🚀 go-pugleaf

In article <1992Aug3.174941.3571@arizona.edu>, wallin@hep7.physics.arizona.edu (Tripp Wallin) writes...
>In article <1992Aug3.200726.18986@u.washington.edu>, jcr@milton.u.washington.edu (Mr. EuStress) writes:
>|> Christopher Neufeld writes
>|> > Velocities don't transform from frame to frame by simple addition,
>|> > but by so-called Lorentz transformations. 
>|> 
>|> Another writes
>|> > Relativity says that you can consider one of
>|> > the systems as stationary (because all inertial frames of reference are
>|> > equivalent), and then the other would be, according to you, travelling
>|> > at twice the speed of light, which is not possible.
>|> 
>|>     Remember my "IF"s -- "if the one system could `observe'
>|>     the other".  The one system cannot observe the other
>|>     because observations can only made within *ONE*
>|>     single (Lorentz transformed) system.  But,
>|>     **observation does not make reality**.
>|>       If two things, both moving near the speed of light,
>|>     hit each other the real velocity is near 2c.
>|>     The observed would be under c, but that observation
>|>     does not change the "reality".
>|>    
> 
> 
>  Okay I'm only an undergraduate with a month of special relativity behind me 
>  so bear with me and flame lightly because I'm gonna take a stab at this.
> 
>  I wonder how you get two objects going near the speed of light to crash into 
>  each other and then get them to go 2c. The only way would be for them to
>  stick
>  to each other as one mass with a unified mass:
> 
>   m1v1 + m2v2 = (m1 + m2)v3 where m1,m2 are the mass of the objects and v1 
    and v2
>   are some velocities near the speed of light. Now according to the above 
    ideas v3
>   should be near 2c. My question is how? If we're dealing with 
    macroscopic masses then

nope.

first of all, this cannot happen;  if you whack two masses into each other
and they stick, the final velocity of the composite mass must be less than
or equal to the greater of the two velocities. Just think about it a while..
suppose two equal mass balls run into each other at v1=v2 in opposite 
directions.  Then the final velocity is zero.  on the other hand, if one 
ball hits the other at rest, the final velocity would be half the initial. 
(given their masses equal).  In any case, the final velocity is not greater
than either of the initial velocities... it just doesn't make sense, 
classically, or relativistically.

if you want a better more detailed description of collisions like this,
you can e-mail me or perhaps someone else on the net will answer it
over the net

>   in a collison like this most of the energy would be lost in heat and other frictional
>   forces. If we're dealing with microscopic or atomic particles then the closer you get
>   these particles to the speed of light the more their mass increases. Now when these two
>   masses meet they create a burst of high energy particles which is often seen in particle
>   acclerators the world around. I really don't think anything could go faster than the speed
>   of light but then I could be wrong.
> 
>   Okay but now a question:
>   Why is it the "speed" of light and not the "velocity" of light? 

speed is a scalar quantity, velocity a vector... there is no one "velocity"
of light, as velocity defines the particular direction the object in
question (in this case the photons) is going.  However, there is just one
definite speed of light, c.

> 
>   Tripp Wallin
>   Physics and Math Undergraduate                      "I'm not a man, I'm an angel...."
>   wallin@hep1.physics.arizona.edu                      - Sun Ra live in London 1990

Todd K. Pedlar
Graduate Student
Northwestern University