A/N: Okay, so I know it's been forever since I updated this (June last year if I recall correctly). Just to let you know, I have not abandoned this story and I plan to update this and my other stories more frequently.

Doctor Who and Stargate: SG1 are property of their respective owners. This fanfiction was originally written in French by
Duam78 and I have merely translated and added a few things with my creative license.

Enjoy!

Chapter 4: Explanations

"If I were you," said O'Neill. "I would move your little time machine."

"Why?" asked the Doctor.

"The activation of the Gate causes the formation of a vortex that extends beyond the event horizon, destroying everything in its path," Daniel explained simply.

"Oh, I see ..." There was a pause, then:

The Doctor rushed to the departure room, went into the TARDIS and in a few moments, he had it parked a few meters from the blast doors and well away from the Stargate. He then rejoined Sam, Daniel, Jack, Teal'c and Rose. The Doctor looked out towards the great ring, he turned to Carter.

"What is it really?" he asked.

"The Stargate?" she replied. "It's a device designed to manipulate space-time, mainly in order to create a vortex that allows us to travel quickly between two points in space. That teleportation is possible by decomposing the material constituting the traveler at the subatomic level and sending the material through the vortex created."

"Brilliant! And how did you come into possession of the 'Stargate'?"

"The Gate was discovered in 1928 by an Egyptologist in Giza, Professor Langford. He thought it was a kind of mythical door beyond, due to rough translations of ancient Egyptian designating it as "Heaven's Gate" or "Door of Paradise." In 1945, Professor Langford's daughter, Catherine, and her fiancé Dr. Ernest Littlefield, tried to operate the door manually manipulating the door and trying random addresses. They managed to open the door to an unknown destination. Ernest volunteered to go, and wearing a suit, he went through the Gate. But there was a problem with the energy supply to the Gate, and the connection went dead. It was impossible to recover Dr. Littlefield and so, following this failure, the military dropped the project and shut the Gate in a sealed container in the corner of a warehouse. Research resumed in the early 90s, under the leadership of Catherine. Thanks to Daniel Jackson, another combination was discovered, and the military managed to recreate a virtual DHD."

"DHD?" Rose queried.

"'Dial-Home-Device'," Carter explained. "Sort of like a phone dial that allows us to call another Gate."

"You said a 'virtual' DHD?" asked the Doctor.

"Yes," said Carter. "We don't have the original DHD. Normally, there would be one on each side of the Stargate. But as we don't have one, we managed to recreate a virtual one through a computer program that acts as a 'remote'."

"And how do you 'call' you these other worlds?"

"Just enter the correct coordinates. Seven symbols are selected from the address of the destination, and they validate the vortex shape. Neutrinos are transmuted into energy that can create such a vortex."

"Why seven symbols?" asked Rose.

"To locate a point in three-dimensional space, it takes six points (like the six sides of a cube)," said the Doctor knowledgeably. "And to determine the path to get there, we need a seventh point: the origin."

"Exactly, Doctor!" Carter exclaimed.

"The TARDIS behaves in much the same way," the Doctor said to Rose. "Except that it automatically calculates the coordinates according to the planet to which we want to go." He turned to the Captain. "How did you get access to these details?"

"I have been to Abbydos," Daniel explained. "They were engraved into a wall in a room that I discovered when I lived there."

"You're an alien too?" Rose asked, surprised. "You don't really look 'Spock'!"

"No, on my first trip through the wormhole, I decided to stay on this planet with my wife. I stayed there for about a year before Jack came back for me and I lost her," he explained sadly.

"You lost your wife?" Rose asked.

"It's a long story."

The Doctor, sensing that this was an uncomfortable topic for Daniel, continued his barrage of questions. "How does it work?"

"Stargates are made naquadah," Carter answered. "It's an extremely resistant metal and superconductor so the Gates are virtually indestructible. Distorting space-time requires considerable energy, so to open a vortex, the Stargate first accumulates energy in its naquadah battery. But the ambient energy is not sufficient to charge the battery in a reasonable time and the door must be powerfully energized before it can open a stable wormhole. As we have no DHD, we feed it with our own electricity. Once the wormhole is established, the door must always be fed in order to maintain the connection. In all cases, when the wormhole has been open for 38 minutes, consumption becomes such that it is impossible to keep the Gate open."

"So you just walk through to get to another planet?" said Rose. "That's practical!"

"It is a bit more complicated than that," said Carter. "When an object or person goes through the Gate they undergo a 'molecular disintegration'. In other words, each molecule is converted into energy by the Gate, to make the transfer possible. This 'copy', called 'energy pattern', is sent to the arrival Gate that will take care of converting the molecules back to their original form, and thus recreate the object or person on the other side. Physical bodies may only travel in one direction, under penalty of disintegration! To return, it is necessary to close the Gate and redial the home address. Only electromagnetic waves like radio waves can travel in both directions, this allows us to interact from several light years away.

"I'm beginning to understand what happened ..." said the Doctor thoughtfully.

"Someone other than me not understand these explanations?" asked O'Neill feeling left out.

"I…" Rose began. "I don't know…"

"I figured it out," said Daniel.

"As have I," uttered Teal'c.

"Ok, well maybe I'll understand by the third explanation," O'Neill sighed. "Time for dinner!"

A/N: Who feels like O'Neill right now? Does your brain hurt yet? R&R!