What is Relativity? | Sean Carroll on Einstein's View of Time and Space

#physics #theoryofrelativity #Einstein What is Relativity? | Sean Carroll on Einstein's View of Time and Space 302,009 viewsMar 8, 2021 Wondrium 428K subscribers According to Einstein's special theory of relativity, there is no such thing as a moment in time spread throughout the universe. Instead, time is one of four dimensions in spacetime. Learn how this "relative" view of time is usefully diagramed with light cones, representing the past and future. From the series: Mysteries of Modern Physics: Time https://www.wondrium.com/youtube/myst... 0:00 Understanding Cosmology, Gravity, and Relativity 1:00 Taking a Four-Dimensional Viewpoint of Relativity 2:15 Moving Into a Space-Time View of Reality 3:40 Differences Between a Newtonian and Einsteinian View of the Universe 4:45 The Notion of Simultaneity 5:55 Einstein’s Clocks, Poincaré’s Maps by Peter Galison 6:05 Recurrence Theorem 8:00 Einstein's Clock Patents 8:45 Constructing the Present Moment 10:40 Why Space-Time Is Relative 14:00 What is a Muon? 15:00 Carl Anderson Discovers Muons 15:50 Why Do the Muons Reach Us Before Decaying? 18:30 Einstein's Notion of Time as Personal 20:30 What Are Light Cones? 24:20 Time Dilation and Length Contraction 27:00 How Einstein Conceptualizes Space-Time 28:00 Newtonian Rule for Time Travel 28:45 Implications of Relativity ------------------------------------------- The Great Courses is the global leader in lifelong learning and our video-on-demand service The Great Courses Plus gives you unlimited, uninterrupted access to a world of learning anytime and anywhere you want it. 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Chukwu Igwe Chukwu Igwe 1 year ago I like how Sean Carroll explains these complex ideas in a way that is well within reach of the minds of non-physicists. Well done sir. 46 Ahmed Rafea Ahmed Rafea 9 months ago It is always a joy to watch and listen to professor Carroll. Complicated concepts are clearly explained and visualized. Thanks for this very informative lecture. 5 Nicholas Garcia Nicholas Garcia 9 months ago I always thought Sean Carroll was one of the best science communicators. Great to see him in his element like this 17 dennis galvin dennis galvin 1 month ago (edited) "There's no such thing as one moment spread through out the universe that everyone can agree on" [Sean Carrol] Interestingly the word moment despite being defined as "..a brief period of time" is in fact a brief period of an event because moment comes from momentum which is tantamount to events. Meaning that periods \ duration are of events not time. So events have duration that are measured by time as space has distance that's measured by the metric system or imperial units. What we perceive as the passing of time is just the passing of events. 3 J man J J man J 3 months ago Great job explaining complicated material! I find it interesting that our modern model of (space-) time, with its forward and backward looking light cones, looks so similar to one of our oldest timekeeping devices, an hourglass 1 Binu Varghese Binu Varghese 11 months ago Really very helpful to understand time... his explanation is very precise and even a layman can also understand the concept and importance of relativity and time 2 Sujit Kumar Dash Sujit Kumar Dash 1 year ago That was really a great lecture to watch. I got my own CONE out of intuition. LOL. Joke aside, To grasp such an idea of spacetime isn't easy as you might think ,but Mr. Carroll nailed it. Thank you sir. 3 Live īnfra Live īnfra 1 year ago (edited) Absolutely wonderful lecture , thankyou great courses plus for bringing these insightful sessions available to everyone 🙏 . 13 Wondrium gotatochigs314 gotatochigs314 1 year ago It's interesting to think from the muon's perspective, where the earth is moving towards it at close to the speed of light. The earth still reaches it before it decays though, since the earth experienced less than 2 microseconds of time along the way. 3 Dan Breeden Dan Breeden 1 year ago I'm very thankful for his teaching he presents his information very clearly 2 Wondrium Alexander Koryagin Alexander Koryagin 1 year ago Excellent lecture, thank you! 4 Wondrium Dmitry N Dmitry N 1 year ago Thanks for the great explanation! And for the undeniable proof that the past exists - the tie :) 5 Wondrium Eric Pham Eric Pham 1 year ago (edited) In multi body problems each axis has it's own time function depending on its acceleration therefore spacetime are bending and changing in multi body problem is mind boggling. Meaning our time is not known by another outside of our body and so are the other bodies. Just like the same harddrive memory could be used by many clients on same physical drive but the time of CPU and access time are different could get different data because of accessing method just like existence is different 2 Nah Bohdi Nah Bohdi 1 year ago He's one of the few people I disagree with in fundamental physics but still listen to for general discussion. 11 karlwashere123 karlwashere123 1 year ago Sean always crushes a good lecture 1 Shoaib Nature Shoaib Nature 1 year ago Thanks. I appreciate the time and effort to put all these information. 14 Wondrium Luca Luca 1 year ago prof. Carroll is phenomenal 3 Wondrium Roberto Escobar Roberto Escobar 3 months ago Simply wonderful. 2 Zack 120 Zack 120 1 year ago 12:37 - they came back with 'different reading' of time is because they were affected by different forces by each going through different path/speed/trajectory, while the TIME remains the same everywhere which is an abstract thing that nothing can change it, i.e. it is absolute. So the Newtonian theory seems to make sense. 1 harold floyd harold floyd 9 months ago (edited) Did Newton really have all that hair? I am skeptical. Love the “running back” analogy…the profound insight of relativity for me (that took me years to comprehend) is that C is the only constant, it’s space and time that are mutable, light speed never varies ever. 1 Randall Grubbs Randall Grubbs 4 days ago Time is: A measure of change in the entire existing universe, caused by the motion of matter/energy/fabric of space expansion in relation to itself. Because time is an emerging property of change/motion, time is relative to speed. If ALL change in the existing universe were to stop completely, there would be NO time. And in order to go back in time, you would have to REVERSE ALL CHANGE/MOTION in the existing universe to a previous position, which is impossible because it would require all (mass/energy in the existing universe) +1. Which, by definition, rules out traveling back in time. The Alpha Nigga The Alpha Nigga 6 months ago It must be nice being Einstein, he's given credit for things that he didn't come up with i.e Light cone idea, the spacetime-diagram as a whole, those are Minkowski's ideas. PoolBeast TV PoolBeast TV 1 year ago Amazing lecture This man has a wonderful voice 13 Wondrium Gotta Grab Gotta Grab 3 months ago I never knew there was a thing called "time".. so HUGE TY for telling me about it!! AL AL 1 year ago Maybe gravity exist only because we do. That'd make gravity very difficult to understand. The biggest problem with the theories about gravity is how far across space gravity, weak as it is, reaches out. It seems it's more likely that something, like warped spacetime, is what reaches out so far from objects, and when another object comes in contact with this their path is altered towards said object. WindUp Doll WindUp Doll 9 months ago "Like sands through the hour glass, so are the days of are lives" What are the chances that Newton and Einstein were both wrong? Its a simple probabilty equation with just a few theoretical factors. Bur the chances are as close to 100 percent as you can get. SunRoad SunRoad 11 months ago "Time taken in stocking energy to build an energy system, adding to it the time taken building the system will always be longer than the entire useful lifetime of the system." No system will ever outlast the Energy system that brought it to existence, regardless of its speed. Therefore, Time is universal. (A proposal, 2017). Marek Samsel Marek Samsel 5 months ago So many of these kind of. Vids yet this one, actually explains things in the most wonderful way, I'm impressed and grateful Colby Nye Colby Nye 1 year ago Fantastic lecture! 3 Wondrium NEW - KNOWLEDGE NEW - KNOWLEDGE 1 year ago How did he do it ? He looks so much younger. We, the people, believe he knows of, and has practised, time travel. Either that, or this one really old video. 24 yadan huub yadan huub 1 year ago (edited) I tried my best to compress the words and sentences ,and ignore things in between the thoughts and let the intelligence of the reader fill these gaps so we don't need to mention things twice. We need to distinguish between matter/energy level (where humans live ) and subatomic level where everything happening .The classic physics in matter/energy level cannot be applied on subatomic level, our observation is a reflection to what is happening on subatomic level including time ,for example, what we experience it as heat is actually atoms vibrating on subatomic level, and what we see it shinning is actually photons created and ejected from an object undergoing transformation on subatomic level. The whole universe works on subatomic level, The universe does not see sun ,earth , planets , trees and buildings. It sees concentration of particles that form these objects, and with particles it deals, any term in physics associated with matter/energy is meaningless or does not exist on quantum level including (mass,force,time,energy,...etc) so in this case any physical laws that include these terms does not apply on quantum level. We need to find the aspects that play role and the physical laws that govern them on inertia scale ,and they are thousands if not millions, the mathematical equations are few kilometers long,you call uber to correct something at the other side of it. We can understand quantum physic better if we use the term (behavior of particles of the universe) , there are nothing such as particles, there are only particles of the universe and the universe forces particles to behave on a certain way in certain conditions and one of these behaviors is gravity, gravity is behavior of particles, dark matter is behavior of particles , Why Oxygen is a gas and iron is solid metal is behavior of particles , Why photons penetrate glass and reflected on other media is behaviors of particles ,any chemical process or reaction is behavior of particles. Why some elements mix with each other and some not is behaviours of particles, Movement in space is behavior of particles, the electrical charge (- and +) are behavior of particles (so they are not properties of particles),double slit experiment is behavior of particles, the Gyroscope is behavior of particles, the speed of light is behavior of particles, and ALL fundamental forces humans know are actually behavior of particles ,particles change their behavior accordingly with the circumstances surrounding them The existence of black holes is still to be investigated ,but for the moment let's assume there is black hole in the center of each galaxy, the galactical behavior is totally different than the behavior of mass on smaller scale like planets orbiting stars and solar systems which controlled by what we know as gravity ,on galactical scale it is totally different (no matter if they are close or far from the center of the galaxy) , where the stars far from the center of the galaxy orbit faster than the stars close to the center of the galaxy ,The only explanation for this is that the behavior of particles is a function of distance (or space) let's take 2 magnets north and south and put them close to each other ,their particles will change behavior and pull each other and if we move them away from each other their particles behavior start to change, and the attraction force starts to weaken so space in fact change the behaviors of particles, the same applies for matter that circle the galaxy ,the space is much greater of matter in galaxies than space between the mass on solar systems ,that is why particles on galactical level behave differently. This was explained by scientists by the effect of dark matter So for all what mentioned above the origin of the universe was not the big bang but when particles started to get their properties and behaviors and atoms started to bond together and take shape to form matter and its companion energy ,the universe was different to what we see now ,The properties and behaviours of particle are ever changing ,and continue to do so for ever. Entropy is a good example for this. The issue with big bang theory is that it turned many aspects of the universe to constants, and we know very well that nothing in the universe is constant everything is changing all the time (including properties and behaviors of particles ) and everything is moving in space, and nothing is stand still. We have expansion of the universe and we have a big bang ,we just need to fill the gap between them and we have a theory of creation. The behaviors of particles in your body is reacting to ,the particles surrounding them ,the particles of the planet you are on, the particles of the solar system your planet in, the particles of galaxy your solar system part of, and particles of all galaxies in the universe, particles have multy behaviors at the same time. So if we remove all galaxies in the universe ,and only remain you and the most distance galaxy then the particles of your body will behave according with this galaxy. The change in properties and behaviors of particles over de course of time was not equal or at the same rate everywhere in the universe, some regions didn't develop matter yet or developed to different properties We can say that vacuum is existence, or part of existence ,and what applies on everything exists in the universe applies also on vacuum, but humans observe vacuum from their perspective in matter/energy level , if we want to know and identify vacuum from perspective of quantum level then it will be something totally different ,if we say vacuum is absence of particles (and I mean everything we call particle, even fundamental particles) then still vacuum is influenced by the same aspects of the universe that influent all particles and give particles their properties and behaviors, so vacuum in a way or another does carry the properties and behavior by the influence of the aspects of the universe and because vacuum fill the gap between particles (at least what we know till now) then vacuum play major role in "communication" between the aspects of the universe and particle. was the early universe only vacuum ,then particles started to emerge? Humans are limited to their senses and brain ability and accuracy of their equipment's so there are lot of aspects in the universe human cannot interact with for example multi dimensions so it will take some time to know what vacuum consist of and its behaviors and properties So any thing happening around us could be and must be explained on behavior of particles on subatomic level,the big masses matter on any size are eventually composite of particles..and the behaviour of their particles gives the big masses their behaviors and actions in space It is certain that all particles have no mass,mass only starts to build when atoms start to bond and make matter ,so anything more that 2 atoms have mass..mass is something associated with matter/energy level ,it is nonsens that some think that the mass of big bodies is the summation of the masses of its particles , Where are the boundaries?,when we are going to apply the quantum physics rules and when we are going to apply classical physics,explanning this is very long task ,but there is one principle here is that the formation of atoms from Hydrogen till atoms of heavy element all subject to quantum level and mainly ruled by behaviours of particles any thing comes after is subject for matter/energy level still we need to take into account that the bonds between atoms of the same elment,or the bonds between atoms of different elements are directly concidered as behaviours of particles,if we understand this it will lead us to know how all elements and anything matter or energy formed and have its own charastaristices and properties and their transformation froma stat to another and from sort element to another by fusion ,decay ,radiation or what ever process . Are life and biological realm a product or a consequence of behaviour of particles on subatomic level ,the answer is yes,The ingredients in humans body or any living body even small tiny single cell creatures are all made from the same elements that every thing in the universe is made off,the difference is that they have life,or what we call it life. So what kind and what percentage of each element available on a planet that have the right environment to support life would create what kind of biological world..? So it was not a spark. We see this very clear on differences between plants ,animals,humans and the biological world as a whole on each continent on earth it self,and it is an example how behaviours of particles follow a certain path when it goes higher in complexity level.So it was not spark. Venkat Babu Venkat Babu 1 year ago (edited) Relativity is the time differential of light to create mass. Everything moves at the speed of light except when slowed down. Karlos Jeffers Karlos Jeffers 1 year ago Can I go back in time and learn this fascinating science in school....when I should’ve been learning it? 9 Markus Pfeifer Markus Pfeifer 9 months ago Time is symmetric only insofar that the operator that has us move forward through time has an inverse operator that moved us backward through time. Yet, as soon as you bring moving objects into the picture, you can’t just rotate the time axis and expect to get the same picture. There’s actually a phase shift. One has to wait until the curvature of the object‘s time axis has inverted its direction on my space axes. Also, in the real world, the falling object would collide with something eventually and thus produce heat, i.e. entropy. Joseph Collins Joseph Collins 7 months ago I wish I had words to express how much I want to understand all of this. Why can't it be explained? You are the very best I have seen. I like the way you present (OMG, can I say that now?) and pace what you say. I am rather intelligent in everything else! WTF? Help!!! Kyles monster madness Kyles monster madness 3 months ago Man it’s amazing listening to you guys Wondrium Luke .Haidautu Luke .Haidautu 1 year ago (edited) I understand Sean's words, grammatically, but it's hard for me to understand the concepts that he's talking about. 4 Ryusei Iijima Ryusei Iijima 10 months ago this video or channel this is my first watch,this is a fantastic and brilliant video thankyou for great lecture sire Wondrium Neti - Neti ( नेति नेति ) Neti - Neti ( नेति नेति ) 8 months ago So, the speed of light measured by a person seating in front of a measuring machine that seats in Transilvania, Europe, Earth, that travels through a Galaxy in Universe that has its place in the infinite is not relative? Neil Libertine Neil Libertine 8 months ago Suppose a coach moving with relative speed to ground and there is lights at both ends. Time is synchronised for both observers in coach and at ground at the instance of light flashes from both ends of coach, also both observers are equidistant from both ends of coach at the instance of events. Now according to theory of relativity whose that version which is accepted by academician, observer in coach measures time taken by light on instance of flash from both ends is equal and there is no time difference for two events separated by distance, so events are simultaneous in coach. For observer on ground, according to above discussed theory speed of light is invariant to motion of coach and travels with same speed from both ends for instance of light flash at both ends of coach to observer on ground. Thus time taken by light from both ends is also equal for ground observer and both events are simultaneous. So two events are simultaneous as observed by two observers in relative motion according to theory of relativity as per accepted interpretation of theory. So in above mentioned example treated with special relativity, now discuss in terms of classical relativity. To those who didn't know about classical relativity, it was replaced by theory of relativity. Other than difference in scale conversion for relative measurement from theory of relativity, major difference is it had no special provison for speed of light as it possess no special quality for laws of mechanics when speaking about motion. For observer in coach sees time taken by light from both ends of coach is same because there is no relative speed for source and observer in coach. Therefore events are simultaneous for observer in coach. For observer on ground there is relative speed of source to observer, so speed of light must be relative. Suppose speed of light at rest is c and coach is moving with speed v to rest then from classical relativity, speed of light from moving source to rest is, c + v sin□, where □ is angle between perpendicular to motion of frame v and c, and angle measured positive if in direction of v otherwise negative. So speed of light from rear end is, c + v sin□, and speed of light from front end is, c - v sin□. As speed of light from rear end is more than speed of light in absolute frame, c, similarly speed of light from front end is less than c. Therefore time taken by light from rear end is less and hence event of light from rear end happened before from light flash at front end. So two events are not simultaneous for ground observer. Therefore two events simultaneous in inertial frame is non-simultaneous in relative motion according to classical relativity. Tony Hill Tony Hill 2 months ago You lost me at lightcones. But blew my mind with the muon thing. quannga99 quannga99 11 days ago (edited) Time as we think we know it is only a concept of the human mind. Time neither starts nor ends. Relativity effects of time appear only when we try to make measurements. Neil Libertine Neil Libertine 6 months ago Q. What is gravity. A. Gravity is phenomenon of objects falling down to ground with force and it seems that intensity of force or energy decreases with square of distance. This is observed on earth only that objects are pulled down but by inference we generalized it to whole planetary system and universe also. Q. What is cause or mechanism of gravity. A. Thermal energy emitted from sun generating pressure in space causing vacuum and thus creating thermal gradient for pressure wind. This pressure expand space by lowering matter concentration and further cause of motion of planets orbitting. Torsion by planetary motion concentrate matter to planets like cables. Yes this is possible explanation on basis of forces and matter in action. Gravity is equivalent to buyoant force in fluids. Q. What happen if star extinguishes or pressure cease. Does matter and large bodies lumps at centre and space is shrinked, like concept of black hole. A. Black hole is conceptual thing for purposed model to work. There is no observational evidence of any kind to prove its existence. No, large masses not fused at centre. First the vacuum created by pressure is filled with space matter that was removed and space becomes homogeneous of space matter. Speed of planets, which is same for given planetary system, continually slower down as resistance by matter increases. This arise two situation either radius of orbit shrink to keep speed intact and eventually planets merge at centre. This happens when star dies slowly, but if it dies abruptly which is more probable because power is constant, then angular speed of planets decreasing and finally planets comes to rest. Neil Libertine Neil Libertine 6 months ago What more observational anomaly than theory in relativistic gravitational theory is that inspite of big bang, orbits of planets are stable, atleast for many thousand years, also no detection of angular separation of stars. So meaning of stable orbits is that diagonal elements of mass-energy tensor are zero, because there is no expansion of orbits in radial direction. So i think there would no independent or orthogonal space-time coordinates, Theory could improve if they consider space and time coordinates differently. Time is part of space-time but not interfere length of coordinates of space. Thus space have 3 dimensions constituting volume and time is indicator of motion like orbit is clockwise or not and thus time in forward or backward direction. So space become a dimension and time another dimension of 2 dimensional space-time having volume. Other problem is that differential geometry or topology is construct based on idea or model which have flaws like length of curve is given in term of speed, so more curvature has less speed, but this is not as observed because distant orbits have same speed as nearer one, that is why different time period. It should be as, space is elongated and time is dilated so speed remain same, which is observable as distant orbits have bigger orbit and longer period. Relativistic gravitation was developed because in newtonian model not account for how everything starts from origin. It only account for stable orbit where orbital motion account for entropy or force in action. So what was before newtonian model could explain by relativistic gravity where diagonal energy have some value and cease at stability, it is transitory model. Mitch Raemsch Mitch Raemsch 3 months ago Move and it looks like other things do.. but Einstein left out it is always an opposite appearance. Begin to move and you see other thing appear to... but backwards. Look at the sky turning opposite the Earth. There is real motion that creates an opposite appearance. In history this was seen as retrograde motion. John Doe John Doe 9 months ago According to Gerald schroeder time started with the 1st matter the universe was 10.8 trillion times hotter than it is now. This means that time and space were also 10.8 trillion in times more compacted. Time 4 trillion times faster There's a curve from there to now the average of that curve is about one trillion but the universe is accelerating so you have to take off 10% which means the average time the early universe is point 9 trillion times faster So one day now would be 0.9 trillion days of the early universe 5.7 days now would be multiplied by 0.9 trillion divide 300 and 65 will give you about 13.8 billion years t 5.7 days now are about 13.8 billion years of the early universe another way to test this is for velocity if you were going 99..99999999999999999999999999999999 % the speed of light you would experience 6 days there above the universe and 14 be in years here Neil Libertine Neil Libertine 6 months ago So how would length of an object is measure. By placing it against standard scale, its one end is marked on scale then other end. The difference in value of two ends is length. One thing is assumed here that an object is at rest with scale which is also called as coordinate or frame. Now if an object have some speed against the scale or frame then does its length could be measured accurately. No, because it's not possible to mark both ends at same time and if object and scale have relative speed then one of end either contract or expand the measured length of object. This is relative measurement and when object is at rest with scale is proper or absolute measurement. Now relativists says that both measurement are correct and more than that if either object or scale is moving then relative measurement is giving actual description of object's physical quantity. So whether length contract or expand that relative measurement define physical state of object as by relativists. Further than that, in most conditions there is no frame moving with light speed and some events happening in it. Observation of planet is not relative because observer with scale like clock and angular scale is on earth. In case of far objects it's not possible to directly measure object so light is used. But relativists says that speed of light is constant whether source or observer have relative speed or not. First thing, general science laws doesnt allow it, second it require that light should have special quality which it has not so. In classical relativity that replaced by theory of relativity which we know now, has no problem with measurement of distant objects because its absolute and relative measurements are same so no problem. All problems start with insistence of relativists that speed of light is constant so they change fundamental quantities like length, time, mass. Suppose some children are playing in ground which is stationary. Now if an observer moving with quarter of light speed measure length of ground as per theory of relativity, found that length of ground is small as compared to what is told. Another observer with half light speed measure length of ground and found that length is contracted and also differ from first observer, then who is right, observer at rest with ground or moving observers. Does measurement of moving observers that differ from rest one, in any way affect or give actual representation, no. Same thing is with time, moving observers says children are slow. Does clock of moving observer change the movement of children on ground, no. Question is why they are doing so inspite of evidences against their theories. Reason is that constancy of speed of light is required for their model of universe, if that is changed then their model collapse. Aurélien Carnoy Aurélien Carnoy 1 year ago When a galaxy is moving away from us, thanks to gravity, falling in black hole, it is red shifted. When a galaxy is moving away from us, thanks the dark energy that causes expansion, that galaxy is red shifted. Could dark energy and gravity be the same force seen from different angle? 1 Matteo Ricchetti Matteo Ricchetti 2 weeks ago Inside an atomic clock an oscillator emits about 4GHz photon that reaches a Cesium atom, which absorbs and emits about 4G photon times per second. If I place a second atomic clock near a mass the Cesium atom emits 4G - a small value of photons per second. The mass influences what? The frequency of the photon of the oscillator? The oscillation frequency of Cesium? How ? By lengthening the space between the oscillator and the atom? albertods611 albertods611 11 months ago Terrific explanation Wondrium Walter Reese Walter Reese 3 weeks ago I wish you could ask questions. Mine would be "Why light cones instead of light spheres?" Neil Libertine Neil Libertine 6 months ago Is relativity against own foundation from its inception. Relativity is based on realistic view of Mach that there is no absolute motion, all motion are relative. They misinterpret it as inability to find absolute motion outside, thus relative measurement are real or actual measurement. While this is incorrect, because what Mach's principle means is, there is no need for looking absolute motion. Measurement in a frame is absolute and measurement of other frame is relative. So relative measurement is not actual or real even using Lorentz's transformation. We are not discussing here that how incorrect are Lorentz's transformation in relative measurement because they alter result of measurement of fundamental physical quantities. There is no agreement on these quantities if measured in one frame. Relativists are using self-defeating arguments. Suppose length of moving object is measured in inertial frame. An inertial frame is equivalent to rest frame if observing with in frame. Speed of ball measured in moving coach is same as on ground, one can play with ball in both frames without any difference. Relative measurement is observation of ball in coach by observer on ground or vice-versa. Question is, does observation from ground affect event in moving frame, no. Thus relative measurement is not actual if they differ from absolute measurement. Implication of this is that there is no time dilation or length contraction. Observation in an inertial frame is absolute. So there is no advantage of heliocentric model over geocentric, later is more practical. Also Lorentz transformation are useless because they have disagreement in absolute and relative measurement and thus producing difference of frame for observation, while they says that all inertial frames are equal, no preference. This shows that relativists preaching is different from practicing. Robert Ramirez Robert Ramirez 3 months ago If a photon were to wear a watch (silly but hear me out), that watch would never tick. Since the photo is massless and thus traveling at c, its movement in space-time is all in space and not at all in time. So in the photon’s context, time is still. And it’s not even traveling, because you can’t travel without time. The photon, to itself, is simply everywhere at once. Yet in our context, we see the photon move on the edge of the time cone. Therefor, I believe time itself is traveling at c. Light is riding the wave of time… How am I wrong? DM Returns DM Returns 1 year ago Why is it easier when Sean explains it? 1 paximaxi paximaxi 1 month ago It is unsettling how listening to a prof. Carroll’s lecture makes me feel a littler more educated and yet a complete troglodyte at the same time! Philip Nelson Philip Nelson 2 months ago How can you prove/ explain, verbally as oppose to mathematically, that nothing, as far as we know, can exceed the speed of light ? me you me you 1 year ago we should stop talking about "time" and talk about causality. Out of causality we get "time". Relative causality rate is influnced by velocity. packets of exitation (what we refer to as "particles") can only cause effects on each other (causality) at the speed of light, so the faster they travel the "harder" or "longer" it takes for that causality to happen, relative to same particles travelling slower (in respect to speed of light) 1 Eighth Gate Eighth Gate 1 year ago (edited) Light and the speed of it play the most important part of time! Dr.Jiradeach Kalayaruan Dr.Jiradeach Kalayaruan 12 days ago Thank you Teacher. moto theroad moto theroad 1 year ago When low entropy is created by new stars in our universe we would be going back in time if you believed in time. The universe doesn’t care about time. Sの Sの 8 months ago Thanks! I'm going to utilize this more. We would have time. ... Yeah, We are choosing the best choice for all of us. (Sorry for a unexpected message.) Edruezzi Edruezzi 4 months ago At less extreme conditions Newton's equations are derived from Einstein's. Miroslav Rusnák Miroslav Rusnák 1 year ago Imagine we stopped the whole universe. Now we can see that only space exists and there is only one present moment in the whole universe. 1 Nonconcensusical Nonconcensusical 1 year ago Time started when Dielectric energy decayed from the Inertial Plane/Counterspace. Inflation. Dielectric energy decays into Dielectric Voidance Field/Magnetism. The Grand Expand. Gravity is centripetal acceleration into the Inertial Plane. Gravity is Magnetism/Dielectric Voidance Field returning to Dielectric energy, then the Inertial Plane/Counterspace. Nelson Gonzalez Nelson Gonzalez 1 year ago I need to get back my time machine in order to travel through space and time. 1 Neil Libertine Neil Libertine 6 months ago What relativists thought of that by adding three variable of space and one variable of time, the space-time curvature equation became 4 dimensional tensor of rank 2, that is not case. To explain it, does surface of any shape for instance sphere is 3 dimensional or 2 dimensional in 3 variables. So metric tensor is 2d, 4 variable, rank of tensor represent dimension and root of elements of matrix is variables. They can think of that they have 4d equation so have volume and thus contain matter is incorrect. This is other thing that there is no physicallity of space-time unless they admit that space is not empty or vacuum, so again bring back aether in a sense. Also deformation is not possible in 2d surface. Also equation is written in reverse order, it is stress-energy tensor causing space-time curvature not otherwise. By measuring effect, one can measure cause, so by measuring curvature they can amount mass or energy but how space-time curvature could neasure is questionable. We are not discussing here how mass in space cause stress and how energy could be contained in no volume. This shows that big-bang model was prepared before because energy spread if it starts from point. Also we are not discussing that consequence of geometrical explanation doesnt meet observation, like time period of all planets should be equal, time is dilated in gravity but farther orbits are theoretically due to high speed and observed as time contracted in far orbits, opposite of time dilation. Yes, this model of gravity is not different from older model but attempt to give account for stable orbits. The multiplication of gravitational constant, G is for equating mass to force or weight. But instead of giving stable model of universe it leads to unstable model. STaSHZILLA STaSHZILLA 1 year ago (edited) Me: "Hey Sean, What time is it?" Sean: " Yes ." 28 Neil Libertine Neil Libertine 8 months ago If theory of relativity is true then there is no phenomena of interference or diffraction. And if we assume that speed of radio signal from 4g or microwave from 5g or oven is same and also equal to light ray, x-ray, gamma ray, then there is no efficient wireless communication possible which is now as that depends upon phenomena of diffraction. For non-sciencer diffraction means signal can reach at non-direct line or one hear sound from other side of high wall because sound is wave and wave exhibits phenomena of diffraction, compare it with non-wave like by hitting a ball to wall it not goes to other side without breaking wall. So only geometric optics is possible and source emits wave in form of energy having dimension of point in direction of relative motion, idea of light as stream of subtle particles. That is why they are in need of to explain wave phenomena by treating as particle, there is no coincidence that in opening of 20th century, suddenly rose in theories treating light as particle. So electromagnetic waves behave like gamma ray or even further and not like radio wave. No wavelength due to length contraction and frequency is so high it behave like no frequency at all. Sadly this is not observed so, either theory of relativity is wrong or their description of waves. جہيہفُہارا Guevara جہيہفُہارا Guevara 4 days ago Want to say that the industrial clock is more accurate than the movement of the planets? In any case Do you agree that there is no gravitational attraction for the Earth and for the rest of the planets? Baba Anyars Baba Anyars 1 year ago Space is moving/spinning and that motion is time. So we not moving in time but time is moving with us. David Wilkie David Wilkie 1 year ago (edited) Or, do Mathematicians who derived their formulae and practices from Navigational orientation techniques know that Singularity is "nothing but frozen phase-locked temporal substantion" ie a "Trig-point" @.dt, much like the 12 o'clock positioning indication in the picture of an analog Clock.., because it's how the abstract concept-in-isolation is applied to the Projection-drawing integration, of Metastable resonance integration in/of Polar-Cartesian Condensation innately self-defining coordination in/of QM-TIME Completeness, ..cause-effect that makes Zero-infinity the line-of-sight axis of e-Pi-i , the 1-0 probability dominance of "numberness", Origin. And if "you see what I mean" philosophically, Einsteinian Relativity reasoning demonstrates the impossibility of BBT.., because Everything is connected, by No-thing composed of E=mC² Black-body Singularity Conception Condensates, as suggested by Bose-Einstein. Or if you accept Newtonian Fluxions are self-defining Singularity-point positioning and shaping, in String Theoretical type Calculus. Or "Time is of the Essence", essentially hyper-hypo Superspin-spiral AM-FM, axial-tangential Renormalized orthogonality Math-Phys-Chem and Geometry in/of vertices in vortices manifestations, ..Atomic Spinfoam bubble-modes of Temporal Totality, ..and so on.. Neil Libertine Neil Libertine 6 months ago What people generally think of pressure as force per unit area, where area is 2 dimensional having no thickness. This is given by tyre pressure in unit of pounds per square inch, psi. The force exerted on inside surface of tyre by air contained in it. But this is half truth, in reality there can be no pressure on surface without having some thickness. What it means, that unit of pressure is given in 2d but it not applies on surface or area having no thickness. Imagine one having thin sheet of metal, now pressure is applied against thickness of sheet in form of hammering or weight. The metal sheet spreads out and become more thin. But if sheet have no thickness then no deformation. So how space-time given in 2d deformed by anything. It is other thing that mass is not equivalent to force unless it have some speed so having energy or under influence of some pull due to force or density. Similarly energy cant exert force unless it is contained in form of kinetic energy. If mass exert force then it is similar to Newton's law of gravitation, so what difference theory of relativity made. According to which black holes dont exists, they are against nature of force which is evident in big-bang model. Big-bang is expansion of matter and black hole is contraction of matter under same law. Differential geometry doesnt account for general model as they are for shapes and shapes are specific. Thus differential geometry of tensor not make equations independent of coordinates but opposite of it. It is also evident from model of universe as expansion. Universe expansion is transformation into planar space or euclidean space. While their model is flawed because expansion of a singularity is in first place having euclidean space. So their relation of mass-energy tensor to curvature of space-time is invalid because first tensor is operator and without specifying function it means nothing but numbers. Second thing mass and energy in itself no force so there could be no deformation. Third 2d surface cant have deformation whatever. Fourth there is assumption of surface prior to observation, it is assumed the shape of universe. This model of universe came is biblic in nature, everything comes from nothing. If one look at big-bang, it is culmination of their theory about universe, then how spreading of matter consitutes closed surface as spherical geometry required. Spherical geometry means closed body, having two opposite poles or sources, so no net source. This implies origin of universe from nothing. But two opposite source cancel each other to make region source free and if separated by distance cause directional movement result of gradient. Thus make work done possible. But their model ultimately ended in single point source of one kind when tracing backward in time. Mitch Raemsch Mitch Raemsch 3 months ago Time is a common instant for the age of the universe. Simon J Morley Simon J Morley 5 months ago Your real problem, Sean, is that you don't, even closely, seem to grasp the word Time. The ONLY empirical evidence of Time is change / change events (look around you - earth spinning, you breathing, quarks decaying - all change event series). Change can be quantum or compound, depending on your reference-frame. Change is hence reference frame (i.e. quantum) specific. ( also, spoiler, 'Arrow of change' [quantum], not 'Arrow of Time' [universal]). Time represents TWO distinct contexts of change: 1.The calibration of change (i.e. the dimension of change - hence 'rate' e.g. miles PER HOUR - the calibration of change of position aka motion) i.e. Time is to change what temperature is to heat, a dimension/calibration set. Temperature is abstract, heat is real, Time is abstract, change is real; and 2. Time is the collective 'flow' of change. Time is to change-events what 'River' is to water molecules - a collective term. But, fundamentally the word River is an abstract collective, water molecules are real. Time is a collective abstract, change-events are real - Time, the 'flow' of change. Time, one word, two distinct meanings, both reference change. AND THATS TIME EXPLAINED! All change is caused by energy differential (so, no, Time doesnt 'cause' anything). Time 1 measures Time 2. And Time 1 can be quantum specific (and hence reversible) and Time 2 might be universal. I do hope this helps... www.time-defined.com Neil Libertine Neil Libertine 6 months ago Serpents have fork shape tongue, metaphorically they are human who double talk. Similarly relativists, who profess theory of relativity, have logic of double talk. They says that time moves slower in presence of high gravity or force and speed is slow in high gravity due to curvature of space. At high speed which is far from gravity or force, time should moves fast as gravity is low. But their other part of theory says time goes slower due to high speed. But speed of body is due to curvature of spacetime and which is due to gravity or force. So what is movement of time farther from gravity, is it slow due to high speed or fast due to low gravity. Example is their explaination of time in satellites or they say that GPS and International Space Station. According to them time moves slower in them than earth because they are moving but at same time they are floating in less gravity than Earth so time should be fast. This is the condition of their theory and they keep bragging about it via various documentaries, channels, articles about their understanding and exploration of mysteries of universe. Tomas Eriksson Tomas Eriksson 4 months ago Always wanted to understand american football, thanks for the tutoring. dave z dave z 7 months ago In Galileo system, x=vt, if only if dx/dt is constant. Lorentz transformation goal is distances (x, x’) x=f(v,t)and x’=g(c, t’) are mathematically equal in both systems with symmetry. So c is not Galileo or classic velocity, and t’ is not classic time. In Galileo, v varies, t is uniform at any point in space; whilst in Lorentz, t’ varies, c is constant in space. c =eu , is really the property of the space, or medium, or Ether. It is not velocity in Galileo.( v, C),(t,t’), they are (Apple, Orange), (Peach,Grape) in two math systems. People are still thinking they are same things. That causes confusion. Saying 1) if an object moves at speed of light, time stops. Moving object slows clock, etc. That’s wrong. It should be said t’ in Lorentz stops, or equal to 0. In Galileo, t is uniform, it doesn’t stop or slow. 2). Speed of light C is constant from any observer at different speeds. That is wrong. c in Galileo changes from observers, C in Lorentz as the property of space is constant. Then there is no ambiguity, confusing, both accurate in their own system for/from measurements. Time dilution, space-time curvature, etc. are all bogus by mixing concepts in two systems. If you use Fourier series to express a signal S, it is not the signal in time domain, it’s amplitude A in frequency domain. Nobody treats A-S as “signal dancing”. But sigma of all these series by frequency goes back to the value of signal in time domain. They are just mathematically equivalent, not necessarily physically same. There are many ways to do it mathematically, too. Relativity is just another way of measuring of the nature using electric magnetic wave in Lorentz system. It has advantages over Galileo system in Astronomy, because Maxwells equations describe electromagnetic wave in vacuum with eu as constant, which is the space property and its value equals to speed of light in Galileo. In Algol events, it can prove that light speed varies with observer’s speed( visit Algol website) Dibald Gyfm Dibald Gyfm 4 months ago (edited) at 08:47 -- Suddenly I think that Simultaneity is impossible. Every lightray in the eye has wandered through space, and space is only possible because of individual time. ... or ... Cullen Cowap Cullen Cowap 1 year ago Sean was so tired of explaining relativity for the umpteenth time he forced Great Courses to release this talk. 7 Eric Pham Eric Pham 1 year ago The problem of synchronization was light and signal can not get straight line and gravity and even sound change light and signal plus other are localized Vikram Singh Vikram Singh 1 year ago saw this so long ago. big up Sean. Level of stripes! 2 Neil Libertine Neil Libertine 6 months ago There is no pyhtagorean for spherical or cylindrical coordinates. Then how should they use tensor as generalized coordinates, and how should minkowski space is correct. Differential geometry cant replace euclidean geometry which is generalized case and shapes are special. There is no great circle through points on constant latitude. So there is no geodesic for all points on sphere. a b a b 8 months ago How can we understand something our five senses can’t detect which basically are our tools to get knowledge. Corgicottage Corgicottage 3 months ago I guess if you know physics, this guy is clear. I dont know physics and to me he is confusing. First he says you have all the robots and synchronize their clocks. Ok, I get that. Then a few sentences later he talks about different people, not just you, sending robots up. That is confusing. I doubt I will ever understand spacetime because no one can easily explain it to me. Wardell Lindsay Wardell Lindsay 5 months ago The Universe is Space, time is fiction! You can create time as you want! Time = R/velocity = R/c, the fastest the velocity the shorter time! The Universe is a 4 Dimension SPACE, [SCALAR DIMENSION, VECTOR DIMENSIONS]. [SCALAR,] omni-direction [ , Vector] one direction. [Apples, Oranges] Einstein mixed Space and Time! wulphstein wulphstein 11 months ago Special relativity is the effect of units of wave functions expanding, like a water ripple, at the speed of light. 1 william gregory william gregory 1 year ago Thank you for a better nomenclature. Yash Gupta Yash Gupta 1 year ago Best courses Wondrium Amaziah Gamble Amaziah Gamble 3 weeks ago (edited) The infinite continuum of space time once believed, too, co-habit in a vast vacuum, where the solar system acted as an immense clock each orbiting In the story of origin woman was sculpted by a labor of love by God from the rib of Man in the garden. When I see the Life baring fruit of God's labor in love with Man. Then, I understand that God made woman for that reason, and purpose I fall in love with God in her temple at which point of designation in a different sphere of Time in space when observing the Step-Pyramid from a Birdseye view. For, instance the measure of a week on earth was one revolution from Ganymede around it's hostess planet,* where decades may be concluded in less completions around the sun. Days' were greater than years in Love on venus, and Seasons on earth can be determined by mercury in Months. 1 Eric Pham Eric Pham 1 year ago We can send the different kind of time function and not the counting time so it can change it's time by applied new formula of time function each time it receive and calibrate two system one mechanical time and one on atomic clock Paublus Americanus AMERICANUS Paublus Americanus AMERICANUS 1 year ago I don't know who Ponkray is but I have studied Poincare. An exceptional mind. 1 Mathew Anderson Mathew Anderson 1 year ago (edited) The 'clocks on spaceships' reference as a test idea, but then it was sad that relativity shows us that you can't measure time throughout the universe as one single moment that everyone agrees on. Key words here are "everyone agrees on" I feel. We should also hold to the importance of the idea that we can still identify a single 'moment in time', at least in principle. Say you freeze all of spacetime and look at it as a whole from a god's eye point of view. That's your single moment in time. Sure, the clocks of those spaceships and their viewpoints with each other will be different from their starting location, but that's just their rate of cause and effect (their time) changing. You can still justifiably state that picture as "a single moment in time", which if everyone could also look back and view, could all then agree upon that picture as well. Please correct me if I'm somehow wrong on this idea. 2 weegeepee weegeepee 8 months ago He explains very well, but I just don't understand. I am relatively dumb. :( Aurélien Carnoy Aurélien Carnoy 1 year ago 2:10 all points are identical. There surrounding is not. A point has zero dimension. I don't see how you can distinguish one point from an other exept using it's surrounding. By saying a point is in a 3d or 4d space is common but it is more useful to consider that in the point is the higher dimensions. Consider a point imploding. You still have your point and the dimensions within it. 🍻 cheers Elizabeth Parish Elizabeth Parish 10 months ago If an event is a moment in spacetime, does this have anything to do with a black hole's event horizon? Martin willemse Martin willemse 3 months ago A DOUBLE RED SHIFT A DOUBLE DISTANCE, THE CONSTANT OF HUBBLE? We take the light from a system with 10% redshift, that light enters the telescope here at the speed of light and has 90% of the 100% waves that were emitted per unit of time, if we let that partly continue to a galaxy that also has 10% redshift, then that light arrives at 19% redshift, if we shine light to that galaxy too, it arrives at 10% redshift, and since those galaxies are equally far away from us, there is no double redshift at double distance. To make that clear: if we receive that light with 10% redshift here at the speed of light, there are still 90 waves left of the 100 waves, if we let that continue to a system with also 10% redshift, there remain of those 90 waves there are still 81 left, if we also emit light to that galaxy with 10% redshift, 90 of the 100 waves will remain. Then those 81 waves will show as 19% redshift and the 90 waves will show as 10% redshift. Then there is no double redshift and double distance to be seen. Joshua Willis Joshua Willis 8 months ago (edited) I love Sean Carroll so much as a scientific communicator, but that muon explanation was terrible. The reason the muons are able to reach the surface of Earth is that they are moving incredibly quickly, and moving faster through spacetime makes elapsed time feel slower to the moving object but not the observer of that object moving at a slower velocity. 1 Musarit Rashid Musarit Rashid 6 months ago Time = change of matter and system. Truthsabre7 Truthsabre7 10 months ago Proof God created the universe. Can't have time space and matter unless it is all formed at the same time. neyney neyney 11 months ago Then there is 5 dimension. 3 space 2 time . Time localized is one dimension , the 2nd dimensional time , is the non local time . Can proved it .