1. Why do GPS satellites need their onboard clocks adjusted to keep accurate time?
- A) Because they lose synchronization due to solar storms
- B) Because both special and general relativity cause their clocks to tick at different rates than clocks on Earth
- C) Because their atomic clocks degrade quickly in microgravity
- D) Because the Moon’s gravity interferes with their orbit and timing
Answer: B) Because both special and general relativity cause their clocks to tick at different rates than clocks on Earth
The combination of special relativity (satellites move fast, so their clocks tick slower) and general relativity (weaker gravity at orbital altitude makes their clocks tick faster) creates a net offset that must be corrected to keep GPS accurate.
2. What does a larger amplitude in a star’s radial velocity curve usually indicate about its exoplanet?
- A) The planet is smaller and farther away from the star
- B) The planet is more massive or closer to the star
- C) The star has a stronger magnetic field
- D) The planet has a very eccentric orbit
Answer: B) The planet is more massive or closer to the star
The stronger gravitational tug of a more massive or closer planet causes the star to “wobble” more, producing a higher-amplitude radial velocity signal.
3. What did Einstein later call his “biggest blunder” in physics?
- A) Predicting that time runs slower in stronger gravity
- B) Adding the cosmological constant to force a static universe model
- C) Developing the special theory of relativity
- D) Proposing that gravity is caused by curved spacetime
Answer: B) Adding the cosmological constant to force a static universe model
Einstein introduced the cosmological constant to balance gravity and maintain a static universe. After Hubble’s discovery of expansion, he abandoned it and called it his “biggest blunder.” Ironically, the cosmological constant later resurfaced as a key part of dark energy.
4. What causes the Milky Way to appear as a band of light in the night sky?
- A) The combined light of billions of distant stars in the galactic disk
- B) Reflection of sunlight on interstellar dust
- C) Emission from nearby nebulae
- D) The theory that black holes power the expansion of the universe
Answer: A) The combined light of billions of distant stars in the galactic disk
When viewed from Earth inside the disk, the concentrated starlight of the Milky Way forms the pale band stretching across the night sky.
5. What is the cosmological principle?
- A) The idea that the universe is infinite and unchanging
- B) The assumption that the universe looks the same everywhere and in all directions on large scales
- C) The principle that galaxies only form in clusters
- D) A ring of comets orbiting the solar system
Answer: B) The assumption that the universe looks the same everywhere and in all directions on large scales
This principle underlies modern cosmology: on large scales, the universe is homogeneous (same everywhere) and isotropic (same in all directions).