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An illustration of matter pouring into a black hole, crossing the Einstein-Rosen Bridge and emerging into another region of the universe. | Credit: Robert Lee (created with Canva)
This article was originally published on conversation The publication contributed the article to Space.com Expert Voices: Op-Ed and Insights.
Wormholes Often imagined as tunnels through space or time—shortcuts to the universe. But this image is based on a misunderstanding of the work of physicists Albert Einstein and Nathan Rosen.
In 1935, while studying the behavior of particles in extreme gravitational fields, Einstein and Rosen introduced what they called “the bridge”.: A mathematical link between two perfectly symmetrical copies space time. It was not meant as a path for travel, but as a path To maintain stability Between gravity and quantum physics. Only later did Einstein-Rosen bridges become associated with wormholes, albeit with little connection to the original idea.
but in New researchMy colleagues and I show that the original Einstein–Rosen bridge points to something much stranger — and much more fundamental — than a wormhole.
The puzzle that Einstein and Rosen addressed was never about space travel, but about how quantum fields behave in curved spacetime. Explained this way, the Einstein-Rosen Bridge acts as a mirror in spacetime: a connection between two microscopic arrows of time.
Quantum mechanics deals with nature at the smallest scales like particles, while Einstein’s The theory of general relativity Applies to gravity and spacetime. Reconciling the two is one of the most profound challenges in physics. And excitingly, our reinterpretation may offer a way to do this.
A Misunderstood Legacy
The “wormhole” explanation emerged decades after the work of Einstein and Rosen, when physicists hypothesized that space-time would cross from one end to the other. Most notably in research from the 1980s.
But those same analyzes also made clear how speculative the idea was: within general relativity, such travel is forbidden. This bridge closes faster than light can pass through, rendering it impassable. Einstein-Rosen bridges are therefore unstable and disordered — mathematical structures, not portals.
Nevertheless, the wormhole metaphor flourished in popular culture and speculative theoretical physics. The idea that Black holes Can connect — or even work — distant regions of the universe Time machines – Inspired countless papers, books and movies.
Yet there is no observational evidence for macroscopic wormholes, nor is there any compelling theoretical reason to expect them within Einstein’s theory. While the physical sciences instead of extension – eg Foreign forms of matter or A modification of general relativity – have been proposed to support such structures, they remain unknown and highly speculative.
An artist’s interpretation of using a wormhole to travel through space. | Credit: NASA
The two arrows of time
Our current work revisits the Einstein-Rosen bridge puzzle using a modern quantum interpretation of time, building on ideas developed by Shravan Kumar and Joao Marto.
Most of the time Basic laws of physics Don’t distinguish between past and future, or left and right. If time or space are reversed in their equations, the laws remain valid. Taking these symmetries seriously leads to a different interpretation of the Einstein-Rosen bridge.
Instead of tunneling through space, it can be understood as two complementary components of a quantum state. In one, time moves forward; In another, it flows backwards from its mirror-reflected position.
This symmetry is not a philosophical preference. Once infinities are excluded, quantum evolution should be complete and reversible at the microscopic level – even in the presence of gravity.
“Bridge” expresses the fact that both time components are needed to describe a complete physical system. Under normal circumstances, physicists ignore the time-reversal component by choosing a single arrow of time.
But near black holes, or in expanding and collapsing universes, both directions must be included for a coherent quantum description. Here the Einstein-Rosen bridges arise naturally.
Resolve information paradoxes
At the microscopic level, the bridge allows us to pass what appears as information event horizon – Point of no return. Information is not lost; It continues to develop, but with the opposite, mirror temporal direction.
This framework provides a natural resolution for the famous black hole information paradox. In 1974, Stephen Hawking showed That black holes radiate heat and can eventually evaporate, apparently erasing all information about what fell into them—contradicting the quantum theory that evolution should preserve information.
The paradox arises if we insist on describing horizons using a single, one-sided arrow of time extrapolated to infinity—an assumption not required by quantum mechanics itself.
If the full quantum description includes both time directions, nothing is lost. Information leaves our time direction and re-emerges simultaneously in reverse. Completeness and functionality are preserved, without invoking exotic new physics.
These ideas are difficult to understand because we are macroscopic beings who experience only one direction of time. On daily scales, disorder – or entropy – increases. A highly ordered state naturally evolves into a disordered state, never the other way around. This gives us the arrow of time.
But quantum mechanics allows for more subtle behavior. Interestingly, evidence of this hidden structure may already exist. The cosmic microwave background – the afterglow of Big Bang – Shows small but persistent asymmetry: A preference for a spatial orientation in its mirror image.
This anomaly has puzzled cosmologists for two decades. Standard models assign this to an extremely low probability – unless mirror quantum components are included.
An echo of an earlier universe?
This image is naturally associated with deeper possibilities. What we call the “Big Bang” may not have been an absolute beginning, but a leap—a quantum transition between two time-opposite stages of cosmic evolution.
In such a scenario, black holes can act as bridges not only between time directions but also between different cosmic epochs. Our universe A black hole may have an interior Another, formed in the parent universe. It may have formed as a closed region of spacetime collapsed, bounced back, and began to expand into the universe we observe today.
If this picture is correct, it also provides a way to judge observations. Remnants of the pre-bounce phase – such as small black holes – may survive the transition and reappear in our expanding universe. Some of the invisible objects we attribute to dark matter may, in fact, be composed of such remnants.
In this view, the Big Bang evolved from an earlier contraction state. Wormholes are not needed: the bridge is temporal, not spatial — and the Big Bang becomes an entrance, not a beginning.
This reinterpretation of the Einstein-Rosen Bridge offers no shortcuts to galaxies, no time travel and no science-fiction wormholes or Hyperspace. What it gives is very profound. This provides a coherent quantum picture of gravity in which spacetime embodies a balance between opposite directions of time – and where our universe may have had a history before the Big Bang.
It doesn’t overturn Einstein’s relativity or quantum physics – it complements them. The next revolution in physics may not hit us faster than light—but it may reveal that time, deep down in the microscopic world and in the bouncing universe, flows both ways.
