The Phenomena of Special Relativity
as a Result of the Curved Expanding Universe

This is a interactive presentation of the Proper Time Adjusted Special Relativity theory proposed in this site. In the text that follows, some words are links, and when you click on them things happen in the applet. Most of them work as toggles. It should be self explanatory.

We will try to show that the phenomena of Special Relativity are produced by the curved expanding universe that was proposed for the first time as a solution to the equations of General Relativity.

Let's start with the Lorentz transformation. The axes of the Moving Body as calculated by the Lorentz transformation (for c = 1 and v = 0.6) are these. The left axis is the worldline of the Moving Body (its t axis), and at t = 10 the Stationary Body is here and the Moving Body is here.

However, its proper time, as indicated by the gray number beside it, is t' = 8. Now, let's see what will happen if we place the Moving Body at the time coordinate given by its proper time. That is, instead of it being at t = 10, we place it at t' = 8. We will call this "adjusted" Moving Body. This of course defines a new worldline, this.

Now, from the Lorentz transformation, if we set x' = 0, which gives us the position of the Moving Body itself, we get the following equations of motion for the Moving Body (click here to see derivation): This equation for proper time t' is in fact the equation of an ellipse:       And the ellipse is this: Ellipse with semiaxes T (time)  and cT (space)

Let's see it on the graph (where it is a circle since c = 1). If we clear all other elements, keeping only the adjusted Moving Body, and play around with its speed, increasing or decreasing it, we see that it moves along the circle (or ellipse if we increase or decrease c from its initial value of 1). (All this happens through the equation for t', it is not "made up".)

This means that the circle (or ellipse) is indeed the space dimension along which the Moving Body moves. We can define the space dimension as the set of all points of a spacetime that coexist in a specific moment of time (see below). Another way to define it, which amounts to the same thing, is to say that the space dimension is the set of all points that can be reached in a specific time interval by moving objects of all possible velocities, from zero to infinity, or the maximum velocity allowed in the spacetime. So, when we increase or decrease the speed of the Moving Body, it essentially traces the space dimension.

Now let's toggle back on the elements that interest us. It is reasonable to put the x axis of the adjusted Moving Body perpendicular to its worldline (tangent to the circle or ellipse) like this.

Now, what is the relationship between the gray axes calculated by the Lorentz transformation, and the blue axes of the Moving Body in its "adjusted" proper time position? We see right away that the Moving Body in the "unadjusted" position can be considered a projection of the adjusted Moving Body on the dark gray line (which is the x axis of the Stationary Body), like this. (Click here to see a simple algebraic proof.)

What about the Lorentz x axis? In fact, the point that the Lorentz x axis intersects the x axis of the Stationary Body is a projection of the intersection of the blue x axis with the (light gray) x axis of the Stationary Body at t = 0. It sounds complicated, but it is simply this. (Click here to see a simple algebraic proof.)

So essentially the adjusted Moving Body and its x axis are projected on the x axis of the Stationary Body, and this produces the axes of the Lorentz transformation. And I think that this cannot be a coincidence.

You can see the formation of the normal Lorentz axes by the adjusted Lorentz axes in "real time" using the contols below.

Derivation of the Projected Coordinate System

 Blue Circle: Circular expanding spacetime Blue Axes: Coordinate system of the Moving Body according to the adjusted Lorentz transformation Gray Inclined Lines: Axes of the Moving Body as calculated on the basis of the (unadjusted) Lorentz transformation Gray Horizontal Line x axis of the Stationary Body

Continuous Play

Click the "Toggle t Axis" button to toggle on/off the formation of the Projected t Axis.

Click the "Toggle x Axis" button to toggle on/off the formation of the Projected x Axis.

Click the "Toggle t Projs" button to toggle on/off the t axis unit point projections.

Click the "Toggle x Projs" button to toggle on/off the x axis unit point projections.

Incremental Play

Click the "Set Time for t" button to reset the simulation, and to adjust the time increment so as the steps will coincide with the unit points of the t Axis. Then click the buttons t+ or t-. (If you want to change the value of c or v, do it first and then click the "Set Time for t" button, so that the applet will be able to read the new values and adjust the time step.)

Click the "Set Time for x" button to reset the simulation, and to adjust the time increment so as the steps will coincide with the unit points of the x Axis. Then click the buttons t+ or t-. (If you want to change the value of c or v, do it first and then click the "Set Time for x" button, so that the applet will be able to read the new values and adjust the time step.)

Click the "Restore" button to restore the graph to its normal state.

Now, the question is, "What do we make of this?". I would say that the expanding circle looks like a "curved" expanding spacetime, the one that was postulated as a solution to the equations of General Relativity.

Let me try to explain what I mean.

The Missing Space Dimension

Traditionally, motion graphs depict movement with lines that give the position of a body as a function of time, according to the familiar Cartesian system of representing graphically the values of a function. On the basis of this system, if we have a Stationary Body, a Moving Body with velocity v = 0.5 and a Photon with velocity c = 1, we can graph their movement as in the following diagram. The three orange lines are the worldlines of the three objects (Stationary Body, Moving Body, and Photon). Here, instead of the term "worldline", we will propose the term "timeline", in its familiar meaning of the evolution of an entity through time. Worldlines ("timelines")of Stationary Body (v = 0), Moving Body (v = 0.5) and Photon (c = 1).

However, graphs of this form do not depict a very important element, the space dimension in which these objects exist. We will use the term "spaceline" to denote this space dimension.

Thus, a spacetime is the set of all points of a space in all its moments of time, and it is depicted by the whole two-dimensional surface of the graph. A spaceline (space dimension) is the set of all points of a spacetime that coexist in a specific moment of time, i.e. all points that have the same time coordinate (isochronal line). The timeline of a spacepoint is the set of all points of a spacetime that have the same space coordinate as the spacepoint. This is also the timeline of a stationary object. Obviously, we can also define in a similar manner spacesurfaces and spacevolumes, and timesurfaces and timevolumes.

Thus a spacepoint (a space coordinate) defines a timeline (or a timesurface in a 2+1 spacetime, or a timevolume in a 3+1 spacetime) and a timepoint (a time coordinate) defines a spaceline (or a spacesurface in a 2+1 spacetime, or a spacevolume in a 3+1 spacetime). Finally, we can define the timeline of a moving object as the set of all points that satisfy the motion equation of the object.

Let us see how we can introduce the space dimension in our diagrams.

Shape of the Space Dimension

So, we can ask what is the form of the space dimension (of the spaceline) in the graph above. This form can be determined by the type of coordinates transformation that holds for a specific spacetime. We have two possible transformations, the Galileo transformation and the Lorentz transformation. In each transformation, the motion of a body is defined by a system of two simultaneous equations. For the Galileo transformation, these equations are: while for the Lorentz transformation (see derivation here) they are: The first equation gives the x coordinate of the body, and it is essentially its "timeline". The second gives its time coordinate, and is essentially the equation of the space dimension (the equation that defines the shape of the space dimension or spaceline).

The space dimension, irrespective of its equation (and therefore its shape), takes different successive positions with the passage of time, as T increases. At each one of these positions, the spaceline (space dimension) intersects the timeline of the body at a specific point, which defines the position of the body for that moment of time (the solution of a system of two simultaneous equations is depicted graphically as the intersection of the graphs of the two equations).

Galileo Transformation

In a spacetime with Galileo transformation, the equations of motion of the Stationary Body, the Moving Body and the Photon are as follows:   Stationary Body Moving Body Photon

In such a spacetime, the spaceline is a straight line perpendicular to the t axis (as evidenced by its equation t' = T, with T being a number), and it "moves upwards" with the passage of time as the value of T increases. All the points of such a spaceline have the same time coordinate (t' is equal to T for all the length of the spaceline), and because of this, time is absolute. This is depicted in the figure below.  Stationary body (blue, v = 0), Moving Body (red, v = 0.5) and Photon (yellow, c = 1), at time moments 1 and 2 in a spacetime with Galileo transformation.

The Speed of Light in the Galilean Spacetime

In such a spacetime, the speed of light is not constant for the Stationary and the Moving Body (Stationary and Moving Observer). Click here to see the measurement of the speed of light by the Moving Body. The values for t, v and c shown in the textboxes on the right are the ones that the Stationary Body sees, while those shown on the graph in orange (xg, tg, cg) are the ones measured by the Moving Body (the "g" is for "Galileo"). So, in this case, while for the Stationary Body c = 1, the Moving Body measures c to be 0.4.

In a spacetime with Galilean transformation the spaceline has the same time coordinate in all its length, and coincides with the x axis of the Stationary Body (and the Moving Body). Obviously, this can happen only if its equation is of the form t = T (T = 0, 1, 2...), a "zero degree" equation that describes a straight line perpendicular to the time axis. In any other case, different points of the spaceline will have different time coordinates (for the coordinate system of the Stationary Body).

This means they will literally be at different points of time, and of course any objects situated at these points will also be at different points of time. For instance, we could imagine a spaceline with a first degree equation t = ax + T (a special case of which is the spaceline of the Galileo transformation if a = 0). Even this simple equation will give us a spaceline that meets the time axis not perpendicularly but at an angle, and whose points will have different time coordinates. A spaceline of this form, moving upwards with the passage of time, will transect the timelines of the three objects at different time moments as measured by the Stationary Body, giving them different time coordinates in its coordinate system. (You will find a fuller treatment of this point in the article Speed of Light and the "Rate of Propagation of Time" -- opens in new window.)

Now, in a spacetime with adjusted Lorentz transformation, the equations of motion are: (See derivation here.) If we plug the velocities of the Stationary Body, the Moving Body and the Photon, we get:   Stationary Body Moving Body Photon

We pointed out previously that the second equation that defines the shape of the spaceline is the equation of an ellipse or circle, depending on the value of c (see derivation here), which "expands outwards" with the passage of time as T increases. The points of such a space dimension do not have the same time coordinate (as measured by the linear coordinate system of the Stationary Body, although they do have the same "time coordinate" in a polar coordinate system). In such a spacetime, time is "relative" because every movement of a body changes not only its space coordinate, but its time coordinate also. This is depicted in the figure below:  Stationary body (blue, v = 0), Moving Body (red, v = 0.5) and Photon (yellow, c = 1),at time moments 1 and 2 in a spacetime with adjusted Lorentz transformation.

Let us combine the two previous graphs in order to see the differences between the Galileo and the adjusted Lorentz transformation.  Stationary body (blue, v = 0), Moving Body (red, v = 0.5) and Photon (yellow, c = 1),at time moments 2 and 4 in a spacetime with Galileo transformation (orange),and a spacetime with adjusted Lorentz transformation (blue).

We can easily see that the Photon remains at the time moment it was emitted (for the coordinate system of the Stationary Body), since the Photon coordinate system is rotated by 90° for the coordinate system of the Stationary Body. Also, it is obvious that the faster the Moving Body moves, the "slower" its time will appear to the coordinate system of the Stationary Body (tending to zero as it approaches the speed of light), because the further away it moves from the Stationary Body, the more it will be able to "gain" time in relation to the time of the Stationary Body.

In fact, if we consider the equations of motion of the Moving Body, and we set the factor , equal to g the equations will become, In this form, the product vT describes the rate of movement of the body along the space dimension, and the product gT its rate of "movement" in the time dimension, that is how "fast" its time "flows".

In a Lorentz spacetime, the circular shape of the spaceline is not perceivable. Being at the position of the Stationary Body, we assume that our spaceline is straight (that our universe is "flat"), with all its points having the same time coordinate (our own), and in this way we impose linear coordinates on a curved space dimension. This is due to the fact that the curvature of the spaceline in relation to time is non perceivable and can only be deduced by the experimental evidence that lead to the formulation of the Lorentz transformation.

This means that we do not perceive the objects themselves, (the Moving Body and the Photon) situated at their correct proper time coordinate, but their projection on our x axis (their projection on our time moment), and so we "transform" the circular spaceline into a straight Galileo spaceline, something that is described by the Lorentz transformation. This produces the phenomena of length contraction and time dilation, since this projection causes a scaling of the axes of the Moving Body, changing the size of their units.

Obviously, if we went about it in the inverse way, starting from such a circular expanding space dimension, and assumed that the positions of objects are projected on the x axis of the Stationary Body, we would end up deriving the Lorentz transformation.

The Speed of Light in the Adjusted Lorentz Spacetime

In a spacetime with adjusted Lorentz transformation, the speed of light is constant for the Stationary and the Moving Body (Stationary and Moving Observer). (As we saw, this is not true for spacetimes with Galilean transformation.) Click here to see the unadjusted and adjusted Lorentz system.

The equations of motion for the Photon are: This means that the Photon's proper time is always 0, that is, it remains on the moment of time it was emitted

So the Photon is in fact here. However, as we said, the fact that an "object" (Photon or Body) is situated in a different time coordinate than our own is not perceivable, so we attribute to all objects our own time coordinate, which essentially means that we see and measure their projections on our x axis.

So, the Stationary Body sees the Photon there and so it measures c to be 1 (it sees it at x=10, and according to its clock, 10 seconds have passed). The unadjusted Moving Body sees the photon at the same point, and according to the Lorentz transformation makes these measurements, so it also measures c to be 1. And the adjusted Moving Body, sees the Photon there, and makes these measurements, so c is 1 for it too.

Spacetime curvature

So, why do I claim that the phenomena of Special Relativity are produced by the "curved expanding spacetime" that was proposed for the first time as a solution for Einstein's equations of General Relativity?

General Relativity is based on a description of curvature through the metric of spacetime. What I am proposing here is based on a description of curvature through the equation of the space dimension, that is, the second equation of motion that gives us the proper time of the body. This equation contains all the information we need. The two descriptions are not contradictory, they describe the same thing in different ways.

Generally we can say that if all the points of dimension A are projected on the same point of dimension B, then dimension A does not curve in relation to dimension B, and the plane they form is "flat". In such a case, the equation of dimension A is of the form B=n, where n is a number, the coordinate of A along B.

If the points of dimension A are projected to more than one point of dimension B, then we can say that dimension A "curves" within dimension B. (Although there is also the theoretical case that A is "inclined" in relation to B, if its equation is first degree.) If its equation is second degree or higher, then we have genuine curvature, and this equation defines clearly the shape and curvature of the dimension in all its length.

This is what happens in spacetimes with Lorentz transformation, where we have specifically the space dimension curving within the time dimension, since the points of the space dimension do not all have the same projection on the time dimension, that is, they do not all have the same time coordinate, as they do in Galilean spacetime.

The curved expanding universe of General Relativity can be likened to the surface of a sphere with increasing radius, if we reduce the dimensions to 3 (2 dimensions of space and 1 time), in order to be able to visualize this. Or, if we reduce the dimensions further (to 1 dimension of space and 1 time), it can be likened to a circle with increasing radius – and this is exactly what we have here.

And so we are at the position of the Stationary Body, stationed at one point of this circle, and in observing the spacetime around us we use a coordinate system with a straight x axis, like this. However, the space dimension on which we are stationed is not straight, it is like this, and so it does not coincide with our x axis. However, we do not perceive this, and attributing to all other objects our own time coordinate, we essentially study their projections on our x axis. This produces the phenomena of Special Relativity, like this. (Click here if you want to reset the simulation.)

 t c v
 t step c step v step
 GALILEO Space t Axis Body x Axis Photon Ph.Data
 LORENTZ Space t Axis Body x Axis Photon Ph.Data
 ADJ. LORENTZ Space t Axis Body x Axis Photon Ph.Data