Hirosi Ooguri - What is gravity?

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  • čas přidán 24. 07. 2016
  • Talk at String-Math 2016 held at Collège de France, Jun27-Jul2, 2016.
    Event website: indico.cern.ch/event/375104
    Enjoy!
  • Věda a technologie

Komentáře • 20

  • @abunickabhi
    @abunickabhi Před 6 lety

    Yay

  • @Hikimaworkshop
    @Hikimaworkshop Před 3 lety

    Cause of gravity: Expansion of space is continuous from the inside of matter to outer space. However, the expansion velocity changes inside the material. This velocity change is observed by us as gravity due to the acceleration of the space. Gravity is not a property peculiar to matter, but a force of space that results from the interaction between matter and space in the expansion space.

    • @DegreesOfThree
      @DegreesOfThree Před 2 lety

      Space has no physical properties. It can't exert a force on anything, because only objects can exert a force in physics.

  • @Fransamsterdam
    @Fransamsterdam Před 7 lety +1

    In my opinion if you claim that the magnetic force of a small magnet is greater than the gravitational force of the earth, you should keep the magnet at the same distance from the object you want to attract, as the center of the earth is, so at a distance of about 6000 km.

    • @davekatz3003
      @davekatz3003 Před 5 lety

      It's not just the centre of the earth that has an attractive force but the entire mass of the earth. Thinking of that force as emanating from the centre of the earth is just a useful shorthand convention.

    • @agffga8757
      @agffga8757 Před 5 lety

      @@davekatz3003 It's not a convention at all. It is a theorem. If you are out of the sphere the force exerted on you is EXACTLY the force you would feel if all the mass of the sphere was concentrated in its centre.

  • @DegreesOfThree
    @DegreesOfThree Před 2 lety

    G is not a constant. There are anomalies all over the Earth. If Newton's equation had any relationship to the rotation of galaxies, dark matter would not have needed to be invented. If gravity had anything to do with the orbits of objects, we should expect to see satellites and planets clumped together throughout the universe like magnets. Even in the asteroid belt or Saturn's rings, we never see matter attracted to other matter, but we do see evidence of repulsion. Gravity, just like static cling, only appears to be relevant at very short distances.

  • @joed501
    @joed501 Před 7 lety

    Introducing: The Famous "Dr. Yes"...

  • @lucimariocustodio2259
    @lucimariocustodio2259 Před 8 lety +2

    No sound!

    • @GraduatePhysics
      @GraduatePhysics  Před 8 lety +1

      I'm pretty sure that there is sounds... Please check your audio settings.

    • @tompyszczuk6876
      @tompyszczuk6876 Před 7 lety +4

      The sound has been recorded only on one channel (look like right channel).Some people might have no sound or just sound in one side of speaker/headphones. In my case only right side of headphones has sound.

  • @CaliforniaMISC
    @CaliforniaMISC Před 8 lety

    Why gravitational force is the weakest ?! Try gravitational force near neutron star or large object in space. Gravitational force can shake spacetime itself . It is the weakest here on planet earth but not in universe.

    • @matt1901
      @matt1901 Před 7 lety +1

      A small magnet can cancel the gravitational field of the whole earth - now imagine a magnet the size of the sun and how strong it would be.
      A neutron star may be small in size but in terms of mass (and hence energy) it is enormous.

    • @CaliforniaMISC
      @CaliforniaMISC Před 7 lety

      it called magnetars type of neutron star, black hole gravitational pull is so powerful that it sucks all electromagnetic radiation (aka light, photons) and it is a size of Manhattan.

    • @tompyszczuk6876
      @tompyszczuk6876 Před 7 lety

      But gravity is not based on the size of the object, but on the mass of the object...

  • @AxelBliss
    @AxelBliss Před 7 lety

    all your videos - not only that - are recorded very silently - this is normal - all people have originally low volume videos but they lower a little bit the bass sounds and then increase the gain - Master volume= gain - We usually compress a little bit the amplitude , in order the "gain" doesn't cause digital distortion. I am patient with slow children. If you compare the volume of this Video with many other videos and make an average of the mean gain, you will understand that all you videos and not only that, are recorded at low volume, thus students who are afar from home thus haven't access to the best system or when there is background noise, cannot listen to your videos. Lazy people like you who don't respect the professors, don't want to buy a 100$ program that lowers the bass audio bands (because they take much space) and then increase the overall sound. Also increase only by 1 or 2 dB the area around 1kHz because that's what humans hear most. I understand you have some brain damage, and I will be tolerant and patient. I will explain everything you want. I know that people who arent mentally able to understand that what they do is statistically problematic if compared to the average action of a person, are also stubborn and create complex exuses because they hate calculating averages as physicists. You sound doesn't need averaging and relative comparison to reveal us it is problematic, but people with brain damage need official proof because they haven't the mental capacity to understand immediately the obvious. Physics is Important and must be loud (enough, not distorted of course). I am 100% certain you will generate an excuse, but I am very patient. I will explain you for millennia what dynamic range is, what averaging is, what physics is. A video recording protocol has some permissible dynamic range, and you don't manipulate your sound - so if we reveal the audio dynamic range of your videos, it's obvious you don't want to buy a compressor, an eq, and an average sound engineer. Some programs aren't good, they don't parallel exactly the sound with the audio, thus buy a good one. Also you have to know that some people buy and use different programs to manipulate initially the video and (a different program) for the mastering - the finalizing. Some people use one program for all. Please think. Try to use your brain. Don't destroy your videos because you hate students. Do it for yourself. Create good sounding videos for yourself, not for the evil enemies who want statistically (if compared to many other videos at the same system and videos of various genres) normal sound. I guess you mimic immediately uploading methods without mastering - a common problem with some universities. Don't do unwise things. I allow you to hate me, but Physics must be heard at statistically normal volume - and not your normal, but the averaging normal volume, because your normal matches your brain.

  • @primemagi
    @primemagi Před 6 lety

    so you like the rest of you have no idea what gravity is. the reason is simple, you have no idea of structure of matter. If you had a technology which could let you see matter then you will know all your talk was nonsense. gravity is simple. you are making it complicated, because you have no clue. GR is a concoction put together by German scientist/agent after my grandfather refused to tell him how gravity is generated.You loved German science so much that you took picture of starlight bent by matter, sun’s corona (space dust /plasma) and lied to public claiming it was by gravity. No space dust / plasma = no bending of light or lensing effect. also you do not know one way speed of light in space. our test showed C is not constant. full detail of gravity, structure of matter and their interaction are in my 1975 Bremen summerhouse notes. by official request only. Ferydoon Shirazi. MG1

    • @DegreesOfThree
      @DegreesOfThree Před 2 lety

      If gravity is simple, then please explain it.

    • @primemagi
      @primemagi Před 2 lety

      @@DegreesOfThree It is simple, but it is the most impotent information in science for space travel. I am happy to release it in an international gathering of scientist so everyone has equal chance to know it. so far three major western leaders did not have the intelligence to appreciate it and were too stupid to ask me officially. president of USA, Barack Obama, UK's prime minister Boris Johnson, and German chancellor Angela Merkel. If French president organised such a gathering. I am happy to present the information. United Nation was not interested at all. Nobel is run by scientist who are ignorant of fact to recognize the correct understanding. they fallow current dogmas of so called science. currently over 90% of it is wrong.

  • @gumptasirhan7042
    @gumptasirhan7042 Před 8 lety

    Why is he speaking Orcish? Thumbs down.