Pathspace: The Space of Paths (12 page)

But Drew was still too young to fill his
place. How would his mother manage without him?

He shook his head and turned toward the
window. Out there, in the slowly decaying streets of the city,
where the asphalt of ages baked and cracked under a lingering
Summer that, concentrated by reflection from the brooding scrapers,
would not yield to Autumn, ordinary people were going about their
lives with the certainty of their daily routines.

But his mind resisted
routines in this place. Oh, he was diligent in his practice, but
not in a regularized way. Something in him balked at the idea of
marching off the hours the same way on every day, this now and the
other later. Like a plow-horse tilling a field, with no will of its
own.
Yes, I will practice. I'll learn what I must learn
to set my own course.

On impulse, he swiveled to
his left and reached out to pluck a book from the hundreds Xander
lines his walls with.
Questions For
Posterity
, by Hugh Stevenson, was a volume
about the last days of the Ancients, after the Tourists had
departed, their database of Earth's genome sequences complete. It
was after the adoption of the Gifts as cornerstones of a more
efficient infrastructure, but before the collapse of that very
infrastructure, due to what Xander had called “the lack of
technical support for the Gifts.”

“
...and so questions
remain long after the objects of those questions have gone. Will
the Tourists find actual uses for the genetic sequences they
bartered for? Will we ever come to grips with an understanding of
how the Gifts actually work? Sometimes, this reporter finds it
doubtful. Their operation cannot be doubted, yet contradicts what
we thought we knew about the universe. A friend of mine at MIT
assures me that there is no such thing as something for nothing.
Energy cannot be created or destroyed, merely converted to other
forms such as matter, or concentrated or dispersed.

“
But the Gifts of the
Tourists deft such reasoning. They have no moving parts, no
circuitry, and require no power input. Where is the catch? A
swizzle can impart motion to fluids and even pump them uphill:
hydroelectric dams no longer require a river for their source of
water, merely a lake and a big swizzle to push the water back up
after it has fallen and driven the dynamo. But this gives free
electricity! It is literally something for nothing.

“
Similarly, the everflames
that now smelt our ore require no fuel. So where does the heat come
from? Is somewhere else cooling off to balance the equations? Are
we pulling heat out of the magma inside the Earth? Or from the Sun
or other stars?”

He closed the book. Its questions went
unanswered, most of them. But at least he now knew the “catch” the
Hugh was referring to – the price to be paid for the use of the
Gifts in Earth's . For gifts without knowledge, the price had been
the loss of our own wisdom.

It had been hard form him to accept how
easily it had happened. He remembered his last argument with the
wizard about it. “The Ancients were not fools. The couldn't have
been fools, when they accomplished so much before the Tourists
arrived. So why didn't they predict the consequences? More to the
point, why didn't the Tourists?”

Xander had shrugged, as he often did to such
questions. But he tried to explain it. “Imagine you are an ancient
explorer in a sailing ship and you meet natives on an island who
use stone axes to cut down trees.”

Here Les interrupted. “How do you make an
axe out of stone? Smiths use iron for that.”

“
You take a couple of hard
rocks and use one to chip away at the other one, breaking off chips
along one or both sides of one end to make a crude edge, then you
tie the sharp rock to the end of a stick. But now you, the explorer
arrive and trade the natives pre-made axes with steel blades. What
happens?”

“
They realize the metal
axes are better, and stop shipping stone for axes.”

“
And
eventually?”

“
They forget how to make
stone axes.” He thought about it. “And after you sail away, the
metal axes eventually rust away and are useless. Now they're back
to square one. They have to learn how to make stone axes all over
again, because they didn't think that skill was important enough to
pass on to their children.”

“
Exactly. And so it
happens.”

“
But they must have known
it would! Surely they'd seen that happen to islanders, just as you
described! Didn't they realize the same thing could happen to
them?”

Xander had shrugged again. “Maybe some did.”
he glanced at the window. “Maybe somewhere out there people are
still making generators and internal combustion machines. God help
us if we run into them, because they'll conquer us easily.”

Lester put the book back
on the shelf where he found it.
But if we develop an
effective technology first,
he
thought,
we'll be the ones doing the conquering.
And that's what Xander is hoping to set in
motion. A hybrid technology, like the Ancients adopted, but this
time with technicians who can keep it going: wizards.

And I can have a place in this plan if I
seize the opportunity.

Right. He sat himself down again and devoted
himself to the apple. There was something missing in his attempts.
He had been imagining the photons as moving around the apple
instead of hitting it, and that resulted in a partial transparency.
But he must be doing it wrong. He must be barking up the wrong
tree, or heading down the wrong path...

Suddenly it came to him.
He had been thinking about the photons, not about the
pathspace
. Maybe that was his mistake.
Instead of imagining all the bits of light zooming around the apple
and not hitting it, he should be imagining the path as a
thing-in-itself, like the road through Inverness, that existed all
the time, not merely when a coach was rolling down it.

He had to lay out the road
in his mind, and then the light would follow it. Concentrate on the
road, not the coaches. The
pathspace
. The space of paths.

This time he imagined a rectangular region
on his face. Then he moved the rectangle toward the apple, tracing
out innumerable paths in the intervening space that glowed in his
mind's eye. As his rectangle neared the apply, he split is like
opening window curtains and swept the sides around the apple,
tracing out glowing paths around it that remained when the
rectangle had passed it.

And the apple disappeared!
He slid back his chair and got up, moving slowly lest he break his
concentration. The apple stayed gone. He let his mind relax, and
the apple was
still
gone. The
pathspace configuration he had managed was persisting!

He experimented, walking
around the table. When he reached a position a quarter of the way
around the table the apple reappeared.
Damn it!
He moved back to his chair, and it disappeared
again.
What?

Walking completely around the table, he saw
that the apple was invisible from his original position and
directly across from it. Evidently the pathspace was bidirectional.
Once he had established the pattern, it hid the apple along that
line of sight from either side. But not sideways to it. All right,
so he needed more practice. But he was finally getting the hang of
it. What he had now would be pretty good, if he were hiding in a
corner of a room, or directly in front of someone. It was better
than nothing.

Now the next questions were: how long would
it last, and how could he stop it if he wanted the apple completely
visible again, from all sides?

Hmm. First he tried to
make the invisibility complete. And he succeeded, but only in a
tedious way, by using eight patches of
pathspace
, deflecting around the apple
from the eight major directions of the compass. This worked. There
was enough overlap that the apple was no invisible from all
directions around the table.

But not from all directions in space, as he
found by leaning over the table and looking down. So he eliminated
that too, but visualizing a circular patch of pathspace
cross-section descending on the apple from above and splitting
around it.

He frowned at all the work involved,
doubting that in an emergency he would have the time for so
elaborate an imagining. All those patches took too long. But at
least he was finally getting complete invisibility.

Now for the next step. To the right of the
window a door opened into an inner room. He had not discovered this
the first night, because he'd fallen asleep on the wizard's couch.
But there had been ample time after that to explore the confines of
his quarters. And one of the things he found, when he did so, was
that the inner room contained a full-length mirror, the first he
had ever seen. At first he was astonished at the luxury, then
amused at Xander's vanity.

Now he blushed to remember those mistakes.
By now he knew Xander didn't care much how he looked. The mirror
was for invisibility practice.

When the wizard told him this, he almost
laughed in his face. “You don't need a mirror! You already told me
that when your shield is in place, you're left in darkness because
the light can't reach your eyes anymore.”

“
Yes,” Xander replied.
“But what if I wanted to shield someone
else
, behind me – and without taking my
eyes off the enemy in front of me? How would I practice
that?”

Abashed, Les had to admit it made perfect
sense. Once more he reminded himself never to ridicule something
the wizard told him without thinking a lot first.

He stood in front of the mirror now,
concentrating. First things first. This time he tried to imagine
eight man-sized rectangles of pathspace converging on his position,
only to split around him and continue on.

As he had expected, his first attempt at
this was only partially successful. The view in front of him went
black, as did the view to the right. But to his left light still
poured in. The same applied to the view behind him.

He let the hot wave of anger wash over him
and pass on. There was no use holding onto it. Then he spent the
next hour or so practicing each of the eight cardinal directions
oft the compass by itself, until he satisfied himself that he could
do all of them equally well.

By this time he was wet with perspiration –
and starving. He took a break and visited the bathroom to get some
cold water. He was rather proud of the fact that he'd worked out
how to control the spigots on the sink all by himself, once he'd
gotten used to the fact that one of them eventually produced hot
water. There must be an everflame rigged to heat a water tank
somewhere up near the roof, he reasoned.

After he managed to stop sweating, he opened
Xander's coldbox (the old rascal had all the conveniences of an Inn
here – except a stove, and he needed none since he had at least one
portable everflame and they delivered meals to his door anyway,
presumably to keep him from wandering) and found some cooked
mutton. Did they raise sheep on one more more floors of the
scraper? He had to admit that the Governor's palace was even better
than the castles in the storybooks. It was as if someone had taken
an entire village, complete with some farmland, and stacked it up
vertically like a pile of pancakes. And all you had to defend was
the ground floor.

Back to the mirror. This time he tried
imagining the patches in pairs, beginning with his left and right
sides. After he could do any of the four opposing pairs in his
eight directions, he tried to do two pair at once, left-right and
forward-backward.

His first attempt at this was pretty good.
Darkness on four sides, and only slivers of light on the diagonals.
He kept at it, alternating between the regular and the diagonal
four-axis configurations for the next hour.

Another break to rinse off
sweat and grab a snack followed this. Then he went back to trying
all eight directions at once. Right away he had problems. It seemed
that he had real difficulties tracing out of all that
pathspace
at once. He wasn't exactly sure
why. It had not seemed that hard to do one, two or even four
directions, but he just couldn't seem to get all eight.

Then he had an inspiration, and split it
into two groups of four, the regular four and the diagonal four,
and doing it in two steps instead of all at once. This succeeded!
It was slower than doing only one, two, or four, but faster than
doing all eight one at a time.

Now for the hard part. It was time to try
something Xander hadn't mentioned: trying to stay shielded while
walking. He wasn't sure how to do this, and wanted to try to work
it out on his own to impress Xander.

First he backed up all the way to the wall
opposite the mirror, making sure the straight line path to the
mirror was free of clutter he might otherwise trip over, when he
couldn't see in the forward direction. Then he concentrated and
formed a forward shield, leaving the other seven directions
visible.

Now here was the trick he
hadn't figured out. How could he make the shield move forward with
him – so that it was always blocking him from view as he proceeded
toward the mirror? He was a little nervous about what it might do
to him to walk right through the shield. How would the
pathspace
affect the matter of his
body?

There was no way to tell. Finally he gritted
his teeth, screwed up his courage, and extended the tip of one
pinkie through the shield. Apart from a slight tingling, he felt
nothing, and it didn't chop off the finger as he had feared it
might. Right.