Astrum Space - What We Detected in the Strangest Quantum Experiments on Earth

Episode Date: September 7, 2026

This Astrum compilation explores the strangest particle experiments on Earth. Discover the fusion technology recreating the physics inside a star, how we’re detecting cosmic ghost particles, and the strangest effects we’ve seen in quantum experiments, proving just how weird the physics of our universe can be. ▀▀▀▀▀▀A huge thanks to our Patreons who help make these videos possible. Sign-up here to support the channel: https://bit.ly/4aiJZNF To stay on top of space news, sign up to the Astrum newsletter: https://astrumspace.kit.com

You gotta try breakfast. And what better way than with a delicious pre-organic coffee? Starting with just $1 all day, every day now until December 31st. You gotta try breakfast. I'm participating in A&W locations in Ontario. New from Nespresso. Blend wellness into your coffee routine with a coffee plus range, infused with functional benefits. Choose the coffee you love with added B vitamins,

like coffee plus B12. to help support immune function, and coffee plus B6 to keep your day moving. Or go with the flow and choose ginseng delight. Our new double espresso with ginseng extract. Whatever lies ahead, don't change your morning. Let your morning change you. Discover coffee plus on espresso.com. Our sun is a colossal ball of hydrogen and helium 330,000 times the mass of earth.

But the sun doesn't just form the center of our solar system. Every second, thanks to the nuclear fusion reactions in its core, it generates a gargantuan, 386 trillion, trillion joules of energy, 175 quadrillion of which reaches the Earth in the form of sunlight. And it's this radiation that provides pretty much all the energy we use as humans on Earth. It underpins food chains, drives the weather systems we use for renewables, and of course, its sunlight captured by ancient plants, long buried in the earth's crust that we're still utilizing when we burn fossil fuels. But what if there was a different way to power our modern industrialized society?

What if, instead of relying on photons that have made their way through 150 million kilometers of space, We could create the nuclear fusion reactions that keep our sun burning to grant us an unending source of clean and efficient power. What if we could make a star on Earth? I'm Alex McCulligan and you're watching Astrum. Join me today as we delve into the heart of our star and find out if we truly ever could unleash its power on our planet. Humanity, it seems, has a power problem. Even as we burn through our dwindling fossil fuel reserves and climate chaos intensifies all around us, every year our energy requirements rise by an estimated 1 to 2%.

The need for a clean, efficient and inexhaustible energy source has never been so acute. For many decades, this has been the promise of nuclear fusion. Unlike nuclear fission, which splits rare and unstable isotopes to generate power, fusion technology aims to replicate the processes that happen inside our sun, fusing hydrogen into helium and releasing a huge amount of energy in the process. Yet, since fusion was first talked about as a serious contender for energy generation in the 1950s, it has become a cliché, that is, perpetually 30 years away from becoming reality. So why then does it seem that Fusion is always just out of reach?

And do the new private enterprises that have recently entered the field really offer any hope of shaking things up? To begin to answer these questions, there is no better place to start than the place that inspired fusion science in the first place, our sun. As strange as it sounds now, at the turn of the last century, we didn't know what powered the sun. The source of the heat and light that sustains all of life on Earth was a mystery. The leading theory was that the sun's energy came from gravitational contraction.

Simply put, the idea proposed that as a star gradually radiates energy to space, It cools and so collapses further under its own gravity, which in turn causes gravitational potential energy to be converted into heat in the star's core. Today, we know that is a genuine process. Not only is it involved in the formation of stars, it's also the reason that the gas giant Jupiter radiates more energy to space than it receives from the sun. In fact, the planet is shrinking by about two centimeters every year under its own gravity. And as the resultant internal heat works its way from deep in Jupiter's interior and out

into space, it drives the intense storms that dance across the planet's surface. But when it comes to powering a star, one scientist realized that contraction didn't stand up. In a 1920 paper, physicist Arthur Eddington wrote, If the contraction theory were proposed today as a novel hypothesis, I do not think it would stand the smallest chance of acceptance. He argued that contraction would be hopelessly inadequate for powering a body that radiates as much energy as our sun. Suspecting that stars were places in which hydrogen atoms were cobbled together into heavier elements, Eddington proposed a different source of energy, drawing on experiments carried out by fellow scientist Francis Aston.

Aston had shown that the mass of a helium nucleus was ever so slightly less than that of four hydrogen nuclei. So if a helium atom was just four hydrogens fused together, some mass was missing. Eddington believed that this missing mass was converted into energy by Einstein's E equals mc squared. And because C, the speed of light, is such a large number, the energy generated from even a tiny amount of mass is huge, meaning fusing hydrogen into helium would provide more than enough energy to power the Sun. Eddington's ideas were bold and unproven, but they soon inspired serious theoretical work, and in 1929, the first calculations of stellar nuclear fusion were published by Robert Descourt Atkinson and Fritz Haughtermans.

It turned out that the Sun and all stars were giant fusion reactors, taking the most common element in the universe, hydrogen, and fusing it into other elements, starting with helium. Now, replicating this process on Earth would be hugely advantageous, especially when compared to nuclear fission, the process that is used in nuclear power plants today. Where fission relies on splitting large and rare unstable isotopes such as uranium 235 and plutonium 239, stellar nuclear fusion, where relies on hydrogen, an element that is widely available on Earth through the electrolysis of seawater.

And unlike the radioactive byproducts of fission that create a huge disposal problem for modern nuclear power stations, the byproduct of stellar fusion is helium, an extremely useful element. Thanks to its exceptionally low boiling point, helium is used to cool the magnets in MRI machines. scientific research projects like CERN, as well as in the production of microchips. It's an essential element that we actually need more of. So how exactly do stars achieve this alchemy of fusing hydrogen into helium? And how a scientist going about trying to replicate the process? Well, the first thing to consider is the reaction medium.

The stuff stars are made of. Unlike matter on Earth, stars aren't even made of atoms and molecules, where negatively charged electron clouds orbit positively charged nuclei. Stars are so hot that electrons can escape atomic orbits entirely. The resulting soup of charged particles, ions and free electrons is known as plasma, and it's in plasma that nuclear fusion can take place. Now plasma is by far the most common material in the universe, making up well over 99.9% of visible, that is, non-dark matter.

But we are part of the 0.1%, that small amount of matter in the universe that's cool enough, that in general, electrons confined to orbitals and chemistry, not nuclear physics, dominates, allowing cool balls of rock covered in oceans of water like Earth to form. For us, creating such conditions, making plasma that's hot, hot enough to sustain fusion and containing it is a considerable challenge. You see, the Sun has one quite literal giant advantage on its side. It's so huge that the force of gravity holds the plasma in a near perfect sphere, with pressure at its core reaching 150 grams per centimeter cubed, so dense a teaspoon would weigh close

to a kilogram. The biggest fusion reactor on Earth, ITER in France, a leading international project that hopes to be operational in 2034, will use just a few grams of plasma material in a chamber of 830 cubic meters. Because it's under such low pressure, meaning particles aren't squeezed together like they are in the sun, this plasma has to be much, much hotter to achieve fusion, 150 million degrees Celsius, as opposed to 15 million degrees at the core of the sun. Now, fairly obviously, you can't just hold a material like this in a container made of normal

matter. If it contacted the sides, it would cool. Electrons would condense into atomic orbitals, and it would no longer be plasma. And of course, it goes without saying that the container itself would be damaged beyond repair. So the plasma needs to be isolated, isolated in a vacuum. Two approaches have been put forward to achieve this, the first of which is magnetic confinement fusion. Because plasma is a soup of charged particles, positively charged ions and negative electrons,

it can be manipulated by magnetic fields. Magnetic confinement takes advantage of this by using a ring of powerful magnets to hold plasma in a continuous donut-shaped blob in which fusion can take place. There are a number of different types, stellarators and reversed field pinch devices. But the leading design is called the Tokomac. This is the type of reactor which will be used at ITER. In contrast, inertial confinement fusion, the other confinement method, takes its inspiration from thermonuclear bombs.

It works by firing lasers or projectiles at a small pellet containing fusion fuel, seeking to create temporary blobs of plasma which release fusion energy only for a few nanoseconds before the plasma dissipates. Both of these approaches are immense engineering challenges, requiring either huge amounts of continuous electricity in the case of MCF, or even larger pulses of electricity drawn from banks of capacitors in the case of ICF. But not only do the huge amounts of power involved put tremendous strain on components, which have to be replaced frequently, it means that for a reactor to be viable, the energy obtained from the fusion reaction must exceed the colossal amount of energy required

to initiate it, a considerable challenge. As I was saying, fusion reactors take huge amounts of energy to get going. Now, you might think, surely, once you have surpassed this feat, you've got more energy out than you put in, that would be it. A huge win. After all, the fuel, hydrogen, is both cheap and abundant. But at last, it is not that simple. And to understand why we have to look back once again at our star and the fusion reactions that only take place deep inside the stellar core. And what better way than with a. whet organic coffee? Starting with just $1 all day, every day now until December 31st.

You gotta try breakfast at A&W. At participating A&W locations in Ontario. New from Nespresso. Blend wellness into your coffee routine with the coffee plus range infused with functional benefits. Choose the coffee you love with added B vitamins, like coffee plus B12 to help support immune function, and coffee plus B6 to keep your day moving.

Or go with the flow and choose ginseng delight. double espresso with ginseng extract. Whatever lies ahead, don't change your morning. Let your morning change you. Discover Coffee Plus on espresso.com. It is here in the sun's core that hydrogen is fused into helium via multi-step reaction. Firstly, two hydrogen nuclei or single protons combine with one undergoing a process called beta decay to transform it into a neutron. The resulting neutron proton proton pair is a nucleus of a heavy isotope of hydrogen known as Deuterium. In the next step, another proton combines with the Deuterium nucleus to generate a helium-3 nucleus.

In the final step, two of these helium-3 nuclei views to produce a helium-4 nucleus containing two protons and two neutrons, also known as an alpha particle, as well as two protons. Now, this may sound fairly straightforward, but it's not. The reason being that even in the sun, getting two protons to react to form Deuterium, the first step of the reaction, is far from easy. Firstly, in order to fuse, the protons must get extremely close to each other, around 10 to the power minus 15 meters apart. That is so, the strong nuclear force, the force that holds protons and neutrons together,

in the nucleus of an atom kicks in and they are drawn together. However, for two positively charged protons, getting this close means overcoming an immense amount of electrostatic repulsion, so much so that even the kinetic energy provided by the extreme conditions at the heart of the sun, where protons are traveling around 500 kilometers per second, is wildly insufficient. In fact, protons have only around one thousandth of the kinetic energy they require to overcome this barrier. It turns out the only reason the sun is able to sustain fusion at all is because quantum

effects come into play. Now, you may remember that according to quantum physics, protons don't just act as particles, they also act as waves. This wave behavior means that in 10 to the power 28 proton proteins, you know, that in 10 to the power proton interactions, the protons can overcome this energy barrier, getting close enough that the strong nuclear force pulls them together. This is called quantum tunneling. But even when protons are drawn together this way, there is yet another effect to contend

with. The force that mediates the conversion of one of the protons into a neutron is the weak force, which because it is controlled by the massive W boson, is a force. is very inefficient. This leads to the more likely product of the proton-proton reaction being a proton pair, which immediately decays back into single protons. Together, these effects mean that the rate of proton conversion in our star is extremely slow. On average, a proton will wait 10 billion years before undergoing fusion. Indeed, the only reason the proton-proton reaction proceeds at all is much more.

because there are a heck of a lot of protons in the sun, allowing it to convert 600 million tons of hydrogen to 596 tons of helium every second. This sounds like a lot, but it's actually only a tiny fraction of the hydrogen available for fusion. Now, stopping for a moment to look at the big picture, this is very good news for us Earthlings. It means, instead of annihilating itself in a giant thermonuclear explosion, the sun has been gently burning through its hydrogen stocks for around 4.6 billion years, and will continue to do so for at least a few billion more.

It's only because protons are so slow at converting into deuterium that we are here at all. For fusion on Earth, on the other hand, it is bad news. It means the probability of proton-proton reactions happening, where we have much less plasma and much less time, is essentially zero. Indeed, the reaction has never been experimentally measured. In fact, looking at the problem in the most basic and fundamental way, it is statistically impossible to achieve proton-proton fusion on Earth in any meaningful way.

So what are all these fusion researchers doing? Why do we even bother trying? Well, they are not attempting to fuse protons. Instead, they are trying to fuse alternative combinations of nuclei that are much more reactive. Back in the 1930s, Mark Oliphant, a student of Ernest Rutherford, conducted a series of experiments. He fired Deuterium nuclei at one another. generating other exotic hydrogen and helium isotopes, and thus proving that heavy hydrogen nuclei could be made to react with one another. Today, fusion scientists favor a combination

that was first put to use in the H-bomb, one that is 24 orders of magnitude more reactive than protons alone. It is Deuterium, remember this is classic heavy hydrogen, consisting of one proton and one neutron, and tritium. the even heavier isotope of hydrogen with one proton and two neutrons in its nucleus. The reason this combination is so much more reactive is that these extra neutrons lead to a greater strong force, and there is no need for one proton to undergo weak force mediated beta decay into a neutron. Now, deuterium and tritium aren't just more reactive than the protons that power the sun. They also give rise to different reaction products.

Instead of generating an alpha particle and two protons, they make an alpha particle and a neutron. But like the proton-proton reaction chain, they still produce a ton of energy. Energy that we can use to generate electricity. Just one gram of Deuterium-triteum fuel holds energy equivalent to 2,400 gallons of oil. So if we've identified more reactive starting material, we've identified more reactive starting material, materials that give us plenty of energy out, what's the problem now? Well, it's not one problem, but problems. Let's start with those neutrons.

Being lighter than alpha particles, they carry most of the energy of the fusion reaction and so have to be captured in order for their energy to be put to use. But controlling a subatomic particle with no charge is no mean feat. aren't affected by the powerful magnetic fields containing the plasma, and so stream out of the reactor in all directions at one-sixth the speed of light. To deal with this, most reactor designs utilize something called a blanket, a layer surrounding the reaction chamber as designed to absorb high-energy neutrons and heat up. This heat can then be used to generate steam, drive a turbine, and generate electricity.

But this approach is far from perfect. Neutrons aren't just absorbed by the blanket. They ping about everywhere, damaging everything they hit. This hugely limits the lifespan of many components, particularly the reactor walls. Another issue stems from the reactants themselves. While Deuterium is relatively common, being easily extracted from seawater, and cheap at $13 a gram, tritium is neither. It has a half-life of just 12.3 years, and the only commercial source are Canada's 19 Deuterium uranium nuclear reactors,

which produce just half a kilogram of tritium a year as a waste product. Now, ITER estimates that a commercial fusion plant would require around 125 kilograms of tritium a year to run. Current global tritium reserves are around 25 kilograms. and as half of Canada's reactors are due to be decommissioned this decade, this tiny reserve is quite literally going to decay away. But of course, scientists do have a solution up their sleeves for the tritium supply problem. As well as carrying energy out of the reactor, those high-energy neutrons produced by deuterium-tritium fusion

can be used for something called tritium breeding. The idea is that you make the blanket, surrounding the reactor out of a substance that generates tritium when bombarded by neutrons. The substance preferred by most fusion researchers is lithium, which upon absorbing a neutron helpfully decays into a helium atom and tritium. However, as ever in fusion, this solution comes with its own problem. If each Deuterium-triteum fusion reaction generates one neutron, which via lithium, can be used to generate one new tritium, you would need to operate at an impossible 100% efficiency

to prevent your tritium supply from dwindling. The answer most fusion researchers favor is to add layers of other elements like beryllium that can act as neutron multipliers, absorbing one neutron and spitting out too. But not only is beryllium toxic, it is also in short supply, and contaminated with uranium, which then bombarded with neutrons, leads to radioactive byproducts, less than ideal. And regardless, there are concerns that even with breeding, most reactors would struggle to generate enough tritium to be viable. So, at this point you might be thinking, hang on a minute. It seems a lot of the touted advantages of fusion, bountiful energy, plentiful starting materials, innocuous, if even useful byproducts, are kind of falling away.

Well, you'd be right. We're not fusing hydrogen, or at least the same isotopes of hydrogen that the star fuses, and we're not making just helium, but a bunch of other radioactive products as well. The simple truth, no matter what the headlines say, is that we can't make a star on Earth. and the shortcuts to create something approximating one, create a world of engineering challenges. This is why, since the first fusion reactor patent was granted in 1946, fusion has always seemed just out of reach.

Each solution comes with a new set of problems. But not all hope is lost. In recent years, things do seem to be changing with some hugely significant science breakthroughs, In December 2022, for the first time ever, more energy was obtained from a fusion reaction than was required to initiate it, a challenge that had eluded researchers for decades. At the National Ignition Facility, a research-scale ICF reactor in the US, 3.15 megajoules of energy was obtained from a tiny palette of DT fuel, using an energy input of 2.05 megastorferral.

Then in late 2023, the experimental jet reactor in the UK, a Tokomak, generated a world record 69 megajoules of energy from just 0.2 milligrams of DT fuel. And while international beer must like ITER inch closer to operation, a flurry of private investment has also entered the field, exploring alternative fusion technologies. One is the Massachusetts-based, Commonwealth Fusion Systems, backed by Google, Nvidia, and Bill Gates. It proposes using high-temperature superconducting magnets to produce a more compact Tokomac. CFS claims it will have a commercial plant online by the early 2030s. Another outfit based out of Washington State, Helion, believes it is going to get there even

earlier. Backed by the likes of Sam Altman, this company has taken a completely new approach to reactor design. It fires two rings of plasma together at a million kilometers per hour to generate fusion conditions, a sort of halfway house between magnetic and inertial confinement. This approach allows them to react Deuterium, not with tritium, but a reactive isotope of helium, Helium 3, doing away with the problematic tritium entirely. The use of Helium 3 is key to Helium's approach, because instead of producing an alpha particle and a neutron, these reactants generate an alpha particle and a proton.

Vitally, this means there is no neutral particle whizzing off out of the reactor carrying all the energy. Energy is retained within the plasma itself. As the reaction proceeds, the energy generates an increase in internal pressure and a change in magnetic field, which can be used to generate electricity directly. No Victorian steam turbines involved at all. What's the catch you might rightfully ask? Well, just like tritium, helium 3 is incredibly rare, and also has to be bred, this time

from Deuterium-Duterium reaction. And this process does generate those pesky reactor damaging neutrons. One of Helion's proposed solutions is to separate the two reactions, having commercial plants that will use Deuterium-3 and feeder reactors specifically for generating helium-3 that have planned shorter lifespans. But there is another issue with Deuterium Helium 3. This mixture requires much higher temperatures and fuel densities than conventional Deuterium Tritium fuel. Huge pulses of electricity are needed each time the reactor fires to generate fusion conditions, which puts immense strain on electricity supplies and reactor components. It's a considerable engineering hurdle

for Helium to overcome as the company embarks on building its first commercial scale. reactor, but CEO David Kurtly claims this plant will be online and supplying power to Microsoft data centers by 2028. Now, whether or not this comes to pass, only time will tell. However, even if none of these private ventures hit their well-publicized milestones, the fact that this investment exists at all reflects the moment the fusion sector finds itself in. With new algorithmic and AI tools now at their disposal, for many in the field, it does feel

like fusion is finally inching closer to reality. And though unsolved scientific and engineering problems exist, regardless of the approach used, the diversity of fusion technologies that now exist is a huge bonus. So while we'll never be able to recreate a star on Earth, it is very possible that the The one or even several of the approximations we are trying to build will play a pivotal role in the energy landscape of the future. I'll end by returning to Edington and his 1920 musings on the energy-powering stars. A star is drawing on some vast reservoir of energy by means unknown to us.

This reservoir can scarcely be other than the subatomic energy, which, it is known, exists abundantly in all matter. We sometimes dream that man will one day learn how to release it and use it for his service. The store is well night inexhaustible. If only, it can be tapped. Maybe finally, it won't be another 30 years until we find out if it can. And what better way than with a delicious Pratt organic coffee? Starting with just $1 all day, every day, now until December 31st.

You gotta try breakfast. I'm participating in A&W locations in Ontario. New from Nespresso. Blend wellness into your coffee routine with a coffee plus range, infused with functional benefits. Choose the coffee you love with added B vitamins, like coffee plus B12 to help support immune function, and coffee plus B6 to keep your day moving.

Or go with the flow and choose ginseng delight. Our new double espresso with ginseng extract. Whatever lies ahead, don't change your morning. Let your morning change you. Discover Coffee Plus on espresso.com. If I tell you to imagine a telescope, what do you see? Perhaps you picture an old wooden cylinder with lenses at both ends, similar to the one that Galileo Galilei first used to gaze up at the heavens and see the moons of Jupiter.

Or maybe your mind is constructing a cathedral-sized dome, with mirrors as big as tennis courts, like the telescopes high up in the mountains of Chile and Hawaii. Or you could even be drifting onto visions of enormous dishes, like the infamous Arcebo telescope that once captured radio waves from across the cosmos. What you probably aren't imagining is a cubic kilometer of ancient ice under the surface of our planet South Pole. And yet, deep below the frigid landscape of Antarctica,

There lies precisely this. A strange telescope in one of the most inhospitable environments on Earth, designed to observe, not visible light, but instead one of the most unusual and elusive particles in the universe. I'm Alex McColgan and you're watching Astrom, and today we're joining the Ice Cube Observatory in its hunt for neutrinos, also known as ghost particles. If you stood on this icy surface, you might not be aware that some of the rarest events in the universe are being observed beneath your feet. Located at the most southerly human-occupied base in the world, the Amundsen-Scott South

Paul station, Ice Cube makes use of the very ice in which it is built to observe high-energy neutrino particles. But why? Why this extreme environment and weird design? Because neutrinos are weird. Really weird. Neutrinos are fundamental particles like quarks and electrons. Most of these neutrinos arrive at Earth from the Sun, where they are released from the nuclear fusion reactions raging inside its core.

Other neutrinos will have come from more cataclysmic origins, such as a supermassive black hole, supernovae, or any other cosmic event with enough energy to rip atoms into their subatomic particles. Similar to electrons, neutrinos belong to the lepton family of particles, meaning that they do not interact with other matter through the strong nuclear force that binds other subatomic particles like protons and neutrons together. Unlike electrons, they are neutral and have almost no mass whatsoever. This lack of charge and tiny mass means that they can only interact with other particles

through the weak nuclear force, giving them their ghostly quality, and making them one of the most difficult particles for scientists to detect. So much so, that even when we do measure their presence, it is only through the impact they have on other particles. If that wasn't spooky enough, neutrinos can also pass through our entire planet, without acknowledging the existence of a single atom in the crust, mantle, core, or any other layer of the earth, flying straight out of the other side completely unnoticed. There are trillions of neutrinos surging through you every single second.

And yet, over your entire lifetime, there is only a one in four chance that even one of those neutrinos will interact with an atom that belongs to your body. Here we find further demonstration of the neutrino's complete refusal to engage with matter in the universe. Photons, created in those same nuclear reactions, may take one million years between bursting out of the sun's center to leaping off the surface into space. They are constantly absorbed and emitted in random directions over and over again by the atoms in our star, resulting in a long, meandering path to escape. Neutrinos instead zoom straight out of the sun in just two seconds, traveling at almost the speed of light itself.

As far as standard model particles go, neutrinos are certainly the more coy and antisocial of the group, but on occasion they do mingle with other matter, and in the process can create a drama of energetic particle events cascading out in their wake. It is this cascade, ice cube, is trying to observe. They might seem strange, but the 5,160 detectors, or doms, suspended down between 1.5 and 2.5 kilometres in the darkness of the ice shelf, are in fact light detectors. The sun's rays have of course been completely swallowed up by the thousands of metres of compressed ice that lie above, but that doesn't mean there is no light at all down here. Neutrinos and cosmic rays can penetrate into the ice, and when they collide with the atoms

of frozen water, they cause particles, like muons, to spring into existence. Muons are the key to identifying a neutrino interaction. As the newly created muon hurtles through the incredibly clear and dense ice, it can exceed the speed it takes light to move through that same ice. Now let's be clear, nothing can move faster than light. in a vacuum, but in other materials such as ice, liquid water and glass, light can be outpaced. This isn't a violation of physics, but rather a consequence of light slowing down more than other particles within the ice.

As the muon races beyond its photon counterparts, it generates a shockwave of blue light expanding in a cone-shaped pattern out from its path, an eerie phenomenon known as treasurer. Gerenkov radiation. Gerankov radiation is most commonly associated with nuclear reactors, eerily emanating through the water that surrounds their cores. This blue hue in nuclear cores, and strangely, also down in the ice of the South Pole, can look peaceful and atmospheric, but it is in fact the quantum equivalent of the sonic boom that roars out from a supersonic jet plane flying overhead.

In this case, the plane moves through the air, and pressure or sound waves are pushed out in all directions. With the jet speed building up towards the speed of sound, the waves in front start to bunch up, forming a shock front of high pressure. When the plane exceeds the speed of sound, it smashes through the shock front, causing a rapid change of air pressure. This is the sonic boom. The shock front then travels out in a cone, trailing behind the aircraft, which observes

will hear as a thunderous clap. In the case of the muon, the particle is not pushing air, but instead disturbing the electric fields of atoms in the ice with its electromagnetic charge, polarizing the water molecules. As the molecules depolarize back to their usual state, they released the energy that forced them into polarization as photons of blue light traveling out in all directions. This is happening all along the path the muon takes. through the ice. The travelling muon is triggering emission of electromagnetic waves from the water ice molecules,

which radiate out into all directions, producing a cone of emission in the direction of the muon's motion. If the muon was travelling slower than light in the ice, there would be no wayfront, and all the expanding light spheres would destructively interfere with each other, cancelling out to complete darkness. And since the muon is travelling faster than light, the shockfront of constructive waves in the form of blue light is created. The thousands of digital optical modules of ice cube are primed to detect this signature

blue light flashing through the ice. The minuscule differences between when one dom registers the flash and when the neighboring doms detect it, allow scientists to triangulate the neutrino and trace its path back through the ice and ultimately through the flash. the universe to its origin. These orb-like detectors are marvelous, intricate devices designed to detect the faintest luminal hints in the icy mass. Each dome is encased in a 13-inch spherical glass pressure case, which protects the electronics

inside from the extreme cold and high pressure of the Antarctic ice. Inside, there is a photomultiplier tube sensitive enough to detect even a single photon, along with various components that amplify the signal and convert it into digital data, which is then transmitted up the cables to the surface. And with so many detectors making up this three-dimensional array, there is a lot of data. A whole terabyte of measurements are captured every day, with hundreds of gigabytes of that being beamed by satellite to scientists across the planet for them to comb through in search of their ghostly quantum target.

Within this trove of data, lie the imprints of many particles arriving from beyond our atmosphere. The vast majority are cosmic rays. Ice cube detects around 275 million of them daily. Cosmic rays are interesting in their own right, but serve as an obscuring curtain of noise to those seeking neutrino interactions, which occur a million times less frequently, with only around 275 detected daily. But even with the 100,000 neutrino detections that Ice Cube makes each year, almost all of them are generated in our own atmosphere as debris from collisions of cosmic rays with atoms

in the gas that surrounds our planet, and not from cosmic origins themselves. The key word here being almost. On the 22nd of September 2017, an exceptionally bright burst of Schenkov radiates. was registered by Ice Cube's array of detectors. Working together, the doms used the tiny time differences between when they each detected the flash to trace the path of the muon and the exceptionally energetic neutrino that created it, all the way back to a powerful and mysterious cosmic source out in the depths of our universe.

A blazar, a supermassive black hole at the center of a distant galaxy, hurling jets of particles towards Earth. This discovery was monumental. It was not the first time that Ice Cube had detected neutrinos from deep, deep space, but this detection was the first to trigger a real-time alert to telescopes across the globe, indicating that there was something significant to look at in that direction. Ice Cube and neutrinos had entered the world of multi-messinger astronomy, where the cosmos is studied through not just light, like it has been for most of the history of astronomy,

but also gravitational waves, cosmic rays, and now neutrinos. Neutrinos are a particularly useful window for us to look through, because, like gravitational waves, they can arrive at us before the light from a major astronomical event does. Because of their ghostly nature that I talked about before, neutrinos take a very direct path to our detector, whereas light faces many obstacles like dust and magnetic fields that interfere with its journey and slow it down. Ice Cube is now fully integrated into a planetary network of observatories, constantly scouring the skies for signs of high energy events, ready to inform radio dishes, mirrors and lenses

precisely where to point to see rare and transient phenomena that we would otherwise miss completely. Ice Cube is the noble watchman, sounding the alarm to rally an army of telescopic troops across the globe, commanding them where to aim to catch sight of raging cosmic fires. And even further to that, Ice Cube can give us a unique view into the heart of these phenomena. Because again, unlike photons, neutrinos can escape relatively unscathed from high energy environments such as the core collapse of supernova explosions or cataclysmes. Ataclysmic mergers of unfathomably dense neutron stars, or even the searing fury of supermassive

black holes, Ice Cube can deliver new and different information. It can see things light-based telescopes are blind to, so to speak. The neutrinos it detects can hugely broaden our understanding of all these events, and of the most fundamental nature of the universe. During these events, physics is pushed to its limits. are accelerated to speeds and energies thousands of times greater than what we can achieve in our particle accelerators on Earth, like that of CERN. This allows physicists to test their theories, and use the arrival of neutrinos at Ice Cube

to make new discoveries, not only about the behavior and properties of neutrinos, but also about dark matter, and even about ice itself. This is why so much effort was put into building such an extremely extreme level. Team Telescope as the Ice Cube Neutrino Observatory, an effort that took seven years to complete, with work pausing during the Antarctic winter when planes are shut out from Earth's most subtly continent by the bruised weather, only able to briefly resume for the summer months of November to February. Over those seven years, the Ice Cube team drilled 86 holes 2.5 kilometers deep, using 18,000

liters of fuel per pole, and melting 750,000 liters of ice in the process. All to have a few hundred scientists live and work in one of the most inhospitable environments on our planet in attempt to understand the most extreme events in our universe, and to capture a glimpse of the most elusive particle in the universe. Neutrinos are the phantoms of the particle kingdom. It takes bold and ingenious ideas from ambitious scientists to witness even a single one neutrino. We know so little about them compared to other particles, but they are just as important in furthering our understanding of the fundamental laws of nature.

With each neutrino detected, we are moving closer to comprehending the universe and the powerful forces that shaped it. a delicious Pratt organic coffee starting with just $1 all day every day now until December 31st. You gotta try Pratt. At participating A&W locations in Ontario. New from Nespresso.

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Our new double espresso with ginseng extract. Whatever lies ahead, don't change your morning. Let your morning change you. Discover coffee plus on nespresso.com. Light is so much stranger than you might think. Sure, it may seem simple enough, traveling around the universe, delivering energy from one place to another.

It helps us see. It provides life to plants, and thus to our planet generally. It has a reputation for being very fast. And yet, for a source of energy that has become synonymous with greater understanding, light is surprisingly difficult to understand. Light helps us see other things better, sure. But when scientists tried to look at light itself, it was surprisingly difficult.

No, I don't mean that they started staring into any lamps. Please don't do that at home. but experiments in the last 200 years or so have proven that what light appears to be and what light is are actually two different things. For one simple reason, annoyingly enough, light behaves differently when you're not looking at it compared to when you are. What is the true nature of light? Why is it behaving strangely when we're not looking? And what does it say about how the universe really works. I'm Alex McColligan and you're watching Astrum, and in today's video, it's time we try and find out.

Let's shed some light on light. Let's begin with the basics. What is light? In the early 1700s, Isaac Newton theorized that light was made up of tiny little particles that he called corpuscles. But in 1801, nearly 100 years later, a man named Thomas Young discovered that, light must actually be more wave-like than particle-like. He proved this, using an important method known as the double slit experiment. He set up a source of light and shone it through

two narrow slits onto a board. Young noticed that rather than getting two bands of light on the other side of the slits, a strange striped pattern was forming. This was known as an interference pattern and was incontrovertible proof that light had been travelling, as a wave. Why? Let's talk about waves for a moment. When waves travel, they oscillate up and down. But when two waves try to oscillate the same point in space at the same time, you get something known as interference. Imagine you had a bathtub with a rubber duck sitting on the surface. Two waves reach the duck at once. One wave tries to raise the duck up, at the exact same time the other wave tries to drop it down.

What happens? Provided the waves are of the same magnitude and are perfectly out of phase, they will cancel each other out and the duck would not move at all. This is called destructive interference. Similarly, if the waves both try to raise the duck up at the same time, the duck would be raised twice as high. This is known as constructive interference. Because waves tend to expand in a circle, two waves next to each other, will start to both constructively and destructively interfere with each other. Here are two waves in water. See these lines?

These calmer patches are where the waves are cancelling each other out. This is the effect we see with light travelling through the two slits. As the light from one slit propagates, it cancels out the other wave of light at certain points, creating the interference pattern that Young noticed on the board. So the mystery was solved. Light was a wave and not a particle. Except there is more to this experiment than meets the eye. Let's fast forward another 100 years to 1905.

Scientists around this time had become puzzled by something known as the photoelectric effect. It turned out that when you shone a light on a metal surface, electron-like particles were coming off it. This was deduced to be because electrons in the metal were getting knocked off it by the increased energy the light was imparting. Imagine it like a fruit on a tree. If you pull the fruit off the tree, you need to use a certain amount of energy. Once the energy is greater than the strength of the fruit's connection to the branch,

the fruit pops off. This was happening with the light and the electrons. Once the light hit an electron and gave it enough energy to pass the threshold, it broke free from the metal. However, what surprise scientists, was that if you increased the intensity of the light, they had expected the electrons to be knocked away faster. If you pulled the fruit off the tree harder, it would come off faster. More energy equals more departing kinetic energy. However, this did not appear to be the case.

Instead, increasing the frequency of the light increased the velocity of the departing electrons. The intensity of the light didn't affect the departing electrons velocity at all, but did affect the quantity of electrons being emitted. It was a bit of a puzzler. Albert Einstein was the man who solved the puzzle. He deduced that light must be travelling in little packets of energy, so sending more of them, increasing the frequency was the only way to increase the energy going to the electrons. He called these packets photons and later earned a no one.

Nobel Prize for his work. Light, it seemed, was more like a particle again. Or both a wave and a particle at once? Of course, even this is not the full picture. To be honest, we aren't completely sure about the full picture even now. Instead, we have more results that are contradictory. Let's go back to the double slit experiment. Armed with the knowledge of photons, physicists once again took a look at the double slit experiment. Experimental techniques had improved in the last 100 years, and it was now possible to emit a single photon of light at a time. So the double slit experiment was done again. This time, only a single photon would be sent through the slit onto a detector on the far side. When this was done, the detector registered

the arrival of the photon at just a single point. So, light was behaving like a particle. again. But then, why had it interfered with itself in the previous version of the experiment? Scientists had an idea. They sent through multiple photons one at the time and plotted the result on the detector. And this is where the result became really strange. Once again, the detector started seeing the photons arriving at single points, one at the time, but bafflingly, the arriving photons started creating a pattern. It was the interference pattern. The proof that light behaved like a wave. But strangely enough, this was only occurring when a single photon was going through at a time.

Somehow, the single photon, which was leaving the detector like a particle and was arriving at its destination as a particle, was apparently in some way traveling through both slits at once, enough to then interfere with itself on the other side like a wave. If light was just a particle, then when it went through the slits, you wouldn't see this pattern. You would only see two blobs of light, one for particles that went through the slit and one for particles that went through the other one. And yet, here was the interference pattern with its multiple lines of light disproving that. Scientists tried to pin light down.

They set up the experiment, but this time with two more detectors at the slit so that scientists could observe whether it was indeed passing through both at the same time. It didn't. But at the same time, it stopped creating an interference pattern on the furthermost detector. And from this, scientists began to realize something. Light cared about being observed. To be clear, it didn't matter whether it was observed by a human eye or a machine. moment light was interacted with in some way by any particle, which is the only way we can

detect light, there's no other way to observe it, it started behaving differently than if it hadn't been detected at all. It was if light was snapping into focus any time the universe asked it the question of where exactly it was, when without the scrutiny it appeared to relax into something a little more nebulous. Bizarrely enough, this seems to imply that light actually is more like a wave of probability rather than any discrete particle or wave. Any time it was asked where it was, it confidently provided a definitive answer.

It was at this point on the detector. It was not at any other point. But with no one checking up on it, light seems to be travelling in all directions at once, in accordance with certain probabilities. If you ran the experiment multiple times, you could quantify. those probabilities, discovering that it was more likely to be on the bands of the interference pattern and less likely to be in the gaps. But any time a single photon of light was asked, it gave an answer that was 100% concrete.

This is highlighted through something known as the Three Polarizer Paradox. Consider for a moment a pair of polarizing sunglasses. Obviously, these reduce the amount of light that can pass through them, usually by about 50%, depending on the type of lens and the wavelength of light. They work by being formed of thin chains of molecules that run lengthways across the lens. Any light that oscillates in the same orientation as this lens gets absorbed. Any that is perpendicular to the chains can pass through without trouble. The interesting case occurs when a single photon is passed through an orientation that's diagonal to the lens. In this case, you don't get half a photon going

through. Apparently, you can't just absorb part of the oscillation that is parallel to the lines and let through the other part that is perpendicular. Instead, the photon snaps into either the one orientation or the other. It either is completely absorbed or passes through entirely, but now with a new perpendicular polarization to match what it would have to have been able to pass through easily. How do we know that the photon wasn't this orientation? all along, because of what happens when you start adding more lenses. When you place a second lens behind the first, you can block out the light entirely, provided the two polarizations are perpendicular to each other.

Let's say we rotate the second lens 90 degrees compared to the first one. Any light that gets through the first lens has a 0% chance of getting through the second, like trying to post a letter through a chain-linked fence. As a result, we see only black. But add a third lens and place it at a 45 degree angle between the other two, and bizarrely light starts making it through all three lenses again. This may seem counterintuitive. How does adding more blockages increase the amount of light that makes it through?

But this result actually rules out the possibility that the light has a fixed orientation. It must be snapping into focus at each new lens, rolling a quantum dice each time to see if it was the right orientation all along or not. If it makes it through the first lens, a 50% chance, it only did so because it was oriented perfectly perpendicular to the lens's polarization. Which means once it reaches the second, it's coming at it from a polarization that's diagonal. So once again, there's a 50-50 chance that it makes it through.

rolls a quantum dice again, and once again has a 50-50 chance of proceeding. If it gets through this hurdle too, then it again snaps to the new orientation, as if it were that new orientation all along, which it obviously wasn't. Which means that now it's polarized diagonally relative to the third lens, meaning that it now has a final 50% chance of getting through. Of course, some photons do not make it through all three of these probabilistic gauntlets, Only about 12.5% of them make it. But that's more than 0%, which is what was happening previously when you only had two lenses. Light likes to behave in discrete quantities.

It is quantum. It seemingly snaps to a discrete value when observed. And honestly, we don't really know why. If you think about a wave, there is no reason why you couldn't simply have half a wave. You could half it again and again an infinite number of times and still have an answer that makes mathematical sense. And yet, it seems that down on a low enough quantum scale, you can't half light past a certain point.

You can't have half a photon, or even one and a half photons. And if you try to do so, the photon instead snaps to one or the other nearest integer, based on probabilities. But only when it's asked. Otherwise, it's quite content to exist probabilistically, interfering with itself like a wave as it travels along, before jumping to an answer when later asked exactly where it is. What is going on here? This is still being theorized about.

The closest comparison we have to it is something known as harmonics, where on a bounded string only a certain number of waves can exist. a guitar string, you can have one wave or two or more, but never a number that isn't a whole number. It seems that light works in the same way. Perhaps something pinches the beginnings and the end of the path light travels down, although what this might be and what mechanisms drive it are unknown as of now. Fundamentally though, perhaps the craziest thing about all of this is that this isn't just about light. Although we focused on light behaving like a wave and behaving probabilistically, all particles of matter do the same.

Light is just another form of energy, and energy and matter are linked. Particles of matter, atoms, and even complex molecules, have been shown to have wavelengths. Electrons are just as quantifiable and just as driven by probabilities as photons are. We are apparently all driven by probability if you scale things down small enough. So what is everything truly made of? What makes up energy and matter that causes it to behave in the way it does? What is going on under the hood of reality? Why is the universe behaving different when looked at compared to when not?

And what does it imply to think that even you are on some level probabilistic? What this all means is anyone's guess. The person who figures it out will be the Einstein of our time. But for now, all we can say is that when it comes to reality, it seems the universe is playing dice. You and the world around you might be a lot less certain than you might have thought. You gotta try breakfast. You gotta try prayer you done. And what better way than with a delicious Pratt organic coffee?

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Our new double espresso with ginseng extract. Whatever lies ahead, don't change your morning. Let your morning change you. Discover Coffee Plus on Nespresso.com. Have a look around you. Everything you see from the skin of your hands to the screen you're watching this video on is a different combination of the same three building blocks of matter,

protons, neutrons, and electrons. Now, let's look a little farther, say at Mars, or the Andromeda Galaxy, or even halfway. across the observable universe, and still, there is matter made of protons, neutrons, and electrons, as far as the eye can see. At first, this might not sound all that surprising, but for once the mystery here isn't that we've seen something we can't explain, but rather that we haven't seen something we were expecting, a universe just as full of antimatter. I'm Alex McColgan and you're watching Astrum. Join me today as we explore the world of antimatter

and learn about its interactions with other particles and even with gravity. By the end of this video, you'll probably agree that antimatter is a bit weird, but you'll also see why some physicists are frustrated that it isn't weird enough. Let's get one thing out of the way first. Although it might sound like something straight out of science fiction, antimatter is very real. It forms a critical part of the standard model of particle physics, and particles of antimatter have been observed in experiments going back nearly a century. The very first detection of antimatter dates back to a 1932 experiment conducted by Carl D. Anderson at Caltech, using a cloud chamber immersed in a magnetic field.

When charged particles from outer space, broadly called cosmic rays, intercept the Earth's orbit and fly through this chamber, the magnetic field curves their paths according to the charge and mass of each particle, and the clouds show a visible imprint of their resulting trajectories. Anderson was hoping this experiment would help determine just what kinds of particles were streaming into the Earth from the cosmos, and he may have found just a little bit more than he bargained for. What Anderson saw was that these cosmic rays included both positively and negatively charged particles.

The masses of the negatively charged particles lined up exactly with the known mass of an electron, but some of the positively charged particles were far too light to be protons. Instead they appeared to have the mass of an electron despite having the opposite charge, And so these never-before-seen particles came to be known as anti-electrons, or later positrons for short. In 1936, Anderson would win the Nobel Prize in Physics for this discovery. Meanwhile, a British physicist, who was also destined to win a Nobel, had been developing a description of electrons that would fit nicely within the framework of quantum field theory.

His name was Paul Dirac. By 1928, Dirac had realized that in order to describe electrons as quantum fields in a way that was physically consistent with special relativity, they had to be part of a larger mathematical structure, later known as a Dirac spinner, that inevitably gave rise to both positively and negatively charged versions of the same particle. In this way, Dirac had predicted the existence of positrons before Anderson had even even built the cloud chamber that would detect them four years later. What's even more incredible is that electrons aren't the only fundamental particle to come

in a two-for-one Dirac spinner package. Other particles matter, like the quarks that make up protons and neutrons, each have their own anti-quark counterparts. These anti-quarks can come together to form antiprotons and anti-neutrons, which can then bond with positrons to form anti-atoms and antimolecules. You could make a whole planet out of antimatter, and from the outside, it would look quite similar to an ordinary planet made of ordinary matter. But if antimatter were too similar to matter, if the only difference were the sign of its

charge, then it would be impossible to explain why our universe contains so much of one and so little of the other. This cosmic mystery, known as the barionic asymmetry of the universe, sent physicists on a decades-long quest to try and find as many differences as they could between matter and antimatter. That quest lives on today, spearheaded by particle colliders at CERN that are capable of producing, trapping, and studying both positrons and antiprotons. But before we talk about these experiments, let's try to summarize what we already know about the properties of antimatter. When studying antiparticles in isolation, experiments have confirmed with ever greater

precision that their intrinsic properties, namely their masses, are exactly the same as for ordinary particles. And when studying how antiparticles are affected by electromagnetic forces, experiments have have again found that they behave the same exact way as ordinary particles, except with the opposite electric charge, just as Anderson had observed in his cloud chamber. But electromagnetism is just one of the four fundamental forces of nature, alongside gravity and the weak and strong nuclear forces. And as physicists began to better understand the weak force in the 1950s and 60s, they realized

that particles and antiparticles are actually affected by it quite differently. The first surprise was that ordinary particles could only feel the weak force if they were left-handed, and antiparticles could only feel it if they were right-handed. The concept of handedness or chirality is subtle and difficult to conceptualize for particles with mass, but a loose analogy can be drawn with the particle's helicity, which should be which describes whether a particle is spin-up or spin-down along its direction of motion. In this analogy, a spin-up particle is called right-handed, while a spin-down particle is called left-handed.

The second, and even crazier surprise, was that right-handed antiparticles experienced a different strength of the weak force, as compared to left-handed ordinary particles. In practice, this means that the quantum probabilities. for radioactive decay in ordinary nuclei are somewhat different from the probabilities of the analogous decay processes in antinuclei. This fundamental asymmetry between particles and antiparticles was first observed in a 1963 experiment run by James Cronin and Val Fitch of Princeton University, who would be awarded yet another Nobel Prize for their discovery. When this asymmetry was discovered, there was some hope that there was some hope that

it would explain the barionic asymmetry of the universe. Perhaps these differences in the weak force were responsible for the abundance of matter and utter lack of antimatter around us. But the maths didn't quite work out. There simply wasn't enough of a difference between the strength of the weak force acting on particles versus antiparticles. That was when physicists began to turn their attention to the strong nuclear force. Theoretical models, The models predicted that, just like in the weak interaction, there should be some differences in how left-handed particles and right-handed particles feel the strong force. But antimatter just keeps surprising us.

Every experiment to date suggests that the strong force treats particles and antiparticles just the same. This brings us to the last of the four fundamental forces and the subject of today's ongoing ongoing experiments at CERN, gravity. To be honest, suggesting that gravity might treat matter and antimatter differently is kind of a long shot. Think back to the popular legend of Galileo tossing stones of different sizes and materials from the Tower of Pisa. They all fell at the same rate because the gravitational acceleration on Earth is 9.8 meters per second squared, regardless of which object is falling. Of course, the experiment works even better in

vacuum chamber, where air resistance is taken out of the equation. Newton expanded on this idea and showed in the 17th century that your gravitational acceleration anywhere in space depends only on the mass of the object pulling you and your distance from it, but not on any of your personal properties, not even your own mass. This famous result, known as the equivalence principle is the foundation of Einstein's theory of general relativity, our most accurate and successful model of gravity to date. With that in mind, physics is still an experimental science at its core, and we can't know for sure whether matter and antimatter obey the same laws of gravity unless we check

for ourselves. The physicists at CERN set out to do just that, motivated not only by the barionic asymmetry of the universe, but also by a few speculative papers, suggesting that the cosmological properties of dark matter and dark energy could be more easily explained if antimatter were to have a negative gravitational charge, or, to put it simply, if antimatter were to fall up rather than down. There are several ongoing experiments at certain testing the gravitational properties of antimatter, including Aegis, G-bar and Alpha. Today we will focus specifically on a key experiment coming out of the Alpha Group

that was published in the journal Nature this past September. After decades of assumptions, this experiment has brought us real-world data on the gravitational acceleration of antimatter on Earth's surface. But before we show you the results, let's take a moment to appreciate just how intricately this experiment was designed in order to isolate and measure the effects of gravity. The first step in the experiment is to secure a beam of several million positrons per second emitted from a radioactive isotope of sodium. Most of these positrons end up colliding with ordinary matter in the experiment, causing miniature explosions in which positrons and electrons annihilate each other

and release a small burst of energy in the form of light. But a small fraction of the positrons survive as they are guided through the experimental apparatus, where they are cooled by low-pressure gases and trapped by electric and magnetic fields. But observing the effects of gravity on these positrons would be nearly impossible. Their masses are so small

that the tiny force of gravity felt by each particle is overshadowed by even the smallest fluctuations in the surrounding electromagnetic fields. That's why this collection of positrons is merged with a separate container of antiprotons, where they bond and form neutral anti-hydrogen atoms that are much less responsive to stray electromagnetic fields. And where did the antiprotons come from? Suffice it to say that they were produced by firing ordinary protons into a block of metal. Really, really fast. Yes, physics is awesome like that.

Once the anti-hydrogen atoms are created, they behave like tiny, weak magnets that can remain trapped by complicated arrangements of external magnetic fields. Now, this magnetic interaction is weak enough that it no longer overwhelms the gravitational effects that we are trying to measure. The chamber containing these anti-hydrogen atoms is nearly a vacuum. There are just about 200,000 atoms of ordinary gas per cubic centimeter,

compared to a typical atmospheric density of 20 quintillion atoms per cubic centimeter. Under these conditions, the trapped anti-hydrogen atoms almost never collide or annihilate with atoms of ordinary matter. Instead, they can more or less just float around the chamber for minutes or longer. But as the magnetic fields used to vertically trap the anti-hydrogen atoms are weakened, this random floating eventually allows the anti-hydrogen atoms to escape through either the top or the bottom of the chamber, where they can collide with a wall of apparatus, annihilate with some ordinary atoms, and release a small burst of light.

In the Alpha experiment, this happens over the course of about 20 seconds. The theory behind the experiment is that if gravity really pulls antimatter downwards, more of the anti-hydrogen atoms escape through the bottom than the top. The stronger the gravitational force, the more atoms escape through the bottom. The simulations the Alpha Team ran showed that under normal gravitational attraction, about 85% of the anti-hydrogen atoms should escape through the bottom, whereas only 20% of them would escape through the bottom if gravity pulled antimatter upwards. If there were no gravitational force at all, the simulation showed a more even distribution of 55% escape through the bottom,

probably only differing from 50% due to asymmetries in the experimental apparatus itself. What did the actual experiment find? Well, roughly 75% of atmospheric. anti-hydrogen atoms escaped through the bottom of the chamber, showing a clear preference for downward-pulling gravity. As any thorough scientists would, the Alpha team repeated this experiment to collect a variety of data points that could tell a more complete story. They redid the procedure under various levels of magnetic field bias, which applied external

upward or downward magnetic forces on the anti-hydrogen atoms. On this graph, a bias of minus 1G means that enough magnetic force is applied to counteract normal gravity, while a bias of plus 1G means that an extra G of magnetic force is applied to push the anti-hydrogen atoms downward and so on. The team made predictions through simulations for each bias, and for various possible gravitational interactions which produce the orange, green, and purple curves shown here. As you can see, the experimental data points shown in blue best match the orange curve, which represents the normal simulation, where gravity pulls antimatter downwards.

But because the data falls just a bit below this curve, the best fit gravitational acceleration was only 0.75G. Three quarters of the strength of gravity acting on ordinary matter. Does this mean that gravity affects matter and anti-perative? antimatter particles differently after all? Not necessarily. Let's have a look at the error bars. They indicate that there are two major forces of uncertainty in the results, including

an uncertainty in the applied bias, possible errors in alignment, and other systematic and statistical uncertainties. When accounting for these uncertainties, the best fit gravitational acceleration is actually reported as 0.75g plus or minus 0.13g plus or minus 1.6g. This means that a full 1g of gravitational acceleration is still fairly consistent with the collected data. Future experiments will be able to determine more precisely how strongly gravity acts on antimatter, but we can already rule out speculative theories that rely on antimatter falling up. instead of down.

In the end, despite how weird and backwards the world of antimatter is, it seems that only the weak force actually applies differently to particles and antiparticles, but explaining the barionic asymmetry of the universe would require much more drastic differences between the two, so scientists aren't done looking for them. Could there be new forces and particles that interact even more weak? weirdly with antimatter? Or would you be willing to accept that having so much more matter than antimatter around us is a mere coincidence? In any case, let us know if you've learned something new about antimatter from watching this video and whether this is a topic you'd

like to hear more on. I'm happy to announce we have a weekly newsletter to keep up with all the discoveries in our cosmos and our designer Peter has made the most beautiful email you'll ever receive. Sign up with the link down below. It's the best way to stay connected between videos, short, focused updates on what's new and fascinating in space each week. No spam, no filler, just the good stuff. You'll get the latest news, visuals, and insights delivered straight into your inbox.

If you enjoy Astrum videos, you'll love this. Join the newsletter and stay curious with us. Don't you wish you could just hit Skip on the worst parts of your life? You know the same way you can see. skip an ad? I get it. I'm Siaia and I live in Ice Cove. I've made some questionable decisions that didn't end up the way I planned and today I'm still figuring it out. Somehow things usually get worse before they get better. Apparently that's how I roll. So bundle up and come along for the bumpy ride. Stream a new episode of North of North Tuesdays on CBC Gem.