Cosmology: Big Bang, Expansion & Dark Matter
Cosmology: Big Bang, Expansion & Dark Matter
💡 Key Takeaways
- Explain the Big Bang model and the main evidence supporting it (cosmic microwave background, primordial element abundances).
- Describe cosmic expansion using redshift and Hubble's law and what it reveals about the universe's growth.
- Define dark matter and how its presence is inferred from galaxy rotation curves and large-scale structure.
- Outline the methods scientists use to study dark matter, including gravitational effects and indirect detection.
❓ Frequently Asked Questions
What is the Big Bang theory?
The standard model of the universe's origin, describing a hot, dense state about 13.8 billion years ago that expanded and cooled to form the cosmos we see today.
What does cosmic expansion mean, and how do we know it?
Space itself is expanding, causing distant galaxies to move apart. We know from redshifted light, Hubble's law, and the cosmic microwave background.
What is dark matter, and why do scientists think it exists?
Dark matter is matter that does not emit or absorb light but exerts gravity; its presence is inferred from galaxy rotation curves, gravitational lensing, and CMB observations.
How do scientists test ideas about the Big Bang and dark matter?
By comparing theoretical predictions with observations such as the cosmic microwave background, supernova distances, and large-scale structure surveys.
Is dark matter the same as dark energy?
No. Dark matter adds gravitational mass that helps structure formation; dark energy drives the universe's current accelerated expansion.