Red shift | Astrophysics | Physics | FuseSchool

Summary

This video explores the concept of the expanding universe through the work of Edwin Hubble. By examining the light from distant galaxies, Hubble discovered that their light was redshifted, meaning they were moving away from us. This phenomenon, explained by the Doppler effect, provides evidence that the universe is growing. The further a galaxy is, the faster it moves away. This redshift also supports the Big Bang theory. The video highlights Hubble's groundbreaking observations, demonstrating how redshift helps us understand the vast and ever-expanding nature of the universe.

Takeaways

• 😀 The universe is vast and constantly expanding.
• 😀 Edwin Hubble played a key role in discovering the expanding universe.
• 😀 Before Hubble, scientists believed the universe was small and static.
• 😀 The light from stars contains specific wavelengths that help determine their chemical makeup and distance.
• 😀 The Doppler effect explains how the wavelength and color of light change based on the motion of the light source.
• 😀 A redshift occurs when a star or galaxy is moving away from Earth, causing its light to shift toward the red end of the spectrum.
• 😀 Hubble observed that most galaxies' light was redshifted, indicating they are moving away from us.
• 😀 The more distant a galaxy is, the more its light is redshifted, and the faster it is moving away from us.
• 😀 Redshift provides evidence for the expanding universe and supports the Big Bang theory.
• 😀 By comparing atomic spectra from different stars, we can identify how far away they are and their motion relative to Earth.

Q & A

What is the main evidence for the universe expanding?

The main evidence for the expanding universe is redshift, which is observed when the light from distant galaxies is shifted towards the red end of the spectrum.

Who was Edwin Hubble, and what did his work reveal?

Edwin Hubble was an American astronomer who discovered that most galaxies are moving away from us, with the further galaxies moving faster. This observation led to the conclusion that the universe is expanding.

What are Fraunhofer lines, and what do they tell us?

Fraunhofer lines are black lines in the light spectrum of a star that show where light is absorbed by elements in the star’s atmosphere. They help us determine the chemical makeup of the star and its relative distance from Earth.

What does the Doppler effect describe?

The Doppler effect describes the change in frequency or wavelength of a wave, such as light or sound, when the source of the wave is moving relative to the observer.

Can you explain the change in pitch of a siren you hear as a police car passes?

The change in pitch of the siren as a police car passes is an example of the Doppler effect. As the car moves toward you, the sound waves are compressed (higher pitch), and as it moves away, the waves are stretched (lower pitch).

How does the Doppler effect apply to light from distant galaxies?

When light from a distant galaxy moves away from us, the wavelength stretches, causing the light to shift towards the red end of the spectrum. This is known as redshift.

What did Hubble observe about the redshift in galaxies?

Hubble observed that the further away a galaxy is, the more its light is redshifted. This indicates that galaxies are moving away from us and supports the idea of an expanding universe.

What does redshift tell us about the movement of galaxies?

Redshift indicates that galaxies are moving away from us, with the amount of redshift increasing as the distance between the galaxy and Earth increases.

How does redshift provide evidence for the Big Bang theory?

Redshift shows that galaxies are moving away from each other, suggesting that the universe was once much smaller and has been expanding since the Big Bang.

Why does the universe appear to be expanding constantly?

The universe is expanding because galaxies are observed to be moving away from us, with the further galaxies moving faster. This ongoing expansion is supported by the redshift evidence observed in distant galaxies.