Dan Coe tells of ghostly dark matter ring
Astronomers have seen more evidence of what they call ‘dark matter.’
It’s in a massive ghostly ring 5 billion light-years away.
Dan Coe: Dark matter is ghostly because it’s everywhere in our universe. It’s all around us. But we can’t see it and we can’t feel it. In fact, right now there might be a billion dark matter particles passing through your body every second.
That’s Dan Coe of Johns Hopkins University. He said astronomers infer the existence of dark matter by its gravitational pull on stars and galaxies. Coe was part of an international team of astronomers that used images from the Hubble Space Telescope.
They employed a technique called gravitational lensing, an effect predicted by Einstein’s General Theory of Relativity. I’s where light from far-away galaxies is slightly distorted by the gravitational pull of intervening dark matter.
Dan Coe: Observing gravitational lensing is like looking at pebbles on the bottom of a pond with ripples on the surface distorting the shapes of the pebbles we see.
Coe said the ring of dark matter his team found could be the result of a head-on collision between two clusters of galaxies. This work offers support in favor of the existence of dark matter.
But others have offered another possible explanation. It could be that Einstein’s theory of gravity breaks down at large scales. In that case, astronomers would need to re-formulate it.
Our thanks to:
Dr. Dan Coe
Johns Hopkins University