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Deriving Lorentz factor by means of dynamics of gases.
Let's take some fluid medium.
p - pressure
R - density
V - velocity
C - sound speed (in this fluid)
First, let's derive momentum equation (if you know it, you can skip this part).
Let's examine change of momentum of a fluid element:
F1-F2=(dm*v2-dn*v1)/dt
F=p*S, dm/dt=R*S*v
p1*S1-p2*S2=R2*S2*v2^2-R1*S1*v1^2
~ S1(R1+p1*v1^2)=S2(R2+p2*v2^2) ~
Let's denote pressure in free fluid as p0, and suppose that adiabatic exponent is very close to 1. Let's examine moving fluid element:
p+R*v^2=p0
(p/p0)=1-(R/p0)*v^2
c=sqrt(p/R)
(p/p0)=1-(v/c)^2
(c'/c)=sqrt(p/p0)
~~~ (c'/c)=sqrt(1-(v/c)^2)=gamma ~~~
So interaction speed has decreased and all time intervals have stretched: dt=dt0/gamma. Can it be a mere coincidence? It explains two "purely relativistic" effects from etheral point of view:
- Muons reaching earth surface
- Transverse Doppler effect
I'm not sure if above derivation is 100% correct, but at least it's fun ;)
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