Let's go!
The rocket has just taken off, and is going to join Tau Ceri located
exactly 12 light years from the solar system. The six crewmen (one
American, two French, one Russian, one Chinese, and one Paraguayan) will
reach the star thanks to a sympathetic constant acceleration close to
terrestrial gravity.
We set g=10m/s/s.
We ask how long the shipment will take.

Be careful, never forget Richard Hachel's recommendations: "Warning! The
theory of relativity is very simple, and the calculations hardly go beyond
square roots; but it is stuffed, stuffed, stuffed with little traps".

The rocket's acceleration is ITS acceleration. The first trap to avoid is
not its acceleration seen from the ground.

During the first six months, the acceleration can be considered the same.
But very quickly, the terrestrial frame of reference will notice that the
acceleration clearly tends to decrease.
However, it is indeed the rocket which has its normal acceleration, and
not what the earth will observe of it.

Second pitfall: the spatial zoom effect. The distance left for the rocket
to travel constantly varies with its speed in the sense that the metrics
GET LONGER (this is one of the points that drives relativists the
craziest, since they believe that there is a contraction like Einstein
taught them).

Third trap: The rocket must constantly be considered as fixed in its
reference frame, since there is no privileged reference frame, and it is
Tau Ceti which is approaching the rocket at very high speed, with an
apparent speed of 1.5 c when the rocket is at v=0.6c, and 4c when the
rocket is at v=0.8c.

Note1: the last two traps can be resolved together.

Note2: The rocket never decelerating, it arrives in the state of its
acceleration in the neighborhood of the star.

Answer: 4 years, 9 months and a week approximately (150736591 seconds).

R.H.

Richard Hachel <r.hachel@tiscali.fr> wrote:
> Let's go!
> The rocket has just taken off, and is going to join Tau Ceri located
> exactly 12 light years from the solar system. The six crewmen (one
> American, two French, one Russian, one Chinese, and one Paraguayan) will
> reach the star thanks to a sympathetic constant acceleration close to
> terrestrial gravity.
> We set g=10m/s/s.
> We ask how long the shipment will take.
>
> Be careful, never forget Richard Hachel's recommendations: "Warning! The
> theory of relativity is very simple, and the calculations hardly go beyond
> square roots; but it is stuffed, stuffed, stuffed with little traps".
>
> The rocket's acceleration is ITS acceleration. The first trap to avoid is
> not its acceleration seen from the ground.
>
> During the first six months, the acceleration can be considered the same.
> But very quickly, the terrestrial frame of reference will notice that the
> acceleration clearly tends to decrease.
> However, it is indeed the rocket which has its normal acceleration, and
> not what the earth will observe of it.

“Normal?”

They are both legitimate values of different properties.

>
> Second pitfall: the spatial zoom effect. The distance left for the rocket
> to travel constantly varies with its speed in the sense that the metrics
> GET LONGER (this is one of the points that drives relativists the
> craziest, since they believe that there is a contraction like Einstein
> taught them).

Why is this a pitfall?

>
> Third trap: The rocket must constantly be considered as fixed in its
> reference frame, since there is no privileged reference frame,

Careful. This is YOUR mistake. SR claims there is no privileged inertial
frame. But the frame in which the rocket remains at rest is not an inertial
frame, is it? Do not be sloppy.

> and it is
> Tau Ceti which is approaching the rocket at very high speed, with an
> apparent speed of 1.5 c when the rocket is at v=0.6c, and 4c when the
> rocket is at v=0.8c.
>
> Note1: the last two traps can be resolved together.
>
> Note2: The rocket never decelerating, it arrives in the state of its
> acceleration in the neighborhood of the star.
>
> Answer: 4 years, 9 months and a week approximately (150736591 seconds).
>
> R.H.
>

--
Odd Bodkin -- maker of fine toys, tools, tables

Richard Hachel wrote:

> Let's go!
> The rocket has just taken off, and is going to join Tau Ceri located
> exactly 12 light years from the solar system. The six crewmen (one
> American, two French, one Russian, one Chinese, and one Paraguayan) will
> reach the star thanks to a sympathetic constant acceleration close to
> terrestrial gravity. We set g=10m/s/s.
> We ask how long the shipment will take.

I believe I did this game once, gives about 6 years to reach the speed of
light, which coincide with the rate of replacement of the human cells in
the body.

Le 17/01/2022 à 21:30, Richard Hachel a écrit :

D=12 ly

g=10m/s² (obviously in the rochet frame).

Question n°1 :
If the acceleration is still constant, when will the rocket (proper time)
arrive in the Tau Ceti system?

Question n°2 :
What will be the speed of this rocket observed in the Earth-Tau Ceti
reference frame?

Question n°3: What will be the acceleration of the rocket seen from the
earth when it enters the Tau Ceti system if this acceleration is still
10m/s² in the reference frame of the rocket?

R.H.

Le 17/01/2022 à 21:30, Richard Hachel a écrit :

D=12 ly

g=10m/s² (obviously in the rochet frame).

<http://news2.nemoweb.net/jntp?Ygmfe18-5H0A8Y_fO24nS8oR-i4@jntp/Data.Media:1>

Question n°1 :
If the acceleration is still constant, when will the rocket (proper time)
arrive in the Tau Ceti system?

Question n°2 :
What will be the speed of this rocket observed in the Earth-Tau Ceti
reference frame?

Question n°3: What will be the acceleration of the rocket seen from the
earth when it enters the Tau Ceti system if this acceleration is still
10m/s² in the reference frame of the rocket?

R.H.
<http://news2.nemoweb.net/?DataID=Ygmfe18-5H0A8Y_fO24nS8oR-i4@jntp>

--
"Mais ne nous y trompons pas. Il n'y a pas que de la violence
avec des armes. Il y a des situations de violence".
Abbé Pierre.

Richard Hachel wrote:

> Question n°1 :
> If the acceleration is still constant, when will the rocket (proper
> time) arrive in the Tau Ceti system?

not the acceleration, but the 1g push will exist, depending on your push
capabilities.

> Question n°2 : What will be the speed of this rocket observed in the
> Earth-Tau Ceti reference frame?

both places, c still. But, when are you people going to arrest Makron,
that wanker? Just stop protesting outside singing, just arrest that
mother lover.

Le 18/01/2022 à 13:26, Richard Hachel a écrit :

>
> D=12 ly
>
> g=10m/s² (obviously in the rochet frame).
>

>
> Question n°1 :
> If the acceleration is still constant, when will the rocket (proper time)
> arrive in the Tau Ceti system?
>
> Question n°2 :
> What will be the speed of this rocket observed in the Earth-Tau Ceti reference
> frame?
>
> Question n°3: What will be the acceleration of the rocket seen from the earth
> when it enters the Tau Ceti system if this acceleration is still 10m/s² in the
> reference frame of the rocket?
>
> R.H.
> <http://news2.nemoweb.net/?DataID=Ygmfe18-5H0A8Y_fO24nS8oR-i4@jntp>

<http://news2.nemoweb.net/jntp?wB4Ew2DyN1l6HFlLOcAhgNmbacQ@jntp/Data.Media:1>

Question n°4: At what distance is the earth for the rocket at this
precise moment when it enters the stellar system of Tau Ceti at the end of
its uniformly accelerated speed of 10m/s²?

<http://news2.nemoweb.net/?DataID=wB4Ew2DyN1l6HFlLOcAhgNmbacQ@jntp>

R.H.

--
"Mais ne nous y trompons pas. Il n'y a pas que de la violence
avec des armes. Il y a des situations de violence".
Abbé Pierre.

Le 17/01/2022 à 23:21, Chung Haas a écrit :

> the rate of replacement of the human cells in the body.

Et les propos de Lavrov concernant les positions militaires des russes
autour de la frontière ukrainienne.

C'est extraordinaire.

R.H.

On Friday, January 28, 2022 at 5:43:13 PM UTC-7, Richard Hachel wrote:
> Le 18/01/2022 à 13:26, Richard Hachel a écrit :
>
> >
> > D=12 ly
> >
> > g=10m/s² (obviously in the rochet frame).
> >
>
> >
> > Question n°1 :
> > If the acceleration is still constant, when will the rocket (proper time)
> > arrive in the Tau Ceti system?
> >
> > Question n°2 :
> > What will be the speed of this rocket observed in the Earth-Tau Ceti reference
> > frame?
> >
> > Question n°3: What will be the acceleration of the rocket seen from the earth
> > when it enters the Tau Ceti system if this acceleration is still 10m/s² in the
> > reference frame of the rocket?
> >
> > R.H.
> > <http://news2.nemoweb.net/?DataID=Ygmfe18-5H0A8Y_fO24nS8oR-i4@jntp>
> <http://news2.nemoweb.net/jntp?wB4Ew2DyN1l6HFlLOcAhgNmbacQ@jntp/Data.Media:1>
>
> Question n°4: At what distance is the earth for the rocket at this
> precise moment when it enters the stellar system of Tau Ceti at the end of
> its uniformly accelerated speed of 10m/s²?
>
> <http://news2.nemoweb.net/?DataID=wB4Ew2DyN1l6HFlLOcAhgNmbacQ@jntp>
>
> R.H.

All of this is easily calculated using equations here:

https://en.wikipedia.org/wiki/Space_travel_under_constant_acceleration#Expressions_for_covered_distance_and_elapsed_time

You're welcome.