Re: recoiling photons evidence?

"George Dishman" <[EMAIL PROTECTED]> wrote in message
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>
> "ralph sansbury" <[EMAIL PROTECTED]> wrote in message
> news:[EMAIL PROTECTED]
> >
> > "George Dishman" <[EMAIL PROTECTED]> wrote in message
> > news:[EMAIL PROTECTED]
> > > "ralph sansbury" <[EMAIL PROTECTED]> wrote in message
> > > news:[EMAIL PROTECTED]
> > > >
> > > > "George Dishman" <[EMAIL PROTECTED]> wrote in
message
> > > > news:[EMAIL PROTECTED]
> > > > >
> > > > > "ralph sansbury" <[EMAIL PROTECTED]> wrote in message
> > > > > news:[EMAIL PROTECTED]
> > > > > That is the wrong equation.The correct form is:
> > > > >
> > > > >  E^2 = m^2 * c^4  +  p^2 * c^2
> > > >
> > > > No this is the wrong equation. The correct form is
> > > > E^2 = (m_0)^2 * c^4  +  p^2 * c^2
> > >
> > > Physics these days has generally dropped the old
'relativistic
> > > mass' presentation as anachronistic and confusing.
> >
> >       I hope not.
> >       It is confusing not to make the distinction.
>
> I suggest you read the FAQ pages:

   Interesting  and there does seem to be an acknowledged  split.
I side with the traditional Rindler crowd and against the Baez
crowd for obvious reasons that a distinction should be made.
Also if you look at some common physics texts you will see that
the meaning of  mass in most text books used today is  the total
mass not the relativistic mass or the rest mass.  And if this
shows there is something wrong with the concept of the photon
then so be it.
     Re a solar sail, this involves much stronger magnetic forces
than the absorption of radiation by a distant spacecraft antenna.
. Re the emission of a photon eg by a distant 8Watt transmitter
not produced after the absorption of photons by a reflective
surface, between what and what is the momentum conserved? Between
what and what is the magnetic force associated with light
pressure etc.?

Ralph

 http://math.ucr.edu/home/baez/physics/Relativity/SR/mass.html
>
> http://math.ucr.edu/home/baez/physics/Relativity/SR/mass.html
>
> > You also
> > misunterstood my question. Namely, when you start an
oscillation
> >  of charge in a distant isolated source
> > by thermally exciting bound electrons in tungsten for
example,
> > the oscillating electrons may recoil from one another as you
> > suggest in a random and cancelling manner  but the whole
source
> >  would not be recoiling against anything.
>
> That depends on how you produce the change of temperature.
> If you heat up the tungsten coil of a light bulb by passing
> a current through it, obviously there is no recoil. You need
> to explain how you heat up "distant isolated" material
> thermally.
>
> >    My  point then  is that you cannot use a mathematical
equation
> > that
> > applies to source and reflector together over a small
distance,
> >  as evidence for photon recoil causing a motion of eg an 8
watt
> > transmitter on a distant spacecraft as photons are emitted.
>
> Why not? A photon is just a photon. Either it carries
> momentum or is doesn't.
>
> >   My point is that the evidence for photon recoil in a
receiver and
> > reflector when the source is close cannot be used as evidence
for
> > the case when the source is distant and the energy of the
emitted
> > photons is large enough but the energy of the received
photons is
> > miniscule.
>
> Solar sails are accelerated by recoil from photons from
> the Sun.
>
> > > >   The correct implicit equation I was using was
> > > > m=E/c^2 not m_0=E/c^2.
> > > >    And since p=mv=Ev/c^2
> > > > and mc^2=(m_0)c^2/(1-v^2/c^2)^1/2 you get
>
> Note this gives
>
>   m_r * c^2 = 0 * c^2 / sqrt(0)
>
> or
>
>   m_r = 0/0
>
> which is undefined.
>
> > > > the corrected equation above.
> > >
> > >    The equation you used implies non-zero mass while the
> > > (invariant) mass of a photon is zero, hence the possible
> > > confusion.
> >
> >     The whole concept of the photon is confused and full of
> > contradictions.  There
> > is no such thing as a photon at rest so the mass of the
photon
> > is never zero!!!
>
> Read the FAQ. The term 'rest mass' comes about because
> rest is the condition when the total energy equals the
> invariant mass. The contradiction appears only because
> you have been confused by the terminology, and that is
> precisely why it is being dropped.
>
> > > If you want to use "relativistic mass", it is
> > > best to use that phrase so everyone understands you.
> >
> >  I was using mass in the normative sense or total mass
> >  which can be analysed into the rest mass and the
relativistic
> > mass
> > or whatever else you might desire. You were using mass
> > in the specialized sense of "rest" mass.
>
> No, I am using it in the standard physical sense of
> invariant mass whereas you are trying to use it in
> the 19th century style of the longitudinal component
> of a quantity that has different values in different
> directions but can take the place of Newtonian mass
> in many equations. It is actually a mathematical term
> consisting of the product of the invariant mass and a
> speed-dependent factor.
>
> George
>
>