Chethan Krishnan, Lectures on Quantum Black Holes. Lecture 1

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  • čas přidán 29. 08. 2024
  • HE390 - Black Holes, Holography, and Quantum Information
    Instructor: Prof. Chethan Krishnan, CHEP, IISc

Komentáře • 203

  • @mirtehseen4909
    @mirtehseen4909 Před 22 dny +66

    As a student of science it's very complex
    .it's all about imagination
    But the fact is any student who understands this is genius ❤

    • @UROOZFATIMA190
      @UROOZFATIMA190 Před 16 dny +3

      Yeah! as a PCM STUDENT I KNOW SOMETIMES IT IS TRICKY AND very sometimes it's HARD AS WELL..NONETHELESS WHAT I FIND IS THAT THE MORE U GET DEEPER IN THIS THING THEN U FIND THIS as SO SIGNIFICANTLY BEAUTIFUL AND SO COMPELLING TOPICS WHICH UNDERLIES THE DEEP STRUCTURE OF OUR REALITY THAT'S What our REALITY IS ..MOREOVER TO KNOW ABOUT OUR GIGANTIC MYSTERIOUS OBSERVABLE UNIVERSE AND SPACE .. AND UNDERSTANDING THE EQUATIONS MADE ON GREAT THEORIES IS INDEED EQUALLY SIGNIFICANT THING THAT I LIKE (AS A MATHS AND PHYSICS STUDENT WHO LOVE TO STUDY) THESE KINDA COOL STUFF AND WHO LOVE TO IMAGINE THESE THINGS🚀✨

  • @warping_gravity_singularity_0
    @warping_gravity_singularity_0 Před měsícem +267

    Thanks CZcams for suggesting this masterpiece 🔱❤️‍🔥👑

    • @madhavbhamardiwala1606
      @madhavbhamardiwala1606 Před měsícem +2

      Fr.❤

    • @rayanghosh2701
      @rayanghosh2701 Před 29 dny +1

      Exactly

    • @strangobard7885
      @strangobard7885 Před 29 dny +2

      Kya kya benefit huwa tmko isse pura video dekha v kisi nahi kuchh smjh v aaya ki nai ki bs aese hi likh diya masterpiece.

    • @Hfahajayshh
      @Hfahajayshh Před 29 dny +1

      ​@@strangobard7885
      Plss tell me how can u read the mind of commentator just by reading their comment
      U can waste ur time for this lecture ❤
      Rather than wasting for
      Reels🤡

    • @ishitaaaa5134
      @ishitaaaa5134 Před 27 dny +3

      Pehle 9th ka paper toh dedo

  • @sakshikhatak1027
    @sakshikhatak1027 Před 16 dny +31

    I am from a poor village of india .cannot afford education like this .but with help of internet .i am going to to understand black holes and QFT..deeply .

    • @futureshine2715
      @futureshine2715 Před 3 dny +1

      Dear student u have to clean iisc entrance . nothing with poor or rich

  • @seer1966
    @seer1966 Před 18 hodinami +1

    These are excellent lectures. World class and the best of the best. Prof Krishnan is covering very advanced topics with great care guiding the student step by step. I have never seen any Professor address so many student questions in the class with so much patience and still making so much progress in each lecture. The caliber of the students is obvious from the questions they ask. One does not have to be a genius to understand these things. If one has a good physics background and great enthusiasm and hunger to learn these topics, it will be a breeze.

  • @KRISHNA-dt9kx
    @KRISHNA-dt9kx Před 29 dny +87

    this video is not a comedy video, crime video, or an AV yet my eyes are glued to the video that is the beauty of physics and in that "black holes" is an interesting topic

    • @Rumiesque
      @Rumiesque Před 28 dny

      0% naked women
      0% bad words
      0% a$$hole
      100% black hole

    • @dtm2911
      @dtm2911 Před 23 dny +2

      this guy said AV 💀💀💀

  • @messimagic619
    @messimagic619 Před měsícem +116

    I'am not a science student, yet I am watching this lecture.

    • @johnbhai324
      @johnbhai324 Před měsícem +4

      Ohh wow we found Stephen 2.0

    • @messimagic619
      @messimagic619 Před měsícem +4

      @@johnbhai324 Not sure I'm quite at Stephen 2.0 level yet, but I'll take that as a compliment! Just here to learn and enjoy.

    • @mukeshtiwari1095
      @mukeshtiwari1095 Před měsícem +1

      You are just increasing the views on this video😂

    • @mukeshtiwari1095
      @mukeshtiwari1095 Před měsícem +1

      You are just increasing the views on this video😂

    • @messimagic619
      @messimagic619 Před 29 dny +9

      @@mukeshtiwari1095 Guess I'm just here for the free brain workout. Gotta keep these neurons active!

  • @snigdhadas4867
    @snigdhadas4867 Před 21 dnem +7

    Some board, chalk and talk can be interesting if the teacher is adept at capturing attention of students. It's a skill only the best of teachers master in their life..... this teacher constantly speaks sense and connects to students too ...a very nice lecture.... without digitization of this lecture, a middle aged faculty ( specialization in biology) like me wouldn't have got the opportunity to attend this lecture.

  • @NAVEENKUMAR-xl4pb
    @NAVEENKUMAR-xl4pb Před měsícem +39

    Excellent way to experience higher level of knowledge!!

  • @Bollsman
    @Bollsman Před měsícem +291

    2:35 the guy that found pi formula

  • @footballnewscr
    @footballnewscr Před měsícem +19

    thanks for this lectures , we want more lecture as an astronomy enthusiast

  • @shivajidesai5354
    @shivajidesai5354 Před 21 dnem +3

    Quantum theory says the matter exists in small energy packets whose position can't be ascertained.
    Theory of relativity says irrespective of observer's position in space, the speed of light is constant.

  • @Souravjoshvlogsofficial
    @Souravjoshvlogsofficial Před 18 dny +5

    I think this professor know secret of universe 😮

  • @krantiroshansharma3849
    @krantiroshansharma3849 Před 25 dny +11

    Man , I miss chalk board classes .

  • @digdogma
    @digdogma Před měsícem +52

    me who have never even been to school, and look how youtube suggesting me this 😢

    • @stoicR
      @stoicR Před měsícem +1

      Where are you from

    • @zoromarak8039
      @zoromarak8039 Před měsícem +9

      @@stoicRuttar pwadesh, canada.

    • @KRISHNA-dt9kx
      @KRISHNA-dt9kx Před 29 dny

      surprisingly surprised

    • @ashokkumar-id4ne
      @ashokkumar-id4ne Před 28 dny +1

      @@zoromarak8039 phulera,United state of america

    • @KPISEASON353
      @KPISEASON353 Před 26 dny +2

      Why you never went to school?? Very few people do that in the world

  • @Souravjoshvlogsofficial
    @Souravjoshvlogsofficial Před 18 dny +1

    I thank to youtube here for suggesting me this lecture 😊

  • @hrmg24
    @hrmg24 Před 23 dny +7

    Knowledge isn't free,you have to pay attention

  • @Hero007ization
    @Hero007ization Před 19 dny +4

    I wish my college professors could teach this way !

  • @aadityapratap007
    @aadityapratap007 Před 25 dny +6

    This is what I crave for.

  • @natureatitsbestplace
    @natureatitsbestplace Před 28 dny +16

    With due respect to the Revered Teacher, thanks for your efforts.
    But There are many ways by which you can make this so confusing topic , intresting.
    1) Integrate visuals,digital medium, virtual reality,etc.
    2) It would be great if you take some preliminary extra lecture on prerequisites, this will easy your burden of future sessions, and help students a lot.
    3)Sorry to say , but you yourself need some more clarity on the topic, expected doubt and questions. Discussions on this topic is generally full of questions, answers and then counter questions but here students are so confused that they don't know what's the correct question.
    4) Aim of each lecture and its out come must be clearly stated.
    5) Instead of writing on board,it would be better to use systematically arranged slides with respective examples, limitations, assumptions,etc.
    This will helpyou to cover all the related topic without missing or forgetting any and will help students clearly understand.
    ....
    ....
    IISc is the great place and so do there teachers. You are the True Krishna for the comming generations Arjuna....!!!!🎉🎉🎉🎉🙏🙏🙏🙏

    • @Universon-wi7mx
      @Universon-wi7mx Před 25 dny +3

      were you one of the students there,
      Are you a physics professor That teaches in prestigious institutions like iisc.
      You actually have no right to tell him all this

    • @comptech5240
      @comptech5240 Před 24 dny +8

      @@Universon-wi7mx why. he is a student and has utmost right to get quality education whatsoever. Stop with this conservative attitude of never questioning someone's ways. No respect is lost as such, instead if the teacher is good, he/she would feel that the student is invested in the topic and hence wants it better delivered

    • @Universon-wi7mx
      @Universon-wi7mx Před 24 dny

      @Gautam-p3l 😇

    • @Universon-wi7mx
      @Universon-wi7mx Před 24 dny

      @@comptech5240 Sorry if I was offensive, but studied there, from the same teacher once. He was good. I just shared my point of view.

    • @comptech5240
      @comptech5240 Před 24 dny +2

      @@Universon-wi7mx no harm done. Just wanted to state a point 😃

  • @aniket31415
    @aniket31415 Před 27 dny +9

    I'll join IISc banglore next year for sure❤

  • @shyamasundar8820
    @shyamasundar8820 Před 20 dny +2

    Iisc is premere institute. But compare to other CSIR laboratories it is doing lot of work in basic and applied science.

  • @venomousshooterrony5405
    @venomousshooterrony5405 Před 10 dny +1

    See how calm the environment is unlike a third class private college class where a professor will give you at least 10 minutes lecture on being late in the class even by 30 seconds 😅

  • @msobert4
    @msobert4 Před 21 dnem +2

    wanted to involve in this type of programs , hope can do this in next life only

  • @RishiRaj-bl8yx
    @RishiRaj-bl8yx Před 7 dny +1

    28:10 sir you have written the Schwarzschild's solution wrong there should be c^2 in multiplication with dt^2

  • @Gauravkr0071
    @Gauravkr0071 Před 6 dny +1

    i am a software engineer , but still for fun i am watching this.

  • @mitheshpatel6806
    @mitheshpatel6806 Před 24 dny +1

    Thanks utube fr suggesting this

  • @naveenbhatt4745
    @naveenbhatt4745 Před měsícem +2

    masterpiece lecture sir

  • @iamnotcaptainyt4953
    @iamnotcaptainyt4953 Před měsícem +9

    Bro if i had time and the understanding of all the prerequisites i would just watch all the lectures , understand them and spend life solving those equations

    • @muthuselvi9556
      @muthuselvi9556 Před 25 dny +2

      Damn dude, same!!

    • @Souravjoshvlogsofficial
      @Souravjoshvlogsofficial Před 18 dny

      Life is short use it smartly. No one no about black hole completely. We will end up with confusion in the end as you start deep dive into the concept.

  • @Rakeshsadhu007
    @Rakeshsadhu007 Před měsícem +17

    iiserssss❤

  • @ChannabasavaGouda
    @ChannabasavaGouda Před 28 dny +3

    Prof explantion been like Inbuilt x2 speed

  • @anshul021
    @anshul021 Před 20 dny +1

    like how he say 'generalativity'

  • @PankajKumar-vi6rp
    @PankajKumar-vi6rp Před 14 dny

    Great lecture.❤

  • @himanshudixit5711
    @himanshudixit5711 Před 14 dny

    All Hail CZcams algorithm for the recommendation. ❤😍♥

  • @newaccount-cz6tb
    @newaccount-cz6tb Před 22 dny +1

    I have quite an interest in physics and chemistry. I think i can contribute to the country but i am confused about my career paths. Is doing research in this specific field in india is worth it. Will the amount i will earn sustain me and my family. This was my question and i hope i find some answers from seniors present here

  • @higherbeingX
    @higherbeingX Před 23 dny

    "CHEP IISc" - you should expand this for global audeince

  • @user-og2lt8ou8i
    @user-og2lt8ou8i Před 27 dny +4

    I don't understand, why these students are coming late being in this prestigious institute? Missing introductory premise for the further study... Institute must take some measure!

    • @BiologicArrow4
      @BiologicArrow4 Před 25 dny +4

      Bhai, they are iisc students, I think they know some basic of their subject

  • @Notsoperfectshrikant
    @Notsoperfectshrikant Před měsícem +17

    Professor, why are we having variables applicable in local system(known environment such as Earth and some millions of kilometers around Earth) on unknown system(I don't know whether it should be called a system, the black hole I mean). BTW, I am no way related to Quantum world and astro bodies' studies.

    • @Lonewolf123go
      @Lonewolf123go Před měsícem +5

      Then why are you here ?

    • @Notsoperfectshrikant
      @Notsoperfectshrikant Před měsícem +26

      @@Lonewolf123go such warm welcoming response, thank you!

    • @henlo5453
      @henlo5453 Před měsícem +5

      because aak is pak, pak is aak so aak pak karepak

    • @letstrytodoit
      @letstrytodoit Před měsícem

      😂😂😂😂​@@henlo5453

    • @manuupadhyay1635
      @manuupadhyay1635 Před 23 dny +1

      I apologize on the behalf of the replies to your (a very good) genuine query. You see, the physical laws being invariant under coordinate/frame transformations is one of the many suiting assumptions that we make before going on to formulate theories to explain some very specific phenomenon observed in the labs or telescopes. This way, we get a framework through which we can study general phenomena or hypothesize experiments, observe results and verify or revamp the existing theories. Most of the times, these theories, with their reasonable assumptions, conform to the experiments/observations with very less deviations and they go on to become the guiding beacon for our future understanding of various other events!

  • @VolatileGuy103
    @VolatileGuy103 Před měsícem +9

    why am i here and how did i understand everything he said.
    ps- i am an MCA student

    • @akshu9934
      @akshu9934 Před 24 dny

      same here, an mca student ended up here while watching a leetcode problem lol

  • @DimasaKing
    @DimasaKing Před 23 dny

    I wish this vid never reaches Gen Asthana. Or this will figure in next SMT update😢😢

  • @VRAJCHAUDHARY-b9r
    @VRAJCHAUDHARY-b9r Před měsícem +4

    can it be an catastropic event 54.20

  • @AgastyaSharma-h9b
    @AgastyaSharma-h9b Před 25 dny +4

    as a JEE aspirant, giving the exam in 2025, this blows my brain to a different extent, like above the jee adv level

    • @I_am_Dipanjan
      @I_am_Dipanjan Před 25 dny +8

      Please learn how to think beyond JEE brother. This education system has corrupted your mind to become oriented into just problem solving like a computer. I wish you well.

    • @manishsingaria3895
      @manishsingaria3895 Před 25 dny

      Are you comparing everything with jee advance ? Thing is jee advance level is similar to what you will get to study in first 2 year of graduation in engineering/bcs physics/ bsc chemistry.

    • @I_am_Dipanjan
      @I_am_Dipanjan Před 24 dny

      @@manishsingaria3895 Not even first 2 years bro. I am a 3rd year BSc Physics student and JEE adv. became bread and butter for me after the 1st year of BSc.

  • @hassanmirza2392
    @hassanmirza2392 Před 16 dny

    Hello and Thanks from Pakistan.

  • @aryamangogoi6764
    @aryamangogoi6764 Před 26 dny +3

    This lecture is for which year student at IISc?? it is UG or PG class?

    • @GuzzarAwan
      @GuzzarAwan Před 24 dny

      I dont think IISC has any UG courses

    • @aryamangogoi6764
      @aryamangogoi6764 Před 24 dny +2

      @@GuzzarAwan update yourself, it seems you are still living in pre 2011 era.

  • @afsarrashid2967
    @afsarrashid2967 Před 26 dny

    Thank you...❤❤❤

  • @vaibhavsingh4555
    @vaibhavsingh4555 Před 28 dny +4

    2:42

  • @eshangarg9031
    @eshangarg9031 Před měsícem +8

    instead of propounding the concepts like this it is better to involve the students and discuss and discover the concept with them walking them by hand. Not many geniuses can born through the way education is taught now in our country

    • @adityapanda_2000
      @adityapanda_2000 Před měsícem +8

      I think you don't know what kind of students study there. India's best top 50 are only able to make it to iisc

    • @Kabir82633
      @Kabir82633 Před měsícem

      @@adityapanda_2000 top 50 huh

    • @bossdom1997
      @bossdom1997 Před měsícem

      ​@@Kabir82633ya

    • @subhamdas3731
      @subhamdas3731 Před měsícem +4

      It's a PhD level course given in the world's no1 research Institute and you need a decent understanding of the prerequisites to understand it. In this lecture, he was simply using the prerequisites to explain certain facts.

    • @starshine3702
      @starshine3702 Před měsícem +1

      That is done in lower classes where hands-on experiences are given priority over lecture methods.
      What are you expecting here lol most of the topic here is abstract untill it gets proved what do want professor to do lmao

  • @karthikcind1981
    @karthikcind1981 Před 21 dnem

    Is this chetan krishnan who studied at loyola school Trivandrum??

  • @mohitanandjaiswal9293
    @mohitanandjaiswal9293 Před 26 dny

    Please dont laugh at my question, i am a student of arts and very weak at maths, but i have always been curious in black hole, time machine etc can i watch this? Or i should give up..

    • @sujathaontheweb3740
      @sujathaontheweb3740 Před 25 dny +3

      Why limit curiosity? Maths doesn't have to come in the way of pursuing what you're curious about. It's not like you're making it your profession. Enjoy the other world, and don't let Maths scare you! Have fun! 😊

  • @LMAO_106
    @LMAO_106 Před měsícem +1

    The reason i want to go to iisc

  • @AdarshGupta-hc3qv
    @AdarshGupta-hc3qv Před 2 dny

    why blackboard is same as in 3 idiots movie

  • @TrEndsmr588
    @TrEndsmr588 Před 26 dny +11

    Don't know but this board is looking like the 3idiots ones .
    If agree like😅

  • @aritradubey1790
    @aritradubey1790 Před 26 dny

    Ram Ram🙏🕉

  • @texastexas4541
    @texastexas4541 Před 15 dny

    Why does he speak so fast? I can't understand half of what he says. Is Blackhole mentioned in the Vedas?

  • @yottahertz
    @yottahertz Před 22 dny

    What camera is used to record this ?

  • @CatchMe-pt4ej
    @CatchMe-pt4ej Před 10 dny

    Explanation is ok ,but need to go more into the subject rather than briefly on unwanted things 😉

  • @UmangBhardwaj-y6u
    @UmangBhardwaj-y6u Před 21 dnem

    Which sem is thim I am in BSC 1st sem at amu
    I can't understand anything

  • @samuelwesley668
    @samuelwesley668 Před 22 dny

    is this an undergrad or masters class?

  • @nothing.to69
    @nothing.to69 Před 24 dny +1

    DO you hindi lectures on qunatum blach holes

    • @iagreewithyou4328
      @iagreewithyou4328 Před 23 dny

      How shame!ess can you be to ask this?

    • @pollyaich4559
      @pollyaich4559 Před 18 dny +1

      ​@@iagreewithyou4328 wtf is wrong with u? go outside sometimes dawg

  • @littlelilly7480
    @littlelilly7480 Před 21 dnem

    CZcams algorithm is actually crazy

  • @nischals.g1323
    @nischals.g1323 Před 21 dnem

    what course in iisc is this

  • @dsrawat267
    @dsrawat267 Před 7 dny +1

    Walking here and there is irritating.

  • @sachin7488
    @sachin7488 Před měsícem +27

    this is what we should watch and enjoy rather than religious bullshit babas in this country

    • @itachiofthesharingan67
      @itachiofthesharingan67 Před měsícem +11

      That’s a separate issue, and religious preachers can be found in every country, not just one. It’s your choice what you choose to watch.
      The definition of enjoyment varies from person to person, so do you think a farmer or a chef would find this enjoyable?

    • @starshine3702
      @starshine3702 Před měsícem +8

      We can be religious and we can also love science they are not entirely interconnected.

    • @Aryanthemystic
      @Aryanthemystic Před 29 dny +12

      Last time I checked, all of the Nobel prize winners of india were Brahmins the priest class the great scientists 😂😂😂

    • @sunny123k
      @sunny123k Před 29 dny +1

      ​@@AryanthemysticLast time I checked, the majority of the Nobel Prize winners were Jews, the original monotheists. So, what's the point?

    • @sunny123k
      @sunny123k Před 29 dny

      ​​@@AryanthemysticLast time I checked, the majority of the Nobel Prize winners in the world were Jews, the original monotheists. So, what's the point?

  • @Chiavaccio
    @Chiavaccio Před 24 dny

    👍👍

  • @suvadipmazoomder28
    @suvadipmazoomder28 Před měsícem

    ❤❤❤

  • @satyadevmodali9068
    @satyadevmodali9068 Před 29 dny +1

    What are the prerequisites for this course?

  • @niraj_nerd
    @niraj_nerd Před 18 dny

    135k views hmmmm so i feel everyone understands Black holes now>?

  • @rajat23ranjan
    @rajat23ranjan Před 26 dny +1

    the girl at begining walking

  • @caikayee
    @caikayee Před 27 dny +1

    Noice 🦀

  • @Positivity-u6c
    @Positivity-u6c Před 26 dny

    Vedio ka topic sahi hai lekin ise ese angle par rakhe jisse keval sir dikhe ate jate student nahi

  • @ramachandrannarayanan6997

    Dear Sir, u r not "a faculty".( 'faculty' is plural.)
    U r a faculty member.
    Pl. tuck in ur shirt. Be formal in dressing and set a good example.
    U r not walking in a park.
    Pl. don't take it amiss.

  • @RomitChavan-wj8lu
    @RomitChavan-wj8lu Před 7 dny

    why can't he stand still

  • @xdfckt2564
    @xdfckt2564 Před 23 dny

    You HAVE to have that IISc t shirts dont you 😂

  • @ArvindKumar-rl7vs
    @ArvindKumar-rl7vs Před měsícem +23

    I cant understand his speech

    • @jrntrfanboii
      @jrntrfanboii Před měsícem +1

      he is a mallu

    • @Auxxxin.14
      @Auxxxin.14 Před měsícem +3

      He is South Indian use earphone with good sound then you will understand easily

    • @johnbhai324
      @johnbhai324 Před měsícem +2

      @@ArvindKumar-rl7vs actually u don't need to..

    • @NataNata-ur5bf
      @NataNata-ur5bf Před 29 dny

      ​@@johnbhai324 💀☠️

    • @cakewalk4602
      @cakewalk4602 Před 26 dny

      I'm from Ny i can clearly understood his pronounciation and what's he's teaching maybe it's just a *you* problem. my advice take more english classes or listen to more audiobooks.

  • @anoopak2839
    @anoopak2839 Před 8 dny +1

    Its too irritating for me that while delivering lecture he is walking left and right in front of the board. Any other felt the same?

  • @vedangastrology533
    @vedangastrology533 Před 10 dny +1

    This is not way to teaching

  • @shepherdamedegunu3675
    @shepherdamedegunu3675 Před 21 dnem

    I don't know why am watching this

  • @mishrajyoti2828
    @mishrajyoti2828 Před 8 dny +2

    This classroom look like 3 idiots classroom ....

  • @sureline_
    @sureline_ Před 19 dny

    why the heck I'm watching this

  • @yuvrajsharma5956
    @yuvrajsharma5956 Před 27 dny +9

    The worst thing I realized today is even IISc Banglore is so absured & outdated to use chalk & board system in 2024😢

    • @streetfoodexplore9910
      @streetfoodexplore9910 Před 26 dny +17

      Even in MIT they use chalk and board.Don't be amused.

    • @lakshya9612
      @lakshya9612 Před 26 dny +7

      Bro mit also use chalk , they also absured

    • @GuzzarAwan
      @GuzzarAwan Před 24 dny +3

      well , some profs love to use chalk and board more than marker. Also these institutions r so good in india like ISRO IIT IISC bcoz they r RUN by Profs not IAS/PCS or administrators , the Profs in various position also get big discretion on decision-making even then u wont see any corruption charges , and Optimum use of Funds.

    • @anubhabchatterjee4403
      @anubhabchatterjee4403 Před 24 dny +1

      Knowledge matters bro....
      Chalk and duster is the best way to present....

    • @aethist-ns6gv
      @aethist-ns6gv Před 23 dny +2

      Much much better than scrolling through powerpoint slides. Chalks are better than even markers and are still widely used in even ivy league colleges.

  • @martinpmaniputhenpurackal

    This lecture may be from Kerala i guss

  • @olegsblog
    @olegsblog Před 24 dny

    Complete lack of discipline.
    Students are constantly walking.
    The teacher speaks very fast, like a tongue twister. Lack of visual aids.

  • @namanpatil4016
    @namanpatil4016 Před 24 dny

    I dont like your teaching style.

  • @venkatarr
    @venkatarr Před 25 dny

    This guy must be from non reservation background. This quality delivery possible only for them.

  • @AritraAcharya-vl6hf
    @AritraAcharya-vl6hf Před 21 dnem

    2:35