Spacetime Versus the Quantum | Joe Polchinski

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  • Опубликовано: 5 ноя 2024

Комментарии • 38

  • @Aluminata
    @Aluminata 9 лет назад +1

    If you shine a light beam out from a black hole it will not travel upwards and bend back down. To travel upwards would be to make progress towards a lesser gravitational force from a greater ( infinite) gravitational force. Of course its moot because there could be no you or your electric torch light in such a place.

  • @MilanKarakas
    @MilanKarakas 6 лет назад

    At 16:47, it is wrong: "Speed=1/UoEo", where it should be: "Speed=1/SQRT(UoEo)". Sorry but I can't write 'micro' and 'epsilon' with subscript of zero, so I am using Eo as a vacuum permittivity and Uo as a vacuum permeability.

  • @birricforcella5459
    @birricforcella5459 8 лет назад +3

    Maybe someone here can explain something to me that stuck in my craw ever since Hawking came up with his explanation for the temperature of black holes. This may be a dumb question, but if half of the virtual pair of particles falls into the black hole and the other half wanders off into the universe at large, wouldn't that supply the black hole with the mass/energy of that particle? To my naive mind it looks like the black hole actually gains mass while the energy that is supposedly radiated away from it comes from the outside of the hole and is ADDED to the outside universe. Remember that he virtual particle did not exist before it winked into existence, and usually virtual particle pairs annihilate to keep the bookkeeping of the universe balanced. But now we have two real particles, created ex nihilo which both add to the overall mass/energy of the universe?

    • @rimburemus7587
      @rimburemus7587 8 лет назад +2

      good question. It's because the particle that enters the black hole has negative mass. A negative mass entering the black hole means the black hole loses mass. The reason the particle's mass is negative is because it's partner is positive,meaning togother they have 0 mass,thereby not violating mass conservation.

    • @birricforcella5459
      @birricforcella5459 8 лет назад

      That doesn't work. Negative mass (whatever that is) would make the black hole lighter (albeit a tiny amount) and thusly also contribute, like the positive mass, to the overall imbalance of the universe.

    • @jeffmotsinger8203
      @jeffmotsinger8203 7 лет назад +1

      But virtual particle pairs come in all flavors equally so there is no net gain or loss even if negative mass were a possibility. If mass is interaction with a Higgs field, how does one get negative mass? Wouldn't negative mass imply anti-gravity? I'll have to look into that, its not something I'm familiar with.

    • @jeffmotsinger8203
      @jeffmotsinger8203 7 лет назад

      Well, it seems negative mass is only a conjecture....and even then not as a particle but as a region of space with negative density, something apparently not ruled out by QFD but is yet to be observed....and would violate Einstein's positive energy condition. Anyway, my argument still stands vis-à-vis just as many positive particles will be sucked in as negative ones so the net affect is zero.

    • @Reddles37
      @Reddles37 6 лет назад +1

      He means that when a particle pair is produced one of the particles has positive energy and the other has negative energy, so the total energy is conserved. The positive energy particle can escape, while the negative energy particle falls into the black hole and reduces its mass. This is allowed because the negative energy particle is still a virtual particle, which means it only exists for a short time before it annihilates with a particle inside the black hole. Because of the quantum time-energy uncertainty relation, this kind of short-lived particle can have energies and momenta that wouldn't make any sense for a normal particles.
      A similar problem arises if you just think about a simple interaction like two particles bouncing off of each other by exchanging a virtual particle. It makes intuitive sense if you think about a repulsive force, since exchanging a particle would make both original particles recoil away from each other. If you think about an attractive force though, you'll see that the virtual particle must actually have negative momentum for it to work.
      By the way, I believe some people have also derived hawking radiation by thinking about the particles inside the black hole escaping via quantum tunneling, if that explanation makes more sense to you.

  • @naimulhaq9626
    @naimulhaq9626 5 лет назад

    QM provide a window to comprehending reality, that classical interpretation fails to. The window consists of four outlets. 1) Observation changes waves into particles (the dual nature of reality). 2) Information enables to comprehend 'complexity' (Quantum Computing nature of reality). 3) Entanglement provides a window that enables us to comprehend unity of 'no boundary' universe resulting from a single probability wave function, governing everything and every process in the universe, eliminating randomness/chance (self-error correcting QC function), producing/creating life and consciousness.
    QM/string theory leads us to an intelligent conscious 'observer', collapsing the quantum field into particles, implying ID and divine purpose.

  • @tberrardy
    @tberrardy 9 лет назад

    I'm not a scientist, but this guy's description of the singularity seem to be very different than the way Kip Thorne describes the BH. I thought I understood a small bit of Thorne's description of the BH as being a total gravitationally distorted region of space time in which the mass that created the hole is transitioned the energy that causes the tremendous distortion of ST. I think Thorne said there is not a massive and dense singularity within.

  • @Nafe3alyasi
    @Nafe3alyasi 6 лет назад +2

    May your soul rest in peace

  • @dlwatib
    @dlwatib 9 лет назад +4

    Just because information is beyond a horizon doesn't necessarily mean that it is destroyed. A ship going out to sea doesn't destroy information just because it carries a log book beyond the horizon. Perhaps a black hole absorbs matter, energy, information and entropy until some upper bound, and when it reaches a critical mass/energy/information/entropy limit it explodes into some sort of supernova-type of event that creates a new star or galaxy or quasar or whatever from the black hole and starts broadcasting all that information and entropy and energy again.
    Whenever we can't understand something, there's a good chance that it's because we're being too arrogant and assume that the best place to know the truth is our own point of view. Clearly, the guy who enters the black hole isn't going to see any sudden destruction of information. Assuming his space suit allows him to survive the gravity, he'll be able to read his ipad just fine.

    • @mrjp2149
      @mrjp2149 7 лет назад

      dlwatib, or the exact opposite. Black hole evaporation, aka Hawkins Radiation.

  • @Unidentifying
    @Unidentifying 10 лет назад +1

    i still wonder what makes joe think we can divide by zero, it makes it quite .. circular D:
    thanks for this upload!!

  • @ramirocordero1776
    @ramirocordero1776 6 лет назад

    How about Berkelium DOESN'T Follow the Normal Rules of Quantum Mechanics, nobody wants to talk about this big issue for Quantum Mechanics, can you imagine if only one discover was against Relativity it would be a disaster.

  • @jiansenxmu
    @jiansenxmu 6 лет назад +1

    R.I.P.

  • @sarahlight956
    @sarahlight956 3 года назад

    Imagine the train of light, a conic train that gets bigger and bigger advancing in a regular, uniform way, growing exponentially from the source...
    Every particle in this train, electrons for exemple, do not have the classic motion you describe.They draw a spring , that gets larger and larger, with everything else, proportionally...the expansion is not felt when you are inside light, engolfed in space time, since everything is growing with the same rate...And while everything, every elementary particle does this motion, in torch to torch motion, when everything seems to move, and nothing moves in reality...in the center of each single motion, dark grows, the trail of information left behind...and as the spring gets larger, more space time is manifested...And you Sir, and all those with you in this short space time memory, stored in mysterious places of the universe, already dead, and brought to life , now , for me to see...
    You are an alien moraic from a very distant place...Can you see?

  • @Hythloday71
    @Hythloday71 10 лет назад

    Where did he pit QM against GR ?
    (in the sense that clearly one or the other, or both are wrong)

    • @shadfurman
      @shadfurman 9 лет назад +1

      ***** I thought they'd proven Hawkins radiation...?

    • @jeffmotsinger8203
      @jeffmotsinger8203 7 лет назад

      Mostly on the "information is never lost" front. They don't ever define what they mean by "information" but he represents it with a picture of a book. it seems to me that the 'heat death' theory of the universe pretty much wipes out all information.

    • @jeffmotsinger8203
      @jeffmotsinger8203 7 лет назад

      Hawking radiation would be extremely long wavelength (has to climb out of that incredible gravity well) and so probably hard to detect. Very likely there to be found but doesn't prove anything that hasn't already been thought of.

  • @Aluminata
    @Aluminata 9 лет назад

    "Very fast and very small..." probably not destined for an extended relativity with a black hole

  • @birricforcella5459
    @birricforcella5459 8 лет назад

    Sorry, comment was for a different lecture. But maybe someone can answer the question here anyway.

  • @p199a
    @p199a 9 лет назад +1

    iam nub in physics but i liked this lecture ALOT

  • @TimondeNood
    @TimondeNood 5 лет назад

    Joe seems a funny guy haha

  • @jeffmotsinger8203
    @jeffmotsinger8203 7 лет назад +2

    This must be the 7th or 8th explanation I've heard of Hawking radiation that is completely nonsensical. Saying "a particle falls into the black hole causing it to lose mass" does not make sense. He says we see mass coming away from the black hole but that mass was never in the black hole so its just another bit of nonsense.

  • @mgarlop
    @mgarlop Месяц назад

    A true genius. A sad loss.

  • @theaverageindianguy4569
    @theaverageindianguy4569 9 лет назад

    Hey Joe, you are so good. Keep making the videos like this babe. Love you. xoxoxoxo

  • @alexwilson8034
    @alexwilson8034 4 года назад

    oh my god dude open your eyes. He doesn't even blink or look at the audience

  • @calaverasgrande
    @calaverasgrande 9 лет назад +1

    I just cant listen to this guy. He goes from very quiet to very loud and stammers too much. Probably going to get into some interesting stuff, but get a better sound man, quit stammering!

    • @george5120
      @george5120 6 лет назад +3

      calaverasgrande Perhaps because he is dying from brain cancer. RIP

  • @theartificialsociety3373
    @theartificialsociety3373 9 лет назад

    Everything discussed seems interesting but so disassociated from anything that relates to what matters to our world and our survival. One must understand that these equations are correlations that approximate the behavior of the system for certain situations. The Maxwell's equation do not explain why electron orbits are stable non emitting states. The equations simply breakdown and are not applicable for that situation. Likewise, the is no surprise that certain correlating equations do not fully explain black holes. But realistically who cares. These very intelligent people are getting awards while our world is being destroyed by old technologies. Awards should be given to those discovering solutions for solar energy, wind power, water resource management, pollution and recycling. Black holes are interesting mathematical exercises but no value to our immediate critical needs.

    • @christophersewell6611
      @christophersewell6611 7 лет назад +3

      What you've said is really quite funny because all of those technologies you've mentioned have underpinnings in the work of theoretical physicists who were working at the limits of human knowledge. Einstein wasn't inventing the GPS Satellite by coming up with relativity, and Faraday wasn't building a computer. And it's not like people working in theoretical fields make significantly more than their applied counterparts or engineers do. Your argument sounds like that of a person who takes science for granted. It would be better if you informed yourself.

  • @gsanewphysics8902
    @gsanewphysics8902 6 лет назад

    GRT was invalid, in special relativity Einstein was only able to derive E = mc² for a particle completely at rest.
    Spacetime is nonsense.There are no intersection between GR and quantum mechanic. Quantum gravity is impossible.

    • @aoflex
      @aoflex  6 лет назад

      GSA New Physics Small stuff and heavy stuff = intersection

    • @rainertheraven7813
      @rainertheraven7813 6 лет назад

      QM is nonsense. Look only at Qteleportation. At entanglement moment all states are fixed. But they won´t believe it. And for GRT there are real proofs. Gravity and inertia derive from block-spacetime, yet they call for Higgs-nonsense.