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Wormholes are a very common idea in science fiction. People often think of them as tunnels that let travelers jump instantly between faraway places in space and time. However, this popular picture is based on a misunderstanding of the real work done by Albert Einstein and Nathan Rosen. In 1935, these two scientists studied particles moving in areas with very strong gravity. They created a mathematical idea they called a "bridge." This bridge connected two identical copies of spacetime.
Their main goal was not to build a road for travel. Instead, they wanted to make sure the laws of gravity matched the new field of quantum physics. It was only many years later that people started calling these bridges "wormholes." This name does not fit the original work of the physicists very well. The idea that these structures are wormholes came to life long after Einstein and Rosen did their work. Scientists in the late 1980s began to guess if a person could cross from one side of the bridge to the other.
But their own research showed how unrealistic this idea really is. According to Einstein's own theory of general relativity, such a trip is physically impossible. The bridge would close up faster than light could travel through it. This makes the bridge impossible to cross. Therefore, Einstein-Rosen bridges are unstable and cannot be seen. They are math ideas, not physical doors that a human can walk through.
Despite this, the story of wormholes has become very popular. It is found in movies, books, and some scientific papers. The idea that black holes might connect different parts of the universe, or even act as time machines, has inspired many people. However, there is no proof that large wormholes exist in the real world. There is also no strong reason in Einstein's original theory to believe they are real.
Some new ideas in physics suggest they might exist, but these ideas have not been tested yet.
Our recent research looks at the Einstein-Rosen bridge puzzle using a modern view of time from quantum physics. This work builds on ideas from other scientists over the years. Most basic laws of physics do not tell the past from the future. If you reverse time in their equations, the laws still work perfectly. Taking this symmetry seriously leads to a very different way of understanding the bridge.
Instead of being a tunnel through space, the bridge can be seen as two parts of a single quantum state. In one part, time moves forward just as we experience it. In the other part, which is a mirror image, time moves backward. This symmetry is not just a choice of philosophy. At the smallest scale, quantum evolution must be complete and reversible, even when gravity is involved. The bridge shows that both parts of time are needed to describe a complete physical system.
In normal situations, scientists ignore the time-reversed part by choosing just one direction for time. But near black holes, or in universes that are growing or shrinking, both directions of time must be included for a clear description. It is in these extreme situations that Einstein-Rosen bridges appear naturally. They act as the necessary connectors for these systems with two time directions.
At the smallest level, this bridge allows information to cross what we call an event horizon. This is the point of no return around a black hole. Information does not disappear or get destroyed. It continues to change, but it does so along the opposite, mirrored direction of time. This idea offers a natural solution to the famous black hole information paradox. In 1974, Stephen Hawking showed that black holes emit heat and can eventually evaporate completely. This finding seemed to mean that all information about things that fell into the black hole would be erased.
This result contradicted a main rule of quantum mechanics. That rule says information must always be kept and never lost. The paradox only happens if we insist on describing black hole edges with only one direction of time. Quantum mechanics itself does not need this assumption. If the full description includes both directions of time, nothing is truly lost. Information simply leaves our forward time and comes back along the reversed time.
Completeness and cause-and-effect are kept without needing strange new physics. These ideas are hard to understand because we are big beings. We only feel one direction of time. On a daily scale, disorder, or entropy, always goes up. A very ordered state naturally becomes disordered, not the other way around. This gives us our strong feeling that time moves from the past to the future.
Quantum mechanics, however, allows for more subtle behavior at the smallest scales. Interestingly, there might already be proof of this hidden, two-sided structure. The cosmic microwave background is the faint afterglow of the Big Bang. It shows a small but lasting difference. It prefers one direction over its mirror image. This mystery has puzzled scientists for twenty years. Standard models say it is very unlikely to happen by chance, unless these mirrored quantum parts are included in the description of the early universe.
This picture connects to a deeper possibility. What we call the "Big Bang" might not have been an absolute start. It could have been a bounce, a quantum change between two time-reversed phases of cosmic growth. In this scenario, black holes could act as bridges not just between opposite time directions, but between different time periods in the universe. Our universe might be the inside of a black hole that formed in another, parent cosmos.
This parent cosmos could have formed when a closed area of spacetime collapsed, then bounced back and began expanding as the universe we see today. If this picture is correct, it also suggests a way for us to test it. Remnants from before the bounce, like smaller black holes, could survive the change and appear in our expanding universe. Some of the unseen matter we call dark matter could actually be made of these ancient leftovers.
From this view, the Big Bang grew from conditions in a previous shrinking. Wormholes are not needed for this model. The bridge is about time, not space. The Big Bang becomes a gateway, not a definite beginning. This new way of seeing Einstein-Rosen bridges offers no shortcuts across galaxies, no time travel machines, and no sci-fi wormholes. What it offers is much more profound. It provides a consistent quantum picture of gravity where spacetime shows a balance between opposite time directions.
It suggests our universe might have had a history before the Big Bang. It does not destroy Einstein's relativity or quantum physics. Instead, it tries to finish them. The next revolution in physics might not let us travel faster than light. But it could reveal that time, deep inside the microscopic world and in a bouncing universe, flows both ways. This creates a unified bridge between the past and the future.