Re: Simultaneous moments within SR

On Mar 23, 1:15 pm, j...@xxxxxxxx wrote:
On 23 Mar, 17:58, "harry" <harald.vanlintelButNotT...@xxxxxxx> wrote:



<j...@xxxxxxxx> wrote in message

news:1174659175.031890.157350@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

On 23 Mar, 14:48, "Randy Poe" <poespam-t...@xxxxxxxxx> wrote:
On Mar 23, 9:33 am, j...@xxxxxxxx wrote:

How come that during a simultaneous moment, when two beam of light
"fired from the center within the ship", hit the front wall and the
backwall in the ship, they can be spatially separated by a greater
length/distance within the rest space the ship travel.

This is a mystery because i thought the ship was supposed to contract
not expand.

Imagine you marked the position of the back of a moving train at
time 1:00, and the front of the train a minute later. The train
has traveled during that minute. The positions of those two
markers will be farther apart than the length of the train.

Huh, one minute apart and still simultaneous i really do not
understand, you claim you did the markings simultaneous, but separated
in time i do not understand.

Same thing with the light pulses. In the outside frame,
the pulses don't arrive at the front and back of the
rocket simultaneously. So we are marking the front and
back positions at different times, and the resulting
distance is not a measurement of the length.

Hello i thought light should travel invariant through space what are
you talking about.

According to the measurement system of the outside observer, the light
travels invariantly at c in *that* space while the train is moving as well
in that space. Thus, according to that measurement, while the backward going
light moves at c, the train moves at v towards it, so that the light touches
the back of the train as it meets it rather soon because the distance is
reduced.

I hope you realise what you say here you say that the light travels c
+v, if you call this light invariant you have me stumped.

The light travels at c.
The wall travels at v.

Their distance shrinks at a rate v+c. There is nothing actually
moving at that speed.

There is no c+v c-v in relativity,

Yes there is. It is the separation rate, or approaching
rate, of a light beam (always moving at c) and an object
moving at +-v.

- Randy

.

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