- #1
Rahul Mohan P
- 21
- 0
Hi All;
I was trying to understand Lorentz Transformation equation and special theory of relativity, but as I compared the derivation with a thought experiment which I imagined I found the whole Lorentz Transformation Equation fails. The details of the problem is given below. I know I m wrong but I wish you help me to find where I went wrong.
Thought Experiment Details
PLEASE SEE THE FIGURE ATTACHED
Let us consider a spacecraft moving with a velocity v m/s, two observers are there, one inside the spacecraft (observer-1) and other watching spacecraft from Earth (observer-2). Two light sources (L1, L2) are emitted inside the spacecraft from point ‘P’ and point ‘A’ simultaneously as shown in figure. After one second (time with respect to observer-2) the spacecraft moves ‘x’ m. Observer-1 measures light source L1 moved a distance ‘a’ and light source L2 a distance ‘b’, but observer-2 measures L1 moved a distance ‘a1’ and L2 a distance ‘b1’.
From ΔABC Lorentz Transformation Equation can be derived;
Ø x = v*t1................(1)
Ø a = c*t................(2)
Ø a1 = c*t1................(3)
where;
x is the distance traveled by spacecraft in time t1 (t1 is taken as 1 sec for simplicity)
t1 is time w.r.t observer-2
v is velocity of spacecraft
a is distance traveled by L1 in time t as per observer-1
c is speed of light
a1 is the distance traveled by L1 in time t1 as per observer-2
Applying Pythagoras Theorem to ΔABC;
a12 = a2+ x2
(v*t1)2 = (c*t)2 + (c*t1)2
─► (c*t)2 = (c*t1)2 - (v*t1)2
─►t2 = t12 (1- v2/c2)
t = t1√(1- v2/c2).......Lorentz Transformation EquationConsider ΔPQR;
Since L1 and L2 are emitted at same time the distance traveled by both light will be same after a time interval ‘t’ as measured by observer-1, hence;
a = b
From figure the sides PR = AC
Hence from the ΔABC & ΔPQR it is clear that the distance traveled by L1 & L2 measured by observer-2 in time t1 is not equal.
But the distance traveled by L1 & L2 at time ‘t1’ from observer-2 should be equal since speed of light is constant from any frame of reference;
ie;
a1 = c*t1
b1 = c*t1
Since a1≠b1, the only thing which should vary is the speed of light measured from observer-2’s frame of reference.
I was trying to understand Lorentz Transformation equation and special theory of relativity, but as I compared the derivation with a thought experiment which I imagined I found the whole Lorentz Transformation Equation fails. The details of the problem is given below. I know I m wrong but I wish you help me to find where I went wrong.
Thought Experiment Details
PLEASE SEE THE FIGURE ATTACHED
Let us consider a spacecraft moving with a velocity v m/s, two observers are there, one inside the spacecraft (observer-1) and other watching spacecraft from Earth (observer-2). Two light sources (L1, L2) are emitted inside the spacecraft from point ‘P’ and point ‘A’ simultaneously as shown in figure. After one second (time with respect to observer-2) the spacecraft moves ‘x’ m. Observer-1 measures light source L1 moved a distance ‘a’ and light source L2 a distance ‘b’, but observer-2 measures L1 moved a distance ‘a1’ and L2 a distance ‘b1’.
From ΔABC Lorentz Transformation Equation can be derived;
Ø x = v*t1................(1)
Ø a = c*t................(2)
Ø a1 = c*t1................(3)
where;
x is the distance traveled by spacecraft in time t1 (t1 is taken as 1 sec for simplicity)
t1 is time w.r.t observer-2
v is velocity of spacecraft
a is distance traveled by L1 in time t as per observer-1
c is speed of light
a1 is the distance traveled by L1 in time t1 as per observer-2
Applying Pythagoras Theorem to ΔABC;
a12 = a2+ x2
(v*t1)2 = (c*t)2 + (c*t1)2
─► (c*t)2 = (c*t1)2 - (v*t1)2
─►t2 = t12 (1- v2/c2)
t = t1√(1- v2/c2).......Lorentz Transformation EquationConsider ΔPQR;
Since L1 and L2 are emitted at same time the distance traveled by both light will be same after a time interval ‘t’ as measured by observer-1, hence;
a = b
From figure the sides PR = AC
Hence from the ΔABC & ΔPQR it is clear that the distance traveled by L1 & L2 measured by observer-2 in time t1 is not equal.
But the distance traveled by L1 & L2 at time ‘t1’ from observer-2 should be equal since speed of light is constant from any frame of reference;
ie;
a1 = c*t1
b1 = c*t1
Since a1≠b1, the only thing which should vary is the speed of light measured from observer-2’s frame of reference.