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Today's Topics:
1. Team confirm the wave-particle duality of light holds up,
even on the most fundamental quantum scales (Stephen Loosley)
----------------------------------------------------------------------
Message: 1
Date: Sun, 03 Aug 2025 22:10:55 +0930
From: Stephen Loosley <[email protected]>
To: "link" <[email protected]>
Subject: [LINK] Team confirm the wave-particle duality of light holds
up, even on the most fundamental quantum scales
Message-ID: <[email protected]>
Content-Type: text/plain; charset="UTF-8"
Twist on Famous Double-Slit Experiment Deals a Blow to Einstein?s Quantum Doubts
A groundbreaking experiment demonstrates yet again that light exists both as a
wave and a particle in the quantum world?but we can?t see both at the same time.
"The team confirmed that the wave-particle duality of light?with all its
paradoxical properties?holds up even on the most fundamental quantum scales.
By Gayoung Lee Published August 1, 2025 | Comments (29) |
https://gizmodo.com/twist-on-famous-double-slit-experiment-deals-a-blow-to-einsteins-quantum-doubts-2000637877
In an experimental breakthrough, physicists replicated a key quantum experiment
on the atomic level.
Albert Einstein famously disliked quantum theory?s understanding that physical
objects, including light, exist as both a particle and a wave, and that this
duality could not be simultaneously observed. But a new, simple iteration of a
foundational quantum experiment offers the most conclusive, direct evidence yet
that Einstein may have been wrong.
In a recent paper for Physical Review Letters, MIT scientists successfully
replicated the double-slit experiment on the atomic scale, allowing for an
unprecedented level of empirical precision. By using supercold atoms as ?slits?
for light to pass through, the team confirmed that the wave-particle duality of
light?with all its paradoxical properties?holds up even on the most fundamental
quantum scales.
The double-slit experiment, first performed in 1801 by British physicist Thomas
Young, illustrates the dual nature of light in the quantum world. When you
shine a beam of light?photon ?particles? following a direct path?through two
parallel slits on a screen, what appears on the other side is an interference
pattern resembling the union of two ripples in a pond, like a ?wave.? But if
you try to catch this mysterious transition in action by peering into the slit,
you lose the interference pattern.
Niels Bohr, Einstein?s main opponent in this debate, referred to this result as
complementarity, the idea that it?s impossible to simultaneously measure
complementary properties of a quantum system. But Einstein surmised that, if a
paper-thin slit held in place by a spring was struck with light, the individual
photons would shake the spring in a particle-like manner. That way, we could
catch the duality of light in action.
Niels Bohr Albert Einstein Quantum Debate
To test this hypothesis, the MIT team stripped down their experimental setup to
the scale of single atoms, which they cooled down to microkelvin temperatures
(for context, one kelvin is equivalent to -460 degrees Fahrenheit or -272
degrees Celsius).
They used lasers to arrange more than 10,000 atoms into a neat, crystal-like
configuration. This highly controlled environment allowed the researchers to
adjust each atom?s ?fuzziness,? or the certainty of its location. Simply, a
fuzzier atom increases the probability that a photon passing through will
exhibit particle-like behavior.
?These single atoms are like the smallest slits you could possibly build,?
explained Wolfgang Ketterle, the study?s senior author, to MIT News.
By repeatedly bombarding the atomic ?slits? with photons, Ketterle, a 2001
Nobel laureate, and his team were able to record the diffraction pattern from
the photons scattering off the atomic slits.
What they found, unsurprisingly, was that Bohr was correct. The more they
zoomed in on the path of an individual photon, the weaker the diffraction
pattern became, confirming we can?t observe light as both a wave and a particle
simultaneously.
They also tried shutting off the lasers holding the atoms in place?the ?spring?
for their setup. Even then, it was impossible to track a photon?s path without
disrupting the wave-like interference pattern.
?In many descriptions, the springs play a major role. But we show, no, the
springs do not matter here; what matters is only the fuzziness of the atoms,?
explained Vitaly Fedoseev, study lead author, also to MIT News.
?Therefore, one has to use a more profound description [like Bohr?s
complementarity], which uses quantum correlations between photons and atoms.?
Einstein is sometimes accused of hating quantum physics. This isn?t necessarily
true.
Einstein believed quantum theory needed more work, especially regarding its
overreliance on randomness?but he never completely rejected its validity.
As he wrote in a famous letter to physicist Max Born, quantum mechanics is
?certainly imposing,? but his instinct is that it?s ?not yet the real
thing?[God] is not playing dice.?
Einstein had a lot of questions about quantum mechanics, many of which remain
unanswered.
And as the Einstein-Bohr debate?and the new MIT finding?illustrates, his
rigorous, provocative challenges to what physicists take for granted continue
to advance our understanding of the weird, paradoxical world of quantum
mechanics.
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