Lecture Notes: Redshift and The Big Bang Theory

Introduction

• Topics Covered: Redshift, Big Bang Theory
• Central Idea: Universe is expanding; galaxies are moving away from Earth

Redshift Explained

Absorption Spectra

• Definition: Patterns of dark lines in light spectrum due to absorption by chemicals
• Example: Sun's light spectrum shows dark lines where chemicals like oxygen and hydrogen absorb specific wavelengths

Observations in Distant Galaxies

• Description: Spectra from distant galaxies show dark lines shifted towards the red end
• Explanation: Light waves are stretched as they travel to Earth, leading to redshift
• Reason: Galaxies are moving away from us, not through space, but due to space expansion

Space Expansion Model

• Model: Universe as a balloon with markers (galaxies)
• Process: Balloon inflates (universe expands), markers move apart due to space stretching
• Observation: From any galaxy's perspective, others appear to move away

Importance of Distance

• Observation: More distant galaxies move away faster

Limitations of Models

• Balloon Model: Limited stretch, unlike the universe
• Reality: Galaxies are not just on the surface

Big Bang Theory

Universe Expansion

• Inference: Past universe was smaller; initially tiny
• Question: How did it expand to current size?

The Big Bang

• Definition: All universe's matter initially in a tiny, dense, hot space
• Event: Sudden explosion led to expanding space
• Status: Expansion continues today

Conclusion

• Summary: Redshift indicates universe expansion; Big Bang Theory provides an explanation
• Call to Action: Share the knowledge

This concludes the lecture notes on redshift and the Big Bang theory. Understanding these concepts helps in comprehending the expanding nature of the universe.