This happens only once in sixteen years
It will be so close to the black hole that the speed of it will reach almost 3% of the speed of light
I said to my wife ‘I have to tell you something — it's really there
ESOcast 173: First Confirmation of Einstein’s General Relativity Near Supermassive Black Hole
Since Einstein published his theory of general relativity in 1915
scientists have embarked on a hundred-year crusade to prove him right...or wrong.
In pursuit of this goal, ESO has been training its telescopes on a hidden monster
in the heart of the Milky Way for over a quarter of a century.
This cosmic colossus is a supermassive black hole, four million times the mass of the Sun
surrounded by a tightly-bound group of stars.
Now, after an epic 26-year observing campaign
the effects of Einstein’s general relativity have been clearly seen for the first time around this supermassive black hole.
However, astronomers aren’t only interested in finding out if Einstein was right.
They also want to use these measurements to test our most fundamental understanding of the Universe.
The whole theories about the formation of the Universe — how the Universe is evolving
are based on one philosophical and fundamental assumption, which is that the laws of physics
are valid everywhere in the Universe and at any time in the Universe.
While here on Earth we can only prove these laws of physics now and under certain circumstances.
So it’s very important in astronomy to also check that those laws of physics
are still valid where the gravitational fields are much stronger
Preparations for this breakthrough began in early 2018, when astronomers travelled to ESO’s Paranal observatory
to make measurements of one of the most extreme gravitational laboratories.
Well you see the centre of our Milky Way, where we suspect there is a black hole
has stars orbiting this central black hole.
And these stars are measurement objects, if you like. They test the gravity of the object.
There’s one star in particular which we’ve been following now — believe it or not — for 25 years.
This star, called S2, recently passed very close to the black hole at a speed greater than 25 million kilometres per hour.
Astronomers were ready and waiting to make the most of this unique opportunity
with ESO’s cutting-edge instruments.
In spring 2018, one of our best stars which flies around the black hole in the galactic centre
actually comes closest to the black hole and that is what we want to observe and that’s the event we want to follow.
Making these measurements pushed the power of ESO’s Very Large Telescope to the limits.
You need to get very sharp images, and the best way we can get sharp images is to make big telescopes
Even with the impressive size of the Very Large Telescope
the only way to precisely measure the path of S2’s high-speed trip around the supermassive black hole
took some innovative telescope teamwork.
We create a super telescope — in this case which is 130 metres in diameter.
Light from all four Unit Telescopes of the Very Large Telescope was combined by the GRAVITY instrument
giving astronomers the sensitivity they needed.
We have all four telescope working together.
This combines the light from all four telescopes and this is GRAVITY
It measures movement which is the equivalent of an astronaut on the Moon moving a flashlight by about 10 cm
GRAVITY worked with another two of ESO’s state-of-the art instruments to reveal an effect called gravitational redshift.
This is visible when light from the star is stretched to longer wavelengths
by the very strong gravitational field of the black hole.
For the discovery a combination of three instruments of ESO were used
NACO, SINFONI and GRAVITY, and all three of those are unique.
However, capturing the fine details of gravitational redshift was no easy task.
Uh. That was a long path. It was very, very difficult.
It’s a long story — very bumpy! Not always easy, but very challenging.
This is the first time that this deviation from the predictions of simpler Newtonian gravity
has been observed in the motion of a star around a supermassive black hole
and is the result of years of collaboration between ESO and other institutions.
This is one of the huge benefits of ESO, and the way ESO works
is that there is always a very strong collaboration between ESO and institutes in its member states
which is very unique in the world because it enables ESO and the ESO Members to undertake projects like GRAVITY.
Thanks to ESO’s international collaborations and instruments
astronomers were able to witness the spectacle of a star hurtling past a supermassive black hole
providing a perfect cosmic experiment to test our understanding of physics.
More than one hundred years after he published the paper setting out the equations of general relativity
Einstein has been proven right once more
in a more extreme laboratory than he could have possibly imagined!
Transcribed by ESO; Translated by —