A team in Vienna just put a solid speck of metal as massive as a small virus in 2 places at the same time, the largest object ever shown to obey quantum law.
Roughly 7,000 atoms of sodium, fixed by laser and split into a superposition, came back with the striped interference fingerprint that proves it never took one path.
Schrödinger's cat stopped being a metaphor in 2026.
What you'll learn:
✅ Why there's still no proven size limit on quantum mechanics
✅ What decoherence really explains about your solid, certain world
✅ Where the data ends and the meaning begins honestly
The wall between the quantum world and ours may have never really been there.
Schrödinger's Cat
A famous thought experiment in physics, devised by Erwin Schrödinger in 1935 to illustrate the perceived absurdity of quantum mechanics when applied to macroscopic objects (see below - Object Size).
He proposed this scenario in a letter to Albert Einstein to highlight the difficulties in interpreting quantum theory, specifically the Copenhagen interpretation.
The experiment involves a hypothetical cat placed in a sealed steel box with a "diabolical device."
This device consists of a radioactive atom, a Geiger counter, and a vial of poison gas.
If the radioactive atom decays, it triggers the Geiger counter, which in turn smashes the vial, releasing the poison and killing the cat.
If the atom does not decay, the cat lives.
The core of the thought experiment lies in the quantum superposition principle, which suggests that a subatomic particle can exist in multiple states simultaneously until observed.
Since the cat's fate is linked to the atom's state, the thought experiment posits that until the box is opened and the system is observed, the cat is paradoxically both alive and dead at the same time.
Schrödinger's intention with this thought experiment was not to propose that a cat could actually be both alive and dead, but rather to critique the implications of quantum mechanics and its interpretations.
He used the example to demonstrate the "weirdness" of the theory and to argue that it was incomplete or lacked sensible definitions, particularly concerning how quantum states translate to observable reality.
Schrödinger himself did not believe the cat was truly in a superposition of being alive and dead.
The experiment highlights the philosophical question of when exactly quantum superposition ends and reality resolves into a definite state, and how large a system needs to be to count as an "observation."
Recent experiments have pushed the boundaries of observing quantum phenomena in more massive systems, such as nanoparticles, which are described as being in a Schrödinger cat state, extending matter-wave interference to larger scales.
Quantum Mechanics and Object Size
Quantum mechanics describes the behavior of objects at very small scales, such as atoms, subatomic particles, and molecules, where particles can exist in multiple states simultaneously and communicate instantly across distances.
At this tiny scale, particles do not behave classically; instead, they can be in a superposition, where they are "smeared" across a range of possibilities, and they can be entangled, meaning multiple atoms can behave in lockstep.
The physics governing these small objects, known as quantum mechanics, allows for precise tuning of their behavior through seemingly minor alterations, such as adding or removing atoms or twisting material.
While quantum mechanics is most powerful when dealing with small objects, many physicists believe it applies to objects of all sizes, including macroscopic ones.
However, quantum effects become much harder to detect and measure as objects get larger, due to factors like heat, friction, and environmental interactions.
Although applying quantum mechanics to large objects would be computationally complex, it would often yield results similar to those predicted by classical mechanics.
Experiments have explored quantum interference with objects of increasing mass and complexity, including sodium nanoparticles containing over 7,000 atoms.
Despite these advancements, quantum effects have not been observed in laboratory settings for objects more massive than approximately 10^-20 grams, or a quintillionth of a gram (0.0000000000000000001)
The act of measurement itself is a key factor, as it can disturb an object's quantum nature and requires significant energy, further complicating observations at larger scales.
Perspectives
Quantum mechanics applies universally to all objects regardless of size.
Quantum mechanics can be used to describe the behavior of objects of all sizes, but its application to larger objects becomes extremely complex and often yields results similar to classical physics.
There is no known fundamental size cutoff for quantum mechanics, and in theory, it should apply to all objects.
Experiments have demonstrated quantum mechanical effects, such as flux quantization, in superconducting rings several centimeters in diameter and entanglement between light beams separated by kilometers.
Quantum mechanics is primarily effective for small objects, with its applicability to large objects being a complex and debated area.
Quantum mechanics is most powerful when dealing with small things like atoms, subatomic particles, and molecules, and as systems get bigger, quantum effects become harder to detect.
The transition from quantum to classical mechanics is not based on a sharp mass cutoff, and some scientists previously thought that quantum mechanics might not apply to sufficiently large systems.
Challenges in observing quantum phenomena in larger objects are often attributed to factors such as heat, friction, and environmental interactions, which cause quantum states to decohere.
Quantum effects have not been observed in laboratory settings for objects more massive than approximately 10^-20 grams
