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From the 4 th Dimension An introductory lecture that describes the mathematics behind Field Dynamics. What do you see? Creating a 4D geometry Thinking outside the 4D box Field dynamics. What do you see?.
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From the 4th DimensionAn introductory lecture that describes the mathematics behind Field Dynamics • What do you see? • Creating a 4D geometry • Thinking outside the 4D box • Field dynamics
What do you see? Look at the stars. Where do they appear to be? They all appear to lie on a surface. You can’t distinguish between objects nearby and far away. The signals that reach your eye come from very different times – some come from many centuries ago.
What do you see? In absence of relative spatial information, like color and texture, you don’t know where an object is.
What do you see? Sometimes perception fools you…
What do you see? An event occurs at time –t. Age is measured in the negative t direction and time t moves in the positive t direction. An event reaches your eye at time t’. The signal from the event travels towards you at speed c. The relative time between the event and when you see it is t + t’. The distance traveled is r = c (t + t’).
What do you see? – t t = 0 t’ ct ct’ r The communication line ct’ = r – ct You don’t directly measure the time of an event, its speed, or its distance from you. You only record the time t’ it reaches you.
Creating a 4D geometry Goal: To Create an Ordinary 4D Geometry Question: What is an Ordinary 4D geometry? Answer: A Geometry that Bases its Length on the Pythagorean Theorem
Creating a 4D geometry b a – b c c2 = a2 + b2 a The Pythagorean Theorem uses area = base x heightIt doesn’t make sense when a coordinate is temporal.
Creating a 4D geometry The 4th dimension of an ordinary 4D geometry is created using the communication line. The time t on the communication line is rotated 90 degrees to create a 4th perpendicular coordinate. To do this, we first need to review complex numbers.
Creating a 4D geometry Historical perspective Geometry once consisted of only zero and positive numbers. The construction of geometric shapes requires only line segments. When the coordinate system was introduced the need arose for rays. Rays accompanied an acceptance of negative numbers and complex numbers.
Creating a 4D geometry y R = (x, y) x The Ray
Creating a 4D geometry aR R R2 R R1 R1 + R2 = (x1, y1) + (x2, y2) = (x1 + x2, y1 + y2) aR = a(x, y) = (ax, ay) Rays can be added and lengthened in any order. They obey the five rules of ordinary arithmetic (associative rules of addition and multiplication, commutative rules of addition and multiplication, distributive rule). Thus, rays can be manipulated like numbers. This is the foundation of real vector algebra.
Creating a 4D geometry iR = (–y, x) y R = (x, y) x Rays can be rotated, added, and lengthening in any order. They satisfy the five rules of arithmetic. This produces the general operation (a + ib)(x, y) i means rotate 90 degrees It’s standard to write (x, 0) as simply x and (0, y) = i(y, 0) as simply iy so a ray (x, y) can be viewed as (x, y) = (x, 0) + (0, y) = x + iy This is the foundation of complex algebra and this is what allows the operation i to be regarded as a number.
Creating a 4D geometry x4 R = (r, x4) = ct’ r ….now we rotate time and create the 4th geometric coordinate. ct’ = r – ct = r + i2ct = r + ix4 x4 = ict
Creating a 4D geometry x4 R = (r, x4) = ct’ r This development showed that physical reality can be represented by an ordinary 4D geometry. We saw why the Pythagorean Theorem can be used with a temporal coordinate, and found how geometric time x4, conventional time t, and the measurement t’ are related to each other.
Thinking outside the 4D box The faces of a 4D cube are 3D cubes. The faces consist of 8 3D cubes – a positive and negative cube for each axis.
Thinking outside the 4D box The two most common 3D vector operations are the dot product and the cross product. The dot product works in 4D, too. Here’s how the right-hand rule and the cross product extend to 4D. In 3D, the normal to a surface is In 4D, the normal to a volume is
Field dynamics The ordinary 4D geometry discussed in this talk is the foundation of field dynamics.
Field dynamics The Problem-Solving Process inField Dynamics • Formulation Set-up: A constitutive topology is set up. • particles, boundary conditions, types of interactions (electro-mechanical) • order-reduction (irreversible processes) Transition: The system is drawn (free-body diagram). • Solution Equation: Governing equations are listed. Answer: Equations are solved. Knowledge: Insight is gained.
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