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#19
Apr1604, 02:45 PM

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PF Gold
P: 5,533

Energy has no reality apart from its (mathematical) functional dependence on state variables that do have reality (see my post to Les above). 


#20
Apr1704, 07:12 PM

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PF Gold
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Thank you. I appreciate all the responses. This was the clarification I was looking for.



#21
Apr1704, 08:06 PM

P: 618

Tom Mattson siad:
"Velocity is measured, from which kinetic energy is calculated. Temperature is measured, from which thermal energy is calculated. Position relative to a mass is measured, from which gravitational potential energy is calculated. Frequency of a photon is measured, from which photonic energy is calculated." I don't understand the distinction you're making. What's special about velocity? Why can't I say, "Distance and time are measured, from which velocity is caculated"? In fact, can't I even work everything back to just length and say that's the only state variable, and everything else is just a definition or a mathematical abstraction based on length? But why would I want to do that? 


#22
Apr1704, 10:35 PM

P: 137

photons are both a particle and an energy wave. Depending on the circumstances



#23
Apr1804, 03:49 AM

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PF Gold
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#24
Apr1804, 02:07 PM

P: 169

I suggest, in layman's terms, that energy is simply motion. It is not the ability of motion, but rather the motion itself.
Matter/Motion comprise the physical universe, and they are so intertwined, one does need to turn to 'art' or 'artistic expression' to gain a full picture, I dont think scientific literature can cover it enough for the layman without the layman stumbling upon paradox. Motion and energy seduces us to discover it's source, so it takes us into the quantum realm, which becomes even more paradoxical.. Motion is everywhere the center, while matter is the circumfrence nowhere can be found...(and that's poetic ;0) Moonrat 


#25
Apr1804, 04:42 PM

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PF Gold
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Thank you for the suggestion. 


#26
Apr1804, 05:52 PM

P: 169

perhaps this motion can be quantified, perhaps, by 'omnidirection', unidirection, and nondirection? (ternary quantifications are always pretty) 


#27
Apr2004, 01:55 AM

P: 5,625




#28
Apr2004, 02:07 AM

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PF Gold
P: 5,533

The problem with Moonrat's identification is that the term "motion" is already attached to a very different concept, namely that of velocity. Energy is not the same as velocity. The two have different units, and are described by different dynamical laws.



#29
Apr2004, 03:24 AM

P: 137

If motion is energy then a PARticle of light travelling light speed would have infinite energy???? I think I just figured out why there is an uncertainty principle. Because if you know the exact position of that photon and know its exact speed(light) then it is disobeying the laws of physics!!!! Score one for d=E(t)



#30
Apr2004, 04:22 AM

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PF Gold
P: 10,428

PRyckman:
A) The energy of a particle always given by [itex]E = \sqrt{p^2 c^2 + m_0^2 c^4}[/itex]. Photons have no restmass, so [itex]m_0[/itex] is 0. That collapses the equation down to just [itex]E = pc[/itex], where p is the momentum carried by the photon. Photons do not have infinite energy. B) You cannot simultaneously know the position and momentum of a photon to a precision that would violate the uncertainty relation. C) Do not post your personal theories in the general physics forum.  Warren 


#31
Apr2004, 05:09 AM

P: 137

ok sorry, got ahead of myself. But if you could measure that photon's momentum and place at the same time without interacting with it. Would it's M make it an impossibility?



#32
Apr2004, 05:11 AM

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PF Gold
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You can't measure a photon's momentum and position to infinite precision at the same time.
 Warren 


#33
Apr2004, 05:15 AM

P: 137

What are the observations of it's speed, I ask you ,You know it must exist somewhere in there in probability. So If it were possible, what would your calculations show, objevtively



#34
Apr2004, 05:16 AM

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PF Gold
P: 10,428

Are you asking "how do you know light travels at c?"
 Warren 


#35
Apr2004, 05:18 AM

P: 137

No I am asking, If you knew Where a photon was at a given time, and knew it's momentum to be c would that violate the laws of physics, other than the uncertainty principle



#36
Apr2004, 05:23 AM

P: 5,625

This would be a big help to those people who get hung up on grasping the concept. It explains alot about the interconvertability of the different forms, and hence about the conservation of energy. The motion of one thing gets transferred to another and to another: the kinetic motion of a coil relative to a conductor causes the motion of electrons that cause the motion of their electric fields which results in the motion of photons. Is it not safe to say that all things which are in motion have energy, and that all things that have energy are in motion? (Potential energy = potential motion, of course.) 


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