Caught in a Dark Web

The world that we see is just bright dew gleaming on a vast web of darkness. 

No, seriously, it is. 

A crew of astrophysicists at the Johns Hopkins University Space Telescope Science Institute used the Hubble Space Telescope to map the dark matter in a distant galaxy cluster by studying subtle gravity lensing effects on light from very distant objects. 

Gravity lensing, as every third-grader knows, is the effect on light from distant sources created by the gravity fields of massive objects.  Gravity can bend light, sometimes creating double images of distant quasars and galaxies.  By studying how the light gets bent, one can learn something about where the massive dark objects are.

When they got done crunching the numbers, the Hopkins team produced the inevitable three-dimensional computer-generated image which appears to show that the galaxy cluster is filled by a huge webwork of filaments of dark matter, with the bright matter (i.e. galaxies) gathered where the filaments meet.  It seems likely that the increased density of dark matter is what collects the bright matter.  Presumably this result holds for the rest of the universe as well. 

So what is dark matter anyway?  Nobody knows.  It's there, it has mass and thus affects us via gravity, but otherwise dark matter is like ghost-stuff.  You can't see it, you can't touch it, and apparently other dark matter can't touch it either.  Particles of dark matter pass through each other when they collide.  And something like 90 percent of everything that exists is dark matter.  Bright matter -- the stuff we're made of -- is just the icing on the cosmological cake. 

Yet it appears that the structure of the universe is determined by dark matter.  This vast, mysterious webwork of titanic filaments is what the universe "really" looks like.  The clumps of bright matter formed where the filaments come together are apparently just epiphenomena, cosmic by-products, like dust in the corner of a room. 

Comments

[Thom H.]

As if I wasn't feeling insignificant enough already. ;-)