Space and relativity

• What is a light year?

  The distance travelled by light in one year
• How is a light year defined?

  Distance travelled by electromagnetic wave in a year
• How can distances in the sky be measured using parallax?

  By measuring angles at different times
• What is redshift?

  Apparent increase in wavelength of light
• What does redshift from distant galaxies suggest?

  Distant galaxies are moving away from us
• What does a greater redshift indicate about a galaxy?

  The galaxy is moving away faster
• What theory does the redshift of distant galaxies support?

  The Big Bang Theory
• What is Hubble’s Law?

  Recessional velocity is proportional to distance
• What relationship is used to calculate the proportional change in wavelength?

  $\frac{\Delta \lambda}{\lambda} =$$\frac{v}{c}$
• What does CMBR stand for?

  Cosmic Microwave Background Radiation
• What does CMBR provide evidence for?

  The Big Bang Theory
• What was Einstein’s First Postulate for his Theory of Special Relativity?

  Physics laws are the same for all observers
• Where is CMBR believed to originate from?

  Gamma rays from the Big Bang
• What happens to the wavelength of radiation from CMBR as the universe expands?

  The wavelength has been stretched
• What was Einstein’s Second Postulate for his Theory of Special Relativity?

  The speed of light is a universal constant
• What is time dilation?

  Different observers record different event times