- #1
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Rapidity of a particle with speed v can be defined as either
or
The difference is that (2) is a dimensionless hyperbolic angle whereas (1) has the same dimensions as speed (and is nearly equal to speed when small).
Equivalent definitions are
I'd like to know which published authors use which of these definitions. I'm really not interested in authors using geometrised units where c = 1, because then (1)=(2) and (3)=(4).
The small number of books I possesses all use (2) or (4), but the Physics FAQ uses (1).
If you can, I'd like you to reply with a reference of the form
(4) Rindler, W. (2006), Relativity: Special, General, and Cosmological, Oxford University Press, Oxford, ISBN 978-0-19-856732-5, p.53.
c tanh-1(v/c).....(1)
or
tanh-1(v/c).....(2)
The difference is that (2) is a dimensionless hyperbolic angle whereas (1) has the same dimensions as speed (and is nearly equal to speed when small).
Equivalent definitions are
[tex]\frac{c}{2}\log_e \frac{1+v/c}{1-v/c}[/tex].....(3)
[tex]\frac{1}{2}\log_e \frac{1+v/c}{1-v/c}[/tex].....(4)
[tex]\frac{1}{2}\log_e \frac{1+v/c}{1-v/c}[/tex].....(4)
I'd like to know which published authors use which of these definitions. I'm really not interested in authors using geometrised units where c = 1, because then (1)=(2) and (3)=(4).
The small number of books I possesses all use (2) or (4), but the Physics FAQ uses (1).
If you can, I'd like you to reply with a reference of the form
(4) Rindler, W. (2006), Relativity: Special, General, and Cosmological, Oxford University Press, Oxford, ISBN 978-0-19-856732-5, p.53.