How many inventors does it take to change a lightbulb? According to US Patent No. 6,826,983 B1, which describes an automatic lightbulb changer, the answer is zero — although one could argue it still requires one inventor to come up with the device. The changer not only removes and replaces the bulb but can also detect that a bulb is burnt out and needs changing to begin with.

Although the contraption sounds quite funny, and the inventor indeed sees one of its uses as a novelty item, how to minimize the downtime of lighting fixtures can be a real problem. It is often solved by exchanging bulbs before they burn out, creating waste. Luckily, the longer lifetimes of modern LEDs alleviate this issue, but probably also render the patented lightbulb changer obsolete.

This kind of thinking lies behind the Ig Nobel Prize, which celebrates research that first makes one laugh and then think, and which is awarded again this month. The engineering and technology categories of the Ig Nobel Prize have in the past honoured inventions, but we wanted to highlight some more patents that are grounded in physics and can make you both laugh and think.

In 2000, physicist Andrew Geim was awarded an Ig Nobel Prize for levitating a frog. But maybe he wasn’t thinking big enough, certainly not compared to US Patent No. 4,457,509. It was filed in 1984 and describes a levitationarium — essentially a room for floating humans. Unlike Geim’s magnetic approach, this patent describes a blowing propeller that produces a suction flow through a specially designed air passage, which ultimately levitates a person. The inventor also remembered to include a spectator gallery in the design.

The name levitationarium did not stick, maybe because it sounds like a Victorian sideshow attraction. But vertical wind tunnels, as they are more commonly called today, have been used in aerodynamics research and to train skydivers as they can mimic the freefall phase of a sky dive. Even those who aren’t preparing to jump out of an aircraft can experience so-called body flight in a recreational wind tunnel.

A decade before cloaking devices moved from the realm of science fiction into a field of scientific research, US Patent No. 5,307,162 described an optoelectronic system for controlled camouflage. It consists of a shield that obscures a scene, which is recorded by sensors that feed back the live image to be displayed on the shield.

A variation of this approach is more likely to be used in a heist movie to fool a security system than to feature in a scientific cloaking paper. The typical approach in research uses a different idea of cloaking, in which light is moved around an object and restored into a wavefront that shows no sign of interacting with the object. Unlike the patented optoelectronic version, these cloaking devices are usually limited to a narrow range of wavelengths and other operating parameters.

Another invention that must have felt like science fiction when it was filed in 1993 is the ‘statite’ — a payload that is kept in a stationary position close to a celestial body with the help of light pressure (US Patent No. 5,183,225). The inventor intended it to complement geostationary satellites, so the potential use cases are clear. But the idea that solar radiation pressure could have a noticeable impact on a massive object must have seemed outlandish at the time and still defies many peoples’ intuition.

Yet solar-powered space flight is now a serious topic of research. NASA’s ACS3 mission, for example, is developing solar sail propulsion and has already completed a successful test of launching and unfolding the sails in orbit last year. ACS3 is part of NASA’s efforts towards smaller satellites, such as SmallSats and CubeSats, which are lightweight enough to be propelled using solar sails.

Like the research that has won and will win the Ig Nobel Prize, some patents make one smile, but on second thoughts they may turn out to be much closer to the topics physicists and engineers spend their days thinking about.