Astronomy

What are three types of renewable power sources mentioned in the film? Briefly explain two major drawbacks that are associated with renewable energy sources in general.

wind, solar, and biomass. One major drawback associated with renewable energy sources in general is that they are episodic. Another major drawback is that there is lower power density and it requires a large amount of land.

Briefly explain three things that can change the Earth's reflectivity, aside from melting ice or freezing water.

1. Smog particles act like volcanic dust and reflect the sunlight before it hits the ground 2. Deforestation increases reflectivity because it removes the plants that absorb sunlight 3. Roads and cities decrease reflectivity because there's nothing there to absorb light

List the three other major factors besides changes in the greenhouse effect that can cause climate change. Explain how and why a change in axial tilt of the Earth would change the climate to be warmer or cooler.

1. Solar brightening 2. Changes in axis tilt 3. Changes in reflectivity A change in axis tilt can affect the climate by making seasons more or less extreme. The greater the tilt, the more extreme the season. The hotter the summer prevents ice from building up, reducing the planet's reflectivity, and making it warmer. If the tilt is smaller then the seasons will be less extreme, allowing ice to build, and making the planet cooler.

Briefly describe each of the three properties of a planet that determine its temperature. Use these to help explain how we know that the greenhouse effect is real and warms the Earth by about 60 degrees Fahrenheit.

3 things that affect a planets temperature 1.Distance from the sun 2.Reflectivity 3. Atmosphere Anything that blocks infrared light is called a greenhouse object (glass,co2, etc.). CO2 acts as a greenhouse object for earth. We are about the same distance from the sun as the moon and have a similar atmosphere, yet our reflectivity is greater, so in theory we should be cooler or cool like the moon, yet our temperature is rising because of a rise in CO2 emissions in our atmosphere acting as a glass, blocking infrared light.

Describe how written records can be used to estimate the temperature from hundreds of years ago, even before the invention of the thermometer. How does the logical chain work to get from "this particular lake first froze over in March of this particular year" to use knowing what the temperature was during that particular year?

500 years ago there were written records of when lakes thawed, when trees bloomed, etc. Today we have the same records, but now we have temperature measurements (calibration). Now we can go back and extrapolate. It is an uncertain number, but it is a good estimate of the worldwide temperature.

Briefly explain the difference between a particle and a wave. Also, know the simple definitions of wavelength, frequency and photon.

A particle can sit still or move from one place to another like marbles or a baseball. Waves consist of peaks and troughs. A particle is a thing, while a wave is a pattern revealed by its interaction with particles. Wavelength: the distance from one peak to the next Frequency: number of peaks passing by any point each second Photons: individual pieces that make up lights that have properties of both particles and waves. A photon is characterized by a wavelength and frequency

Explain how we use deep-sea sediment cores to indicate temperatures long ago. Also, explain why these sediment cores are the most degraded and difficult to interpret during the period when the most warming took place?

As sediments are laid down they trap minerals-including fossils of sea life-that retain signatures of the composition of the surrounding oceans and atmosphere as well as life forms present at their time of decomposition. The mixes of isotopes of oxygen atoms in the fossils reveal the temperature of the water. When the cores are well preserved, they reveal climate history, but many of those that included the PETM weren't in good shape. Parts were missing and those left behind had been degraded by the passage of time. During the PETM, ocean acidification dissolved most of the carbonate in the sediments in exactly the layers where the most extreme conditions of the PETM era should have been represented.

Describe the negative feedback loops that have kept Earth's climate from becoming too warm or too cold in the past. Why are these feedback loops likely not sufficient to stabilize Earth's climate if we triple the Carbon abundance in our atmosphere over the course of the next 100 years?

As the temperature warms, there is more evaporation and rainfall, pulling more CO2 out of the atmosphere cooling the planet down. As the temperature cools, precipitation decreases and less CO2 is dissolved allowing CO2 to be released by volcanism strengthening the greenhouse effect, thus heating the Earth. If we triple CO2 and greenhouse gases then we will see changes in global climate over a much shorter amount of time. The CO2 cycle operates too slowly to absorb these emissions on a human scale, so global warming will occur. Either way, in 3-4 billion years, the Sun will be so warm that the sunlight on Earth will be as intense as it is on Venus. Our planet will become a Venus-like hothouse and the temperature will be far too high for liquid water to exist.

Explain the two chemical changes that occurred in the oceans due to the PETM warming. What were these changes, and how did rising CO2 levels cause them?

At first, absorbing all the CO2 offset the warming, but eventually, it seeped into the deep ocean and created a surplus of carbonic acid. As the deep sea warmed, the oxygen content dwindled because warmer water can't hold as much oxygen as cold can. These two changes caused disaster for microscopic organisms that lived on the seafloor and eventually 50% went extinct.

Describe the carbon cycle

Atmospheric carbon dioxide dissolves in rain water creating acid, the rainfall erodes rocks and rivers carry the minerals to the oceans. In the oceans, calcium from the minerals combines with carbon dioxide and falls to the ocean floor creating limestone. Over millions of years, plate tectonics carry the rocks to subduction zones and they are carried down. As they are pushed deeper some of the sub ducted rocks melt and release carbon dioxide back in the atmosphere through volcanoes.

What are breeder reactors? How might breeder reactors overcome one of these drawbacks, and what is a major problem associated with breeder reactors?

Breeder reactors take neutrons from decaying and bombard uranium. They then turn it to Plutonium to create another fuel rod to extend the lifetime of Ur. It can create meltdowns more and it requires more control. Also, the countries that are known to have breeder reactors are bound by a non-proliferation treaty which means they can't share the knowledge they have to anyone else, so not only are breeder reactors unstable, they are extremely hard to come by since the countries that have the technology aren't sharing it.

If the Kyoto protocol were enacted, how would that change projected atmospheric concentrations of carbon dioxide over the next 100 years, compared to "business as usual" projections?

Currently the Co2 levels are at 400ppm. At the beginning of the industrial revolution it was 260 and at the end it was 700 ppm. If all countries participate in the Kyoto protocol then we'd reach 660 ppm, a 90% increase.

Explain how we can use ice core measurements to estimate the Carbon Dioxide content of the atmosphere hundreds of thousands of years ago. How do current atmospheric conditions compare to those measured during the past 400,000 years?

Data is found in ice bubbles in the ice cores. These ice bubbles show the amount of CO2 in the air at that time. Scientists also find micro organisms thriving in the ice to determine temperature since different bacteria thrive in different temperatures. There has been a significant increase in CO2 from 340million per part in the 1950s to the upper 400 today.

What are Deuterium and Tritium? Explain how nuclear fusion (D-T fusion) generates dangerous waste products.

Deuterium is an isotope of Hydrogen with a proton and a neutron in its nucleus. Tritium is an isotope of Hydrogen with a proton and two neutrons in its nucleus and is unstable. Combining the two creates the easiest fusion reaction, but it generates waste because as an unstable neutron comes off, it can't be contained and it turns the container into something radioactive.

Briefly describe the four different ways that light can interact with matter.

Emission: emit visible light (light bulb)-light comes from an electrical potential energy Absorption: absorbing light (putting your hand over an incandescent light bulb) Transmission: Allowing light to pass through Reflection/Scattering: Light can bounce off matter. When it bounces off in the same direction it is reflection. When it bounces off random it's scattering.

Briefly explain why climate scientists weren't satisfied with the Kyoto treaty and also why politicians were also not satisfied (summarize one of the reasons given in each case).

Even if Co2 increases by 90%, there is still a cone of uncertainty. Politicians say it isn't good for a variety of reasons. Climate change hasn't been proven. There's an unfairness to developing worlds. They say the didn't do anything to contribute to the Co2 emissions, so why should they make change.

Explain how water can be used to store energy generated by windmills for later use when the wind isn't blowing.

Excess electricity is used to pump water from a low reservoir to one higher uphill. When the water falls back to the lower reservoir it passes through a turbine that turns a generator to create electricity.

Explain why nuclear fusion reactions require extremely high temperatures. Also, why must the fusing material be contained somehow and a high density maintained?

If nuclei are moving fast enough then strong force will override the electric forces and lock them together. In order for them to move fast enough, extreme heat is required. The fusing material must contained so that it confines gas to make collisions. Collisions need to be common and head on, so they have to be confined in a high-density material that can handle the extreme heat.

In computer models, name and explain one example of a positive feedback effect and a negative feedback effect. Why do the computer models have such a wide range of possible predictions about future temperatures?

If you just deal with greenhouse gasses it doesn't make much a difference. Positive feedback means the effect positively amplifies the original cause. An example for positive feedback is that the ice gets warmer, surface absorbs energy, and the earth gets hotter. Negative feedback means the effect negates the original cause. An example of negative feedback is that the earth gets warmer, ice evaporates, low, thick clouds form, cooling the earth. When you look at both of these it creates a field of uncertainty. The problem is, we don't know what's going to happen. When scientists look at temperature change over time, there's a cone of uncertainty.

Use the barrel of apples analogy to help explain the difference between "probably true" and "almost definitely true, beyond any reasonable doubt."

It is important to get a clear sample from multiple views. For instance, if you pulled some apples from the top and they aren't rotten, it doesn't mean that the ones are the bottom aren't rotten. More samples need to be drawn to get an accurate reading. Even if you think 99 apples will be rotten and you pull out 49 rotten apples, how will you accurately know the remaining will be rotten? If the hypothesis is that all the apples in the barrel are rotten, then the ones in the middle should be rotten. However, the entire method is based on induction. If the apples in the middle of the barrel are rotten it confirms the hypothesis, but doesn't logically prove it. You have to fully test out your hypothesis in order to prove it. For example, if you want to prove that 99 apples are rotten, you have to pull out at least 99 apples.

Why is it difficult to contain fusion reactions? Explain inertial and magnetic confinement.

It's difficult to contain fusion reactions because the temperature is so high that everything melts into plasma. In inertial confinement, the D-T mixture is made into a solid pellet. The pellet is placed in the center of a device that fires laser beams into the pellet from all directions. In magnetic confinement, a tokamak generates a magnetic field in a continuous ring and confines the plasma inside the ring as it's heated.

From the reading "Cargo Cult Science", briefly explain the story of the Millikan oil drop experiment and the subsequent history. Explain why this was such an embarrassing episode for scientists.

Millikan measured the charge on an electron with falling oil drops and got the wrong answer because he had the wrong viscosity for air. The years after Millikan, people began to find a larger number for the viscosity of air. People didn't realize it was higher right away because they thought that Millikan's number was right, so theirs had to be wrong and they would look for reasons why something could be wrong. They would eliminate numbers that were too far off from Millikan's number and didn't question his findings. However, this shows a lack of scientific integrity.

From the reading "Cargo Cult Science", briefly summarize the story of Mr. Young's experiment and why those who ignore his work cannot really trust their conclusions.

Mr. Young did an experiment to test how rats knew where food was. He built a corridor with two ends. Doors were on one end and food and more doors were on another end. He put the rats into the corridor with no food. He tried to get the rats to go out another door with no food in front of it, but they chose the doors with food every time. To try to mix things up for the rats he painted all the doors different colors, but still they knew were the food was. He thought they were smelling the food, so he put in a chemical to mask the smell, then he covered the lights, but the rats could still tell where the food was. He figured out that the way rats could tell was by the way their feet sounded on the floor, so he put the corridor in sand and was able to fool the rats. The researchers subsequent of his work never referred to his work because Mr. Young never discovered anything about the rats, only how to control them. He discovered everything you need to know to learn about rats. Everyone that ignored his work is conducting research with rats wrong because they aren't using fundamental information of what needs to be done to control experiments with rats.

To go back further, 1000 or more years, scientists look in places like Lake Tuborg or an old forest. Briefly describe what scientists look for when they look at ice layers in a frozen lake and tree rings in a forest. Do thicker layers/tree rings mean warmer (wetter) climate or cooler (drier) climate? Explain why for each case.

Natural climate recorders are more reliable. An example of a natural recorder is sediment taken from the lake. Scientists look at sediment.The longer the lake is thawed, the thicker the sediment. The thicker the sediment, the warmer the temperature, the thinner the sediment the cooler the temperature. The same thing goes for tree rings. The thicker the ring, the warmer the temperature. As temperature warms, the weather is wetter, and trees grow. Scientists can go back and see these natural indicators of temperature.

Will this "greening hypothesis" enable the problem to essentially solve itself by taking all the excess Carbon out of the atmosphere? Explain.

No it won't, because when the trees and plants that sequestered the CO2 will die and decay and put the CO2 back in the air

Explain how nuclear fission generates energy (where, exactly, does the energy come from in the reaction). Also, explain briefly how nuclear power plants convert this energy into electricity.

Nuclear fission generates energy by splitting the atoms of uranium. U-235 splits causing a chain reaction to where it produces a lot of heat and the atom's loses some of its mass. The heat boils the water to steam which moves the turbine to generate an alternating current producing electricity.

Explain how underground caverns can store and release energy generated by windmills. Also, explain one technical hurdle in this process and how utilities are trying to overcome it.

On the surface, powerful electric pumps inject air at high pressure into the cavern. When the grid is running short, some of that compressed air is let out, blasting through turbines and spinning them. One hurdle is that air heats up when it is compressed and gets cold when it is allowed to expand. That means some of the energy that goes into compression is lost. And if the air is let out, it can get so cold that it freezes everything it touches. They are trying to overcome it by choosing containers that can handle high density and pressure. Also, the heat loss is made up for by heating the high pressure air using natural gas fuel

One alternative source of power that may help account for current energy production and future growth is nuclear energy. What are two major long-term drawbacks associated with nuclear energy?

One major long term drawback with nuclear energy is uranium is very rare. There's not enough in the ground to last forever and for everyone to have. The second drawback is nuclear waste. We don't know how to dispose of nuclear waste so it's isolated from its environment. We don't want to dump it into our oceans or bury it in land because then people could be poisoned as well as our ecosystem.

Summarize in a sentence or two another mechanism besides melting ice that may cause sea levels to rise as the Earth warms up.

One other incident other than melting ice that may cause the sea levels to rise is the warming/cooling of the ocean. Cold water is more dense, so it occupies the same amount of space with the same mass of water. When water is warmed, a small, but nonzero expansion occurs. But the problem is that the water is only heated from the top so the cold water sinks. However, the ocean mixes and over time the warm water would mix with the cold water and eventually, after a long time, cause a rise in the sea level.

Explain two lines of argument that support the idea that the increase in Carbon Dioxide in Earth's atmosphere over the past 200 years is largely due to human activity as opposed to a natural process or cycle.

Our atmosphere is 99% C-12 and 1% C-14 (half-life 600 years which means it replenishes as fast as it goes). Fossils are dead for millions of years and are 100% C-12. Plant decay, organic decay, and volcanism are all natural resources with a heavier carbon fingerprint. Yet, over 200 years C-12 has gone up 50% and C-14 has increased at 0%.

Describe plasma and explain why matter normally takes on this form at very high temperatures (this will be important for our discussion of nuclear fusion later)

Plasma is a type of hot gas, which atoms have become ionized. This gas consist of freely moving electrons and positively charged ions of hydrogen and oxygen. High temperature creates collisions and a more energetic light which separates the electrons.

What is a Q-value, and how does it relate to the viability of nuclear fusion as an energy source?

Q-value is the efficiency of the reactions. It's expressed as the output of energy divided by the input. You have to have a Q-value greater than 20 in a lab in order for reactors to be commercially viable, so that it reaches a Q-value of 1 or 2 when commercialized.

What is radiative forcing? What does "positive" radiative forcing and "negative" radiative forcing mean? Give an example of each in climate science.

Radiative forcing is the change that is caused in the global energy balance of the earth today compared to preindustrial times. A positive forcing causes warming and a negative forcing causes cooling. An example of positive forcing is greenhouse gases trapping in CO2. An example of negative forcing is clouds and aerosols reflecting solar radiation.

What evidence in our atmosphere suggests that the recent warming of the past century is not due to changes in solar activity?

Solar radiation has been on a downward trend in the past four decades, while Earth's temperatures have been rising. We started seeing noticeable increases in greenhouse emissions after 1950, after fossil fuels were introduced. Solar radiation is a tiny percentage compared to human made emissions

Explain how infrared light compares to visible light in the electromagnetic spectrum. Specifically, is it longer or shorter wavelength? Higher or lower frequency? Higher or lower energy?

That light that we can see is called visible light. It's in near the middle of the spectrum with wavelengths ranging from about 400 nanometers at the blue/violet end to about 700 nanometers at the red end. Light with longer wavelengths than red light is called infrared because it lies beyond the red end of the rainbow. Longer wavelength, lower frequency, and lower energy.

Explain the evidence offered by the textbook's authors (related to computer models) that suggest the recent warming of the Earth has been caused by human activity rather than some natural cycle.

The Earth's average surface temperature has risen during the last several decades. Climate models that only use solar and volcanic changes fail to match the rise in temperature. Whereas those that include the human greenhouse gases explains the warming.

Explain how the Kelvin temperature scale is related to Fahrenheit and Celsius. What is absolute zero? One advantage of the Kelvin scale is that it never uses negative temperatures. Explain why this makes sense using the definition of temperature.

The Kelvin scale doesn't have negative temperatures. The scale starts at absolute zero-the coldest possible temperature. The Kelvin scale is related to the Celsius scale. The difference between the freezing and boiling points of water is 100 degrees in each, so that the kelvin has the same magnitude as the degree Celsius. It makes sense not to have negative temperatures because temperature is based on energy of particles and particles make up everything.

What are the two laws of thermal radiation? Explain how we can use a thermal radiation spectrum for an object to determine the temperature of the object.

The Stefan-Boltzmann Law states that each square meter of a hotter object's surface emits more light at all wavelengths. Wein's law states that hotter objects emit photons with a higher average energy, which means a shorter average wavelength. In many cases we can estimate temperatures simply from the object's color. For example, at human body temperature, we emit mostly infrared light and no visible light at all. A cool star emits mostly red light. The Sun emits most strongly in green light, but it looks white or yellow to our eyes because it also emits other colors. Hotter stars emit mostly in the ultraviolet but appear blue-white. If an object were heated to millions of degrees, it would radiate mostly x-rays.

What was the political fate of the Kyoto treaty in the United States?

The U.S. signed but didn't ratify the treaty. It doesn't look like the U.S. will be participating in the Kyoto protocol in the foreseeable future.

Briefly explain the capture hypothesis for the origin of the solar system. Name and briefly explain three arguments that tend to contradict this hypothesis.

The capture hypothesis states that the sun formed by itself and then captured passing planets into orbit. One problem with this is that, again, space is too big. Everything is too far apart to be captured in by a gravitational pull. Also, orbits would be randomly oriented if they were randomly captured, but all of our planetary obits are coplanar and in the same direction. Finally, capture is physically difficult. To capture, something must slow the object down and in space things are too far apart and there is no gravity in space to slow things down.

Briefly explain the catastrophe hypothesis for the origin of the solar system. Name and briefly explain two arguments that contradict this hypothesis.

The catastrophe hypothesis states that the sun formed alone from a gas and dust cloud. Then the sun collided or nearly collided with another star. Resulting debris formed into a disk of planets. One problem with this theory is that space is too big. Collisions are too rare in space because everything is so far apart. And planetary systems are too common for something so rare to happen. The second problem with this theory is that Planets would not have volatiles. Planets contain H2O, NH3, CO2, and CH4-all, which are easily destroyed by heat. If they were formed from the sun then they would be immune to heat.

Explain the difference between the letter writer's point of view and the scientific point of view.

The correlation doesn't prove a causal connection and by itself doesn't indicate which direction there is a connection. For example, the rise in teenagers with sex problems could cause the rise of sex ed classes, rural areas often participate in experimentation, and there could be a rise in a particular type of teenage population.

In addition to an increase in CO2 due to volcanic eruptions, describe two other processes that contributed methane and CO2 to the atmosphere to accelerate the warming process during the PETM era.

The drying, baking, or burning of any material that is (or once was) living emits greenhouse gasses. Droughts would have most likely dried out forests and peat lands and in some cases, causing widespread wildfires, releasing even more CO2 to the atmosphere. The second process is thawing permafrost in Polar Regions. Permafrost is permanently frozen ground that locks away dead plants for millions of years. When the permafrost defrosts, microbes consume the thawing remains emitting a lot of methane.

How does an electrolyzer convert electricity into stored energy? How does a fuel cell release this stored energy for use? What currently limits this kind of process from widespread use in homes?

The electrolyzer is a device that splits up the charges of water. We use it as a battery to store energy. The Hydrogen and Oxygen are stored in separate compartments and when ready, they come together to make heat. It's very large and expensive. it takes a lot to fuel a household and it's not safe to put a tank of hydrogen under your home.

Even if we were to stop emitting Carbon altogether today, the climate would continue to warm for at least another couple of decades, if not longer. Explain why.

The inertia in the climate results from a combination of factors such as the heat capacity of the world's oceans and the millennial timescales needed for the circulation to mix heat and carbon dioxide throughout the ocean to create an equilibrium.

Explain "why the planes don't land"

The planes don't land because there is no war and they have no way to neither arrange for nor pay for goods to be flown in. It's not enough to just set up a runway. If they don't arrange for goods to be flown in and pay for those goods, then goods won't be flown in and the planes won't land. In order to pay for those goods, the people need wealth in their system.

What is the primary difference between a scientific and a non-scientific belief? What is the major weakness of using irrefutable beliefs as a basis for a system of knowledge?

The primary difference between a scientific belief and a non-scientific belief is how vulnerable the ideas are allowed to be. The major weakness of using irrefutable beliefs as a basis for a system of knowledge is that they could be true, but they can't be proved false. Everything to an irrefutable belief is very compelling, and everything is explained, but when one irrefutable belief contradicts another, there's no way to choose between them. We're left with this "maybe belief."

What is the Keeling curve? Why does it go up and down during the Spring and Fall?

The scale measures CO2 over time. It goes up in fall and down in spring because plans sequester CO2 in spring as they grow. However, in the fall it goes up because as plants and trees die and decay they release CO2 back in the air.

Briefly explain the difference between thermal energy and temperature. Explain why can you safely put your arm in a 400 degree oven (for a brief time) but you cannot do the same for a pot of (212 degree) boiling water

Thermal energy measures the total kinetic energy of all the randomly moving particles in a substance. Temperature measures the average kinetic energy of the particles. The air in the oven is much higher in temperature than the water in a boiling pot, but you burn your hand in the pot because of density. Molecules striking your skin transfer thermal energy to molecules in your arm. The higher temp in the oven means the air molecules strike your skin harder than the water, but since the density of the water is so much higher than air, there are more molecules striking your skin each second than in the oven.

According to the fossil fuel industry, increases in Carbon Dioxide will act like "plant food" and accelerate the growth of forests and other plant life. Explain how this hypothesis is being tested and whether the test confirms the hypothesis.

They have forest reservations where they jet CO2 in the atmosphere and record the growth of trees. The trees grew faster, so they thought they proved the hypothesis, but there are some flaws. One, more CO2 doesn't necessarily mean plant food. For example, Venus has a lot of CO2, but it is a hellacious wasteland.

Explain the difference between weather and climate. Why is local temperature variation not really important in terms of global warming?

Weather is day to day and caused by random forces. For example, a rainy day in september. Climate is the global average. It isn't hard to predict because it is an average. It is easier to measure an aggregate than try to predict one certain day.

What prevents most countries from having nuclear reactors or weapons?

You have to separate U-238 and U-235 which is not easy to do. The technology an knowledge to enrich uranium is very hard to come by and countries that do know take part in the nuclear proliferation act, so they can't tell others how it's done.

Explain what the authors eventually discovered by the PETM that was different from previous conclusions. Also, how does the CO2 increase during the PETM compare to today's CO2 increase, and what do the authors therefore conclude about comparisons between the PETM and the modern era changes in ecology?

gas release was spread out over approx. 20,000 years-between twice and 20 times as long as anyone had projected before. The rate of injection was less than 2 pentagrams a year-a fraction of the rate that the burning of fossil fuels injects greenhouse gases into the air today. In fact, CO2 concentrations are rising probably 10 times faster now than during the PETM. This tells us that the speed of climate change has more impact on how life forms and ecosystems fare than the extent of the change. Life responds more favorably to slow changes than to abrupt ones.