 We're here, half a mile under Mt. Ikenno in Japan, in a place that looks like a supervillain's dream lair. But we're not here hunting for Batman, we're searching for neutrinos, a neutral subatomic particle one and a half million times lighter than an electron, and 10 billion billion billion times lighter than a grain of sand. They were formed in the first second of the universe's creation, before even the first atoms were formed. Born from violent astrophysical events like exploding stars and gamma ray bursts, they're fantastically abundant in the universe and can move as easily through lead as we move through the air. But if they're so abundant throughout the universe, why are we in a bathtub deep underground trying to find them? Don't forget to subscribe so you never miss an upload and let's jump in. The neutrinos importance is not related to the headline-grabbing technical era from 2011, when it appeared that neutrinos were exceeding the speed of light, but rather because these particles are truly ubiquitous. Around 100 trillion pass through your body from the sun every second and give astronomers a unique ability to see into the otherwise impenetrable parts of the universe. Moreover, their properties challenge the standard model that's held together our basic understanding of physics for 50 years. The hunt for neutrinos began in 1930 when the Austrian physicist Wolfgang Pauli detected the existence of a neutral particle that was emitted during nuclear decay. During doing the math, Pauli discovered that when an electron was given off from radioactive decay, there was a small hole in the system's total mass-energy balance, and this was a very small hole. Keep in mind, a neutrino is a million and a half times lighter than an electron, so many would doubt these findings, chalking it up to a rounding error. But Pauli knew something was missing, and he predicted that it was an unknown, non-charged ghostly particle. Pauli struggled over his discovery of a particle he would have no way of detecting. Electrons and protons at a charge, making them easy to detect, and at the time, neutrons, which are comparatively massive, wouldn't even be discovered for a few more years. So how would you detect a charge-less, nearly massless particle? Funny enough, Pauli named his discovery a neutron, but when James Chadwick discovered the neutral version of a proton at an atom's center, he took the neutron name, and so Pauli's particle would be renamed a neutrino, literally meaning little neutral one. So why are we at the super-kamiokande neutrino detector here in Japan? This is where physicists are hoping to catch a glimpse of the elusive neutrino. Normally, this tank would be filled with water, so there aren't usually any people around. Lining the walls are thousands upon thousands of gold-hued detectors. These large bulbs are the key to observing an elusive neutrino. They're like light bulbs, but in reverse. Instead of making light, they capture it. In a regular light bulb, electricity goes in and light comes out, but with these detectors, light goes in and electricity comes out. The tank is fitted with 11,000 of these light bulbs, each a little larger than a human head. They're so sensitive that they could detect you lighting a match on your front long from the surface of the moon, and the tank that holds the super-kamiokande detector is enormous, as deep as the Statue of Liberty is tall. The tanks are water-trank-off detectors. The simplest detector is imaginable, filled with 50,000 tons of the purest water on earth. In fact, the water is so lacking in impurities, it's corrosive. Given long enough, it can dissolve metal. Something scientists discovered when they dropped a hammer in the tank. Years later, they found the hammer. The interior was hollow, and all that was left was a chrome shell. The water had eaten all the metal out of the hammer. Almost every neutrino that comes into the detector passes straight through with nothing happening. But every so often, about once every half hour, an extraordinarily unlucky neutrino will plow directly into a water molecule at just the right angle, disrupting and energizing it in such a way as to produce a flash of light. But it isn't these once every half hour neutrinos these scientists are interested in finding. They come from normal places, like our sun or extraterrestrial stars. They're looking for neutrinos born from supernovas, the explosions of a dying star. Despite normal neutrinos being commonplace, supernova neutrinos are much rarer and harder to detect. Even with this $140 million dollar piece of equipment, since 1983, scientists have only ever detected 25 supernova neutrinos, all from a single supernova, more than 30 years ago. When a supernova neutrino disrupts a water molecule in the tank, it racks in a manner distinct from neutrinos from other sources, allowing scientists to distinguish it. On top of that, a supernova is a neutrino bomb. When a sun's core implodes, it blasts its elemental riches throughout the universe and sends out trillions of neutrinos at nearly the speed of light. So catching one of these tiny neutrinos is like a cosmic window, and to our solar systems pass. Right now, the supercamioconde can only see supernovas that occur in and around our galaxy. But scientists expect they only happen in our corner of the Milky Way every 30 to 50 years. So it's a very patient waiting game for that elusive Eureka moment. But now, with a major upgrade, scientists are hoping to capture 5 every year by looking 35,000 times further into the vast multitude of space. By using gadolinium, an obscure element, the experiment could be much more sensitive. When a neutrino hits this pure water with gadolinium in it, it creates a gadolinium heartbeat, a small double flash of light, separated by about 30 millionths of a second. That double flash from supernova neutrinos is unique and distinctive, and allows you to wipe out the background noise so you get a clear view of the distant universe. This would allow us to see supernova neutrinos from up to a billion years in the past. Scientists hope that the supercamioconde with gadolinium will be up and running by the end of 2020. And by peering deeper into the universe, they hope to learn more about the supernovas that created the universe's heavy elements. Well, that's it for today on everything science. What do you think of the supercamioconde and the neutrinos it's hunting for? Be sure to let us know down in the comment section below. Have a great day, and remember, there's always more to learn.