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String Theory Explained – What is The True Nature of Reality?

String Theory Explained – What is The True Nature of Reality?


What is the true nature of the universe? To answer this question, humans come up with stories to describe the world. We test our stories and learn what to keep and what to throw away. But the more we learn, the more complicated and weird our stories become. Some of them so much so, that it’s really hard to know what they’re actually about. Like string theory. A famous, controversial and often misunderstood story, about the nature of everything. Why did we come up with it and is it correct? Or just an idea we should chuck out? To understand the true nature of reality, we looked at things up close and were amazed. Wonderous landscapes in the dust, zoos of bizarre creatures, complex protein robots. All of them made from structures of molecules made up of countless even smaller things: Atoms. We thought they were the final layer of reality, until we smashed them together really hard and discovered things that can’t be divided anymore: Elementary particles. But now, we had a problem: They are so small that we could no longer look at them. Think about it: what is seeing? To see something, we need light, an electromagnetic wave. This wave hits the surface of the thing and gets reflected back from it into your eye. The wave carries information from the object that your brain uses to create an image. So you can’t see something without somehow interacting with it. Seeing is touching, an active process, not a passive one. This is not a problem with most things. But particles are But particles are very, But particles are very, very, But particles are very, very, very small. So small that the electromagnetic waves we used to see are too big to touch them. Visible light just passes over them. We can try to solve this by creating electromagnetic waves with more and much smaller wavelengths. But more wavelengths, means more energy. So, when we touch a particle with a wave that has a lot of energy it alters it. By looking at a particle, we change it. So, we can’t measure elementary particles precisely. This fact is so important that it has a name: The Heisenberg uncertainty principle. The basis of all quantum physics. So, what does a particle look like then? What is its nature? We don’t know. If we look really hard, we can see a blurry sphere of influence, but not the particles themselves. We just know they exist. But if that’s the case, how can we do any science with them? We did what humans do and invented a new story: A mathematical fiction. The story of the point particle. We decided that we would pretend that a particle is a point in space. Any electron is a point with a certain electric charge and a certain mass. All indistinguishable from each other. This way physicists could define them and calculate all of their interactions. This is called Quantum Field Theory, and solved a lot of problems. All of the standard model of particle physics is built on it and it predicts lots of things very well. Some quantum properties of the electron for example have been tested and are accurate up to 0, 0,00 0,0000 0,000000 0,00000000 0,0000000000 0,000000000000 0,0000000000002 %. So, while particles are not really points, by treating them as if they were, we get a pretty good picture of the universe. Not only did this idea advance science, it also led to a lot of real-world technology we use everyday. But there’s a huge problem: Gravity. In quantum mechanics, all physical forces are carried by certain particles. But according to Einstein’s general relativity, gravity is not a force like the others in the universe. If the universe is a play, particles are the actors, but gravity is the stage. To put it simply, gravity is a theory of geometry. The geometry of space-time itself. Of distances, which we need to describe with absolute precision. But since there is no way to precisely measure things in the quantum world, our story of gravity doesn’t work with our story of quantum physics. When physicists tried to add gravity to the story by inventing a new particle, their mathematics broke down and this is a big problem. If we could marry gravity to quantum physics and the standard model, we would have the theory of everything. So, very smart people came up with a new story. They asked: What is more complex than a point? A line- A line or a string. String theory was born. What makes string theory so elegant, is that it describes many different elementary particles as different modes of vibration of the string. Just like a violin string vibrating differently can give you a lot of different notes, a string can give you different particles Most importantly, this includes gravity. String theory promised to unify all fundamental forces of the universe. This caused enormous excitement and hype. String theory quickly graduated to a possible theory of everything Unfortunately, string theory comes with a lot of strings attached. Much of the maths involving a consistent string theory does not work in our universe with its three spatial and one temporal dimensions. String theory requires ten dimensions to work out. So, string theorists did calculations in model universes. And then try to get rid of the six additional dimensions and describe our own universe But so far, nobody has succeeded and no prediction of string theory has been proven in an experiment So, string theory did not reveal the nature of our universe. One could argue that in this case string theory really isn’t useful at all. Science is all about experiments and predictions. If we can’t do those, why should we bother with strings? It really is all about how we use it. Physics is based on maths. Two plus two makes four. This is true no matter how you feel about it. And the maths in string theory does work out. That’s why string theory is still useful. Imagine that you want to build a cruise ship, but you only have blueprints for a small rowing boat. There are plenty of differences: the engine, the engine, the materials, the engine, the materials, the scale. But both things are fundamentally the same: Things that float. So, by studying the rowing boat blueprints, you might still learn something about how to build a cruise ship eventually. With string theory, we can try to answer some questions about quantum gravity that have been puzzling physicists for decades. Such as how black holes work or the information paradox. String theory may point us in the right direction. When used in this spirit, string theory becomes a precious tool for theoretical physicists and help them discover new aspects of the quantum world and some beautiful mathematics. So, maybe the story of string theory is not the theory of everything. But just like the story of the point particle, it may be an extremely useful story. We don’t yet know what the true nature of reality is but we’ll keep coming up with stories to try and find out. Until one day, Until one day, hopefully Until one day, hopefully, we do know. This video was supported by the Swiss National Science Foundation and realized with the scientific advice of Alessandro Sfondrini.

Comments (100)

  1. There's brand new stuff in the Kurzgesagt Merch Shop. Check it out here: shop.kurzgesagt.org

  2. Is Dr Sheldon Cooper here? Lol 😆

  3. awesome video 😀

  4. Geometric vibration is the root of reality

  5. Takes to much brianz

  6. The theory of everything is no more than the key to Pandora's Box. And we all know where that leads, don't we?

  7. Maybe I'm just an idiot but if someone can help me out, i still don't understand what the "string" is in string theory. Is it the idea that particles are literal thin little strings instead?

  8. Yep that is a lot to talk about, I see u SHELDON

  9. 7:03 Link when did you get a duck mask?

  10. So that's why Sheldon was obsessed with string theory in the first place

  11. Leave that bird alone

  12. Never mind I m a commerce Student

  13. The universe is just one giant frog.

  14. I learn more from these videos than from school

  15. AH YES, ENSLAVED BIG BRAIN

  16. Lemme eat 2 triscuits and a bong load before we do this

  17. I like playing with String Theory.

    Signed, Schrodingers Cat

  18. Alright I was lost after minute 3… dang

  19. Do you believe in gravity?

  20. I hope Sheldon Cooper doesn't see this

  21. What if its right and theres 10 dimensions ha

  22. I watched this video because I wanted to understand "The Big Bang theory "

  23. Who came here after watching big bang theory 😂

  24. Modern mainstream physics is bollocks

  25. Don’t poke the baby chick 🐤 😥

  26. You should’ve hired Jim Parsons for the narration 😄😄

  27. Is this video Sheldon Cooper approved?

  28. The topic in this video was out of date long before you posted it. String theory has moved to M theory years ago. You can't talk about string theory without mentioning M theory.

  29. I really love your videos they are funny to watch so beautiful and brilliantly made I just love them so much ❤❤ please keep making them
    PS: I loved the Zelda Reference ❤❤❤

  30. the universe is the danger

  31. String theory is made up nonsense, just like dark matter, space time and black holes

  32. One of your best videos

  33. So weird watching "the egg", then watching this.

  34. 2:45 “We just know they exist.” without an explanation, reason, or other evidence, is religion. I’m not criticizing the theory, or saying there isn’t evidence. I’m pointing out what most people pass over as an “unimportant” detail, as a critique of a widespread, severe cultural problem simply exhibited in this moment, anything with the label “science” slapped on it is taken with zealous blind faith by masses who consider themselves wise after listening to it even though in almost everything most people call science these days there are tons of holes filled with faith via the appeal to authority tactic (shamelessly flaunted at 4:45) too many are sssooo susceptible to. Listen to everything, but question everything, and a true skeptic’s radar should go off anytime someone says “just is”, “it’s just a fact”, “it’s undebatable”, etc. Explanations are always owed in teaching. Oversimplifications are better than omissions. I’m not harshly criticizing the makers of this video. Just trying to point out this extremely common pattern to hopefully cause a few people to start thinking a bit more skeptically toward blind faith, regardless of whether it’s used by people calling it religion, politics, science, or anything else. A bunch of people believing the same thing blindly doesn’t make it more true than one person believing it. And the worshippers of anything labeled “science” always overlook the irony of things like 1:05 – 1:15 here. Even when acknowledging that past “knowledge” was false, science-worshippers fail to acknowledge that people can be wrong again. It’s always definitively said that we “can’t divide __ anymore. It’s the smallest thing in existence.” and then it gets divided, and more, and more, but each time people are just as arrogantly sure, “this is the smallest thing now. It’s a fact.” 🤦‍♂️ I know at least 99% of people on this channel will misconstrue what I’m saying and miss my points. Science is great when honest. This seems like a decent video. Just wish blind faith would stop being a constant necessity to complete every “scientific” explanation of anything on the internet and that people would stop totally accepting it with said blind faith without so much as a degree of reservation that maybe that current theories are just as capable of being wrong as all past ones. Wish people’d figure out that no, nobody knows everything and we never will. Keep trying, sure. But stay humble. Hope even 1 person sees my point. Don’t bother trying to start a fight. I’ve said what I needed to. Peace. Nice graphics & narration by the way 👍 well-presented info overall.

  35. omg,I just went off the the universe now.😅

  36. Здорово, мы это в пятом классе школы проходили.

  37. If gravity is the problem. We just unempentium (element 15)😉

  38. NOT trustable shit!!!!

  39. I think i can simplify the universe: It used to be a supercompressed thing that has such absolute density which then collapsed and explodes with a big bang which creates the ever extending universe which soon will all die out then be the supercompressed thing and it repeats

  40. Abilities in Jojo:
    Ripple
    Stands
    Spin

    Next will be STRING!

  41. Theory of Everything is, Everything about us.

    Who born will be die then reborn.

    So, we've plenty of time to figure this out. Jus' like how we reached here.

  42. Video is called "String Theory Explained."
    Doesn't actually explain the string theory.
    10/10.

  43. Wasn't string theory officially debunked not too long ago?

  44. So, Heisenberg was not just a former high school chemistry teacher but also a theoretical physicist who came up with an important theory?

  45. 🤮🤮🤮🤮🤮🤮🤮🤮🤮🤮🤮🤮🤮💩🤮🤮HBO Is gatbage shit who have spam me on mail every singel day in 2018. I JATE HBO

  46. How do you make this videos? The design is amazing

  47. Come out with an album I literally love the music in every video

  48. Damn this music be like super Mario galaxy

  49. I'm watching this at 2am while really sleepy. I think I'm gonna dream about this 😓

  50. Man does not seek to know everything; he seeks to learn anything.

  51. *Humans wants to know the reality.
    Thanos: Reality can be whatever I want.

  52. the theroy about this theory somewhat is, that it might be of any use at some point.

  53. How do we know that there are only 4 dimensions?

  54. Wait I thought Sheldon Cooper changed his study

  55. I both love and hate that half of your videos give me an existential crisis

  56. That's my old high school in the credits😂 MNG Rämibühl

  57. Intellectuals know that the earth is a

    D o d e c a h e d r o n

  58. @6:22 minus 1 thats 3 quik mafs!

  59. These guys loves birds😂🤦🏻‍♂️

  60. Your whole channel makes me feel like im on acid

  61. Maybe if as much money was spent on science than the military, and if people stopped taking useless majors instead of STEM, we could get to the answer much quicker.

  62. honestly!! this theory is just plain BULLSHIT

  63. 3:33… Good practice… Keep it up 👍 👍

  64. Very good, thank you!

  65. I have not seen any tutorial or teacher explaining Heisenberg Uncertainty principle such cleanly yet precisely…

  66. The Heisenberg Uncertainty Principle is NOT the observer effect, although it is commonly confused as such (as shown in this video, unfortunately).

  67. You have it wrong we are studying a cruise ship to make a row boat 🤦‍♂️

  68. People who watch Kurzgesagt > People who watch Rick and Morty

  69. 2 + 2 isn’t always 4..

  70. if you think about it anything is reflective

  71. When u observe something are u interacting with it tho? Wouldn’t photons just bounce of it anyways even if you weren’t observing?

  72. I wish the Kurzgesagt would make half hour episodes. I love these animations. They make me feel warm and cozy

  73. dude who loves coming to this channel late at night

  74. Complimentary ba dum tss comment….

    Now to continue watching…

  75. Wat if the universe was a nutshell

  76. Good video! But i think that heisemberg principle its another thing: ∆x • ∆p >= h / 4π

  77. 6:06 if u say that again, Sheldon's gonna whoop ur ass

  78. Ohh I bet that Sheldon (Cooper) could help you with this video.Hes a genius!!

  79. 6:28 is that math real ?
    While i was thinking about it, wouldnt it be cool if someone came up with a way something does NOT equal ? 2=3 for example

  80. i like the sound light ray does when it hits the eyeball 1:30

  81. Everytime I think I understand something… I… I don't…

  82. I just want to say that, despite the cartoonish style and the jokes, this was a surprisingly elegant presentation!

  83. maybe I don't get this right due to language, but, doesn't accurate up to 0.000000000002% actually mean not accurate at all? errors up to 0.00..2% means high accuracy

  84. me:" wakes up"
    everybody else at the reality simulation center of Nebula :" .0. "

  85. Hello Graphic Artists….Don't use too many colors….it can't let you focus on one thing you want to see in these ver fast and cartoonish presentations…Thanks!!

  86. can we get a 1 hour of 0s 3:31

  87. Pucci: Do you belive in gravity ?

  88. Actually 2+2 is not 4 if using base 3

  89. There are two heisenberg principles, one that is found in textbooks(that we can not measure because of instruments), and one that is the real one implying superposition(from the intrisic nature of reality) and has the formula.

  90. The English accent makes me believe whatever I hear!

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