Researchers use vibrations to ‘defy gravity’ and make a toy vessel float underneath a levitating layer of liquid in Physics

Scientists have demonstrated tiny boats that float upside down underneath a levitating layer of liquid in an amazing quirk of physics. Researchers in Paris were investigating the effect of vertical shaking, which can be used to suspend a layer of liquid in mid-air. Not only was the layer of liquid able to float on a suspended cushion of air, but small model boats floated on the bottom surface, thanks to intense air pressure.

This counter-intuitive behavior is a result of the constant vibrations, which change the forces acting on the floating object. This case of reverse-buoyancy might have practical uses in transporting materials through fluids and separating pollutants from water. In particular, the research took its cue from a scene in the 2007 film “Pirates of the Caribbean: At World’s End”, when Captain Jack Sparrow’s Black Pearl ship is tipped upside down.

It also takes inspiration from an eerie art installation, “Swimming Pool”, by Leandro Erlich at the 21st Century Museum of Contemporary Art, Kanazawa, Japan. Researchers were playing around and had no idea it would work. The fun thing is that it triggers reactions from people who are not scientific. It is counterintuitive. It gets people talking about science fiction and fantasy and that is very nice.

Under the action of gravity, viscous liquids in a container, such as a laboratory flask, will typically fall to the bottom of the vessel.

Flipping the container upside down will make the liquid slowly fall to the bottom in thick drops, like paint falling down a wall. But keeping the liquid in the air can be achieved by vigorous vertical shaking of the container. Scientists already knew that vibrating liquid vertically at certain frequencies and in a closed container can make it levitate above a less dense layer, such as a cushion of air.

Thanks to the vibrations, air bubbles in the lower half sink rather than rise. In their experiments, the team filled a container with a viscous liquid of either glycerol and silicon oil, and used shaking devices to vibrate the liquid vertically at high frequency. They injected air into the base of the system until the liquid started to levitate while being vibrated.

The air bubbles added to the liquid sank to the bottom of the container, as expected. But small objects, up to 7 grams in mass and 0.9 inches in length or diameter, floated upside-down on the underside of where the air and liquid met. This is because the layer of air underneath the upside down boat and floating liquid layer has very high pressure, as it is being compressed by the weight of the liquid.

This results in the boat being pushed up by the pressure underneath.

When that pressure meets an equilibrium with the downward force of gravity, the boat floats. All the while, the boat has its own buoyant force that keeps it suspended. Vertical shaking causes buoyancy to flip at the lower surface of the levitated liquid, as if the gravity there has been inverted. Buoyancy is the force exerted by a fluid that opposes the weight of an object immersed in the fluid.

The extraordinary behaviors of vibrating fluids are just a small fraction of the surprising phenomena that arise as a result of high frequency vibrations more generally. The research suggests that many remarkable phenomena arising in vibrating mechanical systems are yet to be revealed and explained, particularly at interfaces between gases and fluids. The observations defy Archimedes’ principle, in which an upward buoyant force, equal to the weight of displaced fluid, is exerted on an immersed body.

The study has been published in Nature. In August 2020, scientists can use some pretty wild forces to control objects.

To understand this, we require to look into the weirdness of quantum physics.

Optical tweezers made of lasers make use of the force of light. Now physicists have actually made a device to control objects utilizing the force of nothingness. In truth an ideal vacuum does not exist, even in void at zero temperature level, virtual particles, like photons, flicker in and out of existence. These changes engage with objects placed in vacuum and are actually boosted in magnitude as temperature level is increased.

When temperature level is increased, it triggers a quantifiable force from absolutely nothing, otherwise referred to as the Casimir effect. The scientists’ experiment happened in room temperature settings. The scientists used a small metal enclosure designed to restrict specific sort of electro-magnetic radiation, described as a microwave re-entrant cavity.

Separated from this cavity by a gap of about one micrometer was a metal-plated silicon nitride membrane acting as a Casimir spring. By using an electrostatic force, the group had the ability to control the re-entrant space with beautiful accuracy. This, in turn, permitted the scientists to manipulate the membrane with the Casimir effect that occurred when the space was sufficiently small.

When we say nothingness, we are actually describing the attractive force that emerges in between two surface areas in a vacuum, referred to as the Casimir effect.

Because of the Casimir effect in between the objects, the metal membrane, which bent back and forth, had its spring-like oscillations significantly modified. The modified oscillations was used to manipulate the homes of the membrane and re-entrant cavity system in a distinct way. The new research study has actually supplied not only a way to use it for non-contact objects adjustment, but also to determine it.

The results cover several fields, from chemistry and gravitational wave astronomy all the way down to something as basic and common as metrology, the science of measurement. If we can measure and control the Casimir effect on items, then we acquire the ability to enhance force sensitivity and decrease mechanical losses. The Casimir force was first predicted in 1948 by Dutch theoretical physicist Hendrik Casimir, and lastly demonstrated within his forecasted values in 1997.

Since then, it has actually been creating a lot more interest, not just for its own sake, but for how it might be utilized in other areas of research study. What Casimir predicted was that an attracting force would exist between two performing plates in a vacuum, due to contrasts in quantum changes in the electromagnetic field. This permitted orders of magnitudes of enhancement in force level of sensitivity and the capability to manage the mechanical state of the membrane.

Managing the gap also permitted the scientists to determine the force.

As the gap opened, the Casimir effect grew weaker, till it was at a point where it was no longer acting on the membrane. By studying the changes to the membrane, scientists could generate high accuracy measurements. It is a unique way of determining nothingness, though other techniques have actually used small rapidly moving objects to get a grip on the force applied by variations.

Other research studies have also put the force to use in less accurate ways, assisting small silicon gadgets keep their range, for example. The strategy presented here has high capacity to create extra schemes and devices by controlling the thermal Casimir effect. For example, in situ nimble programmable gadgets, engineered to control mode structures and enhance resonator losses as needed at space temperature level, might be built.

Including the development and adjustment of topological mechanical oscillators. This research is published in Nature Physics.