Split Second (14 page)

Cargill imagined Jenna Morrison
describing what had happened, reviewing that night from her perspective. If Cargill
had just heard this story without any prior knowledge of the situation, he
would want to investigate the scene of the ambush. And her PI had done exactly
that.

What else would he have done?
What else about her story could he explore?

Cargill’s eyes widened as one
interesting possibility presented itself. If the man was as good as Cargill now
believed he was, he would want to pull street camera footage of the area near
Wexler’s home in La Jolla. He’d want to see the Hostess truck. Confirm it
really was in a residential neighborhood at midnight on a Sunday. Hope to get
lucky and see a license plate or a clean shot of the driver.

Cargill had made sure this
footage had been doctored immediately, since he insisted that Q5 needed to be
fanatically thorough when they cleaned up after themselves. And then he had
forgotten all about the footage.

But the man now working for
Jenna Morrison wouldn’t know this was a dead end. So he would try to get the
video. For Cargill to find the PI in this way, the man would have had to come
up with the idea and then have the necessary connections to be able to obtain the
footage. This was unlikely, but well worth following up on.

Cargill undid his seatbelt and
walked the short distance to Joe Allen, whose eyes were now shut. He might have
just been resting, or he might be sound asleep, but Cargill couldn’t have cared
less. “Joe,” he said loudly, pausing until Allen’s eyes slid open, which they
did almost immediately.

“Yes?” mumbled Allen.

“I need you to find out if
anyone asked for street camera footage around Wexler’s home the night of the
extraction. If anyone did, I want to know who they are, and everything about
them. Everything.”

He paused, and a fiery
expression came over his face. “And Joe, it goes without saying this is
extremely urgent, and extremely confidential. I don’t want you to bring anyone
else on the team in on it.”

Allen nodded grimly. “Roger
that,” he said.

21

Jenna spent the rest of the
drive to Blake’s apartment bringing Walsh fully up to speed on all the events
that had taken place since she had returned from Chicago, just the night
before.

It was just so fantastic. Walsh
struggled to wrap his mind around it all, and the news of Nathan’s death continued
to hit him hard, as he hadn’t had any time to internalize it.

Jenna had been operating on
precious little sleep for some time now, and even though it was before nine she
was already in danger of flaming out. Blake made a pot of instant coffee, heavy
on the caffeine, and Jenna readied herself to drink the entire pot if this was
what it took to keep her awake. Given that the entire pot was meant only for
her, since neither of her companions were coffee drinkers, this was a real
possibility. Walsh elected to nurse a bottle of spring water, and their host chose
no beverage at all.

Blake printed out three copies
of Nathan’s e-mail message from Walsh’s cloud account, so they could easily
refer to it, and they each took a seat around his kitchen table.

“All right, Dan,” began Jenna
when they had settled in and had each reread the e-mail, extraordinary as it
was. “We have to assume that Nathan was on to something, and that he’s right in
every regard, agreed?”

“I think for the sake of
discussion this makes sense,” replied the physicist.

“And let’s take it to the
extreme,” said Jenna. “Let’s pretend he’d be able to send something back a full
half-second.” She whistled. “An entire half-second. Let’s go crazy. Doesn’t
really give you the chance to witness the birth of Christ or see a dinosaur,
but I guess the universe makes the rules.”

“Let’s definitely use the half-second,”
said Blake. “Trying to think in terms of . . .” He paused in mid-sentence to
consult the text of Nathan’s e-mail. “Forty-five microseconds,” he added, “is
impossible for me. It’s just too short a time to understand.” He looked at Dan
Walsh. “So I guess if a millisecond is a thousandth of a second, a microsecond
is what, a millionth of a second?”

“Exactly right,” said the
physicist. “Nathan seems absolutely certain he can push back forty-five
millionths of a second in time. And
nearly
certain he can repeat these increments to get to just under a half-second. So I
agree with Jenna, let’s assume a half-second is feasible.”

“So why would anyone care?” said
Jenna. “That’s the million-dollar question.”

Time travel stories were legion,
she knew. It was one of the most popular categories of literature ever,
especially during the last few generations. The number of stories, novels, TV
shows, and movies in which time travel was used seemed infinite. Time travel
had once been the purview of hard science fiction, but it was now not only
featured in adventures and mysteries, but in comedies, and most surprising of
all, the romance genre.

She had never really thought
about it, but what was it that made this category so versatile, so universally
popular?

The answer came to her the
moment she formulated the question. First, time travel played into fantasies
shared by every living human being. Who wouldn’t want to go back in time and
correct a mistake, right a wrong, change how things turned out? Who wouldn’t
want to have another chance to win the girl, or hit the home run? To kill
Hitler, or invest in Apple or Facebook when they were just emerging?

The possibilities for
redemption, for profit, and for revenge were endless and profound.

And then there were the
paradoxes. Each story could be written to blow minds, as
Mobius
strip pretzels lovingly constructed and twisted with glee to intrigue and
delight an audience. Twists upon twists upon twists, with intricate and
startling reveals.

Time, like gravity, was a barrier
thrown up by an unyielding universe. Mankind had always railed against both of
these barriers, forever fantasizing about their eventual defeat.

But with respect to pushing back
against the inexorable flow of time, it now seemed this wasn’t a fantasy any
longer.

“Nathan was right, of course,”
continued Jenna. “Even a half-second is far too short to make good use of. Five
minutes, sure. You could do a lot with five minutes. Win the lottery. Avert a
disaster. But half a second?”

“I know Nathan thinks time
travel will harness this immense, um . . . quintessence energy safely,” said
Blake, “but can we be sure of that? What if this really could be turned into
the ultimate bomb? Could this be what’s driving all of the interest?”

He paused. “I read a novel when
I was a kid called
The Weapon Shops of
Isher
. It was science fiction, yes, but if Nathan’s discovery doesn’t verge
on the science fictional, nothing does. In the novel, a man ends up traveling
ages and ages back through time. But for every year back he goes, he accumulates
more and more energy, until it grows to
incomprehensible
levels. Finally, when he arrives billions and billions of years in the past,
this energy is released—
explosively
.”

“I read that one, too,” said
Walsh enthusiastically. “Talk about paradoxes. If I’m remembering correctly, he
doesn’t just explode, he’s carrying so much energy he actually causes the
big bang
. So this time traveler turns
out to be responsible for nothing less than the birth of the universe.”

Blake smiled. “That’s the one,”
he said. “Anyway, I know this is taking it to extremes, but Nathan acknowledged
that he’d have to use crazy amounts of energy to pull this time travel thing
off. Enough to shred the planet. He says his calculations show all of the
energy will be used up safely, but what if he’s wrong? What if it works like in
this science fiction story?”

Jenna drained the last of her
coffee and considered this possibility further. “It’s an interesting thought,”
she said. “And I’m drawing a blank on any alternatives. But my gut tells me
this isn’t it. First, the guy at my house, the one I held off with some wine,
he told me this was potentially dangerous, but that it was
not
an explosive. He could have been lying, but for some reason I
believed him. And Nathan wouldn’t have written he was sure this was safe,
unless, well . . . unless he was sure it was safe. And would those after this really
be so zealous about something they couldn’t even be sure would happen?”

Jenna shrugged. “I’d also argue
that we already have bombs that can destroy the world. So even if time travel could
result in an even greater explosive force, so what?”

“I agree with Jenna,” said
Walsh.

Blake nodded. “I don’t see any
flaws in her reasoning myself.”

Jenna rose and poured herself
another cup of coffee. It was keeping her awake for now, but she knew that she
would pay later for this artificial boost to her wakefulness.

Meanwhile, Blake and Walsh were
lost in thought, and from their expressions neither were reaching any
epiphanies.

“Okay, so we’re dealing with a
half-second,” mumbled Blake, his hand stroking his chin absently. “
We
can’t react in any meaningful way in
this amount of time. But what about computers? For a computer, a half-second is
a huge amount of time. So say you programmed a computer to see an uptick in a
stock’s price, send this information back to itself a half-second earlier, and
put in a buy order.”

“I’m not a stock expert, Aaron,”
said Walsh, “but I’m still pretty certain this wouldn’t work. Your computer
would be fast enough to take the information from a half-second in its future
and put in a buy order, but you could never
fill
the order in time. Even if you could, second to second variations in stock prices
are minuscule. And even if you could catch these minuscule upswings, the price could
easily go down during the
next
half-second.”

Temporarily out of ideas, they
decided to read Nathan’s e-mail once again. Jenna was nearly finished with yet
another cup of liquid stimulant, but yawns were beginning to come periodically
and she knew she was ultimately fighting a losing battle.

Jenna finished rereading the e-mail
and turned to Dan Walsh. “Nathan mentions something called Hawking’s chronology
protection conjecture,” she said. “Do you know what he means by this?”

“I do,” replied Walsh. “For much
of history scientists believed time travel was absolutely impossible. But over
the last several decades, some prominent physicists from elite universities are
beginning to believe it is possible, at least theoretically.”

“Why the change of heart?” asked
Jenna.

“Well, just so you know,” replied
Walsh, “it’s been clear for quite a while that the laws of physics work
perfectly well in either time direction: forward
or
backward. In the 1940s, Richard Feynman showed that anti-matter—which
is a real thing, by the way—is identical, mathematically, to ordinary matter traveling
backward in time. He used this insight to develop a tool, called Feynman
diagrams, that revolutionized nearly every aspect of theoretical physics. So
much so that he was awarded the Nobel Prize for this work.”

“So time travel may be possible,”
said Jenna, “in
theory
. But has
anyone ever generated any experimental evidence?”

“There’s some evidence that the
future can affect the present. It’s called retrocausality. The experiments are
largely in the realm of quantum physics and are too complicated to describe.
But Yakir Aharonov and Jeff Tollaksen came up with what I think is a great way
for the layman to think about this. Basically, it is known that if you take two
radioactive atoms, absolutely identical in every conceivable way, they will
decay randomly. The first might decay immediately, while the second doesn’t
decay for an hour. But they are
identical
,
and there is no way to predict when this decay will occur. And scientists have
never identified any possible causes that would produce these effects. So Aharonov
reasoned that if the information that controls the particles’ behavior doesn’t
come from the past or present, maybe it comes from the future. Retrocausality.
Cause and effect in reverse.”

“This is all mind-blowing stuff,”
said Blake. “But one thing I’m confused about.” He stopped and grinned. “Okay,
I’m confused about
all
of it, but there
is one thing I’m
most
confused about.
You said the laws of physics work equally well backwards or forwards in time. If
this is the case, why does time seem to have a direction?”

“Good question,” said Walsh. “There
are a number of reasons. One of them you just hit on: our perception. We only ever
experience time moving in one direction. But probably the most cited reason is
something called entropy, also called the second law of thermodynamics, a
concept that has tremendous utility in physics. This principle basically states
that things tend to go from being ordered to disordered—in one time direction
only. The universe has been running down, in a single direction, since its
birth. For example, people have witnessed a crystal goblet being thrown at a
brick fireplace and shattering into a thousand pieces. The glass goes from ordered
to disordered. But it never goes the other way. No one has ever seen a thousand
pieces of glass hurled at a brick fireplace spontaneously assemble into a crystal
goblet.”

Jenna and Blake tried to digest
what they were being told, with limited success.

“This is all fascinating,” said
Jenna to the physicist. “But you were trying to answer my first question, and I
got you off on a tangent before you got there.”

“Right,” he said. “You asked
about the chronology protection conjecture. As I mentioned, serious scientists
have begun to take time travel seriously. But Kip Thorne and Stephen Hawking aren’t
buying it. Thorne says his studies suggest that all time machines would self-destruct
upon activation, perhaps the universe’s way of eliminating all those fun, head-scratching
time travel conundrums. Hawking believes that while the equations of quantum
mechanics suggest time travel is possible, the universe will refuse to allow
it, since this would be its unraveling. He half-jokingly called this the
chronology protection conjecture.
The
conjecture basically
states that the
laws of physics will conspire to prevent time travel. Which has the effect, as Hawking
puts it, of ‘Keeping the world safe for historians.’”

Jenna and Blake both smiled at
this.

“A broader definition of this
conjecture
allows
time travel,”
continued Walsh, “but only if it doesn’t create a paradox. So let’s examine a
classic paradox. Say you go back in time and kill your mother when she was a
little girl. If you did that, then how were you born? But if you were never
born, how did you kill your mother?”

Walsh took a drink from his
plastic bottle of water and let his companions ponder this for a moment. “But if
you couldn’t kill her because you were never born,” he continued, “then you
would
be born. So now you
could
kill her. It’s a circle with no
beginning or end.”

Walsh arched one eyebrow. “So
the broader version of the chronology protection conjecture would say you could
go back in time to when your mother was a little girl. But if you were intent
on
killing
her, one of two things
would happen: One, time travel would suddenly stop working for you until you
decided matricide wasn’t a good idea. Or two, it
would
work, but something would prevent you from succeeding. Has
always prevented you. Will always prevent you.”

“Believe it or not,” said Blake,
“I’ve actually read a story about Hawking’s conjecture. You jogged my memory.
It was called
The Chronology Protection
Case,
and it was in
an anthology
of detective stories. A physicist hires a detective after a fellow physicist dies
in mysterious circumstances. Before too long they discover that a large group
of physicists, who all collaborated on a paper, are dropping like flies, each dying
in freakishly unlikely ways. Eventually, the detective comes to realize it’s the
chronology projection conjecture in action. Seems the entire group was about to
publish results on time travel, and the universe was acting to protect itself. The
detective, himself, has two freak accidents that put him near death, and begins
to realize the universe is nudging him to convince the last remaining physicist
to lie about the work, and discredit it, to stay alive, ensuring time travel
never happens.”