There is a theory that gravity could pull galaxies back together, causing a reverse big bang. Which observation makes this theory less likely than the idea that the universe may continue to expand?
A. Background radiation is present.
B. Galaxies exist outside of the Milky Way.
C. The expansion of the universe is accelerating.
D. Gas giants form farther from the Sun, where temperatures are cooler.

Consider the growth of a 20-nm-diameter silicon nanowire onto a silicon wafer. the temperature of the wafer surface is maintained at 2400 k. assume the thermal conductivity of the silicon nanowire is 20 wm-1k-1 and all its surfaces including the tip are subjected to convection heat transfer with the coefficient h = 1×105 wm-2k-1 and t∞ = 8000 k. when the nanowire grows to l = 300 nm, what is the temperature of the nanowire tip (t (x =