Physics draft
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School
The University of Queensland *
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Course
QCE
Subject
Astronomy
Date
Apr 3, 2024
Type
docx
Pages
4
Uploaded by DeaconDove3835
Rationale
Claim
: The universe has existed forever and has always looked the same at all times
This claim was broken down into main parts: the universe existing forever, and the universe staying the same at all times. In order to start initial research, a broad research question stating, ‘how has the universe changed over time?’ was formulated. Research found that the most accepted theory on how the universe was created is the big bang theory (
Origins of the Universe 101
, n.d.). The big bang theory states that the universe was created around 13.8 billion years ago from an infinitely hot and dense point that inflated and stretched (May & Howell, 2023). Although current technology does not allow astronomers to look back to the universes birth, evidence such as cosmic microwave background radiation, elemental composition and red shift of light help support the big bang theory. Cosmic microwave background (CMB) is the left over radiation
from the big bang or when the universe began (Howell & Dobrijevic, 2022). Red shift also gives evidence that the universe is constantly expanding and moving away from a central point. Lastly, the elemental composition of the universe also support the big bang theory, as the abundance of light elements (hydrogen, and helium) are consistent with the amounts that would have been produced soon after the big bang (
Big Bang Theory
, n.d.). Therefore, it became the focus of the research question.
Research question How does cosmic background radiation, red shift of light, and elemental composition prove the creation of the universe and that it is constantly changing? Evidence In 1929, a scientist by the name of Edwin Hubble discovered that there were other galaxies beyond our own, and the universe was expanding at a constant rate. This constant expansion of the universe was seen through the red shift of light. Red shift occurs when objects that emit light and are constantly moving away from the observer. This causes the light waves that are being emitted to become more stretched or compressed than usual, depending on whether the objects is moving towards or away from the observer. When the objects is moving away from the observer the light waves are stretched, causing the frequency to decrease and wavelength increase (
Astronomical Redshift
, n.d.). The increase in wavelength causes the light that reaches the observer to be shifted more towards the red end of the electromagnetic spectrum, thus red shift occurs (shown in figure 1).
Figure 1: Representation of redshifted light (
Astronomical Redshift
, n.d.)
Thus, Hubble created a law stating that the distance of a star and the speeds of recession were directly proportional to each other. The law can be seen below:
v
=
H
0
D
v
= recessional velocity (redshift)
H
0
= Hubble’s constant
D
= proper distance
If the universe has always looked the same at all times, there would be no correlation between distance and velocity (shown in figure 2). However, if the universe was constantly expanded, it would
be expected that there would be a correlation between distance and velocity. Hubble’s law and the discovery of red shift are proof of the ever changing and ongoing expansion of the universe, disproving the claim that the universe has always looked the same at all times. Figure 2: Graph showing the relationship between redshift and distance (Google images, unknown)
The CMB is able to give insight into what the universe was like long ago. The big bang theory states that the universe started from and infinitely dense and hot single point, which was full of radiation. As the universe cooled, this radiation was released (Pattison, 2022). The released radiation from the big bang is what is known as cosmic microwave background radiation. CMB could also be considered the ‘shockwave’ that came shortly after the big bang occurred. The most abundant element in the universe being hydrogen also supports the theory of the big bang.
During the hadron epoch the universe cooled down enough for quarks to be able to bind together to form protons and neutrons (quote the book). Then during the lepton and nuclear epochs, the protons and neutrons underwent fusion and created nuclei, thus creating the first element in the universe hydrogen. Hydrogen being the most abundant is due to only consisting of one proton, this meant that it was the easiest element to form during the lepton and nuclear epochs. This caused hydrogen to become the most abundant element within the whole universe. Interpretation The research shows that the red shift is proof for the universe constantly expanding, and that the red
shift of a light source and the distance are directly proportional. Furthermore, the CMB and the elemental composition give evidence for the creation of the universe. Hence, the research opposes the claim.
Evaluation Although the evidence came from a range of sources, the main three pieces of evidence came from IOWA physics and astronomy, Christopher Pattison, and the dictionary of astronomy by Ian Ridpath. The source of information covering the red shift came from Iowa university which is considered a reliable source. This is as based on 66 evaluation metrics University of Iowa is rated number 131 (out of 1148; top 15%) for their physics program in America (
Physics Schools
, 2022). Meaning it would be assumed for the data and information released on the university website to be a credible source. This shows that the information regarding the red shift is reliable. Chirstopher Pattison was the author of the article regarding CMB radiation. He completed his PhD in May 2020, however it does not state what he has a PhD in possibly making the data unreliable. A limitation within the research was the age of one of the data sources which impacts its reliability. Although the concepts discussed were still discovered before the publication of the book, there may be new and updated concepts that may not be found in the book. Furthermore, a limitation within all sections of the evidence, is that the majority of the research for each section only came from one source. This would have impacted the validity as there was no corroboration of evidence from outside reliable sources. Conclusion Improvements and extensions
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Dictionary of astronomy Ian,s.R
Physics schools
. (2022). Retrieved September 6, 2023, from https://physics-schools.com/university-of-iowa
Pattison, C. (2022, August 14). Curious Kids: How does cosmic microwave background radiation work? Space.com
. https://www.space.com/curious-kids-cosmic-microwave-
background-radiation-science
Origins of the Universe 101
. (n.d.). https://education.nationalgeographic.org/resource/origins-
universe-101/
May, A., & Howell, E. (2023). What is the Big Bang Theory? Space.com
. https://www.space.com/25126-big-bang-theory.html
Howell, E., & Dobrijevic, D. (2022). What is the cosmic microwave background? Space.com
.
https://www.space.com/33892-cosmic-microwave-background.html
Big Bang Theory
. (n.d.). https://people.highline.edu/iglozman/classes/astronotes/bigbang.htm