The Event Horizon Telescope (EHT) project aims to capture the first image of a black hole's event horizon, providing a crucial test of Einstein's theory of gravity in an extreme cosmic environment.
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just over 100 years ago Einstein showed
how gravity could be imagined as a
distortion of space-time his equations
revealed that an object small enough and
massive enough could hide behind an
event horizon a point where gravity is
so strong that not even light could
escape astronomers now believe that
these objects known as black holes exist
they inhabit the Centers of almost all
galaxies where they can grow to be
millions or billions of times the mass
of our Sun despite this history and
growing astronomical evidence we have
never actually seen a black hole the
event horizon telescope or EHT is the
first experiment designed to capture a
black holes image in doing so the EHT
will test Feinstein's theory of gravity
at one of the most extreme places in the
universe the event horizon the best
chance we have of taking a picture of an
event horizon is the supermassive black
hole at the center of our own Milky Way
though it is 4 million times as massive
as our Sun it is so far away that
mapping its event horizon is equivalent
to standing in New York and counting the
individual dimples on a golf ball in Los
Angeles gas falling towards this black
hole heats up to billions of degrees
causing the event horizon to appear as a
silhouette whose size and shape are
predicted by Einstein's theory it is
best to observe this silhouette in light
with the wavelength of about one millimeter
millimeter
where the gas glows most brightly and
light can travel unimpeded from the
center of the galaxy to telescopes on
earth close to the black hole the light
waves appear circular like ripples in a
pond but by the time they reach Earth
they are essentially plane waves imaging
a black hole at this wavelength requires
a telescope as big as our planet the EHT
uses a global network of dishes to
simulate a telescope of this size each
dish collects and records radio waves
coming from near the black hole the data
are then combined to create the image of
the event horizon this will only work
however if the dishes are completely
synchronized to understand this let's
use the analogy of a
such as an optical telescopes used for stargazing
stargazing
imagine the EHT formed from all the
different array sites as one big
parabolic mirror the mirror is curved so
that when a line of waves comes into the
dish they bounce off at specific angles
and arrive at the focus at the same time
when the EHT sites are synchronized
their recordings can later be perfectly
aligned in the same way that the mirror
aligns the optical light
if the surface of the mirror is not
stable if it is vibrating for example
the reflected light rays will not
combine properly at the focus for the
EHT an unstable mirror surface is
analogous to an unstable recording to
ensure stability the EHT uses atomic
clocks that will lose only one second
every hundred million years the amount
of data recorded during observations is
so large that it could never be
transferred over the internet instead
the recordings are stored on hard disks
and shipped back to a central facility
for processing there a supercomputer
combines the data from all the sites
staggering them during playback to
account for the time difference between
waves getting to each telescope the
resulting data can then be used to make
images with extreme magnifying power as
more dishes join the HT and the more
widely spaced they are the sharper our
image of the event horizon will be in
April 2017 the HT coordinated
observations of the Milky Way's central
black hole using a global network of
telescopes an international team of
astronomers is analyzing the data eager
to bring a black hole into focus for the
first time the results could transform
our understanding of black holes gravity
and even the universe [Music]
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