Knowing

epistemology, science, kinds of knowledge, methodology

Reality and relativity

As a realist I respect what is often called “common sense.” This means that our faculties of discerning reality in everyday life are basically correct. Yes, we make some mistakes, we can get fooled by a illusionist, but we almost always agree what it is that happens when things happen to us or in front […]

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What is single-value time?

Time is commonly expressed by a single value, a numerical expression of a point in time. A sequence of these points is also called time. Because of this, time is commonly considered one-dimensional. Since time actually has three dimensions, what does this single value for time represent? It must be some function of the three-dimensional

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Parametric time and space

Parametric equations are equations in terms of a single parameter. An example is the parametric equation for a circle: x = r cos(t), y = r sin(t), for a circle with radius r with rectilinear coordinates x and y. It’s best if the parameter represents a causal variable but time is often used whether or

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Speed and its inverse

Physics and transportation have many things in common, in particular they both deal with objects that move or travel. The case of an object that happens to stay in place is considered as well. An object that may move is called a body or particle or vehicle. The path, route, or course of an object

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Symmetry of space and time

The duality between space and time leads to many dual principles. For example, Fermat’s principle says that light travels between two given points along the path of shortest time. The dual to this is that light travels between given points in time along the path of shortest length in space. But as long as there

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Direction and units of magnitude

I want to clarify the statement in the previous post that “the three dimensions of direction are the same for space and time”. I have made the point that vectors in physics have various units of magnitude but direction is the same for all of them. That is accurate in the sense that directionality is

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Six-dimensional spacetime

First consider the dual to Minkowski spacetime. Recall that the invariant interval of Minkowski spacetime has one dimension of time with three dimensions of space: (ds)² = (c dt)² – (dx1)² – (dx2)² – (dx3)² = (c dt)² – (dr)² where t is the time coordinate and x1, x2, and x3 are space coordinates of

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