The Praxis Mystery

Written: 1999.02.28
Last Revised: 1999.03.23

Praxis explosion shockwave

In the year 2293, the Klingon moon Praxis, described by Captain Sulu as "their key energy production facility," exploded in a violent cataclysm that had numerous far-reaching consequences. Chief among those consequences were:

  1. The Klingon homeworld Qo'noS lost most of its ozone layer as a result of the blast. This indicates that the Klingon moon's explosion caused significant disruption in the atmosphere of Qo'noS.

  2. A Federation starship on the other side of the Neutral Zone was buffeted by a "subspace shock wave", apparently within minutes. This indicates that the subspace shock wave travelled at superluminal speed.

This incident has been used by numerous Federation cultists as evidence of advanced Klingon technology, since they have a tendency to accept any optimistic ramifications and ignore the obvious contradictions. The following is a paraphrased amalgam of the numerous Federation cultist claims regarding this incident:

"An incredible amount of energy must have been required to create a blast wave that would affect ships light years away. This indicates the awesome state of Klingon power generation technology."

This claim, phrased in countless different ways, has been repeated by Federation cultist after Federation cultist for years. However, this conclusion ignores numerous obvious contradictions, either deliberately or as a result of scientific ignorance:

  1. How could a shockwave move at superluminal speed? Even an infinite amount of energy will not accelerate a single proton beyond the speed of light, never mind the mass of a small moon. Even if the matter were entirely converted to massless energy (eg. photons), it would only travel at c.

  2. What was contained in the shockwave? A shockwave is a pressure wave that moves through matter. In the vacuum of space, a shockwave can only be a moving front of matter. But where would all of this matter come from, to produce a shockwave that is still visibly dense after dispersing over a distance of many light years? The mass of the Praxis moon would be insignificant at this distance.

  3. How could this blast have such an inconsequential effect on the nearby planet Qo'noS? The shockwave was so powerful that it could affect a starship which was, in all probability, several light years away. Why didn't the blast destroy Qo'noS?

  4. Why did we see the shockwave moving toward us? It was moving at superluminal speed, so we should not have seen anything until the moment the shockwave reached us, because it would quite literally be out-racing its own image.

  5. Why was the shockwave a planar ring? The shockwave, as seen in ST6, was clearly a planar ring. Furthermore, it appeared to be only one or two kilometres thick even when it struck the USS Excelsior, light years away.

This incident cannot be explained with 20th century physics. However, if we resort to "treknobabble", we can easily solve this riddle. The treknobabble in question is based on the "subspace mass-lightening" technology employed by the Federation.


What is subspace? According to the TM, subspace is another "strata" of the space-time continuum. We can derive several conclusions about the often-abused Federation term known as "subspace", based on canon observations:

  1. Energy, and by extension, mass, can interact with objects in realspace even when it is in subspace. We know this because a long-range subspace sensor ping would be utterly useless if it did not reflect off an object in realspace.

  2. Subspace is probably collinear with realspace, ie- all points in subspace are coincident with points in realspace. We know this because subspace sensors can determine both distance and direction information.

  3. The interaction of subspace mass/energy with objects in realspace must be a weak interaction. We know this because objects in subspace can move through objects in realspace with only moderate damage, such as the Rutian terrorists who suffered only mild cellular damage from subspace transport through solid rock.

  4. Subspace mass/energy can apparently travel at virtually any desired speed. We know this because subspace fields are employed in both impulse and warp drive propulsion systems, and also because sufficiently high-powered subspace communication relays can increase both the range and speed of subspace communications, as demonstrated by the Hirogen relay network seen in Voyager.

  5. Mass, and by extension, energy, can exist "partially" in subspace. In other words, subspace is not an "exclusive OR" proposition, where something can exist in subspace or realspace but not both. We know this because most of the mass of a starship is "submerged" in subspace when it activates its so-called "mass-lightening field", but the ship does not completely disappear into subspace.

  6. Subspace is probably much like empty interstellar space, in that it probably contains very little matter or energy. We know this because mass/energy in subspace appears to move with no detectable resistance, and because no starship has ever been seen to encounter natural objects (such as planets or stars) in subspace. Since we know that subspace mass/energy can interact, however weakly, with realspace objects, a detection or worse yet, a catastrophic collision would have inevitably happened by now if objects were plentiful in subspace.

  7. Objects in subspace will not naturally stay there of their own accord (this may explain the previous phenomenon). A natural attraction draws mass/energy from subspace into realspace. We know this because subspace mass/energy invariably returns to realspace unless it is actively kept in subspace by some technological means. For unknown reasons, some objects take longer to return to realspace than others. For instance, Beverly Crusher's warp-bubble prison took many hours to collapse, while the mass/energy that was "submerged" into subspace with a "static warp shell" apparently returned within seconds of field shutdown in "Deja Q".

  8. Subspace responds very strongly to mental manipulation. We know this because the Traveller essentially stated it to be true and demonstrated his control over this phenomenon by propelling the Enterprise-D to fantastic velocities. Furthermore, we know that this ability is not intrinsic to the Traveller or his race, because an ordinary human such as Beverly Crusher was able to mentally define the reality of her surroundings when trapped in a subspace "warp bubble".

  9. There appears to be little or no inertial resistance to acceleration in subspace. We know this because starships apparently do not have to expend any energy to accelerate the portion of their mass that is "submerged" into subspace. If there was significant inertial resistance to acceleration, a starship would gain nothing from submerging its mass into subspace because it would still have to overcome inertial resistance to accelerate itself.

  10. Both Federation and Imperial communications systems employ "subspace" transmissions, according to the TM and the SWEGWT. Although it is possible that this is a mere coincidence of terminology, this suggests that they are based on the same technology. The limitations are similar: according to the aforementioned sources, both Imperial and Federation subspace transceivers have a range in the 1 to 100 light-year range (25 for a GCS, and 100 for an ISD).

Armed with the preceding facts about subspace, we can deduce several things about the nature of subspace:

  1. Contrary to some popular cross-universe comparison claims, subspace is not the same phenomenon as hyperspace. There are some superficial similarities, such as the ability to greatly exceed the speed of light and the collinearity with realspace, but subspace objects can be stationary or moving at superluminal speeds, while hyperspace objects always move at superluminal speeds. Furthermore, objects released into hyperspace stay there, while objects released into subspace eventually return to realspace of their own accord.

  2. It would be very difficult to use an object in subspace as a weapon (eg. a superluminal projectile weapon). Because subspace mass/energy interacts only weakly with realspace mass/energy, a subspace projectile would probably pass through a realspace target with minimal (perhaps even undetectable) damage. This explains why no one in the Federation has ever developed a subspace projectile.

  3. It would be inadvisable to ram an enemy starship with a starship, torpedo, or fighter that is partially "submerged" into subspace. This is because the violence of the collision would probably "shear off" the portion of the ship that is in subspace, and since subspace mass/energy interacts weakly with realspace mass/energy, the majority of the ship's mass would be ineffective as a ramming projectile. This explains why ramming attacks (seen in "A Call to Arms" and "Tears of the Prophets") are performed at very low sublight speeds of a few km/s or less, rather than the relativistic speeds known to be available. They cannot achieve those high sublight speeds without using their so-called "mass-lightening" technology, but this technology defeats the purpose of ramming by ensuring that most of the ship's mass is not in realspace. The same restriction would obviously apply to photon torpedoes.

  4. It would be inadvisable to develop a subspace transporter system, because the interaction between subspace mass/energy and realspace mass/energy, however weak, would still cause damage to cellular tissues. In "High Ground", the Rutian Ansata terrorists' dimensional transport system may have been a subspace device, in which case its behaviour would have been consistent with this prediction. Even if the Ansata dimensional transport system was not based on subspace, the behaviour of subspace sensors indicates that subspace energy must interact with realspace energy.

  5. A Federation starship must submerge almost all of its energy into subspace to achieve the speeds attributed to it. A GCS can accelerate at more than 10 km/s², but a mere 20GW will push it beyond the warp-speed barrier (ref. TM). Therefore, a GCS must be capable of accelerating at 10 km/s² with less than 20 GW of propulsive power. The power requirement for 10 km/s² acceleration is 50 MW per kg of starship mass, so if a GCS can accelerate at 10 km/s² with less than 20GW of propulsive power, its mass must be lower than 400 kg! Therefore, a 4.5 million ton GCS must submerge at least 99.99999% of its mass into subspace to achieve its rated acceleration.

Explaining the Praxis Mystery

Now that we have deduced some of the basic characteristics of subspace, we may be able to explain the Praxis mystery. The five basic issues will be addressed one at a time:

How can a shockwave move at superluminal speed?

The most obvious answer to this dilemma would be that most of the energy of the Praxis blast must have somehow been "pushed" into the mysterious realm of "subspace". Since Praxis was an energy production facility, it is possible that it was employing technology that would cause this to happen.
If the energy was mostly in subspace, then it would have obviously been able to move at superluminal speed, hence its quick propagation to the USS Excelsior's location on the other side of the Neutral Zone.

What was contained in the shockwave?

It could not have been matter. A moon (or even a planet or star) simply doesn't contain enough mass to produce a consequential shockwave many light years away. To provide a concrete example, suppose the Earth's moon is scattered through subspace so that its entire 7.35E22 kg mass is evenly hurled outwards to a distance of 3 light years in every direction. At the edge of this 6 light-year wide "sphere", there would only be a few trillionths of a kilogram of matter for every square metre of its surface.
If we imagine that this mass is entirely converted to EM radiation and hurled into subspace, we would still have an energy flux of well under 1 MJ per square metre at the surface of our hypothetical 6 light-year wide sphere. The USS Excelsior would receive less than 10 GJ of energy. This would explain why it wasn't damaged, since 10 GJ is nowhere near its shielding limits. This is far more realistic than assuming that the shockwave contained matter, but it is still difficult to reconcile with the fact that the Excelsior was knocked off course by the blast. 10 GJ of energy would have imparted less than 68 kg*m/s of momentum to the starship even assuming perfect 180 degre reflection, and this would have been totally inadequate to knock the ship off course.
This is superficially confusing, but we know that under high impulse power, most of the ship's mass was submerged into subspace. Furthermore, we know that the laws of physics are substantially different in subspace. Most importantly, we know that there is no inertial resistance to acceleration in subspace, so the concepts of inertia and momentum may be nonexistent there.
Therefore, we can theorize that the only resistance to acceleration would have been the portion of the Excelsior that was still in realspace. This portion would have acted as an anchor, to slow down the subspace-submerged portion of the ship that would otherwise have been "dragged" along with the energy wave at tremendous, possibly superluminal speed. Since we know that almost all of the mass of a Federation starship is in subspace during high-impulse operations, this theory provides a plausible explanation for the large recoil suffered by the USS Excelsior, in spite of the small momentum increase that should have resulted from the blast.
An interesting ramification of this theory is that the Excelsior might have been virtually unaffected by the blast if it had been coasting rather than running at high impulse.
Excelsior 1 The USS Excelsior just before the moment of impact. The shockwave is approaching, and fills the screen. Click on image to enlarge.
Excelsior 2 The USS Excelsior just after the moment of impact. It is attempting to "turn into the wave", to ride it out. Click on image to enlarge.
Excelsior 3 The USS Excelsior just after passing through the wave. Click on image to enlarge.

How could this blast have such an inconsequential effect on the nearby planet Qo'noS?

If the moon's mass/energy was submerged into subspace, then it would have passed through the planet Qo'noS with minimal interaction. The loss of the ozone layer would suggest that electromagnetic interactions between the blast wave and the planet's ozone molecules somehow resulted in the disruption of molecular bonds in those ozone molecules.
This is similar to the theory that the Excelsior might have been unaffected if it had been coasting rather than running at high impulse, and it may also explain why space stations in the Qo'noS area were not all destroyed. Since they are immobile, their mass would have been entirely in realspace (just like the mass of Qo'noS) and they would have suffered only mild damage from their weak interaction with the subspace mass/energy of the shockwave.
A logical ramification of this explanation would be that all of the denizens of the Klingon homeworld Qo'noS should have suffered mild cellular damage, since the blast wave would pass through the entire planet with the same weak interactions that caused it to disrupt the planet's ozone layer. There may have also been molecular-level damage throughout the entire planetary mass, as well as all of the structures on its surface. The Klingon High Command may have deliberately concealed this information from its populace, as well as outsiders like the Federation and the Romulan Empire, to keep the true extent of the disaster from becoming public knowledge.
This explains the fact that the explosion did not destroy Qo'noS, or even the entire Praxis moon itself, as seen in the following screenshot:
Praxis image after blast

Why did we see the shockwave moving toward us?

Since subspace exists beyond the perception of human beings in realspace, we should not be able to see a subspace shockwave regardless of its speed. We certainly should not be able to see a superluminal shockwave, since it would be literally out-racing its own image.
Therefore, the scene in the beginning of ST6 must have been depicted from the perception of a starship or space station near Qo'noS. This space station's viewscreens, like the viewscreens on starships, would create visible representations of objects that are not normally visible. This would explain why superluminal warp-driven ships can be seen approaching (which happens often in Star Trek) and also why the Praxis subspace shockwave could be seen approaching.

Why was the shockwave a planar ring?

The shockwave could not have been a planar ring. The probability of a planar ring just happening to be oriented so that it would strike the Excelsior, light years away, is so small that it can essentially be disregarded. The shockwave must have been a spherically expanding phenomenon.
However, if the visible shockwave in the opening sequence of ST6 was indeed a visible representation from the perspective of a nearby starship or space station, then the planar nature of the ring may be part of the visualization algorithms. Those algorithms may be designed to depict shockwave phenomena in such a manner that the crew can see the phenomena and react to it, without obscuring the crew's entire viewscreen.
If the shockwave were depicted in its full, spherical form, then nothing behind the wavefront woud be visible. One can easily envision reasons why the viewscreen would be designed to deliberately depict spherical shockwaves as planar rings, so that the crew recognizes their existence but can still see objects behind the wavefront.


The Praxis explosion is an excellent example of the strengths and weaknesses of Federation and Klingon subspace technology. Their heavy reliance on subspace technology allows them to greatly reduce their energy costs for performing functions such as high-sublight propulsion, but it also makes their ships extremely vulnerable to subspace disturbances. In some cases, Federation starships can be tossed about like leaves in the wind, while an inert asteroid would have been serenely unaffected.

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