Why does time slow down near a black hole? (But, you don’t age slower) 

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

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!!

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

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.

Every. Single. Video. I am BLOWN AWAY

5:35 my brother, I love watching these type of videos, although I may not understand 90% of it. Let me just say it 5:30 mark, the way you broke down the apple falling towards the ground versus the ground, moving in the path of where the Apple was going just blew my mind. I never make comments on pages, but I’m taking time to tell you, bravo. I’ll be following your page for a long time!

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.

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

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

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

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!

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.

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 😂

I think Einstein would be proud of you.

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

Amazing content as always!

Thank you. You are an amazing teacher.

I thought I understood "why the clocks tick slower", but after this video, I realise I only "knew that clocks tick slower" without fully understanding why. This explanation helps me see why...

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

Bruh... That ad transition was straight up devious... Bravo... Bravo

Mind blowing animation sir

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.

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.

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

I think comparing gravity (which is not a force) with a centripetal force (which is a force; the electromagnetic force to be exact) will only help as an intuition for what is actually happening and only muddles the water from there on out. The difference is that the centripetal force is actually accelerating the observers where as it's the space-time curvature itself that is responsible, which is definitely not an acceleration. Problem now is that we are back at the question from the beginning of this video. You should have sticked with your older explanation, which I'm glad you mentioned so that other people can learn it the proper way. 2 objects falling onto earth at different altitudes with the same initial speed will have different moving clocks although they don't accelerate; they are just moving in a straight line trough curved spacetime, meaning no acceleration and no change in their speed; and yet time dilation still happens.

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! :-)

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!

I've still never fully got it. I understand that it slows time down, dang near to stopping it in a black hole, but I always can't help but think from an outside perspective. If I am watching a person near a black hole, and one way out in space, they should both age 24 hours on my clock if I watch them for 24 hours right? Just never understood how one covering more distance affected time. Time is only particles moving position, even objects setting dead still have subatomic and atomic particles, cells, etc. moving all over. So does heavy gravity just slow ALL particle movements?

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 ❤❤

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

Your visual representation is wrong. The two land surface should be outward and the force that pull in is centripetal

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!

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😁

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?

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

Congratulations, you have just convinced people that the rotation of the Earth causes gravity.

I can't get enough of the intuitive explanations. The model is inverted in respect to the observer to simulate gravity so the direction of the simulated gravity is also inverted in respect to the observer. I almost got hung up on the difference between the planet or black whole from the ring model and which way the arrows point.

Early comments give more likes...😊😊😊

In my opinion this explanation is an elusion as usual. It is true that both speed and gravity slows down time keeping but as it has never been explained how a big mass bends space time more than a small mass without having some kind of influence (force) from the mass I can't see why we might not as well use the old explanation. If you have an oscillating (like a pendulum) electro magnetic signal in any cell, atom or even the smallest particle then if it moves it will take longer for the signal to go from one side to the other and back for the oscillation. This will slow down time keeping. The faster the slower but it is not linear. It is there fore no big deal that if gravity influences light (as I believe has been found although I am still skeptical)) and light is an electro magnetic emission then time should be measured slower in a strong gravitational field. Mahesh is very smooth and fast in his explanations just like a magician. One must take it very slowly, stop often to think about it and then verify and I must admit it is difficult. Albert Einstein must have been the same as many of his explanations supposedly where not even his own.

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!❤️

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 ❤

So Mahesh, when spinning in your ring, the speed varies the farther out you are, but the speed is constant at the point of measurement yes? So you could argue an inertial frame of reference, unless you consider the angular momentum as an acceleration..

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

I love how you explain and use physical examples to explain such complex topic for my finance brain. Love astronomy as a hobby

I’ve heard other explanations about this stuff…but yours seems the best..thank you!!

Didn’t realize the Feynman technique was called that! Whenever I learn something or am doing homework, I try to pretend like I'm the teacher explaining the homework problem to students and it helps me learn a lot more. So yeah, that technique is applicable not just for youtube videos. Try it out if you're struggling in a class

Love how passionate and engaging you are! Your visuals and explanations helped me understand this at a deeper level so thanks🤙

I have a doubt... I don't know whether sir answered it or not anyways I can't find it or understand it(Also, my english isn't that good).... My question is that, space curvature is a visual way to represent objects slowing down due to gravitational time dialation right?..... If so then the curvature i.e, used as a way to visually represent the slowing down of objects, how does that bend the path of light .... According to sir's previous videos it is clear that due to time curvature and surface of a planet accelerating up path of light can be bend near a planet due to "time curvature" but what about space curvature.... How does it bend the path of light?.... That is my question sir😊.....

*PLEASE ANSWER THIS QUESTION* If nothing can escape a blackhole so that means even information cant right?? If yes, then if there is a particle inside the event horizon of a black hole and the particle is entagled with another particle outside of a blackhole it wont able to interact or pass information to it EVEN IF WE DETECTED IT! SO DOES QUANTUM ENTANGLEMENT FAIL HERE or am i wrong?

Please don’t stop making videos, You cure depression.

@Mahesh_Shenoy I have a doubt in your video of train paradox, consider a situation where there is another door/ sensor, before the mid point of tunnel. Then from the train's perspective, the order of doors closing/ sensors receiving messages will be right to left. Now if you look at the same scene with a stationary perspective, you will see that the new door/sensor closes first then the left and right door closes simultaneously. Now let us take the doors/sensors as events 1,2,3 from right to left respectively. Therefore, the order from the train's perspective is 1-> 2-> 3. But from the stationary perspective the order will be 2-> 1=3. So my doubt is that how could the order of events change. Also if there was another train moving opposite to the motion of this train it would see the order of events as 3-> 2-> 1 ( reversed ).

The speed of light isn't a constant; it's more likely that it's the amount of time it takes for a given area of space to process all the things that need to happen. A black hole isn't an infinite dense point in space, it's a powerful energy conversion machine. With more matter/energy you have slower time, which is effectively the frame rate of the universe. The reason light can't escape it isn't due to gravity, it's due to the way energy currents function in space. These energy currents hold the galaxy together, but if there is more energy than can be converted and sent into the galaxy, you'll get a pulsar, which is the method it uses to dump energy. These would be equal to the auroras on the planets. Hope this helps! edit: Aging slower is just a matter of each frame taking longer to process. Going fast means more processing per frame. It's a lot simpler than this mathematical model being described.

Just don't stop to keep building up the intuition videos And I'll ask to even make videos about some other physics topics like i am very in statistical mechanics and quantum mechanics Although I am enjoying the series 😊

Beautiful illustrations! You make this complex subject layperson-friendly!

I think something else is missing in the explanation. Effect of gravity on time in general relativity is applicable only if you “feel” the gravitational force. For example on earth when we feel our weight; if we are in a satellite rotating earth, we will not feel any weight , therefore we are not in an accelerating frame. Same in interstellar: cooper went to a planet rotating a black hole! While in that planet, you will not feel the gravitational force e from the black hole because you are “free falling” ie rotating around the black hole. However, the planet will have to move very fast to stay in orbit of the black hole, therefore special relativity comes in play here. The only time that cooper will really feel the gravitational force of the bacl hole, is when he tried to travel away from it when he will feel a his huge weight inside the space ship. Please let me know if I am thinking correctly or am missing something here.

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?

Mahesh Sir, I'm a big fan of yours. I have 2 physics questions. 1. A piece of ice is floating in a glass full of water. After the ice melts, will the height of the water increase or be equal? 2. Suppose I'm carrying a large stone in a small boat in a swimming pool. If I throw the stone in the pool, will the height increase or be the same as before? By the way, I learned the Archimedes law from your video in Khan Academy. Absolutely amazing!

Hey Mahesh - today I understood how the ground accelerates to meet the apple! Wow man! Check point 4:20

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.

I've had a question I'm hoping you'll address about approaching the speed of light or the event horizon of a black hole. The science communicator channels all seem to agree that when your ship exceeds the speed of light you disappear but they don't ever mention red shifting during the process. It seems to me that it wouldn't be an instantaneous switch from visible to gone, and that after the boundary is reached(supposing it were possible) you would red shift into invisibility as your ship accelerated further. From the point of view of the the ship going into the black hole it would look like the rest of the universe was moving on and aging more and more quickly, I think, and an outside observer would see time slow down and stop for the ship then it would appear to fade into infrared until it became undetectable. What are your thoughts? Edited for clarity*

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?

Ive got a question, if you take a 100 ton metal and a feather and you drop them the 100 ton metal will reach the ground first. If the ground execrates to meet the objects that are falling or whatever why would it be that the heavier item would reach the floor first if the ground would execrate towards the object?

In previous video u said that nothing cannot enter black hole in external absorbers frame the according to an external absorber black hole dose not even exist first blace because nothing as entered the black hole is it sir?? please replay me thank u for the time

7:32. Where is the link? You have not given the link in the description?

Duse, you have such a fresh way of explaining things! I've watched hundreds of science videos, and so many of them repeat the same words as each other, but I'm always thrilled to find a fresh perspective~

You are altering my intuition so fast that I can't stop smiling.

These are so interesting and fun thank you!

I may have already wrote it but you’re as good as 3blur1btown yet in a totally different way when it comes to pedagogy. Bravo monsieur !

Just discovered the channel and while I was watching the previous black hile video, a new one came out. What a coincidence?

Brilliant video - love the channel and your passion for physics!

My village in Uganda is poor. We enjoy your videos. Thank you.

Gravity in general relativity is due to the curvature of space-time caused by mass, not rotation nor velocity like in special relativity. The concept of how much "effort" spent in which dimension, spacial or time, is apt though. The analogy of stopping the rotation to stop simulated gravity does not correspond to how gravity works in reality. General relativity explains that near a massive object, space-time is curved, and this curvature causes time to slow down, a phenomenon known as gravitational time dilation. Gravity is not a force but a curvature of space-time caused by the presence of mass. Objects in a gravitational field follow curved paths, and time passes differently depending on the strength of the gravitational field. Near a massive object, space-time is strongly curved, causing objects in this region to experience a slower passage of time because they are in a stronger gravitational field. Conversely, far from a massive object, space-time is less curved, and objects experience faster passage of time due to the weaker gravitational field. This occurs because, near a massive object, more effort is spent moving through the spatial dimension, leaving less time to tick by in the time dimension. This is similar to special relativity, where increased velocity results in more effort spent in the spatial dimension, causing time to slow down for the moving object relative to a stationary observer. Being stationary near a black hole with no velocity further demonstrates that it is the curvature of space-time, not velocity, that slows time.

The way I imagine it: the center of the circle is the black hole or point or intense gravity, and any circle you draw around the center is a timeline. So, to draw a complete circle, even though it may seem like line physical lines take the same amount of time to be drawn, the "length" of time (the circle) is longer.

There is one problem in the rotating spaceship analogy. Consider a 100 storey building. For a faraway observer, the person at 100th floor will appear to move faster than someone at the first floor, making them think the time of person higher was moving slower, the exact opposite of what we see happening. In another video you showed gravitational time dilation using a bent light beam. That was a better explanation.

Best advice you provided us at the end of the video. I will definitely try it. And I love this video so much. Now I feel satisfied to know this concept 😊

Thank you so much for this. I just watched it with my 10 year old and she now has a much better grasp of gravity and time. I do now as well. ❤

You're the best Physics educator on RU-vid, period

Thank you. Terrific video. I've been saying for some time that spacetime curvature is, in fact simply time dilation. When light travels through space it is always travelling in a straight line from its own point of view and what makes it lens and bend to an observer is in fact time dilation, to keep the velocity of light constant and dilate time to another frame it also passes you effectively curve the distance between them. It's an illusion, spacetime curvature is just a topography of time dilated frames of reference. But this revision of Einstein's explanation using relativistic acceleration explains it much better than I do. Time dilated frames of acceleration reference as topographical gravitation is the term I'll use from now on.

Thanks now I have a better understanding for what time is.

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 ?

"The speed of light is the same in all reference frames, that is why [we have the time dilation effect we call gravity]. Do you now have a better understanding [...]?" No. Like you said, it's like explaining why an apple is red by saying it's a red apple. How does mass cause the path to extend?

Hello Professor Mahesh, I have a question! If Cooper's team brought a camera with them to the planet and were livestreaming it to the space station, what would the video look like from the perspective of the space station?

The model using centrifugal force to describe gravity is very clever, but this model only holds true when the person holding the apple is already standing on the ground and all three body have been combined into one object beforehand, It does not explain the formation of the system. The video you described space-time curvature is what really blew my mind. Even now, I still feel it’s beyond my comprehension.

Your explanations are just simply amazing❤️‍🔥

I don't like that you describe gravity with the parallel to the centrifugal force. Gravity is because space moves towards mass (spacetime curvature) and the ground stops you from moving with space to the center of the planet, Star, black hole. This also means that you are moving relativ to space, not because you are moving but because space is moving and moving objects are time dilated. This is how i understand it and im pretty sure it's true.

This one gets me the speed of light is constant for all observers... time dilation means seconds pass differently so light has to slow down in gravitational field in order to match time dilation so that speed remains the same. And vice versa.

3:49 I cracked up on that silence.

So Mahesh, is the conclusion that gravity doesn't really affect time dilatation, the speed difference due to different positions in the gravity well is the reason for time dilatation?

Saying that „clocks are ticking slower“ makes it soo much harder for laypeople to get it: it’s like saying „the left eyebrow is growing slower“. Everything is happening slower. Causality is slower. Human brains are slower, movements, radioactivity decay, gravitational waves are slower. Not just clocks. Good video though

One of the best explanations of special relativity

I just watch floathead physics just to see how he transitions from the content of the video to the add for Brilliant. I was NOT let down for this one. LOL

Do you mind to share where you got your post-doctoral degrees?

Wouldnt it be easier to simply say that the speed of light is not constant and that light is acted upon by the force of gravity, such that the higher the gravitational pull the slower the speed of light. That would explain the desyncronization of the clocks in a similar way as the displacement model. In other words, the clocks are measuring the time it takes for a particle to go from point a to point b, to make the clock tick slower either increase the distance or decrease the speed of the particle. Relativity posits that we increase the distance, nuetonian physics suggests that we slow the particle.

Very Good intuition. As far as I know centripetal acceleration is another effect different and independent from space-time curvature. In fact we experience both phenomena here on Earth surface and each contribute (oppositely) to the ''gravity pull'' we feel. Nevertheless, the ''time dilation''' effects adds up. When you explain the different time dilation for different observers on a rotating space station from a ''special relativity frame'', for an outside observer, I thought that for relative time dilation to ''occur'' (and length contraction), the motion has to be in the direction of the observer, not sideways. I may be wrong tough

Sir please make a video on the formation of real and inverted images like how they formed on screen, what is screen, how they are inverted etc etc

Very good video!!! One question if I may. The two astronauts on interstellar only felt the gravity from the planet because they and the planet were in free fall around the black-hole so the wouldn't (locally) feel the attraction of the black hole??? I'm having trouble connecting this with "feeling the gravity of the black-hole causes the clocks to slow down..." Any help appreciated!!!

We need more videos like this and less mindless nonsense on this platform. Good on you sir.

it seems so small, but the relativistic effects on GPS satellites are actually HUGE! they would fail so fast without extremely precise programming based on their altitude

There are so many unaddressed realities making the notion of a ship on a surface experiencing slowed time compared to almost normal just a few hundred miles above in an orbit. Even accounting for orbital plane of the craft vs orbital plane of the planet, the planet could never exist experience such a massive shearing of time and space across its own spinning diameter. Plus the was gargantua which had a very gentle event horizon due to its massive size making it more survivable of a black hole to fall into. Assuming it even was a black hole instead of something similar and artificially created for us by future us? The physics of Interstellar were recklessly abusive to physics and did not even try to address these enormous flaws. Still a great movie.