A Case for Absolute Velocities
The great philosopher Aristotle held
that all bodies have a preferred state of rest, such that once a body
was set in motion it would eventually slow to a stop.
Centuries later Galileo and Copernicus overturned this view, stating
there is no preferred state of motion and that the velocity of one body
only has meaning in relation to another. That is that all
velocity is relative.
Today we refer to this as the Galilean Principle of Relativity (not to
be confused with Einstein’s ‘Theory of Relativity’). It tells
us there is nothing special about the motion we experience after
all. The Earth rotates on its axis, which orbits the Sun,
which circles within the Milky Way. And our galaxy then moves
in various motions with respect to other galaxies. We really
can’t say anything about our overall state of movement, or even if such
a movement has any meaning.
But is that truly the case?
The concept of relative velocities is so well established in scientific
thought that to suggest that there may be such a thing as absolute
velocities after all must seem like lunacy. Yet a careful
analysis of our physical laws indicates otherwise. This is
not to say that Aristotle was right in his thinking. No; his
absolute velocity was just a velocity relative to Earth’s
surface. What is being discussed here is something far more
fundamental that follows unavoidably from the most basic of scientific
The Bar Room Brawl
To illustrate this, suppose you had
the ability to freeze time and then walk around and observe
things. In such a situation your world would become
completely dark because no light could be generated or reach your
eyes. So we’ll modify the situation slightly and say that a
special form of illumination comes into play that lights everything up
without disturbing anything. If you’re familiar with the
movie The Matrix,
it would be like those scenes where everyone stops
and the camera swings around them.
Now suppose you have just used your supernatural abilities to freeze
time and had then walked in on a bar-room brawl (a.k.a. a ‘pub
fight’). In this fight, two parties are located at either end
of a room behind upturned tables and are hurling projectiles, such as
bottles, cans and glasses, at each other.
Several projectiles are in the air at once, but since time is frozen,
it’s not clear which direction they are moving. Sometimes
there may be clues, such as when a bottle that had just been thrown can
be traced back to an outstretched arm. But things are not
For example, say you observe a bottle mid-way between the
parties. The arm that threw it has been retracted so there’s
no information about where it came from or which direction it is
moving. We’ll also say this situation is somehow taking place
in a vacuum so as to remove any evidence of air compression surrounding
the bottle. (after all, all great physics experiments take
place in vacuums!)
So you decide to solve the puzzle using other means. Taking
out some scientific equipment such as microscopes, interferometers,
etc., you set to work. But after studying it for an hour (in
your time) you remain perplexed. There appears to be no
information that would allow you to make a decision. Every
atom and every subatomic particle within the bottle is stone
cold. Yet you know the bottle must be moving
because it can’t
float at that position.
At this point you give up and decide to advance universal time by one
tenth of a second. Having done so you notice the bottle is
now located slightly to the left of where it was previously.
Aha! So now you know which way it is moving.
But hold on a second. How did the bottle ‘know’ where to
In science there is a principle called Cause & Effect
(C&E). What it says is that the information contained
in a situation in any point in time fully determines the situation at a
later point in time.
We often think of C&E in terms of interactions; such as if I
hit an egg with a hammer, the egg will break. In this case
the hammer-striking-the-egg is the Cause and the egg-breaking is the
Effect. But the principle also applies to simpler
situations. For example, take a stone moving through space:
in the absence of any force, the position and velocity of the stone at
one point in time will fully determine its position at any future time.
Back to the bottle. While examining it frozen in time you
could find no information about which direction it was
moving. Yet a short while later it had relocated
itself. That means, according to C&E, the information
about which direction it was moving and how fast it was moving must
somehow be contained within the situation that was frozen in
time. If this was not the case the bottle couldn't
move. The same must also be said of every atom and every
subatomic particle within the bottle. Each of them must ‘have
knowledge’ about their velocity in order to change positions from one
moment to the next. That is, the velocity must be ‘stored’
within each particle; otherwise the principle of C&E falls
What this tells us
is that velocity is a
property of matter rather than
simply a measure of how far something travels in a unit duration of
The only other possibility is that each particle contains knowledge of
its current position and its historical position a ‘short while’ ago,
in order to calculate velocity. For reasons described later,
the storing of position won’t be possible. But putting that
aside, the idea that a particle could store historical information is
even less plausible. Hence the most likely explanation is
that it stores velocity.
Some might ask, how can velocity be stored within matter? One
might just as well ask how mass and charge could be stored within
matter. The point is, we don’t know how either of these
things are stored but we do accept they are stored somehow.
The difference here is that velocity is a variable rather than static
quantity. But making a quantity variable doesn’t violate
physics laws. For example if the mass of an electron varied
with time, the only effect would be that its acceleration would also
vary with time when exposed to a constant force. Since
variable accelerations are allowed, variable masses are not
forbidden. The same argument can then be made in regards to
charge and velocity.
Zeno’s Arrow Paradox
The above scenario has a precursor in an ancient riddle known as Zeno’s
Arrow Parodox. It goes like this (somewhat reworded):
An archer has two arrows. He places one on the ground and
fires the other across a field. Once the fired arrow has left
the bow, why does it continue to move while the other stays motionless?
A close examination of both arrows before and after reveals them to be
identical in every perceivable way. And if someone were to
run alongside the fired arrow while it was in motion, he would notice no
difference between that and the other. That being the case,
why should one continue to change its location while the other doesn't?
An objection to this would be that, depending on our frame of
reference, either arrow could be considered as moving. And so
the question of why one moves rather than the other comes down to
semantics. A fair point. So let’s modify the
This time there are three arrows (A,B,C) and two archers.
Arrow A stays ‘motionless’ on the ground, and arrows B and C are fired
simultaneously in opposite directions. The question now
becomes: why does the distance between B and C enlarge more quickly
than the distance between B and A?
Notice the question no longer depends on frames of reference or
descriptions of ‘moving’ versus ‘still’, because we are looking at rates
at which distances enlarge, and these will enlarge in the same manner
regardless of our reference point.
For example, if we take arrow B as our reference point, we notice arrow
C moves away (changes its location) at double the rate of arrow
A. But if both A and C are physically identical, and
everything that surrounds them is identical, why would they update
their locations in different manner (relative to B)?
Something about them must be different.
One undeniable difference between the fired and grounded arrows is that
the fired arrows experienced a force. This caused them to
accelerate to a certain speed. But once that force ceased,
what now is the difference? Do the arrows retain a memory of
the accumulated forces applied to them? If so they would have
need to retain an infinite memory because forces can accumulate over
very long periods. In fact it can be argued that every
subatomic particle in the universe has its present location due to all
the forces that were applied to it over its lifetime, and this could be
unlimited in duration.
So yes, perhaps each ‘particle of matter’ retains a record of all the
forces that have ever been applied to it. But a much simpler
proposal is that it carries only ‘knowledge’ of its current velocity.
Relative or Absolute?
If we take it as confirmed (by
logical extension of C&E) that velocity is stored within
matter, another interesting fact follows. Up to now we are
still talking about velocity as being relative. However if
velocity is to be a property
of substance there is no way it could be
stored as a relative quantity. Because if velocity was stored
as a relative quantity it would require each particle store multiple
values of velocity – one for every other particle in existence – and
that every particle be instantaneously aware of the movements of all
others. Clearly neither of these postulates can be acceptable.
This leads to the
conclusion that velocity is stored within matter as
an absolute rather than relative quantity.
Obvious questions arise from this. The first one being: what
are these velocities with respect to? The short answer being:
not to anything. At least not to anything physical.
And nor would they need to be. That’s the whole point of
‘absolute’ after all.
Occasionally a particle might have an absolute velocity of
zero. However the occurrence will only be temporary and
accidental because particles experience force and change velocities all
the time. So again, a particle requires no reference points
or ‘frames’ to measure its velocity against, just as it requires no
reference masses or charges.
Velocities be Measured?
Another question that follows is, is
it possible to measure or even detect a particle’s absolute
velocity? The answer is: probably not. All physical
laws appear to be based entirely on velocity differences between
particles. So while all particles will have an absolute
velocity there may not be any experiments capable of detecting what
those velocities are.
For example suppose we have three particles: the first one described as
being ‘at rest’, the second moving away from the first at 1 m/s and the
third moving toward the first at 2 m/s. The actual absolute
velocities of these might respectively be 50,634,821 m/s, 50,634,822
m/s, and 50,634,819 m/s. Naturally these numbers are purely
made up. But the point here is that when these particles come
together and interact, any forces between them will be based only on
the differences between such velocities. Hence we will be unable to
detect their absolute velocities.
Of course there is more to velocity
than its magnitude or speed. Velocities also have
direction. That is, velocity is a vectored
quantity. Therefore if matter is to store information that
describes its velocity it must also store information describing its
direction. In a three-dimensional world this requires three
numbers which are described by a coordinate system. There are
several such systems to choose from. One is the cartesian,
which describes X, Y, and Z. Another is the spherical, which
describes a magnitude (R) and two latitude/longitude angles (θ and
φ). Another again is the cylindrical coordinate system.
In fact there are any number of coordinate systems we could invent to
describe a velocity in three dimensions. The most likely
however of these is the cartesian system because it is the simplest and
all the units (X,Y,Z) are equivalent in describing the same
property. Storing information in terms of another coordinate
system, such as spherical coordinates, will lead to other problems
which are too complex to delve into here.
If we take it that each particle of matter contains three pieces of
data that describe its velocity, such as X, Y and Z components, a further
requirement follows from this. Namely that the cosmos, i.e.
the empty space containing the physical universe, must have a fixed set
of directions that velocities are described against. That is
there must be a certain fixed direction that describes the ‘X’
component of velocity and likewise with Y and Z. This
requirement would also hold true for any other coordinate system.
This is not to say that we can detect such absolute directions because
the interaction between matter gives out no such clues. We
can only know the requirement for their existence follows from the
requirement of storing velocities.
What about Position?
The third question that follows is,
are there such things as absolute positions/locations and does matter
store information about its location? The answer to both is:
most likely not.
There are two reasons for saying this. Firstly, as pointed in
the cosmology chapter,
the size of physical space must
be infinitely large in all directions. This would mean that,
if the cosmos did have central point, such as a location with
coordinates (0,0,0), the bulk of the cosmos would be infinitely far
away from it. Thus if matter were to store its absolute
position it would need to store infinite values. This will
not be possible. The same issue will not be a problem for
velocity because a particle can never gain an infinite
velocity. This is because particles can only receive finite
forces, which lead to finite accelerations and hence finite velocities.
The second reason why matter does not need to store position is that no
physical interaction laws are based on it. That is, no
calculation of force is based on the distance between two objects.
This claim might sound remarkable because distance features prominently
in many force equations. For example both the electrical
force law (Coulomb’s) and the gravitational force law (Newton’s)
contain a distance-squared term in the denominator. Thus it
would seem the force between charged or massive objects is directly
dependent on the distance between them. Surprisingly however,
this is not the case.
To demonstrate this, consider two like-charged particles such as
electrons. We will call one the ‘source’ and the other the
‘target’. The force the target feels is calculated by
multiplying the magnitude of both charges and dividing by the square of
the distance between them. This would appear to make the
force a function of distance. In reality though, the target
doesn’t know anything about the source. The only thing it
feels is the field coming from it. That field could have
instead come from multiple charges located at a variety of
distances. Coulomb’s law is simply a way of determining how
the field strength of a point charge weakens as it expands uniformly
across a spherical surface in three dimensions. The same
argument can be made in regards to gravitational forces. That
is, a target mass responds to a local gravity-field strength rather
than to a distance from a source mass.
The principle of Cause &
Effect requires that the universe must contain all the information at a
given instant of time that would allow its situation to be determined
at a later point in time. It necessarily follows from this
that velocity must be stored within matter, as a property of
matter. It also follows that this velocity be an absolute
rather than a relative quantity and that it be stored as three
components corresponding to each of the dimensions. There is
possibly no way of detecting or measuring this absolute velocity since
all physical reactions (forces) are based on differences between such
velocities. The same conclusions cannot be said about
distances, or rather, positions. That is, position is not
stored within matter and the concept of absolute positions likely has