{"id":303363,"date":"2025-07-30T07:45:12","date_gmt":"2025-07-30T07:45:12","guid":{"rendered":"https:\/\/www.europesays.com\/uk\/303363\/"},"modified":"2025-07-30T07:45:12","modified_gmt":"2025-07-30T07:45:12","slug":"einstein-was-wrong-idealized-double-slit-experiment-ends-nearly-100-year-old-debate","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/uk\/303363\/","title":{"rendered":"Einstein Was Wrong? \u2018Idealized\u2019 Double-Slit Experiment Ends Nearly 100-Year-Old Debate"},"content":{"rendered":"

Massachusetts Institute of Technology (MIT) scientists performing what they described as an \u201cidealized\u201d version of the infamous double-slit experiment<\/a>, showing light exists as both a particle and a wave<\/a>, a core component of quantum physics<\/a>, have confirmed the original test\u2019s results and proven that a related proposal about light\u2019s dual nature from famed scientist Albert Einstein<\/a> was wrong.<\/p>\n

The MIT team noted that the ability to utilize advanced 21st-century technology a century after the birth of quantum physics, resolving a disagreement between Einstein and physicist Niels Bohr that occurred only two years later, makes the discovery serendipitous and somewhat more satisfying.<\/p>\n

\u201cIt\u2019s a wonderful coincidence that we could help clarify this historic controversy in the same year we celebrate quantum physics,\u201d said study co-author Yoo Kyung Lee.<\/p>\n

As the name implies, the original double-slit experiment, first conceived in 1801 by British scholar Thomas Young to demonstrate light\u2019s wavelike nature, involved flashing a light through a pair of slits and observing the patterns they created on a screen on the other side. Although quantum physics would not be formally described for another 124 years, those early demonstrations proved one of its critical components: the dual nature of light<\/a>.<\/p>\n

Specifically, these experiments showed light existed as both a particle and a wave, since light passing through the dual slits appears as an alternating pattern of light and dark stripes called an interference pattern, indicating it is a wave. When one tries to determine which slit the light passed through, the interference pattern disappears, revealing light as a particle.<\/p>\n

The double-slit experiment also revealed another puzzling aspect of light\u2019s dual nature. Although light could exist as either a particle or a wave, one could not simultaneously observe it as both. According to a statement<\/a> announcing the new, idealized experiments, seeing light in its particle form instantly obscures its wavelike nature. Conversely, when light is observed as a wave, its particle nature is instantly obscured.<\/p>\n

\"EinsteinImage by WikiImages<\/a> from Pixabay<\/a><\/p>\n

Because many of the core concepts underlying quantum physics were untestable with the tools available to early 20th-century scientists, the immutability of light\u2019s dual nature was a point of contention. In 1927, Einstein proposed that a photon passing through a slit would impart a tiny momentum recoil to it\u2014akin to a bird ruffling leaves as it flies past. If such a recoil could be measured without destroying the interference pattern, it would suggest that light\u2019s wave and particle properties could be observed simultaneously.<\/p>\n

To demonstrate this, Einstein proposed a theoretical experiment in which the slits were supported by extremely sensitive springs. If his idea was correct, when a photon passed through a slit, the sensitive springs would detect the minuscule force acting on the slit due to the photon\u2019s passage, showing it was a particle. If the interference pattern indicating it was a wave was also observed, the dual nature of light would be revealed simultaneously.<\/p>\n

Bohr immediately disagreed with Einstein\u2019s proposal, based on the quantum physics concept known as the uncertainty principle. According to Bohr\u2019s interpretation, merely the act of detecting the particle\u2019s path with the springs would \u201cwash out\u201d the interference pattern and only reveal the light as a particle. Because the technology to test such a fine difference wasn\u2019t available at the time, the argument has gone unresolved for nearly 100 years.<\/p>\n

To create their idealized version of the double slit experiment capable of detecting Einstein\u2019s proposed particle force and light\u2019s wavelike nature simultaneously, Lee and colleagues utilized more than 10,000 atoms cooled to microkelvin temperatures. They then used a laser array to suspend the atoms in space and then configure them into an evenly spaced, crystal-like lattice configuration. The team stated that this architecture enabled\u00a0adjacent pairs of atoms to act as idealized slits, and using over 10,000 atoms significantly improved the signal-to-noise ratio compared to just a single atom or pair.<\/p>\n

\"double-slitSchematic of the MIT experiment: Two single atoms floating in a vacuum chamber are illuminated by a laser beam and act as the two slits. The interference of the scattered light is recorded using a highly sensitive camera, which is displayed on a screen. Incoherent light appears as background and implies that the photon has acted as a particle passing only through one slit (Image Credit: Courtesy of Wolfgang Ketterle, Vitaly Fedoseev, Hanzhen Lin, Yu-Kun Lu, Yoo Kyung Lee, and Jiahao Lyu).<\/p>\n

Based on previous unrelated experiments, the team suspected that if they shone a \u201cweak\u201d light through their suspended, 10,000-atom lattice, they could observe a single photon scatter off two adjacent atoms as either a particle or a wave. Wolfgang Ketterle, the John D. MacArthur Professor of Physics and leader of the MIT team, said this setup \u201ccan be regarded\u201d as an idealized variant of the traditional double-slit experiment that is so sensitive it operates at the quantum level.<\/p>\n

\u201cThese single atoms are like the smallest slits you could possibly build,\u201d Professor Ketterle explained.<\/p>\n

Before testing Einstein\u2019s idea, the team \u201ctuned\u201d the apparatus until half of the photons were observed as particles and half as waves. This team said this tuning method adjusted either the \u201cfuzziness\u201d of an individual atom or the certainty of its location. By tightening or loosening the hold of the laser light on the suspended atoms, which they said was analogous to adjusting the sensitivity of Einstein\u2019s theoretical springs, this fuzziness increased or decreased as the atoms became more or less \u201cspatially extensive.\u201d<\/p>\n

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After achieving the right balance, the team performed several runs of their idealized double-slit experiment designed to determine who was right, Einstein or Bohr. When the \u201cspring-like\u201d suspension lasers holding the atoms in place were turned off, the atoms became \u201cmore fuzzy\u201d and quickly fell due to gravity. In the millionth of a second before they fell, when the atoms were essentially floating \u201cin free space,\u201d the team used extremely sensitive tools to measure them. As Bohr predicted, one could observe a photon\u2019s wave-like nature or its particle nature, but one could not \u2018see\u2019 both at the same time.<\/p>\n

The study\u2019s first author, Vitaly Fedoseev, said that by proving Einstein wrong and Bohr right, they showed the fuzziness of the atoms was what mattered and the springs \u201cdo not matter.\u201d As a result, Fedoseev said, \u201cone has to use a more profound description, which uses quantum correlations between photons and atoms.\u201d<\/p>\n

In the statement\u2019s conclusion, Ketterle said that by creating an \u201cidealized Gedanken experiment,\u201d they have once again shown the dual nature of light. More importantly, the MIT team\u2019s experiments settled a nearly 100-year-old debate using single atoms and single photons they believe would have almost surely impressed the arguing visionaries.<\/p>\n

\u201cEinstein and Bohr would have never thought that this is possible,\u201d Ketterle said.<\/p>\n

The study, \u201cCoherent and incoherent light scattering by single-atom wavepackets<\/a>,\u201d was published in Physical Review Letters.<\/p>\n

Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on <\/strong>X<\/strong><\/a>, learn about his books at <\/strong>plainfiction.com<\/strong><\/a>, or email him directly at <\/strong>christopher@thedebrief.org<\/strong><\/a>.<\/p>\n

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