In the comics, Thor spins his hammer very fast and hurls it into the air, allowing him to be pulled into flight. Could you make a machine that 鈥渇lew鈥� using such a principle?
Alex McDowell
London, UK
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When we jump, our legs propel our upper body upwards and it pulls our legs up with it. Hence our legs are, briefly, pulled into flight.
Cyrano de Bergerac proposed, in A Voyage to the Moon (published in 1656), sitting on an iron plate and repeatedly throwing magnets up, so they would pull the plate up, and then catching them.
Thor and Cyrano鈥檚 methods would work, in principle, when on the ground. But, once airborne, the recoil from throwing the object would cancel out the 鈥減ull鈥� from it (whether it were the hammer or the magnets). If Thor spun his hammer, he would spin the other way when he was airborne.
In space, you can, of course, propel yourself by throwing an object in the opposite direction of travel 鈥� but then that object is lost! In the Doctor Who television serial Four to Doomsday (1982), the Doctor is floating in space between a spaceship and the Tardis. To get to the Tardis, he throws a cricket ball at the spaceship and catches it when it bounces back.
Of course, the recoil alone would have propelled him to the Tardis, but the makers got it wrong and he didn鈥檛 move until he caught the ball. Catching the ball would have got him there quicker and given him the chance to use the ball again to increase speed or for course correction.
Stephen Johnson
Eugene, Oregon, US
Yes, it is possible to make a flying machine based on the principles of Thor鈥檚 hammer. In fact, three such machines already exist.
The first is the shot put. In order to make the shot put fly, the thrower spins in the ring for approximately 540 degrees to increase the acceleration of the ball prior to release. If you look at the of world-record holder Ryan Crouser, you will see that he bears an amazing resemblance to current romantic depictions of the Norse demigod Thor.
The second and even more impressive flying machine propelled by rotation is the discus. Because of its weight, its much better aerodynamics and the speed of rotation generated in its slightly bigger throwing circle, it really does look like it is heading for orbit when launched. For the most dynamic and elegant example of this technique, see the current . If Thor had a sister, she would probably be stylised to look like Allman.
The third example is, of course, the hammer, which allows an even longer set of rotations before it takes flight. Since Thor is a demigod, and since the laws of physics might be different for someone from Asgard, he is able to go along for the ride and also ignore the effect of gravity.
Michael Horwood
Exeter, Devon, UK
Yes, but Thor would need to anchor himself to the ground while getting the hammer spinning before pulling the release at the critical moment.
Pat French
Telford, Shropshire, UK
We鈥檝e already done it (a bit).
Of course, an immortal being just might be using effects that we mortals don鈥檛 entirely understand. Thor apparently uses muscle power to build up angular momentum by swinging his hammer in a circle in the same way that the biblical David powered up his slingshot by twirling it around his head. David then released one of the restraining cords of his sling, thereby allowing centrifugal (a word that literally means 鈥渇leeing the centre鈥�) force to convert the angular (circular) momentum of his stone into the linear momentum of flight at the same time as releasing it.
Thor, however, appears to swing his hammer in a vertical plane in order to achieve take-off. Quite how he converts its angular momentum into the linear momentum of flight without letting go is unclear. He could jump at the right moment, freeing his boots from the friction that stopped him turning somersaults, but that would mean he had the stickiest soles imaginable. Also, he must have a hammer that is sufficiently dense that it would punch a hole in the pavement and then sink out of sight rather than take flight.
On the other hand, spaceships tend to take off in the direction of Earth鈥檚 rotation, thereby tapping into the huge planetary momentum. They also sometimes accelerate during their journey by slingshotting around planets. They use the planets鈥� gravity to develop added angular momentum. It 鈥渨hips鈥� them around a partial orbit. They then use their newly increased momentum to escape, but there is a net overall gain. Theoretically, the planet or moon that gifted the craft extra energy would slow down imperceptibly.
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