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2022-12-14: How Can Matter Be BOTH Liquid AND Gas?

  • 01:00: For example, it’s not just temperature that determines the state of matter, it's also pressure.
  • 01:29: The relationship between temperature, pressure, and phase is mapped on a phase diagram.
  • 01:43: And these also have boundaries, the crossing of which means changing state - say, by increasing temperature through solid to liquid to gas.
  • 02:02: For example, at low pressures there’s a boundary where increasing temperature takes you directly from solid to gas - we call that sublimation.
  • 02:11: ... can exist simultaneously, From the triple point, if we increase both temperature and pressure in the right proportions we follow the phase transition ...
  • 02:37: It's almost like the map gives out - as though our explorer experimentalists haven’t traveled that far across the realms of pressure and temperature.
  • 04:46: While pressure doesn’t influence liquid volume, temperature does.
  • 05:23: Increase temperature and the gas particles move faster, hit harder, again increasing the pressure.
  • 05:29: ... its behavior can be described by a simple relationship between pressure, temperature and volume given by the Ideal Gas Law: ...
  • 05:43: OK, that’s about enough blah pressure temperature blah blah.
  • 06:31: Now at room temperature it begins to sublimate directly into a gas.
  • 06:57: To reach supercriticality, we need to get to this part of the diagram, so both pressure and temperature need to increase.
  • 07:12: ... the temperature rises the pressure of the gas increases a proportional amount, but this ...
  • 07:54: We remain stuck following the transition boundary, upwards in temperature and pressure, trapped in our state by thermodynamics.
  • 09:46: When ice is applied to the chamber, temperature drops and CO2 liquid rapidly condenses from the supercritical phase.
  • 13:03: ... deep below ground in geothermally active areas can reach the high temperatures and pressures needed for a supercritical state, and even, albeit rarely, ...

2022-12-08: How Are Quasiparticles Different From Particles?

  • 09:49: But of course we have them pesky phonons, which at any significant temperature just add up to a lot of random jiggling of the atoms - AKA heat.
  • 10:22: Very low temperature means few random, noisy phonons.
  • 12:54: In fact at very low temperatures all of the pairs in an enormous network of flowing electrons can all occupy the lowest energy state.

2022-10-12: The REAL Possibility of Mapping Alien Planets!

  • 07:45: ... alloy that’s A) highly   reflective, B) has a high melting temperature because, as we’ll see, it actually gets very close   to the Sun, and C) ...
  • 18:29: ... liberated in the interaction effectively raises the temperature of that tiny patch of space, and   that can change the way the ...

2022-08-24: What Makes The Strong Force Strong?

  • 17:12: So the answer is yes, but the effect isn’t noticeable until a few billion kelvin in temperature.
  • 17:19: ... at that temperature forms a relativistic plasma, and we can produce such matter in our labs ...

2022-08-03: What Happens Inside a Proton?

  • 15:29: ... booba points out an error in our definition of “absolute zero” temperature. We said that   it is defined as zero kinetic energy in ...

2022-07-27: How Many States Of Matter Are There?

  • 02:02: Change in temperature results in change in state, or in a phase.
  • 02:06: ... shifts occur at temperatures specific to the material, for example ice melts into water when ...
  • 02:26: Transition temperatures depend on the material, but they also depend on pressure.
  • 02:32: For example, water boils and freezes at a lower temperature on a mountain top where the air pressure is low.
  • 02:38: Instead of a 1-dimensional relationship between phase and temperature, think of a 2-dimensional relationship with both temperature and pressure.
  • 02:59: ... example, at temperatures and pressures above the critical point, the line between gas and liquid ...
  • 03:12: The two numbers related on the phase diagram - temperature and pressure - are statistical properties of a large collection of particles.
  • 03:20: ... single water molecule doesn’t really have a temperature, it has a velocity - but the average energy of motion of all water ...
  • 03:37: For example in an ideal gas, pressure is proportional to temperature and inversely proportional to density.
  • 05:01: What happens if we increase the temperature of a plasma?
  • 05:21: Just as we tore apart the atom when we made our plasma, if we crank temperature up high enough we can destroy nucleons.
  • 05:36: This is the Hagedorn temperature, and when we reach it quarks are stripped from nucleons to produce a quark-gluon plasma.
  • 07:16: Here it's temperature versus baryonic potential instead of pressure, which is basically how much energy quarks can absorb or emit.
  • 08:32: In regular thermodynamics, the lowest energy corresponds to absolute zero temperature, which in turn means zero motion of particles.
  • 11:54: ... analogs of temperature, pressure, etc. are informational parameters like memory, computation, ...

2022-04-27: How the Higgs Mechanism Give Things Mass

  • 05:38: ... this example of a bunch of bar magnets.  These magnets have high temperature which makes   them move randomly, but as the system cools ...

2022-03-23: Where Is The Center of The Universe?

  • 15:19: That seems to have fallen out of favor, with geothermal vents and hot springs providing more promising temperature gradients and general chemistries.

2022-03-08: Is the Proxima System Our Best Hope For Another Earth?

  • 10:01: ... it may also be that the large temperature  differential drives powerful  atmospheric convection - planet-wide ...

2022-02-23: Are Cosmic Strings Cracks in the Universe?

  • 00:58: ... the final  phase transition. Keep heating until you hit   temperatures of the extremely early universe and a  phase transition occurs in ...

2021-12-29: How to Find ALIEN Dyson Spheres

  • 04:10: Dyson’s original notion was simply to search for points of light with temperatures of a few hundred Kelvin, but emitting the power of an entire star.
  • 04:21: Anything capable of producing that much power at that low a temperature must be huge - the size of a planetary orbit.
  • 04:58: Unfortunately, there are some obvious natural explanations for a planetary-orbit-sized object at a few hundred Kelvin temperature.
  • 06:47: If you know the mass of such a star, you can predict its size, its temperature, its brightness, its lifespan, and so on.
  • 07:20: Each would produce its own thermal spectrum at different temperatures.
  • 08:17: For something with a pure thermal spectrum, we can exactly identify its temperature from, say, the ratio of red light to blue light.
  • 08:31: For example, the higher the surface temperature of a star, the higher its total power output - it’s luminosity.
  • 08:38: If we graph temperature against luminosity we get something called a Hertzsprung-Russell diagram.
  • 08:44: For temperature we can just use color - because that’s easier to measure.
  • 09:25: So a star might appear too faint for its apparent temperature - dropping below the main sequence.
  • 09:40: The star would look cooler - lower temperature than suggested by its visible color alone.

2021-12-20: What Happens If A Black Hole Hits Earth?

  • 06:02: ... sizable fractions of the speed of light. This generates hilariously high temperatures - much hotter than the cores of a star. This is how we “see” black holes ...

2021-11-17: Are Black Holes Actually Fuzzballs?

  • 02:18: We can describe the behavior of the air in this room with very few numbers: its bulk motion, its temperature, pressure, etc.

2021-10-20: Will Constructor Theory REWRITE Physics?

  • 00:32: describe some aspect of the universe with numbers - like the temperature, pressure, etc of a gas or the position, velocity, etc. of a particle Step 2.

2021-10-13: New Results in Quantum Tunneling vs. The Speed of Light

  • 14:57: Any discontinuities that formed at high temperature can then be frozen into the field.

2021-08-03: How An Extreme New Star Could Change All Cosmology

  • 03:58: ... for every unit of surface area - but that’s just a function of its temperature, and you can measure temperature from the star’s ...
  • 04:37: ... Temperature is surprisingly easy to measure, but luminosity is less so. Luminosity ...
  • 05:39: ... with our measurements for temperature and brightness, we get a radius for Zee of 2140 kilometers, plus or ...

2021-07-07: Electrons DO NOT Spin

  • 13:59: ... compared to the maximum - if you opened the doors and  let the temperature ...

2021-06-23: How Quantum Entanglement Creates Entropy

  • 01:02: ... large numbers of particles. For example, a room full of air has a temperature,   which is a measure of the average energy of motion of all the ...
  • 12:35: ... properties - for example, thermodynamic properties   like temperature. We call these properties that are preserved through this diffusion ...

2021-05-25: What If (Tiny) Black Holes Are Everywhere?

  • 02:28: The distribution of particle energies should follow a blackbody spectrum, as though the black hole has a real temperature.

2021-05-11: How To Know If It's Aliens

  • 02:51: ... first nutrient injection. Hypochlorite should also be destroyed by high temperatures, explaining the non-detection in the control ...

2021-04-21: The NEW Warp Drive Possibilities

  • 10:19: Energy is distributed along these tracks, potentially as a plasma, in some places at some pretty insane temperatures.

2021-01-26: Is Dark Matter Made of Particles?

  • 04:48: It gives dark matter a temperature.

2020-12-22: Navigating with Quantum Entanglement

  • 09:49: ... systems of very few particles, perhaps in a vacuum or near absolute zero temperature. ...

2020-12-15: The Supernova At The End of Time

  • 07:35: ... all white dwarfs must cool to the temperature of the ambient space - now a frigid 3 Kelvin, but in the future even ...

2020-11-04: Electroweak Theory and the Origin of the Fundamental Forces

  • 10:03: ... high enough temperatures - above the Curie temperature - thermal energy causes the particles to ...
  • 11:48: ... at low temperatures, this symmetry is spontaneously broken - leaving an independent, massless ...
  • 12:02: By the way - by “low temperature” I mean anything below around 10^15 Kelvin.

2020-10-05: Venus May Have Life!

  • 00:00: ... places in our solar system Venus lands pretty low, with surface temperatures hot enough to melt lead and sulphuric acid ...
  • 01:33: This traps so much heat that the surface of Venus reaches a temperature hot enough to melt lead, and with a pressure that would crush most submarines.
  • 02:43: ... the surface is completely hellish, at around 50km altitude both the temperature and pressure are close to those at Earth’s surface, with the only ...
  • 08:11: ... entire lifecycle would have to remain in the regions with survivable temperature and pressure, and the critters need to somehow survive the crazy ...
  • 09:44: ... survive crazy conditions - including the vacuum of space and the extreme temperatures and pressures of meteor impact or atmospheric ...
  • 10:27: ... then carry spores into the temperature range once again where they act as nucleation centers for new droplets ...

2020-09-21: Could Life Evolve Inside Stars?

  • 03:16: But here, the quantum fields themselves changed state due to the rapidly dropping temperature.

2020-09-01: How Do We Know What Stars Are Made Of?

  • 03:26: The colour of a star depends on that temperature - blue for hot stars, red for cooler stars, and sort of greenish-yellow for stars like our Sun.
  • 04:42: As temperature drops, it becomes possible for some electrons to be captured by nuclei to form atoms.
  • 07:10: ... state you should get if you have a cloud of some element at a given temperature and ...
  • 07:27: Payne realized that it should be possible to translate a star’s absorption line pattern into measures of temperature and composition.
  • 07:38: ... as light deeper within the sun traverses a large distance, over which temperature and pressure drop ...
  • 09:56: She also developed a way to calculate the temperatures of stars just based on the absorption lines.

2020-08-17: How Stars Destroy Each Other

  • 01:17: At a critical point, that surface reached the temperature and pressure of a stellar core.
  • 04:02: ... hydrogen layer, sputtering and flaring as they do so, until a critical temperature and pressure sends them over the ...
  • 09:51: Eventually, the core of the white dwarf reaches a temperature of hundred of millions of Kelvin, and the star’s carbon and oxygen can begin to fuse.

2020-06-30: Dissolving an Event Horizon

  • 05:40: That’s because the more massive the black hole the lower the temperature of the radiation.

2020-06-22: Building Black Holes in a Lab

  • 09:19: ... or BECs, occur when gases are cooled to almost absolute 0. At these temperatures, quantum effects that are typically microscopic can become macroscopic. ...
  • 10:13: ... radiation. Here you can measure not just the existence, but also the temperature of the Hawking radiation. Taking the temperature of the evaporating ...

2020-06-15: What Happens After the Universe Ends?

  • 08:46: But that only works below a certain temperature - in the extreme temperatures of the Big Bang, the Higgs field could not grant mass.

2020-05-27: Does Gravity Require Extra Dimensions?

  • 10:08: The experiment is now typically done in a vacuum, with precise temperature control and electrostatic and magnetic shielding.

2020-04-07: How We Know The Earth Is Ancient

  • 01:48: ... as a ball of molten rock, which subsequently cooled down to its current temperature. Buffon spent six years measuring the cooling rates of materials in his ...

2020-03-16: How Do Quantum States Manifest In The Classical World?

  • 17:40: ... arrangements of air in the room lead to the same measurement of temperature and pressure - so we'll almost always observe those macroscopic ...

2019-12-17: Do Black Holes Create New Universes?

  • 06:18: ... a few degrees above absolute zero, rather than the typical 200-kelvin temperature of the typical interstellar ...

2019-09-03: Is Earth's Magnetic Field Reversing?

  • 04:18: It’s solid because of the pressure at that depth – at around 5500 Kelvin temperature, it would instantly melt at lower pressures.

2019-08-19: What Happened Before the Big Bang?

  • 06:09: These theories predict phase transitions in the behavior of fields as the temperature of the universe changes.
  • 07:01: ... a little ahead of others And that will lead to very small density and temperature fluctuations in the matter produced after ...
  • 07:25: In fact, this is perhaps the best evidence we have that inflation is plausible, it can predict the pattern of temperature fluctuations in the CMB.
  • 11:56: Enough to give the universe a temperature of 10 to the power of 27 or 28 Kelvin.

2019-08-06: What Caused the Big Bang?

  • 07:26: ... in flattened field has a high field strength due to the extreme temperatures of that time. As the universe cools the field loses strength and ...
  • 07:59: ... of the universe, rendering it, basically, empty and cools it to a low temperature. In fact, it super cools the inflaton ...
  • 08:16: ... field remains in a vacuum state that doesn't matches temperature - in the same way that water can become a supercooled liquid, much ...
  • 11:40: ... only way to get the sort of evenly distributed temperature we see in the Cosmic Microwave Background, is if lots of these bubbles ...

2019-07-18: Did Time Start at the Big Bang?

  • 04:38: ... just next to each other but literally in the same spot at which point temperature and density are ...
  • 08:52: ... the crazy densities and temperatures of the Big Bang singularity, and just after, GR comes into terrible ...

2019-07-15: The Quantum Internet

  • 13:26: ... in fact the system has much higher temperature tolerance even if the coolant escapes - natural air circulation should ...

2019-07-01: Thorium and the Future of Nuclear Energy

  • 02:49: ... metals or molten salts these can be liquid over a very large range of temperatures reducing the chance of accidental boiling and They allow the system to ...

2019-06-20: The Quasar from The Beginning of Time

  • 03:01: They keep the dome at the temperature of the upcoming night so that the giant structure doesn't warp and twist with the change in temperature.

2019-06-06: The Alchemy of Neutron Star Collisions

  • 13:02: ... still have been visible red orange everywhere reflecting the 3000 Kelvin temperature at that time although even by then most of the light was infrared the ...

2019-05-09: Why Quantum Computing Requires Quantum Cryptography

  • 14:09: ... that created the first map of Britain and the device that measures the temperature of the sea from ...

2019-03-28: Could the Universe End by Tearing Apart Every Atom?

  • 03:05: ... of the good ol equation PV Eagles NKT relating pressure volume temperature and the amount of stuff anyway the upshot is that positive energy ...

2019-03-13: Will You Travel to Space?

  • 14:18: ... the cog half of the device is at the same temperature or higher, It can be shown that it's just as likely to turn backwards as ...

2019-03-06: The Impossibility of Perpetual Motion Machines

  • 04:16: But ONLY if the chamber containing the cog is at a lower temperature.
  • 04:20: If it’s at the same temperature then the cog is as likely to be pushed back when the latch raises.
  • 04:39: With no energy or temperature gradient, no energy can be extracted.
  • 04:43: In fact there’s an absolute limit to the amount of energy that can be extracted based on a difference in temperature.
  • 05:01: ... maximum possible energy as heat flows between reservoirs of different temperature. ...
  • 05:30: ... principle a Carnot engine could extract energy from a temperature gradient and then pump it back in again, making it a candidate perpetual ...
  • 13:33: Francois Lacombe asks how astronomers distinguish the very small temperature differences in the CMB from the rest of the microwave noise.

2019-02-20: Secrets of the Cosmic Microwave Background

  • 01:24: Those blotches are tiny differences in temperature.
  • 01:28: deviations one part in 10,000 from the average temperature of only 2.7 kelvin.

2019-02-07: Sound Waves from the Beginning of Time

  • 05:01: At 380,000 years, the plasma hit a critical temperature of 3000 Kelvin, around the surface temperature of the coolest red dwarf stars.
  • 05:11: At this temperature, electrons could finally be captured by nuclei and the first true atoms formed.
  • 07:54: ... and the complex signature of that sloshing is imprinted in detail on the temperature map of the cosmic microwave background ...

2019-01-24: The Crisis in Cosmology

  • 07:34: The speckles are tiny differences in temperature,...

2018-12-06: Did Life on Earth Come from Space?

  • 00:37: ... similar forces apply when it smacks down at the other end of the journey temperatures in these rocks can rise to several hundred Kelvin in the impacts and ...

2018-09-05: The Black Hole Entropy Enigma

  • 04:03: ... properties of individual particles based on the global properties like temperature, volume, pressure, et ...
  • 09:04: He showed that black holes radiate random particles exactly as though they have a peak glow for a particular temperature that depends on their mass.
  • 09:13: So if black holes have a temperature, then they also have entropy.
  • 09:18: Good old-fashioned thermodynamic entropy tells us that change in entropy is change in internal thermal energy divided by temperature.
  • 09:26: ... Hawking just plugged his Hawking temperature into that equation along with black-hole mass for internal energy and ...

2018-08-15: Quantum Theory's Most Incredible Prediction

  • 14:23: Andrea Smith asks whether the Suns million Kelvin corona temperature is caused by magnetic reconnection.
  • 14:53: Just radiating it from the solar surface would lead to temperatures below 5800 Kelvin.

2018-08-01: How Close To The Sun Can Humanity Get?

  • 01:41: We still don't understand exactly why it burns at millions of Kelvin in temperature-- far hotter than the sun's surface below it.
  • 04:00: It will also measure the outward flow of the magnetic field through the pointing flux, as well as the plasma density and electron temperature.
  • 04:33: It'll make detailed measurements of their kinematic properties like velocity temperature and density.
  • 05:54: ... continuous exposure over many orbits to solar radiation and intense temperatures, upwards of 1,650 Kelvin, while keeping the instruments at room ...

2018-07-25: Reversing Entropy with Maxwell's Demon

  • 01:44: ... precisely, if we only know the thermodynamic properties of a system-- temperature, pressure, volume, et cetera-- how much extra information would we need ...
  • 05:25: The air throughout the box is the same temperature, so even if we open the door, temperature would stay the same.
  • 06:14: This temperature differential can then be used to drive a heat engine and do work.

2018-07-18: The Misunderstood Nature of Entropy

  • 02:02: For heat to flow, you need two reservoirs of different temperature.
  • 02:14: In principle, that work can then be converted back into heat and so the temperature differential can be reestablished.
  • 02:20: However, an inefficient engine will slowly deplete the difference in temperature, reducing the heat flow, and the engine winds down.
  • 02:44: Specifically, the change in entropy of each reservoir is the heat energy going into or out of that reservoir divided by its temperature.
  • 03:01: In fact, an increase in entropy means that the heat reservoirs are approaching the same temperature, reducing the capacity to do useful work.
  • 03:27: In reality, it will almost always increase unless energy comes in from the outside to reestablish the temperature differential.
  • 04:37: Macrostates are entirely defined by thermodynamic properties, temperature, pressure, volume, and number of particles.
  • 07:20: ... of thermal equilibrium, in which energy is maximally spread out and temperature, pressure, density, volume, et cetera have the values we expect from ...

2018-06-20: The Black Hole Information Paradox

  • 03:25: ... holes should radiate as though they have a temperature that is inversely proportional to their mass, and the mass of the black ...

2018-05-09: How Gaia Changed Astronomy Forever

  • 02:33: Now, combining those gives us the color of the star, which, in turn, gives us its surface temperature.
  • 02:38: The combination of stellar luminosity and surface temperature has incredible diagnostic power.

2018-05-02: The Star at the End of Time

  • 02:11: This rate will only increase as the core's temperature increases, and the Sun will burn through the hydrogen supply in its core in five billion years.
  • 02:21: ... the rate of fusion depends very sensitively on temperature, more massive stars with their hotter cores burn through their fuel much, ...
  • 04:43: If you increase the energy output but keep the size of the star the same, then you necessarily increase the surface temperature of the star.
  • 05:08: So increasing the surface temperature allows a red dwarf to shed all of those excess photons produced by its rising fusion rate.

2018-04-25: Black Hole Swarms

  • 05:09: That gas heats up to crazy temperatures.
  • 05:12: To us, it looks like a range of heat glows-- thermal radiation at different temperatures, with the hottest glowing with extremely energetic X-rays.
  • 06:54: ... only glow at a single extremely high temperature, while X-ray binaries glow at both high and low energies, due to the ...

2018-04-18: Using Stars to See Gravitational Waves

  • 12:09: For example, it's energetically favorable for liquid water to freeze below a certain temperature.

2018-04-11: The Physics of Life (ft. It's Okay to be Smart & PBS Eons!)

  • 00:56: A hot cup of coffee will tend towards the same temperature as the room, and the hot, dense of our universe must expand.
  • 06:29: ... energy flows from hot to cold, seeking a uniform temperature, but energy is also dispersed into every form it can take consistent with ...

2018-04-04: The Unruh Effect

  • 06:36: The vacuum should appear warm with a temperature proportional to the acceleration.
  • 09:38: You need to accelerate at a rate of 10 to the power of 20 meters per second squared to increase the temperature via a single degree Kelvin.

2018-03-21: Scientists Have Detected the First Stars

  • 01:57: We say that the electron spin temperature was coupled to the CMB temperature.
  • 02:20: ... light from those stars shifted the equilibrium so that the electron spin temperature became connected to the temperature of the gas, instead of the ...
  • 04:56: We know exactly it's temperature at the moment of the creation of the CMB so there's a limit to how much it could have cooled since then.

2018-03-15: Hawking Radiation

  • 07:47: Black holes should have a heat glow with an apparent temperature that depends on their mass.

2018-02-21: The Death of the Sun

  • 02:14: That helium is useless as a fuel, at least for now, because helium fusion requires temperatures of around 100 million Kelvin.
  • 04:31: It heats up to that critical 100 million Kelvin temperature, then in an instant, it ignites in the helium flash.

2018-01-31: Kronos: Devourer Of Worlds

  • 04:16: And elements with high condensation temperatures, like silicon and most actual metals, were in extreme over-abundance in Kronos.
  • 04:24: Low condensation temperature elements, so-called volatiles, like carbon, nitrogen, or oxygen, were only slightly more abundant.
  • 05:32: Terrestrial, or rocky, planets are made of elements with high condensation temperatures.
  • 05:45: ... they condense at core temperatures, they remain vaporized in the inner solar system, but come together ...

2018-01-24: The End of the Habitable Zone

  • 01:22: The rate of fusion of hydrogen into helium increases with the temperature and density of the core.
  • 02:06: ... increases the density and temperature of the core which increases fusion rate, once again re-establishing ...
  • 03:41: Normally we associate higher temperatures with increased CO2.
  • 04:01: However, over hundreds of millions of years, CO2 will actually be lost due to rising temperature.
  • 04:08: See, the rate of weathering of silicate rocks increases with temperature and that process sucks in CO2 to produce carbonate minerals.
  • 04:40: ... will hold out for a bit but not for long with the ever increasing temperatures dropping CO2 and the evaporating ...
  • 05:48: But planet surface temperature and the location of the habitable zone depends on the planet's atmosphere as well as the star's brighteners.
  • 08:14: ... will last a while longer being much more able to adapt as surface temperature approaches the boiling point of water and atmospheric CO2 ...

2018-01-17: Horizon Radiation

  • 11:20: The vacuum acquires a non-zero temperature.

2018-01-10: What Do Stars Sound Like?

  • 00:49: ... equilibrium allow us to calculate things like the density and temperature of the core, the way energy flows to the surface, and even the life span ...
  • 05:43: Which in turn depends on the stratification of temperature, density, and composition.

2017-11-22: Suicide Space Robots

  • 01:48: ... first ever transmission from the surface of another planet-- accurate temperature and pressure readings of the atmosphere that killed ...

2017-11-02: The Vacuum Catastrophe

  • 10:28: Temperature is just a measure of the average kinetic energy per particle, so a little bit of energy leads to very high temperatures.

2017-10-25: The Missing Mass Mystery

  • 06:57: It seems that the missing material must be in the intermediate temperature range.

2017-10-19: The Nature of Nothing

  • 00:57: We saw that it's actually impossible to reduce any substance to absolute zero in temperature.
  • 11:57: Last week, we talked about the wonders and the impossibility of absolute zero temperature.
  • 12:56: The point at which a substance changes phase depends on both temperature and pressure.
  • 13:02: The higher the pressure, the higher the temperature of these phase changes.
  • 13:06: ... and Saturn may be largely liquid hydrogen, despite the fact that the temperatures there are way higher than the atmospheric pressure evaporation point of ...
  • 14:10: Flo Striker was wondering about the idea of negative kelvin temperatures.
  • 14:17: It's not very intuitive, though, because having a negative temperature means the substance is hotter than any substance with a positive temperature.
  • 14:26: ... normal positive temperatures, particle kinetic energies span a large range, but always have a ...
  • 14:38: But at negative temperatures, most particles are excited towards the highest possible energy states.
  • 14:52: So why call them negative temperature?
  • 14:57: Temperature can be defined as the rate of change of thermal energy divided by the rate of change of entropy.
  • 15:29: So if temperature is change in thermal energy over entropy, then temperature is negative.

2017-10-11: Absolute Cold

  • 00:28: Temperature is just a measure of internal kinetic energy.
  • 00:37: But what if we reduce temperatures so much that all particle motion ceases?
  • 00:42: This state of absolute cold is the zero point in the Kelvin temperature scale corresponding to negative 273.15 Celsius.
  • 01:52: Temperature just represents the average kinetic energy of the countless particles.
  • 01:57: And while a substance can theoretically have any temperature above absolute zero, its component particles cannot.
  • 03:29: ... entire substance can somehow remain a fluid when it reaches the critical temperature for Bose-Einstein condensation, it becomes what we call a ...
  • 04:20: It remains a liquid down to the smallest possible temperature.
  • 04:40: In theory, absolute zero temperature means no thermal energy so no internal motion of particles whatsoever.
  • 05:38: At the lowest temperatures, particle motion acquires a sort of quantum buzz.
  • 05:44: This translates to a very real minimum in average energy and to a minimum temperature.
  • 05:50: That temperature is just a teensy bit higher than absolute zero.
  • 06:07: There's always a little bit of kinetic energy remaining, and so it's impossible to reach absolute zero in temperature.

2017-09-20: The Future of Space Telescopes

  • 01:27: ... in addition, because rock solidifies at a much higher temperature than volatiles, like ammonia and water, terrestrial planets tend to form ...

2017-08-24: First Detection of Life

  • 05:46: It takes a lot of energy to cause it to change temperature.
  • 05:49: ... means it can exist as a liquid over a large temperature range and grant's temperature stability for the delicate organisms ...
  • 05:59: If you see water in the atmosphere and the temperature is right, it potentially exists as a liquid on the surface.

2017-08-16: Extraterrestrial Superstorms

  • 04:50: ... is water, but the gas giants' atmospheres span such a wide range of temperature and pressure that all sorts of molecular species ...

2017-08-02: Dark Flow

  • 01:49: In all directions, it appears to be the same temperature-- around 2.7 Kelvin-- and hence, the same microwave wavelength.
  • 01:57: Actually, when we look at the CMB from our moving platform of planet Earth, we don't see a perfectly even temperature.
  • 03:39: ... bathed in a diffuse but searing hot plasma-- hydrogen and helium, with temperatures up to 100 million ...

2017-06-21: Anti-Matter and Quantum Relativity

  • 12:56: It's the size of the consistently low temperature region that's unusual.
  • 15:43: Many of you noticed that we misprinted the typical deviation of the cosmic microwave background temperature by a little.

2017-06-07: Supervoids vs Colliding Universes!

  • 01:52: When it formed in the early hot universe, it was mostly infrared light with a temperature of 3,000 Kelvin.
  • 01:59: ... expansion later, and it stretched to microwave wavelengths, and to a temperature very close to 2.725 Kelvin all across the ...
  • 02:13: Although it's very smooth, the CMB does show lots of very tiny fluctuations in temperature.
  • 02:36: The typical deviation from the average temperature is around 20 microkelvin, so the differences are one part in 100,000.
  • 04:27: The photon exits with a net energy gain, which would register as a higher temperature on our CMB map.
  • 06:21: ... all four voids should only have produced 32 microkelvins of reduction in temperature in the CMB, which is a mere 1/5 of the observed 150 microkelvin ...
  • 09:53: Chang, Claiborne, and Levi, 2009, figured out that this should result in a temperature gradient across each universe.

2017-05-31: The Fate of the First Stars

  • 04:30: And by the ideal gas law, temperature increases with pressure.
  • 04:43: Now, the rate of nuclear fusion reactions is incredibly sensitive to temperature.
  • 04:49: A small increase in mass means a small increase in core temperature.
  • 07:37: Pressure and temperature have time to equalize across the cloud before it breaks apart.

2017-05-10: The Great American Eclipse

  • 05:20: The sky's blue deepens, a breeze stirs, and the temperature drops.

2017-04-26: Are You a Boltzmann Brain?

  • 01:31: ... equilibrium with the gas outside the piston-- everything the same temperature and pressure, perfectly ...

2017-04-05: Telescopes on the Moon

  • 04:11: To start with, Earth's thick atmosphere is a powerful buffer against rapid changes in temperature.
  • 04:23: When exposed to the sun, temperatures rise to around 125 Celsius, well, above the boiling point of water.
  • 04:31: But put up some shade, and temperatures drop to minus 150 Celsius or lower.
  • 04:37: ... short roll on the lunar surface, Yutu was experiencing a massive temperature differential between its sunny side and shaded ...

2017-03-15: Time Crystals!

  • 05:43: This is sort of like the phase diagram of regular matter in which you plot pressure versus temperature.

2017-03-01: The Treasures of Trappist-1

  • 02:30: ... different chemicals condense at different temperatures, planets' distance from the star during formation largely determines the ...
  • 02:50: However, three of them now occupy their star's habitable zone, where planet's surface temperature would be just right for liquid water.
  • 03:48: ... with its star and the other planets could warm it to liquid water temperatures as ...
  • 04:08: We've already established that the temperature could be to our liking.
  • 06:41: All sorts of fascinating nasty compounds can end up in exoplanet atmospheres, all strongly affecting climate temperature and chemistry.
  • 07:59: That could seriously increase temperatures and volcanic activity and make it a real surfing mecca.

2017-02-02: The Geometry of Causality

  • 14:02: Well, although quasar accretion disks can reach some pretty crazy temperatures, they aren't particularly dense.

2017-01-19: The Phantom Singularity

  • 16:22: ... all of this is about what I'd expect when you generate temperature differentials and large magnetic fields around a very sensitive position ...

2017-01-04: How to See Black Holes + Kugelblitz Challenge Answer

  • 00:50: ... gravitational well of a black hole will reach incredible speeds and temperatures, causing the region around black holes to ...

2016-11-16: Strange Stars

  • 02:16: The remaining neutron star is millions of Kelvin in temperature, and may be spinning thousands of times per second.
  • 04:38: ... is forged by insane pressures, not by the greater-than-a-trillion-Kelvin temperatures of the Quark Epoch or the Large Hadron ...
  • 08:13: The x-ray data revealed a surface temperature of a more million Kelvin, much cooler than expected for a neutron star of its age.

2016-11-02: Quantum Vortices and Superconductivity + Drake Equation Challenge Answers

  • 00:21: These theoretical physicists pioneered work in the understanding of phase transitions of materials at temperatures close to absolute zero.
  • 00:36: ... example: going from a gas to a liquid to a solid as temperature drops, and the motion of individual particles in the material gets ...
  • 00:44: However, at extremely cold temperatures, this thermal motion is so small that quantum effects can dominate the behavior of certain materials.
  • 01:33: ... extremely low temperatures, the spins of a material's particles tend to line up, but you get these ...
  • 02:00: ... how the splitting of vortex pairs destroyed superconductivity at higher temperatures. ...

2016-10-12: Black Holes from the Dawn of Time

  • 12:39: In addition, water has an extremely high specific heat, meaning it takes a lot of energy to change its temperature.

2016-09-29: Life on Europa?

  • 03:21: ... deep ocean where noxious gases spew out from Earth's mantle and water temperatures exceed 100 degrees ...
  • 04:12: These critters are highly adapted to the extreme temperatures and sulfur-rich environments.

2016-08-10: How the Quantum Eraser Rewrites the Past

  • 12:25: The increasing temperature of the sun will cause all of Earth's oceans to evaporate in a billion years, plus or minus, depending on the model.

2016-07-27: The Quantum Experiment that Broke Reality

  • 11:58: It's called "the Jeans mass." It depends on cloud size, temperature, rotation rate, and composition.

2016-06-22: Planck's Constant and The Origin of Quantum Mechanics

  • 02:43: For example, along with the sun's temperature, it sets the color of sunlight.
  • 03:30: And so the average frequency of the resulting particles of light, of photons, increases with temperature.
  • 04:04: Your temperature is around 310 Kelvin, so your heat glow is mostly in low frequency infrared photons.
  • 09:10: ... once you know the Planck law and an object's temperature, you can calculate the Planck constant just by finding the brightest part ...

2016-06-08: New Fundamental Particle Discovered?? + Challenge Winners!

  • 01:16: The resulting collisions can produce temperatures of several trillion Kelvin.
  • 06:30: In fact, over the past 35 years, it's decreased while temperatures continue to increase.
  • 06:48: Well, temperature is following CO2.
  • 06:53: Global average temperature has risen by at least 0.6 degrees Celsius, probably closer to 1 degree since around 1900, following the CO2 increase.
  • 07:17: In the paleoclimate record, we see that an increase in temperature due to Earth's changing orbit proceeds an increase in CO2.
  • 07:31: But once initiated, it doesn't really matter whether the CO2 increased first, or the temperature increased first.
  • 08:05: But it rarely nails the exact temperature.
  • 08:19: ... current trends, I mean the increasing temperatures, more severe droughts, shifting climate zones, reduced ice coverage, et ...

2016-05-25: Is an Ice Age Coming?

  • 01:18: Temperatures rose, glaciers, and woolly mammoths migrated north, and humans thrived.
  • 05:31: ... floor sea life, whose composition also depends sensitively on ocean temperatures and salinity, and so also on global climate and ice ...
  • 06:01: Temperature goes up and down on the roughly 40,000-year time scale of changing obliquity.
  • 07:24: The vast oceans of the Southern Hemisphere provide a powerful buffer against changes in temperature.
  • 08:13: More ice means less absorbed sunlight, lowering global temperature and allowing even more ice to grow.

2016-03-02: What’s Wrong With the Big Bang Theory?

  • 01:45: Well, at temperatures above 10 to the 15, or a quadrillion Kelvin, it stops doing that.
  • 03:46: We do think that we can describe gravity and the shape of space time at these densities and temperatures.
  • 05:40: ... in the universe when the CMB was released was almost exactly the same temperature, around 3,000 Kelvin, varying from one patch to the next by at most one ...
  • 06:03: If you have a cup of coffee, and drop in some cold milk, it will all smooth out and become the same temperature after a bit of time.
  • 06:23: ... patch of the universe we can see in that direction to have the same temperature and density as the most distant patch in that direction, there needs to ...
  • 07:52: ... started subatomic, small enough that it was able to even out its temperature and then enter the state of insane, exponentially accelerating expansion ...

2016-02-24: Why the Big Bang Definitely Happened

  • 03:51: ... old and about 1,000 times smaller than it is today, it hit a critical temperature of 3,000 degrees Kelvin, at which point the entire universe slipped from ...
  • 05:02: But this mottled pattern shows there are imperfections, tiny differences in temperature of 1 part in 100,000 from one patch to the next.
  • 07:15: ... Big Bang theory tells us how long these elements were baked and at what temperature, and so predicts the proportions of deuterium, helium, and lithium that ...

2016-02-03: Will Mars or Venus Kill You First?

  • 06:26: Now, the pressure and temperature on the surface, 90 atmospheres and 450 degrees Celsius, will implode and roast you instantly.

2016-01-06: The True Nature of Matter and Mass

  • 09:55: At extremely high temperatures, the Higgs field takes on a value of 0 everywhere.

2015-12-16: The Higgs Mechanism Explained

  • 08:49: Gareth Dean asks about this whole thing about using gravitational waves to turn up the core temperature of a star.
  • 09:05: ... the core of a galaxy with merging super massive black holes should have temperatures raised by an observable amount by the gravitational ...

2015-12-09: How to Build a Black Hole

  • 01:20: If you get impatient, you can turn up the core temperature by bombarding it with gravitational waves.

2015-08-19: Do Events Inside Black Holes Happen?

  • 13:33: ... but they're highly, highly masked by the much more dominant effect of temperature variations and pressure variations on the atmospheric distribution ...

2015-05-27: Habitable Exoplanets Debunked!

  • 01:04: ... that star at which the energy from starlight would produce the right temperature on a planet's surface for water to remain liquid, provided the planet ...
  • 08:26: ... from an e equals mc squared perspective, your drop in body temperature alone would mean there's less thermal energy contributing to the total ...

2015-05-13: 9 NASA Technologies Shaping YOUR Future

  • 04:45: Inside a space suit, a rise in core body temperature from overexertion could be incredibly dangerous since there's no easy way to get that heat out.
  • 04:54: So how do you monitor a person's core temperature when that person is inside a space suit, floating in space?
  • 05:00: How about a pill that takes your temperature?
  • 05:05: Literally a pill with sensors and transmitters that takes your temperature from the inside.

2015-04-09: How to Weigh a Fart

  • 00:05: ... output is between half a liter and 2 liters of gas once cooled to room temperature. ...

2015-04-08: Could You Fart Your Way to the Moon?

  • 01:21: ... propellant oxidizes, chemical bond energy is released, raising its temperature and causing it to expand until it becomes a gas of particles bouncing ...

2015-04-01: Is the Moon in Majora’s Mask a Black Hole?

  • 07:57: No, but not because of temperature or pressure issues.

2015-03-25: Cosmic Microwave Background Explained

  • 02:04: Now, everything has a temperature, so everything has a thermal spectrum, and it emits all electromagnetic wavelengths.
  • 02:17: And those random motions are themselves a reflection of temperature.
  • 02:21: ... if you go really low in temperature, down to 2.7 degrees above absolute zero, the peak shifts way into ...
  • 02:42: There's nothing really in there to have a temperature, much less the very specific temperature of 2.7 Kelvin.
  • 03:00: During that era, a supercharged particle with a temperature of several thousand degrees permeated all of space.
  • 03:06: At this temperature, it's too hot for electrons and protons to even coalesce into atoms, let alone stars, planets or galaxies.
  • 03:51: Now as this plasma cooled, its temperature eventually dropped below the 3,000 or so degree mark, where neutral atoms could finally form.

2015-03-04: Should We Colonize Venus Instead of Mars?

  • 03:16: See, there's a teensy problem with temperature.
  • 04:17: First, the temperature drops to only about 70 degrees Celsius.
  • 04:21: ... equipment on Earth can withstand proximity to forest fires with temperatures that reach over 2,000 degrees ...
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