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.

100 thoughts on “String Theory Explained – What is The True Nature of Reality?”

  1. 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.

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

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

  4. 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

  5. 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

  6. 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!!

  7. 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.

  8. String theory is not a theory. It's not even a hypothesis, because it's not falsifiable. It cannot be proved or disproved, because it's low energy limit is quantum field theory. The mathematics in string theory is also horrendous. Its best bet was the AdS/CFT correspondence, but they can only arrive at results we already know. 99% of physicists see stringy stuff as a joke.

    Also, the Heisenberg's uncertainty principle is not fundamental in quantum mechanics. It's valid for all waves, and in QM we can derive it from the non-commutativity of observables in the Heisenberg's picture or from the Pontryagin duality between position and momentum in Schrödinger's picture. The uncertainty principle can also be violated.

    This video is quite misleading.

  9. Actually, I was thinking about the elemental particles that we're not supposed to see.
    I'm not a scinentist or anything, but I wonder what would hapen if we could force these particles to generate their own light, like, by heating them or something

  10. As may be established empirically, matter is not essential so that existence may be made subject to it, and be dependent on it. Rather, matter subsists through a meaning, and that meaning is life, it is spirit.
    Also, as may be established through observation, matter is not the thing served so that everything may be ascribed to it. It is rather the servant; it renders service to the process of the perfection of a truth. And that truth is life. And the fundament of that truth is spirit.
    Also, as is self-evident, matter is not dominant so that recourse may be made to it or perfections sought from it. Rather, it is dominated; it looks to the decree of some fundament, it is in motion in the way that that decree dictates. And that fundament is life, it is spirit, it is consciousness.
    Also, as is necessary, matter is not the kernel, it is not the fundament, it is not a settled abode so that events and perfections may be affixed to it or constructed on it. Rather, it is a shell prepared to be split, rent, dissolved; it is a husk, it is froth, it is a form.
    Consider the following: a creature so minute it can only be seen with a microscope has such acute senses it can hear its friend's voice, and see its sustenance; it has extremely sensitive and sharp senses. This demonstrates that the effects of life increase and the light of the spirit intensifies in proportion to the reducing and refining of matter. It is as though the more matter is refined and the more we become distanced from our material existences, the closer we draw to the world of the spirit, the world of life, and the world of consciousness; and the more intensely the heat of the spirit and the light of life are manifested.
    Is it therefore at all possible that there should be this many distillations of life, consciousness, and spirit within this veil of materiality, and that the inner world which is beyond this veil should not be full of conscious beings and beings with spirits? Is it at all possible that the sources of these numberless distillations, flashes, and fruits of meaning, spirit, life and the truth apparent in this material existence in the Manifest World should be ascribed only to matter and the motion of matter, and be explained by it? God forbid! Absolutely not! These innumerable distillations and flashes demonstrate that this material and manifest world is but a lace veil strewn over the inner and spirit worlds.
    Risale-i Nur Collection Words – 526

  11. Fifth Principle:
    You will understand, too, that all of these transient objects have not been created for the sake of annihilation, in order to appear briefly and then vanish. The purpose for their creation is rather briefly to be assembled in existence and acquire the desired form, so that these may be noted, their images preserved, their meanings known, and their results recorded. This is so that, for example, everlasting spectacles might be wrought for the people of eternity, and that they might serve other purposes in the realm of eternity. You will understand that things have been created for eternity, not for annihilation; and as for apparent annihilation, it has the sense of a completion of duty and a release from service, for every transient thing advances to annihilation with one aspect, but remains eternally with numerous other aspects.
    Look, for example, at the flower, a word of God's power; for a short time it smiles and looks at us, and then hides behind the veil of annihilation. It departs just like a word leaving your mouth. But it does so entrusting thousands of its fellows to men's ears. It leaves behind meanings in men's minds as numerous as those minds. The flower, too, expressing its meaning and thus fulfilling its function, goes and departs. But it goes leaving its apparent form in the memory of everything that sees it, its inner essence in every seed. It is as if each memory and seed were a camera to record the adornment of the flower, or a means for its perpetuation. If such be the case with an object at the simplest level of life, it can be readily understood how closely tied to eternity is man, the highest form of life and the possessor of an eternal soul. Again, from the fact that the laws each resembling a spirit according to which large flowering and fruit bearing plants are formed and the representations of their forms are preserved and perpetuated in most regular fashion in tiny seeds throughout tempestuous changes – from this fact it can be easily understood how closely tied and related to eternity is the spirit of man, which possesses an extremely exalted and comprehensive nature, and which although clothed in a body, is a conscious and luminous law issuing from the divine command.
    Sixth Principle:
    You will also understand that man has not been left to graze at will, with a halter loosely tied around his neck; on the contrary, the forms of all his deeds are recorded and registered, and the results of all his acts are preserved for the day when he shall be called to account.
    Risale-i Nur Collection Words 86 – Bediüzzaman Said Nursi

  12. If we have to interact with an object to "see" it, what are we interacting with in the minds eye when we visualize and dream?

  13. what if the universe or gravity is a ginormous ball
    and with more gravity an object has the more the
    ball pokes in on itself

  14. I really enjoyed this Episode! The best "easy" explanation video of String Theory I've ever seen! And in combination with the beautiful animations, it really comes to life and creates an engaging video!

  15. SEARCH THIS IN KINDLE STORE
    " The theory of relativity for dummies "
    Its a fun and simple book which anyone can understand..

  16. I have a doubt, what about using very low energy light rays?

    They should be nearly straight, better chances of hitting particles than a curve like ray.

  17. Im the president of my 10th vrade and this video inspired me to think about ways I could influence my school to get a quantum physics class

  18. I wrote something interesting and I would like to have ur opinions on my book on relativity..
    Respected sir/madam I would like to have the opinion of people of different field on my book on relativity because my book aims exactly at people away from physics . I tried to explain it in most basic level and in an interesting way. I would like to have your opinion on my book ..
    Just type Jarimin Daimary on kindle store or Amazon and it should appear.

  19. Confused – it looked like A Link to the Past but was being played on a NES so must have just been The Legend of Zelda :/
    Science is hard…

  20. Please, make the video about new, modern theory of everything "An Exceptionally Simple Theory of Everything"
    Some materials is on channel "Quantum gravity research"

  21. New agers be like
    "M-muh subjectivity means objective reality is whatever I want now watch me bless these crystals"
    Seriously though they'll start ditching string and other quantum theories once those theories start disagreeing actively with whatever magic woo-woo BS they're misusing them to support. Same with all cults. 'Evidence' is the fair-weather-friend of humans with BS to proport, to be dropped the moment someone with actual qualifications in the subject comes along.

  22. GOD STOP TEACHING THE WRONG THINGS SUCH AS DESTRUCTION OF EARTH THATS WHAT DESTROYS IT. JUST TEACH US ABOUT HOW WE FIX IT SO THAT WE CAN IMPROVISE ADAPT AND OVERCOME THE OBSTACLE.
    IN THE END, WE ARE WHAT WE LEARN

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