The universe is accelerating. Every galaxy beyond our local group is moving away from us, and the further away it is, the faster it recedes. This has been measured with extraordinary precision using supernovae, the cosmic microwave background, and galaxy surveys. It is one of the most firmly established facts in modern cosmology.
It is also deeply mysterious. According to Einstein’s general theory of relativity, a universe filled only with matter and radiation should be slowing down — gravity should be pulling everything back together. Instead, the universe is speeding up. Something is pushing space apart, and physicists do not know what it is.
The leading placeholder is called dark energy — a name that means, essentially, “we do not know.” Dark energy accounts for approximately 68% of the total energy content of the observable universe, yet it has never been directly detected. It leaves no trace in any laboratory experiment. We know it is there only because the universe behaves as though it is.
Now, a study published in the journal Physical Review D proposes a radical new candidate for dark energy: microscopic wormholes, ceaselessly born and destroyed in the quantum vacuum of space. If correct, this would be one of the most consequential ideas in the history of cosmology — connecting the largest structures in the universe to the smallest scales of quantum gravity.
What Is Dark Energy and Why Is It a Problem?
To appreciate why the wormhole proposal matters, it helps to understand just how severe the dark energy problem is.
When Einstein first formulated general relativity in 1915, he introduced a term called the cosmological constant — a kind of built-in repulsive energy of space itself — to produce a static universe, because the idea of an expanding or contracting universe seemed physically implausible to him. When Edwin Hubble observed in 1929 that galaxies were receding from us in every direction, Einstein abandoned the cosmological constant, calling it his “greatest blunder.”
In 1998, two independent teams studying distant Type Ia supernovae — which function as “standard candles” for measuring cosmic distances — discovered that the expansion of the universe is not just continuing but accelerating. The cosmological constant was brought back from the dead. Renamed dark energy, it was reinstated as the most economical explanation for what the observations required.
The problem is that when physicists try to calculate the value of the cosmological constant from first principles using quantum field theory, they get an answer that is roughly 10 to the power of 120 times larger than what is actually observed — the largest discrepancy between theory and observation in the history of science. This is sometimes called the cosmological constant problem, and it is one of the most serious unsolved problems in theoretical physics.
Various alternatives to the cosmological constant have been proposed over the years. Quintessence — a dynamic field that changes over time — is one. Modified gravity theories are another. The wormhole proposal is among the most recent and most intriguing.
What Is a Wormhole?
A wormhole — formally called an Einstein-Rosen bridge — is a hypothetical structure in spacetime that connects two separate regions of space, or even two different points in time, through a shortcut that bypasses the ordinary geometry of the universe.
Wormholes emerge naturally from the mathematics of general relativity. Einstein and Nathan Rosen first described them in 1935 as a consequence of the field equations, though they noted that such structures would be inherently unstable and would collapse before anything could pass through them. The traversable wormholes of science fiction — stable tunnels that a spaceship could use to travel between stars — require exotic matter with negative energy density to hold them open, and no such material has ever been observed.
But the wormholes in the new proposal are not the large, traversable structures of science fiction. They are subatomic — vanishingly small fluctuations at the Planck scale, the smallest meaningful length in physics (approximately 10 to the power of −35 metres). At this scale, spacetime itself is thought to be subject to quantum fluctuations, foaming and bubbling with transient geometric structures that appear and disappear too rapidly to be directly observed.
These quantum wormholes are not exotic speculations. They have been discussed in theoretical physics since John Wheeler proposed the concept of “quantum foam” in the 1950s. What the new research adds is a precise calculation of how often they are created and destroyed — and a proposal that this process contributes measurably to the energy density of the vacuum.
The New Research: Wormholes as Dark Energy
The study, published in Physical Review D, uses an approach called Euclidean quantum gravity to calculate the rate at which microscopic wormholes are spontaneously created from the quantum vacuum of space.
In ordinary quantum field theory, virtual particles — temporary fluctuations of energy that borrow existence from Heisenberg’s uncertainty principle — constantly appear and disappear throughout the vacuum. The energy associated with these fluctuations contributes to the vacuum energy of space. The wormhole proposal extends this framework to include fluctuations not just in particle fields but in spacetime geometry itself — quantum gravitational effects that produce transient wormhole structures.
The researchers found that the continuous creation and annihilation of these microscopic wormholes produces an effective energy contribution to the vacuum — one that behaves, in its large-scale effects, like dark energy. Crucially, this dark energy is not constant. It evolves over time as the wormhole creation rate changes with the expansion of the universe, producing a dynamic dark energy rather than the fixed cosmological constant of the standard model.
This is significant because recent astronomical observations — particularly from the Dark Energy Spectroscopic Instrument (DESI) survey, which mapped the positions of tens of millions of galaxies — have suggested that the rate of cosmic expansion may have changed over the history of the universe in ways inconsistent with a perfectly constant dark energy. A dynamic dark energy, one that evolves over time, fits these observations better. The wormhole model naturally produces exactly this kind of dynamic behaviour.
Why This Is Different From Other Quantum Effects
The researchers are careful to distinguish their proposal from other quantum vacuum phenomena that might seem superficially similar.
Hawking radiation — the slow evaporation of black holes through quantum effects at their event horizons — is a well-established theoretical prediction involving quantum fields in curved spacetime. The Schwinger effect — the spontaneous creation of particle-antiparticle pairs in an intense electric field — is another. Both of these involve quantum fields operating on a fixed spacetime background.
The wormhole mechanism is different in a fundamental way: it requires quantum effects in gravity itself — the geometry of spacetime must be treated quantum mechanically, not merely as a fixed arena in which quantum fields operate. This places the proposal firmly in the domain of quantum gravity, the not-yet-completed theory that would unify general relativity with quantum mechanics.
The authors derived their result using Euclidean quantum gravity — a mathematical technique in which time is treated as an imaginary number, converting the problem into one involving Euclidean rather than Lorentzian geometry. This approach has been used productively in quantum gravity since the 1970s, most famously by Stephen Hawking and James Hartle in their no-boundary proposal for the origin of the universe. While not universally accepted as a complete theory, it is a well-established and mathematically rigorous framework within which to perform the calculation.
How Well Does the Model Fit the Observations?
The team compared their wormhole-based dark energy model against the current observational data and found that it fits better than the standard cosmological model — the Lambda-CDM model — which treats dark energy as a fixed cosmological constant.
The key advantage is the dynamic nature of the model’s dark energy. Recent data from DESI, combined with measurements of the cosmic microwave background and Type Ia supernovae, has created mild but persistent tension within the standard model. These datasets collectively suggest that the universe’s expansion history is not perfectly described by a constant dark energy. The wormhole model’s time-varying dark energy alleviates this tension in a physically motivated way.
This does not mean the model is confirmed. Fitting existing data better than a competitor is necessary but not sufficient for a theory to be accepted. What is required is a distinctive prediction — something the wormhole model predicts that other models do not — that can be tested by future observations.
The Challenge: Can It Be Tested?
This is where the proposal faces its most serious current limitation. For now, the theory remains untestable with existing instruments. The microscopic wormholes are far too small to be observed directly, and their collective effect on dark energy is currently indistinguishable from other dynamic dark energy models through existing surveys alone.
The researchers acknowledge this limitation directly and frame it as a target for future research. The next generation of cosmological surveys — including the European Space Agency’s Euclid mission, currently operational, and the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST), which began operations in 2025 — will map the large-scale structure of the universe with unprecedented precision. These surveys should be able to measure the evolution of dark energy over cosmic time with enough accuracy to distinguish between competing models.
If the wormhole model’s specific predictions for how dark energy evolves — derived from the Euclidean quantum gravity calculation — match what Euclid and Rubin observe, it would be a powerful indication that microscopic wormholes are real and that quantum gravity leaves a measurable imprint on the largest scales of the cosmos.
The Deeper Significance: Connecting the Very Small to the Very Large
Beyond its practical implications for cosmology, the wormhole proposal carries a deeper theoretical significance. It represents one of the few concrete proposals for how quantum gravitational effects — which operate at scales roughly 20 orders of magnitude smaller than an atomic nucleus — might leave observable traces at cosmological scales.
This connection between the very small and the very large is one of the central goals of theoretical physics. The two pillars of modern physics — general relativity, which describes gravity and the large-scale structure of spacetime, and quantum mechanics, which describes the behaviour of particles and fields at microscopic scales — are incompatible with each other in their current forms. Combining them into a single consistent theory of quantum gravity is the deepest unsolved problem in physics.
The wormhole dark energy proposal suggests that the cosmological constant problem — why the vacuum energy calculated from quantum field theory is so different from what is observed — might find its resolution in quantum gravitational effects that have simply been left out of the standard calculation. If wormholes contribute to vacuum energy in the way the authors propose, they could help explain why the observed dark energy is so much smaller than naive quantum field theory predicts.
Understanding quantum entanglement — the deep non-local connections between particles first explored in the context of quantum mechanics — may also be connected to wormhole physics. The ER=EPR conjecture, proposed by Juan Maldacena and Leonard Susskind in 2013, suggests that entangled particles are connected by microscopic wormholes. If correct, this would mean that entanglement and spacetime geometry are two aspects of the same underlying phenomenon. For a full introduction to entanglement and its implications, see our article on quantum entanglement: the mystery at the heart of quantum mechanics.
The physicist Richard Feynman — who pioneered quantum electrodynamics and spent his career pushing at the boundaries of what quantum mechanics could explain — famously said that anyone who claims to understand quantum mechanics does not understand quantum mechanics. The wormhole proposal reminds us that the deepest mysteries of the quantum world are not confined to the laboratory. They may be written across the sky. For more on Feynman’s life and legacy, see our article on Richard Feynman: the Nobel Prize physicist who called curiosity his greatest scientific instrument.
What Comes Next
The wormhole dark energy proposal is a young idea in a fast-moving field. Its authors have made a clear, mathematically rigorous prediction: dark energy evolves over time in a specific way, determined by the wormhole creation rate derived from Euclidean quantum gravity. That prediction is now in the queue to be tested.
The Euclid mission is already returning data. The Rubin Observatory began its decade-long survey of the southern sky in 2025. The Nancy Grace Roman Space Telescope, due to launch in the late 2020s, will add further precision. Together, these instruments will give cosmologists the most detailed picture ever assembled of how the universe’s expansion has evolved — and whether dark energy is constant or changing.
If the data matches the wormhole model’s predictions, it will open a new chapter in physics: one in which quantum gravity is no longer only a theoretical aspiration but an observationally confirmed contributor to cosmic evolution. If it does not match, the proposal will join the long list of elegant ideas that nature declined to adopt — and physicists will continue searching for the true identity of dark energy, one of the universe’s most stubborn secrets.
For related reading on the physics of time and why the universe evolves in one direction, see our article on the arrow of time: why physics says time only moves forward.
Frequently Asked Questions
What is a wormhole?
A wormhole, formally called an Einstein-Rosen bridge, is a hypothetical structure in spacetime that connects two separate regions of space — or time — through a shortcut bypassing ordinary geometry. Wormholes emerge from the mathematics of Einstein’s general relativity. Large traversable wormholes of science fiction would require exotic matter to remain stable, but microscopic quantum wormholes are a separate theoretical concept operating at the Planck scale.
What is dark energy?
Dark energy is the name given to whatever is causing the accelerated expansion of the universe. It accounts for approximately 68% of the total energy content of the observable universe. It has never been directly detected and interacts so weakly with matter and radiation that it leaves no trace in laboratory experiments. Its nature is one of the deepest unsolved problems in physics.
How could wormholes cause the universe to expand faster?
According to the new research, microscopic wormholes are constantly being created and destroyed in the quantum vacuum of space. This process contributes energy to the vacuum — energy that behaves like dark energy on cosmological scales, producing an effective repulsive pressure that drives the accelerated expansion of the universe.
What is Euclidean quantum gravity?
Euclidean quantum gravity is a mathematical technique in which time is treated as an imaginary number, converting the equations of quantum gravity into a mathematically more tractable form involving Euclidean geometry. It has been used in theoretical physics since the 1970s, most famously by Hawking and Hartle. It is not a complete theory of quantum gravity but is a productive framework for performing specific calculations.
Has this theory been confirmed by observations?
Not yet. The model fits existing observational data better than the standard cosmological model, but it has not yet produced a distinctive prediction that has been tested. Future surveys including the Euclid mission and the Rubin Observatory’s LSST should provide data precise enough to test whether dark energy evolves over time in the way the wormhole model predicts.
What is the connection between wormholes and quantum entanglement?
The ER=EPR conjecture, proposed by Maldacena and Susskind in 2013, suggests that entangled particles are connected by microscopic wormholes — that quantum entanglement and Einstein-Rosen bridges are two descriptions of the same underlying phenomenon. This remains a theoretical conjecture but has generated significant research activity and may be relevant to the wormhole dark energy proposal.
Further Reading
- Physical Review D — Journal of Particles, Fields, Gravitation and Cosmology
- ESA — Euclid Mission Overview
- Vera C. Rubin Observatory — LSST
- Wikipedia — The Cosmological Constant Problem
- The Biggest Ideas in the Universe by Sean Carroll — an accessible guide to spacetime, quantum mechanics, and cosmology
Sources
- Physical Review D — Original Research Journal
- Wikipedia — Wormhole
- Wikipedia — Dark Energy
- Wikipedia — Cosmological Constant
- Wikipedia — Euclidean Quantum Gravity
- Dark Energy Spectroscopic Instrument (DESI)
- ESA Euclid Mission
- Web News For Us — Quantum Entanglement Explained
- Web News For Us — The Arrow of Time
- Web News For Us — Richard Feynman
About the Author
Baryon is the writer and editor behind Web News For Us. Fascinated by the big unanswered questions in physics and cosmology — from the arrow of time to the nature of consciousness and the possibility of parallel universes — he also deeply explores the lives, wisdom, and timeless teachings of legendary thinkers, mystics, and spirit
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