Earthsky Interviews
Dan Coe tells of ghostly dark matter ring
12-06-2007 - Space
See a hi-res version of this image.
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
If the dark matter has mass (since it’s creating gravitational lensing) then, if there were billions of particles of it passing through us, wouldn’t we be able to measure the change by weighing?
Gostly?
Since darkness is the absence of light , and determine to be allusionary how can it be actively posible for such activity as described dark Matter passing through physical forms.Or did you mean this is a Intellengence that is active in life forms such as humans wihout thier koowledage, Could this be the cuase of diseases or condtions such as seizure disorders , unprovoked violence random killings , child abuse ,Genocide ?
“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”
If I remember from my physics classes right light takes longer to get from point A to point B in water because it isn’t following a straight path. Now if dark matter has a similar effect on light and the light from start is billions of light years away could we be off by thousand maybe millions of years because dark matter is bending the light?
I really have to wonder what passes for proof among astronomers today. Despite zero real proof of its existence they eagerly jump on this concept of dark matter. It seems much more likely that we don’t understand gravity as well as we would like to believe. The problem is that we have no way to verify the answers so these high priests of astrophysics can claim whatever they want. Even when their answers are contradictory and nonsensical, who can dispute them?
WHAT!!!!!!yourcrazy
A lot of good comments so far! First of all, I think Jim is right, we should all be very skeptical about Dark Matter. Just as Einstein rewrote Newton’s law of gravity, we may just need the next Einstein to come along and rewrite the law of gravity again. Recent observations like the Bullet Cluster and this Dark Matter ring are hard to explain with alternative theories of gravity; Dark Matter explains them much more naturally. But until we actually detect and produce Dark Matter particles in the lab, it will be very difficult to rule out alternative theories and prove convincingly that Dark Matter exists.
Of course detecting Dark Mater particles is hard to do, since these particles (if they exist) interact so rarely with ordinary matter, with perhaps a billion particles passing through each of our bodies every second. Similarly, billions — even hundreds of billions — of neutrinos are also passing through your body every second. And that we’re more sure about, since we’ve actually detected many neutrinos! The neutrino also has a small amount of mass. But since they (almost always) pass right through us, we don’t usually get a chance to weigh them. The same goes for Dark Matter.
In those rare instances when Dark Matter particles do interact with our bodies, could they cause us to behave erratically? I doubt it, although cosmic rays are believed to cause cancer sometimes…
Finally, in response to Chris’s question, Dark Matter (and ordinary matter, for that matter) bends space, according to Einstein. Light then follows that curvature in space. This behavior is very similar to light passing through a glass lens or being refracted by water, as you say. But the extra distance that light rays travel due to gravitational lensing only takes an extra month or so in this case. In other cases of gravitational lensing, such time delays have actually been measured and are generally explained well by our theories.
By the way, that quote about looking at pebbles was actually me quoting James who may have been quoting someone else before him…
If you have any more questions / comments, I’ll be checking back on this webpage here. You can also feel free to e-mail me at coe(at)caltech.edu. And if you’d like to read more about this Dark Matter ring, an extended transcript of my interview with Aitana is available at my website http://www.its.caltech.edu/~coe/DMring
We dontunderstand gravity. It is a theory just like electricity is. There is no real proof of it.
Just a thought: could this “gravitational ring” be caused by a black hole with no event horizon?