Lensed galaxies

Nov 12, 2010
A false-color image of a galaxy in the distant universe as seen by the Submillimeter Array (SMA). The four knots in the image are all the same galaxy; it appears multiple and distorted because of an intervening galaxy (not visible to the SMA) that magnifies and deforms it. Credit: M. Negrello et al.

In 1915, Einstein amazed the world by predicting that the path of light could be bent by mass. As a consequence, light from a distant galaxy passing by an intervening galaxy en route to earth will be distorted. Just as a glass lens can deform the appearance of objects seen through it, so can the mass of the intervening galaxy can act as a "gravitational lens," distorting the image we would otherwise see into a more complex shape.

It was not until 1979 that astronomers spotted the first gravitationally lensed galaxy, and since then several dozen lensed have been found. Such discoveries are difficult to make, however, because the lensed galaxies are far away, very faint, and randomly found across the sky, while there are many millions of other galaxies that at first glance appear similar.

The Space Observatory, launched in May 2009, has a powerful new camera designed to image the heavens at very long infrared wavelengths; galaxies undergoing bursts of star formation appear bright at these wavelengths because their young stars heat dust which then radiates in the infrared. When Herschel scientists analyzed the first images from the new camera, they discovered many new galaxies -- and a handful of outstanding, bright ones.

A not only distorts the image of a distant object, it can also act like an optical lens, collecting and refocusing the light to make it appear brighter. Wondering if might be responsible for the unusual brightness of these objects, the Herschel scientists teamed up with CfA astronomers Mark Gurwell and Ray Blundell to use the Submillimeter Array (SMA) to help resolve the question through its superb spatial resolution.

The SMA found that indeed the bright objects were distorted images of distant galaxies. Optical follow-ups helped to solidify the conclusion. In the most distant example, the far galaxy's light has been traveling towards us for about 10.8 billion years, about 80% of the age of the universe; light from the galaxy doing the lensing has been en route for a mere 2.8 billion years. These new results are significant because they confirm a reliable new method for finding these dramatic cosmic phenomena, but also because the warm dust they reveal helps probe the mechanisms of in the distant universe.

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User comments : 11

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VK1
1.4 / 5 (25) Nov 12, 2010
Einstein never said that light could be bent, he said space-time contorts, bends around massive objects, light just follows the curvature of space-time giving the illusion that it is bending. In his view it is the interstellar medium (space-time fabric) that bends.

This theory is outdated though.
Slotin
1 / 5 (24) Nov 12, 2010
This theory is outdated though.
It's just one of many particular views (a multiverses) of the real situation. For observer falling into black hole the light spreads with constant speed even when it circulates black hole at place together with observer, because his time and space-measured are deformed accordingly to path of light.

From observer outside of this field the path of light is curved instead, because his time/space measures aren't affected with remote gravity field. Both perspectives are perfectly relevant, but they lead to quite different outcome.

http://www.newsci...zon.html

The first perspective corresponds the general relativity, the second one corresponds the quantum mechanics.
Slotin
1 / 5 (23) Nov 12, 2010
Note that the gravitational lensing is actually a quantum mechanics phenomena, as it leads into (local) splitting of time arrow and causality (you can see many images of the same object at different places). To prove, it's relativity phenomena, you should measure space-time deform with clock inside of gravitational lens. But if you would visit such lens with clock, the lensing would dissapear for you inside of it!

It means, the gravitational lensing and general relativity are mutually contradicting each other, despite the relativity was used for lensing prediction originally. You can observe only time shift (Shapiro delay) and/or gravitational red shift outside of gravity lenses.

Einstein would be probably surprised, if he would realize, the experimental confirmation of general relativity with relativistic aberration has been actually based on quantum mechanics phenomena, which he fought against during his life.
theon
3 / 5 (4) Nov 12, 2010
Note that the gravitational lensing is actually a quantum mechanics phenomena,


This is not true. I have a glass ball, and I see the same type of lensing when I hold a pencil behind it. Gravitational lenses do just what your own lenses do: they bend the light.
KwasniczJ
1 / 5 (22) Nov 13, 2010
Gravitational lenses do just what your own lenses do: they bend the light.
In relativity the light has always invariant speed with respect to observer, so it cannot bend its path. It can only change it's wavelength. If general relativity would be valid, our Universe would appear empty and completely flat.
HGeo
1 / 5 (4) Nov 13, 2010
Could this give an explanation to the expansion of the Universe (which would then be an optical illusion...)
dgreyz
3.7 / 5 (3) Nov 13, 2010
This is not true. I have a glass ball, and I see the same type of lensing when I hold a pencil behind it. Gravitational lenses do just what your own lenses do: they bend the light.


That's refraction you're talking about, I consider that different from 'real' bending of light like this.
genastropsychicallst
1 / 5 (8) Nov 13, 2010
If science proofs be quadrate practum as common E spatial then evidence is a point of M fiction, means no real theory special C stripe.
frajo
5 / 5 (4) Nov 13, 2010
At least six out of eight comments are from Zephyr. Happy monologing.
HGeo
1 / 5 (1) Nov 13, 2010
I,HGeo,am not from Zephyr
Vendicar_Decarian
5 / 5 (1) Nov 14, 2010
"This is not true. I have a glass ball..." - Whomever

The passage of light through space is a process of diffusion as the photon moves from scatter to scatter off of the virtual particles that constitute the void, and limit it's speed to c.

Since there is more space near a gravitating object at distances farther away, the probability of a photon scattering into the closer regions surrounding a gravitating object is greater. The path of the photon therefore appears to curve around the gravitating object.

The bending of light is certainly a quntum mechanical effect.

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