A simple Q. but not a simple A,,
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From: Spencer Spindrift on 26 Dec 2009 18:42 Q.: How is it that a photon has momentum but no mass? Or in other words how does light carry energy? As far as I know momentum is a property of moving or spinning mass. A photon cannot have mass or it would be infinite at C.. A.; ???
From: Sam Wormley on 26 Dec 2009 18:59 On 12/26/09 5:42 PM, Spencer Spindrift wrote: > Q.: How is it that a photon has momentum but no mass? > Or in other words how does light carry energy? > As far as I know momentum is a property of moving or spinning > mass. > A photon cannot have mass or it would be infinite at C.. > > A.; ??? Some properties of photons based on measurements For inertial observers, photons propagate at c From the quantum mechanical perspective 1. photons are emitted (by charged particles) 2. photons propagate at c 3. photons are absorbed (by charged particles) Photon momentum p = hν/c = h/λ Photon Energy E = hν Particle Chart - Standard Model http://www.astro.wisc.edu/~heroux/images/Particle_chart.jpg Conservation of momentum holds. One way to measure photon momentum is to it to measure the change in momentum of what absorbs or emits a photon.
From: Androcles on 26 Dec 2009 19:17 "Uncle Al" <UncleAl0(a)hate.spam.net> wrote in message news:4B36A29B.42C39751(a)hate.spam.net... > Has it occurred to you that more than 100,000 professional physicists > extant plus thousands of physics majors and hundreds of physics grad > students might notice someting was off if a throwback to > knuckle-walking could do it? It has not occurred to you that 100,000 sheep are no match for one dog, knuckle-dragging cretin.
From: Androcles on 26 Dec 2009 19:18 "Sam Wormley" <swormley1(a)gmail.com> wrote in message news:a4qdnUugsu3SPqvWnZ2dnUVZ_rFi4p2d(a)mchsi.com... > On 12/26/09 5:42 PM, Spencer Spindrift wrote: >> Q.: How is it that a photon has momentum but no mass? >> Or in other words how does light carry energy? >> As far as I know momentum is a property of moving or spinning >> mass. >> A photon cannot have mass or it would be infinite at C.. >> >> A.; ??? > > Some properties of photons based on measurements > For inertial observers, photons propagate at c > > From the quantum mechanical perspective > > 1. photons are emitted (by charged particles) > 2. photons propagate at c Bullshit.
From: eric gisse on 26 Dec 2009 19:37
Spencer Spindrift wrote: > Q.: How is it that a photon has momentum but no mass? > Or in other words how does light carry energy? > As far as I know momentum is a property of moving or spinning > mass. > A photon cannot have mass or it would be infinite at C.. > > A.; ??? Fields carry energy and momentum. |