You could argue that there is always matter somewhere and a photon will interact with anything and everything so it is never truly 'free' .. is this the point you wish to establish?
I am pointing at the fact that for something to change, Time is a required ingredient. If Time is taken out of the equation, such as the Photon's CLK being at a stand still, then there is NO opportunity for the beginning of any change at all.
Yet the polarized light filter experiments produce changes of the Photon's properties !
The fact that it may be the external object that has Time within its equation that attempts to interact with the Photon, in no way what so ever does this mean that photon can change, unless the Photon as well has Time within its equation.
Therefore, logic says that a Photon's CLK is ticking, and with this being the case, it must also be in motion across the dimension of Time, as well as across the dimension of Space.
QUOTE (Confused2+Aug 22 2006, 09:42 AM)
Momentum was defined by Newton in the 17th century. p = m v . It is a definition therefore not open to modification.
The definition is as useful as it ever was ..
http://hyperphysics.phy-astr.gsu.edu/hbase.../releng.html#c1 E = sqrt( (pc)^2 + (m0c^2)^2) where m0 is the rest mass. Note this is precisely the same as the apparently simpler E = m c^2 but uses only rest mass instead of the (nightmare) 'relativistic mass'.
By using momentum in the 'wrong' way it just seems that you don't understand the meaning of the word.
The " EARTH " was once flat in the minds of many, but then later on " EARTH " was redefined as a sphere.
Concerning momentum, I am exposing the Momentum of objects, but in this case by adding one additional dimension to the view.
If you choose to remain on the " FLAT " world, so bit it. But as for myself, I choose to expand my awareness, and not let yesterdays understandings hold me back.
QUOTE (Confused2+Aug 22 2006, 09:42 AM)
You could invent a new word (say) 'flop' and say that flop (by definition) = c^2 . I don't think this would get either of us any further forward. The
current understanding of spacetime is explained (a bit) here
http://en.wikipedia.org/wiki/Spacetime
Again, I rest my case !
You say " The current understanding of spacetime.. ", and so in short you are saying that there is a chance that in some tomorrow, more will be learnt about that " spacetime ".
What about the Current understanding of " Momentum ", does it not have the same rights ?
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