We may have just gotten the first real picture of a black hole.
No not these artist impressions that you see all over the Internet, this is the real deal.
In this video, we will be talking about how we might have a picture of a black hole and
we’ll also talk about Kugelblitz’s and what they are.
The project is named the Event Horizon Telescope, or EHT for short, and is aiming to take the
first real image of a black hole.
They are looking at two supermassive black holes: the closest known black hole Sagittarius
A* and the even larger supermassive black hole in the centre of the galaxy M87, also
known as Messier 87 or Virgo A. M87 is a very large elliptical galaxy located 54 million
light years away from Earth.
Sagittarius A*, on the other hand, is located only 26,000 light years away in the centre
of the Milky Way and has the mass of about four million suns.
Being so far away and the fact that you can’t actually see black holes, how do we know it’s
there?
Well, since the start of this century, for over 16 years now, some astronomers have been
observing certain stars using infrared telescopes, in order to see past the dust.
They watched the movement of these stars and found that they seemed to have slingshot orbits
around something that wasn’t there.
The astronomers concluded that these stars were orbiting a black hole because that's
the only thing small and heavy enough to cause these stars to act like they do.
This black hole was of course named Sagittarius A*.
As mentioned, Sagittarius A* is located 26,000 light years away so, as you can imagine, it
is really difficult to take a picture of it.
Trying to take a picture of the black hole in the centre of the Milky way is as hard
as taking a picture of an orange on the moon, here from Earth.
The larger the telescope, the better the resolution and level of detail.
It turns out that we would need a telescope the size of Earth to take a picture of Sagittarius
A*.
But it’s impossible to construct a telescope the size of Earth.
So how on Earth have we managed to take a picture of these black holes?
Well, the Event Horizon Telescope isn’t just one telescope.
EHT actually consists of many telescopes scattered from all around the world.
Some of the locations where the telescopes are located are Chile, Hawaii, Arizona, Spain,
Mexico and there’s even a telescope involved that’s in the South Pole!
All the radio telescopes come together and work as one large global array.
And by using a technique called very-long-baseline interferometry, or VLBI, the Event Horizon
Telescope team point every telescope into one gigantic telescope.
This way we DO have a telescope the size of the Earth… just virtually.
This way, the Event Horizon Telescope actually could detect an orange on the moon, if oranges
were detectable in those wavelengths.
They’re aiming to see the black hole’s event horizon, the boundary where the gravitational
pull of the black hole becomes so strong that nothing can escape, not even light: the fastest
thing in the universe.
Stephen Hawking uses a good analogy for it.
He said “Falling through the event horizon, is a bit like going over Niagara Falls in
a canoe”, he said.
“If you are above the falls, you can get away if you paddle fast enough, but once you
are over the age, you are lost.
There's no way back".
This is why it's given the nickname "the point of no return”.
We'll hopefully see the shadow the black hole causes onto the bright matter zipping around
it.
When matter falls over the event horizon it lets out radiation which is why the rim of
the black hole is extremely bright.
We're hoping that we can detect this radio wave in order to get the first image of a
black hole.
Assuming that we do get a picture of a black hole, it may look similar to a solar eclipse
because of the way black holes bend light.
It will also test Einstein's theory of general relativity.
Based on Einstein's theory of general relativity, we're meant to see a crescent of light surrounding
a black blob.
So if we do get a picture of a black hole will it follow Einstein’s theory, that has
passed so many tests, or will it not?
As mentioned, the light is from matter, so dust and gas, just before the black hole swallows
it.
And we may learn how black holes produce massive jets.
Each observatory produced about 500 terabytes of data, which was stored into 1024 hard drives.
Each location, where each observatory is, hasn't got the equipment to process them,
so jets will fly them to Massachusetts, where the supercomputers will crunch the huge amount
of data.
Unfortunately the data from the South Pole can't be transported until the end of October,
meaning that it could be somewhere in the first quarter of 2018 when we see the results.
We’ve all heard of black holes, I’ve just been talking about how the Event Horizon Telescope
might get a picture of a black hole using VLBI, which I mentioned earlier as very-long-baseline
interferometry.
What you might have not heard of though is something called a kugelblitz.
A kugelblitz is a black hole formed entirely from light.
Before we talk about kugelblitz’s though let’s talk about black holes for a second.
We’ll come back to the kugelblitz in a second.
On the other hand, a black hole is an object with a gravitational field strength so strong
that nothing can escape, not even light, the fastest thing in the universe.
The concept of a black hole was first thought of in the 18th century by the geologist John
Mitchell.
In those days, black holes were not considered to be real; Einstein even assumed they didn’t
exist.
But then, later on, astronomers discovered observational evidence of black holes.
One of the latest evidence of black holes comes from the third detection of gravitational
waves, ripples in the fabric of spacetime.
In short, LIGO, Laser Interferometer Gravitational-Wave Observatory, detected gravitational waves
for the third official time, and doing so they found out loads of stuff, such as that
that the gravity waves were created when two black holes merged and that it happened three
billion years ago.
If you want to know more about that check out my video on it, after watching this one.
In the core of stars they are constantly fusing millions of tonnes of hydrogen into helium
every second, which releases gamma radiation.
Without doing this, stars wouldn’t be stable.
They’re held together by two opposing forces, the inward pull of gravity, and the outward
push of radiation.
So as long as the star is doing fusion in the core, it will stay stable.
There’s enough hydrogen to keep a star going for billions of years, the sun has been doing
it for about five billion years and will continue to do so for another five billion years, but
eventually, the star will run out of hydrogen to convert to helium, so it has to start using
the helium it has built up.
And for stars way more massive than our sun the heat and pressure at their core allows
them to continue the fusion process but with heavier elements, going through carbon, neon,
oxygen, silicon until they reach iron.
The fusion process to get iron doesn’t generate any energy.
Because of this, the perfect balance between gravity and the emitted radiation ends, with
gravity winning.
The core of the star collapses, causing a supernova.
After this the star will either become a neutron star or if the star is massive enough, the
core becomes a black hole.
To become a black hole, a star has to have about five solar masses.
In the process of becoming a black hole all of the star’s mass collapses down into a
smaller and smaller region of space until to escape the star you need to travel faster
than the speed of light, which is impossible.
Black holes forming at the end of a star’s life is the main way a black hole can form,
but there are other ways.
For instance black holes can also be created when two large and dense objects, such as
neutron stars, collide with each other.
And there are still mysteries about black holes.
We still don’t know for sure how the supermassive black holes such as Sagittarius A*, that seem
to be in every galaxies centre, formed.
Black holes have sparked other ideas as well.
White holes are black holes in reverse.
A white hole would be an object that spews out matter and matter would never be able
to enter it.
Go watch my video on white holes after this one, if you want to know more about that.
Back to the kugelblitz.
The word kugelblitz was given because it means “ball lightning” in German.
To make Earth into a black hole you would need to compress the six trillion trillion
kilograms of everything on Earth into a sphere with a diameter of just sixteen millimetres.
To make the same black hole that has the mass of Earth but this time, using light instead
of matter, how much light would we need?
Well it turns out to make a kugelblitz with the mass of Earth we would need all the light
that has been emitted from all the stars over the past 10 years within 350 light years of
Earth and put all of that into a space of about the size of a mosquito.
That’s a lot of light.
It seems impossible how that much light could fit in such a small section of space.
That’s not the only problem though.
With that much light energy in such as small space it would be extremely hot, as hot as
the universe was straight after the big bang, and stuff doesn’t really work at that point
in time.
So kugelblitz’s are theoretically possible, according to some of Einstein’s equations
but they still have many problems against them.
Comment down below whether you think kugelblitz’s will ever exist.
Personally I don’t see how the universe could possibly create one but they’re still
really cool concepts.
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Thank you so much for watching, I’ll see you later.