Where does light shon across the North Pole go?

[TrueHeart]

Let's say you have two stations a short few miles apart, straddling the actual (not magnetic) North Pole. You shine a strong laser pointer from one station to a target positioned at the other station, employing a precalculated bearing/aim that would hit perfectly true if it weren't for Earth's rotation. Where does it hit? ..and if you're answer is "just west of true" then I question how all of a sudden there's a preferred 'aether' frame with respect to which light moves. Do you think it kind of "defaults" to the next higher 'realm', and behaves as if it's in Earth's center's inertial frame?? Duh.

[YT2095]

if callibrated correctly it would hit dead cetner of its target, over such a short distance and slow rotation, it`ll make no observable diff whatsoever

I really hope you`re not a "aether" Beleiver as well (

[swansont]

Do you think it kind of "defaults" to the next higher 'realm', and behaves as if it's in Earth's center's inertial frame?? Duh.

 

That's a key idea to think about. The rotating earth is not an inertial frame, so one has to be careful when applying special relativity ideas.

 

The beam will be deflected because the target will have moved in the time it takes for the beam to get to the target. Won't be very much, as YT implied. But that really has nothing to do with preferred frames. If you align a laser, turn it off, then start moving the target when you turn it on again, you'll see the same thing, even if it's all in an inertial frame. In fact, a variation on that is how you can measure the speed of light.

[YT2095]

I still maintain it will hit true over that distance (sorry and all that)

[TrueHeart]

You have to tell me where the laser beam will go after it goes beyond the target station, what planet will the beam land on so-to-speak and why. According to what metric of what frame will the beam advance?

[swansont]

I still maintain it will hit true over that distance (sorry and all that)

 

But do a thought experiment and make the separation larger or the rotation faster. At what point would it not hit "true?" And why would it not deviate until that point?

[swansont]

You have to tell me where the laser beam will go after it goes beyond the target station, what planet will the beam land on so-to-speak and why. According to what metric of what frame will the beam advance?

 

According to any inertial observer (say, floating far above the north pole) it will go in a straight line.

[TrueHeart]

Yes but here's the problem: the Earth is gradually encircling the Sun, as is that observer (A) who is 'hovering' over the N.Pole. Since Earth's is a very gradual movement, we'll call it an inertial frame for purposes of a suitably brief snapshot. The Sun's motion WRT our galaxy can likewise be designated as inertial for a suitably small window; and there's an observer (B) hovering over our galaxy. The Milky Way is headed one way, yet the Sun is headed some way perpendicular to that, we'll surmise... AND, the Earth's motion is along yet a third oblique axis when viewed by this new observer B. The narrow laser beam does eventually land on a precise point on some celestial body... let's say on the Moon, just a brief second or two later. And of course, the Moon is seen to be moving along yet another oblique course WRT to all of the foregoing landmarks, per B's observatory.

 

So if the path from the beam's origin to its eventual landing is a straight line per observer A, then wouldn't it be a curved line according to observer B?? Assume that there are only straight-line inertial motions of each entity during the brief 1.3-second window, but they occur in every crazy-which relative direction.

 

Maybe: what one inertial observer perceives as a straight line will transform to be a straight course in the metric of all other inertial frames. I can see a logic to that.

 

But I mean, maybe according to observer B, the carefully-aimed laser beam doesn't appear to be destined to land right at those particular coordinates on the Moon's surface.

[Callipygous]

I still maintain it will hit true over that distance (sorry and all that)

 

it will hit a little bit off given any distance and any movement, the only difference is how much. it will be very very close. probably undetectable by any means we currently possess. (but still off)

[YT2095]

Hmmm... I understand what your getting at now, on a larger scale or faster spin a top down look at the laser would apear as a curve, much like moving a water jet from side to side making a zig-zag patern.

 

I was thinking too literaly like having a laser sight on a riffle and firing, that type of scale the diff wouldn`t be noticable.

I`m with ya now )