Cosmology
Übersicht
About 14 billion years ago, everything in the universe was compressed into a single, incredibly hot, dense point. Then it exploded outward in an event we call the Big Bang, and it has been expanding ever since. The evidence for this remarkable claim comes from two independent observations: the red-shift of distant galaxies and the faint microwave glow that fills every corner of the sky.
In this lesson you will learn how the Doppler effect stretches light from receding galaxies, how this red-shift reveals that the universe is expanding, and how the cosmic microwave background radiation provides a snapshot of the early universe. You will also use the red-shift equation and explore how astronomers estimate the age of the universe. These ideas are tested on Edexcel Papers 1 and 2, often as explain-the-evidence questions.
Ziele
- Describe the past evolution of the universe and the main arguments in favour of the Big Bang theory
- Describe evidence that supports the Big Bang theory (red-shift and cosmic microwave background radiation)
- Describe that if a wave source is moving relative to an observer, there will be a change in the observed frequency and wavelength
- Use the equation relating to change in wavelength, reference wavelength, velocity of a galaxy and the speed of light: (lambda - lambda0) / lambda0 = v / c
- Describe the red-shift in light received from galaxies at different distances away from the Earth
- Explain why the red-shift of galaxies provides evidence for the expansion of the universe
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Unterrichtsbewertung
Herzlichen Glückwunsch zum Abschluss der Lektion über Cosmology. Jetzt, da Sie die wichtigsten Konzepte und Ideen erkundet haben,
Sie werden auf eine Mischung verschiedener Fragetypen stoßen, darunter Multiple-Choice-Fragen, Kurzantwortfragen und Aufsatzfragen. Jede Frage ist sorgfältig ausgearbeitet, um verschiedene Aspekte Ihres Wissens und Ihrer kritischen Denkfähigkeiten zu bewerten.
Nutzen Sie diesen Bewertungsteil als Gelegenheit, Ihr Verständnis des Themas zu festigen und Bereiche zu identifizieren, in denen Sie möglicherweise zusätzlichen Lernbedarf haben.
- What does it mean when light from a distant galaxy is red-shifted? A) The galaxy is getting hotter B) The galaxy is moving towards Earth C) The galaxy is moving away from Earth D) The galaxy is slowing down Answer: C
- The cosmic microwave background radiation has a temperature of approximately: A) 0 K B) 2.7 K C) 273 K D) 6000 K Answer: B
- What happens to the red-shift of a galaxy as its distance from Earth increases? A) It decreases B) It stays the same C) It increases D) It changes to blue-shift Answer: C
- Which of the following is NOT evidence for the Big Bang theory? A) Red-shift of galaxies B) Cosmic microwave background radiation C) Stars emitting light D) More distant galaxies receding faster Answer: C
- A spectral line has a reference wavelength of 500 nm. It is observed at 520 nm from a galaxy. The red-shift value (z) is: A) 0.02 B) 0.04 C) 20 D) 0.96 Answer: B
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Lehrbuchabschnitt
Cosmology and Particle Physics
Look at the sky on some clear night when you are away from city lights. There you will see thousands of individual stars and a faint glowing background of millions more. The Milky Way, as it has been called since ancient times, is an arm of our galaxy of stars—the word galaxy coming from the Greek w
"College Physics: Cosmology and Particle Physics" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/college-physics/pages/34-1-cosmology-and-particle-physics. Access for free at https://openstax.org/books/college-physics/pages/1-introduction
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Lehrbuchabschnitt
Doppler Effect and Sonic Booms
Describe the Doppler effect of sound waves
"Physics: Doppler Effect and Sonic Booms" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/physics/pages/14-3-doppler-effect-and-sonic-booms. Access for free at https://openstax.org/books/physics/pages/1-introduction
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