Galactic barrier The galactic barrier was an energy field composed of negative energy surrounding the rim of the Milky Way Galaxy . Invisible to both the naked eye and visual recording equipment at a distance , at close range the barrier shines with a purple - to pink - colored glow . No form of transmission was known to be capable of penetrating the barrier . ( ) Warp travel through the barrier caused extreme sensory distortions . ( ) The barrier had been encountered on several occasions by Earth and Starfleet vessel s . ( ) History . The first encounter involving an Earth vessel occurred in 2065 with the . The ship was swept into the barrier by a magnetic storm . Subsequent events resulted in the destruction of the " Valiant " and the loss of all hands , leaving the barrier ' s formal discovery to wait two hundred more year s . In 2265 , the under the command of Captain Kirk discovered the disaster recorder ejected from the " Valiant " . Decoding its message , they retraced the " Valiant " s path , being almost destroyed in the process . At that time the barrier did not register at all on the " Enterprise " s sensor s , although the ship ' s deflector s did react to it . Entering the barrier is extremely hazardous . Shields could not block all the energies of the barrier ; the leakage was sufficient to heat up the hull to over 2 , 000 degrees , ( ) damage several systems and disable the warp drive of the " Enterprise " . Also passing the shields and hull were strange electric shocks to the nervous system s of the Human crew members with high esper rating s . In most cases this caused death from brain damage , as was the case for nine " Enterprise " crewmembers . Individuals with the highest ESP ratings such as Dr . Elizabeth Dehner ' s 089 and Lieutenant Commander Gary Mitchell ' s 091 survived the shock and were altered as a result . They developed a multitude of psionic powers at a geometric rate . They began to view their former friends and shipmates as lower lifeform s . This transformation was known to have happened at least three times , with the best known example being Mitchell . ( ) In 2268 , Kelvan s from the Andromeda Galaxy entered the Milky Way Galaxy through the barrier . Their advanced multigenerational ships were damaged by the barrier and subsequently destroyed . The Kelvan survivors of one ship required a new vessel for the journey home . They hijacked the USS " Enterprise " and refitted it to survive the barrier and the intergalactic journey . Presumably , due to improvements in sensor technology , this time the " Enterprise " s sensors registered the barrier as negative energy , but of such magnitude that all instruments were off the dials . The option to flood the " Enterprise " s warp nacelle s with positive energy through control valves was available to Kirk , but not taken , during the passage through the barrier . Combination of that positive energy and the negative energy of the barrier would have destroyed the ship . ( ) Later that year , the " Enterprise " left the Milky Way Galaxy when Larry Marvick , driven mad by the sight of Medusan Ambassador Kollos , sought to escape his tormenting visions . During that excursion the ship was stranded inside a space - time continuum void deep within the barrier . No sensor data or reference points were available to exit the void in the right direction . Fortunately , Kollos was able to help pilot the ship out . ( ) Appendices . Background information . The script of " Where No Man Has Gone Before " likens the galactic barrier to the aurora borealis . The composition of the barrier was somewhat controversial , based on the analyses during both encounters , as it was initially totally unknown . Negative ( as in having no detectable ) energy , radiation and density , but later on in it is directly and clearly stated to be in fact negative energy ; not just negative ( in ) energy . This is evident from the plan to destroy the ship by venting positive energy inside the barrier to cause an explosion . In " " , on page 11 , the barrier is depicted as a toroidal shape that surrounds the entire galactic disc . It ' s not situated at the rim as directly stated on screen in , but only thickest at the rim ; over 10 , 000 light years thick , starting out from a distance of 40 , 000 light years from the center of the galaxy , outward . Closer to the UFP ' s neighborhood of the galaxy , the barrier thins down to a thousand or so light years above and below . Even a large number of visible stars in the outer parts of the galactic disc are situated inside the barrier in the " Star Trek : Star Charts " cross - sectional view of the galaxy . Furthermore , the " Valiant " , the " Enterprise " , the Kelvans etc . didn ' t exit , enter or try to exit the galaxy throughout the rim , but from the closer and thinner above and below parts of the barrier . Visual evidence presented in the episodes would however contradict this notion . " Star Trek : Star Charts " also states that the neurogenic effects of the barrier are unpredictable . The energy field of the barrier joins up with the Great Barrier at the center of the galaxy . It is stated to be a distinct but related energy field . " Star Trek : Star Charts " would however seem to contradict itself on page 13 , as the is stated to have started its journey home from a distance of approximately 50 , 000 light years from the galactic center . This would have placed it well within the barrier based on the earlier depiction on page 11 . Apocrypha . Greg Cox ' s " " novels state that the galactic barrier was in fact created by the Q Continuum as a method of preventing the powerful being known only as " 0 " from returning to the Milky Way Galaxy , from which he was banished for his destruction of the Tkon Empire . These novels also explain that the telepathic powers that occur as a side effect of exposure to the barrier in telepaths are caused by the power of the Q that exist in the barrier , while those who develop a god complex are ' infected ' by the presence of 0 , who constantly attempts to affect beings on the other side to give himself access to the galaxy once again . During an attack by the Calamarain , the was forced to hide in the barrier , but Lieutenant Reginald Barclay managed to come up with the idea of using the bio - neural gel pack s to absorb the psychic energy from the barrier to enhance their shields , providing some improved protection from the barrier ' s psychic influence . As the " Enterprise " departed the barrier , Betazoid scientist Lem Faal managed to briefly open an artificial wormhole leading to the other side . However , as this resulted in 0 briefly returning to our galaxy and only being defeated by the alliance of Q and the Calamarain , it is unlikely that the Federation will ever use this technology to begin exploration in other galaxies . In " Q - Squared " , a disembodied Q is the one who takes over Dr . Elizabeth Dehner and Lieutenant Commander Gary Mitchell . In the " " series of books , a member of the Nuyyad race is killed after becoming god - like in power from exposure to the barrier . However , he remains an energy lifeform and returns to the barrier . According to the game " " , the library computer entry on the planet killer mentions a school of thought which believes that the galactic energy barrier may have been created by some ancient race as a safeguard in order to keep things such as the planet killers out of the galaxy . The entry also states that if this is true , then the barrier is not very effective .