Why can't we see past the cosmological horizon?
A) Every galaxy in the entire universe (not just the observable universe) exists within the cosmological horizon, so there's nothing to see beyond it.
B) It's impossible to look back to a time before the universe was born.
C) We do not have telescopes big enough.
D) The cosmological horizon is infinitely far away, and we can't see to infinity.
B) It's impossible to look back to a time before the universe was born.
You might also like to view...
In which of these processes is an element transformed into a completely different element?
A) alpha decay B) beta decay C) both of these D) none of the above
To estimate the central temperature of the Sun, scientists ________
A) use hot gas to create a small Sun in a laboratory B) send probes to measure the temperature C) monitor changes in Earth's atmosphere D) use computer models to predict interior conditions
A frictionless pendulum clock on the surface of the earth has a period of 1.00 s. On a distant planet, the length of the pendulum must be shortened slightly to have a period of 1.00 s
What is true about the acceleration due to gravity on the distant planet? A) The gravitational acceleration on the planet is slightly greater than g. B) The gravitational acceleration on the planet is slightly less than g. C) The gravitational acceleration on the planet is equal to g. D) We cannot tell because we do not know the mass of the pendulum.
A 1.6-kg block slides down a plane (inclined at 25° with the horizontal) at a constant speed of 2.0 m/s. At what rate is the frictional force changing the mechanical energy of the block?
a. +28 W b. +13 W c. ?13 W d. ?28 W e. +6.5 W