Seeking a correct explanation for Stellar Abberation
in [Relativity]
|
Prev: How is SR this probability problem explained?
Next: The Infinitely Large Arch (was Re: Three times happening together)
From: Henry Wilson DSc on 29 Mar 2010 18:22 On Mon, 29 Mar 2010 16:05:13 +0200, "Paul B. Andersen" <paul.b.andersen(a)somewhere.no> wrote: >On 21.03.2010 03:06, train wrote: >> On Mar 20, 5:04 am, "Inertial"<relativ...(a)rest.com> wrote: >>> "train"<gehan.ameresek...(a)gmail.com> wrote in message >>> >>> >>>> Ok here is a telescope >>> >>>> | | >>>> | | >>>> | | >>>> | | >>>> | | >>>> | | >>> >>>> Here is the photon entering the telescope >>> >>>> 0 >>>> | | >>>> | | >>>> | | >>>> | | >>>> | | >>>> | | >>> >>>> | | >>>> |0| >>>> | | >>>> | | >>>> | | >>>> | | >>> >>>> OK now did that photon come from a moving source (relative to the >>>> telescope) or a stationary source (relative to the telescope) ? > >Impossible to say. >The speed of the source is irrelevant. >The velocity (direction) of the photon conveys no information about >the velocity of its source. > >>> >>> If it came from a star and is measured measured on earth, then we know that >>> they are relatively moving. >>> >>> If light were simple ballistic particles, then if it was coming from a >>> moving (or stationary)source aimed at a stationary telescope, then slowing >>> it down would *not* change its angle. >>> >>> .<S> >>> . >>> . o >>> . >>> . >>> . / / >>> . >>> . / / >>> . >>> . / / >>> >>> .<S> >>> . >>> . >>> . >>> . o >>> . >>> . / / >>> . >>> . / / >>> . >>> . / / >>> >>> .<S> >>> . >>> . >>> . >>> . >>> . >>> . /o/ >>> . >>> . / / >>> . >>> . / / >>> >>> .<S> >>> . >>> . >>> . >>> . >>> . >>> . / / >>> . >>> . /o/ >>> . >>> . / / >>> >>> .<S> >>> . >>> . >>> . >>> . >>> . >>> . / / >>> . >>> . / / >>> . >>> . /o/ >>> >>> If light were simple ballistic particles, then if it was coming from a >>> stationary source aimed at a moving telescope, then slowing it down *would* >>> change its angle. >>> >>> .<S> >>> . >>> . o >>> . >>> . >>> . / / >>> . >>> . / / >>> . >>> . / / >>> >>> .<S> >>> . >>> . >>> . >>> . o >>> . >>> . / / >>> . >>> . / / >>> . >>> . / / >>> >>> .<S> >>> . >>> . >>> . >>> . >>> . >>> . /o/ >>> . >>> . / / >>> . >>> . / / >>> >>> .<S> >>> . >>> . >>> . >>> . >>> . >>> . / / >>> . o >>> . / / >>> . >>> . / / >>> >>> .<S> >>> . >>> . >>> . >>> . >>> . >>> . / / >>> . >>> . o / >>> . >>> . / / >>> >>> .<S> >>> . >>> . >>> . >>> . >>> . >>> . / / >>> . >>> . / / >>> . o >>> . / / >>> >>> .<S> >>> . >>> . >>> . >>> . >>> . >>> . / / >>> . >>> . / / >>> . >>> . o/ / >>> >>>> If the telescope is aimed so that the photon is going straight down, >>>> where is the sideways velocity of the photon? Why would filling the >>>> telescope with water change the direction of the photon? > >There is none, and it wouldn't. But you just demonstrated in your previous post that a change in speed DOES change the angle. >This idea that a water filled telescope should change the direction >of the light stems from rigid ether theory. If the light is a wave >in an ether, and the ether is moving through the telescope, then >the light should be 'dragged along with the ether' when its speed >is reduced, and thus change its direction. (If this had been correct, >you could measure the speed of the ether by measuring the angle.) >But as we know, that is not observed. >Fresnel tried to explain this apparent paradox with his ether drag >theory. He assumed that the water to some extent drag the ether >along with it, exactly enough to keep the light beam straight. > > >>> >>>> I understandaberrationnow. >>> >>> Evidently not, if you are still asking questions that someone who DID >>> understandaberrationwould know the answers to >> >> I don't see any difference between a moving source and a moving >> telescope, ie they are moving relatively to each other. Both Galilean >> Relativity and SRT agree on this. > >I am not quite sure what you mean by this statement. > >The velocity of the source (star) has no effect on the direction in >which we see the star, it is utterly irrelevant. > >This is very obvious when we observe the light from spectroscopic >binaries. They may have a huge speed relative to each other, yet >we always see them at the same spot, as one star. We don't...but the difference is too small to be observed. >Remember that aberration is the phenomenon that the direction >of light (or any velocity vector) is frame dependent. >So aberration is _always_ between two relatively moving >frames of reference (observers). > >If two observers are observing the same source, the aberration >- that is the difference between the directions in which they >see the source - depend _only_ on their relative speed. >The speed of the source relative to them is irrelevant. > >Stellar aberration is the phenomenon that the direction in >which we see a star changes throughout the year. >That depends on the _change_ of the velocity of the Earth only. >During half a year, this change is twice the orbital speed of >the Earth, which is 3E4 m/s, or 10^-4 c. >So the angle should be ~ v/c = 2*10^-4 rad = 41", which is what is observed. What happens if we observe a star EXACTLY 100 LYs away that just happens to be moving around an orbit that is parallel and identical to Earth's? ____s>____star's orbit ____e>____earth's orbit The star, which appears as a point source of light, is always at rest wrt earth. Why should aberration occur? >http://home.c2i.net/pb_andersen/pdf/aberration.pdf >http://home.c2i.net/pb_andersen/pdf/Stellar_aberration.pdf Henry Wilson... ........A person's IQ = his snipping ability.
From: Henry Wilson DSc on 29 Mar 2010 18:25 On Mon, 29 Mar 2010 22:35:52 +0100, "Androcles" <Headmaster(a)Hogwarts.physics_x> wrote: > >"Paul B. Andersen" <someone(a)somewhere.no> wrote in message >news:4BB11804.2010802(a)somewhere.no... >> On 29.03.2010 16:39, Androcles wrote: >> >> [snip] >> >> Shut up, Androcles. >> You are making noise. Bad boy. >> Didn't you learn in kindergarten not to shout da-da-da ? >> > >" The velocity of the source (star) has no effect on the direction in > which we see the star, it is utterly irrelevant." -- da-da-da Andersen > >" If two observers are observing the same source, the aberration > - that is the difference between the directions in which they > see the source - depend _only_ on their relative speed." .-- da-da-da >Andersen > > >In the frame of the telescope the star moves, which is what is observed >even in the far north of Norway where the Sun goes around the horizon >without setting, da-da-da Tusseladd. It's only 600 miles for you to get >to the Arctic circle, da-da-da Tusseladd. Di you know the Sun is a star, >Tusseladd? > >Gehan don't see any difference between a moving source and a moving >telescope, ie they are moving relatively to each other. Both Galilean >Relativity and SRT agree on this. Poor confused da-da-da Tusseladd >does not accept the PoR. .....but he can bend light poles by dropping an object down the middle and driving past in his car. Henry Wilson... ........A person's IQ = his snipping ability.
From: Androcles on 29 Mar 2010 18:54 "Henry Wilson DSc" <..@..> wrote in message news:94a2r51vclicvpdfdlkp5eroe1a4oer554(a)4ax.com... > On Mon, 29 Mar 2010 22:35:52 +0100, "Androcles" > <Headmaster(a)Hogwarts.physics_x> > wrote: > >> >>"Paul B. Andersen" <someone(a)somewhere.no> wrote in message >>news:4BB11804.2010802(a)somewhere.no... >>> On 29.03.2010 16:39, Androcles wrote: >>> >>> [snip] >>> >>> Shut up, Androcles. >>> You are making noise. Bad boy. >>> Didn't you learn in kindergarten not to shout da-da-da ? >>> >> >>" The velocity of the source (star) has no effect on the direction in >> which we see the star, it is utterly irrelevant." -- da-da-da Andersen >> >>" If two observers are observing the same source, the aberration >> - that is the difference between the directions in which they >> see the source - depend _only_ on their relative speed." .-- da-da-da >>Andersen >> >> >>In the frame of the telescope the star moves, which is what is observed >>even in the far north of Norway where the Sun goes around the horizon >>without setting, da-da-da Tusseladd. It's only 600 miles for you to get >>to the Arctic circle, da-da-da Tusseladd. Di you know the Sun is a star, >>Tusseladd? >> >>Gehan don't see any difference between a moving source and a moving >>telescope, ie they are moving relatively to each other. Both Galilean >>Relativity and SRT agree on this. Poor confused da-da-da Tusseladd >>does not accept the PoR. > > ....but he can bend light poles by dropping an object down the middle and > driving past in his car. > Pitiful, really. It's no wonder the Vikings never got any further than Greenland, and even that they called "green" (even though it's still all glaciers) to attract settlers. They navigate by the sunstone, y'know, while the rest of the Europeans used a magnetic compass. http://www.nordskip.com/vikingcompass.html He's probably still using feldspar for street light poles, not that it matters when he's only 600 miles from the Arctic Circle and littered with McDonald's restaurants if "street view" is any true representation. I can bend light poles by hitting them with my car, but I prefer not to.
From: Inertial on 29 Mar 2010 19:09 "Paul B. Andersen" <paul.b.andersen(a)somewhere.no> wrote in message news:hoq7db$14db$1(a)news01.tp.hist.no... > On 20.03.2010 01:04, Inertial wrote: >> If light were simple ballistic particles, then if it was coming >> from a moving (or stationary)source aimed at a stationary telescope, >> then slowing it down would *not* change its angle. >> >> . <S> >> . >> . o >> . >> . >> . / / >> . >> . / / >> . >> . / / >> >> . <S> >> . >> . >> . >> . o >> . >> . / / >> . >> . / / >> . >> . / / >> >> . <S> >> . >> . >> . >> . >> . >> . /o/ >> . >> . / / >> . >> . / / >> >> . <S> >> . >> . >> . >> . >> . >> . / / >> . >> . /o/ >> . >> . / / >> >> . <S> >> . >> . >> . >> . >> . >> . / / >> . >> . / / >> . >> . /o/ >> >> >> If light were simple ballistic particles, then if it was coming >> from a stationary source aimed at a moving telescope, >> then slowing it down *would* change its angle. >> >> . <S> >> . >> . o >> . >> . >> . / / >> . >> . / / >> . >> . / / >> >> . <S> >> . >> . >> . >> . o >> . >> . / / >> . >> . / / >> . >> . / / >> >> . <S> >> . >> . >> . >> . >> . >> . /o/ >> . >> . / / >> . >> . / / >> >> . <S> >> . >> . >> . >> . >> . >> . / / >> . o >> . / / >> . >> . / / >> >> . <S> >> . >> . >> . >> . >> . >> . / / >> . >> . o / >> . >> . / / >> >> . <S> >> . >> . >> . >> . >> . >> . / / >> . >> . / / >> . o >> . / / >> >> . <S> >> . >> . >> . >> . >> . >> . / / >> . >> . / / >> . >> . o/ / > > Hm. > This is correct as it stands, but it rests on an assumption > you may not be aware of. > > Not to nit-pick, but I asked myself these questions: > > What is the difference between the inertial "rest frame", > and the inertial "moving telescope frame"? > > Why is the trajectory of the particle straight in the former > but bent in the latter? > > Let me illustrate. > In inertial frame A, a particle is going 'straight down', > and is reducing its speed from v1 to v2. > > o > o v1 > o > X > o > o v2 > o > The trajectory is a straight line in frame A. > > Frame B is moving 'horizontally' to the right at some speed v. > In this frame the trajectory would look something like this this: > > o > o > o > X > o > o > o Yes .. hence the change in angle. It all depends on in which frame the 'slowing' happens. > The trajectory is bent in frame B. > > Why? > The point is that there is no such thing as 'reducing the speed > of the particle along its direction of motion', because the direction > of motion is frame dependent. > So the important question is: > What is the direction of the force that is acting on the particle? > In frame A this force must be acting upwards opposite to the velocity > of the particle. > In frame B the force will still act vertically upwards, so it has an > angle to the velocity of the particle, and will change the direction > of the velocity as well as reducing the speed. > > The point is that if the speed of the particle is reduced by > entering some medium, like a water filled telescope, the speed reducing > force will act opposite to the velocity _in the telescope frame_, > so the trajectory of the particle will be straight _in the telescope > frame_. It really depends how the slowing happens, I guess. Does moving water take light along with it? > Your somewhat questionable assumption was that the speed reducing > force was acting opposite to the velocity of the particle in > the (arbitrary?) 'rest frame', and thus not in the 'moving telescope > frame'. I guess we should ask (if they were still alive) those who did the water-in-the-telescope experiments why they were expecting to possibly see a change in the angle :):) > The speed of the source is in any case utterly irrelevant. Yeup.
From: train on 29 Mar 2010 21:10
On Mar 30, 4:09 am, "Inertial" <relativ...(a)rest.com> wrote: > "Paul B. Andersen" <paul.b.ander...(a)somewhere.no> wrote in messagenews:hoq7db$14db$1(a)news01.tp.hist.no... > > > > > > > On 20.03.2010 01:04, Inertial wrote: > >> If light were simple ballistic particles, then if it was coming > >> from a moving (or stationary)source aimed at a stationary telescope, > >> then slowing it down would *not* change its angle. > > >> . <S> > >> . > >> . o > >> . > >> . > >> . / / > >> . > >> . / / > >> . > >> . / / > > >> . <S> > >> . > >> . > >> . > >> . o > >> . > >> . / / > >> . > >> . / / > >> . > >> . / / > > >> . <S> > >> . > >> . > >> . > >> . > >> . > >> . /o/ > >> . > >> . / / > >> . > >> . / / > > >> . <S> > >> . > >> . > >> . > >> . > >> . > >> . / / > >> . > >> . /o/ > >> . > >> . / / > > >> . <S> > >> . > >> . > >> . > >> . > >> . > >> . / / > >> . > >> . / / > >> . > >> . /o/ > > >> If light were simple ballistic particles, then if it was coming > >> from a stationary source aimed at a moving telescope, > >> then slowing it down *would* change its angle. > > >> . <S> > >> . > >> . o > >> . > >> . > >> . / / > >> . > >> . / / > >> . > >> . / / > > >> . <S> > >> . > >> . > >> . > >> . o > >> . > >> . / / > >> . > >> . / / > >> . > >> . / / > > >> . <S> > >> . > >> . > >> . > >> . > >> . > >> . /o/ > >> . > >> . / / > >> . > >> . / / > > >> . <S> > >> . > >> . > >> . > >> . > >> . > >> . / / > >> . o > >> . / / > >> . > >> . / / > > >> . <S> > >> . > >> . > >> . > >> . > >> . > >> . / / > >> . > >> . o / > >> . > >> . / / > > >> . <S> > >> . > >> . > >> . > >> . > >> . > >> . / / > >> . > >> . / / > >> . o > >> . / / > > >> . <S> > >> . > >> . > >> . > >> . > >> . > >> . / / > >> . > >> . / / > >> . > >> . o/ / > > > Hm. > > This iscorrectas it stands, but it rests on an assumption > > you may not be aware of. > > > Not to nit-pick, but I asked myself these questions: > > > What is the difference between the inertial "rest frame", > > and the inertial "moving telescope frame"? > > > Why is the trajectory of the particle straight in the former > > but bent in the latter? > > > Let me illustrate. > > In inertial frame A, a particle is going 'straight down', > > and is reducing its speed from v1 to v2. > > > o > > o v1 > > o > > X > > o > > o v2 > > o > > The trajectory is a straight line in frame A. > > > Frame B is moving 'horizontally' to the right at some speed v. > > In this frame the trajectory would look something like this this: > > > o > > o > > o > > X > > o > > o > > o > > Yes .. hence the change in angle. It all depends on in which frame the > 'slowing' happens. > > > > > The trajectory is bent in frame B. > > > Why? > > The point is that there is no such thing as 'reducing the speed > > of the particle along its direction of motion', because the direction > > of motion is frame dependent. > > So the important question is: > > What is the direction of the force that is acting on the particle? > > In frame A this force must be acting upwards opposite to the velocity > > of the particle. > > In frame B the force will still act vertically upwards, so it has an > > angle to the velocity of the particle, and will change the direction > > of the velocity as well as reducing the speed. > > > The point is that if the speed of the particle is reduced by > > entering some medium, like a water filled telescope, the speed reducing > > force will act opposite to the velocity _in the telescope frame_, > > so the trajectory of the particle will be straight _in the telescope > > frame_. > > It really depends how the slowing happens, I guess. Does moving water take > light along with it? > > > Your somewhat questionable assumption was that the speed reducing > > force was acting opposite to the velocity of the particle in > > the (arbitrary?) 'rest frame', and thus not in the 'moving telescope > > frame'. > > I guess we should ask (if they were still alive) those who did the > water-in-the-telescope experiments why they were expecting to possibly see a > change in the angle :):) > > > The speed of the source is in any case utterly irrelevant. > > Yeup. It's like this forum - we view the source - Albert Einstein, and viewed through our own telescopes and our own assumptions we cannot all agree. You raise an important point that since AE is not alive we cannot really know what he thought? We are interpreting his theory into our own FoR - translating it using .. I don't know what. Is it all relative? Is there a different between photons going down the telecope tube if the source was moving and the source was at rest? A B | . | | . | | . | | . | | . | | . | | . | | . | | . | | . | | . | | . | | . | | . | | . | | . | In A: the source and telescope are in stationary wrt each other In B: the source is moving, but the telescope is angled so the photon goes straight down What is the physical difference between A and B? |