by melroysoares@hotmail.com
 P: n/a In article <4330052f$0$27407$8fcfb975@news.wanadoo.fr>, jacob navia wrote: >There are other conceptual problems. >Rotation implies a center where the rotation is zero. This is intuitively obvious, so it should come as no surprise that it's not true. In general relativity, there are solutions to the Einstein field equation that describe a Universe that is rotating but that has no center. Specifically, there are homogeneous (but not isotropic) cosmological models in which every point can equally well be regarded as the center of rotation. Remember when you first learned about the expansion of the Universe? Back then, it probably seemed completely obvious that you couldn't have expansion without having a center away from which everything was expanding. After a while, you probably learned enough to get used to the idea of expansion without a center. Most people just haven't spent enough time thinking about rotating cosmological models to get used to the idea of rotation without a center. As others have pointed out, we don't seem to live in such a Universe: observations give a very strict upper limit on the rotation rate. But such a Universe is theoretically possible, so it's a valid and interesting question to ask why we don't live in one. -Ted -- [E-mail me at name@domain.edu, as opposed to name@machine.domain.edu.]  P: n/a In article <4330052f$0$27407$8fcfb975@news.wanadoo.fr>, jacob navia wrote: >There are other conceptual problems. >Rotation implies a center where the rotation is zero. This is intuitively obvious, so it should come as no surprise that it's not true. In general relativity, there are solutions to the Einstein field equation that describe a Universe that is rotating but that has no center. Specifically, there are homogeneous (but not isotropic) cosmological models in which every point can equally well be regarded as the center of rotation. Remember when you first learned about the expansion of the Universe? Back then, it probably seemed completely obvious that you couldn't have expansion without having a center away from which everything was expanding. After a while, you probably learned enough to get used to the idea of expansion without a center. Most people just haven't spent enough time thinking about rotating cosmological models to get used to the idea of rotation without a center. As others have pointed out, we don't seem to live in such a Universe: observations give a very strict upper limit on the rotation rate. But such a Universe is theoretically possible, so it's a valid and interesting question to ask why we don't live in one. -Ted -- [E-mail me at name@domain.edu, as opposed to name@machine.domain.edu.]
 P: n/a In article <4330052f$0$27407$8fcfb975@news.wanadoo.fr>, jacob navia wrote: >There are other conceptual problems. >Rotation implies a center where the rotation is zero. This is intuitively obvious, so it should come as no surprise that it's not true. In general relativity, there are solutions to the Einstein field equation that describe a Universe that is rotating but that has no center. Specifically, there are homogeneous (but not isotropic) cosmological models in which every point can equally well be regarded as the center of rotation. Remember when you first learned about the expansion of the Universe? Back then, it probably seemed completely obvious that you couldn't have expansion without having a center away from which everything was expanding. After a while, you probably learned enough to get used to the idea of expansion without a center. Most people just haven't spent enough time thinking about rotating cosmological models to get used to the idea of rotation without a center. As others have pointed out, we don't seem to live in such a Universe: observations give a very strict upper limit on the rotation rate. But such a Universe is theoretically possible, so it's a valid and interesting question to ask why we don't live in one. -Ted -- [E-mail me at name@domain.edu, as opposed to name@machine.domain.edu.]  P: n/a In article <4330052f$0$27407$8fcfb975@news.wanadoo.fr>, jacob navia wrote: >There are other conceptual problems. >Rotation implies a center where the rotation is zero. This is intuitively obvious, so it should come as no surprise that it's not true. In general relativity, there are solutions to the Einstein field equation that describe a Universe that is rotating but that has no center. Specifically, there are homogeneous (but not isotropic) cosmological models in which every point can equally well be regarded as the center of rotation. Remember when you first learned about the expansion of the Universe? Back then, it probably seemed completely obvious that you couldn't have expansion without having a center away from which everything was expanding. After a while, you probably learned enough to get used to the idea of expansion without a center. Most people just haven't spent enough time thinking about rotating cosmological models to get used to the idea of rotation without a center. As others have pointed out, we don't seem to live in such a Universe: observations give a very strict upper limit on the rotation rate. But such a Universe is theoretically possible, so it's a valid and interesting question to ask why we don't live in one. -Ted -- [E-mail me at name@domain.edu, as opposed to name@machine.domain.edu.]
 P: n/a In article <4330052f$0$27407$8fcfb975@news.wanadoo.fr>, jacob navia wrote: >There are other conceptual problems. >Rotation implies a center where the rotation is zero. This is intuitively obvious, so it should come as no surprise that it's not true. In general relativity, there are solutions to the Einstein field equation that describe a Universe that is rotating but that has no center. Specifically, there are homogeneous (but not isotropic) cosmological models in which every point can equally well be regarded as the center of rotation. Remember when you first learned about the expansion of the Universe? Back then, it probably seemed completely obvious that you couldn't have expansion without having a center away from which everything was expanding. After a while, you probably learned enough to get used to the idea of expansion without a center. Most people just haven't spent enough time thinking about rotating cosmological models to get used to the idea of rotation without a center. As others have pointed out, we don't seem to live in such a Universe: observations give a very strict upper limit on the rotation rate. But such a Universe is theoretically possible, so it's a valid and interesting question to ask why we don't live in one. -Ted -- [E-mail me at name@domain.edu, as opposed to name@machine.domain.edu.]  P: n/a In article <4330052f$0$27407$8fcfb975@news.wanadoo.fr>, jacob navia wrote: >There are other conceptual problems. >Rotation implies a center where the rotation is zero. This is intuitively obvious, so it should come as no surprise that it's not true. In general relativity, there are solutions to the Einstein field equation that describe a Universe that is rotating but that has no center. Specifically, there are homogeneous (but not isotropic) cosmological models in which every point can equally well be regarded as the center of rotation. Remember when you first learned about the expansion of the Universe? Back then, it probably seemed completely obvious that you couldn't have expansion without having a center away from which everything was expanding. After a while, you probably learned enough to get used to the idea of expansion without a center. Most people just haven't spent enough time thinking about rotating cosmological models to get used to the idea of rotation without a center. As others have pointed out, we don't seem to live in such a Universe: observations give a very strict upper limit on the rotation rate. But such a Universe is theoretically possible, so it's a valid and interesting question to ask why we don't live in one. -Ted -- [E-mail me at name@domain.edu, as opposed to name@machine.domain.edu.]
 P: n/a In article <4330052f$0$27407$8fcfb975@news.wanadoo.fr>, jacob navia wrote: >There are other conceptual problems. >Rotation implies a center where the rotation is zero. This is intuitively obvious, so it should come as no surprise that it's not true. In general relativity, there are solutions to the Einstein field equation that describe a Universe that is rotating but that has no center. Specifically, there are homogeneous (but not isotropic) cosmological models in which every point can equally well be regarded as the center of rotation. Remember when you first learned about the expansion of the Universe? Back then, it probably seemed completely obvious that you couldn't have expansion without having a center away from which everything was expanding. After a while, you probably learned enough to get used to the idea of expansion without a center. Most people just haven't spent enough time thinking about rotating cosmological models to get used to the idea of rotation without a center. As others have pointed out, we don't seem to live in such a Universe: observations give a very strict upper limit on the rotation rate. But such a Universe is theoretically possible, so it's a valid and interesting question to ask why we don't live in one. -Ted -- [E-mail me at name@domain.edu, as opposed to name@machine.domain.edu.]  P: n/a In article <4330052f$0$27407$8fcfb975@news.wanadoo.fr>, jacob navia wrote: >There are other conceptual problems. >Rotation implies a center where the rotation is zero. This is intuitively obvious, so it should come as no surprise that it's not true. In general relativity, there are solutions to the Einstein field equation that describe a Universe that is rotating but that has no center. Specifically, there are homogeneous (but not isotropic) cosmological models in which every point can equally well be regarded as the center of rotation. Remember when you first learned about the expansion of the Universe? Back then, it probably seemed completely obvious that you couldn't have expansion without having a center away from which everything was expanding. After a while, you probably learned enough to get used to the idea of expansion without a center. Most people just haven't spent enough time thinking about rotating cosmological models to get used to the idea of rotation without a center. As others have pointed out, we don't seem to live in such a Universe: observations give a very strict upper limit on the rotation rate. But such a Universe is theoretically possible, so it's a valid and interesting question to ask why we don't live in one. -Ted -- [E-mail me at name@domain.edu, as opposed to name@machine.domain.edu.]
 P: n/a In article <4330052f$0$27407$8fcfb975@news.wanadoo.fr>, jacob navia wrote: >There are other conceptual problems. >Rotation implies a center where the rotation is zero. This is intuitively obvious, so it should come as no surprise that it's not true. In general relativity, there are solutions to the Einstein field equation that describe a Universe that is rotating but that has no center. Specifically, there are homogeneous (but not isotropic) cosmological models in which every point can equally well be regarded as the center of rotation. Remember when you first learned about the expansion of the Universe? Back then, it probably seemed completely obvious that you couldn't have expansion without having a center away from which everything was expanding. After a while, you probably learned enough to get used to the idea of expansion without a center. Most people just haven't spent enough time thinking about rotating cosmological models to get used to the idea of rotation without a center. As others have pointed out, we don't seem to live in such a Universe: observations give a very strict upper limit on the rotation rate. But such a Universe is theoretically possible, so it's a valid and interesting question to ask why we don't live in one. -Ted -- [E-mail me at name@domain.edu, as opposed to name@machine.domain.edu.]  P: n/a In article <4330052f$0$27407$8fcfb975@news.wanadoo.fr>, jacob navia wrote: >There are other conceptual problems. >Rotation implies a center where the rotation is zero. This is intuitively obvious, so it should come as no surprise that it's not true. In general relativity, there are solutions to the Einstein field equation that describe a Universe that is rotating but that has no center. Specifically, there are homogeneous (but not isotropic) cosmological models in which every point can equally well be regarded as the center of rotation. Remember when you first learned about the expansion of the Universe? Back then, it probably seemed completely obvious that you couldn't have expansion without having a center away from which everything was expanding. After a while, you probably learned enough to get used to the idea of expansion without a center. Most people just haven't spent enough time thinking about rotating cosmological models to get used to the idea of rotation without a center. As others have pointed out, we don't seem to live in such a Universe: observations give a very strict upper limit on the rotation rate. But such a Universe is theoretically possible, so it's a valid and interesting question to ask why we don't live in one. -Ted -- [E-mail me at name@domain.edu, as opposed to name@machine.domain.edu.]
 P: n/a In article <4330052f$0$27407$8fcfb975@news.wanadoo.fr>, jacob navia wrote: >There are other conceptual problems. >Rotation implies a center where the rotation is zero. This is intuitively obvious, so it should come as no surprise that it's not true. In general relativity, there are solutions to the Einstein field equation that describe a Universe that is rotating but that has no center. Specifically, there are homogeneous (but not isotropic) cosmological models in which every point can equally well be regarded as the center of rotation. Remember when you first learned about the expansion of the Universe? Back then, it probably seemed completely obvious that you couldn't have expansion without having a center away from which everything was expanding. After a while, you probably learned enough to get used to the idea of expansion without a center. Most people just haven't spent enough time thinking about rotating cosmological models to get used to the idea of rotation without a center. As others have pointed out, we don't seem to live in such a Universe: observations give a very strict upper limit on the rotation rate. But such a Universe is theoretically possible, so it's a valid and interesting question to ask why we don't live in one. -Ted -- [E-mail me at name@domain.edu, as opposed to name@machine.domain.edu.]  P: n/a In article <4330052f$0$27407$8fcfb975@news.wanadoo.fr>, jacob navia wrote: >There are other conceptual problems. >Rotation implies a center where the rotation is zero. This is intuitively obvious, so it should come as no surprise that it's not true. In general relativity, there are solutions to the Einstein field equation that describe a Universe that is rotating but that has no center. Specifically, there are homogeneous (but not isotropic) cosmological models in which every point can equally well be regarded as the center of rotation. Remember when you first learned about the expansion of the Universe? Back then, it probably seemed completely obvious that you couldn't have expansion without having a center away from which everything was expanding. After a while, you probably learned enough to get used to the idea of expansion without a center. Most people just haven't spent enough time thinking about rotating cosmological models to get used to the idea of rotation without a center. As others have pointed out, we don't seem to live in such a Universe: observations give a very strict upper limit on the rotation rate. But such a Universe is theoretically possible, so it's a valid and interesting question to ask why we don't live in one. -Ted -- [E-mail me at name@domain.edu, as opposed to name@machine.domain.edu.]
 P: n/a In article <4330052f$0$27407\$8fcfb975@news.wanadoo.fr>, jacob navia wrote: >There are other conceptual problems. >Rotation implies a center where the rotation is zero. This is intuitively obvious, so it should come as no surprise that it's not true. In general relativity, there are solutions to the Einstein field equation that describe a Universe that is rotating but that has no center. Specifically, there are homogeneous (but not isotropic) cosmological models in which every point can equally well be regarded as the center of rotation. Remember when you first learned about the expansion of the Universe? Back then, it probably seemed completely obvious that you couldn't have expansion without having a center away from which everything was expanding. After a while, you probably learned enough to get used to the idea of expansion without a center. Most people just haven't spent enough time thinking about rotating cosmological models to get used to the idea of rotation without a center. As others have pointed out, we don't seem to live in such a Universe: observations give a very strict upper limit on the rotation rate. But such a Universe is theoretically possible, so it's a valid and interesting question to ask why we don't live in one. -Ted -- [E-mail me at name@domain.edu, as opposed to name@machine.domain.edu.]