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	2022-12-14: How Can Matter Be BOTH Liquid AND Gas? 19:09: Quasars or “active galactic nuclei” glow from the heat energy of matter being ripped to shreds as it spirals towards a supermassive black hole.
	2022-12-08: How Are Quasiparticles Different From Particles? 02:25: It has an effective positive charge due to the charge of the nucleus not being properly canceled by electrons in that location. 08:40: ... composite particles, for example an atom is composed of quarks forming a nucleus and electrons bound to that nucleus by the exchange of virtual ... 10:50: At the same time, the negatively charged electrons in a metal lattice attract the positive nuclei. 10:57: ... nuclei get tugged a tiny bit in the direction of a free-moving electron, and ... 11:12: The nuclei spring back again, and actually oscillate. 11:26: ... like, near absolute zero - then the phonons induced by the attraction of nuclei to a passing electron can be a dominant vibrational mode of the ...
	2022-11-23: How To See Black Holes By Catching Neutrinos 02:05: ... have even a 50-50 chance that the neutrino gets close enough to a lead nucleus to ... 03:38: ... high-energy neutrinos, interaction are with an atomic nucleus and that interaction can transmute the neutrino into its high-mass ... 08:53: M77 has what we call an active galactic nucleus. 09:05: ... disk is hidden from us by a wreath of dust and gas surrounding the nucleus. ... 14:33: There’s a tiny chance that a neutrino passing through the vitreous fluid of your eye will interact with a nucleus and produce Cherenkov radiation. 16:50: There’s a limit to how large a nucleus you can make this way - and that’s when the decay timescale is shorter than the rate of neutron bombardment. 16:58: ... of stability, you have to get through a region of extremely fast decay nuclei, and my guess is that known astrophysical processes can’t generate the ... 17:49: ... matter, and that this up-down-quark matter may lead to perfectly stable “nuclei” with atomic masses as low as ...
	2022-11-16: Are there Undiscovered Elements Beyond The Periodic Table? 00:38: ... of the periodic table are defined by the number of protons in the atomic nucleus - the atomic number - so how can there be gaps for new ... 01:38: ... electrons, which increase by one every time you add a proton to the nucleus, until the shell fills and you start over, filling the next shell ... 02:14: But there remained a missing element, right between Molybdenum and Ruthenium, which we figured out had to correspond to a nucleus with 43 protons. 04:04: For those, the instability sort of makes sense - their nuclei are enormous, so you might expect they’d have trouble holding themselves together. 04:29: For example, a carbon atom has 6 protons in the nucleus. 05:01: ... it in nature because it’s created when cosmic rays hit nitrogen nuclei in the ... 05:55: ... stability depends on the balance between protons and neutrons in the nucleus. ... 06:13: ... actually the dynamics of the atomic nucleus are so complicated that it takes sophisticated computer modeling to ... 06:34: An atomic nucleus is a place of extreme forces in delicate balance. 07:02: The story of how it binds entire nuclei is even more complicated. 07:21: If a nucleus gets too big, the strong force can’t keep things together and various types of nuclear decay become inevitable. 07:42: That means electromagnetism can overwhelm the strong force if protons are too close together, which is another way to destabilize the nucleus. 07:59: For smaller nuclei - up to an atomic number of 20 - an even split of protons and neutrons is usually the most stable. 08:31: To understand that we have to move beyond the common representation of the nucleus as a muddled blob of protons and neutrons. 09:18: The closer a nucleus is to those numbers, the more stable it will be. 09:37: ... means that even if we aren’t at a magic number of protons or neutrons, nuclei still prefer to have even numbers of protons, or even numbers of protons ... 11:01: There are so many factors at play that the only way to figure this out is to simulate the nucleus. 11:53: Patterns emerge, but not so as to give us clean rules for what is needed to yield a stable nucleus. 12:02: ... there is no configuration of neutrons that can stabilize that unhappy nucleus. ... 00:38: ... of the periodic table are defined by the number of protons in the atomic nucleus - the atomic number - so how can there be gaps for new ...
	2022-09-28: Why Is 1/137 One of the Greatest Unsolved Problems In Physics? 08:03: ... size of atoms - a larger  value means electrons would be closer to nuclei, making them more tightly bound and less  able to participate in ...
	2022-09-21: Science of the James Webb Telescope Explained! 12:36: Lassi Tiihonen and John Rizzo raise an excellent point: our strong force video didn’t really explain how atomic nuclei stick together. 12:52: We didn’t address how those protons and neutrons - those nucleons - then stick together to form multi-nucleon nuclei.
	2022-09-14: Could the Higgs Boson Lead Us to Dark Matter? 05:10: In the LHC we smash together particles of regular matter, like protons or heavier nuclei.
	2022-08-24: What Makes The Strong Force Strong? 00:04: It’s strange enough for atoms, but positively bizarre when we get to the atomic nucleus. 00:22: As you know, atoms consist of a nucleus of protons and neutrons surrounded by electrons. 00:53: The protons on the other hand are packed together in the nucleus as tightly as any matter in the universe. 01:05: So how does the nucleus stay together? 01:13: But if the strong force is so strong, why is it confined to the atomic nucleus? 05:12: We need this attraction to hold quarks together in nucleons, and nucleons together in the atomic nucleus. 05:19: And that attractive force needs to be stronger than the repulsive electromagnetism, while also vanishing outside the atomic nucleus. 06:20: So an electron bound to an atomic nucleus will feel less force from the nucleus at larger orbitals. 06:25: The further the electron gets from the nucleus, the more easily it can escape. 06:53: But this field looks very different to the electromagnetic field around a nucleus. 08:11: ... puzzle piece to explain why the strong force is never seen outside the nucleus. ... 09:05: You would have to get really close to an atom to feel the positive electric field of the nucleus, or the negative electric field of the electrons. 16:36: Today we’d doing comment responses for the last two episodes: there was the one on lattice QCD, where we talked about simulating the atomic nucleus. 01:05: So how does the nucleus stay together?
	2022-08-03: What Happens Inside a Proton? 00:00: ... probably start by learning to simulate even a   single atomic nucleus. But it’s taken  some of the most incredible ingenuity   ... 14:32: ... detailed simulations of entire collections of hadrons like the nucleus   of a single atom. We will never simulate  a whole universe this way ...
	2022-07-27: How Many States Of Matter Are There? 05:05: ... of composite particles: the electrons are elementary, but the atomic nuclei are little bundles of nucleons - protons and ...
	2022-06-22: Is Interstellar Travel Impossible? 12:22: Interstellar space is flooded with high energy particles, from simple protons to massive iron nuclei.
	2022-03-16: What If Charge is NOT Fundamental? 01:52: ... its similarity to the proton - they’re practically twins in the atomic nucleus, occurring with similar numbers and almost the same mass, with the only ... 03:29: ... example, with this choice of their relative isospins, it made sense why nuclei prefered to have roughly equal numbers of protons and neutrons, and at ... 01:52: ... its similarity to the proton - they’re practically twins in the atomic nucleus, occurring with similar numbers and almost the same mass, with the only major ...
	2021-11-17: Are Black Holes Actually Fuzzballs? 09:25: ... as the neutron star’s gravitational field is so intense that atomic nuclei are crushed into a soup of neutrons, a star collapsing into a fuzzball ...
	2021-10-13: New Results in Quantum Tunneling vs. The Speed of Light 00:32: It describes how quantum particles are able to move across seemingly impenetrable barriers - for example, when atomic nuclei decay. 02:03: For example, the protons and neutrons in an atomic nucleus are held in the potential barrier of the strong nuclear force. 02:22: In radioactive decay, particles that should never have enough energy to escape the nucleus are found to leak out. 02:41: We represent the location of, say, a proton in a nucleus as a wavefunction. 03:01: ... understand what happens when a proton bounces around inside a nucleus, we need to see how its wavefunction evolves according the the ... 03:13: This equation tells us that the wavefunction is mostly reflected or scattered back by the wall of the nucleus. 03:44: ... improbable isn’t impossible, and so if you then observe the nucleus, it’ll “collapse” into one of those two states - either business as ...
	2021-09-15: Neutron Stars: The Most Extreme Objects in the Universe 04:39: ... of its electrons. In fact it’s   a frozen plasma, in which its nuclei are locked together in a regular lattice. You might ... 05:48: ... reactions. Electrons start to   be driven into the iron nuclei in a process called electron capture. The negatively charged ... 06:38: ... we’ve gone down a few hundred meters, we see nuclei that can’t even exist outside   a neutron star. Where the star ... 07:06: ... we leave the outer crust for the inner crust, our nuclei become so neutron-rich that they start   to fall apart. We ... 07:43: ... the neutron drip intensifies, the  space between the nuclei fills with a   neutron gas. Meanwhile the electron gas ... 08:15: ... down the nuclei themselves  start to get fuzzy as protons are   ... 09:34: ... Nuclei reform radically, forming cylinders  containing many millions of ... 08:15: ... that it becomes hard to even localize  it to being inside a given nucleus.   By the time we reach the bottom of the crust, around a kilometer ...
	2021-08-03: How An Extreme New Star Could Change All Cosmology 06:51: ... are held in place by the coulomb force - electrostatic attraction to the nucleus. And those electrons can occupy discrete energy levels, where the higher ... 13:13: ... barely and that may change. Over millions of years, heavy isotopes - nuclei with more neutrons than protons, will slowly sink, or sediment, to the ...
	2021-07-21: How Magnetism Shapes The Universe 11:08: Electrons and atomic nuclei can be accelerated in this magnetic field to high energies - into what we call cosmic rays. 11:30: ... surrounded by a disk of gas, we have what is known as an active galactic nucleus - the most powerful of which are called ...
	2021-07-13: Where Are The Worlds In Many Worlds? 00:20: ... one branch of the splitting quantum multiverse a radioactive nucleus decay, in another it doesn’t; in one “world” a quantum event in your ...
	2021-06-09: Are We Running Out of Space Above Earth? 15:32: ... that they would never, ever merge - even if they got within an atomic nucleus width ...
	2021-03-23: Zeno's Paradox & The Quantum Zeno Effect 01:27: ... electrons moving between atomic energy levels, or the decay of atomic nuclei, can be frozen through the simple act of ... 07:47: ... - the same phenomenon that allows particles to “teleport” out of nuclei during nuclear ...
	2020-12-15: The Supernova At The End of Time 05:59: The star’s own electrons would be driven into its nuclei in a process called electron capture. 06:06: ... the star begins to collapse, which means more electrons driven into nuclei, and so in in a runaway ... 07:16: In a white dwarf, the nuclei can never recapture their electrons to become atoms again. 07:27: Meanwhile the nuclei stop interacting with the electrons and slow down as they cool. 08:02: ... black dwarf that our Sun will become, a single carbon or oxygen nucleus has been sitting neatly in its assigned column and row for many times ... 08:22: This quantum tunneling lands the nucleus close enough to its neighbor that the two fuse into a heavier element. 10:15: ... the last stage of the pycnonuclear fusion process, two silicon nuclei fuse to produce nickel, and then one of the nickel’s protons emits a ... 08:22: This quantum tunneling lands the nucleus close enough to its neighbor that the two fuse into a heavier element.
	2020-12-08: Why Do You Remember The Past But Not The Future? 06:23: First its heavier nuclei fall apart, and finally, maybe, its protons disintegrate.
	2020-11-04: Electroweak Theory and the Origin of the Fundamental Forces 01:24: It’s one of the main ways radioactive nuclei decay - the other being alpha decay, where the emitted “alpha particle” is really a helium-4 nucleus.
	2020-09-21: Could Life Evolve Inside Stars? 07:34: ... except to say that it might be catalyzed by interactions with atomic nuclei in the ... 07:42: Perhaps nuclei somehow help necklaces build a parallel chain of beads, that then peels off as an identical necklace, similar to how RNA reproduces.
	2020-09-01: How Do We Know What Stars Are Made Of? 04:42: As temperature drops, it becomes possible for some electrons to be captured by nuclei to form atoms.
	2020-08-17: How Stars Destroy Each Other 05:05: ... remnant core now contracts to the point that atomic nuclei are no longer distinct - instead they meld together, protons and ...
	2020-04-28: Space Time Livestream: Ask Matt Anything 00:00: ... far is my PhD thesis the host galaxies of radio loud active galactic nuclei I think it's only been read by the three examiner's my mother I don't ...
	2020-04-14: Was the Milky Way a Quasar? 01:19: But across the Universe, there are loads of “active” galaxies - ones that harbour active galactic nuclei, or AGNs, at their centers. 03:56: It goes like this: atomic nuclei - mostly lone protons - can get accelerated to extreme energies, typically in supernovae or other cataclysmic events. 04:06: These “cosmic rays” can then collide with nuclei in the gas between the stars - again, mostly the protons of hydrogen.
	2020-04-07: How We Know The Earth Is Ancient 07:17: ... age of chunks of the Earth through radiometric dating. Unstable atomic nuclei decay into lighter nuclei by splitting or by ejecting particles. The ...
	2020-01-27: Hacking the Nature of Reality 03:10: But problems returned when we started to peer into the atomic nucleus. 03:14: At the beginning of the 1960s the atom was understood as fuzzy, quantum electron orbits surrounding a nucleus of protons and neutrons. 03:40: ... were scattering experiments - particles were shot into atomic nuclei, and the internal structure was probed by the way those or other ... 04:10: ... understand a scattering experiment - like those used to probe the atomic nucleus - not by modeling all the cogs and wheels of the field theory of the ... 04:25: In this case the observables were the particles that entered and left the nucleus in a scattering experiment. 05:12: In standard use, the S-matrix can be calculated if you understand the forces in the interaction region - for example, in the nucleus of an atom. 05:43: ... 40s, but the approach came into its own 20 years later when the atomic nucleus refused to give up its ... 15:47: ... galactic nuclei come in many sizes - quasar is the name we use for the largest and most ... 16:10: And below the quasar range we have weaker active nuclei. 16:14: ... can be higher in the centers of small galaxies where those weaker active nuclei are ... 04:10: ... understand a scattering experiment - like those used to probe the atomic nucleus - not by modeling all the cogs and wheels of the field theory of the ... 05:43: ... 40s, but the approach came into its own 20 years later when the atomic nucleus refused to give up its ...
	2020-01-13: How To Capture Black Holes 04:08: ... these feeding supermassive black holes are called active galactic nuclei. ... 10:18: ... on the sky, which will typically contain hundreds of active galactic nuclei and many thousands of regular galaxies. Any of those could be the source ...
	2020-01-06: How To Detect a Neutrino 03:02: ♪ ♪ Those protons are then smashed into a graphite barrier, ♪ ♪ and as they collide with nuclei they produce all sorts of particles. 04:24: ... ♪ just long enough to exchange energy between the neutrino and, say the nucleus of an ... 04:37: ♪ ♪ just long enough to exchange energy between the neutrino and, say the nucleus of an atom. 05:26: ♪ ♪ In order for a neutrino to interact with an atomic nucleus ♪ ♪ it needs to pass so close that it's essentially inside the nucleus. 05:37: ... ♪ DR. DON: And if a neutrino interacts in our detector, ♪ ♪ an Argon nucleus is broken apart and charged particles are released - in particular, ...
	2019-11-11: Does Life Need a Multiverse to Exist? 04:56: He realized that with a tiny tweak of certain properties of the carbon nucleus, the universe would have hardly any carbon. 05:10: ... happy chance, the carbon-12 nucleus formed in this process has a natural internal energy state that allows ...
	2019-09-03: Is Earth's Magnetic Field Reversing? 05:32: In that motion I just described, electrons and nuclei should all be moving together – so no electrical current.
	2019-07-01: Thorium and the Future of Nuclear Energy 00:33: ... annihilation we have nuclear energy the strong nuclear force holding nuclei together contains an enormous amount of energy The Sun is powered that ... 02:49: ... Every fission reactor exploits the same phenomenon Certain very large nuclei like uranium and plutonium can split into smaller nuclei when hit by a ... 16:45: ... quasars the most luminous of accreting black holes or active galactic nuclei are Typically in bowl-like elliptical galaxies. So orientation isn't as ... 16:59: ... active galactic nuclei tend to live in spiral galaxies for example Seyfert galaxies and they ... 02:49: ... an atomic bomb But if you can regulate the process, make sure that each nucleus splitting causes on average only one other nucleus to break Then the reaction can ...
	2019-06-06: The Alchemy of Neutron Star Collisions 00:00: ... "We are star stuff", refers to a mind-blowing idea that most atomic nuclei in our bodies were created in the nuclear furnaces and explosive deaths ... 00:34: ... is blasted by a way of neutrons which get rammed into the escaping nuclei some of those captured neutrons convert back to protons and so elements ... 02:47: ... are composed almost entirely of neutrons a density similar to the atomic nucleus they also have a thin crust of iron densities are so high in fact that ... 00:34: ... on the periodic table is defined by the number of protons in the nucleus neutron number is variable and defines the isotope of the elements the r-process ...
	2019-05-16: The Cosmic Dark Ages 01:34: ... Bang. After 400,000 years of expansion things had cooled down enough for nuclei to recapture their electrons and the first atoms formed. The universe ...
	2019-03-06: The Impossibility of Perpetual Motion Machines 14:43: Recombination happened when the universe became cool enough nuclei capture electrons to form the first atoms.
	2019-02-20: Secrets of the Cosmic Microwave Background 02:05: ... matter, what we call baryons was in plasma form with the simple atomic nuclei stripped of their electrons in that extreme heat in this plasma state, ...
	2019-02-07: Sound Waves from the Beginning of Time 01:46: ... and the lightest of nuclei forged in the first minutes after the Big Bang, and still so hot that no ... 02:22: The electrons in turn exerted their electromagnetic pool on the nuclei. 05:11: At this temperature, electrons could finally be captured by nuclei and the first true atoms formed.
	2019-01-16: Our Antimatter, Mirrored, Time-Reversed Universe 00:42: ... episode the experiment that first proved this found that cobalt-60 nuclei decay by splitting an electron out in the opposite direction to their ... 01:48: ... an array of cobalt-60 atoms in a magnetic field, the cobalt nuclei have angular momenta that will align with a magnetic field let's say ... 03:02: ... vice-versa sending protons and neutrons to their anti versions in the nuclei of our now anti cobalt-60 and other anti-atoms sending matter to ... 00:42: ... decay by splitting an electron out in the opposite direction to their nucleus speed axis but in a mirror reflected universe the same decay should be in the ...
	2018-12-12: Quantum Physics in a Mirror Universe 00:02: ... should decay in the same way we tested this using the cobalt-60 atom the nucleus of this radioactive isotope of cobalt decays via the weak interaction ...
	2018-12-06: Did Life on Earth Come from Space? 00:37: ... space is thick with energetic cosmic rays near light speed atomic nuclei as well as x-rays and gamma rays endospores are somewhat resistant to ...
	2018-11-14: Supersymmetric Particle Found? 03:52: ... all expected to blast high energy particles like electrons and atomic nuclei into the ... 05:36: We detect neutrinos because very, very rarely one will interact with an atomic nucleus and produce a shower of particles.
	2018-08-01: How Close To The Sun Can Humanity Get? 04:51: ... the solar wind-- charged particles like electrons, protons, and heavier nuclei, measuring their energies and mapping them back to their origin in the ...
	2018-07-04: Will A New Neutrino Change The Standard Model? 01:22: ... by watching for the rare interaction between a neutrino and an atomic nucleus in some huge volume of matter, an entire glacier in the IceCube ... 07:21: Rare interactions with nuclei in the oil reveal the nature of the neutrinos.
	2018-04-25: Black Hole Swarms 04:15: Over the life of the Milky Way, they have piled up in the galactic core, forming a giant nucleus star cluster.
	2018-04-18: Using Stars to See Gravitational Waves 12:14: But it doesn't happen unless it is a solid nucleus for that first ice crystal to attach to.
	2018-02-21: The Death of the Sun 02:07: As the last traces of hydrogen are slammed together into helium 4 nuclei, fusion will cease. 09:57: ... of the energy bound into the system, whether the system be an atomic nucleus or a planet, and whatever that type of energy ... 10:31: The resulting combined nucleus is lighter than the sum of the masses of the two distant protons.
	2018-01-10: What Do Stars Sound Like? 12:39: In fact, the magnetic field of a gamma ray burst focuses charged particles-- electrons and the nuclei of the exploding star.
	2017-11-08: Zero-Point Energy Demystified 00:19: [MUSIC PLAYING] It seems pretty crazy that space itself might contain a higher density of energy than the nucleus of the atom.
	2017-10-25: The Missing Mass Mystery 06:25: On the other hand, if the material is cool enough, then nuclei can recapture their electrons and become a gas instead of a plasma.
	2017-10-19: The Nature of Nothing 07:50: Virtual particle-antiparticle pairs in the space between the orbitals and the nucleus align themselves with the electric field. 07:58: ... partially shields the orbiting electrons from the positive charge of the nucleus, with the amount of shielding being slightly different between these ... 13:53: But in a helium-4 nucleus, the protons pair up and have opposite spins, so they cancel out, same with the neutrons and the electrons. 07:50: Virtual particle-antiparticle pairs in the space between the orbitals and the nucleus align themselves with the electric field.
	2017-10-04: When Quasars Collide STJC 02:45: When gas from the surrounding galaxy falls into and feeds the central supermassive black hole, you get an active galactic nucleus-- AGN. 10:36: As such, we're renaming your personal Patreon contribution the Markarian 533 Binary Active Galactic Nucleus Fund. 02:45: When gas from the surrounding galaxy falls into and feeds the central supermassive black hole, you get an active galactic nucleus-- AGN. 10:36: As such, we're renaming your personal Patreon contribution the Markarian 533 Binary Active Galactic Nucleus Fund.
	2017-09-28: Are the Fundamental Constants Changing? 05:31: These same electrons are also orbiting the atomic nucleus, and that motion generates its own magnetic field.
	2017-09-20: The Future of Space Telescopes 12:18: That support gives way when pressure rams electrons into protons in the nuclei to turn them into neutrons. 12:33: During that collapse, the core looks more and more like a neutron star, basically a giant ball of neutrons with the density of an atomic nucleus.
	2017-09-13: Neutron Stars Collide in New LIGO Signal? 02:22: They are mostly composed of neutrons at the density of an atomic nucleus and are held up by a quantum mechanical force called degeneracy pressure. 08:43: Most heavy elements like gold, lead, uranium, et cetera, are produced when the nuclei of lighter elements capture fast-moving neutrons.
	2017-05-03: Are We Living in an Ancestor Simulation? ft. Neil deGrasse Tyson 13:19: Well, these particles are usually single atomic nuclei.
	2017-04-19: The Oh My God Particle 00:25: ... October 15th, 1991, a single atomic nucleus travelling at 99.99999999999999999999951% of the speed of light crashed ... 00:46: The nucleus quickly disintegrated into a shower of subatomic particles and lights. 01:21: That single atomic nucleus carried as much kinetic energy as a good sized stone thrown at your head at 50 miles an hour. 01:48: High energy particles, electrons, and small atomic nuclei, as well as gamma rays, are ejected when heavier radioactive elements decay. 03:31: Higher energy cosmic rays tend to obliterate themselves several kilometers above the ground in massive collisions with nuclei of air molecules. 04:51: ... air shower particles and detect the light produced as they smack into nuclei within the ... 05:06: Most of them are single protons, the nuclei of hydrogen atoms. 05:10: And a fair number are helium nuclei. 05:13: But about 1% of cosmic rays are heavier nuclei, as heavier as iron. 01:21: That single atomic nucleus carried as much kinetic energy as a good sized stone thrown at your head at 50 miles an hour. 00:25: ... October 15th, 1991, a single atomic nucleus travelling at 99.99999999999999999999951% of the speed of light crashed through our ...
	2017-01-25: Why Quasars are so Awesome 06:21: However, the family name for any type of accreting supermassive black hole is active galactic nucleus. 06:30: This is a simplified description of our modern understanding of quasars and active galactic nuclei. 08:20: ... some of this gas found its way into the nuclei of galaxies, it encountered there the supermassive black holes that had ... 09:13: Active galactic nuclei still do fire up in the modern universe, although usually they are at full quasar power.
	2016-11-30: Pilot Wave Theory and Quantum Realism 13:27: However, this doesn't work when there are only a small number of quarks, say in the typical atomic nucleus.
	2016-11-16: Strange Stars 05:10: Quark matter made of these quark types would need to be confined by incredible pressures to maintain stability outside the atomic nucleus. 05:58: ... universe, more stable even than iron, which is the most stable atomic nucleus. ...
	2016-09-07: Is There a Fifth Fundamental Force? + Quantum Eraser Answer 00:37: Atomic nuclei have energy levels, just like their electron shells do.
	2016-07-20: The Future of Gravitational Waves 05:41: ... so a package of two protons and two neutrons-- would tunnel out of the nucleus of a polonium-212 atom, causing the atom's radioactive ... 05:56: You had the half-life-- so the average time for the decay of a polonium-212 nucleus. 06:03: You needed to figure out how many times the alpha particle would encounter the walls of the nucleus in this time. 06:16: To do this, you needed to assume that the alpha particle bounces back and forth between the walls of the nucleus with a constant velocity. 06:23: ... combined with the size of the nucleus gives you the number of encounters with the wall and so the number of ... 06:32: ... kinetic energy, which I gave you, and you get the size of the polonium nucleus from the nucleus size relationship of the Fermi ... 07:03: ... this, you needed to calculate how far from the center of the nucleus, the Coulomb potential of the nuclear protons, reaches the 8.78 mega ... 07:23: Well, it started tunneling at the edge of the nucleus, around seven femtometers, and tunneled to 27. 06:32: ... which I gave you, and you get the size of the polonium nucleus from the nucleus size relationship of the Fermi ...
	2016-06-29: Nuclear Physics Challenge 00:37: For example, a particle bound within an atomic nucleus may spontaneously find itself outside the nucleus, where the binding force no longer holds it. 00:52: But don't literally take it, because it's one of the most radioactive elements known, and it decays as alpha particles tunnel out of its nucleus. 01:23: That's also the half life of an individual nucleus. 01:27: So after 0.3 micro-seconds, there's a 50% chance that a given polonium 212 nucleus will have decayed. 01:34: The challenge for today is for you to figure out the tunneling probability for an alpha particle to escape from a polonium 212 nucleus. 01:48: The walls of the box result from the strong nuclear force which holds the nucleus together. 02:27: ... wall bounces in 0.3 micro-seconds, you need the size of the polonium 212 nucleus, which you can calculate from the nuclear radius relationship, which ... 03:04: ... probability that an alpha particle will tunnel out of the polonium 212 nucleus on any one encounter with the edge of that ... 03:19: And the extra credit question-- how far does the alpha particle teleport from the nucleus when it pulls off this tunneling trick? 03:34: That happens when the potential energy of the cooling force trying to drive it away from the nucleus is equal to the kinetic energy of the particle.
	2016-06-01: Is Quantum Tunneling Faster than Light? 03:06: On its own, this would be a helium nucleus. 03:09: But these bundles also exist as parts of heavier atomic nuclei. 03:13: There an alpha particle is snugly bound into the nucleus by the strong nuclear force. 03:39: As an alpha particle approaches the force barrier of the nucleus, its wave packet is reflected backwards, usually. 04:10: There remains a tiny tail of probability outside the nucleus, beyond the reach of the strong nuclear force. 04:19: ... possibility space that looks like the particle teleporting out of the nucleus. ... 04:41: When it's an alpha particle escaping a nucleus, this is one of the most important mechanisms for radioactive decay. 04:52: Protons, neutrons, electrons, and alpha particles can quantum tunnel into nuclei in various types of fusion and particle capture phenomena. 05:01: In fact, without quantum tunneling, stars could not fuse hydrogen into heavy nuclei.
	2016-04-06: We Are Star Stuff 01:04: ... when those elementary particles start interacting to form nuclei, atoms, and molecules-- chemistry-- they result in levels of complexity ... 01:48: Every element on the periodic table is formed from nuclei of a defining number of protons. 01:54: Along with a similar number of neutrons, and beyond the nucleus, electrons swarm in their quantized shells. 02:51: ... vast majority of that hydrogen has a lonely proton nucleus, a trio of quarks that found each other about a millionth of a second ... 03:28: ... the electrostatic repulsion between them, fusing them into helium-4 nuclei. ... 04:08: ... fact, that helium-4 nucleus weighs less than the sum of the protons that went into it, and the ... 04:48: While the early universe had around 20 minutes to forge its nuclei, stars have millions to billions of years. 06:34: But iron is the most stable of all nuclei. 06:38: You gain energy by fusing nuclei into it, but you also gain energy by breaking up larger nuclei to get iron by fission. 08:15: ... explosion rips through those infalling shells, neutrons are rammed into nuclei, producing lead, gold, uranium, all of the heavier elements of the ... 01:54: Along with a similar number of neutrons, and beyond the nucleus, electrons swarm in their quantized shells. 04:08: ... fact, that helium-4 nucleus weighs less than the sum of the protons that went into it, and the difference ...
	2016-03-30: Pulsar Starquakes Make Fast Radio Bursts? + Challenge Winners! 03:18: At this time, the universe was full of plasma, atomic nuclei, and free electrons. 04:21: ... and helium nuclei, the other common charged particles hanging around the universe at this ...
	2016-03-09: Cosmic Microwave Background Challenge 02:42: ... with this plasma that consisted mostly of protons, electrons, and helium nuclei. ...
	2016-03-02: What’s Wrong With the Big Bang Theory? 02:49: ... force and the strong nuclear force-- that's the force that holds atomic nuclei together-- also become unified into one ...
	2016-02-03: Will Mars or Venus Kill You First? 04:43: The steady bombardment by high-speed atomic nuclei smashing through our bodies will certainly damaged cells and DNA.
	2016-01-13: When Time Breaks Down 01:33: Down to the atoms and nuclei, yes.
	2015-12-09: How to Build a Black Hole 01:33: ... element after another, in Russian doll shells of increasingly heavy nuclei that finally surround an ion ... 01:53: Fusing two ion nuclei absorbs energy. 02:03: Electrons are slammed into protons in the ion nuclei, forging a neutron star. 02:17: ... of a city, with a mass of at least 1.4 suns and the density of an atomic nucleus. ...
	2015-09-23: Does Dark Matter BREAK Physics? 07:14: ... unthinkably rare collisions between a dark matter particle and an atomic nucleus. ...
	2015-03-18: Can A Starfox Barrel Roll Work In Space? 07:41: ... maybe protons are unstable, and in quadrillions of years, individual nuclei will start falling ... 08:04: And that, if some of that matter appeared on Earth, it would trigger a chain reaction wherein every nucleus on Earth would revert into that state.
	2015-03-11: What Will Destroy Planet Earth? 05:54: ... everything in a universe is ripped apart by stretching space-- atoms, nuclei, individual protons, ...

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