Question

Which of the following gives the basis for the observation that the universe is expanding?

• A. Newton's law of universal gravitation
• B. Red shift of light from other galaxies
• C. The fact that every element of atomic number greater than 83 is radioactive
• D. The zeroth law of thermodynamics
• E. Mass-energy equivalence

Answer 1

Answer: (B)

Red shift of light from other galaxies

Red shift occurs due to observed elongation of wavelength of light due to Doppler effect from objects going away from the observer. Thus a red shift in the universe suggests that the objects are going away from each other, or the universe is expanding.