"Hubble Science"
"Gravitational Lensing: Nature's Boost"
As Hubble looks out into these fields of galaxies, we sometimes see clusters of
galaxies; these are galaxies that are held nearby each other by their mutual gravity.
These clusters are massive conglomerations. There's so much mass that they have an actual
observable impact on space-time itself. Einstein predicted that mass distorts space, but we didn't
realize we could actually see the effects of that. But with Hubble, we have been able to see
distortions in space around clusters of galaxies. The way we see that is when light
from a background galaxy travels through that cluster of galaxies or around it, due to this
gravitational lensing effect. The lensing also magnifies that background galaxy. So if we look
in some of these distorted arcs, we can see more detail than we would ever have been able to see
without gravitational lensing, nature's boost. So Hubble has been used in an unexpected way for us,
to look at nature's magnifying glasses, these gravitational lenses, and using those to tell
us about much more distant galaxies in detail we could never have seen without the lensing,
and also to tell us how dark matter is distributed in those clusters;
because it turns out that most of the mass that's distorting space and these clusters of galaxies
is made of this unseen dark matter, not the visible stars in the galaxies, and we can't
see the dark matter. But by seeing how this background light is distorted, we can kind of
map out where that dark matter is through this effect we call gravitational lensing. So we're
learning a lot about dark matter, this mystery of matter we don't really know what it is, but
we know where it is in these clusters because of this innovative use of the Hubble Space Telescope.
[ MUSIC ]