With the help of a small fortune and in the strictest secrecy, Dr. Julio Puertas built a time machine that ran on plutonium. Such an achievement was the culmination of a childhood dream he had never once abandoned. He studied engineering, earned a doctorate in physics, and secured a succession of well-paid positions to fund his project — all of which he resigned in order to devote more time to a machine that grew like a cosmic egg. For that was indeed its shape: an egg with one of its quadrants cut away to house a small glazed cockpit. In its depths coiled the thousands of circuits of a brain capable of deciphering the arcana of space-time.
That this enormity would end his career troubled him not in the slightest. His machine was everything. While building it, only one thing had managed to disturb him: Clara, a young woman he met in the way one meets people when one has no interest in meeting anyone — through sheer, stubborn coincidence. He justified the situation by telling himself that love and science were perfectly compatible, and that indulging occasionally in agreeable company was good for clearing a saturated mind. During the time he spent with his would-be companion, he attempted to court her with his customary clumsiness. She found him an interesting sort, nothing more, and the doctor, socially illiterate as he was, failed to notice that this interest was entirely devoid of erotic charge. Though, if truth be told, what excited the scientist far more than Clara was the progress of his machine; what he felt for the human being was a stunted, feeble fondness, utterly insufficient to quench his hunger as a temporal traveller. As the long-awaited moment drew closer, his hours of sleep and his dates dwindled to near nothing.
At last the day came when the machine was ready for its first temporal leap. Certain of his success, Dr. Puertas planned a visit to the past, though his ambition had not made him forget due caution. He had no intention of settling in ancient Rome or materialising in some unknown, perhaps inhospitable future, so his journey would carry him back a mere single hour. If something went wrong, he would still have his laboratory intact and his life more or less where he had left it. There would be time enough for grand epics — for visiting Thales of Miletus, the Neanderthals, or the galactic empires of things to come.
The experiment was scheduled for a rainy weekend. He would need to work the entire day and did not want the housekeeper, old Federica, anywhere nearby in case something out of the ordinary occurred. That woman, together with the house, was the inheritance the doctor had received from his mother. The house was perfect: isolated, silent, with a spacious basement in which to install a secret workshop. The woman was indispensable for relieving him of the burdensome domestic chores; without her, he would have had to live in filth and eat badly, something quite intolerable for his delicate constitution as the only child of a good family. Federica was, of course, strictly forbidden from descending to the basement — an order she obeyed without needing an explanation, her scientific curiosity being precisely nil. Even had she seen anything — and she had seen something — she was quite incapable of distinguishing a time machine from a very large toaster.
In the early hours of Sunday morning, everything was ready for the first journey through time in the history of the world, a memorable milestone that everyone would know about in due course. With these conceits in his head, and after several hours of calculations and revisions, Julio Puertas, dressed elegantly for the occasion, prepared to travel to the past. Three cameras recorded everything around him, while other instruments monitored every detail down to the most insignificant. The doctor, seated at the controls, waited until the sensors registered the correct reading. Then, with the haughtiness he imagined in the great heroes of history, he pressed the red button.
A roar of turbines swelled until silence cut it short in total darkness. Gradually the light returned, but around him there was only a dense white cloud clinging to the machine like a vaporous eiderdown. The scientist breathed in and waited, watchful, for it to clear — lest behind the veil, instead of his laboratory, there lay some unknown and terrifying landscape. At last, small tatters parted, and he saw before him something that left him dumbstruck: a face wearing an expression of astonishment identical to his own was watching him. He contemplated it for a while, uncertain whether he had fallen into a deep dream, but when the fog dispersed, nothing lost its solidity. Around him was the laboratory exactly as he had left it, and whoever was looking at him was as real as any one of his instruments.
He thought then that he might be living some form of out-of-body experience. He had never believed in such things, but if travelling through time was possible, why should it be impossible to see oneself from the outside? Yet he felt nothing strange to confirm this hypothesis; his body still weighed on him with the same gravity as always, and his reflection had not shed its expression of dazed bewilderment. He raised his hand and saw it; he looked at his body and patted it down. He was not, it was clear, a floating spirit. The other saw him too — saw his body, his solid, breathing person. This was confirmed when the figure asked, very slowly:
“Who are you?”
Dr. Puertas stood up and saw before him none other than Dr. Puertas himself. He then repeated, as though that prodigious mimicry were contagious even in words:
“Who are you?”
Julio Puertas, doubled and twice dressed in the suit for the occasion, gazed at himself in stupefaction. Thoughts crowded both their minds. First of all: the discovery was colossal! He had travelled to — or had arrived from — an apparently identical parallel universe! Then, with no time for celebration, they grasped the singular and anguishing novelty of their new existential situation. This presented a dizzying philosophical dilemma. Was he the same person twice, or were two people the same person once? How would he ever manage to live with himself? The figure looking back at him seemed a complete stranger. More than that — an interloper. A problem. They began to circle each other. They contemplated their own bodies as alien objects and were dismayed to discover the curvature of their spine, the undeniable progress of their incipient baldness, the flatness of their rear end, the unattractiveness of their aquiline profile, and the modest elegance of their bearing.
There was also the question of how similar their respective universes actually were. The Puertas who had arrived began firing questions, which the other refused to answer on the grounds that it was he who had the right to ask — and did so the moment he found an opening. They spent a while asking without answering each other, until it dawned on them that their knowledge must necessarily be identical. One hour’s distance did not afford much room for divergence. Then one of them moved to inspect the machine; his double stepped into his path, on the grounds that this was his invention. The reply was exact. Each was using the same argument to get rid of the other: if he was Dr. Puertas, he had built that machine, and that was his laboratory.
They argued for a while until, suddenly, as though synchronised, they fell silent. They had just changed the course of history in this universe! In all universes! At the instant a Dr. Puertas had abandoned his own to fall into this one, the twin universes had forked. The newcomer fell to brooding over his world of origin — what would happen there? Would time continue without him and have him declared missing? Or had time there paused to await his return an instant after his departure? They threw themselves at the machine: the one who had arrived needed to go back, complete the experiment, and undo this madness of being the same person twice. But the machine did not respond; its circuits were burned out and the plutonium reserve had volatilised. The repairs would take weeks or months, and the worst of it was the prospect of having to contact the Russian mafia again for more fuel — the mere thought of which froze the blood of both. Fortunately, that ordeal would have to wait; at present they had nowhere near enough money for even the smallest part of what was needed. They both knew this and, thinking alike, hit upon the same idea: one of them would work outside while the other handled the repairs. Naturally, each wanted the second task for himself and was prepared to leave the other with the burden of employment. They launched into a fresh argument until they resigned themselves to the impossibility of disagreeing with themselves, and agreed they would have to divide this new life between them. They decided to take turns at both tasks; pitiless chance would choose the order.
There was also another matter requiring urgent planning. However discreet a single Dr. Puertas might be, two would inevitably attract attention, and so they spent the rest of the night devising their routines to ensure no one would ever see them together. Particular care had to be taken with Federica, whose total lack of scientific curiosity was in inverse proportion to her appetite for worldly gossip.
Once every loose end was tied, they went to bed exhausted. To the same bed, they discovered with horror. With no energy left for further argument, a coin decided that one of them would sleep in a guest room that had been unoccupied for years at the far end of the corridor — with the non-negotiable condition that they would rotate this arrangement as well. For the afternoon they deferred the question of clothes, which would have to be divided, along with other small matters of personal hygiene.
When Federica arrived the following Monday, she noticed nothing unusual. She found Dr. Puertas in his laboratory as always. What she did not know was that Dr. Puertas had also gone out very early to a place where, not long before, he had been offered a good position. That afternoon, once Federica had left, both of them met up and explained their respective progress — which, of course, each immediately understood and endorsed, since both would have done exactly the same in each case.
They continued in this manner for some days, but the situation was exasperating for whoever drew the outside shift: not only because they disliked that work, or any work, but because that day they found themselves excluded from advances they had themselves achieved the previous day in the laboratory. Nevertheless, the alternation bred a rivalry that accelerated the repairs and improved the original prototype in ways that either one of them alone could not have achieved in so little time.
Once again they felt they were close, but many more days of work remained before the necessary funds could be raised. On weekends there was no need for precautions, so both could work at once — but they quickly realised they got in each other’s way. Whatever one wanted to do, the other wanted to do as well, and neither would accept the secondary tasks. This man, for whom solitary work was essential, would have tolerated a servant — someone submissive and without will of his own — but he could not endure himself. The only solution was to alternate Saturdays and Sundays as well. The absent Puertas, at the far end of the house, occupied himself reviewing data and reprogramming functions, but when he returned to the laboratory he would discover with indignation that the other had done exactly the same and incorporated all of it into the machine’s computer. Both saw, without saying so, the need for an outlet. Why not use the free day to clear their minds of all this fog? The answer was obvious, and both of them thought of Clara. Consumed by jealousy of himself, each Dr. Puertas kept the plan secret and arranged to meet her on a Saturday. The following day, the other Dr. Puertas, unaware of this encounter, attempted the same date — and received a response that, once he had hung up the phone, made him furious:
“All this time without seeing each other, and now you want to see me every day.”
The doctor thought fast and invented that it had been a slip, and that he had actually meant to invite her the following Saturday. Clara eventually agreed to have coffee with that peculiar, rather dull gentleman who nonetheless amused her greatly.
The quarrel that followed between the two Puertases came close to ending in physical violence. Thanks to their considerable self-control and equal lack of courage, they managed to calm their rage long enough to declare to each other, with feigned dignity, that they could not allow a sentiment as mundane as love to hinder their historic work. Naturally, neither of them had the slightest intention of giving up his meetings with Clara. And so, every Saturday, each of them claimed to have a date with her even when she was unavailable and wished to postpone it to Sunday.
“Impossible,” replied whichever Dr. Puertas knew that Sunday belonged to his antiself — a word they had coined in a moment of inspiration. “We could make it the Sunday after.”
And if Clara was unavailable then, but free the previous Saturday, the interested Puertas would twist the calendar inside out to make himself coincide with her. Through such tangles, poor Clara no longer knew whether to go on seeing this man who seemed to be losing his mind and would not stop asking her out.
As if this were not enough, Federica had long been puzzling over the strange occurrences in the house. Whenever she crossed paths with the doctor, she found him, if possible, even more surly than usual. She barely saw him eat, yet food was disappearing as though someone were consuming nearly twice as much. She did not know that every evening two people dined in the house, and two had breakfast before she arrived in the mornings. Just as two others, who were the same, would get through whatever was left in the larder over the weekend. He must be taking food to the poor, the woman thought. What a peculiar man. And what was the story with the clothes — was he changing twice a day? What new eccentricity was this? She couldn’t keep up with the shirts and underwear. She ventured to ask whether he was sleeping in two different beds on the same night; the doctor replied that he slept badly and that if he couldn’t manage in one, he moved to the other.
Being a methodical man, Dr. Puertas managed to sustain this double life without giving himself away. Perfectly synchronised, they were never once visible together. When one was outside, the other remained happily shut in his laboratory. Despite everything, they could not help a constant suspicion of their antiself, imagining him prowling the surroundings with malign intentions. And the worst of it was knowing, with mathematical certainty, that the other was thinking and feeling precisely the same. Their tense relationship came to be confined strictly to the necessities of their project, but with time, the presence of the other grew increasingly intolerable, and they began to hate him. They were perfectly conscious of this feeling, and acknowledged it honestly, not without a certain shame — how was it possible to hate oneself? They excused themselves by thinking that the other was not really him at all, but an intrusive and obsessive character who wore his clothes, slept in his bed, and pressed the same buttons he pressed. Instead of devoting their entire lives to their great project, they could now give it only one day in two. They were two demi-men who blocked, halved, and cancelled each other out.
The situation was unsustainable, and only one solution remained: the usurper had to disappear. No one would miss him, because Dr. Puertas would still be there as always. But how to do it? And then — how to dispose of a corpse that was not just any corpse, but one’s very own? The thought horrified them, and although in their nascent madness they genuinely wished the other dead, they could not bring themselves to actually do it. Faced with this predicament, both had the same idea: use the plutonium money to hire a contract killer. As soon as they had enough, they would contact the sinister mafia they already knew — before their rival did. Because they knew the other was planning exactly the same thing, a certainty so macabre that it ultimately unhinged them both.
They began to spy on each other. When one went out, the other, in an act quite unimaginable for a lone Dr. Puertas, abandoned his laboratory and followed him silently. He wanted to know whether he was really going to work or meeting someone suspicious. With the same fear, they compulsively monitored their bank accounts, lest the other find some trick to circumvent the double password securing them. With so much surveillance, they neglected their duties and lost their job. The company breathed a collective sigh of relief to be rid of the man who seemed to inhabit a different dimension and had lately taken to disappearing with the most outlandish excuses.
Unhinged by a profound anguish, the two Puertases began to overlap in ways intolerable to them and increasingly conspicuous to others. With growing frequency, Federica would see one of them go out and then the other emerge shortly after, and she wondered in bewilderment what that man was up to — coming back the moment after he left, slipping in through the back door without a sound and changing his clothes. She avoided seeing them together only by sheer luck. The person who did enjoy that privilege was precisely the one with the least credibility: a retired old man fond of wine who strolled through the park facing the house. He swore he had seen two figures identical to the late Mrs. Puertas’s son arguing in low voices behind a hedge. When people retorted that the alcohol was making him see double, he would bristle and insist he had not been drinking at that moment.
“They were two different but identical people, and they were wearing different clothes. I always assumed he was an only child, but it turns out there are twins,” he concluded with absolute conviction.
Nobody believed him. They laughed at him and at the vinous delusions of his mouldering brain — and then used the occasion to gossip about the doctor, who had gone from being a mysterious figure locked away in his castle to roaming the neighbourhood in the strangest fashion. One would see him going up and coming down, first in a white shirt with blue stripes, then in a blue shirt with white stripes. Where was he going and where was he coming from? The two Puertases devised a thousand and one strategies to keep the other away from the laboratory, the house, and Clara — in short, from their lives. Subtle traps that obliged the enemy to absent himself and left the coast clear for doing and undoing in the workshop, pestering poor Clara, or refining a murder plan of quite picturesque ambition.
Clara tired of him very quickly. The man who had been interesting had definitively become insufferable. First she asked him politely to stop seeing her; then, with carefully chosen words, she urged him to stop calling. Dr. Puertas, consumed by the obsession of feeling invaded, experienced a singular jealousy that he would surely never have felt had his rival been anyone else. He would have found it perfectly natural for the girl to fall in love with some insipid civil servant — someone with a guaranteed salary and ordinary tastes. He considered himself unreachable, immiscible with the rest of humanity. His only rival was himself, and that was precisely the problem: a self that competed with him and was usurping his life.
The nerves and tension, combined with the already anxious constitutions of both doctors, had taken their toll on their habits and their figures. They were incapable of concentrating on anything, and at the slightest provocation they imagined the other spying from behind the curtains. They could not sleep and spent their days rigid with tension, their necks hunched and their shoulders braced. The same posture that had given them a slight stoop was now, further exaggerated, digging into their cervical vertebrae. The pain rose into their heads and prevented them from thinking with the required detachment. They began to stuff themselves with pills — first analgesics, then some tablets their mother used to take for her nerves. On this diet, the brilliantly intelligent doctor traded judgment for derangement. Federica could not stop marvelling at the new habits of her employer. The methodical man of ironclad routines had become a scattered vagabond drifting around the house. From the outside, it appeared that some illness was tormenting him, but she dared say nothing. The only thing she could think to do was to call the only known relative of the doctor: a great-aunt who lived in Logroño. The woman reassured the housekeeper and promised she would call her great-nephew.
“I’m sure it’s nothing — you know what he’s like, he’s always been a strange one,” she said, concealing her considerable reluctance to make contact.
Being a dutiful woman, she called the doctor on a Friday afternoon. And he, being busy pursuing and hiding from himself, did not answer. Another time, the great-aunt told herself, not knowing that there would be no other opportunities.
The following morning, emerging from their opaque dreams at the exact same hour and second, both doctors flung themselves toward the laboratory. One of them — for chance always favours someone — had the luck not to trip on the staircase leading down to the basement. With this advantage, he reached the door and turned the bolt. The other, bruised from his fall, took a while to get up and find his key in his pocket. When he tried to open the door, he found it barred. Hysterical, he began hammering at it uselessly, terrified that his machine was about to be destroyed. Both had by now lost any image of themselves in the face of their identical: they saw only an enemy, an invader to be exterminated.
And so, while one Dr. Puertas hurried in the laboratory to transfer priceless data onto an encrypted device for his exclusive use, the other arrived with an iron crowbar, ready to force the entrance — barely secured with a plank hastily wedged in place. Once inside, without any clear awareness of what he was doing, he raised the bar and threatened his antiself. They chased each other around the machine in a scene worthy of a comedy film, until the pursued Puertas managed to slip away and ran upstairs. The other, of course, knew exactly where he was headed, because he had had the same idea himself.
Once in the sitting room, they threw themselves at a display cabinet. There, resting within it, was their grandfather’s old shotgun. They had never touched it. As children, when they had wanted to, their mother had forbidden it, and as adults they had lost interest. But now, suddenly, the memory of the only weapon in the house had come rushing back.
Again, the race had a winner. The loser, weighed down by his heavy iron bar, arrived to find the ornate hunting gun already raised. They froze. One at the sight of the barrel aimed at him, the other at the awkwardness of his own improvised and clumsy marksman’s pose. Would he be capable of firing?
“It isn’t loaded, you idiot!” shouted the one being aimed at.
But neither could be certain. Their grandfather, whom they had barely known, had been an unpredictable and ill-tempered man, quite capable of having died with the gun loaded. And his daughter, who revered her father, would never have poked around in that object, nor allowed anyone else to. And if it was loaded — would it still work?
There was no going back, and no time to think. Neither was prepared to yield. The doctor who was being aimed at, in a flash of bravery, lunged forward with his iron bar raised and the cry of “Give me back my life!” And the other, by reflex, pulled the trigger.
It was not loaded. The shock of the silence, where a thunderclap had been expected, struck the would-be victim down: he felt no bullet, but a searing blow in his chest that paralysed his arm and made him drop the bar. On the floor, he writhed with the sharp pain of a heart attack. The other, his own heart at full gallop, had lost all grasp of the situation; seeing him fall, he thought he had truly shot him. This impression, combined with the sight of himself dying — for he now understood that the other was him — compelled him to mirror his fate, heart for heart.
They died at the same instant. What we do not know is whether each crossed his own door into the beyond, or whether both crossed the same one.
The following Monday, Federica found the bodies. The shock was such that she very nearly followed them across. She did not pause to look at who was lying dead beside the master of the house — one of the corpses was face down, the other face up — and ran out screaming that Dr. Puertas was dead and that a murderer, also dead, had killed him.
When the police and the examining magistrate finally arrived, they were confronted with a scene of the most unusual kind. Two identical men had lost their lives without any apparent violence. Beside them, an iron crowbar and a disabled shotgun indicated that there had been some form of confrontation, but nothing was broken.
On examining the laboratory, they were astonished by the sheer sophistication of the electronics — and above all by that futuristic vehicle that looked as though it had been taken from a film. At that moment, no one was in a position to venture any hypothesis. In time, the affair became more baffling still. Of the two dead men, it was impossible to determine which was the real Julio Puertas, or where the other had come from. Both were identical freckle to freckle, hair to hair, cell to cell. They shared DNA and fingerprints. The inexplicable resemblance was so complete that the case became unique, studied by every forensic scientist and specialist in the field — as well as by the “paranormal scientists” who dissected their various theories on their late-night television programmes.
“And that strange machine,” one of them was saying, with an expression of contrived mystery, “that device packed with technology so inconceivable that no engineer of our day has been able to decipher it — could it not perhaps be a kind of time machine in which a second Dr. Puertas arrived, possibly, from a universe identical to our own?”
No one in our universe was able to offer any certainty on this strange case. Nor in that other universe from which, with the utmost discretion, Dr. Puertas one day disappeared without a trace. There, they did not even ask about the nature of a machine which, deprived of the publicity of a murder, ended up forgotten in a locked basement.