I Never Understood Why Black Holes Slow Down Time… Until Now!

[@Mahesh_Shenoy]

To try everything Brilliant has to offer-free-for a full 30 days, visit brilliant.org/FloatHeadPhysics . You’ll also get 20% off an annual premium subscription.

[@shrivatsa8604]

Hello mahesh sir, nice explanation. Does time dilate more inside the earth compared to that on the surface?

[@sumansharma9794]

Can you please make a video on polarization of light.

[@Happybro91]

* Ek X Banda h voh earth se 9000 light years dur h ... * Uske waha gravity Kam h * Humaare yaha zaada * Humare yaha usko 9000 saal baad dekhenge toh woh ... * 6-7 hr jeeke ... * Par uski aging fast hogi .... * kya yeh theory sahi h ?

[@balabuyew]

@@Happybro91 Earth sucks space, like a vacuum cleaner sucks air. And since sucking is omni-directional, the space speed (relative to Earth surface) is greater near Earth than the speed at high attitude. As a result, a body near the Earth and another body at high attidue moves with different speed through the sucking space. So, according to special relativity, time ticks differently for them. If you'll take a flat infinite surface with uniform gravitational field, there will be no difference in grativy at different attitudes. So, there will be no difference in time flow. In other words, time flows differently at different attitudes because Earth is round.

[@michaelccopelandsr7120]

Thank you

[@SkotiM]

This is the second video I've watched on this channel. Both times I feel absolutely certain that I now understand this stuff, right up to the point that the video ends. As soon as the video ends I go straight back to not understanding it at all.

[@Ahoooooooo]

Thx . I'll stop the videos 2 minutes before the end 🫣

[@WistrelChianti]

I always find this stuff is like trying to insert a brick into one's brain, it's not a natural place for the brick to be, and as soon as you stop trying to force it in there, it just pops right out again. I've spoken to a friend who did Physical PhD about this he said this is normal and that conceptually it's just a hard thing to ram into our brains as it goes against so much that we think we know and take for granted in how we operate through life. The only way to do it is to keep coming back to it, keep thinking about it, keep watching videos etc. This is why there is the suggestion at the end of the video to try to explain it to someone else. That's a great way to check and re-enforce your understanding. It might end up messy where you make a fool of yourself because you didn't fully cement it into your head yet, but it's the only way to do it. At least for me anyhow and I'm still going with it.

[@camdoesitall]

You seem to be trying to grasp the idea the entire video than understanding it completely

[@wlockuz4467]

Fun fact: Watching this video on Miller's planet would cost you ~2.2 Earth years.

[@warhead213]

What?? 1 hour on Millers planet was 7 years… this video is 19:17 minutes long.

[@wlockuz4467]

@@warhead213 60 minutes = 3600 seconds = 7 years on Miller's planet 7 years = 220752000 seconds This video is 19 min 17 sec = 1157 seconds So we can do simple math; 1157 / 3600 * 220752000 = 70947240 70947240 seconds = 2.25 years

[@louied.quijano2254]

​@@wlockuz4467maybe you are Millerian. Your math is impeccable.

[@warhead213]

@@wlockuz4467 awhhhhh I see I see

[@JesusPlsSaveMe]

TO EVERYONE IN THIS CHAT: *THE JUDGEMENT OF GOD IS DRAWING NIGH.* REPENT TODAY AND GIVE YOUR LIFE TO JESUS TO ESCAPE ETERNAL DAMNATION!,..

[@devankurkashyap1031]

10:02 "That's what I am talking about!" I can't stop smiling. Your explanations are always to the point and easily understable, but these subtle comments, they are in the next level!!

[@JayMoreau]

6:32 in this example they are on the inside of the circle (orb), the outside would fling objects off. I’m honestly trying to understand

[@paulozavala3232]

Me to! I struggle with the same question! If you are standing on the globe from the outside (as we are) then the apple should just sky rocket itself out from earth or just spin around it as a moon!

[@sudhanshuaswal3113]

I am also confused here,

[@erikmin2625]

The point of the example is not to give an alternative explanation for earth's gravity, but to show that the effects of gravity and acceleration cannot be distinguished from each other. And therefore, the effect on other phenomena (such as the path of a light beam, or the passage of time) should be the same. In fact, an apple IS flung of the surface of the earth a bit by it's rotation - but the pull of gravity from the earth is much stronger. That is why gravity on the equator is a tiny bit less than on the poles - on the equator you have gravity minus a tiny bit of flinging off, on the poles just gravity.

[@UltimateTobi]

@@erikmin2625 But why bring this up if he doesn't proceed to explain how it works for Earth? As he said multiple times: there is no "gravity", gravity is merely the movement of objects towards each other. If you invert the images back and imagine them spinning, the apple would fly off into space if it maintains its respective velocity. So... it's a stretch to explain to the viewer something but then ask them to just "trust me" and not answer the question. He did mention another video where it's allegedly explained, but asks the viewer to stay and "not get distracted", but to be honest? He lost me there, because I need that question answered now, because he brought it up and it seems relevant to the rest of the video. If it isn't relevant, why bring this up at all?

[@CastAwayProduction]

@@UltimateTobi Has he explained in the video, the feel of gravity on earth is the fact that the ground is coming to you and pushing against you (the rotation of the earth has nothing to do with it). So it's kind of like if Earth was expanding at great speed, or like with his example, when you are in a car and you are pushed against the seat. But how can the ground expand without the earth getting bigger ? Well it's kind of an illusion, planet and stars warps space itself, like if space was elastic. So imagine you're standing on a carpet, and someone is pulling the carpet toward them. For you, you didn"t move, you are still on the exact same spot on this carpet so it's the other guy who is coming to you, even if he doesn't really move either. Replace the carpet with space itself and the other guy with Earth and voilà ! (Sorry for my english).

[@Pat_Fenis69]

This man had more conversations with Einstein than everyone that had conversations with Einstein put together squared.

[@WistrelChianti]

I really like his conversations with Einstein and the arguments he speaks. He's asking all the things anyone else would (and indeed probably already did - I'm sure Einstien had his work cut out even once he figured this stuff out. trying to explain it to anyone else.

[@Akagami2404]

Never stop making videos even if u get less views,some channels r really good and this is one of it

[@langleywallingford260]

Fewer views...

[@JesusPlsSaveMe]

TO EVERYONE IN THIS CHAT: *THE JUDGEMENT OF GOD IS DRAWING NIGH.* REPENT TODAY AND GIVE YOUR LIFE TO JESUS TO ESCAPE ETERNAL DAMNATION!,..

[@langleywallingford260]

@@JesusPlsSaveMe 😆

[@LostinMango]

​@@JesusPlsSaveMeWow I became christian after reading your comment

[@akashicrecords9]

Life's uncertainties 😂

[@YooooouKnowwwww]

if you're not a professor it would be a crime against humanity

[@BroadsideBob]

That may be how the math works, but one problem I have with interstellar is that Brand, Cooper, and crew needed a Saturn V rocket to leave the Earth at the start of their journey, but apparently a craft the size of a Winnebago was able to leave a more massive planet (with a deeper gravity well than Earth) and then escape Gargantua's even deeper gravity well later in the movie. I get that, "it's only a movie," but it seems inconsistent.

[@maxsamarin9002]

Maybe initially they needed the rocket to lift all the supplies for the journey?

[@DrRobot44]

Solid point… where was Kip Thorne on that one Nolan?

[@johndavidtackett]

Yeah def a movie with many issues, I appreciate how much they got right but def a lot of unknowns and some inconsistencies also which are to be expected since it’s a topic that we simply don’t know nearly enough about anyhow.

[@ulrichvonlichtenstein7880]

Strangely enough, it makes sense. The larger the object, the stronger its gravity is if you cross a certain point, i.e. the event horizon. The more massive an object, the less pull it has on objects in their orbit and escape velocity is actually way less than it would be if the object was smaller. Simply put, the smaller the black hole, the harder it is to escape it. If you want more on how this works, send a qustion to Neil Degrasse. He will do a better job of explaining

[@stephenperry9042]

​@@ulrichvonlichtenstein7880 Then why didn't the astronauts who landed on the moon need a bigger, more powerful rocket to escape from the moon since the moon is smaller than earth?

[@johnmacmillan627]

If you as a human have an ounce of curiosity then you absolutely must tune into this fellow’s videos. His wonderfully clear and enthusiastically presented videos are real gems not to missed. I marvel at his intelligence. I am almost 82 years old and am so thankful that I discovered his channel. Thank you, Mahesh, keep up the good work

[@IC0NICK]

I understand how centrifugal force works on a spacestation, because we are standing inside of the rotating object, and our feet are being pressed in the direction that is away from the center. But how does that translate to gravity on earth? On earth we’re not standing inside, we’re standing on the surface. So how does centrifugal force become gravity and not throw us into space? I’m genuinely interested. Forgive me for not understanding.

[@Wannakatana2112]

You're not The only one

[@minimumphase]

Now redo the explanation at starting at 4:41 with the part of ground inverted - the way it is on earth. With this explanation, the apple should move away from earth not towards it.

[@notafraidofchange]

6:34 … and less than two minutes later, Mahesh explains how the inverse is also true, how a rotating motion (not changing speed over time, like “straight motion” acceleration, but rather maintaining constant velocity and changing DISTANCE over time, which is also a form of acceleration), doesn’t necessarily make two objects fall away from each other and be flung outward into space (General Relativity and spacetime curvature expand upon how this is possible from a mathematical perspective).

[@UltimateTobi]

@@notafraidofchange He claims that, yes. But he starts to explain and demonstrate the first half, but then goes "trust me bro" on the second. It's unsatisfying.

[@BalthasarGelt-x2d]

The explanation is just an example of how you can accelerate without experiencing motion. Gravity on earth has nothing to do with its rotation, just its mass bending spacetime.

[@Hatemode_NJ]

This is the type of channel that should have 50 million subscribers. Don't stop what you're doing. You're one of the best at it. I've watched more videos on these subjects than I can count, but after watching only a few of yours, it all makes so much more sense. Not only that, I was able to easily connect other videos you made to related topics and they all come together in my mind seamlessly. It reminds me how my highschool chemistry teacher couldn't teach me something in a year that a college professor described in one sentence and I still remember it over twenty years later.

[@Hatemode_NJ]

I also want to add, the best part of your presentations is you ask out loud exactly what most of us are thinking in that moment and makes it seem as we are there with you.

[@flanker909]

The best way IMO to wrap your head around time dilation is to consider these facts: - Velocity: All celestial matter is travelling through spacetime (not floating) - all celestial matter do bend spacetime proportionally to their mass and density, the more massive and dense, the more bend their create - This bending combined with the velocity cause smaller/less dense bodies to orbit bigger/denser bodies - All is intertwined in this celestial trip (bodies ---> planets--->stars--->galaxies---->clusters--->super massive BHs---->....etc) - Speed of light is a constant (hard limit that applied to everything in this realm) So with the above intertwined parts, trapped in an endless race through universe, there must something that should be flexible enough to keep things moving in unison and that thing is TIME! Time can expand and dilate while speed of light can not! You can not touch or see time, its a variable that exists in the matrix source code that runs the cosmos. EDIT: I would also add that the way we have decided to measure time (days, hours, seconds..etc) and the way we got used to seeing time measured this way is the very thing that keeps us from understanding what time really is. I think that time does not exist, only spacetime (fabric of space) and the speed of light do. I would thereby join @liquidmagma and @mattgee4867 on this.

[@morgan5941]

Now tie your clock to a light year and it becomes a constant as well and not variable at all.

[@liquidmagma]

No. Time is essentially made up, or at the most a side effect of gravity and mass.

[@mattgee4867]

Time is not in the source code because it doesn't exist without an observer.

[@azilgaard]

Thanks. I guess your second point explains why the apple travels in a straight horizontal line while the ground travels in a circle...

[@austin3789]

The real answer is that the larger the amount of mass there is concentrated in a region the longer it takes the simulation to process and therefore time slows down.

[@vallabhdeshmukh79]

how do you know we are in a simulation😈

[@fridgeffs5662]

@austin3789 this is the best explanation that I have ever heard 😂😂

[@susanogranados5892]

Wow… you truly are one special kind of stpd!

[@DieBieneFranz]

😂

[@crooger3594]

Beautiful and complitely logical explenation, provided there are infinite nr. of sim. This argument is supported by math and history shows us that all natural phenomenas now seen as a facts, were initially theories supported by math.

[@Andrew-hp1yj]

I understood every word you used, I just didn't understand how you used them.

[@tschakatschada]

I feel that

[@sauravroy5737]

This is by far one of the best Physiscs explantion channel that I have ever seen...

[@JusticeLeGrand10101]

What? This video is horrible! You must be a fan. A fan of pseudoscience! Put down the pseudoscience and study astronomy. Read more nonfiction. Dictionary. Encyclopedia.

[@Verymusician193]

Science Clic English is really good too

[@overtoke]

being on earth makes you age "slower" too. no matter how 'slow' it gets you will always experience a normal flow of time from your perspective. like the water planet in the movie interstellar. they experienced a normal flow of time from their perspective.

[@Bellatticakes]

I am more confused than before watching this video

[@DhruvRed]

For the individual the perception of time will always the same but for the observer the time changes based on time dilation caused by moving at extreme speeds or extreme gravity

[@genghiskhan9200]

So the key To eternal life is moving fast 😄

[@philproffitt8363]

​@@genghiskhan9200Or maybe don't get a nosebleed...that's what finished Genghis apparently 😁

[@prahardarji6147]

​@@genghiskhan9200Nope for you time will always tick at the same rate, but u will be moving slower through the time "compared" to other's at rest. That's what relative means.

[@malvoliosf]

My question is, why would you think a planet so close to a black hole that time is slowed down 1000x might be inhabitable?

[@CheeseDanish85]

Because you want to spite the other scientist on your team who you think is being emotional.

[@Deezy_Ankh]

​@@CheeseDanish85that was for the other planet.

[@अपना_रोहित]

the gravity will crush you

[@malvoliosf]

@@अपना_रोहित “I WILL CRUSH YOU!”

[@ahmedyaseen5369]

But supposing that the gravity is tolerable, humans will live longer than on earth

[@erdrickk]

I'm trying to wrap my head around this, I understand being closer to a larger mass such as a blackhole, you physicaly slow down relative to others, being further out you're moving faster (assuming we are orbiting) what I don't understand is why there is a time difference and I realize its a real thing, proved with our GPS satelites and their clocks having to be very slightly offset. But from my perspective, if I'm seeing someone move faster, why are they physically aging ? I'm having an issue linking perspective of time and physically aging, are we saying the slower we move relative to others, the faster we move forward in time? I gotta eat some shrooms and rewatch this LOL

[@erdrickk]

Lets say Earth was 100x bigger and I was able to drill down near the core (super powers) and I setup a couch, my NES, Commodore 64 and Xbox 360 and gamed for 100 years living off of hot pockets and Redline, you're saying when I finally emerge, I will be younger than the people near the surface?

[@toxic7829]

@@erdrickk Yes. And also, you will have lived a good life.

[@toxic7829]

Yes. Think of it like this. There is maximum time OR maximum speed. So if you dead still, your time will go as fast as it possible can. And if you go at maximum speed (speed of light), the time will stand still. You cant have maximum speed and maximum time at the same time. It's one or the other. So lets change the speed with gravity and you get the same result. The higher the gravity, the less time moves. Higher gravity = faster acceleration. Now this isn't a scentific explaination, but it may help you wrap your head arround it.

[@rogacz962]

This video explains it poorly. For everyday experience we can separate space from time. We can do mental gymnastics of teleport an object from point a to point b without intervening space and in zero time. Or we can do the reverse, pretend something doesn't move in space, and only ages with time. Under special relativity, neither is possible. Space combines with time into one construct - spacetime. And everything moves through it constantly. There is no at rest. You're always moving. But there is a limit to that movement. 'C', speed of light. And from PRACTICAL experiments we know that that speed is constant, regardless of frame of reference. So as you accelerate towards speed of light, in order to keep your measurement of speed of light at c, something has to give. And it's your measurement of time. As you travel along light at speeds approaching 'c', light has less of a distance gain to you, but you still have to clock it at 'c', so the only way for that to happen is for your clock to slow down, meaning that for your measurement of speed of light there is 'more time', and light can travel 'larger' distance. Imagine there is someone walking 10 paces in 1 second. And that regardless of how fast you move, and which direction, you always have to determine that speed at 10 paces/sec. A stationary observer will see them move 10 paces in exactly 1 second. Now imagine there is a second person walking, one which the stationary observer sees at 5 paces/sec. But when that second person attempts to determine the speed of the first one something weird has to happen. They can see the relative distance travelled as 5 paces, but they have to clock the speed of the first person at 10 paces/second. And the only way for that to happen, is their measurement of time, ie how fast they move through time part of spacetime, slowed down, by half. You can think of this as that as you approach 'c' your movement through spacetime is getting more and more skewed towards space, and your time component is getting changed as well. And with the realization that spacetime is not homogenous, and is instead impacted by gravity (from either mass or energy), you can derive the exact same observations, except the dilatation will be caused by disagreement on distance travelled, not on time travelled. But it all comes back whether you can realign your expectation on reality to there being a constant speed, irrespective of frame of reference. It's a big mind hurdle, because it goes against everything your everyday experience has taught you.

[@cservonyec]

@@toxic7829 time is still an illusion. There would be no difference how fast time is between two individuals, one standing in the exact middle of the Earth on the centre spot, not moving in any direction, just spinning slowly with Earth's rotation and the other standing still in his bedroom. For both it takes Earth 24 hours to complete one circle, but for the one in the centre, it will be less perceptible then the one in his bedroom, where he can register the changes in daylight.

[@erdrickk]

referring up to the first 6:14 or so with your graphic of the two people in the ring, I don't quite understand, your graph is showing the people standing on the inside of the ring, so in this case your explanation makes sense but people don't stand on the inner crust of a planet, they are on the outside and when I imagine this same excercise, with the people on the outside, it doesn't make sense to me. Using your explanation of "no gravativy" they would be flung off.... Here's what I mean - Does anyone remember the Gravitron ride at country or state fairs? if you're inside the ride, as you should be, you're stuck to the wall - as described as per his graph - but we aren't on the inside, imagine riding Gravitron on the outside? obviously you would be tossed out lol, unless the atmosphere acts as a layer pressing us down? pressure? ok I'll watch the rest, I was just confused by this part and wanted to type some thoughts.

[@erdrickk]

ok, I shouldn't have watched this video high LOL but @FloatHeadPhysics explains it so well, I love it, now one of my fav channels and regarding my above comment, I am diving into space time curvature and sitting here starring into nothing just wrapping my head around this, makes sense and going back to about 10:30 he explains that so well, its common knowledge that GPS Sat clocks are offset due to the time difference but I loved his explanation. Anyway, high as fuck and loving this.

[@esotsm54]

Listen to me, you sir are the best KZbinr, period. Please never stop making videos

[@rihamission487]

How do you explain everything in one sitting? I haven't noticed any cuts, it's just you talking straight for 20 minutes without missing any points and with accurate emotions and energy. How is it even possible? You are a great teacher. Keep doing what you do. I cannot thank you enough. Your love for physics is unmatched. And ahhh I can finally watch Interstellar and actually understand a few things!

[@kcprdp1522]

Watch closely there are cuts and he is looking towards the side most probably at his notes, still it's good video

[@MrSean03839]

He has ads for brilliant, that's a break. Anytime there is an animation is a break.

[@Ravynheart]

there are cuts

[@carlossaraiva8213]

It's called learning.

[@troyfoster6004]

The way his hat sits on his head changes, telling me it was shot over two days. Very good video nonetheless.

[@DM-jo5ko]

Every. Single. Video. I am BLOWN AWAY

[@JusticeLeGrand10101]

Blown away by his imagination? Other than that, you need to read more nonfiction. Dictionary. Encyclopedia. Put down the pseudoscience and study astronomy. This guy is a clown!

[@DM-jo5ko]

@@JusticeLeGrand10101 there’s no way your aren’t trolling 😭

[@alexshatner3907]

I am really close to a brown hole within 3 feet and I am still getting older

[@shivamkumarshrivastava5182]

@@JusticeLeGrand10101 Aren't you the genius huh?

[@UltimateTobi]

Much better science channels out there. This is the second video I tried of him and he explains it poorly.

[@dr.syedinayatullah9125]

18:54 i think your observation is based on a hypothesis that either earth is pushing all objects around its surface with acceleration 9.8 or there is a centrifigal force from a center far away in the universe applying to all of us. Which one you are saying?

[@TomJones-op9nj]

Man !!! I look forward to going over your other videos your enthusiasm is absolutely contagious!!!

[@beepbop6697]

Love your vids that breakdown complicated topics into easily understandable chunks!

[@JusticeLeGrand10101]

That’s sad because if you understood this video, the only thing you understood was his imagination. Put down the pseudoscience and study astronomy for yourself. This guy is a clown! this KZbin video is promoting misinformation. read more nonfiction. Dictionary. Encyclopedia. put down the pseudoscience and study linguistics. silly Human!

[@Robinson8491]

Thank you Mahesh, for showing me the connection between the cycloid (a rolling, rotating circle) and gravity in General Relativity I was looking for for 4 years. And it turns out to come from the master himself, Einstein! I love it ❤

[@AtharvaBajpai-r5o]

he is a gem to the world we need to protect it!!!💖💖

[@bharathhm2215]

Hi Mahesh, Considering the image from the frame 10:15 of this video, We calculate Time = Distance/Speed. Having Speed as constant. We see the outer point can cover longer distance than the inner point as both points be on the same radius. So by doing maths we can see time with the inner point move slower than the time with the outer point. Which don’t accept Einstein’s theory?

[@satelliterain]

If all this is just perceptions of circular movement, then how does the movement of the Earth around the sun affect this model? Or the movement of the solar system around the galaxy? Or the movement of the galaxy around the universe? You seem to be only focusing upon the one spinning body model. It is so much more than that.

[@NewtonDKC]

What would happen if the people near the center of the rotating space station started recording 2 videos - one streaming live, the other a stand-alone space smartphone that begins recording everything live at the center of the ship and keeps recording continuously whilst traveling to the outer ring (and has storage and power that will not run out). The streaming signal is broadcast while the space smartphone is continuously recording live the entire trip (and is put in a little escape pod and ejected toward the outer edge or traveling inside the ship on a little delivery Robot if it’s all connected and can reach the outer edge people). When the outer edge people start receiving the streaming signal, what do they see? Are there gaps in the broadcast signal, or does it show the center ship people in fast forward gradually slowing down, or what exactly would it look like to the outer ring people seeing it? Now for the space smartphone: When they receive the space smartphone they stop the recording (which has been recording without stopping the entire trip from the center people to when it reaches the outer edge people). They now begin playing back the recorded trip…does the video, now playing in their reference frame but recorded from its point of view in its reference frame from the center to the edge, what would that video look like to them? Would it start out playing super fast and gradually slow down or just be a super long, super boring video of endless hallways and passing by in “normal speed”? And just to be extra complicated, what if there were 2 devices recording, one digital and one on an old analog film recorder with rotating gears and wheels and endless videotape - how would the digital video compare to the analog recorded video with both now playing in this outer ring reference frame but recording all the time between? Does digital recording have any difference to the analog recording that had gears/wheels while recording? From the recording device’s perspectives time has just always been the same, but when the people in the outer ring frame of reference watch the recorded videos,starting the playback of both devices at the same time and watch them side by side…do they see video and hear sound that runs at different speeds from the beginning to the end? Do the 2 devices vary compared to each other? Or is just a boring standard speed video on both devices? How does the recorded video compare to the streaming video (if it had been recorded by the outer ring people while streaming and now also played back starting at the same time as the devices that travelled from the center to the outer ring? Hopefully this is an interesting thought experiment and not so obvious that I dont later think “why did I even ask that?” :-) And thank you, love this sort of thing; thumbs up and Sub’d! :-)

[@Bleacher22]

For everyone local time is normal, universal limit of speed is speed of light it means for signals and travels.

[@actionpoker7C2H]

Loved using your relativity series to expand my knowledge and then finally intuitively demonstrate the concept of gravity being a fictional force to my friends. I made the flat spacetime graph, made the cone graph, and a figure to show Einstein's clock in like 15 minutes in a late night discord call. Started with Galileo's transformations on a train to introduce relative velocities, then used a thought experiment about what happens when Galileo lets go of the ball from the leaning tower of Pisa in terms of Newtons first and second laws of motion first from Newton's classical perspective where the ball begins to accelerate due to an applied force, and Einstein's where the ball remains at rest. Using your graphs, I showed how the equivalency principle shows us Einstein's alternative explaination for our observations. It was incredibly fun for everyone and I thank you for your efforts. For the sake of time (pun intended) and my own limited intuition I asked them to accept time dilation and that we observe it now in many ways but I suppose ill be threading in an imaginary space station next time. Its still hard for me to take a leap in this demonstration from objects accelerating toward eachother with zero relative motion to the idea they could accelerate away from eachother without relative motion. Luckily, I live in an area with gravity so I'm confident it happens 😂

[@JusticeLeGrand10101]

Your whole comment was based on imagination just like this video. Science rebukes imagination. Science is humans observing nature. Time, light and sound works simultaneously as nature. for example, we experience time through our star, the sun. we are our star. your imagination like this video is irrelevant. silly pseudoscientists! put down the pseudoscience and study astronomy. read more nonfiction. Dictionary. Encyclopedia. put down the pseudoscience and study linguistics.

[@steventreadway9966]

The concept of these physics are quite profound. Without time, motion becomes impossible. This also means that motion and speed are affected by gravity in crazy and unexpected ways. Simply being in strong gravitational field does indeed affect aging. So when we “measure” the age of our universe which is expanding, was a year really a year when the universe was more dense? It certainly seems that 1 year very soon after the Big Bang could have actually been thousands or even millions of years relative to a year that we perceive now due to the gravitational affect of so much matter being in a smaller volume of a more compact universe.

[@alexshatner3907]

I am really close to a brown hole within 3 feet and I am still getting older

[@MrMoose1347]

Without motion there is no time*

[@MrMoose1347]

Age dilation isn’t real only time dilation. Aka the clock count

[@alexshatner3907]

@@MrMoose1347 But without motion, why so much commotion? Conjunction, junction what's your function?

[@MrMoose1347]

@@alexshatner3907 and?

[@avendeep]

Concise and impactful I rarely comment online, but this video compelled me to. Had I seen such content a decade ago, my life might have taken a different course.

[@prakashs2351]

I have one doubt! Even though our time may look like slow but our biology cell will work every where same right. Why we are aging ?due to changes in energy production and our DNA is the factor for aging right?

[@maximivanov8467]

I've stumbled across one gap in the explanation that bugs me. In the spaceship, what really caused the time dilation isn't acceleration as such, it's speed. So to understand why gravity “causes” time dilation, we have to show that massive bodies somehow make everything nearby “move” faster. You've hinted at a solution out by showing that motion is a way to combine acceleration with constant distances, but it would be great if there were a way to demonstrate it more directly.

[@Mahesh_Shenoy]

"..isn't acceleration as such, it's speed". That's from the inertial perspective. From the perspective of the people inside the ship, they will attribute it to the centrifugal force.

[@shrivatsa8604]

You can imagin it like space itself is flowing inward towards the center, like water into a sink hole. When you are not resisting the flow you are under a free fall. And you are moving with your local spacetime but when you are on a surface standing, then you feel the force down at your feet , here you are resisting the flow of space hence you are moving through space , also the faster you move through your spacial dimension the slower you move through the time dimension.

[@akaHarvesteR]

Wow I came here to write _exactly this_. Wait, are you me?

[@youngguns2121]

​@@shrivatsa8604 this is a much more intuitive rationale than perpetuating the absurdity that all mass is under constant acceleration outward.

[@shrivatsa8604]

@@youngguns2121 👍🏻

[@PHIplaytesting]

These are the realizations that helped me understand relativistic gravity and time dilation: - The "speed of light" is not actually the speed of light but the speed of causality, or the rate at which things "change", which is what cannot be exceeded. - Energy is basically "change." - Matter (and therefore mass) is energy. The more mass, the more energy. - The time component of space-time is affected by the presence of energy, or "change," which creates 4-dimensional deformation and curvature in space-time. And finally, - Objects in motion (that aren't accelerating) move in straight lines, but _not_ in 3D space as we imagine. They move in straight lines in 4D space (which is space-time). When we project 4D space down to 3 dimensions, the way we perceive the universe, those straight lines appear curved. So basically, causality has a "budget" of how much "change" can occur over time. Change takes different forms, including velocity, mass, and other forms of energy. The more accumulation you have of any one of these things, the less you can have of the others (within the limits of causality). So we perceive an increase of mass or of velocity as a decrease in other changes which we perceive as a decrease in or slowing down of *time!* These changes in time cause space-time curvature which affects the paths objects travel, and that's how we get gravitational motion.

[@AnubisTheSonOfRa]

Half of your statements are kinda right and half of them are absurdly inaccurate and just not true.

[@PHIplaytesting]

@AnubisTheSonOfRa You didn't provide any corrections though, so relativistically they remain true from my reference frame. 😌

[@AnubisTheSonOfRa]

@@PHIplaytesting Did you just say “my truth-your truth” in other words? 😂

[@AnubisTheSonOfRa]

@@PHIplaytesting Just because you asked, I will correct one of your statements:- Speed of light IS in fact the speed of light! 🤯 Who would’ve known?!😬

[@pund]

@@AnubisTheSonOfRaNot him😂

[@Physicsislife07]

Sir I have an very complicated doubt in 16:22 mins that is Einstein tells that it is due to Gravity the time slows down but also saying it is nothing but an illusion so last time again can you tell what is Gravity and why it slows time and the g arrow why is downward not upward??? Please ❤❤

[@DrDeuteron]

g is down because if you drop something, it falls down.

[@varunvaswani4562]

If you may allow then I would like to give the possible explanation. At the heart of it, what we perceive to be gravity is the equivalent of experiencing an accelerated frame of reference. In any case, gravity is due to the acceleration of ground towards us, due to the curvature of spacetime. It slows down time because again, it's essentially an acceleration. As per the analogy described in the video, such an acceleration, due to time dilation and special relativity, slows down time. Lastly, the g arrow in the rotating spaceship must not be confused with it being a planet or black hole. It is the analogy used to show how greater acceleration induces greater time dilation. Since the outer parts have greater velocity, they have greater acceleration. Hope it helps;)

[@logicianbones]

Gravity is the ground pushing up on you more and more (ground is accelerating up -- ground is moving up and the rate at which it moves up is getting faster). Whether due to mass attraction causing more time (see his previous video that he linked) or due to a centrifuge.

[@jozincarnate]

So the arrows that follow Gravity, think of them as a accelerated velocity vector away from the center that linearly increases as the difference between it self and the constant velocity vector for the rest frame (I think I am near but something might have gone negative so can anyone help correct me?). But space is flowing to the center of mass as the earths expansion accelerates to meet it with a slight positive velocity? Pls help answer Adrito and correct any mistakes in any explanations!

[@kylelochlann5053]

@@varunvaswani4562 No, that's no right at all. Time dilation has nothing, per se, to do with acceleration.

[@iliyailiev962]

I got hundred percent better intuition of the whole time dilation. Crazy i aways knew the concept but never couldn't explain to someone as such that they can understand it. Crazy Videos man keep on going :)

[@dr.syedinayatullah9125]

14:50 seems like you are saying that gravity is only developed due to rotation not due to mass? According to this logic the earth will not have any gravity and no time dilation without rotation.

[@grobo503]

Rotation is just an analogy to the bending of spacetime around matter.

[@RicardoGarcia-sd1xb]

Amazing content as always!

[@Himanshu_Kumar_Sahni]

Einstein says that earth is accelerating upwards from every direction then suddenly put us inwards in a ring to explain that we are are accelerating towards centre, I mean dude seriously?

[@renedekker9806]

It is a comparison to make your understand that experiencing acceleration while not moving is possible. Gravity does the same, just in the other direction.

[@UltimateTobi]

@@renedekker9806 But why bring this up if he doesn't proceed to explain how it works for Earth? As he said multiple times: there is no "gravity", gravity is merely the movement of objects towards each other. If you invert the images back and imagine them spinning, the apple would fly off into space if it maintains its respective velocity. So... it's a stretch to explain to the viewer something but then ask them to just "trust me" and not answer the question. He did mention another video where it's allegedly explained, but asks the viewer to stay and "not get distracted", but to be honest? He lost me there, because I need that question answered now, because he brought it up and it seems relevant to the rest of the video. If it isn't relevant, why bring this up at all?

[@renedekker9806]

@@UltimateTobi _"So... it's a stretch to explain to the viewer something but then ask them to just "trust me" and not answer the question."_ - I cannot answer for Mahesh why he presented it this way, but I can answer why I would. It is very hard, almost impossible, to imagine the curvature of spacetime that General Relativity describes. We simply don't have the mental capacity for it. But we can draw analogies with other situations that we can imagine and that our intuition can understand. How things behave on a spinning disc, is one such analogy. Imagine a small room in the ring of a spinning space station, with its floor pointed towards the outside, and its roof towards the hub. What you would experience sitting in that room is very comparably to what you experience in the same room standing on the surface of Earth. When you let go of a ball, it will fall to the floor. You can feel the floor pressing against your feet when you stand up. The centrifugal (pseudo) force acts almost exactly the same as gravity does, only forcing you away from the centre of the disc, while gravity forces you towards the centre of a mass. But sitting in the room, and not knowing whether you are in a space station or on Earth, you will have a hard time finding the difference. The Equivalence Principle that General Relativity is based on, proposes that there IS no difference between them. That inevitably means that all effects that are observable in association with the centrifugal force must also be present in the presence of gravity. The time dilation that Mahesh talks about, is one such effect. _"I need that question answered now"_ - if you are seeking a deeper answer to the question why gravity works in the way it does, you are going to be disappointed. GR says that mass bends spacetime, and that this leads to effects such as time dilation. You can get a deeper understanding on what the all the effects are, and build up a better intuition about it. But the answer to the question WHY it works, is ultimately just: "because that it how it happens to be".

[@renedekker9806]

@@UltimateTobi _"So... it's a stretch to explain to the viewer something but then ask them to just "trust me" and not answer the question."_ - I cannot answer for Mahesh why he presented it this way, but I can answer why I would. It is very hard, almost impossible, to imagine the curvature of spacetime that General Relativity describes. We simply don't have the mental capacity for it. But we can draw analogies with other situations that we can imagine and that our intuition can understand. How things behave on a spinning disc, is one such analogy. Imagine a small room in the ring of a spinning space station, with its floor pointed towards the outside, and its roof towards the hub. What you would experience sitting in that room is very comparably to what you experience in the same room standing on the surface of Earth. When you let go of a ball, it will fall to the floor. You can feel the floor pressing against your feet when you stand up. The centrifugal (pseudo) force acts almost exactly the same as gravity does, only forcing you away from the centre of the disc, while gravity forces you towards the centre of a mass. The Equivalence Principle that General Relativity is based on, proposes that there IS no difference between them, and all effects that are observable in association with centrifugal force are also present in the presence of gravity. The time dilation that Mahesh talks about, is one such effect. _"I need that question answered now"_ - if you are seeking a deeper answer to the question why gravity works in the way it does, you are going to be disappointed. GR says that mass bends spacetime, and that this leads to effects such as time dilation. You can get a deeper understanding on HOW it works, and get a better intuition about it. But the answer to the question WHY it works, is ultimately just: "because that is how it happens to be"

[@XanBcoo]

​@@UltimateTobiI dunno dog, maybe go and watch the other video if you want to understand it?

[@DrDeuteron]

Another Banger, but I am concerned that you're perpetuating a grave misconception: that time dilation between two locations depends on the difference in their local gravity field strengths...which is a natural conclusion from the rotating wheel "model" (it's not a model: it is real gravity, but an analysis gets into Ehrenfest's Paradox, which is hole nother video). Bear with me: Where in Earth does time run slowest? Dead Sea?, Challenger Deep? The Kola Super-Deep bore hole? No: THE CENTER! (iirc, it has accumulated a 2.5 year lag since "The Beginning"). OK: what is the local gravity at the center of the earth: ZERO, ofc, by symmetry, shell th'm, etc etc. Time dilation between two points depends on the difference in the gravitational potential energy between the two points, and is not related to the local field strength, which leads to a fun fact: with Newton's kinetic energy KE = 1/2 m v^2 and Newton's potential energy PE = GM/r time dilation is: gamma = 1/sqrt(1 - 2E/c^2). with KE (PE) for relative motion (gravitational potential). with the formulae diverging at v=c and the Schwarzschild radius, respectively. Don't trust me bro, Trust Albert!

[@Mahesh_Shenoy]

Yes, you are right! I'll address this in the pinned comment.

[@theknown1741]

Time dilates slowly at the centre than on the surface? But how?

[@Happybro91]

​@@Mahesh_Shenoy* Ek X Banda h voh earth se 9000 light years dur h ... * Uske waha gravity Kam h * Humaare yaha zaada * Humare yaha usko 9000 saal baad dekhenge toh woh ... * 6-7 hr jeeke ... * Par uski aging fast hogi .... * kya yeh theory sahi h ?

[@DrDeuteron]

@@theknown1741 image the frequency of a photon (or a neutrino, if the shielding bothers you) as it leaves the center of the Earth. Is it fighting gravity and losing energy (frequency) the whole way up and off into space, or does it fall from the center up to the surface, and then start its energy-losing climb?

[@kylelochlann5053]

The gravity at the center is not zero. Recall that it takes 20 numbers to specify the gravity at a spacetime point. The Newtonian gravitational field strength is zero at the center.

[@PeterGoettle]

First of all your videos are great. They do a good job to help regular people gain intuition regarding these difficult-to-grasp concepts. I do have a question - at around 13:20 of your video, you mentioned that the person on the rim of the spaceship sees the clock of the person at the center of the spaceship tick very fast (i.e. the person at the center of the spaceship ages much more rapidly). but this seems to violate time dilation w.r.t. to the person on the rim of the space ship. or is there something about rotation that makes this (time speed-up) happen?

[@jusore]

If the flow of time depends on fluctuations in space-time, it would be interesting to think that the higher the density of space-time (center of mass), the more viscous space-time becomes and has a lower ratio of fluctuations, resulting in a slowed temporal flow in reference to others outside the reference frame.

[@guruyaya]

This is amazing intuition into a very hard problem. Great job

[@sdal4926]

I think Einstein would be proud of you.

[@dankuchar6821]

I'm sure he IS.

[@atheist8220]

He is not because he is dead. ​@@dankuchar6821

[@Bpg2001bpg]

Thank you. You are an amazing teacher.

[@Aeneas137]

instead of thinking of time dilation in terms of acceleration, I find it is helpful to visualize the space-time near a black hole is more dense causing everything to slow down. traveling further within the same distance.

[@MarkusBohunovsky]

Ok. Here's the problem though: How can black holes come into existence, given the time dilation around them? Let's first examine an object falling into the black hole. As the object gets closer, time slows down for it AS PERCEIVED FROM AN OUTSIDE OBSERVER. That means, for the observer, the object's fall towards the black hole gets slower and slower. From the perspective of someone inside the falling object, and looking back out, time in the rest of the universe speeds up more and more: So decades pass in mere minutes. Ok, now: As I understand it, by the time the object reaches the event horizon, its clock slows to zero (or the outside clocks speed up to infinity). What that must mean though for an outside observer is that the object comes to a virtual standstill before it can ever reach the event horizon. From the perspective of the object, on the other hand, they see the complete history of the universe pass on the outside (even if the universe was eternal) BEFORE they enter the event horizon. So: That means that for the outside observer (for example someone on earth) NOTHING can EVER fall into the black hole completely (during our lifetime, the lifetime of the earth, or even the lifetime of the universe). Instead, all objects approaching the black hole, appear frozen in time and space at some distance from the event horizon. --If this is not so, it would be great if someone could point out where my logic fails me here. Ok, now let's take this further and look at how the black hole comes into existence in the first place: A massive star is collapsing on itself and the matter at its center is getting more and more dense, as the gravity it “produces” gets stronger and stronger.
But that means that time at the center of the collapsing star starts to slow down more and more, which means that-again for the outside observer-this collapse itself should appear to happen more and more slowly. As the star gets closer and closer to becoming a black hole and forming an event horizon, this time dilation, again, should become so extreme that it slows time down to almost-and eventually exactly-zero, before that matter can ever become dense enough to form a black hole. Again, not from the perspective of the collapsing star itself, but from the perspective of the entire universe surrounding it. But that means, that it is not possible for a black hole to actually finish its process of formation during the lifetime of the Universe. I am not confused here: I know that from the perspective of the collapsing star there is no problem: It simply keeps collapsing, and may even do so faster and faster-but just like for the object falling into the black hole, from the perspective of the collapsing star, the time in universe around it goes faster and faster and the star would “see” the entire eternal history of the universe pass, by the time it becomes an actual black hole.
Again, from the outside perspective, the collapse of the star should slow down more and more, so much so, that it will appear frozen, before it ever becomes a black hole. So: how can black holes ever form within the lifetime of the universe? They could still exist, but they would have had to have been there from the very beginning. They could not have formed at any point thereafter.

where am I missing something?
 One point I am not 100% certain of is, if the event horizon actually represents the point where time slows to zero-since it is the point where light cannot escape, it seems to me that it is the point where time would also slow to zero, but even if it is not, there would still have to be such a point somewhere deep in the black hole, where the boundary of the singularity exists-so I am not convinced that this even makes a difference. I know, chances that you will actually read this comment are minuscule at this point, but a video on explaining why black holes can form in a region of space where clocks move at zero speed compared to the outside universe, would be really awesome!

 Cheers! Love your explanations!

[@socco90]

Nice read

[@qandak]

1:02 Apple is not an emmiter, it doesn't emmit any color. Instead, it absorbs all waves in visible spectrum except red, so you see reflected red color.

[@Ajunadeeps]

Oh 😳

[@ManishKumar-ui8pf]

Mind blowing animation sir

[@dsd2002]

if time dilation is because light photon moving larger distance at angles, then its just that photon clock is just measuring time wrong, but real time is not dilating, right? we are just measuring it wrong with photon distances at angles.

[@steventreadway9966]

@@dsd2002 something that is mind blowing is that every massive object in the universe is in different measurements of time due to both speed it is moving through the universe and through the gravitational field it happens to be in.

[@lj5190]

THIS. 100%. This is the exact thought I have whenever time dilation is discussed. Just because a clock is physically ticking slower doesn't mean time is passing more slowly. When the batteries in my kitchen clock start to die and the clock slows down, time isn't slowing down. A clock isn't time... it's just a tool for measuring it, and tools are affected by gravity. The same goes for aging. Time doesn't age us... multiple other factors do like nutrition, environment, stress, exercise, genetics, and yes, gravity. It's why some 60 year olds look 45, and some 45 year olds look 60. Time is a constant. It is only our perception of it that changes. A "slow" hour at work is the exact same length as a "fast" hour at play. Time itself is a dimension beyond gravity.

[@अपना_रोहित]

it is measured by decay... atomic clock...not by dial clocks

[@Bleacher22]

@@lj5190 Time itself doesn't exist, it's a derivative quality of a universe with its matter. Time is called a rate of changes, so if changes are slowing down it means time is slowing down. The speed of light is not just a limit of light, but of everything that exist including fundamental forces, so if those forces are slowing down in atoms then in chain reaction also in molecules and cells which controls aging processes, ultimately making us age slower.

[@lj5190]

@@Bleacher22 Time and rate of change are two different things.

[@salman127127]

I always wanted to ask this 2 question and you seems like can help me understand. 1) Why don't we use mechanical clock? which is working with same time interval without depending on reference frame. 2) What about our body clock how can it change? its biology and body is a separate system. I have lot of more doubts regarding the light and its speed I will ask after I get response to this questions first. Thank you.

[@goorlando1]

So good at explaining this. Really appreciate your drawings, put this in the classrooms. Love you

[@Jeremy-dy5zv]

My question is if the people in the ship had walkie-talkies would the person in the middle sound like a chipmunk with a high pitched voice because they are speed up?

[@Mr_Bones.]

No, the radio waves would also have to travel a further distance and thus come in at a slower rate

[@pleasejustlmb]

bro i looooooooooveeeeeeeeeeeee your videos. they are soo awesome and on top of that they teach me sooo much. i hope you heart my comment😁

[@michaelbuckers]

If you do the math on the Interstellar's black hole, it turns out to achieve this ratio of time dilation you need to be within 100 km of its event horizon, well within innermost stable orbit radius, so nothing except an accretion disk can even exist there, nevermind a planet.

[@jimsty7550]

Okay but the movies script was heavily critiqued by the world renowned theoretical physicist Kip Thorne. Nearly every part of it was heavily researched, critiqued and calculated by Kip Thorne. That said, I trust his opinion on Miller's planet being theoretically plausible more than your vague KZbin comment.

[@thehighway3695]

Wow bro you know a whole lot about something nobody's ever seen.

[@olisipocity]

@Mahesh, hi. I just happened to watch the video about gravity and the curvature of time first, and that video makes more sense and explains the gravitational effect better, so much so that it contradicts this one (in my opinion). Let's see. I can understand the concept of gravity being caused by centripetal force as demonstrated in this video, but this doesn't apply to our planet, because we don't walk surrounded by an external wall, on the other hand, this would mean that those living at the equator would feel the maximum attraction and those at the poles would feel its absence. Question 2: If gravity is a rotational consequence, what would happen to 2 objects with the same mass, but one rotating on its axis and the other stationary relative to its own axis? Would the gravitational force be different? In any case, the way in which the explanations are presented is really intuitive and explanatory, and makes us reason in a scientific way.

[@dennisk5818]

New subscriber, BTW. The title caught my attention, because this is one topic that I've really got to focus on. Your discussion seems great. But, having only a novice level of knowledge regarding Relativity, as an engineering/technical person, I'll have to repeat this a couple of times in order to draw my own metaphors and explanations.

[@chaos6876]

Why does mass cause spacetime to be curved?

[@mathura08]

Space curvature is just theory, it's just assumption We really don't know how gravity works practically

[@mathura08]

If time is really higher dimensional thing then I think we can't really explain how it works practically

[@jimsty7550]

It's because of the gravity produced by the massive object that curves the path of light. By curving that path for photons to travel, it slows down the photons, whereas on a flatter grid that is not being influenced by the gravity of a massive object but rather a smaller object of less mass, the photons move faster in that straighter line due to the weaker gravitational pull of the smaller mass.

[@jimsty7550]

@mathura08 say that to the people who have to account for the time dilation that occurs on our man made satellites in space. They move through space a little faster relative to anything here on Earth due to gravitational time dilation and scientists have to constantly account for the small time slippage in the satellites internal clocks because if they don't, things like the GPS's you and I constantly use would be completely out of whack. So no, it's "not just a theory"...

[@chaos6876]

Relativity doesn't answer my question because general relativity is just a mathematical model, derived to fit an observation(s). It can explain what is happening, but can't explain how it is happening. IMO, spacetime is the means by which everything is entangled at a quantum level. Here is another question: when a high energy photon decays into an electron and positron, what's happened to the original photon? Has it ceased to exist?

[@agg735]

I still didn't get it intuitively 😢

[@carlossaraiva8213]

The universe doesnt care if we get it or not.

[@Clarence_Oddbody]

Gravity doesn’t slow down or speed up time, because time only exists as a unit of measurement. What gravity affects is relative resistance. More gravity, more resistance, so our metabolic processes slow down as everything on a subatomic level is slowed by increasing gravity. In low/no gravity things move faster, so we age slightly faster as everything is moving faster with the reduced resistance.

[@Grysham]

Exactly, well put. Gravity and interestingly speed both map together to affect time (which is just the rate of change of mass within an spacial area). All that's really happening is the rate that mass changes on a subatomic level within the sphere of infuence is reduced by the resistance that high gravity or high speed pose. Considering that as you approach the speed of light, time for the object travelling close to the speed of light appears to slow, this suggests that it's to do with the resistance to changing energy states that's affected and that time (the rate of change) must be tied to energy in some way. The less resistance to the rate of change, the faster mass can go through it's subatomic changes.

[@Turbomantom2]

You're talking about gravitational stress, not "age"

[@havenp]

I absolutely LOVE the way you explore these concepts as a conversation with the physicists who elucidated them. I feel like this lays a foundation for true understanding of the processes rather than simply learning the principles and memorizing them. I’m about to complete a physics II course, likely the last of physics I’ll ever take because I’m studying biology, but I will continue to watch these videos because I think chasing a deeper understanding of our world as a whole is very valuable! Thank you!❤️

[@Eianex]

Okay the explanation is cristal clear and I love it. Question from previous video for the context to the current question. - But why time gets curved by mass in the first place? Why does Earth's mass equal more time at the ground? Edit 1: I've just watched this video and I will reformulate my question: Why do accelerated frames of reference (like the ones created by masses's accelerations towards each other) create time dilation in the first place? Edit 2: And why space also expands with mass?

[@mverus9460]

It’s because we move at light speed through space time. If we move faster through space there is less speed to go through time, and vice versa. Usually most of our speed is through time. But if you go very fast it reverses.

[@scorpionking8661]

I struggle with this theory. Time does not really exist… we as humans made it up and track it with clocks, watches, calendars, etc. you can’t slow down something that does not really exist. Our body clocks age at our own paces.

[@scorpionking8661]

Hoping someone can explain this to me.

[@Kishore_537]

I have the same question for a long time. We made the time to track some actions. But it is not constant for every planets. For example in earth 1 day = 24 hours. Which means 12 hours day and 12 hours night and it takes 365 days(1 year) to revolve around the sun. But for planet like jupiter 1 day is not 24 hours and 1 year is not 365 days. It will be more than the Earth. Because it is far away from the sun. So the 1 minute, 1 hour, 1 day, and 1 year are not Constant for all planets. Even though time concept is not constant. But 1 SECOND is CONSTANT in everywhere. And it can be slowed. So I don't understand what they mean by time will be slow? It will be different but not slow right? I'm not good in English. Hope you understand what I mean. Finally I found person with my same mindset in this topic. I need your reply soon😅😅

[@Grysham]

Totally understandable to struggle with this topic. Culturally, what we think of as time as a concept is very different to the reality of it. Time doesn't in and of itself exist, like you said. Instead time is a measurement of change. So why would that be different near a vlack hole? It makes a lot more sense if we think that when we age, when our body ages, what is happening on a minute level is the cells, molecules and atoms of our body are changing. Time is just a measurement of that change. So if something affects your bodys atoms in such a way as to slow down how fast they can undergo a state of change, that is what is "slowing down". Gravity affects space and time, when know this because when we use that model we can plug in predictions and calculations and they work, matching what we expect. Because of that we model gravity as bending space/time around it, like a ball sitting on a blanket bends the blanket around it. Gravity slows things on a subatomic level, so that a things mass (your body) undergoes change at a slower rate. Because everything is slowed, including your brain functions, it SEEMS like the rate of change for you is normal, but in reality it is just that the rate of change for your body and brain are slower than for an outside observer far away from the black hole. Time doesn't exist. All that's slowing down is how fast mass is changing states. Gravity affects that rate of change. Therefore, a black hole affects if even more because of how dense the gravity is around it. Let me know if that makes sense or if I can explain anything more clearly.

[@scorpionking8661]

@@Gryshamthank you!

[@Grysham]

@scorpionking8661 hey, glad that helped. You know whats rad? This whole thing of time dilation isn't limited to black holes. Those ones just have the most extreme (and coolest) situations. But here on earth we have to account for time dilation too. GPS satellites also experience time dilation, due to their distance away from the center of mass of the earth plus their relatively higher velocities orbiting the earth. This means we have to adjust our clocks to sync with GPS, otherwise you get innacurate results and the GPS doesn't work right. Same thing for space probes too. This is real science that we have to use here on earth.

[@hv9260]

So u r saying a tomato will perish quickly if its placed in merry go round instead if its placed away from it? When i as a child used merry go round in parks, i felt the world is fast forwarded but in reality its just visually moving faster. It didnt make the other kids in the park age more when i finished it. I still dont understand this time dilation concept.

[@WildAnimalsUncut3]

If his explanation is true, time dilation exists then it has to be demonstrated/experienced within this world itself. No changes is seen like in a merry go round, g-force testing sites etc....Nothing has been changed.

[@atheist8220]

Check time dilation formula. The velocity of object needs to be very high, at least a few thousand kilometres per second then one can see the relativistic changes

[@BriDog1474]

Having an instructor that truly want the pupil to understand the subject makes all the difference.

[@IainMacdonald-h4b]

Brilliant is exactly the right word to describe you. That explanation was so clear and to the point. Please keep making videos like these they are marvelous.

[@jerwaine624]

Great video sir! I have a question, if you have a fully charged battery in the higher gravitational field and I run wires to the lower gravitational field, will the battery last longer?

[@TazTalksYouListen]

I had to stop watching when you said 01:03 "apples emit red color" when they *_reflect_* red color.

[@atheist8220]

Bade hoshiyar ban rahe ho...?

[@ahmedyaseen5369]

But this explanation goes opposite to the fact that a guy in space would age slower than a guy on earth.

[@felixdempsey4919]

That's time dilation due to orbit speed, this is time dilation due to gravity

[@michaelsiggers1362]

​@felixdempsey4919 I'm with Ahmed. He 'said' the models were due to gravity and not speed, but I missed where it said why or how. All I heard was that time moves slower because we're rotating and we say it's gravity because it's simple, but its really just velocity. I know that's not right but this one was tough, unlike literally all of his other vids

[@NikkiTaLance]

@@michaelsiggers1362 Dilation due to gravity IS dilation due to velocity. Gravity is only a perception of what happens due to acceleration by those affected by it. The "gravity" itself doesn't actually exist except in our minds.

[@michaelsiggers1362]

@NikkiTaLance Hold on.... So we're only experiencing dilation and gravity because the Earth is spinning at the speed is spinning?? So if there were no rotation or movement there'd be no gravity??? This goes against everything I thought I knew about vectors and centrifugal force! By no means am I saying you're wrong, I'm just dreading having to go back to the drawing board😭😭😭

[@ahmedyaseen5369]

@@felixdempsey4919 both occure at the same time.. If an object is orbiting around a mass then it must be affected by its gravity, right?

[@JD-ow6sc]

Ok, none of this makes sense. Your example has the person closer to the middle of the object experience a faster clock and aging faster, while the person on the outside is traveling faster and experiencing MORE gravity but yet ages slower than the other person? Also the explanation of the earth pushing up instead of the apple falling down makes even less sense. In the example the apple continues to follow its trajectory until the earth rotates and stops it, giving the appearance of it falling, but if this were true then wouldn’t that mean if you were in the middle of the North Pole you would experience no gravity? Maybe I’m misunderstanding

[@Dirtynapkin]

1. Min 11:02 explains it, that the faster you move the longer light has to travel, because it's going a further distance. 2. That's because the earth is a sphere and not a disk. It's just perspective, you can't find the center on the outside of a sphere. I get it, it's confusing.😄

[@dallascowboy2221]

This playlist was way beyond excellent, thanks. I’ll have to watch it again so the concepts become easier, then I’ll explain it to others

[@skysheep747]

Hmm I still dont understanding why someone would age differently. If we are going off the theory of relativity and spacetime isnt it just our perception of time that is different? What if we used a different metric to measure time? Instead of using light (how long it takes light to travel from point a to point b) we measured using "biological time" such as half life or entropy?

[@lautben]

I love that you ask yourself the same "natural" questions i ask myself as the video progresses and you answer them one by one.

[@Tipounibouni]

Wouldn't it be simpler just to imagine that "spacetime" to be "absorbed" (as like sucked in) by gravity. I say this because when looking at your rotating turfs I was thinking why aren't we pushed upward by the centrifugal force? Regarding the time issue, my understanding is that each spacetime block has a fixed size. This means that when the space part is contracted the time part has to be dilated and vice versa. What do you think?

[@aronlisy6108]

Woow! This is an amazing video! TBH I was quite sceptical when I clicked on it, but it is so perfectly explained! Great job! I love it!

[@jnx2003]

This is the first video of yours that I have seen and it was very very good I will be watching more, thank you

[@JourdanRombough]

I enjoy your work and your enthusiastic teaching style - you have a bright future ahead of you, my friend... Thanks for the content!

[@DavidHockenberry-dn2gi]

Your explanation is the only way I’ve ever been able to understand this concept. Thank you so much

[@kalla103]

i love your teaching style and general vibe & i'll be binge watching all your videos probably

[@Superlativesweetie]

You lost me at 4:12. Why. is there an acceleration towards the centre? If they're attached to a ring, they're accelerating horizonatally along the fixed path. I thought that's how centrifugal force works. Objects are accelerating outwards but stopped by whatever is tethering them or blocking them.

[@narfwhals7843]

The acceleration inward is due to the centripetal force, not centrifugal. This is a real force. The centrifugal force appears because the reference frame that feels this acceleration has to "invent" a new force to balance the centripetal force since they don't see their own motion change. So to satisfy newton's laws, they need a "fictitious force". They ascribe various effects that only appear in their accelerated reference frame to this force. In an inertial reference frame, these effects just don't show up.

[@Superlativesweetie]

@@narfwhals7843 Ah, ok. Thank you! I didn't know that word. I read the wikipedia page about centripetal force, and it describes the force coming a source, like a tether or a barrier. That part makes sense to me. In this video, he's saying they experience centripetal force, which I guess comes from the pressure of pushing against the platform as you move horizontally forward and the platform follows the circular path that cuts you off. I'm still having a hard time reconciling that feeling of there being a force keeping you from spinning out with the idea that you're actually accelerating towards the centre. And then I get completely lost again when you invert the chunks of land and the girl doesn't fly off of them as it continues to spin. The curvature of spacetime, what?

[@John-jd7mm]

@Superlativesweetie "Centrifugal" force is a 'phantom.' It appears to be there, but is not. It is the apparent result of the addition of two directional acceleration vectors: (1) tangential (in a straight line, constantly changing along the arc of a circle.) And (2) centripetal (it is the force pulling toward the center) What is centripetal? For example, spinning a rock attached to a string, you are always pulling it toward your center of rotation (your hand). If the string breaks, the rock keeps flying in a straight line. But since it doesn't break, you are constantly pulling it into the center. And since this is a force you apply, and the rock has mass, there is a "center-seeking" (centripetal) acceleration due to Newton's 2nd law of motion. Fc= mAc. (better, Fc/m = Ac) where F is force, m is mass, Ac is centripetal acceleration Thus it appears there is an *"outward"* force, where there is none. Only an inner-direction force. It does seem counter-intuitive, I know. I hope this brief explanation helps.

[@Superlativesweetie]

I found this video really helpful: kzbin.info/www/bejne/joPVYp6XjbB1qbc&ab_channel=Veritasium

[@orrlevinger]

Never seen such an intuitive video! And with so much passion! Please never stop!!

[@jaredrivera2619]

Brian cox does a great practical explanation of this. Its not really gravity that dilates time it's movement through space time and lights constant speed regardless of reference frame. In interstellar the exoplanet is moving at high velocity because of its proximity to the black hold is that velocity not the gravity itself that creates the time dilation.

[@pks2552]

The qualiry of your contect is way abouve channels even like vertasium. Thats what I feel. I had cofnisons on relativity for many years. Thanks to you that things are getting clear

[@shankar7435]

By far the best explanation for the time dealation till date I found. Thanks.

[@Ozzah]

I like that you essentially derived the underlying mechanism for WHY time ticks at different rates, essentially using photon clocks. However, I find the model much easier to understand where we are always moving through spacetime at the speed of light, so moving faster through space causes us to move slower through time, and vice-versa. Add to the curvature of space under gravity and objects not under acceleration always moving in straight lines through curved spacetime.

[@20.keshavmore86]

I discovered this channel and oh my i am just binge watching every video. Your explanation are brilliant. Better then veritasiums explanation. Keep going 🏆

[@kenk5269]

surprised with the very clear explaination. its so digestable and easy to understand.

[@aristideau5072]

Soooo, by your rotating spaceship example, time dilation can be manifested via the pull experienced by centrifugal force and the same time dilation can be also manifested via the pull experienced from being in the vicinity of a large mass?. Is so, then this kicks the "how time dilation occurs" down the road with the question now being "how are the "gravitational" like effects from centrifugal and mass equated"?.

[@bestallrounder244]

WRT the person at the center of the spaceship, the person at the far end isn't moving and remains at rest (assuming both are standing). If their relative velocity is the same but their time flows differently due to varying acceleration and increased gravity, it would be strange. The person at the center would see the one at the far end waving their hand in slow motion... your explanation just made another of reason of time dilation more clear to me!

[@Avasarala12]

Hi Mahesh, really appreaciate these videos. Thank you so much for these! I have a couple of queries about the escape velocity bit. May be someone from the chat can clarify these to me : 1. Why does the escape velocity change at a given radius from a collapsing star at all, when the star does collapse. 2. If the Newtonian gravity has a concept of Event Horizon, it'd be the spherical surface where Vesc = c right? doesnt that mean the thrust force a rocket would need to be greater than a gracity that demands c to escape and from relativity/your previous videos, it'd take infinite amount of energy to accelerate to c ?

[@אלעדקדוש-נ8ש]

you are the best teacher by far ! I love your videos ! I have another way to explain this but I am not sure if its correct or not. the big mass of the star (or blackhole) creates curvature in space time, which make the space around it more dense. for example 100 meters in empty space will dense into 20 meters around the star. so when I travel 20 meter near the star I actually traveled 100 meter at the same time. which means I moved faster by a factor of 5. thus creates the time dilatation due to faster speed.

[@AbhishekVerma13]

@maheshShenoy I still dont understand your exlaination. When someone travelling planet near blackhole, I assume that blackhole is a heavier body and all planet or spaceship must be rotating around blackhole. From this thought spaceship in intersteller was far from blackhole, so its time must be slow , or do we have to see what blackhole is rotating around (even if its roatating around any other body or not). I think we have to see in this frame of reference .. and I think it should be other way around,far from blackhole must be slower. Also 23 years of time difference should mean that distance between both clock should. bereally long. how long? is there any way to calculate this? and how much time do a spaceship need to travel this distance? i think it has to be really long time, unless they are travelling close to speed of light

[@llamaseca]

Recently discovered your channel and love it! In relativity, I always find it hard to distinguish cause and effect. Even when relationships are perfectly described, thinking it through often seems to end in circular argumentations. In a previous video, you show with simple elegance how time dilation causes the illusion of gravity by making the ground accelerate, did I get that right? Now you show how the ground's accelaration causes time dilation. What am I missing?

[@UToobist]

Well done! I now have a good intuitive feel for time dilation with relativity. Tell Einstein thanks from me next time you talk with him! I also want to share my way of thinking about bodies moving in space time and the link to quantum mechanics. A particle, and the body comprised of a big set of particles, travels through space time by slipping from one point in space time to the next. This is done at a rate that is somehow related to the wave vibrations at the most basic level. I think of it as blinking. If the particles and the body they comprise move faster through space, then a larger component of the blinking (which the particle does as part of the essence of its existence) is used getting from one point in space to the next and less is available for getting from one point in time to the next. It helps some to think in terms one dimension of space, the one the body of particles is moving in. The trade off between moving in space and moving in time seems more symmetric. The fastest the particles can go in space is limited by the blinking rate, which is what gives rise to the speed of light limit. At that speed the particles do not experience time passing. As the speed slows, there is more blinking available for time to pass. The effect of mass is to compress things for the blinking of the particle, which bends the particle towards the mass. The compression makes the blinking occur over shorter distances and times, which pulls the particles inwards towards the mass. As far as I can tell, none of this contradicts relativity or quantum mechanics. Now, one implication of my intuitive model is that if a particle slows enough that it reaches the fastest it can go through time - that would be when the particle is effectively at rest because none of the blinking is left for going from point to point through space. It is the analog to the speed of light, what I think of as the maximum rate of time, or the resting blinking rate. Does that perhaps provide an approach to some mathematical treatment of my intuitive model and perhaps even a way to develop some sort of empirical testing?

[@pauldacus4590]

I think it should be pointed out that it is not the "feeling" of gravity on the outer ring of the spaceship that is slowing the clock. When you fall into a black hole, you don't feel gravity, but your clock is slowing. If you dropped out of a hatch in the outer ring of the spaceship and were flung into space, your clock would also be slow in comparison to the person in the center even though you wouldn't feel "gravity" anymore.

[@AdityaRaj-hn5bm]

10:40 - If a quartz clock was used instead of a photon clock, how can we explain the dilation in time?

[@c.jishnu378]

It's not about clocks, it is about that if a clock could be there, then if it behaves that way then it would behave that way without the clock.