A supernova has exploded in a galaxy not unlike our own. The photons unleashed will travel for billions of years through vacuum, dust and Earth’s atmosphere before being focused on to a telescope. From faint specks in blurred pictures, astronomers will use that supernova and many others to gauge the strength of dark energy, the mysterious force stretching our universe apart.
Only this isn’t our universe. It’s a giant fake – a simulation with a known amount of dark energy plugged in at the beginning. As if checking their answers against the ones in the back of the book, researchers compare the programmed strength of dark energy against that measured from the mocked-up images the virtual telescopes create. The difference between the two will let astronomers refine their real-world methods and help the hunt for dark energy in the real universe.
The telescope that will benefit from this cosmic charade is the Large Synoptic Survey Telescope (LSST), which will look for dark energy and more for real atop a Chilean mountain from 2022. But such experiments are finding uses in all areas of astronomy.
“I would describe them as test universes,” says Rachel Mandelbaum of Carnegie Mellon University in Pennsylvania. “We can test that our analysis algorithms are able to remove all the junk we don’t care about.”
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