The Voyager disk contained a "map" showing where Earth is. They used pulsars to identify Earth's location. However, since the launch of Voyager we've discovered that there are probably a billion pulsars in the Milky way. We've also discovered that they somewhat unpredictably change the direction in which the pulses are directed. Making it unlikely that Earth's location can be identified using this map.
Nice article, shame about the invasive Ads Forbes uses...
Sometimes I wonder if the decision to turn Voyager around to produce the photo of the "pale blue dot" will someday end up fucking with aliens who couldn't imagine another species who would launch a deep space probe backwards.
New Horizons had a different design and works more like you describe; where the whole probe has to turn to point the camera.
Spoiler: One of the central tenets of this book is that the most logical course of action for any alien discovering another life form, is to destroy it immediately. The story is pretty coherent, but if anyone has references to any scientific/theoretical work on this I'd be very interested in reading it.
1. Destroying a civilization isn't risk free. If you destroy a nearby star system that harbors life, you better be sure that your weapon can't be traced back to you, by either any observers, or by the survivors. (See Forge of God & The Anvil of the Stars[1] for a study of the latter.)
2. If you do subscribe to the Dark Forest game theory, and do have what you believe is an untraceable weapon of some kind, there's no reason not to sterilize every star system around you. Why would you wait until you've detected life? Send out self-replicating Saberhagen Berserker[2] probes and sterilize the galaxy. (Be sure you've got a good Friend-or-Foe system in place.)
[1] https://www.goodreads.com/book/show/464609.Anvil_of_Stars [2] https://www.goodreads.com/book/show/582675.Berserker
The Strugatsky brothers book "Roadside Picnic" (inspiration for game and movie "Stalker") is based on the idea that aliens came and visited Earth and ignored us completely.
However, they left behind a lot of weird and often deadly trash that people are scavenging.
Civilization inhabiting whatever their favorite star systems in the galaxy would have to deal with a few problems. One is that the size of the galaxy (100k light years) galaxy wide quite difficult. Another problem is that civilizations can go from pre-radio (before they are easy to detect) to mass energy conversion (allowing a decent fraction of light speed) within a few 100 years. One likely strategy would be to place sensors across the galaxy that would detect problematic aggressive/warlike civilizations and eliminate them.
So civilizations that are peaceful, grow slowly, don't ruin their planet, and don't set off nukes in their atmosphere might get a pass. Maybe even an invitation into the galaxy wide community once they figure out anti-matter/mass conversion.
However the ones launching nukes might just get eliminated before they become hard to contain. If the typical window from pre-ratio to a growing thread takes a minumum of 200 years they might well spread a sensors to be within 100 light years of any planet. That would need something like 250k to cover the milky way. That way the problem is eliminated within 200 years and before they can spread far enough to be hard to contain.
New mathematics, new ways to see physics, new art and culture, etc. and most of it would have been nearly impossible to create de novo. An easy solution to prime number generation? Easily worth Italy in value, if not more, over the medium-long term. Multiply that by a planet and all of it's history.
Hell, the dumb accounting records of even a small municipality for a few decades from aliens would be worth at least a Luxembourg in terms of information you could glean from it. (Not to make it all about money, but to give the info some sort of value we can understand) An alien civilization would be astonishing in terms of it's value to science and culture, etc. Forget BC or AD in terms of marking time, it would be Pre-Contact and Post-Contact.
Why kill that? Why destroy the golden goose? That would be so stupid.
Ok, maybe come in in disguise, give them an internet type thing, glean every possible bit of data from it, then sterilize the civilization. Best of both worlds? (pardon the pun).
Still, the matter we are made of is only ~5% of the universe. Dark matter is about 20% and dark energy is about 75%. So, odds are that whatever the aliens are doing, it's in those realms. Realms we cannot even begin to think to access and modify yet. If anything, if they see us, we're acting like a goldfish stuck in a bowl to them, no threat whatsoever.
In that case i'd rather be destroyed than share a universe with such a species. I do not think the premise makes sense. It also makes no sense to compare it with the slaughter of native americans, since that has been done by apes in clothes.
Any interstellar spacefaring civilisation should be so advanced that it values construction over destruction.
Unless they already orbit all 100 billion stars, but even then it's 100,000 years to collect the data.
Basically with 200k pulsars sprinkled among 100B stars sprinkled over 200,000 light years it's very easy to get lost. A list of frequencies gets less useful over time. You saw a pretty big difference in the data between 1969 and 2002. Imagine the differences in 100k years.
Even a single unknown gravitational interaction could throw the probe way off in speed/direction.
With a computer and observations of "a fair percentage" of the 14 original pulsars, it would still be "fairly easy" to determine which pulsars we're talking about, because from the period alone, you can reduce the total number of candidates to a handful. And so from 200,000 pulsars, from the original 14 period measurements (or 11 in the case of my tattoo), you should be able to reduce the total pulsar pool down to perhaps a hundred or so candidates, just from looking at reasonable possible pulsar periods. Then you can permute through all combinations using a computer to determine which of the pulsars all shared the particular recorded period values at the same time. These values are so precise, and so varied in nature, that you could easily take all 200,000 pulsars in the galaxy, and sort out which 14 you were talking about, if you also could guess that the 14 values were all measured at the same time, that the precise moment chosen to record the period value had to coincide with the precise moment chosen for the other 13 pulsars. Only this select group of 14 pulsars will have had these precise period values at one time, even if many other pulsars in the galaxy have had a specific period value at some point in their history, and this is the genius of Carl Sagan's idea, since you then also can encode a specific time in the data (which happened to have been Voyager's launch date on the golden record, and my birthdate in my tattoo). I still concede that along enormous time scales, it would not be possible to do this, but Carl Sagan's original assertion is definitely not unreasonable across the span of a few million years or so, and a reasonably large enough survey of the galaxy.
So this is actually how the map "encodes" the launch date of the Voyager probe (and how I was able to change this data and encode my own birthdate in my tattoo): We measure the period of a pulsar at a specific point in time. The pulsar above with period 0.34567890 is a specific period that will change over time due to the natural slowing of its spin (it's p-dot). So all the periods "encoded" into the original map were December 1969. I identified the pulsars, updated the data (distance, direction) with data from the new sky surveys, then advanced the pulsar period value by the p-dot value between December 1969 and the precise date of my birth, then re-encoded those new period values into binary, placed them on the "new" map with updated direction and distance data, and got the tattoo.
I discovered all of this stuff in the research phase of my tattoo. I had some discussions with a handful of professors in the Astronomy department at UH -- where I was going to school at the time -- and for a time it became this "thing" that was well-known in the department. I'd go visit someone for the first time casually during their office hours and they'd mention they'd heard of my idea. Probably one of the best compliments I ever got was from an old engineer that had worked on the SSME (Space Shuttle Main Engine, one of the most complex machines ever made) who said that my tattoo was the nerdiest thing he'd ever seen. Felt good man.
If you're standing on top of your cache, sure, the map makes sense, but if you're anywhere else at all, you would need to map every tree in the forest, and run a pattern recognition algorithm on them, hoping that none of the key trees have blown down or burned since the map was made.
40 years ago, we launched a probe with what we though as of then as being a nice, permanent map of our location. Since then, we learned that there are many more 'beacons' in the universe than those we have chosen and pointed out in our 'map', and they change randomly or pseudorandomly, so with our current knowledge, receiving such probe with such map, we would be SOL to decode it.
But, 40 years ago, there was a term 'supercomputer' which meant an 80 MHz, 5 ton, >100 kW-eating monster. Nowadays, we carry billions of 150 gram glass slates in our pockets with 100-times the computing power, use it to play games, and we throw around desktop/rig computing power to shift balances between virtual bank accounts (PoW-based cryptocurrencies). What would be an unthinkable feat on the planet-wide energetic and hardware level back than, a grad student can do on their gaming device (CUDA etc.) nowadays as a semestral project, building on existing open-source libraries and published reproducible research.
What will be possible [on our humanity scale] in another 40 years? 400 years? 40000 years?
Wouldn't they just intercept the probe and immediately think, oh, species 5618 thought back then that a dozen of pulsars engraved on a metal disk would make a good map, how cute, let's run a configuration-search on our astronomical recordings and on next orbital period, a PhD student presents an interstellar-conference paper on three possible locations in the known history where and when the species 5618 would observe just this specific pulsar configuration recorded on the probe... Ok, what if they started recording the observable universe only after we recorded our map? They may not have the exact stellar configuration in their big data clouds, but using SETI-like-network, in another orbital period, they will simulate historical pulsar configurations back before they started recording them and extrapolate similar results. This is just a 'linear' prediction on our technology, but what about a complete paradigm shift? What if they can browse in a block universe just like we page through a book and can just rewind and fast forward looking in the spacetime searching for the configuration recorded on the probe?
Or, we will develop FTL in tens/hundreds/thousands of years, overtake the Voyager with spacecraft just like taking off a private Cessna at a local hobby airport, grab it as a historical artifact for the museum and launch a better map, or, we would know better by then and rather quietly destroy it, remain silent and be thankful it wasn't seen by anything (Hawking's position on contacting alien life).
An earth bound semi-fictional example: Say a secluded culture thinks that recording rains, droughts, good and bad harvests will benefit their children. Some time later they will find that they have a full Library of Alexandria of records and noone, never ever, in many human lives would sift through all the recordings to find anything useful. Some more time later they will even find about climate zones and think that their collected records are truly worthless and useless. On the other hand, if our current selves find such records - if they are fairly recent, we have complete satellite imagery of the place. We have pretty nice worldwide temperature, rain, air pressure recordings. If it is a bit older, we still have more sparse weather records, so with some effort, we can still search for their rain-drought patterns. We can carbon date it. We can or cannot see our atmospheric nuclear tests in their smelting. We can digitally cross-reference digitized historical written records from many cultures (probably not now, mind you, semi-fictional). We can manually cross-reference their observations with known folklore from around the world. We can drill Antarctica/permafrost layers to evaluate climate back then. We can date it before/after/around great extinction events, geological eras at least...
Just because we just realized that the IRL situation is much more complex than we thought, it doesn't mean that what we recorded back then and sent out is "hopelessly wrong" [and useless].
UHF television broadcasts fare even worse because they have a much wider bandwidth and an even greater free space path loss.
We quickly learned that blasting long-wave analog voice signals to the skies and expecting the reflection behind the horizon is pretty inefficient and moved to shorter, shorter and shorter waves. Not only you don't need to blast local radio stations in local language to the other side of the planet, having hundreds of computer wireless networks in one apartment building means that it actually shouldn't broadcast more than a few walls away in order for multiple networks to coexist even with time-division multiplexes and collision avoidance magic.
So, in about a hundred years, we discovered RF, we then started by blasting long-wave radio stations using ionosphere as a mirror, gradually moved to more and more local frequency bands, we then launched satellites to wirelessly ping across the ocean, only to hide the signals back under the sea and ground using fiber optics for practical reasons (bandwidth, latency), we went from analog to digital and we started encrypting just about everything. In the end, we will produce mostly random noise with ultrashort reach.
Next step - we will enclose Sol with Dyson sphere and disappear completely :)
Basically how far away could the most power signals from earth be heard?
Should be several magnitudes more powerful than a FM broadcast, while being significantly lower bit rate.
(for those who haven't seen it, 'they' receive images dating from the 1930s or thereabouts with a certain someone making what is today, an unacceptable (for most of us one hopes) salute)
V'ger is found in the middle of space utterly lost.
