Physics Quiz: Redshift and Expanding Universe

What is the first piece of evidence that showed our universe is expanding?

• Dark lines in the spectra from galaxies

• Spectrum of the sun

• Light from distant galaxies

• Red-shifted light

What is the usual explanation for the redshift of light from distant galaxies?

• Photons interacting with dark energy

• Photons being absorbed and re-emitted by galaxies

• Photons losing energy in gravitational fields

• Photons becoming stretched in expanding space

What are the three different types of redshift discussed by physicists?

• Doppler Redshift, Gravitational Redshift, and Cosmological Redshift

• Einstein Redshift, Newtonian Redshift, and Quantum Redshift

• Relativistic Redshift, Quantum Redshift, and Gravitational Redshift

• Doppler Redshift, Quantum Redshift, and Relativistic Redshift

What is the equivalence principle according to the video?

• All observers measure the same wavelength of light

• Being at rest on Earth’s surface is indistinguishable from being in a rocket in deep space accelerating up at 1g

• The universe is expanding at a constant rate

• The wavelength of light is intrinsic to photons

What is the basic property of an expanding universe?

• The density of the cosmic fluid is increasing over time

• The density of the cosmic fluid is decreasing over time

• The cosmic fluid is stationary

• The cosmic fluid is contracting over time

What is the standard explanation for cosmological redshift?

• The photon’s wavelength is stretched by the amount the universe has expanded during its journey

• The photon’s wavelength is compressed by the amount the universe has expanded during its journey

• The photon’s wavelength is stretched by the amount the universe has contracted during its journey

• The photon’s wavelength remains constant during its journey

What does the video suggest about redshifting photons and expanding space?

• Redshifting photons are a result of electromagnetic forces pulling on everything

• Redshifting photons do not mean space is expanding and pulling on everything

• Redshifting photons indicate that space is contracting and pulling on everything

• Redshifting photons are a result of dark energy pulling on everything

What is the reason for molecules, stars, galaxies, and humans not expanding with the universe?

• They are moving at a constant velocity

• They are not affected by gravitational fields

• They are too small to be affected by expanding space

• They are held together by electromagnetic forces

What is the take-home message of the video regarding the expansion of the universe?

• Everything in the universe is expanding at the same rate

• Redshifting photons don’t mean space is expanding and pulling on everything

• The universe is expanding at a constant rate

• The expansion of the universe is caused by dark energy

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