Explore 2.13 The Nature of the Big Bang and Evolving Universe
Learning Objectives
By the time you have completed the 2.13. Introduction & Exploration Activities, you should be able to:
Define the cosmic microwave background radiation (CMB) and explain that it originated in the aftermath of the Big Bang.
Understand the broad-scale development of the Universe, from the Big Bang to today (i.e., it expanded, cooled, and complexified). Also, describe whether the Big Bang Theory seeks to explain the origin or the development of the Universe.
Explain three predictions of Big Bang Theory (e.g., an expanding, cooling, complexifying Universe; the cosmic microwave background radiation; etc.) and identify if these predictions have been observed.
CMB - Cosmic Microwave Background Radiation
Answer the questions below.
What does CMB stand for?
Answer
Cosmic Microwave Background Radiation
What is Cosmic Microwave Background Radiation?
Answer
Big Bang Theory predicts the existence of high energy light produced in the early Universe.
First developed in the 1940s, this prediction includes the specific wavelength and effective
temperature of this light. Basically, if radiation existed in the beginning of the universe, there should be some remnant of that radiation still today. That residual radiation, or light, is called Cosmic Microwave Background Radiation.
Watch this video (5 minutes) to gain a better understanding of Cosmic Microwave Background Radiation.
Big Bang Theory
The Big Bang Theory tells a fairly simple, uncontroversial story about the development of the material Universe: hot dense energy expanded and cooled; as it did, ever-lower temperatures allowed progressively complex states of matter to emerge; and as things cooled, gravity acted to pull them together and motion worked to spread them apart.
Define the Big Bang Theory.
Answer
The Big Bang Theory makes detailed quantitative predictions about how the Universe changed as it expanded from an initial state that was incredibly small, simple, dense, and hot. Basically, the entire universe was once an incredibly small, dense, primeval atom that expanded into the universe we see now and is continuing to expand.
Predictions of Big Bang
To help you deepen your understanding of the predictions of Big Bang Theory, answer the questions below, which compare predictions and observations.
Is the night sky mostly dark, as predicted by Big Bang Theory? Or is it completely light, as predicted by the Newtonian Model of the Universe?
Answer: The sky is dark at night. The Big Bang predicts that the night sky should be dark.
The sky is dark at night. The Big Bang predicts that the night sky should be dark.
What is the age distribution of the oldest stars and galaxies?
Answer: The ages of the oldest stars and galaxies are uniformly ancient, between 12 and 13.5 billion years old. The Big Bang predicts that the most ancient stars and galaxies formed shortly after the Big Bang, so their ages should be old.
The ages of the oldest stars and galaxies are uniformly ancient, between 12 and 13.5 billion years old. The Big Bang predicts that the most ancient stars and galaxies formed shortly after the Big Bang, so their ages should be old.
What two elements compose the bulk of every star whose composition humanity has measured?
Answer Every star consists mostly of H & He—in the exact ratio predicted by the Big Bang (92% H & 8% He).
Every star consists mostly of H & He—in the exact ratio predicted by the Big Bang (92% H & 8% He).
Has the abundance of heavy elements in stars changed as the Universe developed?
Answer: Yes, the abundance of heavy elements in stars has increased with each successive generation of element-forming stars—just as Big Bang Theory predicts.
Yes, the abundance of heavy elements in stars has increased with each successive generation of element-forming stars—just as Big Bang Theory predicts.
Has the size, complexity, type, and elemental composition of galaxies changed through time?
Answer: Yes, early galaxies were mostly small, simple spirals with few heavy elements. Today, galaxies are mostly larger, more complex, elliptical, and contain more heavy elements.
Yes, early galaxies were mostly small, simple spirals with few heavy elements. Today, galaxies are mostly larger, more complex, elliptical, and contain more heavy elements.
Has the CMB been observed? If so, do the attributes of the CMB (wavelength & temperature) match the predictions of Big Bang Theory.
Answer: Yes to both questions: the CMB has been observed, and its attributes are precisely those predicted by Big Bang Theory.
Yes to both questions: the CMB has been observed, and its attributes are precisely those predicted by Big Bang Theory.
