Scientists confirm zero-point energy persists in molecules at near absolute zero

The energy you cannot remove

Scientists at the European X-Ray Free-Electron Laser Facility confirmed in 2025 that molecules never stop moving. Even when researchers cool matter to temperatures approaching absolute zero, an internal residue of motion remains. This phenomenon, known as zero-point energy, represents the lowest possible energy state a quantum system can occupy. The research team focused on iodopyridine, an organic molecule composed of 11 atoms. They chilled the molecule to its ground state and then used a high-intensity laser pulse to break its atomic bonds. By measuring the trajectories of the freed atoms, the team observed correlated motions that proved the molecule was vibrating before the laser hit it. Experimental physicist Rebecca Boll noted that the discovery was an accidental byproduct of their primary research. The data showed that even in a state of supposed rest, the atoms maintained a baseline level of activity. This "jiggling" is not a result of heat, but a fundamental requirement of quantum mechanics.

Why particles must keep jiggling

The existence of zero-point energy stems directly from the Heisenberg uncertainty principle. This rule states that you cannot simultaneously know the exact position and the exact momentum of a particle. If a particle were to stop moving entirely at a specific location, both values would be fixed, which the laws of physics forbid. To visualize this, physicists often use the analogy of a ball at the bottom of a valley. In classical physics, a ball at the lowest point of a curve has zero kinetic energy and minimum potential energy. In the quantum version, the ball must fluctuate slightly around that bottom point to maintain uncertainty. This mandatory motion applies to two distinct categories of physical reality:

• Discrete objects: Individual atoms and molecules held in place by chemical bonds or electrical fields.
• Quantum fields: The underlying fabrics of the universe, such as the electromagnetic field, which permeate all of space.

Because these fields and particles are always slightly "confined" by their environment or their own nature, they can never reach a state of true zero energy. You can dampen the vibrations of a field, but you cannot eliminate the field itself.

Measuring the force of nothing

The most famous evidence for zero-point energy is the Casimir effect, first predicted by Hendrick Casimir in 1948. Casimir proposed that two uncharged metallic plates placed extremely close together in a vacuum would experience a physical force pushing them toward each other. This force arises because the plates restrict the types of energy waves that can exist between them. The plates act as a mathematical "guillotine" for the electromagnetic field. They block long-wavelength oscillations from forming in the narrow gap, while the full spectrum of wavelengths continues to exist outside the plates. This creates an energy imbalance where the pressure from the outside is higher than the pressure from the inside. Physicists struggled to prove this theory for decades due to the extreme precision required.

• 1958: Researchers saw the first hints of the effect but lacked definitive proof.
• 1997: Scientists finally achieved a precise measurement that matched Casimir’s mathematical predictions.
• 2025: Modern experiments continue to use the effect to study the limits of the quantum vacuum.

This force demonstrates that the vacuum is not empty. It is a medium with physical properties that can exert measurable pressure on solid objects.

The universe should have exploded

While zero-point energy is a proven fact in small-scale experiments, it creates a massive contradiction in cosmology. Quantum field theorists view every field as a collection of infinite oscillators, each contributing its own zero-point energy. When you add up these infinite contributions, the total energy density of the vacuum becomes mathematically infinite. Physicists usually solve this by "subtracting" the infinities to find the difference between energy states. In most branches of physics, only the change in energy matters, not the absolute total. However, gravity does not allow for this mathematical shortcut because gravity reacts to the absolute amount of energy present. In 1946, Wolfgang Pauli calculated that the zero-point energy of the vacuum should be so high that its gravitational pull would cause the universe to curl up or explode. Sean Carroll, a physicist at Johns Hopkins University, explains that because all forms of energy gravitate, the vacuum energy should be a dominant force in the evolution of the cosmos. The fact that the universe still exists suggests that our understanding of vacuum energy or gravity is incomplete. This discrepancy is often called the cosmological constant problem, and it remains one of the largest gaps in modern scientific knowledge.

A vacuum filled with potential

The modern understanding of the vacuum has shifted from "nothingness" to a state of "potential." Peter Milonni of the University of Rochester describes the vacuum as a place where every possible particle is represented by its underlying field. Even in a volume of space with no actual electrons, the vacuum contains "electronness"—the field that allows electrons to exist. Zero-point energy is the cumulative effect of every form of matter and every force in the universe, including those that have not yet been discovered. It serves as the baseline for the following:

• Stability of matter: It prevents atoms from collapsing in on themselves.
• Phase changes: It explains why liquid helium does not freeze at standard pressure, even at temperatures near absolute zero.
• Particle creation: It provides the energy fluctuations that allow virtual particles to pop in and out of existence.

Because this energy is tied to the structure of space itself, it is impossible to extract or use as a power source. It is the floor of the universe, a level of activity that cannot be lowered. Every attempt to "empty" a box will eventually hit this wall of quantum noise, proving that a true void cannot exist in our physical reality.