Science fiction used to be more concerned with science.  For a period, say sometime in the mid- 1960’s to the mid-1970’s, the genre left behind the space operas of old and began to explore what might happen if scientific discoveries came to pass, how humans would interact with the world at the far reaches of science.  Authors speculated on the future but in a way that used scientific knowledge as a springboard for their speculation.

Instead of jumping from planet to planet via whatever, authors tried to look at what real faster than light travel might be like under the rules of relativity.  What would it be like to be the first humans to explore the nearest planet knowing that once your three year journey was over you’d return to a planet where more than 50 years had gone by?  No hyper-speed or warp drives or worm-hole technology, just hard physics and their effects.

Poul Anderson looks at this issue of relative time in his 1970 novel Tau Zero.  It’s this study of the effect of relative time on the human psyche that makes his novel interesting today.  While it’s still speculation, it’s still the most likely scenario for interstellar travel.  What would it, maybe what will it, be like for those travelers leaving their world behind forever?

“We are leaving more than most of us have yet understood, Charles Reymont.  It is a kind of death — followed by resurrection, perhaps, but nonetheless a death.”

For those aboard the Leonara Christine the effects or relative time will be only one of many, many problems they encounter on their journey to a planet some thirty light years from earth.  They leave knowing that when the return to earth, those they left behind will all be much older, will all have lived entire lives during their absence.  The culture they left will have already passed away, replaced by that of their grand-children’s generation.

Mr. Anderson’s characters witness what faster than light travel might be like based again on hard science:

When Leonara Christine attained a substantial fraction of light speed, its optical effects became clear to the unaided sight. Her velocity and that of the rays from a star added vectorially; the result was aberration. Except for whatever lay dead aft or ahead, the apparent position changed. Constellations grew lopsided, grew grotesque, and melted, ad their members crawled across the dark. more and more, the stars thinned out behind the ship and crowded before her.

When things go wrong, after a collision with a cloud of heavy dust particles, the Leonara Christine is forced to chart a new course, one that forces the ship to increase its speed making the effect of relative time much greater than expected.

“At Beta Virginis we would have had a thread of contact with home.  We would have though that the younger ones we left behind, given longevity treatments, were still alive.  If we must return, surely enough continuity would have persisted that we didn’t come back as utter aliens. Now though — the fact that in some sense, whether a mathematical one or not — at best, babies whom we saww in their cribs are nearing the end of life — it remids us too hard, we can never regain any trace of what we once loved.”

I found Tau Zero a very interesting read in this respect, what would it be like to know that the world you left had grown old and died in the few years you had been away, while you had hardly aged at all.   Mr. Anderson gives his book a cast of characters too large to really focus on how this affected any one person, a large cast is required to run the expedition, so his book makes the reader think more than it makes him feel, but the book is quite good none-the-less.

I’ve been reading the Gollancz SF Masterworks series for a couple of years now, along with the Fantasy Masterworks.  While I buy them for their cover art, they have made a very interesting reading list, a look back at genre history.  In the case of Tao Zero it was interesting to see just how scientific science fiction was back in 1970.