If all humans died, when would the last light go out?
Summary
TLDRIn a hypothetical scenario where humans vanish, the majority of artificial lights would extinguish quickly due to power grid failures. Nuclear reactors might persist, but automatic shutdowns would ensue upon grid failure. Off-grid sources like diesel generators could last days to months, while geothermal plants might operate for years before succumbing to corrosion. Wind turbines could endure for decades, and solar-powered lights, especially in remote areas, could potentially be the last to go, shining for a century if maintained. Intriguingly, the glow from radioactive waste, such as cesium-137, could outlast all other light sources, persisting for centuries as a haunting reminder of human presence.
Takeaways
- š Without human intervention, most artificial light sources would go out quickly as power grids fail.
- āļø Fossil fuel plants would shut down within hours due to the lack of human-operated supply chains.
- š Nuclear reactors could theoretically run indefinitely with their fuel, but automatic safety measures would likely shut them down.
- š Geothermal plants might operate for a few years without maintenance, but would eventually succumb to corrosion.
- š¬ļø Wind turbines are designed for minimal maintenance and could last decades, but would eventually stop due to mechanical failure.
- š§ Hydroelectric generators could continue running for several years without human intervention.
- š Battery-powered lights would be off within a few decades due to self-discharge and lack of maintenance.
- āļø Solar power is a promising long-term light source, with the potential to last a century if properly maintained.
- š§Ŗ Spent nuclear fuel emits Cherenkov radiation, which could provide a faint glow for centuries due to the half-life of radioactive materials.
- šÆļø The last light on Earth might come from the glow of radioactive waste, outlasting all other artificial light sources.
Q & A
How long would it take for the last artificial light source to go out if humans disappeared?
-It's difficult to give an exact time frame as it depends on various factors, but some light sources could last for centuries.
What would happen to the major power grids without human intervention?
-The major power grids would likely experience a rapid series of cascading failures leading to a blackout within the first few hours.
How would fossil fuel plants be affected by the disappearance of humans?
-Fossil fuel plants would start shutting down in the first few hours due to the lack of a steady supply of fuel and human intervention.
What is the potential longevity of nuclear reactors without human operation?
-Nuclear reactors could theoretically run indefinitely with a settled core, but most would automatically shut down if something went wrong.
How long could diesel generators in remote communities last without refueling?
-Diesel generators could run until their fuel tanks are empty, which could be anywhere from days to months.
What is the expected lifespan of geothermal plants without human maintenance?
-Geothermal plants might run for a few years without maintenance, but would eventually succumb to corrosion.
How long could wind turbines operate without regular maintenance?
-Modern wind turbines are typically rated to run for 3 years without servicing, but some could potentially last for decades.
How long would generators that convert falling water into electricity continue to work?
-Generators converting falling water into electricity, like the Hoover Dam, could run on autopilot for several years.
What is the expected lifespan of battery-powered lights without human intervention?
-Battery-powered lights would all be off in a few dozen years due to self-discharge, regardless of usage.
How long could solar-powered lights last in remote locations?
-Solar-powered lights could potentially last for a century if the panels are kept free of dust and the electronics are well-built.
What is the potential longevity of Cherenkov radiation from radioactive waste?
-Cherenkov radiation from radioactive waste, such as cesium-137, could still be glowing with 1% of its original radioactivity two centuries later.
Outlines
š” The Fate of Artificial Light After Humanity's Disappearance
This paragraph explores the hypothetical scenario where all humans vanish, and the subsequent impact on artificial light sources. It begins by noting that most lights would extinguish quickly due to the collapse of major power grids. However, some sources like nuclear reactors could continue running indefinitely due to their fuel's longevity, despite the likelihood of automatic shutdowns due to grid failures. The paragraph also discusses the varying lifespans of different power sources such as diesel generators, geothermal plants, wind turbines, hydroelectric generators, battery-powered lights, solar power, and even radioactive waste, which could glow for centuries due to Cherenkov radiation.
Mindmap
Keywords
š”Artificial Light Source
š”Power Grids
š”Fossil Fuel Plants
š”Nuclear Reactors
š”Off-Grid Generating Stations
š”Geothermal Plants
š”Wind Turbines
š”Battery-Powered Lights
š”Solar Power
š”Cherenkov Radiation
š”Cesium-137
Highlights
Major power grids would go down quickly without human intervention.
Fossil fuel plants require a steady supply of fuel and would shut down in the first few hours.
Nuclear reactors could run almost indefinitely with their current fuel, but would likely shut down automatically due to grid failure.
Diesel generators in remote communities could run for days to months until fuel runs out.
Geothermal plants might operate for a few years without maintenance before succumbing to corrosion.
Wind turbines are designed for minimal maintenance and could run for decades.
Hydroelectric generators could continue running on autopilot for several years.
Battery-powered lights would be off in a few dozen years due to self-discharge.
Solar power is a promising candidate for long-term light sources, especially in remote locations.
Solar panels could provide power for a century if kept clean and in dry conditions.
Spent nuclear fuel can emit light through Cherenkov radiation, potentially lasting centuries.
Cesium-137, used in nuclear waste, has a half-life of 30 years and could still glow with 1% of its original radioactivity after two centuries.
The distinctive blue glow of nuclear reactor cores is due to Cherenkov radiation.
Radioactive waste products can be a long-lasting light source due to their radioactivity.
The light from radioactive materials will fade in brightness over time but maintain the same color.
In the absence of humans, the last light sources could be from solar-powered lights or radioactive waste.
Transcripts
This question comes from Alan, who asks:
If every human somehow simplyĀ disappeared from the face of the earth,Ā Ā
how long would it be before the lastĀ artificial light source would go out?
We'll start with the obvious:Ā most lights wouldn't last long,Ā Ā
because the major power gridsĀ would go down relatively quickly.
Without people, there wouldĀ be less demand for power,Ā Ā
but our fridges and air conditionersĀ and lava lamps would still be running.
Fossil fuel plants, which supply theĀ vast majority of the world's electricity,Ā Ā
require a steady supply of fuel, and theirĀ supply chains do involve people doing things.
As coal and oil plants started shutting down inĀ the first few hours, other power sources would getĀ Ā
hit with the extra load. This kind of situationĀ is difficult to handle even with human guidance.
And the result would be a rapidĀ series of cascading failures,Ā Ā
leading to a blackout ofĀ all the major power grids.
Nuclear reactors, of course, donātĀ require a steady supply of fuel:Ā Ā
one reactor operator I talked to said thatĀ if their core settled into low-power mode,Ā Ā
it could continue running almost indefinitely;Ā a cube of uranium contains about six millionĀ Ā
times as much stored energy asĀ a similar-sized cube of coal.
Unfortunately, although there's enough fuel,Ā most nuclear reactors wouldn't keep runningĀ Ā
for long. As soon as something went wrong,Ā the core would go into automatic shutdown.
Every part of a reactor control system is designedĀ so that a failure causes it to rapidly shut down.
This would happen quickly; manyĀ things can trigger shutdown,Ā Ā
but the most likely culprit wouldĀ be the failure of the power grid.
However, plenty of light comes fromĀ sources not tied to the major powerĀ Ā
grids. Let's take a look at a few ofĀ those, and when each one might turn off.
Many remote communities, like those on far-flungĀ islands, get their power from diesel generators.
These can run until their tanks run out of fuel,Ā Ā
which in most cases could beĀ anywhere from days to months.
Off-grid generating stations that don't need aĀ Ā
human-provided fuel supplyĀ would be in better shape.
Geothermal plants can run for a fairĀ bit of time without human intervention.
According to the maintenance schedule for theĀ Svartsengi Island geothermal plant in Iceland,Ā Ā
every six months the operators must change theĀ Ā
gearbox oil and re-grease allĀ electric motors and couplings.
Without humans to perform theseĀ sorts of maintenance procedures,Ā Ā
some plants might run for a few years, butĀ they'd all succumb to corrosion eventually.
Lights relying on wind powerĀ would last a bit longer. WindĀ Ā
turbines are designed so that theyĀ don't need constant maintenance,Ā Ā
for the simple reason that there are aĀ lot of them and they're a pain to climb.
The Gedser Wind Turbine inĀ Denmark was installed in theĀ Ā
late 1950s and it generated powerĀ for 11 years without maintenance.
Modern turbines are typically ratedĀ to run for 3 years without servicing,Ā Ā
and there are no doubt someĀ which would run for decades,Ā Ā
and one of them would probably haveĀ at least a status LED in it somewhere.
Eventually, most of the wind turbinesĀ would be stopped by the same thing thatĀ Ā
would destroy the geothermal plants:Ā Their gearboxes would seize up.
Generators that convert falling waterĀ into electricity will also keep working.
An operator at the Hoover Dam onceĀ said that if everyone walked out,Ā Ā
the facility would continue to runĀ on autopilot for several years.
Though if the power grid is down, allĀ that electricity would have nowhere toĀ Ā
go. In the end the dam would probablyĀ succumb to clogged intakes or the sameĀ Ā
kind of mechanical failure that hit theĀ wind turbines and geothermal plants.
Battery-powered lights wouldnāt fare muchĀ better, and will all be off in a few dozen years.
Even without anything using their power,Ā batteries eventually self-discharge.
Some types last longer than others, butĀ even batteries advertised as having longĀ Ā
shelf lives typically only holdĀ their charge for a decade or two.
Solar power is probably the most promisingĀ candidate. There are many off-grid solar-poweredĀ Ā
buildings, weather stations, and other remoteĀ infrastructure around the world. Emergency callĀ Ā
boxes, often found along the side of the road inĀ remote locations, are frequently solar-powered.
They usually have lights on them, which provideĀ illumination every night. Like wind turbines,Ā Ā
they're hard to service, andĀ they last for a long time.
Solar panels will generally last as longĀ as the electronics connected to them,Ā Ā
and as long as the panels areĀ kept free of dust and debris.
The wires and circuits will eventually succumbĀ to corrosion, but solar panels in a dry place,Ā Ā
with well-built electronics, could easilyĀ continue providing power for a century ifĀ Ā
they're kept free of dust by occasionalĀ breezes or rain on the exposed panels.
If we follow a strict definition ofĀ lighting, solar-powered lights inĀ Ā
remote locations could conceivably beĀ the last surviving human light source.
But there's another contender, andĀ it's a weird one: spent nuclear fuel.
Contrary to popular portrayals,Ā radioactivity isn't usually visible,Ā Ā
which is part of why we need warning signsĀ around areas with radioactive materials or waste.
Sure, watch dials used to be coated inĀ small amounts of radium to help themĀ Ā
glow in the dark, but the glow didn'tĀ come from the radioactivity itself.
It came from the phosphorescent paint on top ofĀ the radium, which glows when itās irradiated.
Once the phosphorescent paint breaks down,Ā Ā
the watch dials are stillĀ radioactive, but no longer glow.Ā
Watch dials, however, are not ourĀ only radioactive light source.
When radioactive particles travelĀ through materials like water or glass,Ā Ā
they can emit light throughĀ a sort of optical sonic boom.
This light is called Cherenkov radiation,Ā and it's seen in the distinctive blueĀ Ā
glow of nuclear reactor cores. Some of ourĀ radioactive waste products, such as cesium-137,Ā Ā
are melted and mixed with glass, which coolsĀ into a solid block before being wrapped inĀ Ā
more shielding for transport and storage. And in the dark, these glass blocks glow blue.
Cesium-137 has a half-life of 30 years,Ā which means that two centuries later,Ā Ā
the blocks will still be glowing withĀ 1% of their original radioactivity.
Since the color of the light depends only onĀ the particle decay energy, and not the amountĀ Ā
of radiation, it will fade in brightnessĀ over time but keep that same blue color.
And thus, we arrive at ourĀ answer: Centuries from now,Ā Ā
deep in concrete vaults, the light fromĀ our most toxic waste will still be shining.
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