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

  • 07:12: After all, heat in solids comes from the vibrational motion of its atoms, and that vibration is transferred around by phonons.
  • 10:00: That motion, as we know, causes resistance.

2022-10-19: The Equation That Explains (Nearly) Everything!

  • 04:05: ... are other ways to get these equations of motion, but Lagrangian is especially powerful because of how it respects ...
  • 09:15: All these kinetic terms are summarized with the F’s, representing the motion of the bosons and their interactions with each other.

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

  • 10:07: ... On top of this, the entire Einstein ring will be moving due to the motion of the   exoplanet but also due to the wobble of the ...

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

  • 16:59: Jeremiah Young asks whether relativistic time dilation occurs due to the thermal motion of particles.

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

  • 03:20: ... really have a temperature, it has a velocity - but the average energy of motion of all water molecules is its ...
  • 08:32: In regular thermodynamics, the lowest energy corresponds to absolute zero temperature, which in turn means zero motion of particles.
  • 08:40: ... lowest energy state of a time crystal involves real motion, which makes them thermodynamically different than other states of matter ...
  • 10:24: The frequent interactions between people cause liquid-like phenomena like currents and waves as individuals lose their autonomy of motion.

2022-05-25: The Evolution of the Modern Milky Way Galaxy

  • 01:41: ... Campanas, enormous surveys   have tracked the positions and motions of more  than a billion Milky Way stars. We’re now able   ...
  • 06:57: ... stellar positions.   That enables the telescope to detect tiny motions,  which in turn allows astronomers to reconstruct   detailed ...

2022-05-04: Space DOES NOT Expand Everywhere

  • 01:24: ... clusters. But if you expand your view to large enough scales, that local motion or “peculiar velocity” is small compared to the fact that distant points ...

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

  • 05:38: ... move randomly, but as the system cools down  this random thermal motion gets overpowered by the   magnetic interaction and they end up ...
  • 06:32: ... back and forth in a valley. The equations   describing its motion are symmetric between  left and right because the valley is ...

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

  • 03:35: That gave him equations of motion that described how the universe must evolve.
  • 17:32: For example, if a particle races past you you observe its chirality based on its direction of motion.

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

  • 04:15: Planets make stars wobble, and that motion induces something called Doppler shift in the star’s emission lines.
  • 04:58: But the more edge-on the orbits, the more motion there is in the radial direction, and so the more chance of spotting the wiggling spectrum.
  • 06:12: That would then be the length of the year of a hypothetical exoplanet responsible for that motion.

2022-02-16: Is The Wave Function The Building Block of Reality?

  • 08:02: ... mechanism was a randomly jiggling field, like the frenetic Brownian motion of pollen grains floating on water. Matter’s interaction with this ...
  • 11:09: ... then the constant jiggling and acceleration caused by this Brownian motion means it will emit radiation. Last year, scientists working in Trieste, ...

2022-02-10: The Nature of Space and Time AMA

  • 00:03: ... in special relativity okay so the answer is that two types of motion are indistinguishable the motion of two galaxies moving apart because ...

2022-01-27: How Does Gravity Escape A Black Hole?

  • 02:02: For example we have gravitational waves - ripples in spacetime caused by certain types of motion.
  • 05:34: Depending on how you think about it, the curvature or the motion of each patch influences the next.

2022-01-19: How To Build The Universe in a Computer

  • 02:04: ... with a pair of these light-bulb-galaxies next to each other, with the motion of each bulb existing only as a note on a piece of ...
  • 03:53: In an N-Body simulation Newton’s laws of motion and gravity are applied over a series of time steps.

2022-01-12: How To Simulate The Universe With DFT

  • 07:15: In the Newtonian case, particles only interact locally, and that means the Newtonian equations of motion are what we call separable.
  • 07:46: ... fact in Newtonian mechanics we can not only write down the equations of motion for each particle separately, we can write the x, y, and z equations of ...
  • 10:54: Because they aren’t interacting, the equations of motion for these electrons are separable, just like in Newtonian mechanics.

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

  • 16:33: ... freefall in a gravitational field is fundamentally the same as inertial motion in free space. That means that an observer falling through a black hole ...

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.
  • 02:27: But these few numbers emerge from the motion of every air molecule — and to describe that we’d need the positions and momenta of 10^27ish particles.

2021-11-10: What If Our Understanding of Gravity Is Wrong?

  • 03:53: ... has a minimum strength - or by a modification to Newton’s 3rd law of motion, in which case the acceleration produced by a force has a minimum ...
  • 08:15: ... we saw that the principle of least action  allows equations of motion to be extracted in a way that automatically obeys all of our ...

2021-11-02: Is ACTION The Most Fundamental Property in Physics?

  • 01:22: ... - but to no avail. In the meantime Isaac Newton came up with his laws of motion which gave us the instant and miraculous power to explain the motion of ...
  • 02:11: ... Consider again the ball flying through the air. We can describe that motion without the painful vectors if we use ...
  • 06:47: ... Lagrangian into the Euler-Lagrange equation, you get equations of motion correctly describing the orbit of Mercury around the ...
  • 07:09: ... principle can be made to be “Lorentz invariant” - it gives equations of motion that are valid even in the shifting frames of Einstein’s relativity. And ...
  • 14:57: ... of the highest order, and we're delighted that our equations of motion have joined ...

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

  • 00:46: the laws of thermodynamics or Newton’s laws of motion Step 3.
  • 04:21: The power of constructor theory is that it allows us to explore physics without having to solve the detailed equations of motion.
  • 05:11: We use that state as the input, apply the laws of gravity and motion - and we find the output state - that the apple fell to the ground.
  • 06:06: David Deustch gives the example of the perpetual motion machine of the first kind - a device from which infinite energy can be extracted.
  • 06:36: We’d need a separate mechanistic approach to rule out every different type of the perpetual motion machine.
  • 12:30: ... their apparent path is just   the averaging out of all of this motion. There’s a LOT to unpack here. First on the   question of ...

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

  • 00:10: ... quantum tunneling - both theory and experiment - show that superluminal motion may be possible, while still managing to avoid the paradox of ...
  • 00:40: ... power that makes the quantum world weird - it’s also that the tunneling motion may move particles faster than they could travel if the barrier wasn’t ...
  • 03:01: ... according the the Schrodinger equation - which is just the equation of motion of ...
  • 05:22: Now, our old pal Professor Einstein is not a fan of faster-than-light motion.
  • 06:55: Certain definitions seem to imply faster than light motion.
  • 06:58: But that’s also true of motion without a barrier.
  • 07:57: These new guys use the Dirac equation, which properly incorporates special relativity and so we can take any emerging FTL motion more seriously.
  • 12:11: Is faster-than-light motion or influence possible?

2021-10-05: Why Magnetic Monopoles SHOULD Exist

  • 01:51: ... or or a circular electric current there’s a sense of electric charge in motion. ...

2021-09-21: How Electron Spin Makes Matter Possible

  • 13:25: ... to use spinors in the Dirac equation - which is the quantum equation of motion for electrons and other spin-½ ...

2021-09-15: Neutron Stars: The Most Extreme Objects in the Universe

  • 02:00: ... along the poles of the magnetic field,   and their motion in those jets results in  the radiation that we observe as ...

2021-09-07: First Detection of Light from Behind a Black Hole

  • 04:57: This gas starts to glow in a different way - not from heat, but from the motion of electrons between their atomic energy levels.
  • 05:22: But in a quasar, the gas is moving fast, and that motion shifts the wavelengths of the light as we see it.
  • 08:42: It turns out that all three types of motion are seen in different quasars.

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

  • 05:01: ... way to get distances to stars is with stellar parallax. That’s when the motion of the Earth causes a star to appear to move relative to more distant ...
  • 09:51: ... A collision like this could well produce the sort of turbulent motion to jump start a dynamo powerful enough to produce the observed magnetic ...

2021-07-21: How Magnetism Shapes The Universe

  • 02:30: ... particle will feel a force perpendicular to both its direction of motion and to the field lines - and the net result of that is that charged ...
  • 02:43: ... if that charge already has a circular motion - for example the electric current in an electromagnet, or the aligned ...
  • 05:11: Although it’s less of a sphere and more of a teardrop - dragged into that shape by the Sun’s orbital motion through the galaxy.
  • 07:09: These fields drive the motion of lone electrons throughout the interstellar medium.

2021-07-13: Where Are The Worlds In Many Worlds?

  • 02:13: You can calculate the overlapping pattern at any point in time by calculating the motion of all ripples separately and then adding them together.
  • 02:20: And the complexity of the sum has no effect on the motion of the individual.
  • 02:30: ... seems to hold no record of the shapes of the incoming waves, and yet its motion perfectly regenerates those waves, which travel on as though nothing ...

2021-07-07: Electrons DO NOT Spin

  • 02:25: ... an electron as a ball of charge moving in circles around the atom, that motion  leads to a magnetic moment - a dipole magnetic field like a tiny bar ...
  • 10:33: ... Noter's theorem, the invariance  of the laws of motion to changes in coordinate location gives us the law of the  ...

2021-06-23: How Quantum Entanglement Creates Entropy

  • 01:02: ... a temperature,   which is a measure of the average energy of motion of all the individual air molecules. But a single   air molecule ...
  • 16:20: ... restricted only to adjacent cells,   and B) in such quantized motion, would certain types of motion be ...
  • 16:39: ... weird effects that depend on orientation. Diagonal   motion would be different from rectilinear motion. There would be ...

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

  • 05:13: In that motion they produce thermal radiation that includes every possible wavelength of light.

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

  • 11:24: ... towards us. An invading fleet of Proximans? More plausibly from the motion of a planet around the star. Now there are very good reasons to think ...
  • 14:48: ... will come into play for things like warp drives, whose superluminal motion must allow time travel. A simple example is that the extreme curvature ...

2021-04-21: The NEW Warp Drive Possibilities

  • 02:46: ... think of space itself as moving - and there’s no limit to the relative motion of two patches of space - and so objects in those patches could have ...
  • 09:39: In previous work, this wave only waved in the direction of motion.
  • 09:45: ... spaceship, while the exotic matter is in a ring around the direction of motion. ...
  • 10:01: ... found that by including components of the wave motion that were perpendicular to the direction of motion he could build a ...

2021-03-23: Zeno's Paradox & The Quantum Zeno Effect

  • 01:15: ... if we’re talking about a quantum arrow, there may be a way to freeze its motion simply by looking at it, through the aptly named quantum Zeno ...

2021-03-16: The NEW Crisis in Cosmology

  • 08:03: ... Space Agency’s   HIPPARCOS satellite, which tracked the motion of 100,000 stars in our local patch of the galaxy But to really ...
  • 17:08: ... passing star destroyer in hyperspace - it’s   superluminal motion reversed the apparent causal ordering. In other words, shot first, ...

2021-03-09: How Does Gravity Affect Light?

  • 04:10: These are the ticks of a clock, and the frequency dictates the frequency and the wavelength of the photon produced by that motion.

2021-02-24: Does Time Cause Gravity?

  • 01:56: Absent a gravitational field or any forces, if the teapot starts motionless it stays that way.
  • 02:02: At least, it stays motionless with respect to the three dimensions of space.
  • 05:03: ... this is the motion of any object in a gravitational field - it gradually picks up velocity ...

2021-02-17: Gravitational Wave Background Discovered?

  • 00:00: ... and contract in succession at right angle to the direction of the wave's motion in what is known as a quadrupole wave if the wave passes through a ring ...

2021-02-10: How Does Gravity Warp the Flow of Time?

  • 05:38: Time dilation due to motion is inevitable if we accept the axiom of the constancy of the speed of light.
  • 06:43: So we can approximate its motion as a straight line.
  • 10:17: ... note of caution: be aware that circular orbital motion in a gravitational field is very different from our rotating space ...

2021-01-19: Can We Break the Universe?

  • 01:18: And the spaceship would also appear squished in the direction of its motion in what we call length contraction.
  • 04:33: ... the spacetime diagram, the set of simultaneous events for a motionless observer lie on a horizontal line - all events corresponding to your ...
  • 05:20: But those lines are tilted due to that motion, and they tilt one way on the outward journey and the opposite way on the return.
  • 08:31: Remember, length contraction causes moving objects to appear foreshortened in the direction of motion.

2021-01-12: What Happens During a Quantum Jump?

  • 03:40: ... of quantum jumps to that of epicycles—the long dead theory about the motion of the planets in an Earth-centered solar ...

2020-12-22: Navigating with Quantum Entanglement

  • 03:31: This “geomagnetic” field is generated by the convective motion in Earth’s outer core - which is a churning liquid mass of white-hot nickel and iron.

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

  • 07:29: They become almost motionless within the star, and slip into a regular grid pattern.

2020-11-18: The Arrow of Time and How to Reverse It

  • 01:38: ... don’t care about the direction of time? Basically, if you reversed the motion of all particles in the universe - sent them back exactly in the ...
  • 02:31: ... laws of motion combined with Coulomb’s law perfectly describe how the electrons’ ...
  • 07:17: ... across our universe - in the form of galaxies - we don’t see random motion. We see galaxies racing away from each other, which means they were once ...

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

  • 02:56: QED is what we call a gauge theory - its force-carrying fields and particles arise from the symmetries of the quantum equations of motion.
  • 05:01: Quantum mechanical equations of motion like the Schrodinger equation describe how the wavefunction evolves through space and time.
  • 05:54: So that is gauge theory in a nutshell: it explains a force by imposing symmetries on the equations of motion.
  • 07:08: Imposing this U(1) symmetry on our equations of motion led us to something very real and physical - electromagnetism.
  • 07:46: If we require our equations of motion to respect SU(2) we have to introduce a new field with 3 degrees of freedom.
  • 09:16: ... possible for the equations of motion describing a system to have a particular symmetry - to not care about ...
  • 09:42: ... equations of motion governing the overall magnetisation of this material aren’t encoded with ...
  • 10:30: Even though the equations of motion say one direction is not preferred to the other, the ground state has randomly picked out a single direction.
  • 10:48: ... the equations of motion respect the symmetries that give us the necessary gauge field, but the ...
  • 12:33: We just asked what would happen if the equations of motion governing nature had certain symmetries.

2020-10-13: Do the Past and Future Exist?

  • 01:21: Newton was the first to come up with a set of laws that allow us to predict the motion of all objects in the universe.
  • 07:07: From your point of view, you are motionless.
  • 07:10: After all, motion is relative so we can define your motion as stillness.
  • 08:02: At the same time, their entire perception of the spacetime grid is warped due to their motion.

2020-09-28: Solving Quantum Cryptography

  • 15:10: Timescales may be driven by the timescale of the motion of plasma in the stars and by the size of these critters.

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

  • 13:43: ... theory, Ry706 says “adding epicycles upon epicycles can represent any motion is literally true by Fourier ...
  • 14:11: But then motion in a circle can be represented by 2 separate sine waves for displacement in the x-y directions.
  • 14:19: ... any arbitrarily complex orbital motion can be represented with enough sine wave pairs in a fourier series - ...

2020-09-08: The Truth About Beauty in Physics

  • 01:07: A prime example is our effort to understand the motion of the planets.
  • 01:12: ... within circles - what we call epicycles - needed to explain retrograde motion. ...
  • 02:04: Kepler’s three laws of planetary motion are arguably much less elegant than Copernicus’ simple model - a touch uglier.
  • 02:19: There IS an extremely simple, elegant law underlying planetary motion - it's Newton’s Law of Universal Gravitation.
  • 02:27: Not only can Kepler’s complicated laws be derived from Newton, but Newtonian gravity makes predictions far beyond the motion of the planets.
  • 05:32: ... and Ptolemy’s circles within circles within circles could describe the motion of anything, from a planet to a particle of air - but it wouldn’t ...
  • 05:59: ... himself felt a sense of aesthetic pleasure when he realized that the motions of both the moon and an apple could be explained by one piece of ...
  • 09:23: Same with Newton’s gravity, derived from observations of apples and the moon, but it predicts the motions of galaxies.

2020-08-24: Can Future Colliders Break the Standard Model?

  • 01:41: Once accelerated, the particles were typically slammed into a motionless target - often just a slab of metal.

2020-07-28: What is a Theory of Everything: Livestream

  • 00:00: ... you throw something or a catapult hurls a rock you can figure out the motions archimedes did a lot of stuff on that but other things they just sort ...

2020-07-08: Does Antimatter Explain Why There's Something Rather Than Nothing?

  • 02:12: ... a mirror; and time reversal, where all particles have their direction of motion and spins exactly ...

2020-05-18: Mapping the Multiverse

  • 02:29: ... is whipped into a vortex so fast that not even light can resist its motion. ...
  • 05:53: ... field is according to the geodesics of objects in freefall that start motionless relative to the gravitational ...

2020-05-11: How Luminiferous Aether Led to Relativity

  • 04:06: ... it would cause a sort of drag that would impede their apparently perfect motion. Newton also favoured his own corpuscular theory of light - light as tiny ...
  • 06:42: The key was to observe a change in the speed of light depending on the direction of motion.
  • 07:06: ... - or a wave - depends in a simple way on the velocity and direction of motion of the observer. This is Galilean relativity - after Galileo ...
  • 07:19: ... see changes in the apparent speed of light depending on our direction of motion. If you move relative to the aether then there should be a sort of aether ...
  • 11:04: ... wave propagation. The speed of light appeared to be independent of the motion of the ...

2020-05-04: How We Know The Universe is Ancient

  • 01:35: ... shift - the lengthening of the wavelengths of their light due to their motion. Then Edwin Hubble figured out the distances to these objects by watching ...
  • 04:40: ... from us due to the expansion of the universe - they also have random motion as they’re tugged by the gravitational fields of nearby galaxies and ...

2020-03-24: How Black Holes Spin Space Time

  • 04:26: ... in a flat sink doesn’t know about the hole - it only knows about the motion of the water around it. In fact it’s possible to construct a black hole ...
  • 07:50: ... In particular, the radial direction becomes time-like, so downward motion becomes as inevitably one-directional as time. Well, in the ergosphere ...
  • 12:36: ... many other factors. And World of Warships captures the feel of complex motion dynamics without sacrificing ...

2020-02-11: Are Axions Dark Matter?

  • 02:35: ... episode before long. For now it’s enough to know that the equations of motion of the strong force, derived with QCD, actually allow violation of CP ...
  • 04:33: ... at once. This bizarre structure for the vacuum alters the equations of motion that come from QCD, new terms get added and the strength of those terms ...

2020-02-03: Are there Infinite Versions of You?

  • 13:03: It's hard to write down a simple equation of motion when the coordinate system is changing.

2020-01-20: Solving the Three Body Problem

  • 00:20: ... when Isaac Newton published his Principia. Within it were equations of motion and gravity that transformed our erratic-seeming cosmos into a perfectly ...
  • 01:10: ... just one more body and in most cases all motion becomes fundamentally chaotic - there exists no simple solution. This is ...
  • 01:24: ... it mean to find a solution to the three-body problem? Newton’s laws of motion and his law of universal gravitation give us a set of differential ...
  • 02:06: ... Kepler figured out much about the elliptical solution for planetary motion 70 years before Newton’s laws were even ...
  • 03:18: ... there was much profit in learning to predict the gravitational motion of many bodies. For most of the three centuries since Newton, predicting ...
  • 05:25: ... an accurate prediction for most three-body systems you need to break the motion of the system into many pieces, and solve them one at a time. A ...
  • 06:09: ... step at a time is called numerical integration, and when applied to the motion of many bodies it’s an N-body ...
  • 06:20: ... modern computers, N-body simulations can accurately predict the motion of the planets into the distant future or solve for millions of objects ...
  • 07:56: ... computers. The key was to find three-body systems that had periodic motion - they evolve - sometimes in complex ways - back to their starting ...
  • 09:25: ... triangle defined by the orbits evolves. It turns out that the periodic motion on the shape-sphere appears much simpler and easier to analyze than the ...
  • 10:30: ... Leigh published this in Nature in December 2019. The thing about chaotic motion is that the state of the system seems to get randomly shuffled over ...

2020-01-13: How To Capture Black Holes

  • 09:53: ... disk, causing more shocks as gas is rammed together. All of this violent motion produces a flash of ultraviolet radiation - and those flashes may be ...

2019-12-02: Is The Universe Finite?

  • 12:30: ... experiments of quantum mechanics and use them to construct equations of motion, laws of physics, and systems of measurement based on the algebra of ...

2019-11-04: Why We Might Be Alone in the Universe

  • 05:59: ... iron inner core spins suspended in a molten metal outer core, and this motion generates a powerful magnetic field that protects Earth from dangerous ...

2019-10-15: Loop Quantum Gravity Explained

  • 06:20: It then gives a sort of equation of motion for how these metrics evolve through time.

2019-09-23: Is Pluto a Planet?

  • 02:27: Newton’s Laws of Gravity led to consistent predictability of the motion of the heavenly spheres.
  • 03:19: That same motion almost perfectly reflected the clockwork predictions of Newtonian mechanics.

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

  • 04:46: And that motion gets messier.
  • 05:10: ... all of this motion that together produces Earth’s magnetic field through a process called ...
  • 05:32: In that motion I just described, electrons and nuclei should all be moving together – so no electrical current.
  • 06:30: Now cut to the second type of motion in the outer core.
  • 09:51: ... events are just a natural part of dynamo behavior, in which the chaotic motion of outer-core fluid causes a tangling of magnetic field lines and a ...

2019-07-25: Deciphering The Vast Scale of the Universe

  • 06:34: ... those stars, that gives us an incredible understanding of the shape and motion of our home galaxy – once imagined to be the entire universe and now our ...
  • 07:18: ... latest studies of galaxy motion reveal that Virgo, the Milky Way, and a hundred thousand more galaxies ...

2019-05-16: The Cosmic Dark Ages

  • 00:24: ... ago. In this way we can peer back in time and literally see the past in motion. In fact we’re able to see some of the first stars and galaxies to ever ...

2019-04-24: No Dark Matter = Proof of Dark Matter?

  • 00:03: ... gonna call it fritz to understand how Fritz formed the team measured the motions of stars within that galaxy first some bright lots of stars globular ...

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

  • 13:14: ... last week we explored the bad science of perpetual motion machines and announced the winners of the perpetual motion challenge. ...
  • 13:27: ... points out that atoms are perpetual motion machines, and there are hydrogen atoms that have been ticking for the ...
  • 13:36: Well, I guess you could call the atom the best possible perpetual motion machine of the Third Kind.
  • 14:05: Now to remind you, the Brownian ratchet has this flywheel that turns a cog due to random motions of particles hitting the flywheel.
  • 14:38: ... a vacuum, that internal vibration is enough to randomize its rotational motion. ...
  • 14:58: ... chastised us for putting the ElectroBOOM video that debunks perpetual motion machines alongside all of the other videos that actually claim to have ...

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

  • 00:06: But there’s one bit of nonsense that is perhaps more persistent than all others: the perpetual motion machine.
  • 00:19: No working perpetual motion machine has ever been experiment verified.
  • 00:30: We have perpetual motion machines of the first kind - they violate energy conservation - they pump more energy out than they need to keep running.
  • 01:18: Designing a perpetual motion machine has a very long history and became quite the craze from the middle ages through the renaissance.
  • 01:23: The first well-documented design for a perpetual motion machine was from the 12th century.
  • 03:37: Before we get to modern perpetual motion machines, let’s take a look at some actually interesting ideas that illustrate the limit of the second law.
  • 04:00: Individual gas particles are moving around with random – or Brownian motion.
  • 04:50: That limit is defined by the most important – perhaps the only important perpetual motion system ever conceived: the Carnot cycle.
  • 05:30: ... gradient and then pump it back in again, making it a candidate perpetual motion ...
  • 05:52: The Carnot cycle is, in principle, a perpetual motion process.
  • 06:06: These are perpetual motion machines that do not attempt to generate energy – they just keep themselves running forever.
  • 06:14: After all, Newton tells us, an object in motion tends to remain in motion unless acted on by an outside force.
  • 07:17: And then of course there’s the gravitational radiation that will slowly sap the “perpetual motion” of celestial systems.
  • 07:25: The best-case scenario for a perpetual motion machine of the third kind is a very, very slow wind-down to stillness.
  • 07:34: Now that we've reviewed three types of possible wrongness in perpetual motion machines, let's look at some of the modern proposals.
  • 07:42: ... – often lots of wheels with lots of magnets, somehow powering their own motion and producing extra energy ...
  • 08:15: Now the purveyors of over-unity devices typically do NOT claim to have created perpetual motion devices of the first kind.
  • 08:29: ... most end up shifting their device to the second kind of perpetual motion: they violate the 2nd law of thermodynamics by extracting energy where ...
  • 09:20: At best you have a perpetual motion device of the third kind.
  • 09:26: Most modern perpetual motion builders aren’t so technical.
  • 09:54: ... the challenge question, in which I asked YOU to come up with a perpetual motion machine based on the funky notion of negative ...
  • 11:55: And I leave you with wise words from someone who designed quite a few perpetual motion machines himself.
  • 12:02: “Oh ye seekers after perpetual motion, how many vain chimeras have you pursued?
  • 12:11: “ da Vinci was ahead of his time in some ways – he knew perpetual motion was bunk even before the laws of thermodynamics came along.
  • 12:21: Had only da Vinci known that his own perpetual motion machines could’ve score him such cool swag from Space Time.

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

  • 12:55: ... take notes and measure scientific phenomena, such as light, sound, and motion, using your phone, tablet, or ...
  • 13:19: Today, it's the 'Crisis in cosmology' and 'Negative mass perpetual motion' episodes.
  • 16:26: ... attract and opposite masses repel, but you don't get the crazy runaway motion that occurs if you put both positive and negative masses in the same ...
  • 16:37: So, no perpetual motion machines.

2019-01-30: Perpetual Motion From Negative Mass?

  • 00:13: Because you could use negative-mass apples to build warp drives, travel in time, and construct a perpetual motion machine.
  • 10:58: ... – are the GR analogs of Newton’s second law and give the equations of motion of ...
  • 11:10: ... or from Lagrangian mechanics – a more modern version of Newton’s laws of motion. ...
  • 13:18: ... accelerating positive and negative mass objects to build a perpetual motion ...
  • 14:21: Winning perpetual motion machines will be revealed in an upcoming episode of space time.

2019-01-24: The Crisis in Cosmology

  • 03:53: ...whose distances can be figured using stellar parallax Tracking their tiny motions on the sky, as Earth orbits the Sun.
  • 14:51: that they produce perpetual motion machines and paradoxes left and right.
  • 15:27: It's best thought of as a reversal of all motion,...
  • 15:39: ...then, if you reverse all motion,...
  • 17:13: As to the motion reversal symmetry of the T in CPT,...

2019-01-16: Our Antimatter, Mirrored, Time-Reversed Universe

  • 10:54: ... from. If the T in CPT is conserved then after reversing all particle motion those particles should perfectly retrace their steps and perfectly ...

2018-12-12: Quantum Physics in a Mirror Universe

  • 00:02: ... the balls trajectory those laws work the same no matter the direction of motion in fact if we rotate the whole mirror balls trajectory by 180 degrees ...

2018-11-21: 'Oumuamua Is Not Aliens

  • 07:37: Slightly weirder is that the tumbling motion doesn't seem affected by outgassing.
  • 09:51: One thing the lightsail doesn't explain is the tumbling motion.

2018-11-07: Why String Theory is Right

  • 06:05: ... do this, you basically take the classical equations of motion and follow a standard recipe to turn them into wave equations with ...
  • 06:21: This is a tricky process, and it only works if your equations of motion are especially friendly.
  • 06:31: It quantizes the equations of motion of slow-moving, point-like particles.
  • 07:17: Quantizing the motion of strings also starts out ugly, but there are also some math tricks to make it work.
  • 10:41: ... and write a nice, simple quantum wave equation from the equations of motion, but only for 1D strings making a 2D world sheet, not for any other ...
  • 11:28: So, with our quantized equations of motion in hand, you can predict the quantum oscillations of our string.

2018-09-20: Quantum Gravity and the Hardest Problem in Physics

  • 00:34: First, Einstein's relativity utterly changed the way we think about space, time, motion, and gravity.
  • 01:50: And the motion of objects is, thereby, altered.
  • 01:56: General relativity incorporates the earlier special relativity, which describes how our perceptions of space and time also depend on motion.
  • 09:03: If not, you could build perpetual motion machines, for example, using the Casimir effect.

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

  • 15:13: Another possible mechanism is through turbulence in waves generated by the rapid motion of magnetic fields.

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

  • 07:08: Weirdly, it's not in the measurement of particle trajectories or the motion of the door.

2018-07-18: The Misunderstood Nature of Entropy

  • 03:57: This theory explained thermodynamic behavior as the summed result of the individual motion of tiny particles under Newton's laws of motion.
  • 10:04: But entropy is also statistical and emerges from behavior of particles under the laws of motion.
  • 10:22: ... the laws of motion, whether Newtonian or quantum mechanical, don't care about the direction ...

2018-07-11: Quantum Invariance & The Origin of The Standard Model

  • 00:33: Our laws of physics are equations of motion tuned by the fundamental constants.
  • 01:35: ... the hill, sea level, even the center of the earth-- for the equations of motion of the ball, the altitude zero point is ...
  • 01:51: And we say that the equations of motion are invariant to that parameter.
  • 02:03: Newton's laws of motion and gravity, Maxwell's equations for electromagnetism, Einstein's general relativity, and of course, the standard model.
  • 02:31: That's the most basic equation of motion of quantum mechanics.

2018-07-04: Will A New Neutrino Change The Standard Model?

  • 03:46: Helicity is just the direction of a particle's spin relative to its direction of motion.
  • 04:10: Helicity depends on your own motion relative to the particle in question.

2018-06-13: What Survives Inside A Black Hole?

  • 03:31: In the good old rubber-sheet analogy, a heavy ball stretches the sheet downwards, affecting the motion of objects moving on that sheet.

2018-05-23: Why Quantum Information is Never Destroyed

  • 00:23: [MUSIC PLAYING] The laws of physics are equations of motion.
  • 01:34: ... conserved in a system by looking at the symmetries of the equations of motion. ...
  • 02:23: ... say that a system is time-reversal symmetric if its equations of motion allow us to perfectly predict the starting point simply by knowing the ...
  • 03:50: And the laws of motion say that A becomes C and B becomes D. If we look at the later state and see state C, we know A came first.
  • 04:21: We just set things up so our laws of motion force two possible initial states into the same exact final state.
  • 04:45: To get at this, let's think about the basic equation of motion of quantum mechanics.
  • 11:29: In a related question, AFastidiousCuber asks why free energy and perpetual motion machines are impossible?

2018-05-16: Noether's Theorem and The Symmetries of Reality

  • 03:03: In the case of Noether's theorem, when we say the environment stays the same, we mean the equations that give the laws of motion for the system.
  • 04:07: ... the last classic example, if the factors driving the laws of motion are symmetric under rotation-- for example, the spherically-symmetric ...
  • 06:43: ... principle of least action can be used to derive the laws of motion from the equations of classical mechanics to Feynman's path integral ...
  • 12:10: ... fitting laws of motion to the stars' five-year trajectory, there's only a very narrow ...

2018-05-09: How Gaia Changed Astronomy Forever

  • 01:47: As it traverses its orbit, Gaia detects the tiny shifts in the positions of stars due to this motion, a phenomenon called stellar parallax.
  • 02:00: And the degree of motion depends on this distance.
  • 04:49: ... the stretching or compression of the wavelength of starlight due to the motion towards or away from ...
  • 05:00: Combining motion on the sky and Doppler shift, gives the full three-dimensional velocities for these billion stars.
  • 08:33: Every dot of light in this picture is a star, with its past and future motion now known.

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

  • 01:07: The particles that make up any system all have some degree of random motion.
  • 01:13: That random motion tends to drive the system towards the most common arrangement of particles.

2018-03-28: The Andromeda-Milky Way Collision

  • 03:32: But Doppler shift measurements only gives the line of sight velocity, the component of the galaxy's motion directly towards or away from us.
  • 03:55: The galaxy is so far away that its motion relative to background galaxies is almost imperceptible.
  • 04:01: ... a transverse velocity equal to its line of sight velocity, Andromeda's motion over several years, in terms of angle on the sky, would be minuscule, a ...
  • 04:40: Then they averaged the observed motion of all of those stars and removed the effects due to the rotation of Andromeda and the motion of the sun.

2018-02-28: The Trebuchet Challenge

  • 01:59: ... then we can keep track of the potential for future gains or losses of motion. ...
  • 02:14: ... the right way, the sum of kinetic and potential energy, or motion and potential for motion, remains constant, and not just for one ...
  • 04:46: ... it's possible to figure out the equations of motion of a trebuchet in terms of Newton's laws, with a complicated series of ...
  • 05:25: No energy is transferred to the structure of the trebuchet through friction or other motion.

2018-02-21: The Death of the Sun

  • 11:07: It tells you the kinetic energy that will be gained or lost in motion between two points due to the work done by that force.
  • 11:14: Alternatively, it's the work that will be needed to be done against that force in order to execute that motion.

2018-02-14: What is Energy?

  • 01:05: It was 17th century polymath Gottfried Leibniz who first figured out the mathematical form of what we call kinetic energy, the energy of motion.
  • 05:17: You trade with perfect efficiency between motion and the potential for motion.
  • 07:08: Newtonian mechanics is great at describing the motion of simple systems of a few rigid objects.
  • 08:12: It produces the same equations of motion as Newtonian mechanics but without having to keep track of those innumerable fiddly force vectors.
  • 08:25: ... equation describes the motion of individual particles but can also describe the evolution of extremely ...
  • 08:50: ... energy of a quantum system and allows us to describe anything from the motion of a single particle in Schrodinger's equation to complex interactions ...

2018-01-31: Kronos: Devourer Of Worlds

  • 04:47: ... incredibly unlikely that they would end up tracking each other's motion so closely unless they were ejected from their birth cluster as a binary ...

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

  • 01:46: And although we can't hear this resonant vibration directly, we can see its effect in the changing brightness and the motion of the stellar surface.

2017-12-13: The Origin of 'Oumuamua, Our First Interstellar Visitor

  • 02:19: And astronomers realized that this is consistent with an elongated body with a tumbling motion.
  • 02:57: The weirdest thing about Oumuamua is its motion.
  • 05:25: PZ 17 performed more computer simulations to rewind the motion of both Oumuamua and the 3,700 stars within 100 light years of the sun.
  • 10:33: Does frequency then include information about direction of motion?
  • 10:53: And yes, also in their direction of motion, which is separate to frequency.
  • 11:03: ... we increase the uncertainty in its momentum and hence, its direction of motion after it exits the ...

2017-11-02: The Vacuum Catastrophe

  • 04:12: In fact, in both quantum mechanics and classical mechanics, a particle's equations of motion depend only on changes in energy.
  • 04:31: ... so you'll be able to knowledgeably scoff at zero point energy perpetual motion ...

2017-10-19: The Nature of Nothing

  • 01:03: Zero kelvin means no motion whatsoever in a substances constituent particles.
  • 01:21: Fix a particle's position, and its momentum, and so its motion, becomes a quantum blur of many possible momenta.

2017-10-11: Absolute Cold

  • 00:16: [MUSIC PLAYING] The mystical-seeming quality of heat is nothing more than the motion of a substance component particles.
  • 00:37: But what if we reduce temperatures so much that all particle motion ceases?
  • 02:07: They can only occupy certain energy levels of vibration or motion, much like the discrete electron orbitals in an atom.
  • 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.

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.
  • 05:38: ... magnetic fields produced by an electron's spin and by its orbital motion actually interact with each other in an effect called spin orbit ...

2017-09-13: Neutron Stars Collide in New LIGO Signal?

  • 14:38: ... by the Doppler method, which can measure the tiny wobble in a star's motion caused by the planet's gravitational ...

2017-08-10: The One-Electron Universe

  • 03:51: The direction, or sign, of that current depends on the direction of motion, but also on the sign of the charge.
  • 04:24: ... you get the same flipped sign whether you reverse the direction of the motion of the electron, or if you give it the opposite charge by turning it ...
  • 04:36: But reversing a particle's motion is mathematically the same as watching it in reverse time.
  • 04:43: ... ticking of the clock in the particles coordinate frame, its direction of motion appears reversed, which has the same effect as flipping its ...

2017-08-02: Dark Flow

  • 00:41: But there's no preferred direction to any of this motion.
  • 00:44: Motion due to the expansion of the universe-- what we call the Hubble flow-- is equal in all directions.
  • 00:51: The random motion of galaxies-- what we call peculiar motion-- should also have no preferred direction.
  • 02:05: This motion is due to the sun's orbit around the Milky Way and the Milky Way falling to the Great Attractor-- more on that last one soon.
  • 02:13: That motion causes the CMB to be Doppler shifted, its wavelengths a little stretched out behind and a little more compacted ahead.
  • 02:28: ... if the CMB is asymmetric due to our motion, there must be some reference frame, some velocity, in which there's no ...
  • 02:56: So the peculiar motion of galaxies can be defined as motion relative to the cosmic microwave background.
  • 03:13: Doing so has seemed to reveal that the motions of galaxies does not cancel out.
  • 10:53: Well, actually, the spatial positions and even directions of motions of particles in the diagrams don't mean much at all.
  • 11:13: The final directions of motions can be anything within the realms of possibility of physics.

2017-07-12: Solving the Impossible in Quantum Field Theory

  • 08:45: This impedes the electron's motion and actually increases its effective mass.

2017-07-07: Feynman's Infinite Quantum Paths

  • 05:06: For the large-scale classical universe, minimizing proper time lets you derive all equations of motion.
  • 09:59: Its motion can be described as changes in that excitation.
  • 10:10: ... includes motion of the photon, but it also includes the probability amplitude of a ...
  • 13:28: Just like air, the medium was imagined to have some preferred reference frame in which it was motionless.

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

  • 00:16: Einstein's theory of special and general relativity had changed forever the way we think about motion, space, and time.
  • 06:02: The Dirac equation perfectly predicts the motion of electrons at any speed, even in an electromagnetic field.
  • 13:05: Also, those wide spots near the center of the map are the result of Doppler shift due to Earth's motion through space.

2017-05-03: Are We Living in an Ancestor Simulation? ft. Neil deGrasse Tyson

  • 13:52: ... brain thought experiment fails because it assumes random particle motion, and that particle motion is actually ...
  • 14:02: Well, particle motion may be purely deterministic.
  • 14:36: ... resisted by more than just the improbability of the directions of their motion happening to point to that ...

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

  • 00:44: He showed that the laws of thermodynamics can be explained by thinking of gas as a collection of microscopic particles in constant, random motion.
  • 03:52: ... will happen to all end up in one corner of the room, due to their random motion. ...

2017-03-29: How Time Becomes Space Inside a Black Hole

  • 03:06: This equation assumes no orbital motion, only motion towards or away from the center of the black hole, which is a distance r away.

2017-03-22: Superluminal Time Travel + Time Warp Challenge Answer

  • 01:07: ... choosing the right path and the right reference frame, any superluminal motion can lead to information or objects returning to their origin before they ...
  • 02:28: There's no absolute notion of velocity, so everyone can be considered motionless from their perspective.
  • 02:34: Everyone draws their space time diagram time axis parallel to their direction of motion, because that's their experience of stillness.

2017-03-15: Time Crystals!

  • 02:16: Normal matter that is in what we call thermal equilibrium only has random internal motion.
  • 03:01: Wilczek proposed an actual substance that was in perpetual motion while in equilibrium.
  • 08:51: ... doesn't take much random motion from heat to scramble a carefully prepared array of entangled spin ...

2017-02-15: Telescopes of Tomorrow

  • 05:31: ... best astronomical observing in the world, even that air is in constant motion. ...
  • 08:44: We'll be able to track the motion of rogue high-velocity stars whizzing through our galaxy.

2017-02-02: The Geometry of Causality

  • 03:16: Motion at a constant velocity appears as a sloped line, and the time axis is scaled so that the speed of light is a 45 degree line.
  • 06:50: My world line is now speeding off to the left, while our traveler is motionless.

2017-01-25: Why Quasars are so Awesome

  • 04:24: It is swept up into a raging whirlpool around the black hole that we call an accretion disk, where its energy of motion is turned into heat.
  • 05:48: Oh, and if one of these jets happens to be pointed directly at us, then we see strange effects due to the near light speed motion of the jet material.

2017-01-19: The Phantom Singularity

  • 05:37: That motion is towards or away from the massive object, which is a distance r away.
  • 06:07: ... long as our objects world line doesn't require faster than light motion, then the square root of the space time interval is equal to the amount ...

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

  • 01:18: ... the motion of a visible star reveals it to be in orbit around a companion that is ...
  • 02:14: But more compellingly, we've tracked the motion of stars near the galactic core for many years.

2016-12-08: What Happens at the Event Horizon?

  • 05:44: And because we only have one dimension of space, and any motion to the left brings us closer to the black hole.

2016-11-30: Pilot Wave Theory and Quantum Realism

  • 03:59: This wave guides the motion of a real point-like particle that has a definite location at all times.

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

  • 00:36: ... going from a gas to a liquid to a solid as temperature drops, and the motion of individual particles in the material gets slower and ...
  • 00:44: However, at extremely cold temperatures, this thermal motion is so small that quantum effects can dominate the behavior of certain materials.

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

  • 03:10: Heat is just the energy in the random motion of particles comprising an object.
  • 05:28: This simple idea allowed our good Englishmen to figure out the frequencies of the photons produced by all of this thermal motion.

2016-06-01: Is Quantum Tunneling Faster than Light?

  • 09:28: But in the quantum realm, Heisenberg uncertainty does seem to allow instantaneous motion, and even perhaps causality violation within quantum limits.

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

  • 02:07: Earth's motion around the sun changes, and with it, the intensity and distribution of sunlight.

2016-05-18: Anti-gravity and the True Nature of Dark Energy

  • 05:33: And the motion of these particles results in a combination of relativistic corrections.
  • 09:38: Part of the problem is that negative pressure doesn't come from the motion of dark energy particles, whatever they might be.

2016-04-13: Will the Universe Expand Forever?

  • 03:14: As the apple rises, its kinetic energy, its energy of motion, is sapped by the gravitational field and converted into potential energy.

2016-03-23: How Cosmic Inflation Flattened the Universe

  • 10:39: So even though the gas originally had motion in many directions, over time, it sweeps into a single bog flow.
  • 11:40: It emerges in a rotating reference frame as a force-like term that resists inward motion.

2016-03-16: Why is the Earth Round and the Milky Way Flat?

  • 10:05: Disks happen when orbital motion dominates the resistance to gravity.

2016-01-27: The Origin of Matter and Time

  • 04:40: ... Einstein's special relativity at play here is the Galilean relativity of motion. ...
  • 11:14: That change in motion is an acceleration.
  • 11:16: And special relativity only describes the relative effects on time and space due to a constant relative motion.
  • 11:47: So for the Alcubierre warp metric, there's actually no time dilation either due to motion or acceleration.

2016-01-20: The Photon Clock Challenge

  • 00:35: And the resulting slowing of clock ticks due to motion is the time dilation of Einstein's theory of special relativity.

2016-01-13: When Time Breaks Down

  • 00:09: ... we're going to go even deeper and explore the connection between matter, motion, and the nature of ...
  • 01:11: ... held in place by protons that are comprised of quarks in constant motion. ...
  • 01:24: The sum total of this motion results in a smooth, consistent evolution of time.
  • 01:54: Because of motion.
  • 01:56: See, the flow of time depends fundamentally on motion.
  • 02:34: ... I want to show you why time depends on motion, which in turn will show us why light speed particles are timeless, and ...

2015-12-16: The Higgs Mechanism Explained

  • 02:35: ... can either be clockwise or counterclockwise relative to the direction of motion. ...

2015-11-25: 100 Years of Relativity + Challenge Winners!

  • 02:49: We just need to add enough velocity to Apophis to move it 25,000 kilometers relative to the frame of reference of its initial motion.

2015-10-22: Have Gravitational Waves Been Discovered?!?

  • 00:29: Instead, mass warps the fabric of 4-D spacetime, leading to what we see as gravitational motion.

2015-10-07: The Speed of Light is NOT About Light

  • 01:46: This Galilean Relativity is an incredible insight that Isaac Newton would later codify into his Laws of Motion.
  • 09:05: Mass is an impediment to motion.

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

  • 01:14: Fact-- events that happen at a normal rate, as far as the pony is concerned, will happen in slow motion according to me.
  • 01:44: ... he tumbles on, I see his rotation rate become more slow motion, but I also see him pick up translational speed, just as I would if he ...

2015-08-05: What Physics Teachers Get Wrong About Tides!

  • 00:00: [MUSIC PLAYING] As we've seen before on "Space Time," gravity affects the motion of all objects identically.
  • 12:39: ... should be-- that resemble-- that basically give you Newton's laws of motion as if there were a gravitational force-- are just the pieces of the ...

2015-07-22: SPECIAL ANNOUNCEMENT + Flat Spacetime Geometry Comments

  • 02:58: Remember, in Newtonian physics, there's no unambiguous answer to that question, because you can only talk about motion relative to other things.

2015-07-15: Can You Trust Your Eyes in Spacetime?

  • 07:16: ... a more standard drawing of motion over time, like what you might see in a physics 101 class, tangent ...
  • 07:29: Motion is relative.
  • 07:44: Instead, we want to represent some aspect of dynamical motion over time through space as a static geometric object.
  • 08:17: It's called the monkey's 4-velocity, even though that's a bit of a misnomer since there's no motion through spacetime.

2015-07-08: The Leap Second Explained

  • 00:30: Thus, in 1960, the second was redefined to be whatever would make the motions of multiple objects in the solar system fit Newton's laws of motion.

2015-07-02: Can a Circle Be a Straight Line?

  • 01:21: ... that last statement, and to explain how it lets you account for the motion we observe even if there's no Newtonian force of ...
  • 01:57: We'll end up seeing that all the supposedly gravitational effects on motion can be accounted for just by the geometry of spacetime.

2015-06-03: Is Gravity An Illusion?

  • 00:54: OK, bear with me for a minute because we need to begin with some Physics 101 and Newton's laws of motion.
  • 00:59: To analyze motion, you need what's called a frame of reference.
  • 01:06: The reason you need a frame of reference is that you can only measure motion relative to other things.
  • 02:51: And from the perspective of inertial frames, motion obeys a simple rule-- F equals ma.

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

  • 00:48: ... glove tries to improve dexterity and reduce hand fatigue and repetitive motion stress for astronauts working on equipment during space ...

2015-05-06: Should the First Mars Mission Be All Women?

  • 01:58: Women are more prone to space motion sickness when they first hit zero G, but that goes away.

2015-04-29: What's the Most Realistic Artificial Gravity in Sci-Fi?

  • 03:56: That apparent departure from straight line motion in rotating reference frames is called the Coriolis effect.

2015-04-22: Are Space and Time An Illusion?

  • 02:52: ... though two observers in relative motion will measure different distances and different elapsed times between the ...
  • 05:47: There's no motion through spacetime.

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

  • 09:00: The Earth has superimposed an individual motion through the galaxy.
  • 09:05: And due to that individual motion, there is in fact a Doppler shift of the CMB.

2015-03-25: Cosmic Microwave Background Explained

  • 02:12: In fact, it's called a thermal spectrum because the light is generated by the random motions of particles in the material.
  • 02:17: And those random motions are themselves a reflection of temperature.

2015-02-11: What Planet Is Super Mario World?

  • 00:21: Let's start with how gravity affects motion, because that a huge effect on jumping.
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