
20221208: How Are Quasiparticles Different From Particles?
 06:47: They have energy equal to the planck constant times their frequency.


20221019: The Equation That Explains (Nearly) Everything!
 10:36: ... the more indicies you need. Also, next to the charges are the coupling constants which represent the strength of each ...
 14:00: ... particle masses, or chooses coupling strengths like the fine structure constant we discussed recently. And it doesn't explain dark energy or the ...


20221012: The REAL Possibility of Mapping Alien Planets!
 15:45: ... we talked about the mysterious meaning of the fine structure constant. AJMansfield asks whether JWST also have a program for doing ...
 18:29: ... the quantum fields behave  including raising the fine structure constant. We routinely reach temperatures where the fine structure constant ...
 19:23: ... asks, If the fine structure constant wasn't constant (like during the big bang), wouldn't the relationship ...
 20:21: ... is true then we should expect other leetspeak messages in other constants. I looked, extensively and didn’t find anything. Bit ...


20220928: Why Is 1/137 One of the Greatest Unsolved Problems In Physics?
 00:19: This is the fine structure constant, and it appears everywhere in our equations of quantum physics, and we’re still trying to figure out why.
 00:30: ... fine structure constant, designated as the greek letter alpha, just looks like one of the many ...
 00:43: Like the speed of light, the gravitational constant, or Planck’s constant.
 00:57: ... question to the Devil will be: What is the meaning of the fine structure constant?” Even Richard Feyman pondered its mysteries his entire ...
 02:55: ... divided by four times pi, the permittivity of free space, Planck's constant and the speed of ...
 03:16: We see combinations of these sorts of important constants throughout the laws of physics.
 03:28: ... speed of light in meters per second, vacuum permittivity and Planck's constant also have their ...
 03:45: This number just happens to be 1/137.035999, the fine structure constant.
 04:34: And that’s just the tip of the iceberg for the appearances of the fine structure constant in the laws of physics.
 04:50: ... now more than 100 years after Sommerfeld discovered the structure constant, I’d like to tell you what it ...
 05:49: That base probability comes from the coupling constant or coupling strength for the interaction.
 05:55: And that’s exactly what the fine structure constant is: it’s the coupling strength of the electromagnetic force.
 06:23: So the Fine Structure Constant sets the "strength" of the electromagnetic force.
 06:37: So it’s starting to make sense why the fine structure constant appears in all of these formulas that depend on the electromagnetic force.
 06:46: ... does, and why does this specific combination of other fundamental constants come out to be exactly ...
 07:06: In fact the fine structure constant isn’t as constant as it sounds.
 07:13: The higher the energy, the larger the constant.
 07:16: ... the insane energies right after the Big Bang, the coupling constant for the EM field  which was then joined with the other forces, ...
 07:30: We’re now at the bottom of the energy scale, and the fine structure constant has bottomed out at 1/137.035999.
 08:03: ... constant sets the size of atoms  a larger value means electrons would be ...
 08:22: ... been estimated that if the fine structure constant were just a few percent different, carbon would never have formed ...
 08:33: ... ended up with this particular value for the fine structure constant or many of the other fundamental ...
 08:41: Many physicists believe that these constants were set more or less randomly at the beginning of the universe.
 08:49: ... of course there are many, many universes with different values for the constants. ...
 09:08: But the fact that the fine structure constant has such a convenient value isn’t the weirdest thing about it.
 09:36: You could try the various constants of nature to demonstrate that you knew advanced physics.
 09:43: The problem is, most of these constants require you to choose units of measurement.
 09:57: Try the gravitational or Planck’s constant and you also have to define the kilogram.
 10:10: But the fine structure constant is unitless.
 10:27: That’s handy for interstellar communication, but it also tells us that’s something's seriously up with the fine structure constant.
 10:52: But these things don’t pop up in all these unexpected places like the fine structure constant does.
 11:03: Let’s start by thinking about the similarly prolific constants of nature  the ones that actually have units.
 11:11: Those units tell us a lot about what those constants mean.
 11:15: They tell us that the constants of nature represent relationships.
 11:33: ... gravitational constant is the relationship between mass, distance, and gravitational ...
 11:46: The relationship is defined by the units of the constant.
 11:50: But without any units, it's not immediately clear what kind of relationship the Fine Structure Constant represents.
 12:08: If the other constants of nature tie various physical parameters together, perhaps the fine structure constant is what ties those constants together.
 12:17: ... about it this way  if the constants of nature were set randomly at the big bang, and were set independently ...
 12:43: ... fact that this canceling gives the fine structure constant, and the fine structure constant also represents the relationship between ...
 12:55: ... hints at a connection between the other fundamental constants  perhaps pointing to an underlying common mechanism that set the ...
 13:15: ... it could be that the fine structure constant is not a physical constant, but a mathematical one, like pi, but perhaps ...
 13:51: ... called the fine structure constant “one of the greatest damn mysteries of physics” and Poetically ...
 14:13: And perhaps that number was 1/137, the fine structure constant  whose value sets the rules of this particular space time.


20220921: Science of the James Webb Telescope Explained!
 13:19: This constant exchange process keeps the nucleons bound together, analogously to how the atoms in molecules are bound by the exchange of electrons.


20220824: What Makes The Strong Force Strong?
 06:07: We can think of each charged particle as generating a constant buzz of virtual photons around it, forming what we think of as its EM field.
 06:42: A pair of quarks bound into, say, a pion, are connected by a gluon field, also describable as a constant exchange of virtual gluons.
 19:18: The current age estimate of 13.7 billion years assumes a constant dark energy.


20220817: What If Dark Energy is a New Quantum Field?
 00:36: ... physical explanation for dark energy is that the vacuum of space has a constant energy density. Empty space buzzes with random activity that we ...
 01:25: ... dark energy is that it can be described with a socalled cosmological constant. This is just a static number that you can add to Einstein’s equations of ...
 03:22: Standard “cosmological constant” dark energy has omega 1. This is just what you get when you say that the vacuum has a constant energy density.
 05:50: ... number down to nearly zero but not quite zero. This is the cosmological constant problem, and we’ve discussed it ...
 06:25: ... second reason is the socalled Hubble tension.When we measure the Hubble constant  the current rate of expansion of the universe, based on supernova ...
 07:31: ... one could  and if that’s true then a lot of problems with cosmological constant dark energy could be solved. There are a few options for dark energy as ...
 09:51: ... the uncomfortable coincidences that seem necessary with a cosmological constant dark energy. Currently around 70% of the energy in the universe is dark ...
 10:08: ... expands, matter dilutes away while most versions of dark energy stay constant or relatively constant, or even increase in some models. The universe ...
 10:55: ... This same “tracker” behavior could also help solve the cosmological constant problem. If quintessence shifts to match the matter fields, it could ...
 11:51: ... of omega less than ⅓ means accelerating expansion, and omega 1 is a constant energy density. Quintessence is often used to refer to any omega between ...
 13:27: ... support for quintessence, because that would refute the cosmological constant model, and quintessence is its main competitor. The now fully ...
 14:41: ... us about its fabric, its origin, and its fate. Either the cosmological constant problem is coincidental with a quintessentially consistent dark energy, ...


20220803: What Happens Inside a Proton?
 05:14: ... 1/137 thing is the fine structure constant. It’s the coupling strength between the electron and ...
 06:02: ... the strong nuclear force is ingeniously named the strong coupling constant. It is much higher than the fine structure constant, of order 1, ...
 06:37: ... caveat that there are some unusual cases where the strong couple constant can become small and quarks can be understood with Feynman ...


20220615: Can Wormholes Solve The Black Hole Information Paradox?
 03:20: ... filled with a boiling flux of particle/antiparticle pairs that constantly appear and annihilate each other. If these ...


20220601: What If Physics IS NOT Describing Reality?
 08:49: ... particle’s position and momentum has to be greater than the Planck constant divided by ...


20220525: The Evolution of the Modern Milky Way Galaxy
 17:21: ... between the two?” Yes and no. First, assuming no cosmological constant and dark energy, the expansion of the universe does not ...
 18:10: ... metric isn’t really valid in a universe with a cosmological constant. There would indeed be an additional effect due to the tiny vacuum ...
 18:41: ... Rose has a similar hypothesis that all matter is constantly shrinking within a static space. Listen, guys, I understand ...


20220504: Space DOES NOT Expand Everywhere
 08:21: ... there is no constant tug of war between the expanding universe and the gravitationally bound ...
 10:52: ... stays the same  it’s just defined as a combination of the Gravitational constant, the Planck constant, and the speed of light  so if those aren’t ...


20220323: Where Is The Center of The Universe?
 12:09: ... one of his solutions, matter was distributed with constant density across a spherically symmetric cloud, but beyond that cloud the ...


20220216: Is The Wave Function The Building Block of Reality?
 11:09: ... If the quantum object happens to be electrically charged, then the constant jiggling and acceleration caused by this Brownian motion means it will ...
 18:37: ... Time to a black hole, in which it’s captivating and radiates information constantly. Well thank you dannymac63. But remember, we don’t know whether black ...


20220210: The Nature of Space and Time AMA
 00:03: ... density of dark energy is added every time you you you it is well is a constant okay it's like you're adding more dark energy every time you add a new ...


20220119: How To Build The Universe in a Computer
 03:59: ... enough that we can assume that the global gravitational field is constant  it only changes in the next step, after all the particles have made ...
 08:35: ... particles within the fluid  those particles effectively make up a constantly shifting ...


20211110: What If Our Understanding of Gravity Is Wrong?
 11:28: In 2020 Constantinos Skordis and Tom Złosnik proposed a new relativistic version of MOND, and just last month their paper passed peer review.


20210818: How Vacuum Decay Would Destroy The Universe
 10:54: ... decay bubble. But that was unfounded. After all, Earth is constantly being bombarded by cosmic rays of much, much higher energy ...


20210803: How An Extreme New Star Could Change All Cosmology
 16:29: ... Unlike isotherms and elevation contours, they don’t represent lines of constant field. Rather they represent the lines of steepest gradient in that ...


20210713: Where Are The Worlds In Many Worlds?
 11:57: For example, worlds don’t split constantly and irreversibly.


20210707: Electrons DO NOT Spin
 00:47: ... vertical magnetic field. The cylinder immediately starts rotating with a constant speed. At first glance this appears to violate conservation of angular ...
 12:13: ... can only be observed as plus or minus a half times the reduced Planck constant, projected onto whichever direction you try to measure it. We call ...


20210623: How Quantum Entanglement Creates Entropy
 15:02: ... For an exponential process, the rate of doubling stays constant. Of course, the rate of doubling doesn’t have to stay constant, ...


20210616: Can Space Be Infinitely Divided?
 01:16: ... number that appears in his equation  the Planck constant. It represents the chunkiness of thermal radiation. ...
 02:21: ... the Planck constant comes the Planck length. It’s the length you get when you ...
 02:38: ... 10^35 m. But why is this randomseeming combination of constants so important? Well, it represents the scale at which space ...
 04:30: ... photon’s momentum is the Planck constant divided by its wavelength. So just replace photon momentum ...
 05:08: ... uncertainty principle we see that the Planck constant represents the limit to which we can measure the universe. We ...
 06:39: ... by a factor equal to the effective mass times the gravitational constant divided by c^2. Let’s replace the mass with the ...
 07:48: ... why the Planck length is this combination of fundamental constants  it’s the wavelength of a photon that creates a black ...


20210519: Breaking The Heisenberg Uncertainty Principle
 07:35: ... of probability, where the area of the circle is proportional to Planck’s constant, satisfying the uncertainty ...


20210323: Zeno's Paradox & The Quantum Zeno Effect
 06:00: A constant radiofrequency field is tuned to cause electrons to oscillate smoothly between two energy levels  call them 1 and 2.


20210316: The NEW Crisis in Cosmology
 01:16: ... rate of the universe, typically expressed as Hubble’s constant after Edwin Hubble, the guy who first properly measured it back in ...
 04:42: ... can give us the expansion rate. The Planck team calculated a Hubble constant of 67.6 km/s/Mpc  let’s not worry about the ...
 05:31: ... A couple of years ago his team published a new Hubble constant of 73 and a half.+/ 1.5 ...
 05:52: ... Hubble constant assumes that dark energy has had a constant density for the entire age of the ...
 09:17: ... gave Adam Reiss and team a refined measure of the Hubble constant. So what do you think  do the supernova and Planck results ...
 10:08: ... to be coming on the side of the Planck result  a Hubble constant in the high ...
 10:40: ... so the uncertainty is large  but published results give a Hubble constant in the low 70s  so in agreement with the supernova guys. ...
 11:57: ... waves from merging black holes to measure the Hubble constant. These waves get stretched by the expanding universe, just ...
 12:52: ...  I mean seriously, we don’t even know what Hubble’s constant is. But your support grants some much needed stability to spacetime ...


20210224: Does Time Cause Gravity?
 00:34: ... two axioms of Einstein’s relativity theory: that the speed of light is constant for all observers, and that the weight induced by acceleration is ...


20210210: How Does Gravity Warp the Flow of Time?
 04:33: But let’s say the gerdankenlab is moving at a constant velocity past a stationary physicist.
 08:15: ... lines of constant time for the moving clock tilt back and forth, and as that line tilts it ...
 09:53: ... if you consider the traveling twin to be in a gravitational well with a constant acceleration equal to her spaceship’s ...


20210126: Is Dark Matter Made of Particles?
 10:33: ... and their antimatter counterparts would have been popping into existence constantly, borrowing energy from the crazy radiation of that ...


20210119: Can We Break the Universe?
 05:12: ... the spacetime diagram, that’s whenever one of these lines of constant time extending from January 1st on earth crosses the spaceship’s path  ...
 06:41: A line of constant time for the former is just a circle around the cylinder.
 07:31: There’s a stationary frame of reference where lines of constant time are closed loops, while in every other frame they are endless helices.
 07:54: In the case of the closed universe, that closed topology DOES pick out a special frame  it’s the one with these closed constant time loops.
 11:15: Remember that the line of constant time is a helix.


20201118: The Arrow of Time and How to Reverse It
 03:12: ... states that this stuff called entropy must always increase or stay constant  entropy never decreases over time. So the 2nd law does dictate a ...


20201013: Do the Past and Future Exist?
 02:08: Newton assumed that all particles, all observers, all points in space were ruled by a single, constantly ticking clock.


20200908: The Truth About Beauty in Physics
 16:21: ... Constantine offers a different type of wisdom regarding the motivation for building ...


20200824: Can Future Colliders Break the Standard Model?
 01:32: ...  here the particles are still accelerated by electric fields, but now a constant magnetic field causes the beam to spiral outwards from its central ...


20200810: Theory of Everything Controversies: Livestream
 00:00: ... directly on what eric was just saying because it's something that i constantly get to hear usually from from physicists and not from mathematicians ...


20200728: What is a Theory of Everything: Livestream
 00:00: ... you guys know if you take the basic you know if you take the basic uh constants of nature uh you know planck's constant gravitational constant speed ...


20200615: What Happens After the Universe Ends?
 04:57: Lines representing constant distance or simultaneous times shift with the velocity of the observer.
 05:03: If I draw the line of constant time for all possible travelers passing by my position, I get these nested curves  hyperbolas.
 05:12: They show how time will tick for any constantvelocity observer passing through this point.
 05:23: ... time of something taking the most direct path between them  a path of constant velocity that reaches that point in space at the right instant in ...
 10:41: ... sort of conformal rescaling, the universe needs a positive cosmological constant. ...


20200527: Does Gravity Require Extra Dimensions?
 00:00: It’s been 120 years since Henry Cavendish measured the gravitational constant with a pair of lead balls suspended by a wire.
 08:55: ... of rotation Cavendish made the first measurement of the gravitational constant. ...
 09:34: The meticulous care paid off—Cavendish measured a gravitational constant that agrees with our modern value, with 1% uncertainty.


20200511: How Luminiferous Aether Led to Relativity
 06:48: ... classical waves travel at a constant speed relative to their medium. For example, sound waves travel at ...
 11:20: ... Galilean transformation that now allowed the speed of light to remain constant, no matter your ...
 14:23: ... let's pretend that the expansion rate is constant. And for an infinite universe the "size" is just the average distance ...


20200504: How We Know The Universe is Ancient
 06:22: ... rate is encapsulated in something we call the Hubble constant, which just tells how fast a galaxy is moving away from us given its ...
 08:58: ... had been using to get distances to galaxies, and so calculate the Hubble constant and the age of the universe. It’s similar to the Cepheid method because ...
 09:39: ... concluded that the expansion rate of the universe – the Hubble constant – was about 75 kilometers per second per megaparsec. Now, don't worry ...


20200407: How We Know The Earth Is Ancient
 08:25: ... produced when cosmic rays hit nitrogen in the atmosphere, resulting in a constant proportion of C14 within the atmospheric ...


20200331: What’s On The Other Side Of A Black Hole?
 03:46: ... horizon becomes is also a 45 degree line, even though it actually has a constant physical ...


20200224: How Decoherence Splits The Quantum Multiverse
 03:11: ... frequency and if the shape of the waves are the same, and if there’s a constant phase difference between them  the peaks and troughs either line up ...
 06:15: A constant phase offset will just shift the interference pattern to left or right on the screen.


20200218: Does Consciousness Influence Quantum Mechanics?
 15:01: ... we would get new quantum fields and new particles if other fundamental constants turned out to vary over space, in the same way that a variable theta ...
 15:19: So by the mathematical definition, a spatiallyfarying constant would be a field.
 15:46: You wouldn't get the same sort of energy structure by varying all of the other constants.
 15:49: ... like the speed of light and the gravitational constant are just scaling factors and so varying them shouldn't lead to quantum ...


20200211: Are Axions Dark Matter?
 04:33: ... added and the strength of those terms is governed by a new fundamental constant  theta. It’s tricky to describe what theta actually signifies  in fact ...
 05:16: ... why doesn’t it? One possible explanation is that this theta value  the constant in front of the CP violating terms  is just equal to zero. That would ...
 08:58: ... in reasonable quantities in the core of the sun. There, Xrays are constantly bouncing off electrons and protons in the presence of strong ...


20200203: Are there Infinite Versions of You?
 07:19: The constants of nature or the energy of the vacuum may well be different between regions.
 12:56: That's because objects in orbit are all moving, so the curvature of the background spacetime is constantly changing.


20200113: How To Capture Black Holes
 12:49: ... is trying to explain the apparent fine tuning of the fundamental constants, not the origin of everything. Ideas like cosmological natural selection ...
 13:26: ... hole is absorbed by another black hole? Do the universes collide? Do the constants average out? The answer to this is ... no one has any idea. The ...


20191217: Do Black Holes Create New Universes?
 00:30: Why, for example, are the fundamental constants  like the mass of the electron or the strength of the forces  just right for the emergence of life?
 00:50: ... there are countless universes with different fundamental constants, then it’s not surprising that a few exist with the right numbers for ...
 02:10: ... in their formation the fundamental constants of the daughter universes are shifted slightly and randomly from their ...
 04:02: ... on the procreating black hole idea by suggesting that the fundamental constants of these new universes could be different to their ...
 04:14: ... seems plausible  if fundamental constants can change at all then surely it’s in the highest possible energy ...
 04:34: ... idea, Smolin added one thing: what if, when universes reproduces, the constants aren’t randomly reconfigured but rather change only slightly  analogous ...
 05:24: ... given universe may not be totally optimal because its constants varied randomly from its parent  in the same way that any given living ...
 05:36: ... there’s a prediction: the fundamental constants that define black hole production should be close to optimal in a given ...
 08:09: ... are no doubt different regions in the landscape of possible fundamental constants where different types of black hole are ...
 10:44: ... natural selection is meant to explain the fine tuning in the fundamental constants, which appear to be either set by design or by extreme ...
 13:40: Please email us with the configuration of fundamental constants you’d prefer and we’ll get it right out to you.


20191209: The Doomsday Argument
 01:38: In 1987, physicist Steven Weinberg used this form of anthropic reasoning to estimate the value of the cosmological constant.
 01:48: ... a quick refresher: the cosmological constant defines the amount of dark energy, which is the stuff causing the ...
 01:57: ... from string theory to eternal inflation predict that the cosmological constant could take on different values in different universes, and its value ...
 02:18: Getting a low cosmological constant is extremely unlikely according to these pictures.
 02:33: ... perhaps we’re just in one of the lucky universes with a low cosmological constant because where else could we ...
 02:49: ... the assumption that lower cosmological constants were less likely than higher ones, Steven Weinberg reasoned that our ...
 03:31: ... refined his estimate of the cosmological constant to be the value that most astronomers across the multiverse would ...
 04:49: This sort of reasoning seems useful  it enabled a decent guess at the cosmological constant.
 08:39: ... Steven Weinberg’s case the question was “what sort of cosmological constant is the typical astronomer likely to observe  so reference class was an ...
 11:20: ... can lead to powerful predictions, like the value of the cosmological constant, it can lead to dubious but worrying predictions like the doomsday ...


20191202: Is The Universe Finite?
 01:38: ... flat, and is dominated by the influences of dark matter and a constant density of dark ...
 02:19: And that's even accounting for accelerating effect of a constant dark energy.
 13:58: ... a very clear one: Stephen Weinberg's prediction of the cosmological constant years before dark energy was ever ...
 15:40: ... Well it would be one whose particular configuration of fundamental constants gives you a universe similar in some respect to lots of other ...
 15:52: ... massively exponentially accelerating universe because the cosmological constant in most universes seems likely to be a lot higher than ...


20191118: Can You Observe a Typical Universe?
 03:01: That means the fundamental constants and initial conditions of the universe must be just right to allow nice habitable planets to form.
 03:31: ... when you add the fact that our universe seems to have fundamental constants and initial conditions that seem extremely finetuned for the eventual ...
 04:21: ... all, it doesn’t tell us WHY the fundamental constants take on the values that they do  or why they may vary between ...
 14:08: ... week we talked about how the constants of nature seem to be fine tuned for life in our universe  and how this ...
 14:21: ... different to ourselves, that could potentially exist if the fundamental constants were ...
 14:36: Well, actually, fine tuning arguments for the fundamental constants for the most part take that into account.
 15:09: Much of the parameter space that the constants of nature could have taken eliminate one or more of these factors.
 15:26: ... I missed one possibility  perhaps the dials defining the fundamental constants were neither randomly set nor deliberately ...
 15:59: ... you only one universe with an unavoidable combination of fundamental constants that was completely devoid of ...
 16:57: ... may be telling us something about how the constants of nature get set  it may be improbable to get those constants ...
 17:41: ... has an idea for a physics problem: iterate through the settings of the constants of nature and figure out the map of possible setting that support ...
 17:53: In other words, find all possible combinations of constants that can produce observers.


20191111: Does Life Need a Multiverse to Exist?
 00:35: Those equations always include one or more fundamental constants  simple numbers that set the scale for the equation.
 00:43: We can’t determine the values of these constants from pure theory  we have to measure them in the real universe.
 00:50: ... are things like the speed of light, the Planck constant, the masses of the elementary particles, and the constants defining the ...
 01:02: ... of particle physics, there are something like 20 independent fundamental constants of ...
 01:44: ... the constants defining our universe were different  a tiny bit different in some ...
 07:37: ... strengths of the fundamental forces are set by the socalled coupling constants  for example, the fine structure constant for electromagnetism and the ...
 08:37: But an even more finelytuned parameter appears to be the cosmological constant.
 11:13: Can we justify the idea of a multiverse with changing fundamental constants?
 11:24: ... theory of everything suggests that the values of the fundamental constants, including the vacuum energy, are set by the particular configuration of ...
 11:47: And there are other proposals for how the fundamental constants might vary over space or between universes.
 12:04: ... in a larger exponentially expanding spacetime, and in each bubble the constants of nature  and especially the vacuum energy  taking on different ...
 12:21: ... holes form, with each new universe having slightly different fundamental constants to its ...
 15:08: ... different types of complexity and even life by tweaking the fundamental constants in different ways, but there seem to be way WAY more combinations of ...


20191015: Loop Quantum Gravity Explained
 16:40: The constant of proportionality can be thought of as the tensile strength of space  the resistance to stretching.
 16:51: And that constant is very, very small  2 by 10^43.


20190930: How Many Universes Are There?
 01:14: ... exponentially due to the vacuum of space itself having a large and constant energy ...
 05:53: For example the cosmological constant – the strength of dark energy – could be different.
 06:51: ... bubble universes that at least some will have a low enough cosmological constant for life to ...
 07:54: Each different configuration results in a different family of particles and also a different cosmological constant.
 08:32: As well as a decent cosmological constant.


20190916: Could We Terraform Mars?
 14:48: Now, without a real atmosphere, space radiation is gonna be a problem for our worldhouse, as is the constant bombardment of micrometeors.
 16:37: Give such a field a constant energy density and you get exponential expansion.


20190903: Is Earth's Magnetic Field Reversing?
 00:46: Now, that’s helpful, because Earth is constantly bombarded by very fast moving charged particles, especially coming from the Sun.


20190819: What Happened Before the Big Bang?
 03:03: These are ephemeral vibrations in the field that are constantly tugging at the field as the field tugs at them.
 04:57: ... would still give us our near constant energy density needed to power inflation and then, as the roll sped up ...


20190806: What Caused the Big Bang?
 02:54: Anything that causes the fabric of space itself to have energy  anything that has a constant energy density pushes rather than pulls.
 03:23: ... the upshot is that if the vacuum of space has a constant energy density, then Einstein's equations end up having a term that we ...
 07:06: We would call this a false vacuum and it gives us exactly the constant vacuum energy density needed for inflation.
 07:59: ... at a constant very high energy density, inflation takes hold; the exponential nature ...


20190403: The Edge of an Infinite Universe
 05:49: ... horizontalish contours are our old time ticks  moments of constant time across the universe, while the verticalish lines are set locations ...


20190328: Could the Universe End by Tearing Apart Every Atom?
 00:25: ... the observed acceleration is for the most part nicely described with a constant density of dark energy the same amount of this stuff in every block of ...
 04:25: ... let's add dark energy in the form of a cosmological constant it usually hangs out outside the brackets because it's emo, but we can ...
 04:32: ... density does not go down, the basic definition of the cosmological constant. So now the pressure term is A, negative and B because of this factor of ...
 06:20: ... that's the case where the density doesn't just stay constant as the universe expands, but it actually increases. The result would be ...
 11:35: ... order. But more likely is that W is exactly 1, meaning dark energy is constant for three reasons: first, it seems too much of a coincidence that it ...
 11:54: ... there's a plausible physical explanation for a constant dark energy that the vacuum has a set amount of energy per volume. There ...


20190320: Is Dark Energy Getting Stronger?
 00:55: It hints that the cosmological constant may not be so constant after all.
 01:59: ... can this accelerating expansion is what you expect if empty space has a constant energy density – so that more space means more dark ...
 02:13: Mathematically we represent a constant vacuum energy with Einstein’s cosmological constant – or Lambda.
 02:51: ... textbooks, this type of cold dark matter sits alongside the cosmological constant as our best description of how the universe behaves on the largest ...
 03:02: Constant dark energy, cold dark matter – or the LambdaCDM model.
 05:32: Perhaps the cosmological constant is not so constant, or dark matter is not so cold after all.
 10:52: And that dashed line – that reflects the expansion history expected in a universe with constant dark energy – a LambdaCDM, concordance universe.
 11:22: ... of the expansion history of the universe in which dark energy is NOT constant, but instead is getting stronger as the universe ...
 11:47: Are concordance and the cosmological constant dead?
 14:13: ... model ends up reigning supreme– even if dark energy proves to be constant after all – which I suspect it will – we’ll have a new, independent ...


20190220: Secrets of the Cosmic Microwave Background
 14:23: ... is that the authors of that paper use a different value for the Hubble constant See, the quoted distance is the comoving distance It's the size the ...


20190207: Sound Waves from the Beginning of Time
 01:04: ... talked about one of those properties in a recent episode, The Hubble constant, and about a growing conflict in its measured value, which hints at ...
 02:14: And scatter they did, constantly.
 12:20: They also confirm the dark energy behaves just as is predicted by Einsteins cosmological constant.


20190124: The Crisis in Cosmology
 00:02: The search for a single number, the Hubble constant,...
 01:12: We encapsulate the expansion of the universe with a single number, called the Hubble constant.
 02:05: ...used to measure this fundamental parameter, the Hubble constant,...
 02:10: But before we get to that, let's talk about the great quest to measure the Hubble constant.
 02:39: If the Hubble constant were, say, 75 km per second per megaparsec,...
 02:51: Historically, measurement of the Hubble constant...
 04:15: ...and the precise measurement of the Hubble constant...
 04:59: ...astronomers were using these supernovae to better nail down the Hubble constant.
 05:44: Recent teams have now narrowed down the Hubble constant to 73.5 ± 1,7...
 07:54: So,... how can the CMB tell us the Hubble constant?
 09:09: So, how do you get the Hubble constant, i.e., the current expansion rate, from all of this?
 12:05: Three: Dark energy isn't constant.
 12:08: The current calculations assume that dark energy is described by the cosmological constant,...
 12:26: The answer will depend on whether the more correct measurement of the Hubble constant...


20190109: Are Dark Matter And Dark Energy The Same?
 02:53: But here’s the punchline: if empty space has a constant, positive energy density then it also has a negative pressure.
 03:27: An important part of this is that the energy density of dark energy is constant, so it doesn’t dilute as the universe expands.
 03:34: In Einstein’s equations and the Friedmann equations, that constant energy density is represented by the cosmological constant, or Lambda.
 07:12: To fix this, Farnes proposes that these negative masses are constantly created as the universe expands.
 07:20: That keeps the density of negative masses constant, even as the density of positive masses falls.
 07:26: The result is a very diffuse negative mass fluid that fills the universe and constantly replenishes itself.
 07:49: So, you remember I said that a constant POSITIVE energy density can be expressed as a cosmological constant?
 08:02: Well a constant NEGATIVE energy density – like the one proposed by Farnes, gives a negative cosmological constant.
 08:18: ... the whole cosmos, this negative mass fluid – as a negative cosmological constant – has the same competing effects as regular dark energy, but in the ...
 08:50: ... Farnes acknowledges that his proposal gives a negative cosmological constant that ultimately decelerates, but there’s some contradiction because he ...
 09:06: And yet a negative cosmological constant gives you an extremely different universe.
 09:15: ...  to correctly conclude that a universe with a negative cosmological constant should have a sinusoidal scale ...
 09:43: The negative cosmological constant is the source of that slowdown and for the subsequent accelerating collapse.
 10:16: Does a universe with a constant negative energy density fit the observations?
 10:48: ... a negative cosmological constant and this sinusoidal expansion, any slowdown happens near the turnaround ...
 11:00: ... first straight part in the rise in the sine curve, which is almost a constant expansion ...
 11:19: We already know that a constant expansion rate happens to give a similar age to the standard dark energy age.
 11:25: But a constant or nearconstant expansion rate definitely does not fit the supernova data.


20181206: Did Life on Earth Come from Space?
 00:37: ... be ejected from the solar system this is Radio panspermia stars may be constantly spraying their germy life through the galaxies in some respects it ...


20181031: Are Virtual Particles A New Layer of Reality?
 10:19: It has a constant zero point energy.
 12:31: ... law without an artifact of that quantum nature namely, the Planck constant. ...


20180912: How Much Information is in the Universe?
 14:27: ... used for radioactive elements, but can be used for anything that has a constant probability of decaying in a given amount of ...
 14:43: The actual amount of time it takes to decay is random, and there's a constant probability of it happening at every set interval.


20180905: The Black Hole Entropy Enigma
 06:56: Do anything to black holes and their total surface area can only grow or stay constant.
 07:50: So entropy can be defined as the information hidden in a system's macroscopic configuration times the Boltzmann constant.
 08:37: ... just multiply that information content by the Boltzmann constant and you have the entropy of a black hole, which is going to be directly ...
 09:36: He got an expression almost identical to Bekenstein's with just a slightly different constant of proportionality.


20180815: Quantum Theory's Most Incredible Prediction
 04:42: The fine structure constant is named after this effect.
 04:45: And we talked about this fundamental constant in an earlier episode.
 10:45: One way to do it is to watch the way electrons process in the constant magnetic field of a cyclotron, a type of particle accelerator.
 11:20: ... calculations to a value for G, you also need to know the fine structure constant that I mentioned ...
 11:32: This is the fundamental constant governing the strength of the electromagnetic interaction of charged particles.
 11:41: So it's really the relationship between the electron magnetic moment and the fine structure constant that we're verifying.


20180801: How Close To The Sun Can Humanity Get?
 01:22: Magnetic storms driving a constant stream of energy and potentially, destructive particles.
 03:12: We already monitor it constantly with groundbased telescopes and spacecraft orbiting the earth or orbiting the sun at a safe distance.


20180725: Reversing Entropy with Maxwell's Demon
 06:26: ... violate the second law of thermodynamics, which demands entropy remain constant or increase, unless energy is exchanged with the outside ...
 10:30: Just multiply by the Boltzmann constant to get the latter.


20180718: The Misunderstood Nature of Entropy
 03:17: ... you can hope for is that the separation of energy and the entropy remain constant. ...
 07:47: ... microstates consistent with the current macrostate times the Boltzmann constant. ...


20180711: Quantum Invariance & The Origin of The Standard Model
 00:33: Our laws of physics are equations of motion tuned by the fundamental constants.
 01:24: An example would be a ball rolling down a hill under a constant gravitational acceleration.
 03:56: These components oscillate in sync with each other, but they're offset, shifted in phase by a constant amount.


20180516: Noether's Theorem and The Symmetries of Reality
 03:11: For example, moving along a perfectly flat road, the downward force of gravity stays constant.


20180502: The Star at the End of Time
 07:57: ... 15% of the Sun's mass, are predicted to enter a period of relatively constant brightness right at the ends of their ...


20180411: The Physics of Life (ft. It's Okay to be Smart & PBS Eons!)
 03:20: ... the second law of thermodynamics entropy appears to either stay constant or ...


20180404: The Unruh Effect
 01:45: For an object with a constant velocity, an inertial object, these world lines are just straight lines, and the slope gives their velocity.
 03:13: That's the world line of an observer undergoing constant acceleration.
 03:33: They fire their rockets and begin a constant acceleration in the opposite direction.
 03:42: Just before they reach my spacetime location, that constant acceleration brings them to a halt, and they start moving back in the opposite direction.
 03:57: That constant acceleration world line traces out a hyperbola, and it has a very interesting property.
 04:28: In reality, eternal constant acceleration would take infinite energy.
 05:06: ... named after the coordinate system we use to describe a constantly accelerating observer in special relativity, Rindler coordinates, ...
 05:20: The Rindler horizon flows at a fixed distance behind a constantly accelerating observer.


20180228: The Trebuchet Challenge
 01:43: ... the same path, the quantity half mass times velocity squared has to be constant. ...
 02:14: ... and potential energy, or motion and potential for motion, remains constant, and not just for one particle, but for any system of any number of ...


20180214: What is Energy?
 02:47: ... like this ball, would gain were it to fall from a given height and a constant ...


20180117: Horizon Radiation
 00:46: And for two observers with very different, but constant speeds inertial observers, the vacuum itself should appear the same.
 03:33: There's no conflict for constant speed inertial observers.


20171213: The Origin of 'Oumuamua, Our First Interstellar Visitor
 00:36: ... survey telescope and rapid response system, a group of telescopes that constantly monitors the sky for moving or variable objects like asteroids or ...
 10:47: But photons have constant speed and no mass.


20171129: Citizen Science + ZeroPoint Challenge Answer
 07:49: The frequency of a photon with the Planck energy is the Planck energy divided by the Planck constant, or an insane 3 by 10 to the power of 42 hertz.
 08:07: There are a bunch of constants in the cutoff frequency vacuum energy relation, but they cancel out.


20171102: The Vacuum Catastrophe
 01:55: ... the vacuum state of any fuel oscillation must be half of the tiny Planck constant times the frequency of that ...


20171004: When Quasars Collide STJC
 10:52: Last week, we talked about the intriguing possibility that the fundamental constants of nature are changing.
 11:00: Nevermind asks whether the fundamental constants are connected to each other.
 11:06: The standard model of particle physics contains 26 independent parameters, things like the coupling constants and the masses of each particle type.
 11:29: In this theory, the value of some constants may prove to be tied to the values of other constants.
 11:35: A few of you took issue with my suggestion that changing fundamental constants help with the finetuning problem.
 11:41: ... principle solves the problem without even changing the fundamental constants. ...
 11:50: ... has the same laws of physics, including the same fundamental constants. ...


20170928: Are the Fundamental Constants Changing?
 00:20: There is a hint of evidence that the fundamental constants that govern our universe may evolve over time, and even from one location to another.
 00:43: Those relationships are often expressed as equations, but they're also governed by the constants within those equations.
 01:00: ... the standard model also depends on a set of constants that cannot be predicted by that model, only measured things like the ...
 01:14: Why the fundamental constants take the values they do is a very deep and unanswered question.
 01:33: They predict that the fundamental constants may not be constant at all, and instead, may vary over time and space.
 01:46: ... because there's a hint of evidence that at least one fundamental constant is, in fact, ...
 01:56: To measure changes in a fundamental constant, we first need to choose the right constant.
 03:05: In fact, it may be impossible to interpret changes in any physical constant that has units.
 03:11: The dimensions behind, say, Newton's gravitational constant or the mass of the electron all have arbitrary human definitions.
 03:20: ... be confident, though we've seen a change in a fundamental constant, way to study a dimensionless constant one that has no units, and ...
 03:33: Perhaps the most promising example is the fine structure constant.
 03:50: We use the Greek letter Alpha to represent the fine structure constant.
 04:18: ... on the fine grain structure of atomic energy levels, which is where the constant gets its ...
 06:20: Well, the magnitude of this wavelength split depends very strongly on the fine structure constant.
 08:43: And there are many other potential systematic errors the could masquerade as a change in the fine structure constant.
 09:32: If the fine structure constant is changing, then it's not changing by very much.
 09:57: ... for the appearance of life are quite sensitive to some fundamental constants, Alpha ...
 10:25: ... if the fundamental constants vary from place to place, then it's not surprising that we find ...
 10:38: ... are also looking into the variation of other dimensionless constants, such as the proton electron mass ratio, and the more obscure proton ...
 11:04: We may one day find that our sacred laws of physics and their underlying constants aren't so constant after all beyond our little patch of space time.
 11:45: ... of Everything." Professor Lincoln even discusses our ideas about why the constants of nature take on the values they ...
 12:34: Richard, thank you, and may your own fundamental constants remain stable and forever within a range that supports life as we know it.


20170830: White Holes
 05:04: Also, lines of constant distance and time curve, so that light paths always travel on 45 degree paths.
 05:33: In our weird Penrose coordinates, this represents a constant distance from the center of the black hole.


20170824: First Detection of Life
 05:26: Water has a high dielectric constant, which means it's good at storing electrical energy.


20170810: The OneElectron Universe
 11:13: OKFFF1 comments that data flow must have a constant velocity and not be accelerating.


20170719: The Real Star Wars
 16:57: The probability of that interaction is governed by the coupling constant between those fields.
 17:02: So the electric charge, which in turn depends on the fine structure constant.
 17:07: In fact, the probability amplitude added at each vertex is proportional to the square root of the fine structure constant.
 17:20: So that's the square root of 1/137 squared, which is just the fine structure constant, which is close to 1%.
 17:40: Onlynamelefthere thinks our videos "are good and stuff, but will unsubscribe if we "set the fine structure constant to 1/100" once more.
 17:53: You guys think you're so cool measuring the fine structure constant to better than 1 part in a billion.


20170712: Solving the Impossible in Quantum Field Theory
 08:36: This latter case can be thought of as the electron causing a constant disturbance in EM field.
 08:41: Electrons are constantly interacting with virtual photons.


20170628: The First Quantum Field Theory
 10:01: It predicts the relative value of the fine structure constant to a precision of one part in a billion.


20170621: AntiMatter and Quantum Relativity
 05:55: It contains the marks of both quantum mechanics, in the Planck constant, and relativity, in the speed of light.


20170517: Martian Evolution
 08:06: The human immune system is constantly being exercised by exposure to Earth's biosphere, which contains countless bacteria and viruses.


20170426: 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.


20170329: How Time Becomes Space Inside a Black Hole
 06:33: It deals with the extreme stretching of space and time by compact defined lines of constant space or time close to its boundaries.
 06:44: But an important thing to remember is that the lines of constant space and time are curved so that light cones remain upright.


20170322: Superluminal Time Travel + Time Warp Challenge Answer
 01:54: ... in a state of now, and that all points move forward in time at a constant rate for all observers, governed by one global ...
 03:13: These are contours of constant spacetime interval.


20170315: Time Crystals!
 01:30: Time crystals repeat some internal state with constant separations in time.


20170308: The Race to a Habitable Exoplanet  Time Warp Challenge
 00:58: We talked about how the constant or invariant nature of the speed of light governs that transformation.
 01:35: ... we represent lines of constant spacetime interval with respect to x and to equal zero as contours, then ...


20170215: Telescopes of Tomorrow
 05:31: ... of the best astronomical observing in the world, even that air is in constant ...


20170202: 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.
 05:06: They see themselves as stationary, so their time axis is just their own constant velocity world line.


20170119: The Phantom Singularity
 06:30: In fact, it's 2 times the gravitational constant times the mass.


20170111: The EM Drive: Fact or Fantasy?
 04:14: It's the same tool that Henry Cavendish used to first measure the teensy tiny gravitational constant over 200 years ago.


20170104: How to See Black Holes + Kugelblitz Challenge Answer
 06:13: You can think of the verticalish lines as representing points in space that are a constant distance from our center point.


20161214: Escape The Kugelblitz Challenge
 02:47: The shape of spacetime outside the horizon warps to make this diagonal line, a line of constant radius, the radius of the new black hole.


20161208: What Happens at the Event Horizon?
 04:25: It also curves the lines of constant time and constant space in what we call a conformal transformation so that light always follows a 45 degree path.
 06:16: Weirdly, the lines of constant position and constant time switch.


20161130: Pilot Wave Theory and Quantum Realism
 00:55: ... reality, cats are both alive and dead, or even that the universe is constantly splitting into infinite alternate ...


20161109: Did Dark Energy Just Disappear?
 01:54: They suggest the universe may be just expanding at a constant rate: never speeding up, but also not slowing down.
 04:06: The new study claims a 3sigma confidence that there is a positive cosmological constant.
 04:14: ... quick aside: the cosmological constant, written as lambda, is the thing you add to Einstein's equations of ...
 04:26: If the cosmological constant exists, and is larger than zero, then dark energy is a real thing.
 04:32: ... so 3sigma confidence in a positive cosmological constant basically means this: if you repeated this experiment many, many times, ...
 05:44: ... claimed a significance of 3sigma or lower for a positive cosmological constant based on that early supernova data ...


20160803: Can We Survive the Destruction of the Earth? ft. Neal Stephenson
 07:21: Do we trust them to keep a constant watch on the heavens, on global volcanic activity, and on potential threats from the biosphere?


20160720: The Future of Gravitational Waves
 06:16: To do this, you needed to assume that the alpha particle bounces back and forth between the walls of the nucleus with a constant velocity.


20160622: Planck's Constant and The Origin of Quantum Mechanics
 00:03: ... episode is supported by "The Great Courses Plus." The Planck constant defines the size scale at which the familiar physics of our macroscopic ...
 00:23: In fact, you can see the effect of this quantum behavior and even measure the Planck constant just by observing the color of sunlight.
 01:45: The tiny Planck constant, at 6.63 by 10 to the minus 34 joule seconds, sets the scale of this quantum blurriness.
 02:04: In fact, the Planck constant appears in essentially all equations that describe quantum phenomena.
 02:36: It may define the scale of quantum reality, but the influence of the Planck constant can be seen even on our scale.
 02:49: If the Planck constant were 25% smaller, the sun would be violet, all else being equal.
 07:48: That number became the Planck constant.
 08:29: He expected his new constant to turn out to be 0, which would mean no interval between energy states, no quantization, no minimum energy.
 08:40: In that case, the Planck constant would have canceled out in the final equation, but it didn't.
 08:47: The Planck constant is firmly entrenched in the Planck blackbody law.
 08:55: Now the actual value of the Planck constant still had to be measured.
 08:59: ... the blackbody spectrum, it was possible to do this just by varying the constant until the Planck law matched the observed ...
 09:10: ... the Planck law and an object's temperature, you can calculate the Planck constant just by finding the brightest part of an object's heat glow, for ...
 09:52: ... energy equal to the now familiar frequency of the wave times the Planck constant. ...
 10:27: And that little number that Max Planck came up with in his moment of desperation the Planck constant remains at the heart of all things quantum.
 10:38: ... defining the shape of the blackbody spectrum, the Planck constant can be read in the color of the sun and the stars, in the brightness of ...
 10:47: And combined with a small handful of other fundamental constants, it governs the behavior of everything in this space time.


20160615: The Strange Universe of Gravitational Lensing
 05:57: ... distance measurements have allowed us to measure the Hubble Constant, which tells us the rate of expansion of the universe, independently ...


20160608: New Fundamental Particle Discovered?? + Challenge Winners!
 13:17: Or should we take this as evidence that our simple idea of a constant dark energy density is wrong?


20160601: Is Quantum Tunneling Faster than Light?
 02:33: In fact, it's the minuscule Planck constant divided by momentum.


20160518: Antigravity and the True Nature of Dark Energy
 01:24: This dark energy is described by the cosmological constant in the equations of general relativity.
 01:48: Today, we're going to talk about the simplest interpretation of dark energy, one where the cosmological constant really is constant.
 02:03: A constant cosmological constant represents a nonzero energy of empty space, a vacuum energy.
 02:15: It's a constant energy density.
 02:18: OK, the big, weird fact about a constant vacuum energy density is that leads to exponential expansion.
 06:26: This was actually Einstein's motivation for adding the cosmological constant in the first place.
 06:47: The cosmological constant was designed to work in the opposite direction to regular matter and energy.
 07:08: The effect of the cosmological constant is the combined effect of dark energy's own density and pressure.
 09:46: Instead, it comes directly from the fact that the density of dark energy is constant.
 09:53: Let's say I'm holding a volume of the universe that has a constant energy density.
 10:29: As the universe expands, more dark energy is created because its energy density has to stay constant.
 11:01: But both agree that a constant energy density and the resulting negative pressure leads to accelerating expansion.


20160511: The Cosmic Conspiracy of Dark Energy Challenge Question
 02:16: ... derived from those, dark energy is described by a positive cosmological constant. ...
 02:25: If that constant truly stays constant over time, then it represents an energy of the vacuum.
 02:30: Its density stays constant and so the amount of dark energy increases at the same rate as the volume of the universe.
 02:47: At the same time, the total amount of regular matter in any expanding region remains constant.
 03:55: Assuming a constant expansion rate, a constant increase in the scale factor, that means it was only two to three billion years ago.


20160504: Will Starshot's Insterstellar Journey Succeed?
 09:17: Its density stays constant.
 09:54: ... it's really fully described by a constant cosmological constant and so has an unchanging density with time, then ...


20160427: What Does Dark Energy Really Do?
 00:40: And this is only allowed if we introduce a new type of energy represented by the cosmological constant.
 07:10: However, this accelerating expansion can be explained with the same bit of math, the cosmological constant, pointing to the same physics, dark energy.
 07:22: Add the cosmological constant to the first Friedmann equation, and we reconcile the left and the right side.
 07:28: But we also see that the constant nature of this term means that the larger the universe, the more of this stuff there is.
 07:36: This lets us interpret the cosmological constant as representing a sort of vacuum energy, a property of space itself.
 07:48: But why should a constant vacuum energy cause the universe to accelerate?
 08:16: Expansion will only depend on the cosmological constant.
 08:21: So does that mean the expansion will become constant?
 08:25: See, it's not the expansion rate the Adot that's constant in this equation.
 08:31: Adot over A will become a constant.
 08:41: The Hubble Constant is just the Hubble Parameter for the present day.
 08:50: But with a positive cosmological constant, the universe will eventually have a constant Hubble Parameter.
 08:56: And so we'll have a constant doubling time.
 09:23: If the cosmological constant stays constant, we can expect an exponential growth to continue.
 09:30: But will it stay constant?
 11:45: ... verified in so many other ways, and the addition of the cosmological constant works so well to describe the discrepancy, it's strongly suggested this ...
 12:03: As we saw today, the cosmological constant solves two measure discrepancies.
 12:07: So at some level, it's right, even if we don't know what causes it or whether it's truly constant.


20160420: Why the Universe Needs Dark Energy
 06:34: We missed the cosmological constants.
 06:50: ... we derive the first Friedmann equation with the cosmological constant included that's the lambda symbol, here we end up with this little ...
 07:00: ... the cosmological constant is positive, this works on the side of the density term to help bring ...
 07:31: The expression "cosmological constant" is a clue.
 07:34: This term, as we commonly interpret it, is constant.
 07:43: The weird stuff described by the cosmological constant doesn't do that.
 07:48: Its density stays constant.
 08:39: Soon, we'll get to the second and most compelling piece of evidence for dark energy and for the cosmological constant.


20160413: Will the Universe Expand Forever?
 07:18: The expansion rate now is what we call the "Hubble constant." It's around 70 kilometers per second per megaparsec.


20160406: We Are Star Stuff
 10:58: ... negatively curved, I should say that the curvature of space at a single, constant moment in time has to be one of these ...
 11:10: So constant time spatial curvature, which is different to the curvature of spacetime.


20160323: How Cosmic Inflation Flattened the Universe
 06:48: Actually, Einstein came up with the exact mathematical description that we need an antigravity term called the cosmological constant.
 07:10: When it was later discovered that the universe is indeed expanding, Einstein retracted his constant.
 07:30: The cosmological constant represents something that can happen to our spacetime.
 07:38: The cosmological constant adds some energetic stuff to empty space.
 08:15: ... its own expansion and will do so if the vacuum contains a ubiquitous constant energy ...


20160316: Why is the Earth Round and the Milky Way Flat?
 02:34: ... a space thing of any shape and there's nothing else around, a surface of constant gravitational field is a ...


20160203: Will Mars or Venus Kill You First?
 01:35: ... lack of a strong magnetosphere has allowed the solar wind, the constant stream of energetic particles from the sun, to whittle away at Mars' ...
 05:21: But that low constant solar wind is nothing compared to a coronal mass ejection.
 10:38: Living in a state of constant existential awe gives you a migraine.


20160127: The Origin of Matter and Time
 02:11: Constant speed equals constant change in position x with time t.
 04:08: A second photon clock with a constant speed with respect to the first, travels a steeper time light path.
 05:01: The whole space time diagram can be transformed to give the second clock's world line a constant location in space.
 05:48: We can draw that time axis along any constant velocity timelike path, and just Lorentz transform to get a valid perception of space time.
 11:16: And special relativity only describes the relative effects on time and space due to a constant relative motion.


20160113: When Time Breaks Down
 01:11: ... themselves held in place by protons that are comprised of quarks in constant ...
 06:06: Here, we're talking about something moving at a high but constant speed.


20151216: The Higgs Mechanism Explained
 02:48: Now, that spin constantly flips back and forth.


20151111: Challenge: Can you save Earth from a Killer Asteroid?
 02:05: ... clue for now, you don't need calculus to do this if you assume constant propellant use over the seven years and calculate an average spacecraft ...


20151015: 5 REAL Possibilities for Interstellar Travel
 11:24: ... point, it perhaps becomes more interesting to ask why other fundamental constants of nature have the values that they do compared to the speed of ...
 11:33: ... that said, the relative units of the fundamental constants, the speed of light, the strength of the fundamental forces, et cetera, ...


20151007: The Speed of Light is NOT About Light
 00:32: The universe doesn't arrange itself to keep the speed of light constant.
 00:41: This universal constant is, perhaps, more accurately, the speed of causality.
 05:26: Now, you can get to this transformation the way Lorentz and Einstein did by requiring a constant speed of light.
 08:14: That value has to be a combination of the fundamental constants of Maxwell's equations.


20150827: Watch THIS! (New Host + Challenge Winners)
 00:41: ... a spring, you can work out an expression based on those proportionality constants for how much time it takes to do a complete ...


20150729: General Relativity & Curved Spacetime Explained!
 01:54: ... the world lines of other inertial observers are straight, indicating constant spatial ...


20150722: SPECIAL ANNOUNCEMENT + Flat Spacetime Geometry Comments
 02:36: ... the episode are the same frame so we would ordinarily see moving with a constant threedimensional velocity through ...
 02:48: Inertial observers will see each other dynamically, moving with a constant threedimensional velocity.
 02:54: But does that mean that inertial observers are really moving with a constant threedimensional velocity?
 03:05: ... a world without gravity, there's a way to discern who's really moving at constant threedimensional velocity, sort of which is those observers whose ...
 04:41: They're moving at constant spatial velocity.


20150715: Can You Trust Your Eyes in Spacetime?
 02:42: All right, now, some weirdo in a red shirt carrying his own clock and xaxis approaches me from the left at constant speed.
 03:32: And so, he moves at the same constant speed that the red guy does.
 08:37: ... a spacetime speed, then the world line of every inertial observer is a constantspeed straight ...
 08:49: And accelerated observer's world lines are constantspeed nonstraight lines.


20150702: Can a Circle Be a Straight Line?
 00:16: ... pulled by a gravitational force, they're simply following straight line constant speed paths in a curved ...
 01:02: ... world is a curved spacetime, then the familiar meanings of terms like a constant velocity straight line and acceleration will become ...


20150624: The Calendar, Australia & White Christmas
 02:33: So the location in space of January 1 is constantly moving.


20150603: Is Gravity An Illusion?
 01:25: ... you whether a frame of reference is really at rest or really moving at constant velocity because that distinction is meaningless and simply a matter ...
 09:00: ... the world is a nonEuclidean and curved spacetime, then straight line at constant speed doesn't mean what you think it means and it turns out that ...
 09:30: And in that curved spacetime, the orbit of the ISS is a constantspeed straight line.
 09:38: Constantspeed straight line.


20150527: Habitable Exoplanets Debunked!
 10:09: ... to modify the definition of the SI kilogram in terms of fundamental constants of nature, like Planck's constant and the speed of ...


20150429: What's the Most Realistic Artificial Gravity in SciFi?
 04:57: ... Coriolis effect under the rug, especially the part where Poole would be constantly falling down while ...


20150325: Cosmic Microwave Background Explained
 00:29: ... types of interference, no matter how you orient your dish, there's this constant underlying microwave band static that's just always there in the ...
 03:43: So at this moment, it was as if flash bulbs were constantly going off everywhere in space, but the light was being snuffed out by a fog.
