We've Detected Ghost Particles on Earth - What this means for science

Transcript: "(00:00) Keep watching to the end of  this video for a special Astrum  announcement 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 one that Galileo Galilei first used to   gaze up at the heavens and see the moons of  Jupiter. (00:24) 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 Arecibo telescope, that once  captured radio waves from across the cosmos.  What you probably aren't imagining, is a  cubic kilometre of ancient ice under the   surface of our planet’s South Pole. (00:55) 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 light  - but instead one of the most unusual and   elusive particles in the Universe. I’m Alex  McColgan, you’re watching Astrum, and today   we’re joining the IceCube Observatory in its hunt  for neutrinos - also known as ghost particles. (01:25) 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 Pole station - IceCube makes use   of the very ice in which it is built to  observe high energy neutrino particles. (01:48) 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. (02:13) 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. (02:44) 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. (03:10) 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. (03:36) And yet, over your entire lifetime,   there is only a 1 in 4 chance that even one  of those neutrinos will interact with an   atom that belongs to your body. Most of these  neutrinos are arriving 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  like supermassive black holes, or supernovae   or any other cosmic event with enough energy  to rip atoms into their subatomic particles. (03:45) 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 1 million years between bursting out  of the Sun’s centre to leaping off the surface   into space. (04:09) They are constantly absorbed and  emitted, 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,   travelling 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 IceCube is trying to observe. (04:56) Suspended down between one and a half and two  and a half kilometres in the darkness of the   ice shelf are 5,160 detectors arranged into a  lattice cube. Down here, the Sun’s rays have   been completely swallowed up by the thousands of  metres of compressed ice that lie above, and yet,   these detectors - called DOMS - are in fact light  detectors. (05:12) I already said that this telescope   is not observing light, at least, not direct  light reaching us from sources far out in the   universe. Neutrinos are so elusive, the DOMs must  detect them indirectly, by taking advantage of a   cascade of reactions that starts with a neutrino  colliding with an atom of frozen water, and ends   in a blue flash. (05:24) When the DOMs detect a blue  flash, the scientists know that either a cosmic   ray or a neutrino has passed through the ice,  and the hunt begins to find it’s cosmic origins.  The key step in this cascade, and therefore  the key to identifying a neutrino interaction,   is the muon particle that springs out of the  initial collision between neutrino and ice. 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. (05:43) 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 Cherenkov radiation. (06:20) Cherenkov 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 is in fact the quantum  equivalent of the sonic boom that roars out   from a supersonic jet plane flying overhead. (06:46) In this case, the plane moves through the air,   pressure or sound waves are pushed out in all  directions. With the jet’s 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. (07:10) The shock front then travels   out in a cone, trailing behind the aircraft,  which observers 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. (07:33) As the molecules  depolarise back to their usual state, they release   the energy that forced them into polarisation  as photons of blue light travelling 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. (07:58) If the muon was travelling slower than light  in the ice, there would be no wavefront,   and all the expanding light spheres would  destructively interfere with each other,  cancelling out to complete darkness. But since  the muon is travelling faster than light,   a shock front of constructive waves in the  form of blue light is created. (08:20) The thousands   of Digital Optical Modules of IceCube are  primed to detect this signature blue light   flashing through the ice. The miniscule time  differences between when one DOM registers the   flash and when the neighbouring DOMs detect it,  allows the scientists to triangulate the neutrino   and trace its path back through the ice, and  ultimately through the Universe to its origin. (08:44) These orb-like detectors are marvellous, intricate  devices designed to detect the faintest luminal   hints in the icy mass. Each DOM 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 (Botner et al., 2005). (09:07) 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 3-dimensional array, there is a lot   of data. (09:30) A whole terabyte of measurements are  captured every day, with a hundred 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.   IceCube detects around 275 million of them daily. (09:57) 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 IceCube 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 keyword here being ‘almost’ On the 22nd of September 2017, an exceptionally  bright burst of Cherenkov radiation was registered (10:41) by IceCube’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 centre of a distant galaxy,   hurling jets of particles towards Earth. This discovery was monumental. (11:14) It was   not the first time that IceCube 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. IceCube, and neutrinos,   had entered the world of multi-messenger  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 (11:51) 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. (12:15) IceCube 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.  IceCube is the noble watchmen, 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. (12:47) And even further than   that, IceCube 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 supernovae explosions  or cataclysmic mergers of unfathomably dense   neutron stars, or even the searing fury  of supermassive black holes. (13:12) IceCube 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; particles 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. (13:44) This allows physicists to test   their theories, and use the arrival of neutrinos  at IceCube to make new discoveries, not only about   the behaviour 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 extreme telescope as the IceCube Neutrino   Observatory: an effort that took seven years to  complete - with work pausing during the Antarctic   winter when planes are shutout from Earth’s  most southerly continent by the brutal weather,   only able to briefly resume for the summer months  of November to February. Over those seven years, (14:23) the IceCube team drilled 86 holes  two and a half kilometres deep,   using 18,000 litres of fuel per hole, and melting  750,000 litres of ice in the process. All to have   a few hundred scientist live and work in one of  the most inhospitable environments on our planet   in an attempt to understand the most extreme  events in our Universe, and to capture a glimpse   of the most elusive particle in the Universe. (14:58) 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. (15:25) Our solar system is filled with the Beautiful the  a inspire iring and the complex we love that so A   few years ago astram created something really cool  we made our very own book with highquality glossy   full page images of the planets in our solar  system packed with interesting details about   them to broaden your knowledge and instill  a sense of wonder not everyone got a chance   to get their hands on a copy Incredible  Universe the solar system sold out in   just a day but if you wish you'd been there  on that day 3 years ago you've not missed out (16:05) there will soon be another chance we're doing  another limited run of the Astron book it's a   great gift that can really spark the interest of  young teens and above in space and contain some   of my favorite images of our planets if you're  looking for something to get a loved one for   Christmas or just want a really great quality book  for yourself you have a chance to pre-order on   the astrom store until the 8th of September this  will be a limited run so once we ship in a month   that'll be that go check it out by scanning the  QR code or following the link in the description (16:38) below thanks for watching we are now very  close to our end goal of 1,000 astronauts   on patreon and I can't thank you enough  for having answered the call the closer   we get the more it's looking like I'll be  able to expand our content here and bring   back astram answers so submit your video  suggestions and questions over on patreon   if you'd like to become an astronaut you can  join the patreon with the link down below when   you join you'll be able to watch the whole  video ad free see your name in the credits (17:13) and submit questions to our team once again a  huge thank you from myself and the whole astrom team meanwhile click the link to this playlist  for more astrom content I'll see you next time

Key Takeaways

IceCube Observatory: Located under Antarctica’s ice, the IceCube Neutrino Observatory is a unique telescope designed to detect elusive neutrinos, also known as ghost particles.

Neutrinos:

Fundamental particles with no charge and almost no mass, making them extremely difficult to detect.

They interact with matter through the weak nuclear force, allowing them to pass through entire planets without interaction.

The majority of neutrinos detected by IceCube originate from the Sun, while some come from cosmic events like supernovae and black holes.

Cherenkov Radiation:

Occurs when particles like muons, created by neutrino collisions, travel faster than light in a medium (e.g., ice).

This radiation creates a blue light flash, which is detected by IceCube’s sensors, allowing scientists to trace the neutrino’s origin.

Importance of Neutrinos:

Neutrinos can reach Earth before light from astronomical events due to their ability to pass through obstacles like dust and magnetic fields.

They offer a unique perspective on cosmic phenomena, contributing to multi-messenger astronomy.

IceCube’s Role in Astronomy:

IceCube is part of a global network of observatories, alerting telescopes worldwide to significant cosmic events.

The observatory’s data enhances understanding of high-energy cosmic events and tests theories in physics.

Construction of IceCube:

The IceCube project took seven years to complete, involving drilling deep into Antarctic ice and deploying over 5,000 sensors.

Scientists endure harsh conditions to operate the observatory and collect data on neutrinos.

Astrum Announcement:

The video includes a promotional announcement for the re-release of the “Incredible Universe” book and a call for support on Patreon.

Hierarchical Bullet Points

IceCube Neutrino Observatory

Location: Antarctica, under the South Pole ice.

Purpose: Detecting neutrinos, elusive subatomic particles.

Detection Mechanism:

Relies on Cherenkov radiation caused by neutrino collisions.

5,160 detectors (DOMs) are used to capture blue light flashes from particle interactions.

Importance:

Offers insights into cosmic events, surpassing the capabilities of light-based telescopes.

Key player in multi-messenger astronomy.

Neutrinos

Characteristics:

Neutral charge, almost no mass.

Interact via weak nuclear force, not strong nuclear force.

Capable of passing through planets without interaction.

Origins:

Primarily from the Sun’s nuclear fusion.

Also from cosmic events like supernovae and black holes.

Detection Challenges:

Extremely difficult to detect due to weak interactions with matter.

Only interact with other particles on rare occasions.

Cherenkov Radiation

Definition: Blue light emitted when particles like muons exceed the speed of light in a medium (e.g., ice).

Role in Neutrino Detection:

Allows scientists to trace neutrino paths by detecting the radiation.

Helps identify cosmic sources of neutrinos.

Importance of Neutrinos in Astronomy

Neutrinos vs. Light:

Neutrinos arrive before light in some cosmic events.

Provide clearer data by avoiding interference from cosmic dust and magnetic fields.

Contributions:

Help study extreme cosmic phenomena.

Aid in understanding fundamental physics, dark matter, and particle behavior.

IceCube’s Contribution to Global Astronomy

Part of a Global Network:

Collaborates with other observatories to detect cosmic events.

Alerts telescopes worldwide to significant astronomical occurrences.

Data Output:

Collects massive amounts of data daily, mostly from cosmic rays.

Filters out rare neutrino events from this data for further study.

Construction and Operation of IceCube

Seven-Year Project:

Required drilling deep holes in Antarctic ice.

Involved challenging conditions and limited operational periods.

Scientific Commitment:

Researchers work in harsh environments to study neutrinos.

The observatory is a testament to human ingenuity in extreme scientific exploration.

Astrum’s Promotional Announcement

Re-release of “Incredible Universe” book.

Encouragement to support Astrum on Patreon for expanded content.

Conclusion

The overall theme of the transcript centers on the cutting-edge scientific endeavor represented by the IceCube Neutrino Observatory, which allows humanity to detect and study some of the most elusive particles in the universe: neutrinos. These ghostly particles provide a unique window into the cosmos, offering insights that are unattainable through traditional light-based telescopes. The IceCube Observatory’s groundbreaking work exemplifies the lengths to which scientists will go to expand our understanding of the universe, from enduring harsh Antarctic conditions to developing novel detection methods. This effort underscores the importance of neutrinos in broadening our comprehension of cosmic events and the fundamental forces that govern the universe.