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Everything posted by pmb

  1. pmb


    The definition which nefver needed changing is the way mass was defined by newton and how his second law was defined. Newton defined mass so as to be consistent with the m in p = mv. Plug in c for a photon and you get p = mc. Or if we follow French we'd get From Special Relativity, A. P. French, MIT Press, page 20 The nice thing is that m = p/v is a definition whereas m = E/c2 is an equality. One that doesn't hold true in all concievable cases. E.g. the inertial energy density and the inertial mass density can be different. E.g. consider a rod which is under stress. In such a case the inertial mass density is not the same as the inertial energy density. If you have Schutz's GR text please see page 110 They have zero proper mass but the dop have inertial mass m = p/c. This comes fom the definition of mass which is implicitly defined through the relation p = mv. Such a definition says "mass m is defined such, for a system of particles, mv is a conserved quantity." This might be of use - http://home.comcast.net/~peter.m.brown/sr/inertial_mass.htm The expressioin m = m0 /sqrt(1 - v2/c2)[/size] is not one I choose to use to define the mass of a luxon (a particle whose speed is c)
  2. This could go on forever. I don't see a day that where everyone would decide on when they've arrived at a solutio. I'm not sure when to explain the solution. Perhaps I could point to a relativity text which would give you a hint to the solution if you'd like. Here is a list of the ones I have. http://home.comcast.net/~peter.m.brown/ref/physics_textbooks.htm I could also point to an article in the American Journal of physcs which has a similar problem with the electric field. They won't give the answer but it should head you off to the right direction. Do any of you have the text Gravity From The Ground Up by Bernard F. Schutz? When would you like to see the answer, if at all?
  3. Quite interesting! I've never see it written that way and didn't recognize it. Thanks!
  4. That relation is not a strict Heisenberg relationship. It doesn't mean that energy can't be measured precisely. Recall the derivation of that expression and the meaning of E in it. http://home.comcast.net/~peter.m.brown/qm/time_energy_hup.htm See also http://arxiv.org/abs/quant-ph/9807058 There is no such thing as uncertainty in time. A real Heisenberg expression requires two observables, Time is not an observable and as such there is no time operator. Time is a paramenter. juanrga - Excellant!! Way to go! You"ve got it precisely right in my opinion. Some people were making those kinds of arguements to me a long time ago. I found that a lot of people misuse that relationship that swansont. I also found that those people didn't understand time. They thought it was an observable. Griffiths has a nice insight into this. From Introduction to Elementary Particlesby DAvid Griffiths, 2004). See page 51-52, regarding that relation Oh how I love that quote!
  5. pmb


    The term matter is a term which I tend to stear clear of. If I use it I mean more or lass "stuff". I'd never use it in a scientific sense myself. But if people ask me for a definition in a relativity context I quote Einstein.
  6. I agree. Where did you get the idea that what I said implied differently? I dsagree. This time let's simply refer to the dictionary and be done with it. From http://dictionary.reference.com/browse/faith http://www.thefreedictionary.com/faith http://www.thefreedictionary.com/believe I sent you the URL http://plato.stanford.edu/entries/faith/. Did you take a brief look at it? I can't quote them all since the word belief appears in that page 80 times. Pete
  7. pmb


    Einstein defined matter as follows. From The Foundations of the General Theory of Relativity, by Albert Einstein, Annalen der Physik, 49 (1916). Reprinted in The Principle of Relativity, Dover Pub. See bottom of page 143. Regarding whether photon's have mass please see http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html which explains that Photons have zero proper mass and non-zero inertial mass. Particle physicists have a strong tendancy to use the term "mass" to mean "proper mass". They don't have applications otherwise. It's different when working with continuous media. Cosmologists use the term differently such as when it comes to gravitational mass.
  8. I my humble oinion, faith is beleving something that you don't know to be true. For exmaple; a man may have faith that his wifeisn't cheating on him when she's not in his presence. Yes. Sometimes this proves false. A particulr physicist may have faith that a particular element was discovered after readingaout it i s science journal. And yes again. Sometimes this has been proven false too. The question is what you believe it means. Not what we find that we'd think you mean. For that reason its up to you to do the work.
  9. Have you ever looked up the meaning of the word physics in a dictionary? If not then please see http://www.merriam-webster.com/dictionary/physics You'e confusing the defintion that readily comse to mind when you're talking to physicists to the physics properties of the universe. When you do this intentionaly withot stating so then you are intentionally being misleadingwith you make the above clam.
  10. Hint: What is the energy density of a magnetic field? Question: What units are you using?
  11. Hint: I'm staying out of this thread for most of it. But consider the following regarding your expression [math]\rho_i \equiv \sqrt{(T^{00})^2 - (T^{i0})^2}[/math]
  12. Thank's for responding. re - It's tricky to know what exactly you're asking for. - I'm asking that people take a crack at solving this problem. It's the same question asked in the SR text I mentioned, i.e. from Special Relativity: A Modern Introduction by Hans C. Ohanian, Physics Curriculum & Instruction, 2001, page 149, problem 14. So basically the question I posed is to solve this problem. Let's wait until we get multiple responses before I comment on the answers. Of course, there is a good reason why I chose this problem and why I called it challenging. Pete ps - If you don't want to wait then let me know and I'll PM you my comments.
  13. People often ask me about when proper mass can't work as good as relativistic mass or even better. I wrote an entire paper to answer this question but people don't read it carefully enough. Probably because they believe that no matter what the paper says they've already made up their mind because the already thought about it carefully alread a long time ago. And that is a good reason. I'd probably do the same thing - Too much reason with no real expectations of changing what they think in any sape or form So to take a shot at perhaps clarifying why physicists hold on to the notion of relativist mass. So I've decided to create a challenge for everyone. I have a SR text by Hans C. Ohanian. One of the homework problems is to find the mass density of a magnetic field. That's my challenge to you all. Solve this introductory level SR problem. Let's make it as simple as possible and assume that the magnetic field be uniform. Find the mass density of a the magnetic field. Use whatever definition of mass that you see fit. Good luck.
  14. Awesome screen shot! However I don't see that on the web page on my screen. Were should I be looking for it? Pete
  15. I'm in rely mode now. I don't know what the "ribbon/toolbar" is. Splain please!
  16. I hear so many religious leaders claim that God exists out of time. Here is an example of their belief. No logical arguement has ever been given in m experience. See Does God exist outside of time and sees all of time at once. at http://lavistachurchofchrist.org/LVanswers/2008/11-09.html This particular author seems inteligent enough to know better. E.g. her quotes the following It warms the heart to hear someone in religion is intelligent. Others just can't get their mind on what it means to exist outsie of time. I'd betcha that none of them has ever spoken to a physicist or a philosopher of science. lol!
  17. I'm using the same browser that I always have for the last 12 years, Internet Explorer. They used to how up with this browser but not now.
  18. Thank you. I am truly honored. Do you think that you can help me?. I can't get the Emoticons on the right panel back. Clicking on Show All does nothing. If I had an Emoticon I'd click on the one that makes me look sad. LOL!!
  19. I don't see any reason to assume that the momentum is unbalanced. When the EM wave hits the piece of iron the iron radiates an EM wave in all directions, not just back to the source. The stress wave inside the frame does not move at c so it hits the magnet later. When the wave hits the magnet it will stimulate another EM wave and it goes on and on. The momentum of any system is always conserved. See http://home.comcast.net/~peter.m.brown/em/momentum_of_radiation.htm
  20. I just looked up the term "name-dropping". From http://www.thefreedictionary.com/name-dropping Let me state this now and perhaps I'll come to terms with it. The purpose of my posting a quote from Guth had nothing to do with implying anything about my familiarity wih Dr. Guth. The purpose was physics related and not fame related. As if I'd ever become famous by name-dropping here. LOL!! Although now that I think back ... I did do a bit of shameful name-dropping here. It was more along the way of being proud to know and work with them. After all that part is in print so ...
  21. Yep! Sure did. Thanks. However the Emoticons are still blank. Any thoughts?
  22. The limit of E is the total energy of the universe (if such a thing exists) so an irrational amount of energy would be more energy that exists. There's always the scenario where a tardyon (which always moves at the speed of light) moves faster than light. The energy of the particall would be conceptually irrational as well as mathematically a complex number, both of which are nonsense and therefore impossible.
  23. Luke 22:66-70 [66] At daybreak the council of the elders of the people, both the chief priests and teachers of the law, met together, and Jesus was led before them. [67] "If you are the Christ, " they said, "tell us." Jesus answered, "If I tell you, you will not believe me, [68] and if I asked you, you would not answer. [69] But from now on, the Son of Man will be seated at the right hand of the mighty God." [70] They all asked, "Are you then the Son of God?" He replied, "You are right in saying I am." Good enough for a logical man. Jesus would never have told someone he was the son of God if it wan't true. Jesus never lied! To disagree with that is to be a kind of Christian that Jesus wouldn't want me debating with. Jesus said to bring his news to the town and if a town rejcts you then kick the dirt of the town off your shoes and move on to the next town. Kick, kick, kick!!
  24. <br /><br /><br />No. This doesn't account for gravitational time dilation. Clocks near gravitating bodies which generate a spacetime for which there is a spatial variation in [math]g_00[/math] will cause the local clock to run at a different rate as the distance source. If you locallysync that clock to the distance source then according to distant clocks they will be out of sync.
  25. <br /><br /><br /> The text is on black holes and that is my extent of knowledge. What you're asking about is outside my area of expertise. You want someone versed in quantum gravity. Hopefully someone will chime in. I have a luncheon on friday where I'll be around a lot of experts. I'll raise the question if I remember it.
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