moment. The thought of having to clean each room for the rest of eternity as some real and present Hell came to him, and he shivered. Of course, to believe the Knight, another Nathan in another universe was doing exactly this. He returned to the book :
So too the Multiverse, Nathan. Imagine now that rather than rooms, behind each door is an entire universe. Some will be almost identical to ours, yet differ by a minuscule amount. One is almost the same as ours, yet in it a single leaf on a single tree in a dark forest by a silver lake an Autumn millennia ago does not fall; in our universe, it does.
“That's the only difference? That one leaf?” asked Nathan.
Yes. Now think of how many different tiny things could differ throughout the entirety not only of history so far, but of history to come. Then imagine the entire universe, countless billions of forests on countless billions of worlds where that leaf does not fall. That is how many rooms there are, Nathan. That is how we arrive at the figure of 10 to the power of 10,118 metres.
I repeat : all possible arrangements of matter within the specified space of our universe will exhaust themselves across that distance. Beyond, there must be repetition. That means that around that distance is an exact clone of our universe, identical in every single respect. That means an exact clone of you too, of course.
Nathan smiled.
“And you too!” he cried.
The Knight nodded.
Well noted! The book read, this is the spatial Multiverse, to crudely label it as such. There may be another, we shall call this the quantum Multiverse. Think before about how the position of particles is unknowable.
Nathan squinted.
“We can’t know exactly where they are. They’re everywhere and nowhere, all at once.”
That is correct, the next page read, to go a little further : every possible state of the particle exist all at once. When we look at it, we see only this universes' version of the particle, while a nearly infinite number of its possible states exist simultaneously in parallel universes.
Nathan struggled a little with the concept and told the Knight so. The Knight leant over and picked up a rock and tossed it to him. Nathan caught it easily and immediately threw it back. To his surprise, the Knight made no attempt to deflect the rock and it struck him cleanly in the breastplate. A page flicked across.
Think of the rooms full of universes. We inhabit the one where I chose not to catch that stone. There is a room immediately parallel where your throw was a millimetre to the left; in that room's universe the rock still hit but an infinitesimal degree away from where it landed in ours.
“So … everything that could have happened, does happen,” said Nathan.
Correct. In the rooms that closely surround ours, there are only minor variations in the probabilistic outcomes. These will still, however, be almost infinite, and they all occur simultaneously. As we move further away, we are subject to the more baroque turns of fate, which I will talk more of soon.
The Knight picked up the rock again.
Think now of our game of catch. At every single moment, universes stream away from us at light-speed, realms where every single possibility is realised, cascading bubbles into infinite-dimensional Hilbert Space. The stone is caught or is not – both these eventualities exist, and we are merely in a single version of reality among many others.
Again, a light-headedness was upon Nathan at the thought.
You shine with pure potential worlds, Nathan, other selves and lives calving off into untold dimensions every moment of your existence. It is not merely you as an individual, either, or merely every person on the Earth. Think now that every single particle in existence is within the Multiverse also. Every single variation of their possible states exists as well, since the beginning of time.
“We're back to the Gazillions of Multiverses then,” said Nathan.
Not at all, read the book. It is a number we have seen before : 10 to the power of 10,118, identical to the amount of possible universes that there could ever be given the arrangement of a finite number of particles.
Nathan found his powers of comprehension at their limit.
“I get that all the particles can be arranged in so many ways, and after a while you run out of rooms to fill,” said Nathan. “But you're talking about new universes being made if I choose to ride my bike a different way down from our hill. Where do they all go?”
The spatial Multiverse and the quantum Multiverse are the same, merely descriptions of probability, but they both exist nonetheless. Simply put, the spatial universes are extant, out there beyond, and the quantum Multiverses are enclosed within that cloud of probabilities defined by the permutations of your body's own particles. Yet I state again : They are the same, and they are finite in number, and that number is 10 to the power of 10,118.
The Knight placed his gauntlet upon the page and tapped the final sentence in apparent emphasis. Nathan saw then that each knuckle on the metal-shod fingers featured a raised pyramid of brass terminating in a blunt spike.
Over a timeframe approaching the infinite, an almost infinite number of possibilities will find realization. What is the most unlikely thing you can think of?
Reading this, the boy guffawed, for the answer was obvious: standing in a barren plain reading from a book of absolute prescience with Death and a Knight at his side was not far from it. He told the Knight this.
Indeed! The book read, yet it is a certain occurrence within the infinite timeframe. The spontaneous re-arrangement of particles in space into an exact facsimile of yourself, retaining the memories you have now, will occur without fail. It is just a matter of when and where.
“But you just said that energy … had a limit, and so did life and death,” said Nathan.
Of course. I say that there will be re-arrangement, not creation. Nothing can be destroyed or created. Whatever was will be, at least until the far distant future.
The Knight knelt. One of straps fastening his upper leg armour snapped and a hinged plate creaked away from his thigh. The gauntlet collected up a palmful of dirt. Standing, the Knight flung it to the four winds. The grit-flurry descended lightly on Nathan and he shook it from his hair.
Remember the Big Bang was merely the scattering of dust, an amount as surely finite as this. From it arose life; the potentiality of life is greater than the inherent power of the forces that seek to negate it. More than this, Nathan, is the province of philosophers.
Nathan closed his eyes in concentration and said :
“So everything that could have happened does happen somewhere, has happened and will happen again, almost forever and forever. And Death is there wherever things are alive but life is stronger. But you wouldn't want to live forever, though, 'cos that's a long time”.
The Knight nodded, then motioned for Death to approach.
A word was upon Nathan’s tongue, the same image insistently crowding his mind a moment later:
“Our frog,” he said.
At these words, Death brought up his hand and the tendrils of bone unfurled from the palm. The frog lay there and a flush of relief came upon the boy as he noted the steady pulse of its breath.
“So he will be in space forever now? Until the very end of time?”
The Knight nodded.
“I don’t want that,” Nathan said. The enormity of his words hit him and he flashed a stern look at Death. His voice shook.
“But you can’t kill him. Not ‘til I say you can.”
A new page appeared.
Remember the alternative, read the first sentence.
Tears overtook Nathan now.
“I know, I know!” he cried with a volume that surprised him.
He snuffled and wiped his nose with his sleeve. He had to look away, seeking something in the horizon that was familiar. A column of dust was at the sky’s verge, its top-wisp turning to fire where the sun lanced at it. He turned back and sternly asked Death:
“Is the frog a toy you just li
ke to torture? Like burning a bug with a magnifying glass?”
The figure gave no acknowledgment. The book whisked again.
We come to it now, Nathan. Our conversation is almost at an end.
Nathan looked at the Knight and controlled a fresh venting of tears.
“Okay,” he said, and squinted at the dust-thing again. He could not bring himself to look at the book now; his glance downward was an act of will.
Death is merely entropy; the elements that resided together briefly to constitute you dissipating, awaiting new destinies, new forms.
“Until they all fade away too, one day,” said Nathan.
Another tremor, with greater strength this time. A page flipped.
In a timeframe so vast, we need not fear it.
“Unless you lived forever.”
Nathan saw then that only a couple of leaves remained. The crab relinquished another.
Yes, it read.
“But this place, the Plain of Weapons, why would he make all this up?” said Nathan.
The final page flipped.
This work is mine alone, it read. Death wants nothing.
Nathan saw that a single sentence remained. He motioned for Death to hand the frog to him; a whisk of cold ivory against his palm along with the amphibian.
The boy recoiled and then smiled; thinking: touched by Death again.
When he looked back, the Knight was nowhere to be seen. As he sought him in all directions, the boy’s scanning eyes found that the dust-cloud was much closer now. There was nothing in the barrenness that might lend the thing a true scale, but Nathan could see it was skyscraper-high. It