## Ulster Festival- University of Ulster

Posted by Tom Estes on Sunday, June 24, 2012

Tom Estes – Live Art Performance

- In The Glass Box -

The Ulster Festival of Art & Design

March 20th 2012

The University of Ulster- Belfast

Ah, spring! This season brings increasing daylight, warming temperatures, and the rebirth of flora and fauna. People have recognized the Vernal Equinox for thousands of years as it hails the start of Spring. This year The Vernal Equinox began in the Northern hemisphere on March 20th. As a visiting lecturer at The University of Ulster Tom Estes decided to celebrate the Vernal Equinox by creating a Live Art Performance for The Ulster Festival of Art & Design.

The aim of the project was to use the Sun’s rays to make a cup of tea by means of this ‘Parabolic Solar Kettle’. Using an old umbrella and a bit of aluminium foil Estes created a Parabolic Curve as a reflector or a ‘Parabolic Solar Kettle’ while discussing his practice with students and members of the public. The project was inspired by The Vernal Equinox but also by local Neolithic monuments like Newgrange (Irish: Sí an Bhrú) because it is aligned with the rising sun on the winter solstice, which on that one day of the year floods its stone room with light .

Although New Grange is aligned to the Winter Solstice, there is no shortage of rituals and traditions surrounding the coming of spring.The early Egyptians built the Great Sphinx so that it points directly toward the rising Sun on the day of the Vernal Equinox. The first day of spring also marks the beginning of Nowruz, the Persian New Year. The celebration lasts 13 days and is rooted in the 3,000-year-old tradition of Zorastrianism.

Far from being an arbitrary indicator of the changing seasons, March 20 (March 21 in some years) is significant for astronomical reasons. On March 20, 2012, the Sun crosses directly over the Earth's equator. This moment is known as the vernal equinox in the Northern Hemisphere. For the Southern Hemisphere, this is the moment of the autumnal equinox. The word equinox is derived from the Latin words meaning “equal night.” The spring and fall equinoxes are the only dates with equal daylight and dark as the Sun crosses the celestial equator. At the equinoxes, the tilt of Earth relative to the Sun is zero, which means that Earth’s axis neither points toward nor away from the Sun.

In order to create a ‘Parabolic Solar Kettle’ Estes had to create a Parabolic Curve. Parabolic geometry is well known, and it was probably the very first type of solar cooker. In mathematics, a parabola plural parabolae or parabolas, from the Greek παραβολή) is a conic section, created from the intersection of a right circular conical surface and a plane parallel to a generating straight line of that surface. Another way to generate a parabola is to examine a point (the focus) and a line (the directix) on a plane. The locus of points in that plane that are equidistant from both the line and point is a parabola.

The parabolic shape focuses the sun's rays into one point; called the focal point. However, it is not the sun’s heat that heats the water, nor is it the outside ambient temperature, though this can somewhat affect the rate or time required to boil, but rather it is the suns rays that are converted to heat energy that heat the water; and this heat energy is then retained by the container and the water by the means of a covering or lid. This occurs in much the same way that a greenhouse (or a Glass Box) retains heat or a car with its windows rolled up. An effective solar cooker will use the energy of the sun to heat the vessel and efficiently retain the energy (heat) for maximum effectiveness. In order to make the water boil the solar heating had to be done by means of the suns UV rays. The solar kettle lets the UV light rays in and then converts them to longer infrared light rays that cannot escape. Infrared radiation has the right energy to make the water molecules vibrate vigorously and heat up.

In the parabolic shape the line perpendicular to the directrix and passing through the focus (that is, the line that splits the parabola through the middle) is called the "axis of symmetry". The point on the axis of symmetry that intersects the parabola is called the "vertex", and it is the point where the curvature is greatest. Parabolas can open up, down, left, right, or in some other arbitrary direction. Any parabola can be repositioned and rescaled to fit exactly on any other parabola — that is, all parabolas are similar. The parabola has many important applications. They are frequently used in physics, engineering, and many other areas. In algebraic geometry, the parabola is generalized by the rational normal curves, which have coordinates the standard parabola is the case and the case is known as the twisted cubic. A further generalization is given by the Veronese variety, when there is more than one input variable.

In the theory of quadratic forms, the parabola is the graph of the quadratic form (or other scalings), while the elliptic paraboloid is the graph of the positive-definite quadratic form (or scalings) and the hyperbolic paraboloid is the graph of the indefinite quadratic form Generalizations to more variables yield further such objects. The curves for other values of p are traditionally referred to as the higher parabolas, and were originally treated implicitly, in the form for p and q both positive integers, in which form they are seen to be algebraic curves. These correspond to the explicit formula for a positive fractional power of x. Negative fractional powers correspond to the implicit equation and are traditionally referred to as higher hyperbolas. Analytically, x can also be raised to an irrational power (for positive values of x); the analytic properties are analogous to when x is raised to rational powers, but the resulting curve is no longer algebraic, and cannot be analyzed via algebraic geometry.

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