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From: MIT
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  • Well that was interesting to hear that part of this course as when I took physics (I am an Engineer) at my University in Physics 2 i was very interested in these topics and was dissapointed we couldn't go into detail in them. glad they got into the details and nitty gritty. I knew most of the answers what they would say cause i have done a lot of googling on the subject matter. Even though we do not know a lot about some of this stuff. There is a lot we do know

  • In fact in physics 2 my Professor had a week we did on General Relativity and a Week on Quantum mechanics. It was Very very interesting part of the course. he even tested/gave us a test question on it. Very few people could answer those questions correctly, and in fact even I did not answer them correctly. I did end up with a B in the course because i put in a lot of work though

  • lmaooo "anyone have a question about the universe?"

    silence ensues.... hahaha

  • good questions...

    not happy with the answers..no meat

    I would ask for my money back.

    Kristin disrupting and really not adding too much.

    learn to take a clue from your team member and jump in

    wrote the questions will dig for them else where.

  • Edwin: Do you wanna talk about gravitational waves?

    Kristin: No not really

  • If it were me in that classroom, I would have spent the entire hour asking questions. This subject is just so incredible

  • damn, i cant believe nobody stood up right away, wtf man. I genuinely envy those people for sitting in that chair.

  • Something from the last lecture and this one clicked inside my head. I've always had difficulty accepting time as a dimension, because we have no freedom of movement in it. We can (theoretically) bring it to a relative halt, or accelerate it to relative infinity; But we can't go backwards.

    One speaker asked if our universe could be within a black hole. And this guy pointed out that within the event horizon, There is only one eventual direction to travel, towards the singularity.

    VV

  • VV

    So perhaps the universe IS within the event horizon of some 'extra-dimensional' singularity.

    The reason we can't go back in time, is because we are unable to reach the escape velocity of this temporal event horizon. Maybe if it were possible to 'pop out' of the universe via black holes or something, we could escape the event horizon, and time would become a dimension exactly like the other three we're familiar with. You'd be free to explore it's entire length. Both Forward and back.

  • @L00NGB00W You say we cant go back in time? Whilst this is true at present I prefer to think about it like this: why dont we let time go foward before we force it back? :) The idea about us being ina singularity is an interesting theory, even more interesting when you think of the universe as 95% nothing in the first place...

  • @lfttom There is one theory to travel backwards involving wormholes. Where one hole is kept stationary, and the other hole is accelerated to light speed, or lowered near the event horizon of a black hole.

    Due to relativistic time-dilation, objects entering the 'moved wormhole' would exit the stationary hole before they left. =\

    This of course relies on the idea that wormholes are possible.

  • So, where does this positive force come from?

    This force can can come from two or more things. Either it comes from space itself or it comes from matter.

    My best theory is that it comes from matter. Since there is infinite matter on all sides of any object the force comes from all sides except to a lesser degree when other objects are nearby. All objects also absorb this force. But basicly all matter repells all other matter and matter can only reach a definite density.

  • Also the speed at which it travels is infinite. Therefore indescriminate of your speed the speed at which the force travels is infinite and the speed at which it hits the object is infinite on all sides. So whatever the speed of the object is traveling there is an equal quantity of force acting on the object at all times. If the forces are equal then it can not slow down. This is where the misconception lies and this is why gravity and black holes do not exist.

    Thank you,

  • The arguement is this: An object traveling through space in one direction will experience more of this positive force from the direction it is traveling and eventually slow down.

    An object's speed will remain constant only if the forces on all side are equal at all times no matter it's velocity. This can be explained if the forces exerted on the object are equal. No matter where the object is there is an infinite amount on all sides of the object. You can not exceed infinity nor can it be less

  • With gravity theory it can be argued that both the negative and positive forces are acting on the cannon ball. This is false. Only the positive force and any positive force on the opposite side of the cannon ball is acting on the cannon ball.

    The positive forces abound in the universe are shielded by other matter. So this positive force must travel and it's speed is infinite. The arguement used to disprove this theory is:

  • Sorry to bust your bubbles. But black holes do not, i repeat, BLACK HOLES DO NOT EXIST!

    Black holes do not exist because our current understanding of gravity is wrong.

    For example: the modern models for the rotation of galaxies don't work. So therefore science had to create a variable to add to these models in order for them to work. The variable created by science with no proof that it exists is dark matter. In short gravity does not propagate from matter and in fact the opposite is true.

  • @ewack77 Continued. All forces are in the universe are positive. If it is said that gravity is a negative force then there must be an opposite, or a lesser negative force pushing the object towards another. For example when you shoot a cannon ball out of a cannon you notice the positive force pushing the cannon ball out, however gravity theory would say that the negative force is what's pulling the cannon ball out. If there are positive forces abound then matter must sheild this positive force.

  • why does she keep interrupting the wise old man?

  • Very informative. Although the professors have rehashed the speculative theoretical research Kristin Burgess is fine.

  • This is a good lecture for the likes of myself who has never attended any lectures/classes of this kind, the students are asking the questions in a manner that i can understand and the answers are well explained, and also easy to understand, well, some of them.lol

    Overall very good, thanks for posting..

  • Is it just me, or is she being really rude by interrupting all the time..?

  • @adri041195 Stick with it! You're better off than me, three years INTO college and just wanting to do astrophysics.

  • Do black holes exist in superposition with each other?

  • @sti11h2o Do you mean that for every black hole their singularities are entangled? If that were so I think the masses for each hole would be identical, but that does not seem to be true. That's just my answer though, I don't have a Ph.D. in Astrophysics or anything :P

  • THANK YOU M.I.T.... real legends!

  • Her answering using the Ant on a ballon is bazzar and I wouldnt have let her get away with giving that answer. I have the same question, what is space expanding in, of course the any cant see the ballon expanding but the fact remains that the ballon is expanding in something like a roon. the ballon is expaning in a room therefore the ballon is to space as the room is to..? Just say you dont know and move on because no one knows. Just because you dont know something does exist doesnt mean it dont

  • @NshamirPhilly, I try to convince myself that both space and time are just the projections we can experience of a single actual thing: spacetime. The geometry of it is very different from what we infer from the projections we see. The question then doesn't make sense, like asking what's due north of the north pole. To even ask only means you're not talking about spacetime but the projections of it which are not real, even though we experience them as if they were. Color isn't real either.

  • he keeps saying area, as if the BH is 2 dimensional. He really should say volume within the event horizon.

  • I am curious about how the universe is not only expanding but it is doing so at an increasing rate this seems to defy the laws of enthrophy and doesn't this seem like a black hole in reverse

  • Start watching this video at 22 minutes into it. In the first part they are just writing questions on the board, and they do not start answering them until the 22 minute mark.

  • Thanks!

  • Also for the universe to start from a singularity there must be a center a point so just prove where that is. Also there would have to be a way to even prove that. In addition would have to prove what we call what is on the other side of the singularity call that space then that would just be that space has always been there really this would be where matter is created. Now if singularities start in many places in space time then that would mean that the universe has always been here.

  • If the Universe started as a singularity, every point in the present universe would have at one point existed within that single point. They're all in the center.

  • Sounds to me that as a black hole gets smaller it gets hotter so hot does it create new elements and a sun? So when a sun burns out would it create a black hole? So then pushing the planets away from the sun exploding then sending that to a black hole and through space would that make this a universe always here and not from a singularity. Could be a singularity in different points in the universe at different times not in one place? So a singularity at different points at different times?

  • if the sun collapsed and became a black hole we would not be sucked into it because the gravity and distance would remain the same.

  • but if you look at Einsteins plane model, when the sun becomes a black hole it stretches the plane downward which causes the the planets to go downward with it, thus sucking our planet into the black hole. Gravity changes because of the mass change of the sun.

  • @Nshamir

    You are wrong on two accounts.

    1. The sun would have the same mass therefore its gravitational attraction would be the same

    2. Einstein believed that black holes were a mathematical oddity; that is to say, he did not take the notion seriously

  • The lady lacks indepth knowledge and confidence.

  • She's young, give her time :P

  • Yes :-)

  • @sreekHi shes still only a graduate student in front of class in a subject that even experts are dodgy on,i dont think it can be expected that she has a fully indepth knowledge in a subject shes probably not confident teaching...

  • @Wicked33 Her simple method of explaining the subject matter may be beneficial to students who would otherwise be confused. However, I find it very annoying that she interrupts prof. Taylor multiple times.

    On topic, responding to the video, it is not sufficient to say that inflation was 'just there' and it was like this and that. Much too similar to religious doctrines.

  • Here are my questions.

    1.How big can a black hole become?

    2.Could a black hole become infinitely big?

    3.If the big crunch theory is true and the universe were to collapse back onto itself. What would happen to a super massive black hole during the big crunch period?

  • for 1. Black holes form when a star i beleive is 14 times more massive of the sun dies, as it begins to implode and the matter begins to accelerate inwards. it becomes so dense that normal elctromagnetic and intermolecular forces can no longer slow the collapse and the region falls into a singularity. for question 3. the black holes would simply merge with the rest of the matter and other object, such as other black holes

  • At 1:21 the students are asked to present their questions and no one has any questions to ask. I mean they are just sitting there like they don't even care and I will tell you why. The students don't give a crap. Why don't they give a crap? Because they are proabably taking about 5 other hard classes and they are tired. At my college I took chemistry and I didn't ask any questions either and you know why. Because I was tired because I had to study really hard for my other classes.

  • Yes I do know that they did ask lots of questions later but why didn't anyone jump right to it. This is MIT after all, they should have been yelling them out.

  • Kristin Burgess is hot! Please Kristin "gets on knees" marry me!

  • Could a tachyon escape from a black hole

  • good question! Because tachyons travel faster then the speed of light.

  • matter escaping from black holes is independent of their velocity. nothing can escape a black hole because it is infinitely dense. light can't escape due to this fact and not because of its speed and hence, tachyons wont escape as well.

  • I got this answer from some expert on a science forum...

    "Yes. All time-like curves (world lines of particles with mass >0) inside the event horizon end up at the singularity within a finite proper time, but tachyons (by definition) move on space-like geodesics, so that statement doesn't apply to them"

  • i wanna see some equations and deriving, not this question and answer shit. if this is what they teach at MIT, "the supposedly best technical institute in the world," just questiosn and answers, fuck them

  • best technological...not technical lol big difference..

    and as for the equations....they're there...this is one of maybe 20plus lectures..most of them arent on youtube...prof edmund wasnt there that day so it was pretty impromptu for both of them...lol this is only lecture two for pete's sake lol

  • You've missed that this video is not a part of the lectures. This is a seminar, which is held to give students the possibility of doing just this: asking and being answered.

  • Kristin, I find you highly intelligent & very attractive.

    Is it possible that black holes are distorting spacetime enough to spill matter into other dimentions?

    Is it possible that the matter that enters a black hole is channeled to the universe's "gravitational core".

    I am a firm believer that the universe is a spherical network.

  • thank for this video

  • Dear Edwin and Kristin:

    Very interesting course. Thank you. Victor

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