Levitating Objects Using Heat Achieved By Scientists

Levitating macroscopic objects has been successfully achieved in a laboratory: ceramic, ice particles, lint strands, among others, were the materials that were made to ‘float in thin air’. The findings are published in the journal Applied Physics Letters.

Levitation of macroscopic objects between warm and cold plates in a vacuum. Photo credits: Chicago Jean Lachat.

A plethora of objects, from ceramic to glass bubbles, have been made to float in a vacuum chamber. Levitating is not exactly new to science—researchers have, in the past, succeeded in making certain materials ‘float’. But, the new findings proved to be far ahead its predecessors.

A team of scientists from the University of Chicago, led by two undergraduate physics students, namely Frankie Fung and Mykhaylo Usatyuk, have achieved a tremendous feat: they levitated a group of objects (ceramic and polyethylene spheres, glass bubbles, ice particles, lint strands and thistle seeds) by ‘holding’ them in a vacuum chamber, in between two plates (one hot, and the other cold). The experiments were conducted in an ultracold laboratory in the Gordon Center for Integrative Science.

The experiments of Fung and Usatyuk stand out from all other similar ones carried out by other researchers: the levitation process lasted for over an hour while the duration of the previous ones amount to a few minutes only; stability of the system was achieved not only vertically, but radially as well; a temperature gradient was used instead of a light and/or magnetic fields, the latter constituting certain limitations. The researcher in whose lab the experiments were performed, Cheng Chin, explains that magnetic levitation is only possible for magnetic objects while light fields can only work with objects that can be subjected to light polarisation. The new research, on the other hand, allows for the levitation of other objects, as named above.

The methodology through which these results were achieved entailed a steep temperature gradient in the system: the top plate, a nitrogen-filled stainless steel cylinder, was of an extremely low temperature while the bottom copper plate was kept at room temperature. This large gap in temperature caused an unbroken flow of heat from the warm plate to the cold plate, such that the particles floated continuously. This was possible because the large gradient created a “force that balanced gravity”, leading to great stability around the levitating objects, explains lead author Fung.

Levitation of lint. Photo credits: Chin Lab.

For the system to work in a stable manner, the size and spacing of the plates need to be of precise values. Furthermore, the temperature gradient has to be maintained within a certain range; otherwise, a mere one degree deviation will impact negatively on the system’s stability.

“Only within a narrow range of pressure, temperature gradient and plate geometric factors can we reach stable and long levitation,” Chin said. “Different particles also require fine adjustment of the parameters.”

This study is hoped to boost research in microgravity environments, like in orbiting spacecrafts. Levitation of particles in vacuums is also associated with fields like astro-chemistry and space exploration. The applications of the apparatus might extend to nuclear reactor safety techniques as well.

Now, the authors want to levitate macroscopic objects larger than a centimetre in size.

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