ignition, the car will start
If I turn the key in the ignition, nothing will happen
If I smack my head into this wall, it will hurt me.
If I smack my head into this wall, I won’t feel it.
How old is the universe and how do we know?
About 14 billion years old
The furthest light that we’ve observed in the universe is just under 14 billion lightyears away
How old is the Earth and how do we know?
About 4.6 billion years old
We know this based on geometric dating of the oldest rocks/grains within rocks, as well as testing on meteorites
What is the evidence that supports the Big Bang Theory?
Observation of light waves in the universe as red-tinted (which, according to the Doppler effect, means they’re moving away)
Background cosmic radiation (the observable “echo” that resulted from the initial explosion)
How does the Doppler effect work?
If a wave is moving towards you, the wavelength will appear to compress/shorten, causing it to appear blue (shorter wavelength of light)
If a wave is moving away from you, the wavelength will stretch and shift toward red light
In the universe, almost everything has a red tint, meaning it’s moving away from us
How did the moon form and how do we know?
The moon formed when a large planetesimal hit Earth, causing debris to be ejected into orbit
Earth’s gravitational field captured this debris and eventually, it clumped together and formed a sphere due to gravity
We know this because:
- Earth is slightly titled
- The mantle is smaller than expected based on other planets
- The moon has the same rocks and chemical makeup as the Earth’s mantle
How and where are elements formed? What about heavy elements?
After the Big Bang, nucleosynthesis led to the formation of hydrogen and helium (the simplest elements)
As stars burn off these elements, they collide with one another and combine to form new elements (up until Iron)
Heavy metals are created when stars explode in supernovas because this event releases a lot of energy and increases the chances of atoms hitting each other to form elements heavier than Iron
What is the Iron Catastrophe?
Once the Earth got big enough, it began to differentiate into layers based on density, giving us the Iron dense core, the mantle, and the crust
As the core formed and spun, it created Earth’s magnetic field, allowing the ozone layer to form
Where does our water come from? Our atmosphere?
At this time, Earth was mainly lava and volcanoes. At these eruption sites, gas is released (along with molten rock of course)
These gases, such as hydrogen, accumulate and are trapped by the ozone layer to form the atmosphere
One such gas was water vapor and this became the main source of water for the oceans
How are the layers of the Earth defined? What does density have to do with this?
The core, mantle, and crust have different chemical compositions based on density (the most dense elements clump to the core/center, with the mantle being made of heavy silicates)
How do we know about the layers of the Earth?
Seismic waves tell us what the core is made out of because there are different travel times as they move through different mediums
What are the 2 types of crust?
How are they different?
Continental - less dense + mainly granite
Oceanic - denser b/c it’s made out of basalt (iron and magnesium)
What are some lines of evidence for plate tectonics?
What about for continental drift?
C.D. = continents seem to fit together like puzzle pieces, matching fossil records, matching landforms like mountains, glacial rocks, continuity of fault lines
P.T. = all of this + seafloor spreading
What are the 3 types of plate boundaries?
What features are associated with each?
1) Divergent (apart) = continental rifting and ocean basins (+ mild earthquakes)
2) Convergent (together) = major earthquakes, volcanoes, and mountain ranges
3) Transform (side-by-side) = moderate earthquakes
What are the 3 types of Convergent plate boundaries?
1) Continental - Continental = no subduction (similar densities) = mountains
2) Oceanic - Oceanic = subduction of older plate (b/c older = colder)
3) Oceanic - Continental = subduction of oceanic b/c denser materials
How did paleomagnetism help explain seafloor spreading?
Rocks preserve magnetization when they cool and solidify (dip below the “Curie temperature”)
This means that when magnetic reversals occur (switching of the m. north and south poles), this is reflected in the rock formations
This led to the creation of magnetic stripes along the ocean floor where magma is released and forms new rocks
How does density play a role in plate tectonics/subduction?
When plates collide, the denser one will be pushed beneath the other and sink back into the Earth’s interior at a subduction zone
What stage of the Wilson cycle is the Atlantic Ocean in? The Pacific?
Atlantic = younger (juvenile) b/c it’s growing
Pacific = older (elderly) b/c it’s shrinking
Are the Himalayas still growing? Why/How?
Yes, because they are formed by a continental-continental convergent boundary, in which two plates of very similar densities collide and neither subducts
Can mountains form along Oceanic-Continental plate boundaries?
Yes, but they’re much smaller than C-C
Ex: the Andes
