The Nature Of Light
What is the electromagnetic spectrum, and what types of radiation does it include?
The arrangement of electric and magnetic energy by wavelength that travels through space. It includes gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves, and radio waves.
How are an absorption spectrum and an emission spectrum created?
This spectrum is created when white light passes through a cool gas, leaving dark lines. Its opposite is a series of bright lines produced by a hot gas.
According to the Big Bang Theory, what was the initial state of the universe approximately 14 billion years ago?
Approximately 14 billion years ago, the entire universe was confined to a bubble thousands of times smaller than a pinhead, in an infinitely hot and dense state before it suddenly expanded.
Explain the dual nature of light
Light behaves like waves in some instances and like particles in others. The particle nature is represented by a small packet of light energy.
What can an absorption spectrum and an emission spectrum reveal about a star?
These are a set of bright lines (or dark lines on a continuous background) that act as "fingerprints" to identify the elements present in a star or gas cloud.
What is Cosmic Microwave Background (CMB) radiation and why is it considered evidence for the Big Bang?
This faint microwave glow in space is the cooled-down heat from the original Big Bang explosion, showing the universe was once uniform and hot.
Define the term "photon."
A small packet of light energy that represents the particle nature of light.
How does the chemical composition of ancient stars (like Pop III stars) support the Big Bang theory?
These stars are made from "primordial material" and contain a composition of mostly hydrogen and helium, contrasting with newer stars.
Explain the concept of Redshift and its connection to Hubble's Law.
This law states that galaxies are retreating from us at a speed proportional to their distance, and it provides evidence that the universe is expanding at an accelerating rate.
What are X-rays primarily used to study in astronomy, and why is space-based study necessary for them?
These high-energy waves are produced by hot objects and are used to visualize galactic centers and supernova remnants. Space-based study is necessary because they're absorbed by Earth's atmosphere.
What is a series of bright lines produced by a hot gas under low pressure?
An emission spectrum.
Describe the key events that occurred during the Particle Era of the universe.
This era occurred 0.001 seconds into the universe, during which electrons and quarks—the building blocks of atoms—emerged.
Explain the concept of Redshift.
This is a Doppler shift toward the red end of the spectrum, which occurs because light waves from distant galaxies are "stretched" as they move away from us.
What is the spectrum created when white light passes through a cool, low-pressure gas, which absorbs specific wavelengths, leaving dark lines?
An absorption spectrum.
Name and briefly describe the three potential scenarios for the end of the universe.
The Big Crunch, the Cold Death (Big Freeze), and the Big Rip.