An explosive is an entropy accelerator. This is not a metaphor. The substance in the warhead sits in a metastable arrangement, its molecules held in a configuration that is not the lowest available to them but separated from the lowest by a small energetic hill. The fuse provides the kick over the hill. The reaction front then propagates through the material faster than the surrounding air can move out of its way, and what comes out the other side is the same atoms in a more relaxed configuration, with the difference released as heat and pressure. Everything the pressure encounters is shuffled, in a few hundred milliseconds, into one of the vastly many arrangements that we collectively call rubble.

A building, considered thermodynamically, is an improbable thing. The bricks in courses, the pipes in their conduits, the books on their shelves with their spines facing outward, the cutlery in its drawer with the forks separated from the spoons — each of these is a specific arrangement drawn from an astronomically large set of possible arrangements of the same matter. The set of arrangements that we would recognize as a building is small. The set of arrangements that we would recognize as rubble is enormous. This is the entire content of the second law of thermodynamics in domestic form: the building is one branch, rubble is the rest of the tree.

A building does not drift toward rubble on its own, at least not visibly, because it is maintained. The roof is patched when it leaks. The wiring is replaced when it fails. The tenants metabolize and pay rent and the rent funds the maintenance, and the building persists as a narrow-fan arrangement of matter by virtue of the continuous work that holds it there. Stop the work and it goes anyway, slowly. An abandoned apartment block in a temperate climate becomes rubble in a century or two without any help. The forward motion of the local arrangement toward the surrounding high-entropy field is guaranteed by physics; what maintenance buys is delay.

An explosion compresses the century into a moment.

This is what makes an explosive weapon, in the only sense of the phrase that physics permits, a time machine. It is a device for performing the work of time on a chosen volume of the world, at a chosen moment, faster than time would have done it on its own. The machine runs in one direction. You cannot use it to move the rubble back into a building, because the building was one specific arrangement and the rubble could have come from any of an astronomical number of possible buildings. There is no information in the rubble sufficient to reconstruct what it was. The explosion accelerates the drift the universe was performing anyway and inherits the irreversibility of that drift. To accelerate entropy locally is to advance the local temporal coordinate of a system relative to its surroundings. The apartment block is suddenly older than it was a second ago, in the only sense of older that physics recognizes: closer to thermal equilibrium with the rest of the universe, further along the path from improbable arrangement to probable one.

This is the technical content of the word destruction. The deeper content is that the building was not only a thermodynamic low-entropy state. It was also an informational low-entropy state. It held residue.

Residue is the locally improbable arrangement of matter that happens to carry meaning. A page of a notebook is a specific selection from the vast set of possible ink-distributions on cellulose, and the meaning lives in the specificity. If the ink were redistributed at random across the page, the page would weigh exactly the same and contain exactly as many ink molecules, and it would mean nothing. The meaning is the narrowness, the selection from the wide field of what could have been written. Every artifact of a human life is residue in this sense. The notebook on the desk. The letter half-finished in the drawer. The photographs in their cardboard box, unsorted, mostly of people no one in the building could any longer name but who had once been someone’s reason for keeping the photograph. The lease, the deed, the marriage certificate, the receipt from the appliance shop in 1987 that the family had kept because that was the year the father bought the first refrigerator they had ever owned and the receipt was the proof that they had ever been a household able to buy such a thing.

The thermodynamic destruction of the building and the informational destruction of the residue are the same event seen from two angles. The page of the notebook becomes one of an unimaginably large set of possible ash configurations. The receipt becomes indistinguishable from any other receipt that has ever burned. The arrangements of ink that constituted the specific record dissolve into the wide-fan of arrangements that constitute no record at all. The forward-only time machine moves not only the matter but the information forward to a state where the information no longer exists in any recoverable form. This is not a side effect of the destruction. This is what the destruction is, considered from the point of view of anyone who might later have wanted to know what the receipt said.

The casualty figures count people. They do not count residue. There is no metric for the inventory of half-said sentences that were going to be said eventually, when the grandchild was old enough, on a visit that was already being planned. There is no metric for the loose-leaf draft of a memoir that had been worked on for eleven years and had not been backed up because the writer was suspicious of clouds. There is no metric for the leather-bound family ledger that had recorded births and marriages and the prices of grain in a register that had been kept by the same family for four generations. The ledger is now in the wide-fan. So is the memoir. So is the half-said sentence, because the speaker is in the wide-fan, and the sentence existed only in him.

It is sometimes said that property loss is a lesser loss than human loss, and at the level of the individual life this is plainly true. The grandmother is more than her photographs and the photographs without her are merely photographs. But property in the inhabited sense is not what the word means in an insurance form. The deed to a house is not really a record of ownership of a structure. It is the externalized referent of a position in a web of relations: the proof that there was a family at this address, that they were the kind of family who could be at an address, that the address itself was a recognized address in a city whose municipal apparatus recognized addresses, that this whole nesting of recognitions was real enough to be written down and stamped. When the house is destroyed and the deed with it and the municipal apparatus with both, what is destroyed is not a structure but the entire scaffolding by which the family knew itself to be the kind of family it was. The grandchild in another country, forty years later, holding a photocopy of the deed that an aunt had thought to make before she left, holds a document that is fully valid as a record and fully void as an instrument. The signature is intact. The world it pointed to is not.

This is the condition of post-evidentiary life. The documents survive in scattered hands and the documents do nothing. The contracts are signed and counter-signed and the counter-signers are dead and the system that would have enforced the contracts has been replaced by a system that does not recognize the prior system’s signatures. The land registry is in a basement in a city the registrants can no longer enter. The marriage certificate is in a language the grandchildren do not read, in a script their parents could read only haltingly, in an alphabet that has been superseded twice. The forward-only time machine, when applied at scale to a population, produces a class of people who carry residue without referent. They are the custodians of records whose world has gone ahead without them, by exactly the amount that an explosion moves a building forward into its rubble-future.

The notebooks are the sharpest case because notebooks are pre-archival. A published book has already entered the duplicated trace-network; copies exist; the selection has been made and ratified by the publishing apparatus and the world has been informed that this particular narrow arrangement is one it has agreed to keep. A notebook has not. A notebook is one person’s draft of their own thinking, written for an audience that has not yet been determined, in handwriting that often only the writer can fully decode, in shorthand whose key is in the writer’s head. The forward-fan of what the notebook could become — read by descendants, cited by a biographer, found in an attic in fifty years and published, ignored entirely and thrown out by a great-grandchild who could not read the language — is wide. The backward-trace, the singular interior life of which the notebook is the only externalization, is narrow to the point of singularity. There is one copy. There has only ever been one copy. When the notebook is in the apartment and the apartment is in the path of the warhead, the entire forward-fan is amputated in the moment the warhead arrives, and the backward-trace loses its only projection into any future at all.

It is possible to feel this loss without feeling that one is committing a category error. The category error would be to set the notebook against the child and ask which is the greater loss. The notebook and the child were in the apartment together. The child was reading the notebook, or being read to from it, or had not yet learned to read but was being kept in the room where the writer worked so that the writer could keep an eye on the child and write at the same time. The two losses do not compete. They are facets of one event, which is the local acceleration of entropy in a volume of the world that had contained a low-entropy arrangement called a household, and which now contains a high-entropy arrangement that we have agreed to call by a different name only because we cannot bear to say that the household and the rubble are made of the same atoms in different configurations.

The displaced who survive the time machine carry a second condition that the dead are spared. The survivors keep moving forward at the ordinary rate while their residue has been moved forward at the accelerated rate, and the gap between the two velocities is what we mean, in plain language, by exile. The exile is in 2026 and the home is in 2200, by the local clock of entropy, even if the home and the exile both have papers that claim a more recent date. The exile cannot return because there is nothing to return to in the only sense of to that matters: the configuration of matter that was the home no longer exists, and the new configuration that occupies the same coordinates is a different country in the strict thermodynamic sense, populated by people whose own residue has begun to settle into the same volume of space and to overwrite, slowly, the traces that the exile had hoped were still there. By the time the exile is permitted to return, if permission ever comes, the overwriting is complete. The address is the same. Nothing else is.

What remains, then, is whatever the exile carried out, and whatever was duplicated elsewhere in time to be elsewhere when the time machine arrived. This is why the diaspora is so often obsessed with archives. The archive is the only known defense against the forward-only machine. To duplicate the residue, to scatter it, to make redundant copies in multiple jurisdictions, to deposit the photographs with the cousin in another country and the deeds with the lawyer in a third and the manuscript with the publisher in a fourth — this is not paranoia. This is the recognition that residue concentrated in one volume of the world is residue waiting to be thermalized, and that the only way to keep a narrow-fan arrangement narrow across long timescales is to instantiate it in many places at once, so that the entropy accelerator, when it arrives, finds only one copy to disperse.

The librarians who ran into the burning National Library at Sarajevo in 1992 understood this. So did the manuscript-smugglers of Timbuktu, who carried the libraries out in flour sacks to family houses in the desert. So did the families in every century who, on the eve of a known catastrophe, divided the photograph albums among the children so that the loss of any one child’s suitcase would not be the loss of the family’s image of itself. The practice has a long history and it has the structure of a thermodynamic argument made operational. You cannot stop the time machine. You can only place the residue in enough volumes of the world that the machine, when it arrives at any one volume, does not find all the copies.

This is also why the destruction of an apartment block is not commensurate with the loss of any one possession in it, however valuable. The apartment block is not a collection of possessions. It is a node in the duplication network. It is the volume in which one family has consented to concentrate the bulk of its residue, on the working assumption that the building will be there in the morning. The whole apparatus of domestic life — the shelf, the drawer, the box at the top of the wardrobe, the folder marked important documents — is a small archive maintained on this assumption. When the assumption fails, the archive fails with it, and what is lost is not the sum of the individual items but the integrity of the family’s record of itself. The items can be enumerated. The integrity cannot. The integrity was the property that consisted of the items being in the same place at the same time and being recoverable by the same hands.

The forward-only machine does not know any of this. It is doing only what the universe is doing anyway, slightly faster. The chemistry in the warhead is identical to the chemistry that, given a century or two of neglect, would have done the same work without any help. The acceleration is the entire content of the weapon. To accelerate is not to introduce a new kind of process but to compress a process whose direction was already fixed.

What this leaves is the strange status of the survivors and the strange status of the residue that survives in their hands. The survivors are people who have been moved forward by the machine but not all the way; the residue is the matter that was supposed to have moved forward with them but was left behind at the old coordinates, in the form of receipts and deeds and certificates whose stamps are still legible and whose worlds are gone. The survivor holds the document and the document holds the survivor in a particular relation to a time that has been accelerated past them. The document is older than it should be, by the amount of time the machine compressed; the survivor is younger than it should be, by the same amount. They no longer agree on what year it is.

This is the condition of carrying a homeland in a folder. The folder is in 1962. The carrier is in 2026. The two will not be reconciled, because the machine that separated them does not run in reverse, and the only path forward is the one in which the folder slowly thins as its contents are misread, mistranscribed, lost in moves, passed on to grandchildren who keep the folder out of piety without quite knowing what is in it, and finally placed in a drawer of a house in a country the original signatory never visited, where it will rest until that house, too, falls into its own kind of rubble, by its own kind of clock.

The atoms are conserved. The arrangement is not. The atoms do not know they were ever a notebook, or a deed, or a household, or a child. The arrangement was the only part that knew, and the arrangement is what the machine consumes.