Spin doctors create fastest rotating man-made object

ORIGINAL: U of St Andrews

28 August 2013

A team of researchers at the University of St Andrews has created the world’s fastest spinning man-made object.

Dr Yoshihiki Arita, Dr Michael Mazilu and Professor Kishan Dholakia of the School of Physics and Astronomy at the University of St Andrews were able to levitate and spin a microscopic sphere, purely using laser light in a vacuum, briefly up to 600 million RPM before it broke apart.

This speed is half a million times faster than the spin speed of a domestic washing machine and more than a thousand times faster than a dental drill.

The work is published today (28 August) in the international journal Nature Communications.

Although there is much international research exploring what happens at the boundary between classical physics and quantum physics, most of this experimental work uses atoms or molecules. The St Andrews team aimed to understand what happened for larger objects containing a million million atoms or more.

To do this they manufactured a microscopic sphere of calcium carbonate only 4 millionths of a metre in diameter. The team then used the miniscule forces of laser light to hold the sphere with the radiation pressure of light - rather like levitating a beach ball with a jet of water.

They exploited the property of polarisation of the laser light that changed as the light passed through the levitating sphere, exerting a small twist or torque.

Placing the sphere in vacuum largely removed the drag (friction) due to any gas environment, allowing the team to achieve the very high rotation rates.

In addition to the rotation, the team observed a “compression” of the excursions or “wobble” of the particle in all three dimensions, which can be understood as a “cooling” of the motion. Essentially the particle behaved like the world’s smallest gyroscope, stabilising its motion around the axis of rotation.

Dr Yoshihiko Arita said: “This is an exciting, thought-provoking experiment that pushes the boundary of our understanding of rotating bodies. 

“I am intrigued with the prospect of extending this to multiple trapped particles and rotating systems. We may even be able to shed light on the area of quantum friction – that is – does quantum mechanics put the brakes on the motion or spinning particle even though we are in a near perfect vacuum with no other apparent sources of friction?”

Dr Michael Mazilu, a newly appointed lecturer in the School of Physics and Astronomy, said: “This system poses fascinating questions with regard to thermodynamics and is a challenging system to model theoretically. The rotation rate is so fast that the angular acceleration at the sphere surface is 1 billion times that of gravity on the Earth surface– it’s amazing that the centrifugal forces do not cause the sphere to disintegrate!”

Professor Kishan Dholakia said: “The team has performed a real breakthrough piece of work that we believe will resonate with the international community. In addition to the exciting fundamental physics aspects, this experiment will allow us to probe the nature of friction in very small systems, which has relevance to the next generation of microscopic devices. And it’s always good to hold a “world record” - even if for only a while!”

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Fish Are Warmer, Faster, Stronger: Unexpected Benefits of Living in a Changing Climate, Biologists Find

ORIGINAL: Science Daily

Zebrafish embryos, taken 28 hours after fertilization (a little over a third of the way through embryonic development). (Credit: Ian Johnston)

ScienceDaily (Aug. 14, 2012) — New research by McMaster University biologist Graham Scott suggests that growing up at warmer temperatures helps some aquatic animals cope with climate change, raising questions about the limits of adaptation.

Working with Ian Johnston at the University of St Andrews in Scotland, Scott has found that raising zebrafish at warmer temperatures as embryos actually improves their ability to adjust to both higher and lower temperatures as adults.

Their research shows the fish are hardier after being raised in a warm-water nursery, and raises the question of how far the temperature can rise before the advantage becomes a liability, as inevitably it will, Scott says.

"What limits are there to their coping abilities? That's what we're really trying to understand," says Scott, a specialist in animals' adaptation to challenging environments. "If we want to appreciate how the natural world is affected by climate change, that's what we need to know."

The research appears in the Proceedings of the National Academy of Sciences.

Zebrafish are native to freshwater habitats of Southern Asia, and over their lives can experience a range of temperatures from almost 40°C to nearly freezing. The fish under study were raised across the range of temperatures they would normally experience in their natural breeding season (22°C to 32°C).

The biology of zebrafish -- especially their short gestation period -- makes them ideal research subjects.

Scott and Johnston found that when embryos raised in warm water experienced temperature variation as adults, they could swim faster, their muscle was better suited for aerobic exercise, and they expressed at higher levels many of the genes that contribute to exercise performance.

The improvements were true for the adult fish in warmer and colder water alike -- a finding that surprised the researchers.

"We thought that they might do better under warmer conditions because they grew up in warmer conditions. We didn't think they'd also do better under colder conditions, but they did."