Gravity is the strange and mysterious glue that binds the universe together, but this is not the limit of its charms. We can also take advantage of the way space-time deforms to see distant objects that would otherwise be much more difficult to distinguish.
This is called the gravitational lens, an effect predicted by Einstein, and is very well illustrated in a new version of the Hubble Space Telescope.
In the center of the image (below) is a shiny, almost perfect ring with what appear to be four bright spots threaded along it, surrounding about two more dots with a golden sheen.
(ESA / Hubble and NASA, T. Treu; Recognition: J. Schmidt)
This is called the Einstein ring, and these bright spots are not six galaxies, but three: the two in the middle of the ring and a quasar behind, their light distorted and amplified as it passes through the gravitational field of the two. close-ups. galaxies.
Because the mass of the two galaxies in the foreground is so high, this causes a gravitational curvature of space-time around the pair. Any light that passes through this space-time follows this curvature and enters our greased and distorted, but also enlarged telescopes.
Illustration of the gravitational lens. (NASA, ESA and L. Road)
This, it turns out, is a really useful tool for exploring both the extremes and the near ends of the Universe. Anything with enough mass can act as a gravitational lens. This can mean one or two galaxies, as we see here, or even huge clusters of galaxies, which produce a wonderful mess of light spots from the numerous objects behind them.
Astronomers observed in deep space can reconstruct these spots and replicated images to see far more distant galaxies in this way. But that’s not all the gravitational lens can do. The strength of a lens depends on the curvature of the gravitational field, which is directly related to the mass being curved around it.
Thus, gravitational lenses can allow us to weigh galaxies and galaxy clusters, which in turn can help us find and map dark matter: the mysterious invisible source of mass that generates additional gravity that cannot be explained by things. of the Universe. it can actually detect.
A little closer to home, the gravitational lens (or microlensification, to be more precise) can help us find objects inside the Milky Way that would be too dark to see otherwise, such as black holes with too much star. · Lar.
And it gets smaller. Astronomers have been able to detect rogue exoplanets — those that are not attached to a host star, which roam the galaxy, cold and sunny — of the increase that occurs when these exoplanets pass between us and distant stars. And they have even used gravitational microlensation to detect exoplanets in other galaxies.
It’s pretty wild what the Universe has in its gravitational sleeves.
You can download a version of the wallpaper from the image above on the ESA website.