This is the big one, the premise that determines so much of the rest of Traveller. To be explicit:
2) There are no ansibles, subspace radio, or any other way for energy to travel faster than light speed. Sending a message means sticking it in a starship and jumping.
Don't the Ancients show that ansibles are possible within the universe but humans and most other species have not reached the TL for them?
I guess that is a bit of a semantic argument because any game at that kind of TL is not going to be Traveller as we know it.
MWM has many times said there is no ansible or any other type of FTL communication in the OTU.
The Author of the MgT Secret of the Ancients slipped in an Ancients ansible and got away with it. So now yet another difference exists between game universes.
I think the FTL limited has been retconned to 'no signals faster than a ship could jump' to let the Empress Wave slip by on a technicality, even if I suspect it was originally just an accidental conflation of parsecs and light-years that an editor might have caught...
I personally think the idea of the Ultra-High-TL ansible is a good idea for the sake of a believable TL progression (just well beyond TL15). It also has the advantage of ensuring that the "look-and-feel" of an Ultra-Tech society
does look much different from the OTU universe that we are familiar with, and not just the "same old thing" with a few more gadgets (just like a 21st Century Military/Navy & Society looks very different from a 13th Century Military/Navy & Society). But then this is a thing for relic technology and/or stories of precursor civilizations (or for brief one-off interactions with a distant but still extant Ultra-TL race who hopefully does not want to be overly bothered with "ants" like you as long as you do not bother them).
But having said that, "ansible" can mean different things.
It can mean:
- Near instantaneous communication system over interstellar distances with no appreciable lag-time (i.e. we can speak "face-to-face");
- Interstellar FTL Communication with a manageable lag-time (i.e. minutes/hours/days - like current in-system communications);
- Interstellar FTL Communication with a long lag time (i.e. weeks/months - but still better than lightspeed).
Each of the above could further be coupled with other limitations that impinge on its usefulness as well.
For example, in Larry Niven's Known Space Universe, FTL-Communication is accomplished by hyperwave, but hyperwave will not cross a hyperspace-singularity (and from the perspective of hyperspace, an entire star-system gravity-well typically appears as such a singularity). Thus, it is necessary to send a transmission via EM-Radio signal to a hyperwave relay station at the edge of a star-system which will encode it and then retransmit it via hyperwave to be picked up by a similar station at the edge of another star system until it reaches a station in the destination system that can transmit the signal via EM-Radio to an in-system receiver. (Alternately, a starship can also carry a hyperwave transceiver and send and pick-up signals directly as long as they are outside a hyperspace singularity). The speed of hyperwave itself in the Known Space Universe is for all practical purposes instantaneous relative to the astrographic size of Known Space.
In an IMTU
Traveller setting, one could modify this idea somewhat for use as well without necessarily breaking the core presuppositions of the setting as long as one is careful to consider the ramifications. As an example, let's suppose one wanted to build a "HyperComm Radio" using some type of "Jump-tech" principles for their IMTU setting. Let's give it the following properties:
- The wave-packets of the HyperComm signal are much longer wavelength than the "signal" of something the size of a vessel, and therefore much more susceptible to distortion, so they require a much more undistorted spacetime for transmission (i.e. they can only be cleanly transmitted beyond 100,000 diameters from a gravity well without significant signal distortion and degradation);
- Unlike a large mass (like a vessel) going thru Jump space with a highly defined position vector, a HyperComm signal is broadcast * (not narrow/beamcast), and will effectively propagate in all directions from its transmitter;
- The speed of the transmission could potentially be either:
- Maximum speed for the Order of the Hyperspace used (e.g. 6-or-9+ pc/week for Jump; 90+ pc/week for Hop; 900+ pc/week for Skip; etc.); or
- Encoded in the same way that regular jumps are encoded (i.e. J-1, J-2, J-3, etc.) based on current TL.
- The HyperComm transmission would arrive "everywhere" within the transmission range at the end of the 1-week (±10% [or ±30% (?)] ) transmission time.
* (EDIT: Another possibility is that the transmission could be narrowcast, but the shape/width of the "transmission cone" is based on the "Jump-rating" of the HyperComm transmitter - i.e. you need to build a transmission cone by counting out a number of hexes no greater than the "Jump-rating" of the HyperComm system.
The advantage to this would be that a ship could put out a "distress call" if it mis-jumped into an empty hex or were otherwise disabled (if the GM decided that the HyperComm transmitter was small enough to be carried by a vessel), or could send a message back to a home base with a lag time comparable to Courrier transmission rates, and still potentially have to encode it to be successively retransmitted to get to a final destination.
The disadvantage would be that anyone within range and the ability to crack encoding could potentially intercept transmissions, including a dedicated ship hovering in a Kuiper Belt or outside an Oort cloud at several light-days or light weeks distance (or even in an empty interstellar hex) monitoring and downloading communications traffic. So if you want to make sure your communications are delivered securely (as well as any small high-priority parcels), you still might have need of a Courrier or Packet Ship (or X-Boat) system.