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Frontiers of Science Lecture — Cloaking: Where Science Meets Science Fiction

Lecturer: Graeme W. Milton, distinguished professor of mathematics, University of Utah

Date: Wednesday, March 10, 2010

Time: 7:30 p.m.

Place: Aline Wilmot Skaggs Biology Building Auditorium, University of Utah


Graeme W. Milton, distinguished professor of mathematics, and colleagues at the University of Utah have developed a new cloaking method that someday might shield submarines from sonar, planes from radar, buildings from earthquakes, and oil rigs and coastal structures from tsunamis.

Milton will discuss the new cloaking technology during a free public lecture at the University of Utah.

Cloaking involves making an object partly or completely invisible to incoming waves such as sound waves, sea waves or seismic waves, but usually electromagnetic waves such as visible light, microwaves, infrared light, radio and TV waves.

“Camouflage and stealth technology achieve partial invisibility, but can one achieve true invisibility from all visible light?” asks Milton.

In recent years, scientists devised and tested various cloaking schemes. They acknowledge practical optical cloaking for invisibility is many years away. Experiments so far have been limited to certain wavelengths such as microwaves and infrared light, and every method tried so far has limitations.

However, compared with passive cloaking by substances known as metamaterials, the new method – which involves generating waves to protect or cloak an object from other waves – can cloak from a broader band of wavelengths, Milton says.

“The problem with metamaterials is that their behavior depends strongly on the frequency you are trying to cloak from,” he adds. “So it is difficult to obtain broadband cloaking. Maybe you’d be invisible to red light, but people would see you in blue light.”

In contrast, Milton says the new cloaking technology causes “destructive interference,” which occurs when two pebbles are thrown in a pond. In places where wave crests meet, the waves add up and the crests are taller. Where troughs meet, the troughs are deeper. But where crests cross troughs, the water is still because they cancel each other out.

For example, imagine incoming waves as water waves, and envision breakwater cloaking devices that would generate waves to create a quiet zone that would protect oil rigs or specific coastal structures against incoming tsunami waves. Or imagine cloaking devices around buildings to generate vibrations to neutralize incoming seismic waves.

A video showing an object uncloaked and cloaked as a wave passes may be seen and downloaded from

The Frontiers of Science lecture series is sponsored by the College of Science and the College of Mines and Earth Sciences. Lectures are free and open to the public, but tickets are required to guarantee seating. Contact the College of Science at (801) 581-6958 or visit to reserve tickets for the event.