1 July 2020, 6:02 pm
www.timesofisrael.com/blowing-bubbles-israeli-physicists-accidentally-make-breakthrough-on-light/
Technion researchers demonstrate branched flow, a
‘beautiful’ process that scientists have written about for years, but
never seen
Branched flow, with bubbles in the background, as observed through a
microscope at the Technion - Israel Institute of Technology (courtesy of
the Technion - Israel Institute of Technology)
Branched flow, as observed through a microscope at the Technion - Israel
Institute of Technology (courtesy of the Technion - Israel Institute of
Technology)
In an accidental breakthrough made while blowing kids’ soap bubbles,
Israeli scientists have observed light behaving in a “beautiful” manner
never before seen by the human eye.
They captured the process on camera and wrote an academic paper
declaring themselves the first people to see a physical phenomenon
called “branched flow” in action, which will be the cover story in
Thursday’s edition of the renowned journal Nature.
“There is nothing more exciting than discovering something new, and
this is the first demonstration of this phenomenon with light waves,”
said Uri Sivan, president of the Technion – Israel Institute of
Technology. Anatoly Patsyk, a PhD student involved in the discovery,
called it “another one of nature’s surprises.”
Technion physics professor Moti Segev told The Times of Israel that he had no idea, at first, what he was looking at.
“We were shining light into bubbles, and started to notice a very
pretty and peculiar scattering process, in which the light splits into
branches, like branches of a tree,” he said.
They had no idea why this was happening.
“I thought maybe it’s accidental, but little by little we unraveled
the physics and then saw it was related to branched flow,” said Segev.
This process was discovered in 2001, but the closest scientists
got to witnessing it was through an electron microscope, which doesn’t
provide an actual view of the target being examined, but rather uses
electrons to probe the target and construct an image of what is
happening. Only limited scientific exploration is possible from this
image.
Segev said his lab team was amazed when it dawned on them that what
they were looking at — mostly through a magnifying glass or microscope,
but also visible to a point through the naked eye — was branched flow.
“The important moment was when we understood what we had in front
of us,” he commented. “Before that, it was the beautiful outcome of an
experiment, but then it became meaningful in scientific terms.”
The researchers have since solved the initial question that prompted
them to start blowing bubbles, which was to do with how light behaves
around curves, but Segev said that their accidental breakthrough proved
“far more exciting.”
He said that it will lead to a new area of physics, and believes that
the light from branched flow will be useful in medical diagnosis, as he
thinks it could bring about more pinpointed examination of blood
vessels and veins, and could also be developed to “steer the flow of
liquid” inside the body to remedy some health issues.
Segev said that the surprising thing about the breakthrough is how
easy it was to observe branched flow. His team was shining light,
through an optical fiber, into the membrane of a bubble, meaning
directly into the soapy substance that forms the bubble and not into the
air inside the bubble.
“Had anybody inserted a light into the wall of a soap bubble before
now, they would have seen it but no one had reason to do so,” he
commented.
Branched flow is an unusual form of light scattering. When waves of
all types travel and things get in their way, they scatter. The manner
of the scattering depends on the nature of the obstacle. “Normally the
scattering is pretty much uniform,” Segev explained, “but what is unique
here is that the length of the waves is smaller than the wave of the
obstacle, and that the obstacle is smooth.”
He said that people wouldn’t be able to see branched flow at home, as
they would need a way to hold a bubble still without bursting it and a
fiber-optic light, but said that science enthusiasts, with some lab
equipment could do so easily.
“In principle we could teach a high school student to do it,” he commented.
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