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Is time travel possible? An Argentine physicist explains how


Gustavo Romero, director of the Argentine Institute of Radio Astronomy, speaks from science, but also from the intersections with cinema and literature.

There are too many (endless?) ways to start this note: better do it at the beginning (if such a thing exists).

Every word of Dr.

Gustavo Esteban Romero

, Argentine physicist, UNLP professor and CONICET researcher, arouses questions.

He received


at the offices of the

Argentine Institute of Radio Astronomy

(IAR) that he directs, in the Pereyra Iraola Park.

For him,

science and literature

are parallel universes.

In conversation, he can explain how a movie written by one scientist led another to refine wormhole theory, and why time machines are scientifically viable.

In the sky, the stars.

In fiction and on Earth, too.

Author of almost half a thousand academic articles, Romero published different popular books: among them,

Is it possible to travel in time?

, in 2008. The following year,

Stephen Hawking

was promoting a dinner party, inviting "time travelers" to an elegant Cambridge ballroom.

Brilliant, provocative and a bit of

a showman

, he concluded that the lack of attendance served as proof that such people did not exist.

Stephen Hawking's invitation to "time travelers".

No one went to his dinner.

For him, proof that such people did not exist.

Kip Thorne, Nobel Prize in Physics and adviser to major film productions, responded.

Many have asked the same question: if it is possible

to move through space-time

, why aren't there tourists, souvenir buyers, historians, archaeologists, fugitives, criminals or politicians from the future in sight?

Will they be disguise geniuses?

Romero says that Kip Thorne, winner of a

Nobel Prize in Physics 

and adviser on films like




, decided to refute Hawking.

And he proved mathematically that, if it were possible to build a time machine,

it couldn't be used to travel back to a time before his creation


The reason why no one sat down at the elegant table to eat would have been—in Creole—that a time machine had not yet been built.

The answer gave rise to the so-called "Hawking paradox".

Who said calculations weren't fun?

Talks about the origin of the universe, time travel, philosophy and literature, without losing a smile.

Photo: Constanza Niscovolos (Clarin).

Once Upon a time

Did time travel fantasies come first to literature or physics?

Romero assures that the writers were precursors.

The context was fundamental: the

Industrial Revolution

and the optimistic imaginary of progress made it possible to visualize machines capable of anything.

If there were already stories in which some hallucinogen, an unusual event or a blow to the head took the characters to other dates and latitudes (just remember the novel A Yankee

in the Court of King Arthur

, by Mark Twain), it was the Catalan Enrique Gaspar y Rimbau the first to devise a device (the "


") to move in time using electricity.

"The idea is crazy, but pioneering, since it was supported by technology," the professor develops.

Then came the classics: the novels

The Chronic Argonauts


The Time Machine

, by

HG Wells

, published in 1888 and 1895, respectively.

In the first, the plot dealt with trips to the past;

in the second, towards the future.

Although authors of the stature of Wells were visionaries, the traces of the 19th century are indelible.

They are reflected in the levers, wheels and gears,


(forgive the redundancy) in a century of nanochips and robotics.

As Romero indicates, both in fiction and —especially— in science, "today we think of

taking advantage of certain natural phenomena, in order to be able to manipulate space and time at convenience


Timeless readings: literary recommendations from a physicist

In 1962's

The Man in the High Castle


Philip K. Dick

launched into a uchronia—or a reconstruction of history on hypothetical data—where the Axis forces won World War II.

The book became a success and was brought to the small screen by Amazon Studios.

Counterfactual hypotheses also feed into academic


, but they don't stop there.

The "what would have been" crosses the mind of any mortal.

Who did not think, before going to bed, what his life would be like if he had made other decisions?

What if that accident hadn't happened?

Or, forward, if he dropped everything and started from scratch.

Television adaptation of "The Man in the High Castle", a book by the renowned science fiction author Philip Dick.

The director of the IAR is convinced that

temporal perplexities

have always been with us.

The notion that things happen in an irreversible way causes existential crises.

At least, that's what he felt since he was a boy.

To solve the mess, he started with the library and the TV, and ended up in the cloisters.

He became a relativistic physicist.

In other words, he studies space and time, using the tools of general relativity.

But he did not lose his taste for the classics like

Isaac Asimov


Ray Bradbury


Arthur C. Clarke

(the "ABC"). 

He particularly recommends Robert Heinlein

's short stories

 "By Your Own Means" (1941) and "All You Zombies" (1958) and invites you to see


, the film starring Ethan Hawke that shows a sort of self-entity generated in a loop giant storm.

That same concept reappears in the story "El serrucho", by

Alfred E. van Vogt.

There, a character travels into the past, further and further, until finally his own journey ends up causing a release of energy, which produces the Big Bang and the entire universe (including himself).

Ok, enough



The incredible thing is that the American physicist Richard Gott III wrote an article for the scientific journal

Physical Review

, with a very similar cosmological model.

That is,

a self-generated universe

, which, at the beginning of its expansion, had a region where time travel was possible.

In this sense, for the scientist,

the cause of the universe would not be in the past, but in the future.

Light, Camera, Action: Hollywood and a Scientific Revolution

Carl Sagan

, NASA adviser, popularizer, and keeper of the golden records —a sort of time capsules of terrestrial culture— that accompanied the Voyager space probes, wrote the novel Contact in



As Romero points out, the event was not another event in the astrophysicist's long career, nor a mere sales and box office success (when it was made into a film by Robert Zemeckis), but rather gave a boost to the development of travel science

. in the time.

Contact, the novel by astrophysicist and popularizer Carl Sagan that had an impact on three fields: the literary, the cinematographic (directed by Robert Zemeckis) and physics, thanks to the debates with his friend Kip Thorne, who developed the theory of holes of a worm to "save the plot",

For the plot to work, the protagonist had to travel from one star to another, almost instantly.

For that, Sagan decided to throw her into a

black hole.

"He was not a relativistic physicist, but a planetary physicist, so he decided to consult his friend

Kip Thorne about him

. He replied that this was not realistic, but he did not sit idly by."

Romero is enthusiastic about the story.

Thorne wanted to do something to salvage the argument: he forayed into a solution to Einstein's equations that would enable that "shortcut."

He developed nothing less than


The Cosmos


took it, and Thorne

published his findings in the

American Journal of Physics

, causing a sensation.

Kip Thorne, one of the great physicists of his generation and incurable movie buff.

In the picture, he laughs and talks on the phone, having won the Nobel Prize in Physics for his discovery of gravitational waves, along with Barry Barish and Rainer Weiss.

Photo: Ringo Chiu (Reuters).

During a talk on this topic, a colleague suggested to Thorne that, following his reasoning, not only two points in space could be connected, but also in


After reviewing the hypothesis, in 1989, the researcher sent


first article on time travel to the prestigious scientific journal

Physical Review Letters .

There he discussed a specific design of

"time machines"

, based on Einstein's equations, through wormholes.

He forever earned a

star on the scientists' walk of fame.

"Thorne proposed a space-time that does not have a flat topology, but one that can be bent. Thus, one can enter one side and exit the other, almost instantaneously, connecting two points far apart in space-time, both both for the past and for the future", details the interviewee.


do they exist in reality?

There are those who consider the possibility that, as with black holes, the universe came with them from its origin.

This has not been established (it was even very difficult to verify the presence of black holes, about which Robert Oppenheimer began to theorize in 1939).

Artist's recreation of the process by which a black hole eats a star.

Photo: Martin Kornmesser (ESO, via The New York Times).

Another window opens


Could they be made?

"That is the other big question. In principle, it would be necessary to manipulate what Thorne called 'exotic matter', which does not produce gravitational attraction, but rather repulsion."

This type of matter exists, because it has been measured.

For example, at the


level .

The universe itself, as a whole, seems to be expanding at an accelerating rate, and the reason seems to be because it is dominated by energy of negative density.


can you operate on this matter?

It is not clear.

"To build a wormhole that is large enough for a person to go through, a very large amount of this exotic matter would be needed. Approximately one solar mass," continues Romero.

The human would not be able to undertake such a task.

Could a more advanced civilization do it?

movies through the telescope

Are there movies that come close to the parameters of a scientist?

Romero lists a few.


 (the original);

Twelve Monkeys

, directed by Terry Gilliam and starring Bruce Willis;

the Spanish



and, finally,

The Time Tunnel,

the series he watched when he was a child that led him towards Physics.

And what about the favorite of sci-fi fans and moviegoers in general, the

Back to the Future

trilogy ?

The doctor understands that attachment to science was not the goal of director Robert Zemeckis.

He accepts that they are classics that he likes.

Like any spectator, you can sit down on a Sunday to eat popcorn and enjoy the good performances, the effects achieved and an

attractive script.

Although he mentions —how could it be otherwise— that the Russian physicist Igor Nóvikov, a friend of Kip Thorne, showed that the requirement for time travel is that the principle

of self-consistency

be respected .

This implies that any local solution to the equations of physics has to be globally consistent.

The universe exists as a whole and nothing that an individual does can produce a contradiction in the general evolution.

The premise (based on science) leads to


, which can be identified in science fiction.

For example, the so-called

"grandfather paradox".

Marty McFly about to disappear, after coming between his mother and father, jeopardizing his own birth in the original Back to the Future movie.

For science, a paradox.

"What if I travel to a time before my grandfather conceived my father and kill him? My father would not be born, and therefore neither would I. This is an inconsistency. I cannot kill my grandfather because, in order for me to get on the time machine, it is necessary that he had not done it", argues Romero.


he unravels the knot of the first installment of the saga

, when Marty puts his own birth at risk.

Science, non-fiction: back to the future?

Behind doctor Romero there is a window that overlooks the property.

The bright sun illuminates the grass and a giant antenna that he works with daily.

His office has a blackboard with formulas, books, pens, a computer.

He never tires of talking about art, but his field is

pure and hard science.

Doctor Romero shows his blackboard, full of formulas and equations.

Photo: Constanza Niscovolos (Clarin).

With a didactic tone, he clarifies that

it is experimentally verified that one can travel in time

... at least

towards the future


"We can verify it, in principle, thanks to the particles with which we work in the laboratories."

This is due to a phenomenon called

"simultaneity of relativity"

, contemplated by the Special Theory of Relativity, which indicates that time passes at a different rate for a moving system compared to a system that is at rest.

"For example, if a particle that has a half-life of a millionth of a second is

moving at a considerable speed

, for us it can live for minutes."

Translation: regarding a particle similar to it, which remains in the laboratory, that particle is traveling into the future, because it gets to know instants of time that the one that remained at rest will never be able to see.

"It's as if there were two


and one of them was moving at great speed. That twin could get to know what happens in the year 2100, for example," Romero clarifies.

Even an astronaut who goes to the

International Space Station

, when he comes back, is a little bit younger than someone who stayed on Earth.

That experiment has also been done with atomic clocks and airplanes.

Another way to travel to the future is using


, adds the professor.

This is the case of

black holes

, objects with a very strong gravitational field, which bend space-time a lot.

Matt Damon in Interstellar.

Behind the plot was one of the best minds of this generation: the Nobel Prize in Physics, Kip Thorne.

"If one could go around their orbits a few times and return, they will notice that much more time has passed than for someone who continued on Earth. So, in some way, there was a trip to the future," says Romero.

This is exactly what happens in


, Christopher Nolan's film

advised by Kip Thorne.

The director of the Argentine Institute of Radio Astronomy knows that what attracts the most attention is the possibility of traveling to the past.

Before delving into the subject, he points out that the theory to study space-time is constantly evolving.

Long before Kip Thorne opened the door to wormholes

, the first person to seriously consider time travel was Kurt Gödel.

Mathematician, friend of Einstein and probably one of the most important logical philosophers since Aristotle.

Einstein's theory of general relativity: the scientific revolution that opened the game to physically thinking about time travel.

Romero seems like a book of stories, accounts and anecdotes.

"When Einstein turned 70, a book was published about him. As a contribution, Gödel gave him a new solution to his equations. These contained what we would call today 'closed time curves', which admitted the possibility of traveling to the past. When Einstein he saw it, he got worried. He ended up rejecting Gödel's proposal, not because it was incorrect (today we know he was right), but because it didn't apply to the real world," he recalls.

Gödel described a rotating universe.

Under these conditions, processes could be generated that would allow, through a journey towards one's local future, to reach a point in the global past.

"The question is whether something like this can be replicated without the need to manipulate the entire universe

," Romero hints.

For a long time it was believed not.

At least until the seventies, when the American physicist Frank Tipler recovered old writings by Willem Jacob van Stockum.

The latter had reached a conclusion similar to Gödel's, but in an environment of massive cylinders that rotated very quickly.

Now, the dilemma remained and continues: making a gigantic cylinder rotate, of apparently infinite length, is inapplicable in the real world.

Part of

an idealized, artificial situation.

Where does physics go when it dreams?

PhD in theoretical physics, astronomical researcher and writer Alan Lightman

he fantasized

what would go through Einstein's head

a few hours before he mailed the theory of time that would revolutionize science.

The man, slumped in his chair, dozes on papers riddled with formulas.

For months now, practical ideas have left him every time he closes his eyes:

he doesn't know if his research has taken over his dreams

of him, or if his dreams have taken over his research.

Throughout thirty short stories, this fabled Einstein puts together different configurations.

For example, that of a coexistence between a bodily time and a mechanical one;

another, where the end of the world exists and everyone knows when it will come;

and one where time is a circle that folds in on itself.

An image from the Webb telescope.

The light in this image is 4.6 billion years old.

Credit: NASA, ESA, CSA, and Space Telescope Science Institute

None of these ideas escaped the minds of scientists, who devoted articles and experiments to them.

Einstein himself showed his

poetic side

when, after the death of his friend Michele Besso, he wrote to the family: "He has now gone a little ahead of me in saying goodbye to this strange world. This means nothing. We, Physical devotees, we know that the distinction between past, present and future is nothing more than an illusion. Albeit a tenacious one."

Philosophy and hard sciences.

The man and his environment.

The finitude of the individual and the infinity of galaxies.

Fiction and reality(s).

After all, both humans and the universe are made up of

dreams, unknowns and stardust.

Source: clarin

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