Idea is very similar to John G Hemry's relatively recent & interesting story "Small Moments in Time": time travel has put an individual or two to extreme dilemma - to let large population of the other time die so own present is secure, vs jeopardizing current time by acting in a humane way. I personally find Leinster's version more interesting - he uses longer length to make it a more nuanced story.
This is the first story I've read that includes the idea of conservation of mass & energy during time travel. It fixes the total mass + energy in the universe at any moment in time. To time travel, you must exchange this with target time to keep the universe consistent! I suppose this idea alone can be used to build a good story; here it's peripheral.
Story is not always logical & sometimes challenges credulity; but it's a fast moving story, & I found it easy to ignore minor issues.
Story summary.Humans have been around on earth for millions or billions of years! And in those remote times, they were technological way ahead of current humanity. It was a disaster that wiped them out. Most of them, anyway. A few discovered time travel, & are seeking refuge in our time. This is the story of an advance party of teenage refuge seekers, & the complex reactions they generate in current time.
Disaster that struck this ancient world was the explosion of the fifth planet, along with its "two moons". It not only created the current asteroid belt between Mars & Jupiter, but also resulted in severe mountain-sized meteor bombardment of inner worlds - including earth.
They didn't get a lot of warning. Colonizing other worlds in Sol won't solve the problem - all inner worlds were being hit. We aren't told (or may be I forgot) why they didn't try interstellar colonization - probably lack of time. Only at the eleventh hour, when much of this world was dead, did a small community successfully built time travel machine - to seek refuge in a far & safe enough future.
The advance party of 4 teenagers - Fran (boy of 14), Zani (girl), Mal (girl), & Hod (boy) - will set up some equipment in current to ease transfer of rest of the party - some 2000 individuals in all. That is all that remains of this world.
But a lot goes wrong on kids arrival in present time Antarctica. Brad Soames of US station in Antarctica smashes the gate they are building to let rest of their people come. Kids blow up rest of their stuff except minor toys to ensure it doesn't fall in wrong hands. They're taken to US - to a secure military facility.
Only Soames (feeling guilty for stranding kids) & Gail Haynes (a reporter who was in US station in Antarctica at the time kids arrived) have been with kids all along, & slowly piece together the story & gain kids' confidence. Rest of US establishment has its own agenda where kids welfare doesn't count. Rest of the world is also concerned - US getting advantage of alien technology (most of the world thinks they are aliens).
A lot of adventure & confusion. Escape from military facilities... much drama. Eventually, Gail & Soames realize that only 2000 refugees are going to come - not a whole earth population. That's when they will help the kids get their people into current time. Happy ending for all concerned.
- Story has an interesting wearable communications gadget (among a lot of gadgets of time travelers). Two or more wearers can exchange all kinds of sensory perception at a distance - sort of shared virtual reality environment.
Fact sheet.First published: Amazing Science Fiction Stories, September 1959.
Download full text.
Related: All stories of Murray Leinster.
Credits: I found this story via QuasarDragon.