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before my theory, it had always been assumed that if all matter vanished from the universe, space and time would remain; according to relativity he said this was not true
It was not until 1979 that astronomers spotted the first gravitationally lensed galaxy, and since then several dozen lensed galaxies 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
A gravitational lens 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 gravitational lensing 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.
I was surprised to learn that Herschel is so good at finding these cosmic lenses," said Asantha Cooray of the University of California, Irvine. "Locating new lenses is an arduous task that involves slogging through tons of data. With Herschel, we can find a lot of them much more efficiently." Cooray is a co-author of a paper about the discovery, appearing in the Nov. 5 issue of the journal Science. The lead author is Mattia Negrello of the Open University in the United Kingdom.
A cosmic magnifying lens occurs when a massive galaxy or cluster of galaxies bends light from a more distant galaxy into a warped and magnified image. Sometimes, a galaxy is so warped that it appears as a ring -- an object known as an Einstein ring after Albert Einstein who first predicted the phenomenon, referred to as gravitational lensing. The effect is similar to what happens when you look through the bottom of a soda bottle or into a funhouse mirror.
The results showed that foreground galaxies were indeed magnifying all five of the bright galaxies. The galaxies are really far away -- they are being viewed at a time when the universe was only two to four billion years old, less than a third of its current age.
We've known for a long time that lensing is capable of making a physical measurement of Hubble's constant," KIPAC's Phil Marshall said. However, gravitational lensing had never before been used in such a precise way. This measurement provides an equally precise measurement of Hubble's constant as long-established tools such as observation of supernovae and the cosmic microwave background. "Gravitational lensing has come of age as a competitive tool in the astrophysicist's toolkit," Marshall said.
"With the new spectrograph we can see galaxy halos out to at least 150,000 parsecs," says Tripp. One kiloparsec is about 19 trillion miles. "Where once we saw only the framework we are now getting a more complete picture, including the composition and movement of gases in the envelope, varying temperatures in different locations and the chemical structure, all in incredible detail," Tripp adds.
Not only have we found that star-forming galaxies are pervasively surrounded by large halos of hot gas," says Tripp, "we have also observed that hot gas in transit. We have caught the stuff in the process of moving out of a galaxy and into intergalactic space."
On-going expansion of the universe is not a remnant of some furious bang at a distant past, but the universe is expanding because energy that is bound in matter is being combusted to freely propagating photons, most notably in stars and other powerful celestial mechanisms of energy transformation,” Annila said. “Thus, today’s rate of expansion depends on the energy density that is still confined in matter as well as on the efficacy of those present-day mechanisms that break matter to light. Likewise, the past rate of expansion depended on those mechanisms that existed then, just as the future rate will depend also on those mechanisms may emerge in the future. Since all natural processes tend to follow sigmoid curves when consuming free energy in the least time, also the universe is expected to expand in a sigmoid manner.”
Hubble directly observes the disc around a black hole
Until now, the minute apparent size of quasars has meant that most of our knowledge of their inner structure has been based on theoretical extrapolations, rather than direct observations.
The team therefore used an innovative method to study the quasar: using the stars in an intervening galaxy as a scanning microscope to probe features in the quasar's disc that would otherwise be far too small to see. As these stars move across the light from the quasar, gravitational effects amplify the light from different parts of the quasar, giving detailed colour information for a line that crosses through the accretion disc.
Originally posted by Iamschist
Thank you so much for this post. I understand much more than I did about gravitational lensing. It is no small feat that you are able to explain such a complex idea in terms a regular person can comprehend. S&F
Originally posted by Iamschist
reply to post by XPLodER
Whole new way to look at a black hole, somehow it does not look as menacing, why does it look like it has no center? Great photos.