Simen Kvaal <sim### [at] studentmatnatuiono> wrote:
: Light has mass. Period!! It's not just a mathematical trick. Light *has*
: relativistic mass, and so have you. When travelling faster and faster, you
: gain weight. You cannot travel at the speed of light, because you'd have
: infinite mass:

: m = m0 / sqrt(1 - (v*v/c*c))

: If m0 is your resting mass, v is your velocity and c is the speed of light,
: then relativistic mass (aka REAL mass) is m. You can see from the equation
: that when your speed approaches the speed of light, your mass diverges into
: infinity. These are the equations Einstein found, and they have been
: *empirically* verified!

  Actually it was Lorentz who first proposed the relativistic transformation
of distances with the factor 1/sqrt(1-v*v/c*c). Einstein always refers to
the Lorentz transformations.

: Light has energy, right? Then, light must have mass. It cannot have resting
: mass, because light doesn't rest.

  Well, the actual reason why it cannot have resting mass is because it
wouldn't travel at speed c if it had.

  Now tell me something:
  When light travels through matter (for example water), it travels at a
speed which is less than c. Because of this, the factor 1/sqrt(1-v*v/c*c)
gets a non-infinite value, which multiplied with the rest mass of the
light gives us 0. This would mean that the energy of the light travelling
through water would be 0.
  How is this possible?

:>reason why light bends near massive objects is because the space is curved
:>there and the light tends to move along the geodesic lines of the space
:>(which are actually the shortest way from one point to another). The
:>massive object doesn't attract the light, it's just bending the space.
:>

: Correct, afaik.

  Is the bending of the light caused by the curvature of the space,
the mass of the light (which the massive object attracts), or both?
  If both, then it would seem that the light would not stay in the
geodesic line because the massive object is attracting it out of that line.

: Okay. I was wrong there. But light has mass! The solar winds was just a
: (very) bad example. You can verify that photons actually may cause pressure!
: This is the empirical prof of the mass of light. You cannot have pressure
: without mass.

  How can I verify that photons may cause pressure?

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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