Question on the Stargate Itself

[Metarock Sam]

The way i see it its basically like a phone system now on most landline phones you dont really know who is calling you untill you awnser and hear the message through this is like the gate system.

[_Owen_]

Except the Stargates create artificial wormholes, your telephone dosn't.

Owen Macri

[The Maneuver]

Except the Stargates create artificial wormholes, your telephone dosn't.

Owen Macri

It's still better than no analogy at all.
Find a real world analogy that can create artificial wormholes and people'll use it.
It is possible the Ancients came up with a way of reading incoming wormholes, but we've seen no evidence of it.

[_Owen_]

That is possible, it would be easy they just need something to trace the wormhole backwards and they would have the point of origin. We could do it send a radio signal backwards through the gate (something identifiable, then scan the galaxy for it. This would be incredible difficult and require incredibly advanced sensors, but it is possible, there are also several other ways to do it.

Owen Macri

[John Preston]

The gate itself knows, but as is proven by the fact that they are capable of going to planets where there is a lack of a DHD, the DHD itself isn't needed for "incoming" wormholes, and it is only an assistance for "outgoing" wormholes, on top of handling feedback issues from the stargate itself.

'Why does the Earth gate spin?'
- Because they use a computer, not a DHD nor the Gate's "backup" handling of incoming wormholes. Their computer most likely causes issues with the Stargate, causing it to need to "spin". However, it doesn't always spin.
Why?
Three theories
1) Sometimes the stargate/computers work fine.
2) Sometimes the gate is mid-dial.
3) Speed dial. The stargate on Earth can't be speeddialed, although Carter has been working on ways to shave off time in order to dial. However, other stargates can speeddial. This is most likely thanks to the presence of DHD's on their end.