Mass-Energy Equivalence
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From: Koobee Wublee on 4 Apr 2010 01:53 On Apr 3, 10:23 pm, Tom Roberts wrote: > Tony M wrote: > > As per the mass-energy equivalence, can I assume the following is > > valid? > > In relativity, which I assume is the context for your question, mass and energy > are not "equivalent" in the manner you seem to think. They are in certain > circumstances inter-convertible, but are most definitely not the same. This is unbelievable. Self-styled physicists came up with (E = m c^2). Now, they are walking away from it and speak with a forked tongue. These clowns are very liberally interpreting the scripture according to their religion. That's what you get for liberal-art schools, I guess. <shrug> > > - electric energy flowing through power lines is equivalent to a mass > > flow => mass is transferred from the source to the load > > No. There is only a rather loose correspondence to mass transfer. Energy is > transferred, not mass, in that you could not detect mass in transit between > them. It is possible to use the increased energy at the load to increase its > mass, and to use the reduced energy at the source to reduce its mass, but there > is no necessity to do so. In many common cases there is no definite object with > a definite mass at source, load, or both, so attempting to discuss "mass > transfer" is useless and perhaps meaningless. Your interpretation of things is merely a philosophical interpretation. <shrug> > > - a charged battery or capacitor has higher mass than a discharged one > > Yes (identical batteries or capacitors). (E = m c^2) compliant response. <shrug> > > - a coil has higher mass when current passes through it > > Yes, if you include the surrounding volume containing the magnetic field. (E = m c^2) compliant response. <shrug> > > - the mass of an object will increase with its altitude > > No. (E = m c^2) compliant response. Since energy is conserved under the Schwarzschild metric, mass must remain the same according to altitude. The mass will increase with speed, but the same mass will decrease at lower altitude. The net result must be nullified. <shrug> > > - the mass of an object will increase with its temperature > > Yes. (E = m c^2) compliant response. <shrug> > > - a spring's mass increases when compressed or stretched > > Yes. (E = m c^2) compliant response. <shrug> > > - compressing a quantity of gas will increase its mass > > Maybe, depending on the details. What details, please? > > To generalize the above, an exchange of energy (of any kind) is > > equivalent to an exchange of mass. > > No. (E = m c^2) NOT compliant response. <shrug> > The pattern above is: given a definite object (or volume contained in an > enclosure), when you put more energy into the object (or enclosure) the mass of > the object (or of the enclosure and contents) increases. Without that, it is not > possible to apply the "equivalence" in any sensible manner. "Enclosure" is a bit > too strong, as the example of the coil illustrates (the magnetic field of the > coil is not enclosed by the coil, but is rigidly connected to it) -- it is more > like "connected" than "enclosed". In another words, we are observing the slight change in mass as Newtonian energies. <shrug> > Note that lifting an object to higher altitude does not put more energy into the > object; in some sense, speaking loosely and in Newtonian terms, that is putting > energy into the gravitational field, not into the object itself. All you have to do is to evoke the conservation of energy under the Schwarzschild metric. <shrug> > Note that in all of the above cases, when there is a change in mass, it is > usually too small to be measurable. > > To see the problem in your attempted generalization, note that the energy of an > object is the time component of its 4-momentum; the mass of the object is the > norm of its 4-momentum. These are quite different concepts, with quite different > properties. In some cases, changing one changes the other correspondingly, but > not in all cases. For instance, throwing a baseball increases the energy of the > baseball (in the frame of the thrower), but does not affect its mass [#]. When a > rocket blasts off, its mass decreases (because it expels mass in the form of > exhaust), but its energy increases (relative to the frame from which it started) > [@]. All you have to say is that energy is relative (and so is mass). <shrug> > [#] There is no enclosure that contains the thrown baseball. > > [@] If you put the rocket into a large box that contains both > the rocket and its exhaust, the total mass of box plus contents > is unchanged by blast off. Would this be the year of the Cubies? Every year I had hoped for but in vain doing going back to my great grandfather's time. <shrug>
From: PD on 5 Apr 2010 14:18 On Apr 4, 12:53 am, Koobee Wublee <koobee.wub...(a)gmail.com> wrote: > On Apr 3, 10:23 pm, Tom Roberts wrote: > > > Tony M wrote: > > > As per the mass-energy equivalence, can I assume the following is > > > valid? > > > In relativity, which I assume is the context for your question, mass and energy > > are not "equivalent" in the manner you seem to think. They are in certain > > circumstances inter-convertible, but are most definitely not the same. > > This is unbelievable. Self-styled physicists came up with (E = m > c^2). Now, they are walking away from it and speak with a forked > tongue. These clowns are very liberally interpreting the scripture > according to their religion. That's what you get for liberal-art > schools, I guess. <shrug> > E=mc^2 in no way implies that mass and energy are equivalent, any more than F=ma implies that force and acceleration are equivalent. The equation relates the quantitative values of two distinct physical variables. That's what equations do. If you cannot read an equation, then perhaps you should read some sentences that precede and follow the equation where it is presented.
From: Sue... on 5 Apr 2010 14:30 On Apr 4, 1:53 am, Koobee Wublee <koobee.wub...(a)gmail.com> wrote: [...] http://en.wikipedia.org/wiki/Electronvolt Relativistic particle dynamics http://farside.ph.utexas.edu/teaching/em/lectures/node126.html Sue...
From: Sue... on 5 Apr 2010 14:35 On Apr 5, 2:18 pm, PD <thedraperfam...(a)gmail.com> wrote: > On Apr 4, 12:53 am, Koobee Wublee <koobee.wub...(a)gmail.com> wrote: > > > > > On Apr 3, 10:23 pm, Tom Roberts wrote: > > > > Tony M wrote: > > > > As per the mass-energy equivalence, can I assume the following is > > > > valid? > > > > In relativity, which I assume is the context for your question, mass and energy > > > are not "equivalent" in the manner you seem to think. They are in certain > > > circumstances inter-convertible, but are most definitely not the same.. > > > This is unbelievable. Self-styled physicists came up with (E = m > > c^2). Now, they are walking away from it and speak with a forked > > tongue. These clowns are very liberally interpreting the scripture > > according to their religion. That's what you get for liberal-art > > schools, I guess. <shrug> > > E=mc^2 in no way implies that mass and energy are equivalent, any more > than F=ma implies that force and acceleration are equivalent. > > The equation relates the quantitative values of two distinct physical > variables. That's what equations do. > > If you cannot read an equation, then perhaps you should read some > sentences that precede and follow the equation where it is presented. <<...an electron and a positron, each with a mass of 0.511 MeV/c2, can annihilate to yield 1.022 MeV of energy.>> http://en.wikipedia.org/wiki/Electronvolt Sue...
From: PD on 5 Apr 2010 14:40
On Apr 5, 1:35 pm, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > On Apr 5, 2:18 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Apr 4, 12:53 am, Koobee Wublee <koobee.wub...(a)gmail.com> wrote: > > > > On Apr 3, 10:23 pm, Tom Roberts wrote: > > > > > Tony M wrote: > > > > > As per the mass-energy equivalence, can I assume the following is > > > > > valid? > > > > > In relativity, which I assume is the context for your question, mass and energy > > > > are not "equivalent" in the manner you seem to think. They are in certain > > > > circumstances inter-convertible, but are most definitely not the same. > > > > This is unbelievable. Self-styled physicists came up with (E = m > > > c^2). Now, they are walking away from it and speak with a forked > > > tongue. These clowns are very liberally interpreting the scripture > > > according to their religion. That's what you get for liberal-art > > > schools, I guess. <shrug> > > > E=mc^2 in no way implies that mass and energy are equivalent, any more > > than F=ma implies that force and acceleration are equivalent. > > > The equation relates the quantitative values of two distinct physical > > variables. That's what equations do. > > > If you cannot read an equation, then perhaps you should read some > > sentences that precede and follow the equation where it is presented. > > <<...an electron and a positron, each with a mass > of 0.511 MeV/c2, can annihilate to yield 1.022 MeV of energy.>>http://en.wikipedia.org/wiki/Electronvolt > > Sue... Yes, indeed. There is the numerical equality I was talking about. Note that a processes where the collision of two objects with mass produces a predictable amount of energy does not imply that mass and energy are equivalent. Perhaps you have the same difficulty that KW is having. |