The Imperium of Mankind is spread across almost the entire galaxy and consists of more than a million worlds. Although this is a huge number of planets it is as nothing when compared to the immense size of the gallaxy. The Imperium is actually spread very thinly across space: its worlds are dotted through the void and divided by hundreds, if not thousands of light years. It is therefore wrong to think of the Imperium in terms of a territory which extends across the gallaxy. The truth is far more complex. Within the galaxy are countless alien civilisations, many Ork empires, and vast areas occupied by the Tyranids or given over to Chaos. Most of the galaxy remains unexplored. Who knows what secrets lie undiscovered amongst the stars? Undoubtedly there are other advanced civilisations, lost human colonies, and the ruins of long dead races waiting to be explored.

The pattern of human settlement throughout the gallaxy undoubtedly owes much to the nature of space travel. All interstellar travel is undertaken using power warp drives which lanuch a spacecraft into the alternative dimension of warp space. Within warp space a ship can cover the equivalent of many thousands of light years within a relatively short time, dropping back into real space far away from its starting point. Because of the unpredictable and turbulent nature of warp space, some parts of the galaxy are harder to reach than others. Some zones are eternally isolated by violent currents of movement within warp space. Other areas are difficult to get to or can only be reached during periodic lulls inthe warp. More bizarre still, some part of warp space act like power vortices, pulling or sucking helpless spacecraft to their doom. Only the spaccraft of the Imperium can fully exploit the medium of warp space to travel from one side of the galaxy to another. Other races, such as Orks, can only travel short distances through the warp and this limits the size of thier individual empires and prevents them becoming united. It is only this factor which enables the Imperium to function as a whole.

THE TIDES OF THE WARP                                                                                                         The reason why spacecraft of the Imperium can move quickly over the entire galaxy, while other races suffer more restrited ans slower spaceflight, is a combination of three factors. The first is the maintenance of the ancient technology by the Adeptus Mechanicus - the Tech Priests of Mars who preserve the lore of ancient science on the behalf of the Adeptus Terra. Without the technological advantage of efficient warp engines it would be impossible for the Imperium to defend its scattered planets. The second factor is the existence of human mutants known as Navigators - a race apart which traces its origins to uncertain times of the Dark Age of Technology. Only a Navigator can pilot a ship within warp space. His swollen cranium house a mind which is to the tides and currents of the warp, enabling him to guide his ship through warp space to its eventual destination. Otherraces must rely upon guesswork and endless corrective manoeuvres to travel even short distances through the warp.

The third factor which makes warp travel possible is the immeasurably powerful psychic beacon called the Astronomican. Broadcast by a choir of psykers from Earth, the Astronomican reaches out through warp space, guilding spacecraft to their destination. Only a Navigator can sense the guiding light of the Astronomican, and only he can follow its psychic signal. It is the Astronomican which allows a Navigator touse his powers to the full; without it not even the most powerful Navigator could pilot his ship over the immense distances which separte the worlds of the Imperium.

PERILS OF THE WARP                                                                                                                Warp space is a alternate dimension composed of energy as opposed to physical space of the marerial universe. There are dangers within the warp which can wreck spacecraft and carry them off course, unexpected turbulence, warp storms, and loops that can trap a ship for eternity. These dangers, though considerable, are nothing compared to the greater and unimaginable dangers that lurk in warp space.

To understand these dangers it is important to realise two important facts about the nature of the warp. Firstly, warp space is composed entirely of psychic energy. It is this psychic energy which a human psyker draws upon to use his powers, to send telepathic messages hurtling through the warp from world to world, or to propel a psychic bolt of energy against a foe.

Secondly, warp space is not empty but inhabited by many strange and dangerous creatures, the most dangerous of which are the Great Gods of Chaos and their legions of daemons.

Daemons lust after the flesh and blood of living creatures. They want only to destory mankind, to drag the souls of men back to their shadowy realm, to obliterate the material universe and engulf it within the energy of warp space. Fortunately this is not easy to accomplish. Daemons cannot exist for long in the material universe and they need to find psychic gateways in order to leave the warp. Such gateways exist but they are rare. The most vulnerable gateways of all are the mind of psykers. A psyker's power open up a path between reality and the warp, a path which a daemon may find and follow to the mind of the psyker himself.

Such are the dangers of the warp - at once a boon and protector, and an unimaginable horror. Without the ability to travel throughout warp space the Imperium would certainly collapse and mankind would fall victim to the thousand perils that threaten to destory it. Without psykers the whole system of astro-telecommunication would be non-existent, and it would be impossible to guide the Imperium's armies and fleets against its many enemies. For these reasons at least warp space is essential to the Imperium's very existence. Yet at the same time warp space harbours terrors so great, dangers so profound, that much of the Imperium's efforts are spent in combat against them.

Gameplay Notes: Human and alien ships may safely make Jumps of 1 parsec (Jump-1) without the aide of a Navigator.  Human ships with a Navigator may make Jumps out to 6 parsecs (Jump-6) relatively safely.  These are termed "safe jumps".  When a ship makes a safe jump it rolls 2d6.  If it rolls a double 6 a mishap has occurred.  Roll on the Mis-jump table on pg 353 of the T20 Handbook.   All human and alien ships may attempt to make longer jumps without the aide of a Navigator.  These ships roll 1 dice and on a 6 a mis-jump occurs.  Add +1 to the roll for every parsec over 1.  So if an Ork ship attempts to make a Jump-3 it adds +2 to the dice.

Eldar have access to the Webway which allows both man and material to move from planet, Craftworld or deep space.  But the Webway is limited, it only goes to certain places and not all exits can accommodate large vessels like ships.  Eldar tend not to move more then 1 parsec away from a Webway exit.

Otherwise Jumps work per standard Traveller rules.  For mis-jumps you can add some interesting twists like a Warp-Entity encounter.