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Gravity is the eerie, mysterious glue that holds the universe together, but that’s not the end of its charm. We can also take advantage of the way in which space-time is deformed to see distant objects that would be very difficult to detect.
It’s called a gravitational lens, and it’s an effect predicted by Einstein, and it’s beautifully illustrated in a new edition of the Hubble Space Telescope.
In the center of the image (below) is an almost perfect glowing ring with what appears to be four interconnected light dots along its length, wrapping around two more dots with a golden glow.
(ESA / Hubble & NASA, T. Treu; Diabetes: J. Schmidt)
This is called Einstein’s Ring, and these bright spots are not six galaxies, but three: two in the middle of the ring and a quasar behind, their light distorted and amplified as it passes through the gravitational field in the foreground. Galaxies.
Since the masses of the two foreground galaxies are very high, this causes the space-time gravitational curvature around the pair. Any light that then passes through this space-time follows this curvature and enters our telescopes warped and warped – but also magnified.
Gravitational lens diagram. (NASA, ESA and L. Sidewalk)
It turns out to be a really useful tool for probing both far and near expanses of the universe. Anything that has sufficient mass can act as a gravitational lens. It could mean one or two galaxies, as we see here, or even massive galaxy clusters, which produce a wonderful mess of light trails from a lot of things behind them.
Astronomers examining deep space can reconstruct these scans and repeat the images to see more precise details of distant galaxies with a lens. But that’s not all gravitational lenses can do. The strength of the lens depends on the curvature of the gravitational field, which is directly related to the mass around which it is curved.
So the gravitational lens can allow us to weigh galaxies and clusters of galaxies, which in turn can help us find and map dark matter – the mysterious and invisible source of mass that generates additional gravity that cannot not be explained by things in the universe. It may already be detected.
https://www.youtube.com/watch؟v=PzSYbAKQheE
A little closer to home, a gravitational lens – or microlens, more precisely – could help us find objects in the Milky Way that are too dark for us to see otherwise, like stellar-mass black holes.
and gets smaller. Astronomers have been able to detect rogue exoplanets – those that are not associated with a host star, that roam the galaxy, cold and lonely – thanks to the magnification that occurs when these exoplanets pass between us and distant stars. They even used microgravity to detect exoplanets in other galaxies.
It’s pretty wild what the universe has in its own gravitational arms.
You can download a paper version of the above image from the ESA website.
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