Good things take time, and  science is no exception!

But come on, a 500-year-long experiment? Sometimes it really does take  decades, or even centuries, to make useful observations about the world.

After all, a human life is just a tiny  blip on the scale of the Universe. So let’s take a look at a few research projects that lasted way longer than  anyone could ever have expected. Here are six of the longest-running  experiments of all time. [Intro Music]

To kick things off, we have  the “Dark-Fly” experiment that was launched in 1954.

For more than 60 years, researchers raised fruit  flies completely in the dark. That’s about 1,500 generations of flies! A lot can happen across 1,500 generations, and these researchers were looking  for changes in the flies’ genome as they adapted to the dark environment.

Over the decades, they observed  several important changes. For one, when finally exposed  to a little bit of light, the dark-flies were better at  sensing it than the control group. Meaning their sight was not completely gone.

And, maybe it’s no surprise, the dark-flies were way  better at living in the dark than regular flies were. Specifically, they reproduced  far more successfully than their traditionally-reared cousins. Because after so many  generations of life in the dark, the dark-flies had developed  slightly longer head bristles, and a more sensitive sense of smell, enhancing their ability to live without sight.

Researchers identified dozens of  genes that differed from normal flies, and therefore might be the genetic adaptations that accumulated in response  to the dark conditions. The most recent dark-flies  experiment was published in 2020, but nothing else has been published since then. It seems that the dark-fly  strain might have ended; it does take a lot of time, effort, and research funding to maintain  special projects like this.

Luckily, their genome has been archived. Researchers can still mine their genetic code for insight to adaptations animals pick up when raised in the pitch black. Speaking of pitch, let's head over to the physics department to check out the pitch-drop  experiment that was set up in 1930.

Pitch can be derived from natural or manmade tar, and was traditionally used to  waterproof things like boats. It’s so viscous at room temperature  that it appears to be solid— you could even shatter it with a hammer! Yet it’s still a fluid, meaning it will flow.

But you better settle in, because watching pitch drip  is infinitely more boring than watching paint dry. In 1927, the first physics professor  at the University of Queensland heated up some pitch and poured it into a funnel. He waited three years for the  pitch to settle in the funnel, then he sliced off the tip and  waited for the pitch to drip out.

It took 8 years for the first  drop of pitch to detach! And in 95 years, it has  only dripped 9 times total. The funniest part is that all of those  drops happened without any observers, usually over the weekend or a holiday break.

In 1988, a physics professor was  eagerly awaiting the 7th drop. But he stepped out into the  hallway to get a drink of water, and when he returned, the  drop had already detached. In 2000, a video camera was  set up to record the 8th drop.

But a power outage at the fateful moment meant the 8th drop also went unobserved. Finally, the 9th drop was  captured on livestream in 2014. The watch for the 10th drop is ongoing, and you can tune into the livestream.

It’s been 11 years since the 9th drop fell, so you better head to the livestream  soon! It could fall any minute now! Centennial Bulb There’s another, even older  experiment equipped with a livestream: It’s called the Centennial Bulb,  and it was installed in 1901.

It’s been burning for 124 years, and although it wasn’t originally  designed as an experiment, scientists are keeping a close eye. Back when it was manufactured, practical light bulbs had only  been around for about 20 years. Thomas Edison patented the  incandescent light bulb in 1879, and the factory that produced the  Centennial Bulb was founded in 1896.

They made bulbs in the Edison style: hand-blown glass and a carbon filament, with the interior vacuum pumped to remove the air. The Centennial Bulb was actually part  of the last wave of incandescent bulbs made with carbon-based filaments. In 1904, tungsten took over  as the filament of choice, and was probably in the incandescent  bulbs that you grew up with.

Originally, the Centennial Bulb  glowed with a power of 60-watts, but over the decades its output  has dropped to about 4-watts. It was transported a few  times during its lifetime, and it was eventually moved to a dedicated  power source to ensure its stability. But besides those short windows without power, it’s continuously burned since  its installation in 1901.

It’s an unassuming bulb in a California firehouse, but it has captured international attention as the poster child of planned obsolescence. See, in the 1920s, light bulb  manufacturers got together and agreed to only produce bulbs  that burned out after 1000 hours. So all the major research on bulbs  went into limiting their lifespan, not extending it!

Several groups of scientists  have analyzed light bulbs from the same factory as the Centennial Bulb, trying to figure out what  makes them so long lasting compared to tungsten-filament bulbs, or even other Edison-style bulbs from the era. But they still aren’t quite sure what  makes the Centennial Bulb so special, and they’re afraid to unscrew it to find out. Once it reaches its natural death, perhaps an autopsy will reveal  its secret to longevity.

Before I tell you about an  even longer-running experiment, we gotta keep lights on a quick ad Thank you for watching SciShow! Every time you watch one of our videos, it helps them get out to even more people. Thank you for supporting  the channel with your time!

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Just go to complexlylearnathon.com  to check it out! Though the Centennial Bulb  became an experiment by accident, our next example was intended to be  a longterm project from the start. In 1879, Professor William James Beal buried a bunch of seeds with  decades of experimentation in mind.

He was curious how long seeds could  remain dormant before germinating. So he mixed 23 different seed types with sand, and buried them in glass bottles to  prevent water from infiltrating the seeds. After 5 years, he dug up the first bottle and  found that the seeds germinated when planted and watered.

And for the next 40 years, a bottle was unearthed in 5-year increments. After that, the interval was extended to 10 years. On the 100th anniversary of the experiment, the interval was extended to 20 years.

The most recent bottle was dug  up in 2021, and 4 bottles remain. Every single time, some of  the seeds have germinated! Without this systematic experiment, we wouldn’t know that seeds can remain  dormant for more than 140 years.

And this dormancy is crucial for seed banks. For example, the Svalbard Global  Seed Vault stores “back-up copies” of the genetic material encoded in seeds, useful in cases of disaster or  disease that wipe out entire crops. We still don’t know just how long seeds can remain dormant before  germinating successfully.

Even the remaining bottles  in the Beal Seed Experiment might not be buried long  enough to really find out. Seeds are nature’s way of storing  chemical energy for future use. But it wasn’t until the mid-1800s that  humans figured out how to do the same.

In 1840, someone created a  rudimentary chemical battery and hooked it up to a bell. This is the Oxford Electric Bell, or sometimes the Clarendon Dry Pile, because it’s housed in the Clarendon  Lab at the University of Oxford. No, Oxford doesn’t have a  case of collective tinnitus, this bell really has been ringing for 185 years.

A small metal ball oscillates between two bells, striking them twice per second. The candle-looking pillars in this  contraption are the power source. They’re called dry-piles, and they create  a charge difference between the two bells.

Each time the clapper ball touches a bell, it picks up a small charge that forces  it to swing back toward the other bell. Each of these cycles dissipates  a very tiny amount of charge, which explains why the dry-piles  still aren’t fully depleted! No one is quite sure what  the dry-piles are made from.

But they’re probably like  other dry-piles of the era, made from alternating layers of metal foil  and paper coated with manganese dioxide. These layers are sealed up with a sulfur coating. It’s an early version of a chemical battery, and might have been created  specifically as a demonstration that chemicals could hold electric charge.

The dry-piles create a voltage by  controlling the flow of electrons, and power this nearly 200-year-old bell. Since we can’t look inside the dry-piles, we don’t know how much longer  the bell will continue ringing. Just like the Centennial Bulb, we’ve just gotta wait for it to burn itself out.

But fun fact: the French word for a  non-rechargeable battery is still “une pile”! Honorable Mentions Before we get to our final long term experiment, I want to give rapid fire shout  outs to some honorable mentions. Starting with an experiment that’s tracked  more than 80,000 generations of E. coli.

The Long Term Evolution  Experiment only began in 1988, which is why it didn’t quite make this list. But 80,000 generations is eons to an E. coli! And since the E. coli have to be  transferred every 22-26 hours … that’s a lot of missed  vacations for the research team.

They freeze samples at 500 generation  intervals—that’s about every 75 days. The result is a hugely  comprehensive evolution experiment revealing insights to generational adaptation. There’s also been some super long  term surveys of human development, such as the Framingham Heart  Study that began in 1948.

For more than 75 years, doctors have  monitored a cohort of participants for signs of cardiovascular disease. At the beginning, everyone in  the study cohort were adults. But eventually the study expanded to  follow the original cohort’s offspring, starting when some of them were children.

Then some of the offspring’s children were also recruited to join the  study once they were adults. That’s three generations  of documented heart health! Geological regions are also  subjects of long term monitoring.

Scientists started monitoring glacier retreat  in the Juneau icefield starting in 1946. And the first volcano observatory  was established in 1841 to monitor seismological activity of Vesuvius. Lastly, I’d like to argue that  domestication and selective breeding are experiments that humans  have been running for millennia.

We’ve bred plants like teosinte and  brassicas into crops that are dependable, easy to grow and harvest, plus tasty to eat. Domesticated animals like sheep and goats  are quite distinct from their wild cousins, mouflon and ibex. These “experiments” all date  back about 10,000 years.

And it sure doesn’t seem like  we’ll give them up any time soon. 500 Year Experiment But let’s get to that grand finale: an  experiment designed to last 500 years. This one was initiated in 2014, and  it’s fully intended to last until 2514. Much like Beal’s seed experiment, the 500 year experiment will test  the viability of desiccated microbes.

The idea was inspired by a dried petri dish that one of the researchers  accidentally left in a box for 10 years. He rediscovered the dish and was  able to revive the dried up microbes, which got him wondering how long they  could survive in such a parched state. The researchers desiccated two types of  bacteria, and sealed them in glass vials.

For the first 24 years, one set of  vials will be opened every 2 years. After that, a set will be uncorked in 25  year increments… for the next 475 years. The experiment will conclude on June 30, 2514.

The timescale of this experiment  reveals just how little we actually know about the tenacity of life. Researchers hope they’ll learn how molecules like lipids, protein, and DNA degrade over time. The answers could have applications in astrobiology, drug storage, and space travel.

In 2018, the research team published  a follow-up to their initial paper. The results from the first few vials were ready. At that point, there didn’t seem to be  any significant decreases in viability.

Except a portion of the desiccated  microbes were exposed to space-like   vacuum or high concentrations of table salt. and those microbes didn’t end up doing so hot. No word about the other vials, yet. I’ll make a calendar alert to check in on  the experiment’s 50th birthday in 2064.

Science is beautiful because it  continually builds on previous knowledge to gradually expand our  understanding of the world. It’s only possible to learn  new things because our species has been systematically learning  for tens of thousands of years! In the grand scheme of the Universe, an individual human just doesn’t live that long.

So some experiments need to last much longer than any one of us will be around for. There are some things that only time can tell.