What are they, where do they come from, and the proof? Lisa Randall: So youre jumping to multiple dimensions, which is also something I work on. And I kind of work on it in connection with trying to answer some of those questions that we just mentioned. But the idea of multiple dimensions has been around for ages in terms of just mathematical concepts. But in terms of physics it was more recent after Einstein developed his theory of general relativity. And it was observed that his theory works for any number of dimensions. It doesnt have to be three. But people also think about extra dimensions because of string theory, which is a candidate theory for unifying quantum mechanics and gravity, which seems to require extra dimensions of space. But the other reason we think about extra dimensions is because they might actually have implications for our world and explain properties of matter that weve observed, and how they . . . why masses are what they are for example. Well theres a number of ways to think about what dimensions are. I hope we all know where three dimensions are, which you can say are left, right; forward, backward; up, down. And if you think about it, three . . . we say there are three dimensions of space. And sometimes we need three coordinates to locate some objects in space. So you can say longitude, latitude and altitude. So if there were more dimensions, you would need more coordinates. Now of course for whatever reason we are not physiologically designed to observe those dimensions, but that doesnt mean they dont exist. One way of thinking about it is . . . Maybe the best way of thinking about it is the way that someone named ____________ did it in the late 19th century in a book called . And he said suppose there were two dimensional creatures living in a two dimensional universe? They would have the same trouble conceptualizing three dimensions that we have when we try to conceptualize more than three, such as four. And so he asked questions like,"What would observers in this two dimensional universe see, say, if a three dimensional object like a sphere passed through the universe?Â And what this flatland universe would see would be a series of disks that grow in size and then decreased in size. In the same way that we can certainly think about a two dimensional world inside a three dimensional world, it could be that we observe three dimensions but really there are more. And if a hyper sphere say a four dimensional sphere passed through our universe, we would see a series of spheres that grew in size and then decreased in size. The fact that we dont observe those extra dimensions doesnt mean they dont exist. And they are hard to conceptualize. They certainly are hard to visualize. But we can think about them mathematically and conceptually without too much trouble. You want evidence, do you? Well we dont know if theres evidence yet. So one reason we think about it is to decide what would be the evidence. So how do we know if these dimensions exist? And of course you cant answer that question until youve really thought it through and thought how are they hidden; what would be the implications? And we havent seen them yet. I mean the reasons that we think about it, like I said, are string theory and the fact that they might have implications for our universe. But how can we test whether it has these implications? Well what were going to do . . . not me but ________ will do is look for evidence of particles associated with travel in the extra dimensions. That is to say if particles traveled in the extra dimensions, there would be partner particles called"Kaluza-Kline particles that are like the particles we know about. They have properties that interact similarly, but they have mass. And their mass reflects the extra dimensional geometry. Thats because they have momentum in those extra dimensions. And so what well do is look for evidence of these extra Kaluza-Kline particles. And if we see them, and if they have the properties that we predict, it would be evidence for extra dimensions. Recorded On: 11/2/07

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Oozi Leeds:Poor lady looks tired from having such a huge brain and being so smart.Venkatesh babu:All in f orbitals of electron probability of the curvature of dark energy and dark matter is the multiple universe of dimensionality. Black holes connecting them.LanDi3000:Intelligent woman.....rrrrr.....Steve Foley:inward foldingRick De La Garza:Isn't dark matter, dark energy, and antimatter evidence of the "traces" of other dimensions?Peter Van Gemert:What an impressive mindVenkatesh babu:People always ask what are multiple dimensions. Just to explain the earth has different elements and it has different compounds and the compounds make structures like the stones and water etc. Again asking for higher dimensions is like the sun and planets etc. Each has a power over the other based on how energy density is distributed. For negative energy density their is positive energy density though they can join to nothing. But asymmetry always exists and that is why we see the world right now. It could have been to nothingness. But that small part keeps on going and into the future.IntelligentDesign-Evolution-God:I like the fact that prof. Randal is honest about not knowing a lot in physics. Perhaps 4 dimensions are like stacking 3-D boxes; I think an 11-year-old explained it that way on YouTube. He probably had not been to Harvard.Kennedy Grey:what happened to the prom queen after she dropped a couple tabs of LSD and her date passes outCate Jo:Reading the comments and I´m like.. why are men writing stupid, disgusting stuff under videos of intelligent women? Women never do that to men´s. Well, then I realize again; They were right. Men ARE trash. Men ARE pigs, men ARE stupid whores.Cate Jo:Reading the comments and I´m like.. why are men writing stupid, disgusting stuff under videos of intelligent women? Women never do that to men´s. Well, then I realize again; They were right. Men ARE trash. Men ARE pigs, men ARE stupid whores.HiggsField:I'd love to sit and chat about stuff like this with her, what a great dinner date she would be.morgellon Betancor:NADA ES LO PARECE,SALUDOSRasputin 883:I want to marry your braaain... :pMike M:More than 3 dimensions is easy. Time being the fourth dimension, obviously. Beyond that is BS.Richard Lepage:Trev0r98 her mind is way superior to wards..and she pure women....get your head out of your butt hole...she is one hella smart lady.Joseph Johnson:Great job at explaining multiple dimensions. The Greeks and ancient Egyptians theorized chemistry (e.g., atoms, electrons, interactions) and proof came centuries later with electron microscopes. So proof will come or is already here and needs to be found. :) PS moderator should remove a lot of nonsense comments.Ion Murgu:SHOE Theory is Celebrating around of Life Climatic Research Center - 2 years from Sending FLT in Science Fundamental, and more then 3 years maybe from The Tear Of Geea or #Inerton - JOIN US! here is the start for a Lot Lisa, I know you are for Super Symmetry , instead I said for 3 years or more -" Symmetry is a tend when asymmetry is the engine"Earth Proud Day an American Day for 2 years but soon an International One.

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