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- Path: sparky!uunet!ogicse!decwrl!netcomsv!cruzio!snarfy
- From: snarfy@cruzio.santa-cruz.ca.us
- Newsgroups: sci.physics
- Subject: Defining Photons
- Keywords: Relating photons E=MC^2 criticism
- Message-ID: <3942@cruzio.santa-cruz.ca.us>
- Date: 26 Jul 92 09:00:44 GMT
- Article-I.D.: cruzio.3942
- Sender: news@cruzio.santa-cruz.ca.us
- Reply-To: snarfy@cruzio.santa-cruz.ca.us
- Lines: 58
-
-
- In Messa:ge-ID: <9935@sun13.scri.fsu.edu> J. A. Carr quotes me and
- responds :
-
-
- >> Einstein,postulated that a photon has no ``rest''
- >> mass. We are faced ,then, with the task of relating these
- >> theoretical ``particles'' that do not have a rest masses to the
- >> equation E=Mc^2 since it is assumed that M represents a rest mass
- >> value.
-
- > [ long argument based on wrong equation deleted ]
-
- >The equation is
- > E^2 = m^2c^4 + p^2c^2
-
- >where m is the mass, p is the momentum (vector), E is the total energy,
- >and c is the speed of light. E=mc^2 is a specialized case of this
- >equation, and can be used to tell you the total energy of a massive
- >particle at rest. It should not be applied to a massless particle
- >such as a photon or neutrino.
-
- >For massless particles, it is the case that E=pc.
-
- Your criticism is noted and forwarded to my sources. However my
- personal evaluation is that you are missing the point. When the
- word ``particle'' is both applied to that which has no mass and
- to that which does have mass, we must seriously question the
- choice of words used, for the sake of clarity ,if nothing else .
-
- We are not here trying to ``apply'' the equatiom E=Mc^2 to the
- photon. The stated purpose and idea is to ``relate'' massless
- ``particles'' to the massive ones in the M of E= Mc^2 . If a
- photon has E and E has some relationship to M via E=Mc^2 (or E^2
- = m^2c^4 + p^2c^2) then there must some ``relationship'' that a
- photon has to M that can be expressed or measured. The
- expression E=pc contains no reference to M so that's one reason
- E=Mc^2 was used. The other reason is that we want E on one side
- of the equals sign and not E^2.
-
- >I find it odd that someone can spend a lot of time working on such a
- >document that was posted here and never take the time to read enough
- >of Einstein to know the actual equations he used.
-
- If you are a college professor , the taxpayers or students pay
- you to enlighten and clarify issues pertaining to your specialty.
- Why then have you not yet found a word other than ``particle'' to
- describe that which has no mass , to differentiate it from that
- which does?. I think it's because some of you would prefer to
- confuse people rather than teach them. The photon, as a concept ,
- would be more accurately described as a ``phenomena'' given the
- difficulty you have manipulating it the same way as a
- ``particle'' mathematically. (multiplying by zero ,for one
- thing).
-
- I find it odd that you have a job.
-
- Jim Ostrowski
-