tag:blogger.com,1999:blog-22973357.post7649655709119757860..comments2016-10-01T04:22:39.029-04:00Comments on Backreaction: This and ThatSabine Hossenfelderhttps://plus.google.com/111136225362929878171noreply@blogger.comBlogger14125tag:blogger.com,1999:blog-22973357.post-10189008384587386872009-04-13T18:58:00.000-04:002009-04-13T18:58:00.000-04:00I too enjoyed Valpy's article regarding Charles th...I too enjoyed Valpy's article regarding Charles the Cat. <br /><br />Here's an interview I did with the both of them...<br /><br />http://www.tvo.org/TVO/WebObjects/TVO.woa?video?AKFF_Full_0_0_CharlesTheCat<br /><br />Best,<br /><br />StevenWeekend Pictureshttp://www.tvo.org/TVO/WebObjects/TVO.woa?video%3FAKFF_Full_0_0_CharlesTheCatnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-5482005016457251702007-11-01T06:35:00.000-04:002007-11-01T06:35:00.000-04:00On the other hand, I've met a surprising number of...On the other hand, I've met a surprising number of Italians (in Italy), who don't drink coffee.amaragrapshttp://www.blogger.com/profile/15769062084934190681noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-78821339943043488962007-10-31T21:11:00.000-04:002007-10-31T21:11:00.000-04:00I wish there *were* Starbucks in Italy. Italians c...I wish there *were* Starbucks in Italy. Italians could go there to find out how unbelievably *bad* coffee is everywhere outside Italy, and feel more grateful for being Italians. On the other hand, I have actually seen Italians going to McDonald's. To get there, they had to walk past a family-run trattoria serving food better than anything you will find on the entire North American continent.beowulfnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-9944203643908235602007-10-31T21:07:00.000-04:002007-10-31T21:07:00.000-04:00Hi Stefan, I agree that it is reasonable to requir...Hi Stefan, I agree that it is reasonable to require the sphere to remain a manifold. That is natural. It is even more natural, however, to forbid self-intersections! Immersions/embeddings. The problem then, of course, is that you get a boring theorem which is easy to prove....yes, as pedagogy it is very impressive; but as mathematics......beowulfnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-26774214521674157972007-10-31T17:51:00.000-04:002007-10-31T17:51:00.000-04:00Halloween Wormholes & Nairai Universes<A HREF="http://space.newscientist.com/article/dn12853" REL="nofollow">Halloween Wormholes & Nairai Universes</A>QUASAR9http://www.blogger.com/profile/00593390598251093182noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-30730706899370212752007-10-31T17:40:00.000-04:002007-10-31T17:40:00.000-04:00Dear Bee,tthis mathematical trick is very surprisi...Dear Bee,<BR/><BR/>tthis mathematical trick is very surprising, and the movie is really impressive. And, it is more than 10 years old, which makes the tricks even more stunning...<BR/><BR/><BR/><BR/>Hi beowulf,<BR/><BR/>I agree that in the movie, the requirement that all allowed transformations have to avoid kinks appears quite ad hoc, and arbitrary. <BR/><BR/>However, there is a precise mathematical definition of this "non-kinkiness" which is very reasonable: the requirement is that the deformations are <A HREF="http://mathworld.wolfram.com/ContinuousFunction.html" REL="nofollow">continous</A>, or even <A HREF="http://mathworld.wolfram.com/SmoothStructure.html" REL="nofollow">smooth</A>, and that the shape which is transformed keeps the structure of a <A HREF="http://mathworld.wolfram.com/Manifold.html" REL="nofollow">manifold</A> all the time, which means that for each point on the shape there is a small neighbourhood which "looks like" the plane, or more generally like a neighbourhood in n-dimensional Euclidian space. <BR/><BR/>The restriction on possible transformations implied by this definition has even some physical equivalent: if you imagine the shape as, say, a freely floating soap film, bending and stretching of the film is allowed - and the film may have a chance to sustain these kinds of deformations. However, the kink will always and necessarily introduce some singular point, where the film cannot avoid rupture (or it has to be kept fixed from the outside).<BR/><BR/>Of course, there is still this tricky problem that mathematicians sometimes don't care about that real soap films always have to be embedded in three-space, and that the "pass through itself" may not work in practice ;-)<BR/><BR/><BR/>Best, Stefanstefanhttp://www.blogger.com/profile/09495628046446378453noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-71182656303714547652007-10-31T17:24:00.000-04:002007-10-31T17:24:00.000-04:00Well of course in the ukthe mug and cup handlesare...Well of course in the uk<BR/>the mug and cup handles<BR/>are on the right hand side<BR/><BR/>have you ever seen a cup for left-handed people?QUASAR9http://www.blogger.com/profile/00593390598251093182noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-13568372195715309042007-10-31T15:28:00.000-04:002007-10-31T15:28:00.000-04:00well, at least where I've been lately, let me see....well, at least where I've been lately, let me see. Germany, Austria, France... oohm, they don't have Starbucks in Italy apparently, neither in Poland, and I couldn't find one in Lisboa... okay, apologies, I admit it's not exactly a representative sample. Best - B.Beehttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-69083702965491600692007-10-31T15:24:00.000-04:002007-10-31T15:24:00.000-04:00You get spoons in EU Starbucks? - which parts of t...You get spoons in EU Starbucks? - which parts of the Erope?<BR/><BR/>And there was me, trying to eat a blueberry muffin with those chopstick thingies (wooden sticks)<BR/><BR/>PS - The straws are fine for frappacinos, but do not use with hot chocolateQUASAR9http://www.blogger.com/profile/00593390598251093182noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-52199349736598267962007-10-31T12:59:00.000-04:002007-10-31T12:59:00.000-04:00Hi Klaus,I can't stand the Starbucks sandwiches! I...Hi Klaus,<BR/><BR/>I can't stand the Starbucks sandwiches! I think tuna is the worst. No wait, actually they have one with dried tomatoes which I find even worse. But I like their carrot cake :-) What I will never understand though is why they don't have spoons in the Starbucks in North America (they do have spoons in Europe). I never know what to do with the milk foam. I've seen customers trying to use the wooden sticks, but of course it doesn't really work. Best,<BR/><BR/>B.Beehttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-61343674374117054792007-10-31T12:54:00.000-04:002007-10-31T12:54:00.000-04:00Hi Beowulf,I didn't say it's interesting... but it...Hi Beowulf,<BR/><BR/>I didn't say it's interesting... but it's well done. They had a difficult task to explain and visualize a fairly abstract issue, and I think they did an excellent job. Best,<BR/><BR/>B.Beehttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-25278087170045022152007-10-31T08:03:00.000-04:002007-10-31T08:03:00.000-04:00Beowulf,I think maybe its because if you embed a s...Beowulf,<BR/>I think maybe its because if you embed a sphere in more dimensions, the new allowable motions, when projected would look like you were passing it through itself. So if you are studying intrinsic properties of the sphere it makes sense to allow it to pass through itself (as in the Klein bottle construction) but not to make edges (which doesnt correspond to allowable motions in more dimensions).Hagnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-24304849955692057652007-10-30T21:49:00.000-04:002007-10-30T21:49:00.000-04:00Sorry, but I found the "turning the sphere inside ...Sorry, but I found the "turning the sphere inside out" thing deeply *un*interesting. You are allowed to make it *pass through itself* but you are forbidden sharp corners? Why? So that you can prove something. This is why mathematics can never be as interesting as physics.....Beowulfwww.grendelsmom.comnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-21961163329404755372007-10-30T17:43:00.000-04:002007-10-30T17:43:00.000-04:00Hi,We just had a STARBUCKS opened nearby my workpl...Hi,<BR/><BR/>We just had a STARBUCKS opened nearby my workplace out here in Korea... Cool!! but..<BR/><BR/>Big disapointment! they serve no sandwiches (tuna is my favorite) and no BLUEBERRY CHEESECAKE :-( AARRRRRGG#¤"&XXX¤#?/%&/##!<BR/><BR/>Best<BR/><BR/>KlausAnonymousnoreply@blogger.com