[Phys-L] Re: The view from the Enterprise.

["Fayngold, Moses" <fayngold@ADM.NJIT.EDU>]

Longitudinal Lorentz contraction will be the same for objects in front
and in the rear, or in transverse direction. It is an additional effect
independent of the direction to the object.
 The intensity increase in front is due to the sources approaching the
spaceship - it is, in a way, another aspect of the Doppler effect.
By the same token, there shoud be decrease in the brightnes from the rear,
due to the sources retreating from the spaceship.
  There is another interesting effect worth trying to animate - the change
in the background radiation. At a certain speed of the spaceship the peak
in its spectrum as observed on Earth, will be all blue-shifted into the
visible, so even in the absense of stars, dust, and other masssive sources,
the view in front will start gleaming. I would also expect the rear view
darkened and eventually almost totally dark.
  The global anisotropy of the backgound radiation observed from a
relativistic spaceship does not contradict Lorentz-invariance, because it
is due to the motion of the surrounding medium relative to the spaceship,
- not to the change of the laws of nature.

Moses Fayngold,
NJIT

-----Original Message-----
From: Forum for Physics Educators [mailto:PHYS-L@list1.ucc.nau.edu]On
Behalf Of Rick Tarara
Sent: Tuesday, January 17, 2006 10:56 AM
To: PHYS-L@LISTS.NAU.EDU
Subject: Re: The view from the Enterprise.


So far, two major effects, one of which I can easily incorporate--the other
??

1)  As the blue/violet stars would seem to 'go out' they should remain a
very dim 'white'--(dark grey in my animation) because the broad spectrum
infrared radiation has been shifted into the visible.  What about the rear
view.   Is there enough UV intensity to do the same there?

2)  As the space in front seems to contract (to one viewing from the ship)
more stars should come into the view--and fewer in the rear view--as though
the once uniform star field is being stretched away from the rear and being
compressed into the front view.  [I have an idea how to animate that, but
sure how well it will work.]

Anything else major that HAS to be included in something intended for gen-ed
students?

Rick


----- Original Message -----
From: "Fayngold, Moses" <fayngold@ADM.NJIT.EDU>
To: <PHYS-L@LISTS.NAU.EDU>
Sent: Tuesday, January 17, 2006 10:10 AM
Subject: Re: The view from the Enterprise.


> I have so far only one qualitative comment - the one regarding Rick's
> statement that the oncoming light is blue-shifted. This does not
> necessarily mean, however, that the stars in front view will "go out",
> because ALL frequencies undergo this shift, so as the stellar visible
> spectrum (in the galactic rest frame) will shift into UV (in the frame
> of the spaceship), by the same token some of the stellar IR-radiation
> will be blue-shifted into the visible. Even if the ship's velocity
> approaches c, there will always be a region of the stellar spectrum
> (first IR, then radio) blue-shifted into the visible. One could say
> that the stars in front will become invisible anyway due to the drop
> in the intensity of the IR and especially radio-frequency of the
> black-body spectrum; however, together with the blue-shift, the Lorentz
> boost will increase the intensity of the oncoming light in the ship's
> rest frame.
> Which one out of these two opposing effects is stronger, I cannot say
> right now. It needs some quantitative estimation.
>
> Moses Fayngold,
> NJIT
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