79

You need more than dead. You need dead and weird. Interstellar spaces are huge. Ships need to be able to traverse these distances. The fact that there are clumps of matter - "dead worlds" - in between that are not useful to these ships should make no difference. It is like the fact that there are some empty office buildings on my route home. Who cares?...


57

Let's say your magical sphere has radius $r$ of 10km (so just poking up into the outer atmosphere) and is at a temperature $T$ of 1,250K (so glowing a nice warm yellow). The total radiative heat flux from the sphere is given by: $$ Q = \sigma T^{4}. 4\pi r^2 \approx 1.7 \times 10^{14} \mathrm{W} $$ Where $\sigma$ is the Steffan-Boltzman constant. A ...


45

Bells. A large (hence deep-toned) bell can be heard for many miles. Couple with a reflective sound concentrator as in @L.Dutch answer, and bells should be audible for about as far as you could see a lighthouse. "Wait, you can't hear individual sounds over a great distance!" Well, you can't now -- but the world was quieter before there were cars and ...


44

This is basically a variant of Willk's answer (it needs to be "dead and weird"). You specifically mention Star Wars technology, and I happen to know Star Wars uses "hyperspace" for its faster-than-light drives. A quick Google search confirms that Halo uses "slipspace", which is basically the same thing. In both cases, they rely on jumping from normal space ...


33

I'm kind of surprised that no one has mantioned the obvious time tested method of long range communication: Drums Lots of people have brought up using sound, and even the very clever use of acoustic reflectors, but Drums avoid many problems associated with things like guns (ammo ain't cheap, and how much bandwidth could you get out it). They are lighter ...


22

You already mention homing pigeons. Another alternative is to use sound and a suitably shaped reflector to focus the sound beam toward the receiver, who will in turn use a similarly shaped receiver to listen. Something similar was used during WW1, where acoustic mirrors were used to detect enemy planes flying toward England over the Channel. Since you are ...


17

Ropes You can build "physical telegraph" with manned relay stations a kilometer or two apart from each other using cables or hawsers. On one side a man plus a lever, on the other side a bell rings or some semaphore changes its state. There were even pilot (and not only pilot) projects of such kinds of communications, but the optical telegraph appeared to ...


12

You do realise you've just reinvented Terry Pratchett's "Clacks" system, don't you? Anyway, solutions... Put the towers closer together Over long distances, sure, weather is a problem. Over shorter distances though, bright lights will still be visible even though rain and fog, and the operators can drop their data rates to improve reliability. Of course ...


12

Estimates for the mass of the Chicxulub impactor that offed the dinosaurs range from 1015 and 4.6 $\times$ 1017 kilograms. The hydrosphere's mass is currently estimated to be around 1.4 $\times$ 1021 kilograms. That is like 10,000 Chicxulubs in terms of orders of magnitude, if we use the upper bound for Chic's mass. Might be more like 100,000 dino-killing ...


10

Yes, but it will depend heavily on the values of each civilization. A pragmatic society will only visit solar systems they expect to be worth the return on investment based on what they already know. They will do years of analysis for hazardous solar activity, scan for signs of existing civilizations, search for promising exoworlds, and send unmanned ...


9

So, lets say there's about $1.8*10^{21}$kg of water on the surface of the earth (this excludes hydrates and stuff in the mantle, but the surface stuff seems like the bit most likely to be deposited by impacts after earth's formation). Given the density of ice, $920kg/m^3$, that much water would form a solid sphere about 776km in radius. That's Quite Big, by ...


8

I found a nice history of warning signals from the US Lighthouse Society. The problem seems to be that the things, such as fog, that interfere with light also interfere with sound propagation. One of the possibilities that you should consider is that there will exist times with communication blackouts. In such times, a pony express type service for ...


8

There is no scenario in which the biosphere survives long. You have, at best, a few centuries. Say the fireball is as cool as possible while still being a fireball; 100 degrees celsius. All the oceans will continually drain towards the fireball and will boil on contact, as you said. This is bad news for your biosphere, because that's a huge amount of ...


8

I think that many Latin American or South American countries are a lot more developed and have more paved highways than you imagine. The Pan-American Highway1 is a network of roads stretching across the American continents and measuring about 30,000 kilometres (19,000 mi)1 in total length. Except for a rainforest break of approximately 160 km (100 mi), ...


7

Hydraulic Telegraph The use of hydraulics offers a few means of communication that would not be impacted by poor weather for the most part. And they can be build of relatively inexpensive wooden piping. How to actually send communications down a pipe can be done in several ways. If you can build your stations relatively level with one another [Such as ...


7

Homing pigeons provide a viable alternative, since although they may be slower they may carry considerably more information than a visual signal. They also posses an incredible range and are not dependent on line-of-sight. Precipitation and strong winds make flying impossible though, so communication via pigeon can only take place under very limited ...


7

Yes this is a realistic possibility. If Earth ever develops a probe that can travel long distances. You can bet we will pick a target where we think life exists, probably the direction that involves passing the most candidates as possible. If we find life, that will probably be where we focus all our efforts. So for your galactic civilizations, you just ...


7

You are basically cooking your planet on a stove. This magic fireball is an infinite source of heat, so it will sit there continually pouring heat into the planet's system. Water near it will be heated into steam, but the coolness of the water will not cool the fireball at all. This will cause the overall temperature to rise and rise until everything on the ...


6

Black Hole Drives If you have an interstellar civilization, presumably travel between stars is somewhat fast (i.e., weeks to months, rather than decades to centuries). None of the technologies we have today are remotely suitable for such interstellar travel. Nor have you stated how hard-science you want your drive technology to be. But if you want ...


5

FOG1 Should FOG1 look like Venus, it is because it will in some aspects be similar to it and because this is an image of Venus. :) FOG1 is a predomenetly metallic (read 90%+) super-earth orbiting a long lived, dim K-Type star. Its planetary attributes are: $$M = 7,5 Me$$ $$R = 1,3871 Re$$ $$gravity = 3,898 G (38,228 m/s^2)$$ $$Vescape = 26 km/s$$ Its ...


5

Silbo Gomero This is the whistling language used in the Canary Islands to communicate complex messages for distances of up to 5 km. The language requires skills, but no equipment. It should get through fog pretty well. Another answer mentioned whislting in Andorra, but the Canary Islands are more widely known for this. https://en.wikipedia.org/wiki/...


5

[Handwavium explanation] Without Oxygen, you will have a hard time burning the hydrogen to create a fire. Since you do not mention the composition of atmosphere, one possible way you can achieve the Firestorm could be via a sudden outburst of oxygen in the atmosphere leading to the right conditions, which are otherwise absent. This could be due to ...


5

No Refueling stations for spaceships will be in space. Too much fuel is lost going up and down a gravity well. A dead world is perfectly fine and might be a good source of fuel making material. Even empty space is fine as long as fuel haulers keep it restocked. An asteroid belt could also work. A refueling station can be anywhere but preferably near fuel ...


5

The fundamental problem is that there won't be an ocean left. And evaporating the ocean will destroy the biosphere from the heat. The bottom of the ocean is 1000 bar of pressure. To stop the ocean from flowing in, you need 1000 bar of steam, which requires near star-core scale temperatures (400,000 K). And then you have a star on your planet, which means ...


4

Signal Flares A little basic knowledge of gunpowder is all you need to make a signal flare that can be visible from a great distance even in the daytime. There are even chemicals you can mix in to make a number of different colors of flares. You'd have limited bandwidth for what kinds of messages you could send, but you could elaborate by sending multiple ...


4

Whether you use light or sound, weather is going to get in your way. While sound is able to bypass a fog, it's easier to put a visual system on a hill to have line of sight above low lying fog. Visual communication is far more reliable over distance, visual recognition is more efficient than listening out for audio signals - at least when we are not trying ...


4

A deep ocean society relies upon geothermal energy to live. What if, for reasons that don't have to be explained anytime soon in the story, the geothermal energy subsides to nothing at the ocean floor? Without energy, the community becomes unsustainable and has to go to the surface to get the energy needed to make food and sustain civilization. So, they ...


4

To gauge the impact of a steam-powered World on the environment just look around you: because... We live in a steam-powered world Three quarters of the electric energy produced in our real world is produced by steam turbines. Boil water (using coal, gas, oild nuclear, whatever), make steam, steam turns turbine, turbine turns generator. That shiny new Tesla ...


4

Steam is generated by burning some kind of fuel -- wood, coal, or petroleum. Right? If this is the case, the results will be little different from the world we have now, except that the smaller population and reduced coverage will limit the effects. That said, wood and coal are much more prone to produce solids (soot and ash) in their end products than ...


4

The decay and detritus of the surface dwellers is beginning to impact their society. Leaking nuclear waste, mass mutating bioweapons, ash, all these things are threatening their own way of life. So they send expeditions up to the surface to explore our ruins, fix our leaking waste and scrub radiation, destroy our bioweapons. This would only really need ...


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