plzplzplz dun discuss physics here!!! or make another thread for this if u like, atleast i'll know not to open it..
@mav First of all you cannot equate mc² to H(nu). Reason: m is the rest mass of the particle; when it is not traveling at the velocity of light. When a particle approaches the velocity of light its mass increases (sp. theory of relativity; lorentz transformation eqns; variation of mass) and at 'c', it becomes infinite, which is impossible. To prove my point further........ Are you familiar with the concept of momentum four-vector (Direct derivation from Lorentz transformation eqns.) from special theory of relativity.....Please acquaint yourself with this detail before reading it. From the four-velocity vector (Vi) and the rest mass Mo which is invariant, another four-vector is constructed (momentum) in the direction of the tangent to time track (Minkowski's space): i.e. (Pi)=Mo(Vi) ------(1) It is analogue to the momentum in classical mechanics i.e. Pi = MVi(i=123) Eqn (1) represents "momentum four-vector". The norm of this vector is given by: PiPi = Mo(Vi)Mo(Vi) = Mo²ViVi = -Mo²C² ----------(2) since ViVi = u²/(1-u²/c²)-c²/(1-u²/c²) = C² The norm of the four vector is less than zero which shows that this is a time like vector and is parallel to (Vi). Its spatial and temporal parts are: (Pi) = Mo(Vi) = [Mou/√1-u²/c²,iMoc/√1-u²/c²] -------------(3) Since we know that mass ofa particle varies with velocity (sp. theory of relativity; lorentz transformation eqns; variation of mass) according to the relation: M = Mo/√1-u²/c² Hence the momentum for vector can be written as: (Pi) = [Mu,iMc] = [p, imc²/c] = [p,iE/c] ---------(4) Where P is the three -dimensional momentum of the particle and E(=mc²) is the total energy of the particle. Thus four-momentum also includes total energy. Thus the norm of eqn (4) gives: PiPi = P²-E²/C² and equating it to the norm from eqn (2) gives: P²-E²/C² = -Mo²C² -------------(5) using eqn (5), particles are categorised into three groups: (1)-- Particles for which E² > P²C² For such particles we have: Mo²C~4 = E²-P²C² > 0 (~ stands for: raised to the power) i.e. M0² > 0 Thus for all such particles the rest mass Mo is positive and real and their velocities less than c. (All material particles fall under this category). (2)-- Particles for which E² = P²C² For such particles we have: E²-P²C² = Mo²C² = 0 i.e. Mo = 0 Thus for all such particles rest mass (Mo) is zero. These particles move with the velocity of light. Photons and all the four types of neutrinos come under this category. The momentum of such particles is independent of velocity and is measured by P = E/C (3)-- Particles for which E² < P²C² For such particles we have: E²-P²C² = Mo²C² < 0 i.e. Mo is -ive Thus rest mass for these particles is imaginary. The velocity of these particles is always grater than the velocity of light. These are hypothetical particles called Tachyons. Thus by conclusion (2) it is clear that a photon or any neutrino that travels at the velocity of light has zero mass. You can confirm all of this from any Physics book, which includes mechanics and Special theory of relativity (Resnic Haliday [if I remember correctly], recommended).
@tejas E=MC² does not represent the total energy of a photon. It represents the amount of energy that would be produced if a particle of rest mass 'M' is projected at the velocity of light 'C'
hows SVITS rock for my college band? SVITS is my coll's name....it actually sounds like swizz rock....hehe btw Estoria is nice...
well, a photon does have mass when its moving. Only its rest mass is zero (rest mass = mass when it is not moving) in the formula e=mc^2, we do not use rest mass. Insted we use the effective mass (mass:when its moving) effective mass = rest mass * gamma where gamma depends on the u :velocity(relative to the observer) of the particle in question. gamma = 1/ [1-(u/c)^2] ; for a photon, u = c so gamma = infinity so its effective mass = rest mass * gamma = 0 * infinty the mass of a photon is calculated as E=mc^2 = hv ; where v=frequency => m= hv/(c^2) or h/(c*lambda) ; where lambda=wavelength. hope it satisfies u luv -nitin
How bout "Escalator Safety" for a bands name. Not so serious but its hilarious. The other day, I was at the subway and I saw a palmflet for 'escalator safety'. lol. A whole palmflet on how to be safe when using an escalator. However, it can be useful. My grandmother is always afraid of using an escalator. Anyways, "ESCALATOR SAFETY"
