"Eoghan" wrote in message
...
| Hi!
| I have a question about simultaneity. Suppose there is a person S
| looking at a person S'. S' is moving with a velocity v=c/2, where c
| is
| the speed of light. In the reference of S' there is a lamp at a
| distance l. The lamp is turned on: according to S', how much time
| does
| the light take to hit S'?

The same time as it takes to return to S, who is now closer.

'we establish by definition that the "time" required by
light to travel from A to B equals the "time" it requires
to travel from B to A' because I SAY SO. -- Albert Einstein the genius.

That's how the cuckoo malformations were created.
"Thus with the help of certain imaginary physical experiments we
have settled what is to be understood by" (any crap Einstein writes).
If you don't understand it, perform a certain imaginary physical experiment.


| And according to S?

S' sees the light travel a distance x at speed c-v
S sees the light return a distance x-vt at speed c+v.
t_S' = x/(c-v)
t_S = (x-vt)/(c+v)

t_S' = t_S BECAUSE EINSTEIN SAID SO!

'we establish by definition that the "time" required by
light to travel from A to B equals the "time" it requires
to travel from B to A' -- Albert Einstein the genius.

It's all he
http://www.fourmilab.ch/etexts/einstein/specrel/www/
If you don't understand it, perform a certain imaginary physical experiment.


| If I try to solve this I have: according to S' the light travels at a
| constant velocity of c, so it takes l/c time to reach S'.

Ok.

| According to S the light still travels at a velocity of c, but S' is
| moving towards the light at a velocity v=c/2, so the equations of
| motion a
| xS'=(c/2)t

You are getting your xs and ls mixed up.

| xL=-ct+l

What's xL, extra large?


| where xS' is the equation for the motion of S' and xL is the equation
| of motion for the light.
| The light reaches S' when xS'=xL so when t=(2/3)(l/c)


You mean like this?
http://www.androcles01.pwp.blueyonde...rt/tAB=tBA.gif
4 = 12, see?
If you don't understand it, perform a certain imaginary physical experiment.



| Now I solve the problem by applying the Lorentz equations:

No, no, no, we haven't got that far yet. You are jumping ahead.
First understand 4 = 12, then you can derive the cuckoo equations
that Einstein blamed on Lorentz.



t=t'/
| sqr(1-1/4), where t is the time according S while t' is the time
| according to S'. The term (b/c)x' isn't there because x'=0 (according
| to S' the light reaches him at x'=0) 1/4 comes from b^2=v^2/c^2, v=c/
| 2.
| If I solve the equation I get: t=(2/sqr3)t'.
| Why have I got the square root? Shouldn't i get t=(2/3)t' = (2/3)(l/
| c) ?

Only if you are as crazy as Einstein.