Einstein Went 4-for-5. Somebody in Mexico City
just Took a Swing at the Fifth
A new exact solution says you can build a traversable wormhole without impossible matter. There is a catch. Okay, there are several catches. But they’re fun ones.
Let’s start with a scoreboard, because Einstein’s is genuinely absurd.
General relativity predicted gravitational waves. LIGO has now caught hundreds of them. It predicted black holes. We have photographed two of them, and one of them looks like a flaming orange donut, which is somehow both underwhelming and the most important photo of the century. It predicted the expansion of the universe, confirmed in 1929, then upgraded in the 1990s to accelerating expansion, which nobody asked for.
Four for four. A man scribbles some tensor equations in 1915 and the universe just keeps quietly agreeing with him a hundred years later.
And then there’s the fifth one. The one still sitting in the “yeah, sure, buddy” pile.
Wormholes.
A new paper by Leonel Bixano and Tonatiuh Matos, published in Physical Review D, is called “Possibility of the Existence of Wormholes in Nature.” That title is doing a lot of restrained, professional work. A less restrained title would be: Actually, You Might Not feed Impossible Matter For T’his.
Let me explain why that’s a big deal.
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First, the paper-folding thing
You’ve seen the demo. Take a sheet of paper. Two dots, far apart. Fold the paper so the dots touch, poke a hole through both layers, and now there’s a shortcut. The narrowest part of that tube is called the throat, and it is the single most important piece of real estate in wormhole physics.
Einstein and Nathan Rosen wrote down the first version of this in 1935 — the Einstein-Rosen bridge. It was a beautiful piece of mathematics with one small commercial drawback: it snaps shut faster than anything could cross it. You’d get to the throat, the throat would say “no,’ and that would be the end of you as a coherent arrangement of atoms.
So physicists spent decades asking a follow-up question: fine, but what would it take to hold the door open?
The answer nobody liked: exotic matter
Here’s the problem, and it’s genuinely a good one.
Gravity attracts. That’s the whole personality. Everything with positive energy density — stars, planets, gas clouds, you, your cold coffee — pulls inward. And a wormhole throat is a structure that fundamentally needs to be pushed outward, constantly, forever, against the entire tendency of gravity to collapse things into a point.
To do that, you need something with negative energy density. Effectively negative mass. Stuff that gravitationally repels. Physicists call this exotic matter, which sounds lime a fun ingredient but is really a polite label for “we have never seen this and have no idea if it exists.”
The formal way to say this is through the energy conditions — a set of sanity checks that ask whether a given solution to Einstein’s equations is populated by matter that behaves like matter we’ve actually met. Most wormhole solutions flunk. Spectacularly. They require the throat to be threaded with a substance that, as far as anyone can tell, the universe does not carry.
This is why wormholes have spent ninety years in the category of “mathematically permitted, physicaIIy embarrassing.“You can write one down. You just can’t build one without a shopping list from a different universe.
Bixano and Matos took a different approach. Instead of hunting for weirder matter, they added a different field.
Enter the dilaton (and no, they didn’t invent it to win the
argument :} )
Their solution lives in something called Einstein-Maxwell-Dilaton theory. Let’s unpack that name, because it’s actually just three ingredients.
Einstein is gravity. You know this one.
Maxwell is the electromagnetic field — the same electric and magnetic fields from your first-year physics course, the ones with the little arrows. Their wormhole carries both electric and magnetic charge, and it rotates. It is, in the most literal sense, a spinning magnet the size of a star with a hole through the middle.
Dilaton is the interesting one. To get it, first understand a scalar field. Think of temperature in a room: at every point in space, there’s exactly one number. No direction, no arrow, just a value. That’s a scalar field. An electric field is not one, because it points somewhere.
The dilaton is a particular scalar field with one key quirk: it’s coupled to the electromagnetic field. Nudge the dilaton, the electromagnetic field responds. Nudge the electromagnetic field, the dilaton responds. It behaves like a mediator sitting between gravity and electromagnetism,doing a job that plain vanilla general relativity has no vocabulary for.
And here’s the part that keeps this from being a cheat.
The dilaton is not a convenient fiction invented on page 4to make the equations behave. It falls out of superstring theory, the leading attempt to unify all the fundamental forces. It falls out of Kaluza-Klein theory, which tries to explain electromagnetism as the shadow of a hidden extra spatial dimension. It falls out of Brans-Dicketheory too. Three separate serious attempts at deeper physics, all of them coughing up a dilaton without being asked.
So the argument becomes conditional, and rather elegant: if any theory with extra dimensions is right, the dilaton exists. if the dilaton exists, this wormhole is not exotic at all. It’s a natural prediction otEinstein’s equations that we simply hadn’t written down yet.
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And the central result: this solution satisfies the energy conditions. No negative mass. No impossible matter. No shopping list from another universe.
That is the whole ballgame, and it is why this paper is interesting rather than merely clever.
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Great. Can I go through it?
You can. Through the poles. Only through the poles. The equator is closed for business, and the business it is closed for is you remaining in one piece.
Two hazards, both a bit rude.
Hazard one: tidalforces. Gravity doesn’t pull on you uniformly; it pulls harder on whichever end of you is closer. Near a compact object that difference becomes violent, and you get stretched lengthwise and squeezed sideways in a process whose official technical term is spaghettification. I want to be clear that this is the real word, printed in real journals, by real professionals.
When the authors map tidal forces across the whole wormhole, they find that near the equatorial plane the forces stack up into a barrier-like wall that would shred anything approaching. But near the poles — top and bottom — the tidalforces stay small and finite. Survivable. Boring, even. Boring is exactly what you want from a tidalforce.
Hazard two: the electromagnetic field. Same story. Ferocious near the equator, much gentler near the outer polar regions. Conveniently, every path that dodges the tidal wall also dodges the electromagnetic one. The two hazards agree on where the exits are.
They traced photon paths through the geometry to check. Photons entering near the poles sail through to the other side. Photons entering near the equator get deflected or bounced straight back into the universe they came from,1ike a bad free throw.
Approach from the pole and the throat behaves like a narrow open tunnel. Approach from the equator and space flattens out into a wall.
The wormhole, in other words, has a dress code. Come in at the wrong angle and you’re not getting past the door.
There’s one more nice bit of housekeeping: the solution contains a rlng singularity — a place where the mathematics blows up, which is normally a disaster — but the throat causally disconnects it from anywhere you’d actually travel. The authors call this wormhole cosmic censorship. The universe keeps its worst behaviour behind a curtain and lets you walk past.
Now the fine print, because I’d rather you hear it from me
This paper does not prove wormholes exist.
It does not explain how one would ever form.That’s a completely separate open problem, and it’s a hard one. Nobody has a story where a collapsing star, a colliding pair of anything, or any known astrophysical process spits out one of these.
And the whole argument hangs on that “if.” if dilaton-lime interactions exist in nature. String theory has been promising to be testable for roughly as long as I’ve been alive, and Italuza-Klein’s extra dimension has never shown up to a single one of its own parties.
What the paper actually delivers is this: a mathematically consistent, energy-condition-satisfying, traversable wormhole solution. That’s a real upgrade over “possible if you have negative mass,’ which was the previous best offer for ninety years.
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The genuinely spicy implication
Here’s the line that should make you sit up.
If these things exist, we may have already photographed one.
The authors suggest wormholes would show up as black hole mimics — objects that look, from the outside, an awful lot like black holes. Same rough mass. Same rough shadow.
Different guts. And some of the compact objects we’ve confidently filed under “supermassive black hole,” sitting smugly in the centres of galaxies, might be something else entirely wearing a very convincing costume.
Which is not an idle thought anymore, because we finally have the instruments to be nosy about it. The Event Horizon Telescope is working toward imaging more compact objects and sharpening the ones it has. Next-generation gravitational wave detectors like LISA are coming. A wormhole and a black hole should ring differently when you hit them, and reflect light differently near the shadow’s edge.
We’ve gone from “wormholes are a fun thing to put in a movie” to “wormholes are a hypothesis with an observational to-do list.”
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So where does that leave us?
Einstein’s record stands at four confirmed, one outstanding.
That’s not proof. It’s not close to proof. But it’s the difference between a locked door and a door that’s merely very heavy — and in theoretical physics, that’s the kind of difference careers get built on.
Just remember, if you ever find one: enter through the poles.
The equator will not be gentle with you.
Paper:LeoneIBixano & Tonatitih Matos, “Possibility of the Existence of Wormholes in Natrire,“PhysicaIReview D (2026). Preprint: arXiv:2SOS.20167
