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Author Topic:   Light + Gravity = Opticle Illusion
btseshasayee
Inactive Member


Message 1 of 14 (199130)
04-14-2005 1:59 AM


It is proposed and later proved during the recent observations during the Total Solar Eclipse that gravity bends the light rays.
Now, say two (or more) light rays eminating from a distant galaxy at different angles, are likely to converge to earth taking different routes, interacting with the gravity of the other objects on the way ( stars,galaxies,blackholes,dark matter etc.). So we may end up observing multiple images of the same galaxy, apparently situated on the different points on the sky.
So we may be actually counting/seeing more objects than the actual number present in the universe, due to this so called "kaleidoscope effect".
Please comment.

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AdminNosy
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From: Vancouver, BC, Canada
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Message 2 of 14 (199238)
04-14-2005 10:26 AM


Thread moved here from the Proposed New Topics forum.

  
contracycle
Inactive Member


Message 3 of 14 (199244)
04-14-2005 10:32 AM


Well, possibly I suppose, but I'm not sure the bending is that severe. It is not as if the light beam becomes curved from then on and follows an arc through space; it is bent inside the gravity well, and then exits in a straight line, as it entered.
But, this realisation makes for one of the collest potential science toys ever - a monstrous telescope. Basically we use the gravity well of our sun as a lens, and hang a receiver out by the orbit of Jupiter to form the image. That should give us glorious resolution, and we only have to build the receiver!

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Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 4 of 14 (199247)
04-14-2005 10:41 AM
Reply to: Message 3 by contracycle
04-14-2005 10:32 AM


Hopefully Eta will chime in with links to images, but this kaleidoscopic-like effect is well known. I can recall a picture of a galaxy behind which sits another galaxy, and the light from the obscured galaxy is bent as it passes the nearby galaxy, creating multiple images of the obscured galaxy in a ring around the nearer galaxy.
The name that I've seen applied to this effect is gravitational lens, because it can also result in magnification of distant objects.
--Percy

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jar
Member (Idle past 394 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 5 of 14 (199282)
04-14-2005 12:03 PM
Reply to: Message 1 by btseshasayee
04-14-2005 1:59 AM


One classic example of this is the Einstein Cross. You can find some information here. And here is an image of the Cross itself.

Aslan is not a Tame Lion

This message is a reply to:
 Message 1 by btseshasayee, posted 04-14-2005 1:59 AM btseshasayee has replied

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 Message 8 by btseshasayee, posted 04-14-2005 10:23 PM jar has not replied
 Message 9 by Gabe Webb, posted 04-15-2005 10:12 AM jar has replied
 Message 12 by btseshasayee, posted 04-17-2005 2:16 AM jar has not replied

  
btseshasayee
Inactive Member


Message 6 of 14 (199484)
04-14-2005 10:14 PM
Reply to: Message 4 by Percy
04-14-2005 10:41 AM


I intend to state the effects other than the Gravitational Lensing. Thanks for responding. I am also waiting for Eta's response/reaction.

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Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 7 of 14 (199486)
04-14-2005 10:19 PM
Reply to: Message 6 by btseshasayee
04-14-2005 10:14 PM


The image Jar provided is fine, I don't know if Eta will post anything.
--Percy

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btseshasayee
Inactive Member


Message 8 of 14 (199487)
04-14-2005 10:23 PM
Reply to: Message 5 by jar
04-14-2005 12:03 PM


I intend to state the effects other than Gravitational Lensing. Thankyou.

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 Message 5 by jar, posted 04-14-2005 12:03 PM jar has not replied

  
Gabe Webb
Inactive Member


Message 9 of 14 (199556)
04-15-2005 10:12 AM
Reply to: Message 5 by jar
04-14-2005 12:03 PM


That same 'Einstein Cross' can also form a ring if the light source is properly aligned on the opposite side of a black hole or other mega-gravity source.
Although I would assume that would need to be pretty precise to work...
Anyway I agree - a stellar telescope would be exceedingly cool, however the image would be reversed and shown in a polar form - because light from the source can be bent along either side of the star which functions as our 'lens', it would create a whole lot of confusion and double-images to work with.

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 Message 5 by jar, posted 04-14-2005 12:03 PM jar has replied

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jar
Member (Idle past 394 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 10 of 14 (199583)
04-15-2005 12:33 PM
Reply to: Message 9 by Gabe Webb
04-15-2005 10:12 AM


We already have a stellar telescope that's pretty accurate. When considering local land or space telescopes remember that by taking two shots at the same object 6 months apart you get the same effect as the if mirror was >180,000 miles across.

Aslan is not a Tame Lion

This message is a reply to:
 Message 9 by Gabe Webb, posted 04-15-2005 10:12 AM Gabe Webb has replied

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Gabe Webb
Inactive Member


Message 11 of 14 (199631)
04-15-2005 5:18 PM
Reply to: Message 10 by jar
04-15-2005 12:33 PM


...but taking two pictures from different vantage points is like your eyes: it might provide depth perception, but won't do diddly for the clarity of your vision.
What I meant by my previous statement was this:
Using the bending effect of gravity, more than one photon might travel to the viewer by the exact same vector. This would create a superimposition of one image onto another.
Not to mention the fact that the same photon might take three or four different paths around that gravity source, just at increasing and decreasing proximity to it, thus creating the same part of an image shown in more than one place, as well as maybe flipped or reversed or skewed, etc.
It would be a pretty confusticating way to look at faraway stuff. Not to mention the fact that things might get muddled up by the sun's corona. (Unless that is just a byproduct of our atmosphere. I really don't know.)
EDIT- as well as the fact that light approaching from the center of your image would be bent much more than light at the optimum focal point, making a ring of correct image, then getting brogressively blurrier as you go in or out.
I really wish I could attach a Paint image to illustrate my point, but this forum wouldn't let me attach stuff... grrr...
This message has been edited by Amadameus, 04-15-2005 04:20 PM

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btseshasayee
Inactive Member


Message 12 of 14 (199828)
04-17-2005 2:16 AM
Reply to: Message 5 by jar
04-14-2005 12:03 PM


Clarification
I understand that GL effect occurs when the light source,deflector and the observer are perfectly aligned. But my opening post is about deflector(s) not aligned with source and observer.Perhaps my choice of the word "converge" is misleading.
I would like you to read it as "reach" instead of "converge".
Now I would like to illustrate my point with an hypothetical example:
Imagine a rhombus (with its longer diagonal in verticle position). A light source is situated at top vertex and observer at the bottom. The two deflectors(say, of identical mass) are situated on the other two vertices.Now the light travelling along the vertical diagonal directly reaches the observer. Two other light rays travelling along the top two sides of the rhombus get diverted by the deflectors. Deflected light rays travel along the bottom sides and reach the observer. The result is 3 images (one real and two vertual) spacially well seperated. Ofcourse if only one deflector is imagined, under favourable conditions it will give rise to two images. Is it not a remote possibility?
This phenomenon can be called "Gravitational Mirror" effect rather than Gravitational lens, even though the cause of both effects is gravity.
Hope I could drive home my point (within my limitations).

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Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 13 of 14 (199859)
04-17-2005 9:12 AM
Reply to: Message 11 by Gabe Webb
04-15-2005 5:18 PM


Amadameus writes:
Not to mention the fact that the same photon might take three or four different paths around that gravity source, just at increasing and decreasing proximity to it, thus creating the same part of an image shown in more than one place, as well as maybe flipped or reversed or skewed, etc.
I think you mean light from the same part of the object, not the same photon. Multiple images of the same object is precisely what is happening in the image of Einstein's Cross that Jar provided.
It would be a pretty confusticating way to look at faraway stuff. Not to mention the fact that things might get muddled up by the sun's corona. (Unless that is just a byproduct of our atmosphere. I really don't know.)
The amount of bending by our own sun is so miniscule that it could not bend light to a focal point at a place as close to it as the earth.
--Percy

This message is a reply to:
 Message 11 by Gabe Webb, posted 04-15-2005 5:18 PM Gabe Webb has not replied

  
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 14 of 14 (199865)
04-17-2005 9:29 AM
Reply to: Message 12 by btseshasayee
04-17-2005 2:16 AM


Re: Clarification
Btseshasayee writes:
Imagine a rhombus (with its longer diagonal in verticle position). A light source is situated at top vertex and observer at the bottom. The two deflectors(say, of identical mass) are situated on the other two vertices.Now the light travelling along the vertical diagonal directly reaches the observer. Two other light rays travelling along the top two sides of the rhombus get diverted by the deflectors. Deflected light rays travel along the bottom sides and reach the observer. The result is 3 images (one real and two vertual) spacially well seperated. Ofcourse if only one deflector is imagined, under favourable conditions it will give rise to two images. Is it not a remote possibility?
I have only a vague recollection, so someone else will have to fill in the blanks, but I believe the original image and more than one ghost image of a distant object caused by the bending of light by closer objects has been observed.
The effect is caused by plain old general relativity and is nothing to be amazed at. Whether or not it's been observed, the specific situation you describe follows the laws of general relativity and so is possible. Whether we've actually observed it depends upon whether the universe has provided objects in the right positions from our perspective.
--Percy

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