It's been awhile since I've read any of E.C. Tubb's Dumarest of Terra series, and I only ever read a couple of them, but I remember that this was the premise of that series -- that Dumarest was always trying to find his way back to his lost home-world, which was Earth. I don't recall what (if any) rationale was given for why Earth's location was lost -- does anyone else who's read these books remember? (And btw, any Traveller fan should try to read at least one or two of these because there's a ton of Traveller in them -- they're low-end pulp as literature, but it's still fun to see where the inspirations came from, just like a D&D fan reading The Dying Earth or Three Hearts and Three Lions).

Quote from: Werekoala;356530If something happened that de-populated the Earth, either mostly or entirely, for an extended period, then it might slip out of the galactic mainstream.

Maybe something along the lines of a return of "Nemesis" that lets loose hundreds of comets on the inner solar system that pummel the planet, or a passage through a dust cloud along the galactic plane that dims the sun sufficiently to start an ice age and kills off most life on the planet.  It would have to be something dramatic enough that the technology of the time couldn't reverse it.

If Earth stops being an important world because of these (or other) factors, it might eventually become "lost". For an added bonus, instead of having it be centrally located in the empire, have it be off on a fringe or something. No reason why Earth would HAVE to be the center of things over the lifespan of a galactic Empire.

That's pretty much exactly what I was thinking: An interstellar-level disaster wipes out all human life on earth and makes the place uninhabitable for about 10000 years. Meanwhile, the colonies that were furthest from Earth are the ones that survive the most unscathed, and eventually, around one of these colonies, quite a distance further coreward than the Earth, there springs a new Galactic Empire of Humanity. Even more time passes, until eventually its known that the original homeworld was located somewhere in the spiral arm, but the exact location is not certain anymore, and the Galactic Empire is only now getting to the point where its beginning to explore those regions again, making new contact with some of the colonies in that area that survived (and usually ended up much worse off than the core-ward colonies did, some slipped into barbarism, lower tech, petty empires, weird cultures bred in isolation, etc). One of the goals now of interest for this new Human Empire is to find the missing homeworld, mainly for propaganda reasons.

RPGPundit

Quote from: JongWK;356536You'd probably need a massive effort to wipe out stored data and people who know about the Earth's location. In short, you need a galaxy-wide Crusade, Inquisition, computer virus, and/or plague. Dark Ages all over again, where this particular bit of knowledge is lost or jealously protected by some.

That begs the following question: What do you find once you reach Earth?

Ah, that's something for later on in the campaign.

RPGPundit

Personally, I don't think it's important to determine a credible reason why Earth is lost. I like the idea of the concept being shrouded in myth or legend.

Regards,
David R

One possibility could be that in an earlier dynasty of this new Human Empire, following the dark age that came with the collapse of the earth-based human empire, the new Colony-based imperial government had set itself up on a specifically anti-earth kind of ideological stance, ie. "the future is here now, on New Terra, the old Empire failed you, but this new Empire will flourish with a new beginning to create a truly Great and Bountiful Human Empire!", and that for political reasons it became anathema for several centuries to dwell on the question of "old earth", particularly if some of the earlier opposition to the Second Human Empire was focused on the myth of how great the old earth was and how these guys are just pretenders or something.
If it was politically dangerous for a few thousand years, that could explain how intentional imperial repression led to the loss of this data.  Now, tens of thousands of years later, a new dynasty finds itself in a situation that is totally reversed, and they are the ones who are making political use of the old homeworld, and suddenly want to try to find it again.

RPGPundit

You know, if you are looking for a disaster that may result in Earth being lost, a Near-Earth Supernova could do the job.

Does Earth have to be in the same location that it is currently in ? If you have a myth of a displaced Earth, you could have an Earth Empire which is so strange, near alien, to the New Colonists once it's eventually found.

Regards,
David R

Quote from: jeff37923;356747You know, if you are looking for a disaster that may result in Earth being lost, a Near-Earth Supernova could do the job.

That was actually number one on my list of disasters, because it wouldn't just have fucked up earth, but also pretty much all of the older colonies that were the original "core" of the First Empire.

RPGPundit

Quote from: RPGPundit;356755That was actually number one on my list of disasters, because it wouldn't just have fucked up earth, but also pretty much all of the older colonies that were the original "core" of the First Empire.

RPGPundit

That's the #1 candidate for the loss of the Solar System in StarCluster. We never specified it, though. Thought it was more interesting left unstated. Only ships beyond 60 ly when the incident happened survived.

-clash

At least one game of mine deals with the idea that empires rise and collapse and that because of that cycle it is very likely that Earth becomes lost to the current cycle's Empire.

Although the current era might find it again. You can't assume that tracking becomes absolute. After all, even with all our "vast" technology to stone ages, and GPS tracking. We still get lost. Still lose our car keys. Etc.

Humans will likely remain fallible, and that being the case well losing ONE planet might not be that hard.

Quote from: RPGPundit;356523How credible would it be, for a sci-fi setting, that an empire of our own descendants might have (possibly after some disaster) "lost" the Earth in the sense of not knowing where it is anymore; ie. 100 000 years after man first walked on the moon, humanity spans a vast galactic empire, and the actual location of the homeworld is uncertain?

Would there be features of galactic cosmography that would help make that more likely? Less likely? How hard would it be to find again?

RPGPundit

That's basically the premise of my old timey (since about 1978) homemade setting for Traveller, or any sci-fi I run these days.  

I was inspired by Larry Niven and a few metions of the Man-Kzin wars.  In that universe humanity was slowly but surely getting its but kicked from system to system by the Kzin.  You could imagine the Kzin made a point of seeking out other space faring cultures and enslaving them.  When Earht saw through it's telescopes second (IIRC) Kzin fleet heading to conquer Earth (this is all STL) what would people do?

IMTU a similar encounter occured.  The only rational thing to do was run, massive sleeper ships were made. It was an exodus.  No records were kept or made of where the exodus ships were going in the hopes the Kzin couldn't follow.  No details on the location of earth was included on the ships, folks were not coming back and it was feared other aliens existed just as dangerous as the "Kzin" out there.  So the colonies don't know where Earth is, it's often a state secret even what general direction it may be.  Of course no one knows what ended up happening to old Earth.

SO they didn't so much as lose Earth but intentionally wiped this navigational data and supress all other knowledge of where it may be, lest it fall into the wrong hands.  The myth of Earth is also more politically maleable than a reality that refuses to cooperate.

BAH I SAY!!

Advances in technology will be met at every step with advances in bureacracy!  We can lose a planet any time we like!

Before settling on how Earth was lost, you might want to consider why your PCs are looking for it.

Let's say you've got two campaign ideas-

One is a mad cap pan-galactic scavenger hunt for the E.S.S. Exodus' Navi Com and the fabled wherabouts of Old Earth contained within.

The other features a fleet of political refugees and romantics out to re-settle the Terran homelands against the wishes of the degenerate and corrupt Void Principate.

Personally, I think each scenario is suited to a different explaination as to why Earth has been lost. In someways it might be easier to work back from your campaign's premises.

And if Earth having been lost is just a bit of background fluff for your game, then I think you can safely gloss it over with 'shrouded by the mists of time' and 'subject to thousands of myths and rumours.'

Quote from: David Johansen;356799BAH I SAY!!

Advances in technology will be met at every step with advances in bureacracy!  We can lose a planet any time we like!

So very very true.

Quote from: David R;356748Does Earth have to be in the same location that it is currently in ? If you have a myth of a displaced Earth, you could have an Earth Empire which is so strange, near alien, to the New Colonists once it's eventually found.

Regards,
David R

Spot on!  Earth could have moved.  Hell the population could have found a technology that turned the entire planet into an interstellar craft.  Then got lost.