Tuesday, September 10, 2019

A Labor Saving Device

     [A short story for you. Among the “classic” motifs in science fiction, time travel ranks very high. H. G. Wells’s novel The Time Machine seems to be the origin of the sub-genre. Despite their similarities, time-travel-based stories have incorporated many variations. The one below has languished in my “Someday” file for quite a while. Perhaps it will make you smile. -- FWP]

     Canfield emerged from the time vortex a bare yard from the giant brass doors of the Neutra Memorial Public Library. The effect of emergence proximity to so massive and immobile an object was to thrust him backward with sufficient force to send him sprawling onto the pavement. He quickly righted himself, clapped the dust from his coverall, looked about to assure himself that no one had noticed, and grinned at his pessimism.
     I’m getting paranoid. Who’d be on the streets at this hour?
     He approached the doors a second time. They were a formidable barrier, but Canfield’s expertise in short-displacement time travel was more than sufficient to solve them. At 0.0006 seconds per foot of spatial displacement, the four-space interval between the two points required a displacement of only 0.0036 seconds to put him safely on the other side of them. He needed barely an instant to calculate it, and an instant more to effectuate it.
     The great library was dark and deserted. Unless he were to encounter a security guard, he expected no problems locating the volume he sought. Given that the old Library of Congress numbering and indexing scheme was still in effect, of course.
     It took longer than he expected. The place was so vast, the halls so long, and the number of books in each category so large, that even after locating the Memoirs section he needed another forty-five minutes to zero in on his target. His eureka! upon finding it was louder than appropriate for a secret investigation, but after a few minutes’ nervousness he concluded that he’d done his mission no harm.
     He hadn’t expected so garish a cover. The colors were riotous and the elements bizarre, far from relevant to the volume’s presumed subject. Apparently the publisher had decided upon pulp-style shock value for a sales tool.
     No matter. It’s the content that counts.
     He’d meant to tuck the book into his backpack and trigger the displacement sequence that would return him to his proper place and time, but it occurred to him that despite the book’s seemingly perfect match to his search parameters, it might not be the one he really wanted.
     Only way to be certain is to read some of it.
     He toted the volume to a nearby carrel, seated himself carefully so as not to bruise the displacement device, and cracked the cover.


     “Yo! Wake up!”
     Canfield realized he was being prodded in the back with something hard and blunt. He came sluggishly out of his slumbers, raised his head from the carrel desk, raked his hands over his eyes, rose and turned to confront his tormentor.
     That individual was elderly, portly, uniformed, and rather conspicuously armed. He’d been prodding Canfield with the muzzle of an automatic pistol. Canfield immediately raised his hands in surrender.
     “What year?” the guard growled. His gun was pointed straight at Canfield’s chest.
     Canfield pretended confusion. “Excuse me?”
     “Knock it off, time vagrant! What’s your base year?”
     Damn. He’s got me.
     “Ah, 2061.” He peered at the handgun. “Isn’t there anything better than that yet?”
     “Don’t change the subject, asshole. Yeah, 2061 sounds right. Temporal displacement engines were invented in 2059, but they were pretty bulky back then. We banned them late in 2062. But you wouldn’t know that, would you?”
     Canfield shook his head. “Who banned them?”
     “The World Stabilization Authority, who else? Oh, right, that was something else you didn’t have yet in ’61. Never mind. They’re illegal as sin now, and you’re in open possession of one, so you’re in for a rough ride.” He glanced at the book lying open on the desk. “What the hell was so important that you risked the causal stability of the world line for it?”
     “It’s...a memoir,” Canfield murmured.
     The guard’s eyes went saucer-wide. “You displaced yourself twenty-five years forward to read your own memoirs?
     “Actually,” Canfield said, “I meant to steal it.”
     The guard’s look of incredulity deepened. “You’re a real prize. You could have made off with any of twenty-five years’ worth of news, tech developments, social studies, or what have you. Stuff you could use to make yourself a fortune. But this mattered more? What were you going to do with it? Show it to some girl you want to impress?”
     “No, sir,” Canfield muttered.
     “Then what?”
     “Well,” Canfield said, “you see, I haven’t actually written it yet.”
     The guard waited, still mystified.
     “I knew I’d write it eventually,” Canfield said, “but I haven’t, ah, done much of anything yet. So I figured I’d come forward, find a copy, bring it back to ’61, and use it as a guide to the adventures I expected to have jumping around the timeline. You know, to prepare myself, see what sort of hazards I’d face, what sort of weapons and other supplies I’d need. That way I could be sure I was ready for...well, for whatever I was going to head into.”
     “But you fell asleep over it.”
     “Yeah,” Canfield muttered. “It’s great reading. Once I started, I couldn’t put it down.”
     “But the world line it describes,” the guard said, “has just been blown to smithereens.”
     “Huh? What do you mean?”
     “You’re here, aren’t you?” The guard smirked. “You’re about to spend three years in prison for illegal temporal displacement and your life afterward well removed from your temporal origin. So you’ll never have any of the adventures in that book.”
     “There might never have been a world line in which you had them.”
     “Then who wrote it?” Canfield demanded. “And based on what?”
     “Not my problem,” the guard said. He fished a set of handcuffs from a back pocket. “Now turn around and put...what was that?”
     Canfield smiled. Mere seconds later the restabilization wave swept over the world line with a grinding roar, as if two huge planets were rubbing against one another. When it had passed the guard was nowhere to be seen.
     When he was certain the changes had completed, Canfield turned to the carrel, picked up the book, and slipped it into his backpack. He looked down at the controls on his displacement unit. They were as they had been.
     “Figures,” he murmured. “Minimum alteration for maximum causal stabilization. Just like it says in the book.”
     He pressed the toggle that triggered the return sequence. As the time vortex that would carry him back to 2061 and his basement lab formed around him, he glanced back once at the huge hall, and shrugged.
     “Now I won’t even have to write it.”


     Copyright (C) 2019 by Francis W. Porretto. All rights reserved worldwide.


Backwoods Engineer said...


Interesting story. You implied something early on that I've not seen discussed much in time-travel fiction, and that's spatio-temporal displacement. The Earth, the Solar System, and the Galaxy are constantly moving, and that's important in time travel. It might just prevent time travel.

For short time hops, like your example of going through a building's wall, we might think that the Earth's rotation speed is the dominant factor. To move 1 meter west through a building's wall at 45 degrees N latitude, you simply time-shift 3.04 milliseconds = 1/(465.1 m/S * cos(45)). Very close to the 3.6 mS you cited.

But the Earth's rotation speed of 465.1 m/S is insignificant compared to our galaxy's 631 km/sec. That's with respect to the Cosmic Microwave Background rest frame. We, and The Milky Way, are moving roughly south, toward the Great Attractor, in the constellation Triangulum Australe.

So, when you time-hop 3.04 mS from the front door, you re-emerge not inside the building, but 1.9 km (6280 ft) above it. Better pack a parachute for that trip.

It gets worse the further you go back in time. Time-hop back a year, to 10 September 2018, and you re-emerge in the hard vacuum of interplanetary space, 631*3600*24*365.25 = 19.9 BILLION km away. In the Oort Cloud. Yikes.

In order to go back in time even a little, you need a spaceship AND a time machine.

For longer temporal displacements, the 3D spatial displacement gets much, much worse. If we want to return to the time of Christ's ministry, a 1993-year temporal displacement will dump us out in the deep cold of interstellar space, 4.18 LIGHT YEARS "ahead" of the Earth's position in Jesus' time.

To see Our Lord turn water to wine, we'd need a starship AND a time machine.

If we want to go much further back in time than that, we might need to set up in intergalactic space to "catch" the Earth "when" we want to get there. Going to need more than a DeLorean, Doc Brown.

Galactic motion sort of puts a damper on time travel.

What do you think?

Francis W. Porretto said...

(chuckle) You're correct in all particulars, BE, but I didn't want to get too deeply into the complexities of multi-accelerated motion in a non-inertial frame. I was more interested in framing the key absurdities in an interesting fashion. Besides, stories are supposed to be entertaining first and foremost, and too much physics can queer the deal!

Backwoods Engineer said...

You're right, "too much physics can queer the deal." But, it is nice to be grounded in these things. I love your sci-fi (particularly the Spooner Federation series) because it contains a lot of good physics, but has gets vague on the edge of the possible.

Still, I can't help myself. One thing that *might* save time travel from the tyranny of galactic motion is rate-based time travel, which you also implied in this story.

Rather than "skip" or "jump" between times a la Back to the Future, we produce continuous temporal motion faster than the normal +1 second per second. I'm an engineer, not a physicist, but I think as long as the temporal motion isn't fast enough to cause an apparent local spatial velocity in excess of the speed of light, we continue to interact with the electric, magnetic, strong, weak, and gravitational fields that surround us. Meaning, we move in time, but we are gravitationally bound to the Earth (super important to me).

Now, we might have to travel in a precisely-defined hard vacuum to keep us from randomly bumping into the air around us and causing spontaneous nuclear fusion, but the good thing is we can take the pod with us as we move in time. Leo Frankowski's Cross-Time Engineer series used this "hard vacuum pod" idea, along with rate-based time travel.

I don't know how this works when going backward in time, but it might work like friction: there are microscopic "catches," "slides," and "jumps," but on average, the surfaces stay together.

So, what's our max temporal velocity? Spitballing, maybe it's just below the temporal rate that accelerates our galactic spatial velocity to the speed of light: Rmax = 300E3 km/sec / 631 km/sec = 475.44 seconds per second.

Call it 475 s/s. This is actually a useful rate. You could travel back a year in just over 18 hours. No worse than a long overseas airline flight. You can get back to yesterday in just over 3 minutes. Might could hold your breath that long.

With a big 475 s/s time pod, we could go see Jesus turn water into wine. We could move to Israel, and build a big time pod around an efficiency apartment containing an energy source, HVAC, sanitation, and lots of supplies. Then, we spin up the time pod, and kick back in there for 4 years, 2 months, and 10 days, reading the Bible and Francis Porretto books during the temporal journey.

Kind of long, but worth it!

Downsides: Travel time, obviously. Frankowski also wrote this into his novels: for a really long excursion in time, it takes a lot of subjective time for you to get there. Also, this method would prevent us from going through walls, because there would be a finite amount of subjective time in which we are, umm, one with the wall. Ouch. A related downside is that you will be visible to whoever is in the spatial area while you're traveling. Need camo.

Still, it's better than ending up in intergalactic space.

May the Lord continue to bless you and yours.