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In a world like ours in the 1980s, but which for whatever reason does not use any form of electricity. (Either it does not exist or batteries and generators etc have not been invented.) For purposes of the question, diesel engines can be assumed (so no need for electric spark plugs or a replacement).

How would people construct a car headlight without electricity? Is this plausible to do or would using cars at night just be dark and dangerous?

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This question asks for hard science. All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See the tag description for more information.

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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – James Apr 2 at 21:09
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    $\begingroup$ Just wondering how it can be "like ours in the 1980s" without electricity? In what sense is it like the 1980s? $\endgroup$ – colmde Apr 3 at 11:20
  • $\begingroup$ @colmde In that all technology that does not depend on electricity is at that level (cars, motortools etc) and that the society is also similar in that goverment works mostly the same, the standard of living is mostly the same and people have homes that look the same $\endgroup$ – lijat Apr 3 at 11:23
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Back in the day before portable electric lights, carbide lamps were used: A mechanism dripped water onto carbide, which then gave off acetylene gas, which burned in a controlled fashion. This was used for headlights on cars and bicycles and for miners' lamps, even for lighthouse lamps. Hence, this is an obvious answer to your question.

enter image description here

Another option is to use magnesium flares, which among other things are used for underwater lighting.

Calcium carbide is typically produced in an electric arc furnace, but methods do exist to produce it without electricity, including a patented system for producing calcium carbide by providing heat directly through partial combustion of a powdery carbon-containing raw material and a powdery calcium-containing raw material in an oxygen-containing atmosphere.

Magnesium can be produced non-electrically by the Pidgeon process, a batch process in which finely powdered calcined dolomite and ferrosilicon are mixed, briquetted, and charged in retorts made of nickel-chrome-steel alloy. The hot reaction zone portion of the retort can be gas fired or coal fired

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    $\begingroup$ For Magnesium, use the Pidgeon Process. en.wikipedia.org/wiki/Pidgeon_process $\endgroup$ – Klaus Æ. Mogensen Apr 1 at 10:37
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    $\begingroup$ For calclum carbide, this patented process can be used: patents.google.com/patent/CA2730754C/en $\endgroup$ – Klaus Æ. Mogensen Apr 1 at 10:44
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    $\begingroup$ I see you kept going with the research... +1 $\endgroup$ – Don Qualm Apr 1 at 11:58
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    $\begingroup$ I went caving with school back in the 80s and early 90s, and we were still using carbide lamps. Torches with filament bulbs ran through batteries fairly quickly, and the bulbs were relatively fragile. If you're underground and wet, you aren't in a position to change a bulb or batteries. Carbide lamps had the great advantage that so long as you had carbide and water, you were basically sorted. $\endgroup$ – Graham Apr 1 at 16:27
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    $\begingroup$ Wouldn't magnesium flares blind oncoming traffic? Could lead to some interesting differences in city planning and infrastructure, though. All one-way streets, perhaps? $\endgroup$ – Jon.D. Apr 2 at 15:01
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The obvious retro answer would be to use carbide lamps which work by dripping water onto a chamber of calcium carbide producing acetylene as was used on the original versions of the Model T Ford:

enter image description here

Copyright Royce

CaC2(solid) + 2H2O(liquid) -> C2H2(gas) + Ca(OH)2(aqueous)

However, since the Calcium Carbide is made using an electric arc furnace, there may be no economically viable way to mass produce it in your world, so it might become the exclusive province of the rich.

Slaked lime (Calcium Hydroxide Ca(OH)2) Could be used to produce limelight. An Oxygen-Hydrogen flame is directed at a cylinder of the lime bringing it to a temperature of 4,662 °F (2,572 °C).

Part of the light output is black body radiation (incandescence), but part is candoluminescence giving off more light than otherwise in the green part of the spectrum.

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    $\begingroup$ I think the extra explanation for how the process works makes this the best option to choose as the correct answer. $\endgroup$ – Parrotmaster Apr 1 at 9:43
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The question of what people would do in the 1880's without electric headlights is not hypothetical. Electric headlights were not, in actuality, invented until the 1890's.

From Wikipedia:

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  • $\begingroup$ What does this have to do whit the question that asks about 1980s? $\endgroup$ – lijat Apr 1 at 15:00
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    $\begingroup$ @lijat, actually, this answers the question very neatly and the historical reference to a working solution is exactly the kind of substantiation we like to see here. Well done, Jon. $\endgroup$ – JBH Apr 1 at 15:02
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    $\begingroup$ It answers the question "how could we have working headlights without electricity," which is the main focus of this post. I don't think it matters when it was invented, really. Instead, the important fact is that it was a working system that was put into production. Others have mentioned the chemical reactions, raw material extraction processes, and more scientific parts of the answer. I think this one brings a more 'common' historical perspective that may be appreciated by less science minded readers. $\endgroup$ – Skeptycal Apr 1 at 16:50
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    $\begingroup$ @lijat Yes, the acetylene lamps certainly would be. The carbide lamps in other answers also burn acetylene, so it is the same light. Just a different way of storing it. But of course that also means this is not really a separate solution, just another argument why acetylene is probably what you want. $\endgroup$ – Ville Niemi Apr 1 at 18:02
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    $\begingroup$ Please quote the text properly instead of linking an image, which doesn't even link back to the correct source. "Wikipedia" is not a proper citation. $\endgroup$ – Polygnome Apr 1 at 19:25
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Since you're talking about diesel engines, you could also use diesel as lamp fuel.

It doesn't burn particularly cleanly and in cold weather it will need to be preheated to work, so far from perfect but it does save you from using multiple different fuels for different parts of the vehicle.

Other options include oil, gas, and alcohol. Just about anything that will burn can be used for lighting, it's merely a matter of lamp design. In some cases you'll need to pressurise your fuel, you'll need a suitable mantle, and an ignition system (like a chauffeur).

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    $\begingroup$ Can disel burn brightly enough to use for headlamps, considering that even a large fire like a camp fire only gives s few meters of visibility. $\endgroup$ – lijat Apr 1 at 8:37
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    $\begingroup$ That's a matter of reflector design. A normal 12v car bulb alone isn't particularly bright, but the parabolic reflectors focus the light into a much more usable beam. Of course none of these options are comparable to a modern LED bulb, but then headlights in the 70s and 80s weren't up to much either. $\endgroup$ – Separatrix Apr 1 at 8:39
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    $\begingroup$ @Separatrix Car headlights in the 70s and 80s were perfectly adequate to drive at legal speeds (i.e. 70 mph). In fact many cars still use exactly the same incandescent bulbs as were used back then. LED car lights are mostly a marketing gimmick, not a necessity. Back in the 70s I regularly did 200 mile drives in 3 hours, at night in the UK. $\endgroup$ – alephzero Apr 1 at 10:38
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    $\begingroup$ @Separatrix: Not (just) a matter of reflector design. What you need is a mantle that glows intensely when heated by the nearly colorless gas flame. This is how old gas lighting worked, as well as the Coleman-style camping lanterns: home.howstuffworks.com/gas-lantern2.htm $\endgroup$ – jamesqf Apr 2 at 3:26
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    $\begingroup$ @alephzero: LED headlights aren't really (or at least entirely) a marketing gimmick. Even when they only produce as much light as incandescent lights, they use less power (thus increasing fuel economy), and are more reliable. None of my current vehicles use LED headlights, yet are perfectly adequate for night driving. Indeed, a major problem is that LEDs are often too bright, and blind oncoming traffic - especially since all too many seem to have never managed to locate the low beam switch in their cars. $\endgroup$ – jamesqf Apr 2 at 3:33
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The car could be powered by a Diesel engine that gets started similar to a Lanz Bulldog. (pre-heat with a fire (wood fire, gas burner, coal, ...), then hand-crank). There are Youtube videos about the process.

The headlight could be Petromax type burners (they can run on Diesel just fine). Just use the basic Petromax construction, then add a reflector to direct the light.

That type of headlight might have trouble getting road-legal in Germany because... too bright!

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Are you fixed on having headlights on the vehicle?

We don't require headlights during the day because its not dark. So give your world 24 hour sunlight or the equivalent. That would be another reason for not needing electricity for other purposes.

Or consider having roads well-lit by fixed illumination, like gas lamps with fixed piping supplies, or lots of menial workers whose job is to light the lights at dusk.

Or alter the physiology of the eyes of your characters so they have more Rods and fewer Cones, and can therefore see better in the dark like a cat or dog. Downside of this is a reduction in colour perception. A large moon orbiting directly opposite the sun would provide some base level of illumination all night long.

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    $\begingroup$ This is an answer, in a "out of the box" way that services the question but from another direction. Kinda bends "world like ours" though. $\endgroup$ – Criggie Apr 1 at 18:17
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    $\begingroup$ That would not fit the concept, this was but a little pice of the whole pussel but one I had not figured out yet $\endgroup$ – lijat Apr 1 at 18:32
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Stop driving

...at night.

In a world without electricity, artificial lighting is going to be pretty lousy. Downtown areas will have gas lighting, but outside that core, there will be miles and miles of ordinary residential/light business districts that don't rate gaslights, but still don't want cars tearing through their neighborhoods at 30 mph in the dark.

And while headlights are achievable (though not all that great), taillights present a much harder problem. A light that small will be difficult, especially when it also needs to be more reliable than a headlight - you notice when a headlight goes out. So taillights may be impracticable, and cars would be pitch black aft.

Between the risk of overrunning an unmarked car ahead, and hitting pedestrians, "overdriving your headlights" would be serious business. Governments would impose draconian nighttime speed limits with stiff consequences for night speeding. So driving at night would be deathly slow, to the point of not being worth doing, except to "limp home" at a dreadful pace after an unexpected delay.

This would happen early in the evolution of automobiles, and stick.

Obviously, over the decades things would improve; roads would get better, those outer-urban and suburban neighborhoods would get gas lighting on their major trunk routes (e.g. In your town, all the numbered routes), and limited-access freeways would be built with more liberal nighttime speeds due to absolute prohibition of pedestrians. But that would only help after you get to the freeway. Until then, you're still plotzing along at 10-15 mph on the neighborhood and feeder routes that are 30-45 mph by day. It would be just too tedious. Nobody would have the nerves for it.

Except of course for commercial interests; trucks and buses, which are expensive machines with the best lighting money can buy, would own the night.

Trains and streetcars would also be tip-top. Even in our world, trains always had the best headlights available. In fact, this "ability to move at night" would slow the decline of rail transit. Fair chance the Interurbans are still around, providing swift travel on their limited-access right-of-ways (with a hiking-biking trail alongside to remove the temptation to walk down the tracks). If you were trapped downtown after dark, just as likely you'd leave your car downtown and take the interurban home. No electricity, yes; but the streetcars and interurbans would happen a bit later and have diesels.

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    $\begingroup$ Plausible detail, yet negated by all the other answers about non-electric lighting that has already been actually used. $\endgroup$ – WGroleau Apr 2 at 2:53
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    $\begingroup$ You don't need tail-lights. If you've got headlights, you can use retroreflectors instead. $\endgroup$ – Mark Apr 2 at 21:19
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    $\begingroup$ @Mark what about break lights? $\endgroup$ – wjousts Apr 5 at 14:09
  • $\begingroup$ @wjousts experience has shown how important brake lights are, and that two is not enough. The constant night rear-enders will only go to show people are overdriving their headlights and night speeds need to stay low. $\endgroup$ – Harper Apr 5 at 15:23
  • $\begingroup$ @WGroleau because you don't snap your fingers and get to modern day. This will evolve over a century, and in much of that century, quality headlights will be too expensive, and the laws and social norms will have their feet firmly planted in the past. Now that we're here, smog laws may have something to say about fuel headlights. $\endgroup$ – Harper Apr 5 at 15:24
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For something a bit more fantastical than chemical lamps: how about some fireflies or similar bio-luminescent life forms trapped in the headlights and forced to glow?

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