Causality and Propagators in Free Klein-Gordon QFT

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  • เผยแพร่เมื่อ 20 ธ.ค. 2024

ความคิดเห็น • 29

  • @tillerbrady6624
    @tillerbrady6624 11 หลายเดือนก่อน +1

    At 10:00, the change of variables V shouldn’t have a square on it for (x-x_0)^2.

    • @NickHeumannUniversity
      @NickHeumannUniversity  11 หลายเดือนก่อน +1

      You are correct! Thank you for noticing! I'll pin this for future reference

  • @quantumworld9434
    @quantumworld9434 ปีที่แล้ว +4

    I've watched many lecture series on qft but your video lectures gave me proper understanding of qft.

  • @RobertBabani
    @RobertBabani 4 หลายเดือนก่อน +1

    The best introduction to Quantum Field theory I have ever seen, you have implemented what I have been wanting to see for 61 years, using Bob’s Baby step approach to derive the propagator for the Klein Gordon Equation, thank you so much, if you are ever in Albuquerque New Mexico, let’s meet at the Olive Garden and I’ll have my favorite, fettucine alfredo with broccoli, you totally rock, thank you, thank you

    • @NickHeumannUniversity
      @NickHeumannUniversity  4 หลายเดือนก่อน

      Thank you for the kind comment! I'm glad you enjoyed the lecture!
      Unfortunately, I'm half a world away, but I am honored by the offer!

  • @nirajangupta7406
    @nirajangupta7406 ปีที่แล้ว +4

    Finally, Nick sir remembered his channel's password😉😉. Anyway, I am so happy you uploaded a QFT video after such a long time.

  • @billdicklechips
    @billdicklechips 2 หลายเดือนก่อน

    You good sir are underappreciated. This helped immensely with my QFT homework.

  • @kevinowens1
    @kevinowens1 ปีที่แล้ว +1

    You were born to teach Physics my friend. Please keep going. You saved my neck in Electrodynamics. I wish you had taught other chapters like 3, 4 and 5. What you gave was priceless! it helped me understand it, not just work problems. Thank you

  • @erikstephens6370
    @erikstephens6370 ปีที่แล้ว +1

    50:53-51:40, Keep in mind, this transformation is only possible if x-y is a spacelike vector and not a timelike one. This makes our commutator go to zero for x, y that are too far apart to "communicate" according to special relativity. Doing the integral for the timelike case does not give zero (it doesn't converge interestingly enough).

  • @jasonpalin4521
    @jasonpalin4521 ปีที่แล้ว

    Glad to see you back - and for QFT!

  • @dondada2096
    @dondada2096 ปีที่แล้ว

    Thank you so much for uploading again!

  • @kevinowens1
    @kevinowens1 ปีที่แล้ว

    Thanks!

  • @HansTube1
    @HansTube1 ปีที่แล้ว

    Thank you Nick. Hopefully we wont wait another 8 months for the next video 😄

  • @petershotts8571
    @petershotts8571 9 หลายเดือนก่อน

    Thank you so much for all your videos. I really appreciate your clarity and detail. I am confused, however, when you consider the case of D(x-y) when x0-y0=t whilst xi-yi=0. I follow the maths when you show that as t tends to infinity x0-y0 is finite. However I do not see what the problem is. If the zero component of x is the time component why shouldn't there still be a non-zero value for x0-y0 as t tends to infinity? Given that the particle remains in the same place, why does this contradict causality? Peter

  • @zanxder7536
    @zanxder7536 ปีที่แล้ว +1

    I recently had my QFT exam's it would have been great if it was uploaded earlier.

    • @zanxder7536
      @zanxder7536 ปีที่แล้ว

      thanks for the awesome QFT content though.

    • @NickHeumannUniversity
      @NickHeumannUniversity  ปีที่แล้ว +2

      My apologies. It's been a tough year, and a lot of things hindered me from making videos. I will do my best to stay on track now!

  • @Dirac_0
    @Dirac_0 6 หลายเดือนก่อน

    how do you find the exponential decrease for time like case. When you let t goes to infinity. Is there some kind of derivation ?

    • @Dirac_0
      @Dirac_0 6 หลายเดือนก่อน +1

      i found it :)

  • @SagnikSaha-cj6nl
    @SagnikSaha-cj6nl หลายเดือนก่อน

    Thank you very helpful

  • @onnilattu9138
    @onnilattu9138 11 หลายเดือนก่อน +3

    Awesome videos but brother PLEASE go back to the dark background lmao

  • @harshit3602
    @harshit3602 ปีที่แล้ว

    Plz upload full qft

  • @luisbielmillan8467
    @luisbielmillan8467 9 หลายเดือนก่อน

    very very useful. My teacher just presents the conclusion with barely any explanation ...

  • @tillerbrady6624
    @tillerbrady6624 11 หลายเดือนก่อน

    Why do you always say “propagate in an arbitrarily short period of time”? Is there a reason you add the arbitrarily short?

    • @NickHeumannUniversity
      @NickHeumannUniversity  11 หลายเดือนก่อน +1

      It means "in any short amount of time", meaning that there is no limit, and thus, that it can surpass the speed of causality (speed of light)

  • @youtubesucks1885
    @youtubesucks1885 10 หลายเดือนก่อน

    Will you do some vidoes about Yang-Mills theory and interacting QFTs? As far as I am aware every video until now was about the trivial free case.