If all humans died, when would the last light go out?

Summary

In 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

• 🌐 Without human intervention, most artificial light sources would go out quickly as power grids fail.
• ⚙️ Fossil fuel plants would shut down within hours due to the lack of human-operated supply chains.
• 🔋 Nuclear reactors could theoretically run indefinitely with their fuel, but automatic safety measures would likely shut them down.
• 🏭 Geothermal plants might operate for a few years without maintenance, but would eventually succumb to corrosion.
• 🌬️ Wind turbines are designed for minimal maintenance and could last decades, but would eventually stop due to mechanical failure.
• 💧 Hydroelectric generators could continue running for several years without human intervention.
• 🔋 Battery-powered lights would be off within a few decades due to self-discharge and lack of maintenance.
• ☀️ Solar power is a promising long-term light source, with the potential to last a century if properly maintained.
• 🧪 Spent nuclear fuel emits Cherenkov radiation, which could provide a faint glow for centuries due to the half-life of radioactive materials.
• 🕯️ 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

00:00

💡 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.

Keywords

💡Artificial Light Source

Artificial light sources refer to man-made devices that emit light, such as lamps, streetlights, and electronic displays. In the context of the video, the discussion revolves around how long these sources would continue to function if humans were to suddenly disappear. The video explores the various types of artificial light sources and their dependency on human maintenance and power grids.

💡Power Grids

Power grids are the interconnected networks that deliver electricity from power plants to consumers. The video explains that without human intervention, these grids would quickly fail due to the lack of fuel supply and maintenance, leading to a rapid shutdown of electricity distribution and, consequently, the熄灭 of most artificial light sources.

💡Fossil Fuel Plants

Fossil fuel plants are power stations that generate electricity by burning coal, oil, or natural gas. The script mentions that these plants would start shutting down within the first few hours of human disappearance due to the immediate cessation of fuel supply and the inability to manage the extra load on the power grid.

💡Nuclear Reactors

Nuclear reactors are facilities that use nuclear fission to generate heat, which is then used to produce electricity. The video highlights that while nuclear reactors do not require a constant supply of fuel, they are designed with safety measures that would automatically trigger a shutdown if any malfunction occurs, thus ceasing the production of electricity.

💡Off-Grid Generating Stations

Off-grid generating stations are power sources that are not connected to the main power grid and operate independently. The script discusses how these stations, particularly those using geothermal or wind power, could continue to function for an extended period without human intervention, as they do not rely on a continuous supply of fuel.

💡Geothermal Plants

Geothermal plants generate electricity by tapping into the Earth's internal heat. The video explains that while these plants can operate for a considerable time without human maintenance, they would eventually fail due to factors like corrosion, which would prevent them from generating electricity.

💡Wind Turbines

Wind turbines are devices that convert the kinetic energy of wind into electricity. The script mentions that wind turbines are designed to require minimal maintenance and can operate for years without servicing, making them a potential long-lasting source of power for artificial lights.

💡Battery-Powered Lights

Battery-powered lights are lighting devices that rely on stored electrical energy in batteries. The video notes that even without use, batteries will eventually discharge, leading to the eventual extinguishing of battery-powered lights within a few decades.

💡Solar Power

Solar power is electricity generated from sunlight using solar panels. The script suggests that solar-powered lights, especially those in remote locations, could be among the last light sources to go out due to their ability to function independently of the power grid and their longevity, provided the panels are kept clean.

💡Cherenkov Radiation

Cherenkov radiation is a form of light emitted when a charged particle passes through a medium at a speed greater than the speed of light in that medium. The video discusses how this phenomenon is observed in nuclear reactor cores and could be a source of light from radioactive waste products, potentially lasting for centuries.

💡Cesium-137

Cesium-137 is a radioactive isotope used in the video as an example of a material that could emit light due to Cherenkov radiation. The video explains that its half-life of 30 years means that even after two centuries, the cesium-137 would still be radioactive and capable of emitting a faint glow, making it a potential long-lasting light source.

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 simply  disappeared from the face of the earth,  

how long would it be before the last  artificial light source would go out?

We'll start with the obvious:  most lights wouldn't last long,  

because the major power grids  would go down relatively quickly.

Without people, there would  be less demand for power,  

but our fridges and air conditioners  and lava lamps would still be running.

Fossil fuel plants, which supply the  vast majority of the world's electricity,  

require a steady supply of fuel, and their  supply chains do involve people doing things.

As coal and oil plants started shutting down in  the first few hours, other power sources would get  

hit with the extra load. This kind of situation  is difficult to handle even with human guidance.

And the result would be a rapid  series of cascading failures,  

leading to a blackout of  all the major power grids.

Nuclear reactors, of course, don’t  require a steady supply of fuel:  

one reactor operator I talked to said that  if their core settled into low-power mode,  

it could continue running almost indefinitely;  a cube of uranium contains about six million  

times as much stored energy as  a similar-sized cube of coal.

Unfortunately, although there's enough fuel,  most nuclear reactors wouldn't keep running  

for long. As soon as something went wrong,  the core would go into automatic shutdown.

Every part of a reactor control system is designed  so that a failure causes it to rapidly shut down.

This would happen quickly; many  things can trigger shutdown,  

but the most likely culprit would  be the failure of the power grid.

However, plenty of light comes from  sources not tied to the major power  

grids. Let's take a look at a few of  those, and when each one might turn off.

Many remote communities, like those on far-flung  islands, get their power from diesel generators.

These can run until their tanks run out of fuel,  

which in most cases could be  anywhere from days to months.

Off-grid generating stations that don't need a  

human-provided fuel supply  would be in better shape.

Geothermal plants can run for a fair  bit of time without human intervention.

According to the maintenance schedule for the  Svartsengi Island geothermal plant in Iceland,  

every six months the operators must change the  

gearbox oil and re-grease all  electric motors and couplings.

Without humans to perform these  sorts of maintenance procedures,  

some plants might run for a few years, but  they'd all succumb to corrosion eventually.

Lights relying on wind power  would last a bit longer. Wind  

turbines are designed so that they  don't need constant maintenance,  

for the simple reason that there are a  lot of them and they're a pain to climb.

The Gedser Wind Turbine in  Denmark was installed in the  

late 1950s and it generated power  for 11 years without maintenance.

Modern turbines are typically rated  to run for 3 years without servicing,  

and there are no doubt some  which would run for decades,  

and one of them would probably have  at least a status LED in it somewhere.

Eventually, most of the wind turbines  would be stopped by the same thing that  

would destroy the geothermal plants:  Their gearboxes would seize up.

Generators that convert falling water  into electricity will also keep working.

An operator at the Hoover Dam once  said that if everyone walked out,  

the facility would continue to run  on autopilot for several years.

Though if the power grid is down, all  that electricity would have nowhere to  

go. In the end the dam would probably  succumb to clogged intakes or the same  

kind of mechanical failure that hit the  wind turbines and geothermal plants.

Battery-powered lights wouldn’t fare much  better, and will all be off in a few dozen years.

Even without anything using their power,  batteries eventually self-discharge.

Some types last longer than others, but  even batteries advertised as having long  

shelf lives typically only hold  their charge for a decade or two.

Solar power is probably the most promising  candidate. There are many off-grid solar-powered  

buildings, weather stations, and other remote  infrastructure around the world. Emergency call  

boxes, often found along the side of the road in  remote locations, are frequently solar-powered.

They usually have lights on them, which provide  illumination every night. Like wind turbines,  

they're hard to service, and  they last for a long time.

Solar panels will generally last as long  as the electronics connected to them,  

and as long as the panels are  kept free of dust and debris.

The wires and circuits will eventually succumb  to corrosion, but solar panels in a dry place,  

with well-built electronics, could easily  continue providing power for a century if  

they're kept free of dust by occasional  breezes or rain on the exposed panels.

If we follow a strict definition of  lighting, solar-powered lights in  

remote locations could conceivably be  the last surviving human light source.

But there's another contender, and  it's a weird one: spent nuclear fuel.

Contrary to popular portrayals,  radioactivity isn't usually visible,  

which is part of why we need warning signs  around areas with radioactive materials or waste.

Sure, watch dials used to be coated in  small amounts of radium to help them  

glow in the dark, but the glow didn't  come from the radioactivity itself.

It came from the phosphorescent paint on top of  the radium, which glows when it’s irradiated.

Once the phosphorescent paint breaks down,  

the watch dials are still  radioactive, but no longer glow. 

Watch dials, however, are not our  only radioactive light source.

When radioactive particles travel  through materials like water or glass,  

they can emit light through  a sort of optical sonic boom.

This light is called Cherenkov radiation,  and it's seen in the distinctive blue  

glow of nuclear reactor cores. Some of our  radioactive waste products, such as cesium-137,  

are melted and mixed with glass, which cools  into a solid block before being wrapped in  

more shielding for transport and storage. And in the dark, these glass blocks glow blue.

Cesium-137 has a half-life of 30 years,  which means that two centuries later,  

the blocks will still be glowing with  1% of their original radioactivity.

Since the color of the light depends only on  the particle decay energy, and not the amount  

of radiation, it will fade in brightness  over time but keep that same blue color.

And thus, we arrive at our  answer: Centuries from now,  

deep in concrete vaults, the light from  our most toxic waste will still be shining.