the most famous Ramanujan sum 1+2+3+...=-1/12

Sdílet
Vložit
  • čas přidán 27. 12. 2018
  • What is the sum of all the natural numbers? Isn't it just infinity or is it really -1/12? Here we will see 1+2+3+... "will be" -1/12 if you use the Ramanujan summation, which is a way to assign a value to a divergent series.
    Check out Bose Integral: • Zeta function in terms...
    Check out NOT -1/12, • Not -1/12
    Sum of 1/n^2 by a Gucci Integral: • a spectacular solution...
    Sum of n^2, • how Ramanujan did 1^2+...
    Ramanujan Summation: en.wikipedia.org/wiki/Ramanuj...
    Ramanujan summation in detail: hal.univ-cotedazur.fr/hal-011...
    The sum of all natural numbers:
    by 3b1b: • But what is the Rieman...
    by Numberphile: • ASTOUNDING: 1 + 2 + 3 ...
    by Mathologer: • Ramanujan: Making sens...
    🛍 Shop my math t-shirt & hoodies: amzn.to/3qBeuw6
    💪 Get my math notes by becoming a patron: / blackpenredpen
    #math #mathforfun #blackpenredpen #calculus #ramanujan

Komentáře • 758

  • @Nondas8552
    @Nondas8552 Před 5 lety +3252

    When you have to prove that the sum of all natural numbers equals -1/12 at 10 pm and go on a date at 11 pm

    • @blackpenredpen
      @blackpenredpen  Před 5 lety +585

      Yup!! : )

    • @leif1075
      @leif1075 Před 4 lety +37

      @@blackpenredpen isnt it only true if you include inaginary numbers like negative one square root..otherwise it is impossible and incorrect! Because the sum,always increases..

    •  Před 4 lety +8

      @@leif1075 If you taking the sum of all counting numbers from one to infinity then your sum is already increasing continuously.
      What controversy on this integral sum!!

    • @johnny_eth
      @johnny_eth Před 4 lety +67

      It's not equals. The sum is divergent. The Ramanujan summation is a transform that assigns values to divergent series. Kind like how a Fourier transform gives you the domains of frequencies and phases of a periodic signal but it NOT equal to the signal.

    • @19divide53
      @19divide53 Před 2 lety +9

      @@johnny_eth The equal in OP's comment is obviously in a Ramanujan summation sense

  • @badmanjones179
    @badmanjones179 Před 5 lety +980

    black pen red suit

  • @alanturingtesla
    @alanturingtesla Před 5 lety +978

    Square root of -1‚ now convergent-divergent series. In a few years, I expect dividing by 0.

    • @tricky778
      @tricky778 Před 4 lety +63

      @Alan Turing, which size of 0? a big 0 or a little 0? I'm sure if you divide by a big 0 you get a smaller result than a little 0

    • @arnavanand8037
      @arnavanand8037 Před 4 lety +60

      I feel like for that we need to redefine division. Just like there's gamma function for factorials

    • @GynxShinx
      @GynxShinx Před 4 lety +18

      lim(x->0+) 1/x->infinity
      If you're too lazy to write the whole thing then 1/0+=infinity

    • @arnavanand8037
      @arnavanand8037 Před 4 lety +20

      @@GynxShinx I think everyone knows the limit already. But people feel unsure about the actual answer

    • @oracle7858
      @oracle7858 Před 4 lety +4

      Eagle Shows Down 1/0+ is infinity but what is 1/0 🤔

  • @radiotv624
    @radiotv624 Před 5 lety +560

    This is fascinating, I love Ramanujan

    • @kingbeauregard
      @kingbeauregard Před 5 lety +32

      Me too, especially the chicken-flavored stuff.

    • @davidrheault7896
      @davidrheault7896 Před 5 lety +13

      The monster is back again...i know it from physics waves in vacuum. -1/12 casimir effect

    • @radiotv624
      @radiotv624 Před 5 lety +2

      David Rheault That’s right! What is/was your major

    • @davidrheault7896
      @davidrheault7896 Před 5 lety +2

      @@radiotv624 I did a specialisation in physics
      It is above major.

    • @indicgamer2907
      @indicgamer2907 Před 5 lety +22

      Ramanujan's work opened a new world of mathematics that astrophysicist use to study black hole , time travel , free energy quantum tunneling

  • @moumous87
    @moumous87 Před 3 lety +48

    2:00 you got to love this guy for putting the R on top of the = and for actually showing what the heck is this "Ramanujan summation" thing. Thank you

  • @themeeman
    @themeeman Před 5 lety +413

    Looking sharp

  • @dayzimlich
    @dayzimlich Před 5 lety +77

    One of your best videos yet - keep up the great positive attitude in 2019!

  • @benjaminbrat3922
    @benjaminbrat3922 Před 5 lety +38

    Thank you very much for this much-needed relativism when talking about divergent series. You could go even further by presenting several alternative summations (Cesàro, VP, Lambert, Borel, etc), I know Cesàro to be quite easy to grasp, and this would contribute bringing diverging sums enough breathing room for actual exploring, instead of bantering. Happy New Year!

  • @YourPhysicsSimulator
    @YourPhysicsSimulator Před 5 lety +98

    So elegant... I'm talking about you, though.

  • @saxbend
    @saxbend Před 5 lety +375

    Mathologer wants a word.

    • @NateROCKS112
      @NateROCKS112 Před 5 lety +91

      Mathologer actually hinted at what is going on in this video. He showed that the area under the x-axis of f(n) = n(n+1)/2 is -1/12, which can be interpreted as a definite integral from -1 to 0 of n(n+1)/2. n(n+1)/2 is a graph of this infinite series (as n→∞) since it's the sum of all natural numbers up until n.
      Also, BPRP used the proper notation with the Ramanujan summation, and did not claim that the natural numbers "summed" to -1/12, just that they could be assigned to it.

    • @angelmendez-rivera351
      @angelmendez-rivera351 Před 5 lety +103

      NateROCKS112 Mathologer did show this, but he equally also spoke against any association between adding the natural numbers and obtaining the result -/12 via analytic methods.
      The problem lies in how poorly and inconsistently the technical terminology of calculus is being used, and how poorly the word “summation” is interpreted. The problem is that, nowadays, when dealing with sequences of partial sums, we tend to associate them to summations themselves, without much justification, even though these summations are not sequences, but numbers, and the summations are furthermore the result from a set of rules of arithmetic operations on a field, whereas statements about these sequences are statements about vector spaces and linear functionals.
      When we see the sentence 2 + 2 = 4, this statement is provable. This has nothing to do with sequences. It is a statement that is the consequence of the rules of addition and basic arithmetic. When we see that f(x) = x^2, and we calculate f(1) + f(2) + ••• + f(100), this is also a statement about arithmetic, and summation notation is merely a notation to abbreviate this result: the operation is ultimately still addition. I see no reason why 1 + 1/4 + 1/9 + ••• = π^2/6 should be treated any different. In fact, to prove this identity, we typically just use algebra and trigonometry, not much from calculus itself though. I see no reason why 1 + 2 + 3 + ••• = -/12 should be treated any different either. Caught hated the concept of infinity. He was, so to speak, an ultra finitist. This is why he invented the concept of a limit, and whenever we wanted to speak of adding infinitely many numbers together, he rejected the idea, and instead proposed to talk about the limit of the sequence of partial sums. For some practical purposes, and for his specific theoretical, both mathematical and philosophical purposes, this definition works just fine. Nowadays, we treat it is a method to assign value to infinite sums, but strictly speaking this method does not give you the sum itself. In fact, as I already said, Cauchy would have said such sums do not exist, and the expressions are nonsensical, precisely because he did not believe in the notion of infinity. So associating actually adding infinitely many terms with these limits is conceptually incorrect, and an equivocation of bounded behavior with infinite quantity, which should not happen. What the limit of the sequence of partial sums tell us is information about the asymptotic behavior of some function, and this function represents an algorithm. In the case of the natural numbers, what this limit does is answer the question, “What happens when, at every step of some process, I add the next natural number to the total I already have?” It tells us that this process will result in a number which at every step is larger than it was before, and at an increasing rate. I am not succeeding in getting closer to some value when I do this process. This is the proper meaning of what divergence is for this case. This tells us nothing about ACTUALLY adding the natural numbers, which intuitively and arithmetically should have nothing to do with sequences (because if we defined addition by sequences, it could never be commutative or associative, but we know addition is a commutative operator for fields). In fact, it tells us nothing about adding infinitely many numbers in general in the first place. We make the association because we want to and because it is practical in some contexts, but again, they strictly are not the same thing, especially when you understand the mathematical logic behind the axioms and definitions. Obviously, mathematicians tend to understand this, but when students learn calculus, they do not learn any of the rigorous details behind the definitions or theorems involved, so naturally they get confused.

    • @Lolwutdesu9000
      @Lolwutdesu9000 Před 5 lety +4

      @@angelmendez-rivera351 this is a brilliant post.

    • @literatedouchebag
      @literatedouchebag Před 5 lety +7

      @@angelmendez-rivera351 i couldn't have said it any better. Amazing post my dude

    • @angelmendez-rivera351
      @angelmendez-rivera351 Před 5 lety +8

      VeryEvilPettingZoo “But it’s the only definition that makes any conceptual wrong.”
      And that’s obviously wrong, as mathematicians from the 17th century have proven with their understanding of divergent series, which literally preceded any understanding of limits of sequences. The fact that surreal numbers and transfinite addition exists, without need to use limits and all, further proves this point. You must know any mathematics beyond those of your calculus II textbook if you think it’s the only conceptually sensical definition.
      But the other reason you are wrong is because there is no such a thing as “the ordinary conceptual understanding” of something in mathematics. That doesn’t exist. Mathematics is strictly and exclusively about what axioms you work with. And depending on the axioms, something is true, or it isn’t. And here is the catch: there is no standard set of axioms that is used in every field of research. Even within the same field of research, if we are having a conversation and I decide to get a different level of rigor, even there we’ve already changed the scope of the axioms and of the theory. Because of this, there is no ordinary understanding of anything: any understanding of anything just comes from axioms and that’s that. Math has nothing to do with intuition, and because of this, nothing is ordinary or conventional. That is what people refuse to understand. The only reason some things seem conventional to some people is because they’ve been limited to only specific math courses or they were exposed to something first for the longest time before being taught something they personally would consider “non classical”. If you had been raised with a calculus course learning about Ramanujan summation first and then being exposed to it continuously to work with it in engineering for the rest of your life, then you would perceive that to be the only conceptually ordinary sense to add infinitely many things. But that too would be an illusion. If there were such a thing as an ordinary conceptual understanding, then it wouldn’t be necessary to learn maths in such a way that in every new course, everything you learned previously is a lie and that there is another way to look at things. And look: mathematicians said the exact same thing about complex numbers centuries ago. The fact that people continuously make these claims and centuries later are always disproven is an obvious indication to the fact that such ideas about understanding are subjective and merely illusions, artifacts of tradition, not real in any mathematical or logical sense.
      “...of what it would mean to add up the terms of that series “forever”.”
      There is no such a thing as adding things up “forever” in mathematics. I don’t care if you put it in quotation marks or not: that word should not be in that sentence, not even in a remote, metaphorical sense. You’re projecting feelings and intuition that don’t exist in mathematics into the subject. Adding infinitely many numbers does not have anything to do with time. If I add one by one, then yes it would take me a very long time to finish the process, mechanically speaking, but processes don’t define anything in mathematics. If we can agree that a sum of infinitely many numbers can have a value, then that has nothing to do with time. Talking about time only furthers the misconception about what infinite sums represent notionally. If I have a way of adding infinitely many numbers and knowing what that is, then in principle there is no reason I shouldn’t be able to do this immediately, in less than a picosecond, or faster. And if time was of relevance, then it would be impossible to talk about infinity in the first place, so the concepts of convergence and divergence would make no sense whatsoever.
      “Conceptually, it’s indisputable that adding up the series “indefinitely” drives the sum up towards infinity, not -1.”
      And once again you made the mistake I pointed out in my comment. It’s like you just missed my point altogether. If you have a sequence defined by steps, where in every step, you add the next natural number, then yes, you get a process by which this number will increase to infinity as more and steps are performed, arbitrarily. And unfortunately for your argument, that’s NOT what the sum itself is. Summation is an operator, not a process. Nothing in mathematics in any field is a process. The only field in mathematics that talks about things related to processes may be some subfield of discrete mathematics concerning computing power and what not. But those things don’t define operations, nor should they. A mathematical identity and the process you get by it computationally are strictly unrelated. Perhaps children have a strong association between operations and processes, because it’s the only exposure they’ve ever had of operations, since they cannot really understand the abstract essence of what operations are, but that’s it. If I can add all the powers of 2 at once, then there is no “driving the sum” anywhere because there is no process, there is no sequence. Any extension of an operation should capture this abstract essence of what the operation is rather than any false non/existing notion of a procedure. You can choose to create a mathematics which is based on procedures, maybe define something call procedure theory. But that wouldn’t be arithmetic of real numbers anymore, that would be, well, procedure theory.
      And worse for the argument is that this concept of limit to infinity depends strictly on the type of infinity you are choosing to use as a boundary condition on the real line. Calculus on the projective line looks very different. Which only proves my point further.
      I will watch the video, though I hardly doubt they’ll say anything fruitful I haven’t already addressed, unless they end up agreeing with me. I say this as I’ve been in over 50 different discussions about the subject.

  • @angelmendez-rivera351
    @angelmendez-rivera351 Před 5 lety +224

    The discrepancy between saying that the series diverges and the sum is -/12 is that they are not even talking about the same thing. The fact that it diverges is a statement about asymptotic behavior and sequences, whereas the latter is a statement about arithmetic and infinite sets. Calculus is a theory about sets and functions. When we deal with summations in calculus, we never truly deal with an infinite summation, so to speak, although we do call them this out of bad tradition (just like how calling imaginary numbers imaginary is bad tradition). In calculus, what we do deal with instead is sequences of partial sums. Why? Because this tells us about the algorithm of after one number after another. If I start adding the natural numbers, in a specific order, and form a sequence for every step, then what is the behavior as I increase the number of steps? The behavior is that this sequence simply becomes infinite, every number I get is larger and larger on several orders. Although we tend to associate this with adding infinitely many terms, this is not what is truly happening and is merely an informality that happens in the calculus classroom, since explaining the real details behind standard analysis is complicated and outside the scope of the syllabus. In a sense, using the limit of the sequence of partial sums is already a way of assigning values to infinite series. It already is “a summation method”, but it is an error to call it a summation in the arithmetic sense because it obviously is not, since it has very different properties.
    This bears no contradiction with what Ramanujan postulated because Ramanujan is not talking about sequences and their limits. What Ramanujan is trying to do instead is imitate more closely the properties of summation as given by number arithmetic. Naturally, since we are adding elements of infinite sets, the results we produce are counterintuitive and outside of what induction can allow us to prove.
    Keep in mind, though, that using Ramanujan summation is not the only way to arrive at this result. Abel summation and Borel summation are both more intuitive than Ramanujan summation, and they also give -/12 as a result. Also, here is an interesting article by Terrence Tao that justifies this non-classical result in a very convincing way. terrytao.wordpress.com/2010/04/10/the-euler-maclaurin-formula-bernoulli-numbers-the-zeta-function-and-real-variable-analytic-continuation/#zeta-s
    One thing I find interesting is that the integral from -1 to 0 of x^2/2 + x/2 is 1/6 - 1/4 = 2/12 - 3/12 = -1/12. It is interesting because this integral is the area between the x-intercepts of the function f(x) = x^2/2 + x/2 = x/2•(x + 1), which is equal to the nth partial sum of the sequence of natural numbers for x = n.

    • @user-ft2vp5yw6p
      @user-ft2vp5yw6p Před 5 lety +7

      Wow, just wow. Amazing

    • @DarthRaven9000
      @DarthRaven9000 Před 5 lety +15

      Very well written. This clarifies what seems contradictory when the topic is usually discussed without a proper perspective. Thank you.

    • @DanNguyen-oc3xr
      @DanNguyen-oc3xr Před 5 lety +3

      "Naturally...counterintuitive." Damn it.

    • @suprafluid3661
      @suprafluid3661 Před 5 lety +1

      @@DanNguyen-oc3xr But i was going to say that hmmm.. 😣

    • @abustefano8225
      @abustefano8225 Před 4 lety

      Mmmm... Something wrong here.
      According to Abel-Olana formula en.m.wikipedia.org/wiki/Abel%E2%80%93Plana_formula the series diverges.
      Please elucidate

  • @elthomaso10
    @elthomaso10 Před 5 lety +14

    This is hands down the most terrifying video title I've ever seen.

  • @biswadeepghosh5568
    @biswadeepghosh5568 Před 5 lety +18

    Great presentation, felt so good since this concept is related to the work of Ramanujan, many thanks to help me understand this concept.

  • @fCauneau
    @fCauneau Před 5 lety +3

    That's what I call a Christmas gift ! Thanks !!! And Merry Xmas to you and your readers !!

  • @spudhead169
    @spudhead169 Před 2 lety +80

    Thank you, both Numberphile and Mathologer didn't really explain this properly, that it's a "non-canon" summation.

    • @rykehuss3435
      @rykehuss3435 Před 4 měsíci

      Nice way of saying its just made up by Ramanujan to goof around with

  • @user-po9yn4ni4u
    @user-po9yn4ni4u Před 5 lety +88

    or you should say the zeta(-1) is -1/12

    • @abhiruppaul5601
      @abhiruppaul5601 Před 3 lety +2

      correct bro

    • @arnoldo-probjeto3111
      @arnoldo-probjeto3111 Před 2 lety

      Not correct bro. In fact, ACzeta(-1)= -1/12, where ACzeta is the analytic continuation of zeta function, that is NOT the zeta function.

    • @19divide53
      @19divide53 Před 2 lety

      @@arnoldo-probjeto3111 But we call the analytic continuation of zeta function by ζ(s) as well. A bit of abuse of notation but I think that's the convention. In fact, in Riemann's 1859 paper he did denote the analytic continuation of zeta function (sum of n^(-s) over all positive integers n) ζ(s), which you can see by looking at the paper online.
      There's no reason to say ζ(s) may only be the sum of n^(-s) over all positive integers n. When I'm doing some other problem unrelated to the Riemann Zeta function, I could define a function, say, s^4sin(3s)-cos^5(s^2)+6/s-9/s^7, and call that ζ(s). That's just as valid as calling my function f(s) or g(s).

  • @anindyabiswas1551
    @anindyabiswas1551 Před 5 lety +1

    I've waited a long time for this video. Thank you very much.

  • @SebastienPatriote
    @SebastienPatriote Před 5 lety +10

    This just went next level!!

  • @nicolasgoubin
    @nicolasgoubin Před 5 lety

    Whaaaaaaah so HANDSOME ! Merry Christmas & Happy New Year YAAAAAAAY

  • @beatoriche7301
    @beatoriche7301 Před 5 lety +17

    Great video! If I may ask, how do you actually derive this formula?

  • @NoNTr1v1aL
    @NoNTr1v1aL Před 5 lety +2

    Thank you Ramanujan, very cool!

  • @kostagerosky534
    @kostagerosky534 Před 5 lety +1

    This video was so enjoyable, you explain things so nice!

  • @fmakofmako
    @fmakofmako Před 5 lety +4

    Would it be possible for you to do a video on analytic continuation or smoothed sums? Both have relevance to this video and the riemann zeta function.

  • @mitchelvalentino1569
    @mitchelvalentino1569 Před 5 lety +4

    Yes!!! I’ve been waiting for this exact content. Very well explained. Thank you!!

  • @egalvaoepg
    @egalvaoepg Před 5 lety

    Excelent video, as always. Congrats!

  • @basedoppenheimer1497
    @basedoppenheimer1497 Před rokem

    Bro I don't even know what to say. This is mind blowing in such ways you feel like you got transported to another dimension.

  • @martind2520
    @martind2520 Před 5 lety +83

    This is awesome.
    Can you do a video proving that Ramanujan Summation is consistent with regular summation for non-divergent series?

  • @archithtelukunta4599
    @archithtelukunta4599 Před 5 lety

    Just few days ago I was just thinking whether u would ever upload a video on this series and here it is😃

  • @jzanimates2352
    @jzanimates2352 Před 5 lety +27

    You should make a collab video with 3blue1brown or numberphile!

  • @SartajKhan-jg3nz
    @SartajKhan-jg3nz Před 5 lety +1

    Everything in the video is🔥🔥🔥. The integral, the result and yes...you!

  • @ianprado1488
    @ianprado1488 Před 5 lety +7

    How many markers do you buy a month?

  • @ToHoUSA1
    @ToHoUSA1 Před 5 lety +3

    ive been waiting for this

  • @matthiashannesson7239
    @matthiashannesson7239 Před 5 lety +26

    -1/12th?

  • @angelmendez-rivera351
    @angelmendez-rivera351 Před 5 lety +12

    UPDATE: I found that if one takes the polynomial in n of degree s + 1 that gives you the sum 1^s + 2^s + ••• + n^s, then if we integrate the same polynomial in x with respect to x from -1 to 0, one obtains the same value one would obtain if one applied Ramanujan summation instead. The key is in using Faulhaber’s formula, finding the antiderivative of it in x, where n =
    x, then set x = -1, and the resulting formula is equal to -B(s + 1)/(s + 1), where B(s) is the s-th Bernoulli number. This gives the same result as Ramanujan summation, which also gives the analytic continuation of ζ(s). I’m mentioning it because I thought it was interesting.
    So this generalizes the result from my first comment.

  • @scarbotheblacksheep9520
    @scarbotheblacksheep9520 Před 5 lety +3

    If "diverges" and -1/12 are correct depending on how you think of it, could the domains of these be different? Like, is the Ramanujan summation including transfinite numbers in its sum, or something like that?

  • @mulongoduncan9308
    @mulongoduncan9308 Před 2 lety +1

    Thank you. Your derivation makes much sense.

  • @lautamn9096
    @lautamn9096 Před 5 lety +5

    Happy new year bprp!

  • @yoavcarmel1245
    @yoavcarmel1245 Před 5 lety

    very nice suit, and great video as usual!

  • @debabrataadhikari4879
    @debabrataadhikari4879 Před 5 lety

    Out of all yt channel this is the best explanation

  • @adamhrankowski1298
    @adamhrankowski1298 Před 5 lety

    Thumbed up without even watching. Loved Mathologer's vid. Have this stuff on a T-shirt. Really looking forward to what BPRP has to offer. #Yay

  • @JoshuaHillerup
    @JoshuaHillerup Před 5 lety +1

    Is there a different term for when the limit goes off to say positive infinity, versus when the limit has multiple finite values?

  • @AbbeyRoad69147
    @AbbeyRoad69147 Před 5 lety +1

    Please can you do a video on the R. summation. Thanks, I'd like to see how it is derived.

  • @dppid083wk7
    @dppid083wk7 Před 5 lety +1

    Love ramanujans work

  • @matteoserafini7704
    @matteoserafini7704 Před 2 lety

    For 1/X you just notice that the function in odd, so in a "simnetrical" interval the area in the positive part of the interval is the same of the area in the negative part of the interval, but with the opposite sign. So the sum of the two is zero

  • @user-zz3gt9wo4t
    @user-zz3gt9wo4t Před 5 lety

    Very nice video, thank you for that, but can you please make video about this integral summation what does it mean and why?

  • @angelmendez-rivera351
    @angelmendez-rivera351 Před 5 lety

    Another way in which these results make sense is in wheel theory. The field of complex number can be extended by first equipping it with an involution operator / that satisfies certain properties. Then we introduce to new elements to the complex number, /0, and 0/0. Every element of this new set has a well-defined involution: for all z, /z is well defined. Whenever z^(-1), which is the reciprocal of z, or multiplicative inverse of z, exists, z^(-1) = /z, but even for z with no multiplicative inverse, /z is well-defined. Namely, /0 = ψ and 0/0 = θ, with the properties that /ψ = 0 and /θ = θ. Also, ψ + ψ = ψ - ψ = θ, ψ + a = ψ for any complex number a, 0ψ = θ, and aψ = ψ for any complex nonzero a. Furthermore, θ + z = yθ = θ for all wheel numbers z & y (by wheel numbers, I mean complex numbers plus the two new elements we added to the field, which is now a wheel). There are some identities I have not given concerning / for all these, though right now I cannot remember them all. But there is a Wikipedia article you can find if you simply search Wheel algebra on google.
    We can give this wheel the wheel topology. With this wheel topology, 0 and ψ are boundaries of this space. As such, ψ somewhat plays the role of infinity in this space, with a few key differences, since now this is the only infinity regardless of the direction.

  • @victoryforvictims3522
    @victoryforvictims3522 Před 2 lety

    Excellent explanation. It all makes sense now.

  • @ahmedbashandy4784
    @ahmedbashandy4784 Před 5 lety

    Is there any application of ramanujan sum? Some thing like using complex number in schrodinger equation.

  • @djsmeguk
    @djsmeguk Před 5 lety +64

    What would be interesting is how the ramanujan summation formula is derived.. does it concur with convergent series as well?

    • @angelmendez-rivera351
      @angelmendez-rivera351 Před 5 lety +4

      djsmeguk I believe the answer is yes, but I’m not 100% certain.

    • @nathanisbored
      @nathanisbored Před 5 lety

      i dont think its derived, its just a definition

    • @angelmendez-rivera351
      @angelmendez-rivera351 Před 5 lety +5

      nathanisbored It is inspired by some derivation. The definition only plays in a role in the domain of functions to which it applies. It is a function of functions.

    • @angelmendez-rivera351
      @angelmendez-rivera351 Před 5 lety +5

      Markus Steiner “I think it's neither derived nor it's just arbitrary.”
      Be more specific with what is it that you mean when using the word “derived”. This may not have a derivation from the axioms, but it has a rigorous foundation on time-scale calculus, which is a theory of which the calculus of sequences is a special case. It also has equally rigorous foundation in complex functional analysis and set theory. It uses the projective extension of the complex plane, known as the topological Riemann sphere. Also, it is not arbitrary, because it can be shown that, given any argument from heuristics, the continuation entailed by the heuristics is formalized with this method presented in the video. If any continuation to summation should exist so that divergent series could be evaluated, then this must be the one. Namely, had the method of convergence of the sequence of partial sum never existed, the field axioms of addition would heuristically entail these results.
      “The thing is that it also has to work for not divergent series.”
      It does. In his following video, which sums all the square numbers of the natural numbers, I wrote in the comments section that it is easy to prove that this series sums every convergent geometric series to its correct value, and it appears as though it does so with series involving trigonometric functions as well, as well as for the sum of all 1/n^2 for n in N.
      “So there might be more possible formulas which achieve this with different results for divergent series.”
      There are. Borel summation exists, as well as Abel summation and stronger linear methods. Wheel algebra and transfinite set theory can also derive these results independently.
      “Choosing one of these possibilities is in fact arbitrary.”
      No, it is not. If two different theories derive the same conclusions, then this entails the theories are, at the very least, consistent, but it could be the case that one is a sub-theory of the other, or even more radically, that given some super-theory containing both theories, that they are equivalent theories. Being able to prove the law of cosines using either Classical Greek geometry, or else using a Hamiltonian algebra of 4-ions does not mean that choosing either theory as the foundation for a method to obtain results is arbitrary. That is not how math works, obviously, nor has it ever been this way.

    • @sl.murarikumar9675
      @sl.murarikumar9675 Před 5 lety

      czcams.com/video/odn6weKzk1Y/video.html
      Ohhhhhhh Nooooooo
      Ramanujan questions answer is right or wrong
      Very confusing
      -1/12. OR. -1/8 🤔🤔🤔

  • @sohamkumar2346
    @sohamkumar2346 Před 2 měsíci +1

    Love from India 🫡 Proud of Ramanujan

  • @federicopagano6590
    @federicopagano6590 Před 5 lety +44

    we have 2 options depending on which class we are in. But wich one is the correct answer if u are alone no classroom and u have to answer

    • @blackpenredpen
      @blackpenredpen  Před 5 lety +36

      That will be depending if I want to make my life easy or not.

    • @federicopagano6590
      @federicopagano6590 Před 5 lety +3

      blackpenredpen OK got the point diverges lol

    • @angelmendez-rivera351
      @angelmendez-rivera351 Před 5 lety +2

      Federico Espil He did not say that. Obviously you want him to say that, though, because you already are prejudiced and already believed beforehand the sum diverges. I wrote a comment addressing this.

    • @shoobadoo123
      @shoobadoo123 Před 4 lety +2

      When applied in the real world, -1/12 is the answer. This appears in physics, string theory specifically. You can google to learn more there’s a lot of info!

  • @maccook9951
    @maccook9951 Před 5 lety +2

    At about 3 minutes in I had to actually check this wasn't uploaded April 1st

  • @TheNachoesuncapo
    @TheNachoesuncapo Před 5 lety +1

    looking good steve!

  • @stratonikisporcia8630
    @stratonikisporcia8630 Před 9 měsíci +1

    Does it have anything to do with the p-adics such as the 10-adic form of -1/12 = ...3,333.25

  • @anweshaguha7366
    @anweshaguha7366 Před 5 lety +2

    Okay, so I'm in love with that "Hmm" before you start solving a tough integral, I mean tough for me😊

  • @jjeherrera
    @jjeherrera Před 5 lety +9

    Nice as always. Still, it would be interesting to understand what is Ramanujan doing that helps him to make the analytic continuation.

    • @science-y9209
      @science-y9209 Před 3 lety +1

      Ramanujan is dead but he was a genius..

  • @harshitkumar4760
    @harshitkumar4760 Před 5 lety +2

    It means that negative numbers are greater than positive and smaller too, it means its a cycle which repeats positive after negative and again positive. Think it this way as we increase the angle in tangent function its value reaches to infinity and then negative! And then again positive.

  • @infernocaptures8739
    @infernocaptures8739 Před 5 lety

    Is it possible to assign a value to Σ(n^n) with this method?

  • @stanislasnicolau2412
    @stanislasnicolau2412 Před 5 lety +1

    Hi!
    Can you give me a link or an explanation of how we demonstrate that integral from -1 to 1 of 1/X dx can be equal to 0?
    Thx a lot

    • @keoviwath
      @keoviwath Před 3 lety

      To get that answer, I think we should use the fact that the integral from -a to a of an odd function is zero.

  • @QuippersUnited
    @QuippersUnited Před 5 lety

    Quite the dapper jacket, Mr. Pen.

  • @kamidhunkumar3021
    @kamidhunkumar3021 Před 5 lety

    Integration of 1/x from -1 to 1 seems to be elementary. The definite integration is introduced as the area under curve and it is evident that the area ' enclosed '(l mean symmetric with respect to origin) by 1/x in the 1st and 3rd quadrants cancel each other.

  • @wolframalpha8634
    @wolframalpha8634 Před 5 lety +1

    Happy new year bprp

  • @stevenjohnson9466
    @stevenjohnson9466 Před 5 lety +2

    this dude loves simple maths you can see it in his smile :)

  • @epicawesomenessnucleartrin1585

    Can you integrate floor(x) from 1 to infinity? :)

  • @tomaszzywicki8446
    @tomaszzywicki8446 Před 2 lety

    Can you use this formula for convergent series?

  • @muterchak
    @muterchak Před rokem

    The formula for the partial sum of the series 1+2+3+... of N terms is S(N)=N*(N+1)/2. If we represent it as a function of X: f(x) = x*(x+1)/2 and plot this function, then the area under the graph between the points of intersection with the X axis will be just -1/12. Why is that? :)

  • @tensoescalar1
    @tensoescalar1 Před 2 měsíci

    This is a very impressive video, thank you very much, greetings from Mexico.

  • @sanatankaushik456
    @sanatankaushik456 Před 6 měsíci +1

    This is the power of the "Man who knew Infinity"!

  • @Gideon_Judges6
    @Gideon_Judges6 Před 5 lety +1

    So could this "R equals" be replaced with a triple equals, meaning is defined to be equal?

  • @elyseepasteur6163
    @elyseepasteur6163 Před 5 lety

    Please will you tell me the meaning of the R and its role to make more clear? Or give me the link of its video please 101.

  • @benjaminparra4672
    @benjaminparra4672 Před 2 lety

    What about the sum of all the factorials of the natural numbers?, I couldn't do it because the double integral (using the pi function).

  • @youtubecommentsguy9805

    That whole video was the kind of vibe it was in high school when you cannot follow a single step what the math teacher is teaching you understand nothing but don‘t dare to ask because you feel like he does a good job and is a genuine friendly guy so you don‘t want to interrupt him.

  • @alainrogez8485
    @alainrogez8485 Před 5 lety

    One word : brilliant!

  • @Ben-wv7ht
    @Ben-wv7ht Před 5 lety

    if we take f(x) = 1/x^2 we get f(0)/2+zeta(2)=0 , but as f(0)/2 approaches +oo , would we be able to say zeta(2)= -oo ? ofc I know it's false x) just curious

  • @holyshit922
    @holyshit922 Před 2 lety

    Integral Int(u/(exp(u)-1),u=0..infinity)
    can be converted to Basel problem ?

  • @shavishvilitornike
    @shavishvilitornike Před 5 lety

    I have a question: why did you select formula f(x)=x ? Why did not you select some other firmula, which would have different value at 0?

  • @Sush
    @Sush Před 5 lety

    Oooh looking fancy today!!

  • @tylertorsiello8450
    @tylertorsiello8450 Před 3 lety

    this guy is my spirit animal

  • @MrBoubource
    @MrBoubource Před 5 lety

    What if you chose some other function, like integer part of x, or x + sin(pi x), its gonna produce a different value right ?

  • @mikejackson19828
    @mikejackson19828 Před 3 lety +1

    Can you make the sum of the natural numbers to be whatever you want it to be?

  • @late7245
    @late7245 Před 5 lety +80

    1-1+1-1+........=1/2 confirmed

  • @jorgecanales4864
    @jorgecanales4864 Před 4 lety +9

    Si lo tuvieras tus videos con sub titulos en español, serian aun mas geniales, eres un genio

  • @EduardoHerrera-fr6bd
    @EduardoHerrera-fr6bd Před 5 lety

    Finally! I was specting for this including if I had to go for 2 weeks :c
    7:13 Balls Integral.

  • @integrando1847
    @integrando1847 Před 3 lety +1

    very interesting that maths say the same thing in a lot of ways, this summ appears in quantum mechanics, infinite series, complex variable, etc..

  • @chandankar5032
    @chandankar5032 Před 5 lety +1

    Its a request to make video on euler mclaurin summation. No one has made it in CZcams yet. Please🙏

  • @raiedahmednishat8883
    @raiedahmednishat8883 Před 5 lety

    You even dresses up for it.
    I love you man.
    あなたおあうしている

  • @abhijeetdas6279
    @abhijeetdas6279 Před 5 lety

    Please make a video on the Navier Stokes theorem problem proposed by the Clay mathematical institute

  • @dappermink
    @dappermink Před 5 lety

    1. Does this sum definitions gives the same result as the usual sum for any classical convergent series?
    2. Where does it come from?

    • @nandakumartulip5279
      @nandakumartulip5279 Před 4 lety +1

      1.yes or so I heard 2.given by ramanujan

    • @dappermink
      @dappermink Před 4 lety

      @@nandakumartulip5279 I don't remember the video now actually but thanks!

  • @sugarfrosted2005
    @sugarfrosted2005 Před 5 lety +3

    Fun with analytic continuation!

  • @rajatkhandelwal7276
    @rajatkhandelwal7276 Před 5 lety

    This video is so so so so so so so so much interesting plz make more videos like this

  • @binitkumarsingh8296
    @binitkumarsingh8296 Před 5 lety

    Finally i got the perfect method for that.thnx to u

  • @ytrichardsenior
    @ytrichardsenior Před 3 lety

    The numberphile video explains that this answer '-1/12' is used in some fairly complex string theory mathematics.
    This is what fascinates me. We all know that negative, and imaginary numbers are not 'real'. We can use negative numbers in order to avoid having to 'scale' our calculations. We can use imaginary numbers in order to solve problems that result in 'real' numbers.
    Is there any way that we can use these 'golden parts' of divergent series as part of a larger calculation in order to somehow get back into reality, in the same way that we can with complex numbers etc.?

  • @olegt962
    @olegt962 Před 5 lety

    In fact we can say that if a serie converges conditionally or diverges, by Riemann's theorem there exists an arrangement of serie such that converges for any k real we want.

  • @SupratheekSreedharaNagaVenkata

    @blackpenredpen 10:54 u can just say integral 1/x from -1 to 1 is zero bcoz 1/x is odd function so areas are equal in magnitude from -1 to 0 , 0 to 1 but opposite in sign

  • @roubenkhosrovian
    @roubenkhosrovian Před 4 lety

    I'm an electrical engineer and from what I know we don't use sqrt(-1) as an actual number but we use I to model cos and sin. if want to shift a voltage pi/2 rad, we multiply it in i to model different components like a capacitor or a coil.
    Is 1+2+3+4+...=-1/12 actually correct or it's just a way to model something?

    • @divergentmaths
      @divergentmaths Před 3 lety

      -1/12 is the correct sum (regarded as "remainder modulo infinity") for the divergent series 1+2+3+4+5+6+...

  • @hamsterdam1942
    @hamsterdam1942 Před 5 lety

    Ze best video about this freaky number!

  • @khaledelhoushi8834
    @khaledelhoushi8834 Před 8 měsíci

    Very fascinating video.

  • @somnathdash4428
    @somnathdash4428 Před 5 lety +1

    You got addicted to India!!! Love from India

  • @ssaamil
    @ssaamil Před 2 lety

    -1/12 is my favourite number. I love this.

  • @akshatsharma9882
    @akshatsharma9882 Před 4 lety

    I love this guy.