Light speed is constan "c". I am puzzled
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From: Peter Webb on 18 Feb 2010 22:21 "mpc755" <mpc755(a)gmail.com> wrote in message news:fdf74670-8b35-4cbb-87bf-0b7b6ce4e4c2(a)b7g2000yqd.googlegroups.com... On Feb 18, 9:29 pm, Brad Guth <bradg...(a)gmail.com> wrote: > > > > > > Black holes are determined by whether an object's mass is > > > > > contained > > > > > within its Schwarzschild radius, not by how dense it is. r_s = > > > > > 2Gm/ > > > > > c^2. If the solar system had the density of water, it would be a > > > > > black hole. > > > > > > Double-A > > > > > If the mass of an object is contained within a certain radius, > > > > doesn't > > > > that make it more dense than if the mass extends outside of the > > > > radius? > > > > Large masses have large Schwarzschild radii. As a mass gets larger, > > > the density required for it to fit within its S. radius gets less. > > > > Double-A > > > "The Schwarzschild radius (sometimes historically referred to as the > > gravitational radius) is a characteristic radius associated with every > > quantity of mass. It is the radius of a sphere in space, that if > > containing a correspondingly sufficient amount of mass (and therefore, > > reaches a certain density)..." - wikipedia > > > Seems like density matters. What I am asking is if you have a certain > > amount of mass within the Schwarzchild radius which causes the mass to > > become a black hole, if that same mass occupies 10 times the space of > > its Schwarzchild radius then it will not become a black hole. So, the > > overall density of a certain amount of mass matters when determining > > if it will become a black hole or not, correct? > > It really doesn't require all that much density for something the size > of Earth to have a surface gravity force that's greater than 300,000 > km/sec. I think 1.7e8 g/cm3 would do the trick. > > ~ BG The original response I am responding to stated: "Black holes are determined by whether an object's mass is contained within its Schwarzschild radius, not by how dense it is." What I am saying is the density must matter. If the same mass is not contained within its Schwarzchild radius, if in fact that same amount of mass is spread out over 100 times its Schwarzchild radius it will not become a black hole because the matter which is the mass is less dense. _______________________________ No, density doesn't determine if an object is a black hole. Black holes can be as dense (or denser) than neutron stars, or less dense than the earth's atmosphere. What determines if an object is a black hole is whether its mass is contained in its Schwarzschild radius. (I am assuming a non-rotating black hole, as Schwarzschild did in his original paper. The solution of GR for rotating black holes came later). Given that you do not understand the mathematics of black holes, you shouldn't really be trying to tell people who do what the equations say.
From: mpc755 on 18 Feb 2010 22:26 On Feb 18, 10:21 pm, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "mpc755" <mpc...(a)gmail.com> wrote in message > > news:fdf74670-8b35-4cbb-87bf-0b7b6ce4e4c2(a)b7g2000yqd.googlegroups.com... > On Feb 18, 9:29 pm, Brad Guth <bradg...(a)gmail.com> wrote: > > > > > > > > > > > Black holes are determined by whether an object's mass is > > > > > > contained > > > > > > within its Schwarzschild radius, not by how dense it is. r_s = > > > > > > 2Gm/ > > > > > > c^2. If the solar system had the density of water, it would be a > > > > > > black hole. > > > > > > > Double-A > > > > > > If the mass of an object is contained within a certain radius, > > > > > doesn't > > > > > that make it more dense than if the mass extends outside of the > > > > > radius? > > > > > Large masses have large Schwarzschild radii. As a mass gets larger, > > > > the density required for it to fit within its S. radius gets less. > > > > > Double-A > > > > "The Schwarzschild radius (sometimes historically referred to as the > > > gravitational radius) is a characteristic radius associated with every > > > quantity of mass. It is the radius of a sphere in space, that if > > > containing a correspondingly sufficient amount of mass (and therefore, > > > reaches a certain density)..." - wikipedia > > > > Seems like density matters. What I am asking is if you have a certain > > > amount of mass within the Schwarzchild radius which causes the mass to > > > become a black hole, if that same mass occupies 10 times the space of > > > its Schwarzchild radius then it will not become a black hole. So, the > > > overall density of a certain amount of mass matters when determining > > > if it will become a black hole or not, correct? > > > It really doesn't require all that much density for something the size > > of Earth to have a surface gravity force that's greater than 300,000 > > km/sec. I think 1.7e8 g/cm3 would do the trick. > > > ~ BG > > The original response I am responding to stated: > > "Black holes are determined by whether an object's mass is contained > within its Schwarzschild radius, not by how dense it is." > > What I am saying is the density must matter. If the same mass is not > contained within its Schwarzchild radius, if in fact that same amount > of mass is spread out over 100 times its Schwarzchild radius it will > not become a black hole because the matter which is the mass is less > dense. > > _______________________________ > No, density doesn't determine if an object is a black hole. Black holes can > be as dense (or denser) than neutron stars, or less dense than the earth's > atmosphere. What determines if an object is a black hole is whether its mass > is contained in its Schwarzschild radius. If its mass is not contained in its Schwarzchild radius then it is not a black hole because it is less dense. > (I am assuming a non-rotating > black hole, as Schwarzschild did in his original paper. The solution of GR > for rotating black holes came later). > > Given that you do not understand the mathematics of black holes, you > shouldn't really be trying to tell people who do what the equations say.
From: BURT on 18 Feb 2010 23:34 On Feb 18, 7:26 pm, mpc755 <mpc...(a)gmail.com> wrote: > On Feb 18, 10:21 pm, "Peter Webb" > > > > > > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > > "mpc755" <mpc...(a)gmail.com> wrote in message > > >news:fdf74670-8b35-4cbb-87bf-0b7b6ce4e4c2(a)b7g2000yqd.googlegroups.com... > > On Feb 18, 9:29 pm, Brad Guth <bradg...(a)gmail.com> wrote: > > > > > > > > Black holes are determined by whether an object's mass is > > > > > > > contained > > > > > > > within its Schwarzschild radius, not by how dense it is. r_s = > > > > > > > 2Gm/ > > > > > > > c^2. If the solar system had the density of water, it would be a > > > > > > > black hole. > > > > > > > > Double-A > > > > > > > If the mass of an object is contained within a certain radius, > > > > > > doesn't > > > > > > that make it more dense than if the mass extends outside of the > > > > > > radius? > > > > > > Large masses have large Schwarzschild radii. As a mass gets larger, > > > > > the density required for it to fit within its S. radius gets less.. > > > > > > Double-A > > > > > "The Schwarzschild radius (sometimes historically referred to as the > > > > gravitational radius) is a characteristic radius associated with every > > > > quantity of mass. It is the radius of a sphere in space, that if > > > > containing a correspondingly sufficient amount of mass (and therefore, > > > > reaches a certain density)..." - wikipedia > > > > > Seems like density matters. What I am asking is if you have a certain > > > > amount of mass within the Schwarzchild radius which causes the mass to > > > > become a black hole, if that same mass occupies 10 times the space of > > > > its Schwarzchild radius then it will not become a black hole. So, the > > > > overall density of a certain amount of mass matters when determining > > > > if it will become a black hole or not, correct? > > > > It really doesn't require all that much density for something the size > > > of Earth to have a surface gravity force that's greater than 300,000 > > > km/sec. I think 1.7e8 g/cm3 would do the trick. > > > > ~ BG > > > The original response I am responding to stated: > > > "Black holes are determined by whether an object's mass is contained > > within its Schwarzschild radius, not by how dense it is." > > > What I am saying is the density must matter. If the same mass is not > > contained within its Schwarzchild radius, if in fact that same amount > > of mass is spread out over 100 times its Schwarzchild radius it will > > not become a black hole because the matter which is the mass is less > > dense. > > > _______________________________ > > No, density doesn't determine if an object is a black hole. Black holes can > > be as dense (or denser) than neutron stars, or less dense than the earth's > > atmosphere. What determines if an object is a black hole is whether its mass > > is contained in its Schwarzschild radius. > > If its mass is not contained in its Schwarzchild radius then it is not > a black hole because it is less dense. > > > > > (I am assuming a non-rotating > > black hole, as Schwarzschild did in his original paper. The solution of GR > > for rotating black holes came later). > > > Given that you do not understand the mathematics of black holes, you > > shouldn't really be trying to tell people who do what the equations say..- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text - Point mass is infinitely dense or concentrated C squared energy. This is a fundamental particle core.. Mitch Raemsch
From: Brad Guth on 19 Feb 2010 00:27 On Feb 18, 6:40 pm, mpc755 <mpc...(a)gmail.com> wrote: > On Feb 18, 9:29 pm, Brad Guth <bradg...(a)gmail.com> wrote: > > > > > > > > > > > Black holes are determined by whether an object's mass is contained > > > > > > within its Schwarzschild radius, not by how dense it is. r_s = 2Gm/ > > > > > > c^2. If the solar system had the density of water, it would be a > > > > > > black hole. > > > > > > > Double-A > > > > > > If the mass of an object is contained within a certain radius, doesn't > > > > > that make it more dense than if the mass extends outside of the radius? > > > > > Large masses have large Schwarzschild radii. As a mass gets larger, > > > > the density required for it to fit within its S. radius gets less. > > > > > Double-A > > > > "The Schwarzschild radius (sometimes historically referred to as the > > > gravitational radius) is a characteristic radius associated with every > > > quantity of mass. It is the radius of a sphere in space, that if > > > containing a correspondingly sufficient amount of mass (and therefore, > > > reaches a certain density)..." - wikipedia > > > > Seems like density matters. What I am asking is if you have a certain > > > amount of mass within the Schwarzchild radius which causes the mass to > > > become a black hole, if that same mass occupies 10 times the space of > > > its Schwarzchild radius then it will not become a black hole. So, the > > > overall density of a certain amount of mass matters when determining > > > if it will become a black hole or not, correct? > > > It really doesn't require all that much density for something the size > > of Earth to have a surface gravity force that's greater than 300,000 > > km/sec. I think 1.7e8 g/cm3 would do the trick. > > > ~ BG > > The original response I am responding to stated: > > "Black holes are determined by whether an object's mass is contained > within its Schwarzschild radius, not by how dense it is." > > What I am saying is the density must matter. If the same mass is not > contained within its Schwarzchild radius, if in fact that same amount > of mass is spread out over 100 times its Schwarzchild radius it will > not become a black hole because the matter which is the mass is less > dense. That is correct.
From: Brad Guth on 19 Feb 2010 00:29
On Feb 18, 7:21 pm, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "mpc755" <mpc...(a)gmail.com> wrote in message > > news:fdf74670-8b35-4cbb-87bf-0b7b6ce4e4c2(a)b7g2000yqd.googlegroups.com... > On Feb 18, 9:29 pm, Brad Guth <bradg...(a)gmail.com> wrote: > > > > > > > > > > > Black holes are determined by whether an object's mass is > > > > > > contained > > > > > > within its Schwarzschild radius, not by how dense it is. r_s = > > > > > > 2Gm/ > > > > > > c^2. If the solar system had the density of water, it would be a > > > > > > black hole. > > > > > > > Double-A > > > > > > If the mass of an object is contained within a certain radius, > > > > > doesn't > > > > > that make it more dense than if the mass extends outside of the > > > > > radius? > > > > > Large masses have large Schwarzschild radii. As a mass gets larger, > > > > the density required for it to fit within its S. radius gets less. > > > > > Double-A > > > > "The Schwarzschild radius (sometimes historically referred to as the > > > gravitational radius) is a characteristic radius associated with every > > > quantity of mass. It is the radius of a sphere in space, that if > > > containing a correspondingly sufficient amount of mass (and therefore, > > > reaches a certain density)..." - wikipedia > > > > Seems like density matters. What I am asking is if you have a certain > > > amount of mass within the Schwarzchild radius which causes the mass to > > > become a black hole, if that same mass occupies 10 times the space of > > > its Schwarzchild radius then it will not become a black hole. So, the > > > overall density of a certain amount of mass matters when determining > > > if it will become a black hole or not, correct? > > > It really doesn't require all that much density for something the size > > of Earth to have a surface gravity force that's greater than 300,000 > > km/sec. I think 1.7e8 g/cm3 would do the trick. > > > ~ BG > > The original response I am responding to stated: > > "Black holes are determined by whether an object's mass is contained > within its Schwarzschild radius, not by how dense it is." > > What I am saying is the density must matter. If the same mass is not > contained within its Schwarzchild radius, if in fact that same amount > of mass is spread out over 100 times its Schwarzchild radius it will > not become a black hole because the matter which is the mass is less > dense. > > _______________________________ > No, density doesn't determine if an object is a black hole. Black holes can > be as dense (or denser) than neutron stars, or less dense than the earth's > atmosphere. What determines if an object is a black hole is whether its mass > is contained in its Schwarzschild radius. (I am assuming a non-rotating > black hole, as Schwarzschild did in his original paper. The solution of GR > for rotating black holes came later). > > Given that you do not understand the mathematics of black holes, you > shouldn't really be trying to tell people who do what the equations say. You are playing physics semantics. ~ BG |