This was Robert Silverberg's first short story collection, originally published in 1962 as the second half of an Ace Double, paired with Silverberg's novel The Seed of Earth. It was later published as an Ace standalone paperback in 1977, with a hardcover edition eventually coming from Dobson in 1979 and a Tor paperback reprint in 1986.
This marks the only appearance of the story "Hopper" in a Robert Silverberg collection, although it was also anthologized in 1980 in Science Fiction Origins, edited by Martin H. Greenberg and William F. Nolan.
Here are my individual story reviews:
"Blaze of Glory" (1957) -- A hot-headed communications officer sacrifices himself to save his ship, but was it heroism or murder?
"Warm Man" (1957) -- An empath comes to a small New York suburb. A smart social satire that shows the author's developing range. Reminded me of Harlan Ellison's "Try a Dull Knife," only more coherent and accessible.
"The Songs of Summer" (1955) -- A time traveler from New York, 1956, accidentally winds up in the 35th century, where he tries to bring back modern civilization to an agrarian society. Includes many now-familiar s/f tropes such as telepathy, group-mind or hive intelligence, and the idea we could be living inside a world of our own imagination. This was the author's first attempt at using multiple narrators and points of view within a single story.
"Slaves of the Star Giants" (1956) -- Lloyd Harkins is transported to a far future when civilization has collapsed. Small mutated humans live underground in isolation. Ancient robots left over from the Time of Cities still roam the jungles but no longer serve any useful function. Small human tribes aboveground are used for social experiments by a race of aliens known as Star Giants. Harkins hatches a deadly plan to find the Brain that can reprogram the robots in order to wage war against the alien interlopers.
"Hopper" (1954) -- Earth is overcrowded and suffering from widespread air pollution. Someone has invented time travel and is illegally sending poor people back to the 20th century. Corrupt police officer Quellen is in a quandary -- If he apprehends the criminal, he may alter the past (and who knows what the consequence will be?), but if he lets the criminal go free, the inevitable tide of history will result in the unsustainable reality in which he is living. This was one of Silverberg's first four published stories. It has a great premise, but he clearly does not have the skill to carry it through. Quellen eventually decides to escape into the past himself, only to make sure is he is not arrested for maintaining an off-the-books residence in Africa that is forbidden by law. Later expanded into the 1967 novel The Time Hoppers.