Category: Astronomy homework help

What is meant by the Big Bang theory, and how do the laws of physics explain the process from the beginning of the formation of the universe to the present day?

The Big Bang theory is the most widely accepted explanation for the origin and evolution of the universe. It suggests that the universe began as an extremely hot, dense point (a singularity) around 13.8 billion years ago. This singularity then rapidly expanded, initiating the formation of space, time, and matter. The theory accounts for the current state of the universe, including its expansion, the distribution of galaxies, and the cosmic microwave background radiation.

Struggling with where to start this assignment? Follow this guide to tackle your assignment easily!

Key Elements of the Big Bang Theory:

1. Singularity: The universe originated from a singularity, an infinitely small, hot, and dense state where matter, energy, and spacetime were compressed into a single point.
2. Expansion: About 13.8 billion years ago, this singularity began to expand rapidly in an event known as the Big Bang. This expansion continues today and is responsible for the vast size of the universe.
3. Cooling and Formation of Matter: As the universe expanded, it cooled down, allowing particles like protons, neutrons, and electrons to form. These particles later combined to form atoms, primarily hydrogen and helium.
4. Cosmic Microwave Background Radiation (CMB): This radiation is considered the leftover heat from the Big Bang, providing a snapshot of the universe when it was about 380,000 years old.
5. Galactic Evolution: Over time, small density fluctuations in the early universe grew into larger structures, eventually forming galaxies, stars, and planets.

How the Laws of Physics Explain the Process:

1. General Relativity:

   • Albert Einstein’s theory of general relativity describes how gravity governs the large-scale structure of the universe. The Big Bang theory utilizes general relativity to explain the initial expansion and the current expansion of the universe. According to general relativity, the geometry of space-time is affected by the distribution of mass and energy. The early universe, being very dense and hot, caused space-time itself to expand.
   • The Einstein field equations describe how the curvature of space-time is related to the energy and momentum of the contents of the universe, which were initially very concentrated.

2. Cosmic Inflation:

   • Cosmic inflation is a rapid expansion that occurred in the first fraction of a second (around 10^-36 seconds after the Big Bang). This theory was proposed to explain the uniformity of the universe (why the universe looks the same in all directions), as well as the structure of the universe. During inflation, the universe expanded exponentially faster than the speed of light, smoothing out irregularities and leading to the universe we observe today.

3. Quantum Mechanics:

   • On extremely small scales, quantum mechanics plays a crucial role. In the earliest moments of the Big Bang, particles behaved in ways that could not be explained by classical physics alone. For example, quantum fluctuations likely helped seed the structure of the universe by creating slight variations in density that later grew into galaxies and clusters of galaxies.
   • The uncertainty principle in quantum mechanics suggests that at extremely small scales, particles could appear and disappear spontaneously, which may have contributed to the creation of matter and energy during the Big Bang.

4. Thermodynamics:

   • Thermodynamics explains how the universe cooled over time. Initially, the universe was in a hot, dense state, with temperatures so high that atoms could not form. As it expanded, the temperature decreased, allowing particles to combine and form atoms. Later, as the universe continued to cool, stars and galaxies formed.
   • The second law of thermodynamics, which states that entropy (disorder) tends to increase over time, also applies. The universe has been increasing in entropy since the Big Bang, with energy becoming more spread out as the universe expands.

5. Nucleosynthesis:

   • During the first few minutes after the Big Bang, the universe was hot and dense enough for nuclear reactions to occur, forming the light elements like hydrogen, helium, and trace amounts of lithium in a process known as Big Bang nucleosynthesis. This process was governed by the laws of nuclear physics and chemistry.

From the Big Bang to Today:

• The Early Universe: In the first few moments after the Big Bang, the universe was a dense, hot soup of fundamental particles. As it expanded and cooled, particles began to combine into atoms, and the universe became transparent to light, leading to the cosmic microwave background radiation that we observe today.
• Formation of Galaxies and Stars: Over billions of years, matter began to clump together under the force of gravity, leading to the formation of galaxies, stars, and eventually solar systems.
• Continued Expansion: The universe continues to expand today, a phenomenon that is described by Hubble’s Law, which states that galaxies are moving away from us, with the speed proportional to their distance. This suggests that the universe is still expanding from the initial Big Bang.

In summary, the Big Bang theory, along with the laws of physics (general relativity, quantum mechanics, and thermodynamics), provides a comprehensive framework for understanding the origin, evolution, and ongoing expansion of the universe from the Big Bang to the present day.

 Instructions
Learning Objective:
To become familiar with one of the most commonly used tools for understanding stars, the HR diagram
Prerequisites: Read Chapter 15
Materials Required
Computer and internet access
Digital camera or scanner
HR Diagram Graph: download and print out, or you may create your own graph but using similar axes
Time Required: approximately 3 hours
Exploration Study and Information
Properties of Stars
The Hertzsprung-Russell Diagram, or HR Diagram, is a graph in which a star’s temperature is plotted against its absolute magnitude. From such a diagram, other information about a star’s properties and life cycle can be determined. A simplified HR Diagram appears in your textbook and is shown below for reference. Note that this diagram shows the different categories of types of stars, such as the Main Sequence, Giants, etc.. In this laboratory, you will construct an HR Diagram using data on the 20 stars that are nearest to our Sun and the 20 brightest stars in our sky. Then you will use the finished diagram to describe the properties and life cycle of stars. And then you will use a simulation where you will follow the life stages of our Sun on this diagram.
Image 1. H-R Diagram. Bennett, J., Donahue, M., Schneider, N., & Voit, M. (2019). Cosmic Perspective, The (9th ed.). Pearson.
Part 1 – Creating Your Own HR Diagram.
Instructions
You will be using Table 1 and Table 2 to plot the 20 nearest and 20 brightest stars on the attached HR diagram.  The following tips will be helpful when graphing stars;
Temperature is on the horizontal axis, absolute magnitude is on the vertical axis,
Absolute magnitude decreases as the values become more positive,
Notice the graph lines used to plot temperature are unevenly spaced and that the number of Kelvins between each line is not constant.  Carefully check a star’s temperature and the value of its graph line before plotting each star.
Use a plus sign (+) to graph each of the nearest stars (listed in Table 1) on the diagram.
Use a circled dot (o) to graph each of the brightest stars as seen from Earth (listed in Table 2) on the diagram.  Show stars that appear on both tables using a square ().  Please sign you name on your graph and include the date.
Table 1. The 20 Nearest StarsNameDistance (Parsecs)Temperature KAbsolute MagnitudeAlpha Centauri
1.31
5,800
+4.4
Barnard’s Star
1.83
2,800
+13.2
Wolf 359
2.35
2,700
+16.8
Lalande 21185
2.49
           3,200
+10.5
Sirius
2.67
10,400
+1.4
Luyten 726-8
2.67
2,700
+15.4
Ross 154
2.94
2,800
+13.3
Ross 248
3.16
2,700
+14.7
Epsilon Eridani
3.30
4,500
+6.1
Ross 128
3.37
2,800
+13.5
Luyten 789-6
3.37
2,700
+14.9
61 Cygni
3.40
2,800
+7.5
Procyon
3.47
6,800
+2.7
Epsilon Indi
3.51
4,200
+7.0
Sigma 2398
3.60
3,000
+11.1
BD +43o44
3.60
3,200
+10.3
Tau Ceti
3.64
5,200
+5.7
CD -36o15693
3.66
3,100
+9.6
BD +5o1668
3.76
3,000
+11.9
CD-39o14192
3.92
3,500
+8.7
The 20 Brightest Stars
Name
Distance
(Parsecs)
Temperature
(K)
Absolute
Magnitude
Sirius
2.7
10,400
+1.4
Canopus
30.0
7,400
-3.1
Alpha Centauri
1.3
5,800
+4.4
Arcturus
11.0
4,500
-0.3
Vega
8.0
10,700
+0.5
Capella
14.0
5,900
-0.7
Rigel
250.0
11,800
-6.8
Procyon
3.5
6,800
+2.7
Betelgeuse
150.0
3,200
-5.5
Achernar
20.0
14,000
-1.0
Beta Centauri
90.0
21,000
-4.1
Altair
5.1
8,000
+2.2
Alpna Crucis
120.0
21,000
-4.0
Aldebaran
16.0
4,200
-0.2
Spica
80.0
21,000
-3.6
Antares
120.0
3,400
-4.5
Pollux
12.0
4,900
-0.8
Fomalhaut
7.0
9,500
+2.0
Deneb
430.0
9,900
-6.9
Beta Crucis
150.0
22,000
-4.6
Analysis and Conclusion:
Type your answers to the below questions in your lab report. Based on the results of the HR diagram you have created, answer the following questions.  For all answers use complete sentences. After you have completed the below questions, scan or take an image of your HR graph and insert it into your lab report, making sure that it is clear and readable. Make sure to provide any/all sources used.
Compare the two star lists.  Name any stars that happen to appear on both lists.
What does your answer to Question 1 indicate about the nearest stars?  Are the nearest stars also the brightest stars as seen from the Earth?
A star located in the lower right portion of the diagram is cool and dim.  What are the characteristics of a star in the upper left of the diagram?  What are the characteristics of a star in the upper right of the diagram?
Refer to the HR Diagram of your textbook or other source.  To which group do most of the stars on your diagram belong?
According to your diagram are any of these stars white dwarf stars?  What is the evidence for your answer?
Our Sun has a temperature of 6,000K and an absolute magnitude of +4.7.  Use an asterisk (*) to show the location of the Sun on your diagram.  To which group does the Sun belong?
In a paragraph of 2-3 sentences compare the absolute magnitude and temperature of the Sun with those of other stars in its group.  
Betelgeuse is 150 parsecs away and has a surface temperature of only 3,200K yet Betelgeuse is one of the brightest stars as seen from the Earth.  What does this indicate about the size of Betelgeuse?  Is your answer supported by the location of Betelgeuse on the diagram?
On your diagram there is another star plotted near Betelgeuse.  What is the name of this star?  What kind of star is it?
Compare our Sun with stars that are considered to be Red Giants.  Which star is further along in its life cycle?  How do you know?
Part 2 – HR Diagram Simulation: Evolution of the Sun
Instructions
Follow this link to an H-R Diagram Simulation.
When you open the simulation you will see an image of two stars, one labeled “Test Star” and one labeled “Sun”.  The default setting when you open the simulation is for the star to have the same settings as the Sun for all values of temperature, luminosity, and radius. (T = 5,800K, L = 1sun, R = 1 sun).  You can change the settings in various ways, clicking on the slider bars for temperature and luminosity, or clicking on various spots on the HR diagram to move the red crosshair shown on the diagram. Below is a screenshot of the Hertzsprung-Russell Diagram Simulation.
TIP: Hit the “Reset” button any time on the simulation to continue exploring.
Image 2: H-R Diagram simulation.
Navigating the HR Diagram Simulation
Use the H-R Diagram Simulation and outside sources to answer the Simulation and Lab Questions (below). You will also be asked questions where you will need to consult other sources. Keep track of our sources so you can easily include APA citations for any outside source used. For some of the questions, you can refer to the H-R Diagram shown above in these lab instructions. You may also use the below as a reference image.
Image 3: H-R Diagram from NAAP Labs.
Simulation and Lab Questions
Near the bottom right corner, click on the button to display the “nearest stars.” Describe the relationship in terms of temperature, luminosity, and radius of the nearest stars to the location of the Sun on the diagram. Which luminosity group(s) do these stars lie in?
Click off the “nearest stars”, and now click on “brightest stars.” Describe the relationship in terms of temperature, luminosity, and radius of the nearest stars to the location of the Sun on the diagram. Which luminosity group(s) do these stars lie in?
The next series of questions will ask you to move the red crosshairs on the diagram to different spots within the diagram to understand the evolution of our Sun and the changes that it will experience with time.
The Sun as it ages will grow in size and move off of the main sequence into an area of the diagram called the “instability strip.” Research and briefly describe in your own words what the characteristics of the instability strip are. And list the types of stars that can be found in the stability strip. Be sure to properly cite your sources.
Move the crosshair into the instability strip, based on your research, so it is approximately in the middle of the group. Write on a slip of paper your name and the date.

Hold the paper with your name next to the image on your computer and take a photo. Insert this into your lab report.

When it is in the instability strip, describe the changes that will occur with the Sun in terms of color, temperature, luminosity, and radius.

This data can be gathered from the simulation-based on where your crosshairs are positioned.
Briefly describe in your own words why these changes are occurring. Remember to supply your sources.

The next stage in the life of the Sun as it ages is the “Red Giant” luminosity class. Move the crosshair to the Red Giant class (a good spot would be just above the “an” in “Giants III” on Image 3 above). Describe the changes that will occur with the Sun in terms of color, temperature, luminosity, and radius.
The last stage in the life of the Sun as it ages is the “White Dwarf” luminosity class. Move the crosshair to the White Dwarf class (a good spot would be just above the “s” in “White Dwarfs” on Image 3 above). Describe the changes that will occur with the Sun in terms of color, temperature, luminosity, and radius.
As a White Dwarf, the Sun has decreased significantly in size. What happened between the Red Giant and White Dwarf classes to cause this? (Consult outside sources.)
Our Sun, however, is not big enough to be a Super Giant star, this only happens to the very highest mass stars.  Move the crosshair back to the main sequence but to an area of R=10sun  (a good spot would be just above the “rf” in “Dwarfs (V)” on Image 3 above). Describe the differences between this star and our Sun in terms of color, temperature, luminosity, and radius.
This star, from Question 3g, will become a Super Giant. Move the crosshair into the “Super Giant” class  (a good spot would be just above the “gi” in “Supergiants (I)” on Image 3 above). Describe the differences with this star in terms of color, temperature, luminosity, and radius.
In a paragraph (minimum of 50 words) summarize what you have learned from both Parts 1 and 2 of this laboratory activity. What are some implications for the Earth as the Sun ages and moves through the different phases of its evolution?
NOTE: You must provide a reference list showing the source(s) that you used, including our own textbook, in proper APA citation format.
Submit
Submit your lab to the corresponding assignment folder. Ensure that you have your name and date on your HR diagram plot that you photo.
Rubric:
All questions are answered AND/OR activities completed.
Required: Lab report is typed, (if report is not typed and can’t be read by the originality checker, this may result in a zero score for entire lab.) Name and Date is given, if you had a lab partner their name is listed. AND Answers to questions are clearly labeled & extra lab content/instructions has been removed. AND/OR Name and date are shown in required drawings/photos noted in the instructions (Labs 1, 2, 3, 4, 5, 7, 8, 9, and 10).
All answers are in complete sentences and responses include details showing a thorough understanding of concepts. AND Responses are clear and articulate. AND Any needed graphs/tables/drawings are correct AND for any questions that require calculations, all major steps are shown, and at a minimum a sample calculation is given for data in tables.
Only reliable references are used and all quoted data is referenced properly with correctly formatted APA citations.