The binasuan is a Filipino

folk dance A folk dance is a dance that reflects the life of the people of a certain country or region. Not all ethnic dances are folk dances. For example, Ritual, ritual dances or dances of ritual origin are not considered to be folk dances. Ritual dances ...

in which the performer holds full

wine glass A wine glass is a type of Glass (drinkware), glass that is used for drinking or wine tasting, tasting wine. Most wine glasses are stemware (goblets), composed of three parts: the bowl, stem, and foot. There are a wide variety of slightly differe ...

es in each hand while performing balancing tricks. Wine may be used to fill the glasses, but other liquids may be substituted. The arms are rotated over and under the shoulder in order to keep the palms facing up so as not to spill the liquid while nevertheless allowing the

radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...

to cross over the

ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...

via

pronation Motion, the process of movement, is described using specific anatomical terminology, anatomical terms. Motion includes movement of Organ (anatomy), organs, joints, Limb (anatomy), limbs, and specific sections of the body. The terminology used de ...

. Binasuan originated in

Pangasinan Pangasinan, officially the Province of Pangasinan (, ; ; ), is a coastal Provinces of the Philippines, province in the Philippines located in the Ilocos Region of Luzon. Its capital is Lingayen, Pangasinan, Lingayen while San Carlos, Pangasi ...

and is popular at festive events such as weddings. Since the binasuan inverts the arm through rotation, it is sometimes given as a macroscopic, physical demonstration of the rotation properties of a

spin-½ In quantum mechanics, Spin (physics), spin is an intrinsic property of all elementary particles. All known fermions, the particles that constitute ordinary matter, have a spin of . The spin number describes how many symmetrical facets a partic ...

spinor In geometry and physics, spinors (pronounced "spinner" IPA ) are elements of a complex numbers, complex vector space that can be associated with Euclidean space. A spinor transforms linearly when the Euclidean space is subjected to a slight (infi ...

. As the liquid never spills, the rotation can all occur within the same plane. Upon a rotation of 2π

radian The radian, denoted by the symbol rad, is the unit of angle in the International System of Units (SI) and is the standard unit of angular measure used in many areas of mathematics. It is defined such that one radian is the angle subtended at ...

s, the elbow changes between pointing up and down. Upon a rotation of 4π

s, the palm " doubly covers" the shoulder, and the elbow points in its original direction.

References

Dances of the Philippines Culture of Pangasinan {{Philippines-stub