How 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

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

Any species that is expanding through the galaxy would have to have a sophisticated enough - and redundant enough - navigational function that this would be ridiculously unlikely. I say function rather than program because how people store and retrieve information is likely to evolve drastically over 100,000 years. I doubt even a concerted effort to wipe its location out would succeed.

-clash

If 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.

Quote from: flyingmice;356527Any species that is expanding through the galaxy would have to have a sophisticated enough - and redundant enough - navigational function that this would be ridiculously unlikely. I say function rather than program because how people store and retrieve information is likely to evolve drastically over 100,000 years. I doubt even a concerted effort to wipe its location out would succeed.

This pre-supposes that technology expands (or at least fails to contract) indefinitely, and that all information is always stored forever. It also supposes that, in all the information acquired and maintained about everything ever for a hundred thousand years, there's a way to retrieve the one bit you want.

I think every single premise in there can be plausibly questioned, and any one could create the desired scenario.

You'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?

Perhaps if we were dealing with a Alien Jumpgate type system and the Earth's gate was somehow destroyed?

Quote from: Halfjack;356534This pre-supposes that technology expands (or at least fails to contract) indefinitely, and that all information is always stored forever. It also supposes that, in all the information acquired and maintained about everything ever for a hundred thousand years, there's a way to retrieve the one bit you want.

I think every single premise in there can be plausibly questioned, and any one could create the desired scenario.

No, it doesn't, Brad. It posits that technology fails to significantly contract everywhere at once, and to the point where basic navigational data is discarded or destroyed in all places. To get to this point means that after spreading through the galaxy, all human settlements, and all non-human settlements which have this data from humans or their own explorations, are simultaneously hammered back to a world-bound low-technology culture which cannot support data storage and retrieval for such important data as space navigation. I find this extremely unlikely. Otherwise it may be temporarily unavailable in certain areas at certain times, but it will infill from areas where it has been preserved once the area affected regains its space-faring culture.

-clash

Quote from: cnath.rm;356539Perhaps if we were dealing with a Alien Jumpgate type system and the Earth's gate was somehow destroyed?

That scenario was my first thought also, but even then you most probably know the astronomic location even if you won't be able to reach it.

I think if there was some event that led to loss of information. Perhaps they hadn't had any need to go back to the earth for some time (is it still inhabited?). In this scenario the event in question would have probably led to the loss of other locations.

I do think this is a tall order. It would be like the British Empire forgetting how to get back to England. But it is space you are dealing with, and the timescale is much larger, so it is more plausible I suppose.

Well if you had an orginzation like in Dune that controls all the navigation. They are somehow destroyed, broken up, or what not by a war, or what have you. Then other people would start trying to re-explore the navigation routes. Perhaps there are reminants of the guild floating around. But no one individual has the whole picture of the routes.

Could be a good start on the concept of the lost earth.

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

I think it would be highly unlikely that Earth could be "lost" like that.

I think it would be far more likely that Earth would become a fought over religious icon, like a planet-sized version of what Jerusalem is today.

Quote from: flyingmice;356527Any species that is expanding through the galaxy would have to have a sophisticated enough - and redundant enough - navigational function that this would be ridiculously unlikely. I say function rather than program because how people store and retrieve information is likely to evolve drastically over 100,000 years. I doubt even a concerted effort to wipe its location out would succeed.

Like Ur and Babylon? While knowledge of their existence persisted it wasn't until 19th century archeologists started digging that they were found again.  

Barring some catastrophe the a likely scenario is that planet will still be inhabited but the fact that it was Earth, the cradle of humanity would be lost.  

What it would take to do that is not any particular aspect of stellar cartography but a dark age where human knowledge is lost. Then later regained. If there are no dark ages then I agree with Clash that there is little chance that Earth's location would be lost.

Ur and Babylon's location were lost because of a multitude of changes that occurred in Mesopotamia leading the locations to be abandoned and then later forgotten.  It has not happened to Rome or most of the Greek cities yet. But it possible the location of some of the older Greek City-states that were abandoned (Sparta for example) could be lost if a dark age fell on our civilization.

Even if Earth was lost there the idea that the region was humanity's cradle would likely persist.

Quote from: Ronin;356579Well if you had an orginzation like in Dune that controls all the navigation. They are somehow destroyed, broken up, or what not by a war, or what have you. Then other people would start trying to re-explore the navigation routes. Perhaps there are reminants of the guild floating around. But no one individual has the whole picture of the routes.

Could be a good start on the concept of the lost earth.

This would make sense. The smaller the redundancy ratio, the more likely data can be lost. My objections above are entirely based on massively redundant and widespread databases to begin with. Change that variable and all bets are off.

-clash

Quote from: estar;356606Like Ur and Babylon? While knowledge of their existence persisted it wasn't until 19th century archeologists started digging that they were found again.  

Barring some catastrophe the a likely scenario is that planet will still be inhabited but the fact that it was Earth, the cradle of humanity would be lost.  

What it would take to do that is not any particular aspect of stellar cartography but a dark age where human knowledge is lost. Then later regained. If there are no dark ages then I agree with Clash that there is little chance that Earth's location would be lost.

Ur and Babylon's location were lost because of a multitude of changes that occurred in Mesopotamia leading the locations to be abandoned and then later forgotten.  It has not happened to Rome or most of the Greek cities yet. But it possible the location of some of the older Greek City-states that were abandoned (Sparta for example) could be lost if a dark age fell on our civilization.

Even if Earth was lost there the idea that the region was humanity's cradle would likely persist.

Ur and Babylon were lost because their locations were not plugged into a massively redundant and widespread database. Human memory is far to capricious to be depended on in such matters.

-clash

Battlestar Galactica?