
20221109: What If Humanity Is Among The First Spacefaring Civilizations?
 17:23: ... in which the wavefunction appears to change everywhere at the instant a measurement is made, in apparent violation of relativity and the speed of light ...
 18:13: Benjamin Shropshire asks if anyone has ruled out hidden influences traveling from the measurement back in time to the creation of the entangled state.
 19:08: ... asks if there’s a problem using a random number generator to decide measurement direction, considering that true randomness is ...
 19:36: ... require a pretty complicated conspiracy of influences connecting every measurement device with every potential measurement subject, and I’ve never heard a ...


20221026: Why Did Quantum Entanglement Win the Nobel Prize in Physics?
 02:13: Each ball is in a superposition state of maybe blackmaybe white until a measurement is made.
 04:54: ... if those properties really are decided at the moment of measurement. ...
 07:09: ... quantum mechanics says that those polarizations are undefined until measurement, when they will always turn out to be opposite to each ...
 07:56: ... result of a quantum measurement depends on how you make the measurement  in the case of this ...
 08:08: Bell’s theorem assumes the choice of measurement is completely free and independent of the particle creation process.
 08:35: ... the photons might carry hidden information about the eventual measurement direction the whole time and sort of conspire to look like standard ...
 08:47: To close this loophole it would be necessary to somehow set the measurement direction after the photons were produced.
 09:22: ... order to change the measurement direction of a polarizer you have to rotate it, but it’s kinda hard ...
 09:33: Aspect found a way to randomize measurement direction without moving the polarizers at all. The trick was to use a type of transducer.
 10:46: The first I already mentioned: what if the choice of measurement is not independent of the creation of the entangled particles?
 11:16: ... but also with the random number generator or the physicist choosing the measurement direction, so ultimately the universe has no choice ...
 16:23: ... we’ll be trying to send actual images rather than simple numerical measurements and status ...


20221012: The REAL Possibility of Mapping Alien Planets!
 01:25: ... repeat this trick with visible light because this requires exact measurement of the arrival time and phase of the electromagnetic ...


20220928: Why Is 1/137 One of the Greatest Unsolved Problems In Physics?
 02:22: ... our measurement apparatus improved, we saw that the single spectral lines were ...
 09:43: The problem is, most of these constants require you to choose units of measurement.


20220914: Could the Higgs Boson Lead Us to Dark Matter?
 12:38: The error bars on this measurement are still large, and so we need to watch more Higgs bosons decay.


20220817: What If Dark Energy is a New Quantum Field?
 04:47: ... yeah, and it’s pretty much … 1, the default option. Our most precise measurement comes from Planck satellite data, which mapped the cosmic microwave ...
 06:25: ... universe we get a different number. The latter is from Planck satellite measurements of the cosmic microwave background. The current thinking is that one of ...
 13:27: ... fully operational James Webb Space Telescope will help by pushing our measurements of the expansion rate back billions of years from the current supernova ...


20220803: What Happens Inside a Proton?
 16:44: ... defined by your choice of experimental axis at the moment of measurement. You’ll always measure fullyup or fullydown, no matter what ...
 18:44: ... partner then you know what its spin is. However that measurement isn't a passive act  you will have actually forced the ...


20220720: What If We Live in a Superdeterministic Universe?
 02:33: The results of your measurements are plucked from the wavefunction of whatever you’re observing.
 02:39: We say that measurement “collapses” the wavefunction, obliterating all potential results in favor of one actual result.
 03:27: Measurement of one electron would influence the other in a very real way  something Einstein referred to as spooky action at a distance.
 04:02: According to standard quantum mechanics, that spin is undefined until measurement.
 04:06: Upon measurement it will become fixed along the axis of the measurement device.
 04:37: A horizontal measurement will yield a 5050 chance of being left or right for his downpointing electron.
 04:51: ... they’ll notice certain peculiar correlations between their choices of measurement axis and the other’s measured ...
 06:01: The scientists go off and make their own choices for their measurement directions.
 06:10: When the two compare results, they will see correlations between the spin measurements because the original spin directions were correlated.
 06:17: But there’s no correlation between one scientist’s measurement results and the other scientist’s choice of measurement direction.
 09:22: The Bell test results are weird because Bob’s measurements turn out to be inexplicably correlated with Alice’s choices.
 10:02: That’s the statistical independence of the measurements.
 10:24: ... between Alice and Bob’s supposedly free decisions of how they make their measurements, and the states of the measured ...
 11:45: To close the loophole, a Bell test needs to be performed where the choice of measurement direction is truly statistically independent.
 12:08: ... we can at least do a Bell test where the “deciders” and the measurement subjects have past light cones that intersect with each other as far ...
 12:35: ... that light was used in place of a random number generator to decide the measurement orientation in the Bell ...
 13:43: ... lockstep determinism in a way that preserves correlations between measurement subject and ...


20220601: What If Physics IS NOT Describing Reality?
 04:56: ... is the spin up or down relative to the direction of measurement? We ask this question with a Stern Gerlach apparatus, where ...
 05:53: ... information about its spin in that direction. And following that measurement, the leftright alignment of the spin has become defined  after ...
 07:23: ... learn the spin direction of both particles. And in making that measurement, you’ve forced the single bit of spin information in both electrons ...
 08:49: ... from a quantum wavefunction. For example, that the product of the measurement error in a particle’s position and momentum has to be ...


20220427: How the Higgs Mechanism Give Things Mass
 16:02: ...  but that’s for another time. But what about this new measurement of the W boson mass? Mass results from interaction with the Higgs ...


20220420: Does the Universe Create Itself?
 00:59: ... and quantum mechanics. In quantum mechanics, not only does the act of measurement profoundly influence the thing being measured, but it seems we can’t ...
 07:08: ... really does exist in a superposition of all possible states until the measurement is made, and the choice of that measurement can be made after the ...
 07:43: ... a pair of entangled particles  the choice of the direction of the spin measurement seems to have an instantaneous influence on its partner, even if that ...
 12:05: ... time two particles bump together and become entangled we have an act of measurement. If this all seems a little vague and wishy washy, it’s because it is. ...


20220316: What If Charge is NOT Fundamental?
 02:30: ... corresponding to the spin axis being aligned or antialigned with your measurement device, which we’ll call “up” and “down” ...


20220308: Is the Proxima System Our Best Hope For Another Earth?
 08:18: Followup observations in January this year somewhat solidified the measurements of Proxima D.


20220216: Is The Wave Function The Building Block of Reality?
 01:06: ... example when we make a measurement of a particle, the property that we’re measuring seems to be plucked ...
 01:16: We say that the wave function collapses  it appears to shrink to a window whose narrow width is defined by the precision of our measurement.
 05:09: ... different parts of the wave function corresponding to different possible measurement results to evolve independently of each other. Another thing about the ...
 06:53: ... necessarily means bringing lots of particles into the picture  in the measurement device and in your own brain. With enough particles collapse becomes ...
 10:48: ... Experiments are approaching the masses necessary to make such direct measurements, but they’re not quite there ...
 11:50: ... of copper and lead. With such pristine conditions for a highprecision measurement, the scientists in Trieste were able to measure single photons emitted ...


20211210: 2021 End of Year AMA!
 00:02: ... the quantum world sort of makes a decision uh uh in the sense of a measurement being made and say an electron having to choose one position or ...


20211013: New Results in Quantum Tunneling vs. The Speed of Light
 02:52: ... measurement, or upon interaction with another particle, the proton can end up ...
 07:08: ... that wavefunction can’t travel faster than the speed of light, but upon measurement, the particle may appear to be at the leading edge of its wavefunction  ...


20211005: Why Magnetic Monopoles SHOULD Exist
 04:37: ... that the equations of quantum mechanics had a particular symmetry  the measurements they predict are unaltered by changes in one simple property  the phase ...


20210921: How Electron Spin Makes Matter Possible
 08:21: ... never, ever observe Psi  all we can do is map Psi^2 by making multiple measurements. The unobservability of Psi is critical to this whole explanation, so ...


20210818: How Vacuum Decay Would Destroy The Universe
 09:38: ... can determine the shape of the Higgs field with precise measurements of the particles that gain their mass from the Higgs. ...


20210810: How to Communicate Across the Quantum Multiverse
 02:29: ... which says that the wavefunction collapses at the point of measurement, leaving only one reality; or de BroglieBohm pilot wave theory, which ...
 03:30: ... changes over space and time  and so it should completely determine the measurements we can make of that quantum system. But if our observations are 100% ...
 07:14: ... could give a way to explore what happens to the wavefunction after measurement. Does it vanish as Copenhagen demands, or persist as many worlds would ...
 08:08: ... way. You can only detect that the influence happened by comparing the measurement statistics of multiple entangled pairs  and to do that you need to send ...
 09:57: ... call them up or down. In the manyworlds interpretation, by making that measurement you just split the world in two and you split yourself. In one world you ...


20210803: How An Extreme New Star Could Change All Cosmology
 05:39: ... with our measurements for temperature and brightness, we get a radius for Zee of 2140 ...
 11:52: ... there does seem to be a disagreement between the supernova dark energy measurements and the measurements from the cosmic microwave background  again, ...


20210721: How Magnetism Shapes The Universe
 15:28: ... that for every measurement of a spin1/2 state we get 2 worlds, but for every measurement of photon ...


20210713: Where Are The Worlds In Many Worlds?
 04:04: ... measurements appear to be randomly selected based on the current state of the ...
 04:16: We never see the wavefunction  we only see measurements  we pluck our reality from this fantastically complex structure.
 05:22: ...  it instantaneously shrinks from encompassing a huge range of possible measurement outcomes to encompassing only the outcome that was measured  and that ...
 08:14: ... no way to make a perfectly reliable measurement without corrupting the phase of the wavefunction in a way that destroys ...


20210707: Electrons DO NOT Spin
 03:48: ... assume electrons have a maximum possible size given by the best measurements of the day, then their surfaces would have to be moving faster than ...


20210623: How Quantum Entanglement Creates Entropy
 03:45: ... precisely the amount of information we can hope to gain by making a measurement on the system. If all the particles are bunched up in the ...
 05:55: ... information we can get out of the system when we make a measurement. But perhaps the most interesting  von Neumann entropy tells us ...


20210616: Can Space Be Infinitely Divided?
 07:10: ... any further decrease in photon wavelength actually increases your measurement uncertainty due to the warping of space. So this is one way of ...


20210525: What If (Tiny) Black Holes Are Everywhere?
 13:36: ... at how the Heisenberg uncertainty principle can be gamed to improve measurements  in particular in gravitational wave ...


20210519: Breaking The Heisenberg Uncertainty Principle
 00:25: ... is good to to one part in a billion And also pretty recently we have the measurement of gravitational waves by ...
 00:47: ... measurements have become so precise that we’re starting to run up against the ...
 01:05: Today we’re going to see how the uncertainty principle can be hacked to make measurements more precisely than should ever be possible.
 01:36: Exact measurement of its energy means its location in time is blurred.
 02:37: ... which would account for a greater uncertainty in its momentum after the measurement. ...
 02:56: Basically, he thought the uncertainty principle arose as a result of the measurement disturbing the system.
 06:05: This measurement is incredibly sensitive to the path lengths  but that means it’s also sensitive to the phase of the light waves.
 09:56: The use of squeezed light is just one example of how quantum mechanics can be used to increase measurement precision.
 10:17: ... the limit beyond what we thought possible to force ever more certain measurements of this uncertain space ...


20210407: Why the Muon g2 Results Are So Exciting!
 02:22: QED predicts the value for the electrons gfactor that matches experimental measurements to one part in a billion.
 02:44: Starting in 20 years ago, experimental measurements of the Muon gfactor did not agree with the QED calculation.
 06:52: For the electron, the current measurement is precise to one part in a billion.
 09:00: Prior to this experiment, various labs over the past 20 years have refined the Muon gfactor measurement.
 11:10: ... course this was a systematic error, some unknown factor influencing the measurement that is not a new particle, the g2 team worked very hard to rule ...
 11:20: But the only way to be sure is to repeat the measurement with a new independent experiment.


20210323: Zeno's Paradox & The Quantum Zeno Effect
 07:02: ... to the researchers, the laser acts like a measurement  and remember, measurement should be able to freeze quantum arrows and ...
 07:23: In theory, if these “measurements” are fast enough they should stop the wavefunction from evolving.
 08:29: ... physicist Leslie Ballentine argued that it’s not the abstract act of measurement that causes the quantum Zeno effect, but rather it’s a physical ...
 08:43: ... the very foundations of quantum mechanics: what exactly do we mean by a “measurement” and what do we mean by wavefunction ...
 08:54: Let’s start with measurement.
 08:55: ... never possible to perform a measurement without interacting with a system, and that interaction has consequences ...
 09:04: If the measurement interaction is subtle enough then you might hope to gain that info without perturbing the system too much.
 09:21: ... the atom with many, many photons  and that was certainly not a “subtle” measurement. ...
 09:30: ... Washington University claim to have proved that it’s perturbation, not measurement, that causes the quantum Zeno effect by demonstrating that with the right ...
 09:50: Another way to think about measurement is in terms of how much information it extracts from the system.
 09:55: ... idea is that measurement causes wavefunction collapse because it scrambles the delicate ...
 10:52: In the Copenhagen interpretation, only the part of the wavefunction corresponding to the measurement outcome survives.
 12:10: And perhaps some of this is just semantic  for example, how do we really define measurement and interaction?
 13:40: ... clarification, pointing out that that the CMB number isn't actually a "measurement" of the current rate of expansion  which of course it can't be because ...
 14:22: ... therefore be resolved by finding an error in either the CMB or supernova measurements, but also by finding one of the assumptions in the CMB calculation is ...


20210316: The NEW Crisis in Cosmology
 00:22: ... we have two extremely careful, increasingly precise measurements of how fast the universe is expanding which should agree ...
 02:07: ... the redshifts. It depends on a long chain of distance measurements that we call the cosmic distance ladder. First you ...
 02:36: ... distance measurements were based on a method pioneered by Henrietta Swan ...
 03:55: ... With its discovery it suddenly became VERY important to perfect our measurements of the expansion rate  both to confirm dark ...
 06:22: ... a giant space ruler. Ultimately, refining the supernova distance measurements comes down to refining parallax measurements, and ...
 08:03: ... so it was that in 1912 Henrietta Swan Leavitt used parallax measurements of Cepheids in the Milky Way to turn these stars into ...
 10:40: ... time delay in these flickering lenses, we can get a measurement of cosmic distances, and with that a measurement of the expansion ...


20210112: What Happens During a Quantum Jump?
 01:02: That proof required precision measurements that didn’t exist in Schrodinger’s time.
 02:55: ... says that “measurement collapses the wavefunction”, which these days is more often taken to ...
 11:27: It's to do with how strongly the system is coupled to the measurement apparatus.
 11:31: The weaker the measurement, the less likely a true quantum jump is to occur.


20201215: The Supernova At The End of Time
 15:25: ... you CANNOT reverse time in the double slit experiment, because after the measurement of particle position is made, the state of the wavefunction before that ...


20201208: Why Do You Remember The Past But Not The Future?
 03:29: Actually, not really  perfect measurement isn’t really possible, even assuming all the necessary information was still inside the rock.


20201111: Can Free Will be Saved in a Deterministic Universe?
 08:16: ... practice, because unknown random processes are at work, and/or perfect measurement is not possible for any entity that could possibly ...


20201020: Is The Future Predetermined By Quantum Mechanics?
 04:23: ... defined by the equations of quantum mechanics but at the moment of measurement, a single reality is randomly selected from the distribution of possible ...


20200728: What is a Theory of Everything: Livestream
 00:00: ... really nailing down the cosmological constant really doing precision measurements in all different types of lower energy machines right because the ...


20200720: The Boundary Between Black Holes & Neutron Stars
 08:43: ... direct measurements of neutron star masses come from pulsars  cosmic lighthouses that ...


20200708: Does Antimatter Explain Why There's Something Rather Than Nothing?
 08:50: ... the more tests they can conduct on it, and so the more precise their measurements will ...
 10:18: In a recent measurement, ALPHA's been able to test CPT invariance down to 16 parts per billion. So far no evidence of CPT violation.
 10:39: ... in their trap. They expect this to dramatically improve their measurement ...


20200608: Can Viruses Travel Between Planets?
 15:01: ... you need to factor in the Casimir force between them to get an accurate measurement of the gravitational ...


20200527: Does Gravity Require Extra Dimensions?
 08:02: But Mitchell died before he could conduct the experiment, and so Cavendish inherited and improved the device, and actually made the measurement.
 08:55: ... and by reading off the amount of rotation Cavendish made the first measurement of the gravitational ...
 09:42: His measurement remained the most precise for over 100 years.
 09:47: ... the beginning of a grand tradition in physics of making highprecision measurements to learn about the fundamental nature of the ...
 10:33: These incredible advances have led to a modern measurement with 6 digits of precision.
 11:19: The inverse square law seems to hold down to the current limits of our measurements.


20200428: Space Time Livestream: Ask Matt Anything
 00:00: ... not say one word when zero words would do there was also a unit of measurements in in Cambridge for the rate of speech where one Dirac equaled one ...


20200316: How Do Quantum States Manifest In The Classical World?
 03:37: ... spin depends on how you choose to measure it  it depends on your “measurement basis.” And a well defined spin direction in one basis can be expressed ...
 05:32: ... if I measure the spin of one particle  say the electron  my choice of measurement basis defines the spin of the positron. If I measure the electron in the ...
 08:44: ... the atom’s state, which would influence the electron and positron. The measurement hasn't actually happened yet. The wave function hasn't collapsed. Here’s ...
 09:56: ... so our atomic measurement device doesn’t “collapse the wavefunction.” It doesn't settle ...
 10:53: ... this information if you could perfectly measure all particles in your measurement device. But eventually this entanglement cascade reaches the surrounding ...
 11:11: ... this entanglement web. These are properties of the quantum system  measurement bases  whose information is relatively simply reflected throughout the ...
 13:22: ... should say none of this fully solves the measurement problem it only tells us why certain quantum states are observable on ...
 13:47: ... object positions, feline mortality statuses, even the results of quantum measurements  do NOT exist in the underlying quantum objects. Quantum objects remain ...
 17:40: ... interpretation states that only one branch of the wavefunction survives measurement, corresponding to one possible result of that measurement. And the ...


20200303: Does Quantum Immortality Save Schrödinger's Cat?
 00:39: ... same time, to having only one clear observable state at the moment of measurement? ...
 00:51: This is the measurement problem.
 01:01: ... something very important: by itself, decoherence does NOT solve the measurement ...
 01:29: ... branches that we don’t observe somehow vanish at the moment of measurement. ...
 11:51: ... and on quantum decoherence as a better path to understanding the measurement ...


20200224: How Decoherence Splits The Quantum Multiverse
 00:35: ... last week’s episode we started down this rabbit hole exploring the measurement problem  the question of why and where the blurry quantum wavefunction ...
 01:03: The upshot is that more and more physicists think that consciousness  and even measurement  don’t directly cause wavefunction collapse.
 01:52: ... the distribution of possible outcomes if you were to try to make a measurement of that ...
 09:11: Any measurement device must introduce some level of decoherence to the wavefunction before it reaches the screen.
 14:12: Nor is it accepted that decoherence fully explains the measurement problem and wavefunction collapse.


20200218: Does Consciousness Influence Quantum Mechanics?
 01:42: ... tells us that the very act of measurement or observation causes an experiment to settle on a particular result, ...
 03:05: The Copenhagen interpretation states that, prior to measurement, it’s meaningless to talk about a real, physical state for the electron.
 03:12: It exists only as the possible outcome of a future measurement.
 03:16: Prior to measurement, it IS its wavefunction.
 03:20: ... tells us that when we make that measurement the wavefunction “collapses”  it goes from a cloud of possible final ...
 04:46: ... measuring apparatus and the conscious awareness of the result of that measurement. ...
 05:49: We call this open question the Measurement Problem.
 08:02: Wigner and von Neumann weren’t the only ones who questioned the relationship between the mind and the Measurement Problem.
 10:41: ... that the wavefunction collapse must be a continuous process between the measurement device and the conscious mind  and definitely not a sudden event caused ...
 12:09: ... not having settled the Measurement Problem  at least not with full consensus, modern quantum theory has ...


20200211: Are Axions Dark Matter?
 03:02: ... and negative charges  an electric dipole field. Our very sensitive measurements have found that no such field exists or if it is there then it’s a ...


20200106: How To Detect a Neutrino
 06:24: ♪ ♪ We can use our measurement to determine how much oscillation has occurred.


20191209: The Doomsday Argument
 14:06: ... slight positive or negative curvature just beyond the sensitivity of our measurement. ...


20191202: Is The Universe Finite?
 02:06: ... today  particularly the modern expansion rate determined from supernova measurements. ...
 04:46: ... always a degree of uncertainty due to the imperfect nature of any measurement. ...
 11:51: The tension between the Planck results and other cosmological measurements seems to be growing.
 12:30: ... them to construct equations of motion, laws of physics, and systems of measurement based on the algebra of quantum ...


20191015: Loop Quantum Gravity Explained
 03:54: Certain properties have an inbuilt uncertainty and only take concrete values after measurement.
 04:00: Absent measurement, they exist in a fuzzy space of possibilities called a wavefunction.


20190725: Deciphering The Vast Scale of the Universe
 04:36: ... Andromeda Nebula became the Andromeda galaxy and with more distance measurements it became clear that all spiral nebulae were island universes of their ...


20190715: The Quantum Internet
 06:23: To send that message, Bill performs a particular type of measurement on his qubits called a Bell measurement  not a 'Bill' measurement.
 06:32: ... this measurement simultaneously on A and C entangles these qubits but breaks the ...
 07:03: Now Bill takes photon A and entangles it with photon C using a Bell measurement so that now A and C have opposite polarization.
 07:44: This measurement outcome is encoded in two classical bits which Bill sends to Ted along the classical channel.
 07:50: ... the information in these two bits Ted can then calibrate a measurement of his own qubit B, after which that qubit will be in the state qubit C ...
 08:01: ... are only using photonic qubits then it's not so easy to perform a Bell measurement that will give all of the information we need for this final step, but ...
 08:54: It’s pretty much impossible to do all the transmissions, entanglements, and measurements in perfect synchrony.
 09:45: ... qubits, which they could use to communicate by exchanging classical Bell measurement ...


20190509: Why Quantum Computing Requires Quantum Cryptography
 08:51: If someone... not Eve ... Werner, intercepted these messages, which were after all sent on a public channel, and did his own measurements.
 09:37: Once they have done this test and verified that the information wasn’t intercepted, they discard the nonmatching measurements and keep the rest.
 11:18: Our choice of measurement direction will set the diection of those spin or polarizations axes.
 11:45: ... in a different basis to its entangled partner, the results of the measurements will be correlated in a way that depends on the choice of measurement ...
 12:23: Because they’re entangled, the outcome of Alberts and Niels measurements should be correlated in a very particular way defined by Bell’s theorem.
 12:40: But it was probably that Werner dude – he must have made some measurements and disentangled the particles en route.


20190424: No Dark Matter = Proof of Dark Matter?
 00:03: ... the orbits the Cosmic Microwave Background fluctuations also give us a measurement of the relative amount of dark matter in the early universe compared to ...


20190410: The Holographic Universe Explained
 17:02: Measurements of the geometry of the universe indicate flatness, but we may never know whether it's truly flat, or just flat as far as we can see.


20190328: Could the Universe End by Tearing Apart Every Atom?
 13:18: ... evidence that dark energy may be increasing in strength based on measurements of distant ...


20190320: Is Dark Energy Getting Stronger?
 05:21: It may be an issue with how we determine the starting conditions of the universe, or it may be our measurements of supernovae.
 05:38: But before we throw away the textbooks, perhaps we should think about where the measurements might have gone wrong.
 05:44: ... surprisingly, our measurement of the state of the early universe via the CMB may be more reliable than ...
 09:40: But if you make the measurement with enough quasars then this scatter can be averaged away.
 13:17: But the most likely explanation is still that concordance, LambdaCDM is right, and there’s an issue with the measurements or calculations.
 13:36: ... there are still relatively few very distant quasars with good Xray measurements, so maybe the random variations in the UVtoXray ratio by chance to ...


20190220: Secrets of the Cosmic Microwave Background
 11:14: ... the first peak to measure the baryon content of the Universe And those measurements tell use that that baryons constitute only about 5% of the total energy ...


20190207: Sound Waves from the Beginning of Time
 00:42: The impossibly vast distances made accurate measurements near impossible.
 01:15: Today, we'll talk about another measurement that may help resolve this crisis: The baryon acoustic oscillations.
 09:08: ... gives distance. And with careful measurements of galaxies' positions on the sky, a redshift survey can produce a ...
 10:47: ... then, the WiggleZ BAOs and 6dF surveys have improved the measurements/ Now, there was a powerful driving motivation to make this measurement ...
 11:00: Dark energy was first discovered by using distant supernovae as distance measurements to track the rate of expansion of the universe.


20190124: The Crisis in Cosmology
 00:13: ...have refined its measurement to unprecedented precision.
 00:49: Combined with the Doppler shift velocity measurements of Vesto Slipher,...
 02:51: Historically, measurement of the Hubble constant...
 04:15: ...and the precise measurement of the Hubble constant...
 05:18: ...to refine our measurement of H0 to ever greater precision.
 06:01: Well, in order to fully believe a measurement like this,...
 06:12: So it's a more or less direct measurement of the CURRENT expansion rate.
 06:37: ...or there is a big problem, with either our supernova measurements...
 10:57: ...in either the supernova or Planck measurements.
 12:26: The answer will depend on whether the more correct measurement of the Hubble constant...
 14:03: ...the gravitational lensing measurements of dark matter...


20181025: Will We Ever Find Alien Life?
 15:05: ... with scientific method using accepted protocols of observation, measurement, and evaluation of ...


20181018: What are the Strings in String Theory?
 00:59: We need to use physical measurement to fix 19 free parameters like the masses of particles.


20181003: How to Detect Extra Dimensions
 01:50: Among other things, this optical identification gave a completely independent measurement of the distance traveled by the gravitational waves.
 10:20: ... and the frequency of the wave combined with our independent distance measurement. ...
 14:10: This only works if the number of measurements you need to make is finite.
 14:14: For the simplest attempts at quantum gravity, you need infinite measurements.


20180920: Quantum Gravity and the Hardest Problem in Physics
 10:23: They can be brought back to reality by actual physical measurements of a few simple numbers in a process called renormalization.
 10:31: ... example, measurement of the mass and charge of an electron renormalizes quantum ...
 10:53: But unlike other quantum field theories, there are no simple measurements you can do to renormalize those corrections.
 11:00: In fact, you would need infinite measurements to do so.


20180815: Quantum Theory's Most Incredible Prediction
 05:58: So measurements say the G factor is around 2.
 11:38: This requires an independent experimental measurement.


20180801: How Close To The Sun Can Humanity Get?
 04:33: It'll make detailed measurements of their kinematic properties like velocity temperature and density.


20180725: Reversing Entropy with Maxwell's Demon
 07:08: Weirdly, it's not in the measurement of particle trajectories or the motion of the door.


20180711: Quantum Invariance & The Origin of The Standard Model
 02:49: The best we can do is make a measurement of physical observables, like position or momentum.
 02:54: The wave function can represent different observables and it determines the distribution of possible results of measurement of those observables.


20180704: Will A New Neutrino Change The Standard Model?
 09:35: This result is in conflict with some other measurements.


20180523: Why Quantum Information is Never Destroyed
 08:06: After all, doesn't the act of measurement pick a single value of some quantity from the range of possible values?
 08:35: And in principle, make enough measurements and you can extract all of the information from a wave function.
 08:50: ... to that interpretation, the active measurement actually alters the entire wave function causing it to shrink down to ...
 09:22: In the case of manyworlds, the entire wave function continues to exist even after measurement.
 09:27: That measurement itself is just a thing that happens in one part of the possibility space.


20180516: Noether's Theorem and The Symmetries of Reality
 10:39: But Gaia is really optimized for extreme astrometry phenomenally accurate position data that actually allows measurements of velocities.
 11:28: Simon Clarkston asks how Gaia can take such precise measurements.


20180509: How Gaia Changed Astronomy Forever
 02:07: Coupled with its incredible position measurements, this enables Gaia to measure distances to stars as far away as the galactic center.
 05:07: ... putting such complete velocity measurements together with our position data, it's now possible to model the dynamics ...
 06:27: ... by constraining the distances to stars, we can get better measurements on the sizes of those stars, and thus, also get better measures of the ...
 08:10: It does this by providing better distance measurements to those pulsars.


20180328: The AndromedaMilky Way Collision
 03:01: Hubble went on to combine distance measurements to many galaxies with measurements of their velocities to discover the expansion of the universe.
 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.
 10:25: ... one thing, there's the consistency of the dark matter mass measurements of galaxies and galaxy clusters from gravitational lensing versus ...


20171206: Understanding the Uncertainty Principle with Quantum Fourier Series
 01:59: And it's not just because our measurement of position requires us to interact with the particle, therefore changing its momentum, no.
 08:12: ... how likely we are to find the particle at any given point when we make a measurement. ...


20171129: Citizen Science + ZeroPoint Challenge Answer
 02:32: This international database houses over 20 million variable star brightness measurements dating back over 100 years.


20171122: Suicide Space Robots
 01:57: These measurements would have been impossible outside Venus' thick atmosphere.
 08:58: ... 1 still sends faint radio signals, bringing us our first and only direct measurements from beyond our home ...
 13:07: The paper claims the measurement of a real thrust.


20171108: ZeroPoint Energy Demystified
 01:26: This means we should take the idea of zeropoint energy seriously and are justifiably perplexed at the mismatch between theory and measurements.


20171019: The Nature of Nothing
 06:57: They live in the interval between measurements of real particles.
 09:51: Neither the Casimir effect nor the Lamb shift allow measurement of the absolute strength of vacuum energy.


20171011: Absolute Cold
 05:18: And this isn't about measurement.


20170928: Are the Fundamental Constants Changing?
 04:18: ... first measurement of this fundamental parameter was through its effect on the fine grain ...
 06:34: The key to this measurement is quasars.
 08:26: ... challenge here is that the measurement is really, really difficult. Photons from these extremely distant ...
 09:38: Well, any measurement of a change in Alpha may provide evidence to constrain the grand unified theories that predict such changes.


20170824: First Detection of Life
 00:12: To detect life on a planet based on measurements by a space probe.


20170802: Dark Flow
 05:02: A KSZ measurement from a single cluster isn't very useful.
 11:34: Upon measurement of the properties of the outgoing particles, weed entanglement correlations can still occur.
 11:41: ... the case of single entanglement, say, of two electrons, measurement of the properties of one of the electrons appears to influence the state ...
 11:57: ... if that measurement instead happens after the electron undergoes an interaction, represented ...


20170712: Solving the Impossible in Quantum Field Theory
 09:44: ... mass, and we know that because we've measured that mass, although any measurement we make actually includes some of this selfenergy, so our measurements ...
 10:05: ... you fold in a term for the selfenergy corrected mass based on your measurement. ...
 10:56: It can only make predictions of other properties relative to your lab measurements.


20170707: Feynman's Infinite Quantum Paths
 00:00: ... properties, paths, or events that could reasonably occur between measurements do ...


20170503: Are We Living in an Ancestor Simulation? ft. Neil deGrasse Tyson
 05:43: That's debatable, because the environment needs to be perfectly consistent with respect to all measurements made by all brains in that environment.


20170202: The Geometry of Causality
 07:59: ... itself comes directly from the Lorentz transformation, as the only measurement of spacetime separation that is unchanging or invariant under that ...


20170111: The EM Drive: Fact or Fantasy?
 01:23: ... Time Journal Club, we're jumping into Harold "Sonny" White, et al., 2016 "Measurement of Impulsive Thrust from a Closed RadioFrequency Cavity in Vacuum." ...
 03:24: The Eagle Works result is the latest in several attempts to reproduce Shawyer's measurements, none of which are close to being conclusive.
 04:10: Twisting of the wire gives an extremely precise measurement of any force.


20161130: Pilot Wave Theory and Quantum Realism
 02:36: ... and Heisenberg insisted that in the absence of measurement, the unobserved universe is only a suite of possibilities of the various ...
 05:01: Apparent randomness arises because we can't ever have a perfect measurement of initial position, velocity, or other properties.
 09:25: So a measurement at one point in the wave function will affect its shape elsewhere.


20161109: Did Dark Energy Just Disappear?
 07:28: Those blue ovals represent the ranges of combinations of matter and dark energy that are consistent with the new supernova measurements.
 10:20: The 1, 2, and 3sigma contours based on the CMB measurements.
 10:33: When you mathematically combine the certainty contours of two completely independent measurements they give you a much tighter range of possibilities.


20161026: The Many Worlds of the Quantum Multiverse
 01:45: And those many maybe histories somehow interact with each other to determine the most likely final destination when a measurement is made.
 02:04: ... the original Copenhagen interpretation of quantum mechanics, the act of measurement was thought to collapse possibility space into a single reality, at ...
 03:55: ... the doubleslit experiment and spookily correlated quantum entanglement measurements. ...


20160929: Life on Europa?
 09:45: ... you would get if you measured one particle with a verticallyaligned measurement device and a second particle with a horizontallyaligned ...
 09:57: ... mechanics is if you measure the spins of both particles with the same measurement ...
 10:17: ... spins in the same direction, depending on the relationship of the chosen measurement axis with the hidden spins of the ...
 10:42: That's because the measurement of its entangled twin forces its alignment to be 90 degrees to its own measurement axis.
 11:37: ... way of saying that is that this measurement interaction effectively entangles the measured particle and its partner ...
 12:47: ... no need for a fasterthanlight signal to tell particle a what measurement has been carried out on particle B because the universe, including ...


20160921: Quantum Entanglement and the Great BohrEinstein Debate
 01:48: ... the intervals between measurement, quantum systems truly exist as a fuzzy mixture of all possible ...
 02:08: And our experience of a welldefined material universe only has meaning at the moment of measurement.
 03:49: ... according to the Copenhagen interpretation, any measurement of one particle automatically collapses the entire entangled wave ...
 05:04: Measurement of the spin of one of these particles tells us the spin of the other, no matter how large the distance between them.
 05:10: But in quantum mechanics, measurement actually affects the thing you are measuring.
 05:15: In the case of quantum spin, that measurement effect is especially weird.
 05:31: We always find that the observed quantum spin aligns itself with our chosen measurement axis.
 05:48: Measurement forces the alignment of the measured particle.
 06:00: ... was right, imagine the response of each particle to all possible spin measurements is encoded in each particle at the moment of their creation as hidden ...
 06:28: But there'll be no correlation due to our choice of measurement axis.
 06:35: What if between creation and measurement, the electron and positron only exist as a wave function of all possible states.
 06:43: In that case, measurement of one particle spin should cause the entire wave function to collapse, to take on defined values.
 06:59: That should lead to a correlation between our choice of measurement axis for the first particle and the spin direction then measured for the second.
 08:11: ... found that there was a correlation between the choice of polarization measurement axis for one photon and the final polarization direction of its ...
 10:04: ... only possible to see the influence between the entangled partners after measurements have been made and those measurements are compared, just as we saw with ...


20160810: How the Quantum Eraser Rewrites the Past
 03:26: It's impossible to make these measurements without messing up the wave.


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


20160601: Is Quantum Tunneling Faster than Light?
 07:39: At that point, you can get an incredibly precise measurement of any differences in photon travel time.


20160518: Antigravity and the True Nature of Dark Energy
 00:56: Paradoxically, our measurements points a nearperfect flatness.


20160504: Will Starshot's Insterstellar Journey Succeed?
 11:49: There's a whole sequence of steps we use to calibrate astronomical distance measurements.


20160427: What Does Dark Energy Really Do?
 09:19: That's what we see in our white dwarf supernova measurements.


20160420: Why the Universe Needs Dark Energy
 01:41: There are two powerful and completely independent measurements that can test this prediction of the fate of the universe.
 01:48: Today, let's look at one of these measurements the geometry of the universe, which points to a discrepancy in the first Friedmann equation.
 06:21: So, did we miss up our measurements?


20160330: Pulsar Starquakes Make Fast Radio Bursts? + Challenge Winners!
 00:59: And that distance measurement allowed scientists to calculate the FRB power output as that of 500 million Suns.


20160323: How Cosmic Inflation Flattened the Universe
 02:57: Based on the precision of our measurements so far, we know that the curvature is within 0.4 of 1% of perfect flatness.


20160203: Will Mars or Venus Kill You First?
 09:28: The universe is 13.8 billion years old here, and that measurement of age is really just a measurement of how much change has happened in our frame.


20151216: The Higgs Mechanism Explained
 03:00: ... only way that we know that the tiny neutrino has mass, and it was the measurement of those neutrino oscillations the won the 2015 Nobel Prize in ...


20151022: Have Gravitational Waves Been Discovered?!?
 04:07: And so it's no wonder that gravitational waves remain the only major prediction of GR without a direct measurement.


20151015: 5 REAL Possibilities for Interstellar Travel
 12:04: ... you collapse the way function of one entangled particle, your choice of measurement affects the state of its entangled partner instantaneously, potentially ...


20151007: The Speed of Light is NOT About Light
 11:26: ... curvature is the maximum that it could be, given the current flatness measurements. ...


20150930: What Happens At The Edge Of The Universe?
 03:37: Given our best measurements of cosmological parameters, we think that the cosmic event horizon is around 16 billion light years away.
 05:18: Measurements of the distribution of galaxies and the CMB confirm this flatness with very high, but not infinite, precision.
 06:21: It's very possible that the universe has curvature just inside the uncertainty range of the best measurements to date.


20150422: Are Space and Time An Illusion?
 05:08: In contrast, our experiences and measurements of time and space don't correspond to anything, per se.


20150408: Could You Fart Your Way to the Moon?
 05:50: And if anyone is aware of documentable measurements of flatological exhaust speeds, include those too.


20150401: Is the Moon in Majora’s Mask a Black Hole?
 01:19: Both analyses are extremely well done, and I'm actually going to rely on MatPat's measurements in this episode.
 03:45: I've worked out the algebra using that MatPat's measurement of a mere 30ish meters for the radius of Termina's moon.


20150318: Can A Starfox Barrel Roll Work In Space?
 05:42: ... what a space meter is, which is apparently the official unit of measurement in the "Star Fox" ...


20150311: What Will Destroy Planet Earth?
 05:37: And those measurements, while not conclusive, do allow for a scenario that physicists call The Big Rip.


20150211: What Planet Is Super Mario World?
 02:55: ... turns out, other people have done more sophisticated versions of these measurements using Nintendo emulators, screen capture programs, and actual ...
 05:38: Remember, you could try this experiment yourself, even with rough measurements like mine.
 05:47: ... any actual planet, please let me know in the comments, along with your measurements. ...
