As seen in "Year of Hell", the Timeship is a device which is capable of rewriting history. This is nothing new - we've seen episodes which involve some action that changes the future many times in Trek, right back to the TOS episode "The City On The Edge Of Forever". However, the Timeship works in a slightly different way - instead of going back into the past and effecting some change, the Timeship fires a beam of some kind of energy which removes the target completely from the timeline. The result is a "temporal shock wave" which spreads out through space, changing everything it passes over to the way they would have been if the Timeships target had never existed at all. Hence if you fired the Timeships main weapon at, say, Germany, then the world would literally vanish and be replaced by a world in which Germany had never existed.

On the face of it this is a pretty impressive technology, but it has its drawbacks. Namely, the universe is an insanely complex place and many of its various bits interact with one another in ways which are both subtle and gross. Most people have heard of the so-called "butterfly effect", which encapsulates the idea that a very small change such as the flap of a butterfly's wings can have a very large scale effect and unpredictable effect such as a hurricane half a world away. This is the basis of Annorax's problem - in order to restore his Empire, he must know exactly where to intervene in the timeline. This process can take months of calculations, and still doesn't work most of the time - indeed, in the episode the Timeship never once achieves the desired results with any of its incursions.

The Timeship itself is stated to operate "outside space time", and this apparently confers several advances. Annorax indicates that he and his people have all eternity to complete their task; the obvious implication is that they are not ageing, but this is improbable to put it mildly. Since Annorax and his crew are able to move around and breathe, time of some sort obviously does exist on the ship. Their bodies continue to operate, so chemical reactions are still working - surely they are indeed ageing. My guess would be that Annorax meant that he could take a long time to complete his task because once accomplished those restored would not have been aware that there had ever been a problem. As an aside, it's possible that the Krenim are normally immortal anyway, so justifying his "all eternity" phrasing.

Another advantage of this "outside time" effect is that the Timeship is invulnerable to conventional weaponry - Annorax specifically says so when Voyagers fleet attacks at the end of the second episode. The episode gets around this by having the ships 'temporal core' sabotaged to make it vulnerable.

When the Timeship first encounters Voyager, we are told that the ships mass limits it to warp 6 at most - this is, amazingly enough, the first canon statement to specifically establish that the mass of a ship is a factor in how fast it can go at warp speed!

Scaling the Timeship is a difficult problem. What I did was make a video capture of the scene where Voyager rams the Timeship and compare the width of the saucer section with the width of the circular feature which Voyager rams. After various estimates, I get the circular feature to be just about one half the width of Voyagers saucer section, which is 128 metres across. With the circular feature 64 metres wide the whole Timeship comes to 1,240 metres - about the size of a D'Deridex class Warbird.

One final and faintly amusing note. As British readers will know, the name "Annorax" is something of a play on words over here. There is a kind of coat called an "Anorak", and in the UK at least this coat has become heavily identified with what the US would know as a Nerd - to such an extent that the word Anorak is virtually interchangeable with Nerd. The word is often labelled at Trekkers over here, and I often wonder if the writers of this episode had this in mind when creating the character of Annorax!