What is a black hole? Do they really exist? How do they form? How are they related to stars? What would happen if you fell into one? How do you see a black hole if they emit no light? What’s the difference between a black hole and a really dark star? Could a particle accelerator create a black hole? Can a black hole also be a worm hole or a time machine? In Astro 101: Black Holes, you will explore the concepts behind black holes. Using the theme of black holes, you will learn the basic ideas of astronomy, relativity, and quantum physics. After completing this course, you will be able to: • Describe the essential properties of black holes. • Explain recent black hole research using plain language and appropriate analogies. • Compare black holes in popular culture to modern physics to distinguish science fact from science fiction. • Describe the application of fundamental physical concepts including gravity, special and general relativity, and quantum mechanics to reported scientific observations. • Recognize different types of stars and distinguish which stars can potentially become black holes. • Differentiate types of black holes and classify each type as observed or theoretical. • Characterize formation theories associated with each type of black hole. • Identify different ways of detecting black holes, and appropriate technologies associated with each detection method. • Summarize the puzzles facing black hole researchers in modern science.
01.02 – Black Holes in Pop Culture
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Del curso dictado por University of Alberta
Astro 101: Black Holes
123 calificaciones
De la lección
Introduction to Black Holes
Hello and welcome to the first module of Astro 101! In this module, you will become familiar with the basic structure of a black hole, learn the terminology used to describe them, and explore the history of black hole physics.
Conoce a los instructores
Sharon MorsinkAssociate Professor
Department of Physics, University of Alberta
Let's start our journey into the realm of pop culture with
a franchise that has been attracting fans for the last 50 years.
A generation of Star Trek enthusiasts grew up watching Star Trek The Original Series,
which first aired in 1966.
A lot has changed in the time since
Captain Kirk fought a gorn by hand in the original series.
Star Trek isn't merely science fiction but is
also known to challenge inequalities in society.
But Star Trek is known for singlehandedly inspiring a generation of scientists and
engineers whose work saw human exploration of
the moon and permanent laboratories in space.
My favorite Star Trek movie reboot of the franchise in 2009
with an epic space adventure with the tagline, the future begins.
The story begins following James Kirk's exploits as
a cadet in Starfleet Academy but an attack on
the Vulcan homeworld forces the cadets to become
crew of the newly commissioned USS Enterprise.
Without spoiling too much of the movie,
the writers of the film employed a strange form of fictional matter called red matter,
which appears to create black holes that can consume entire planets.
In the movie, the Vulcan homeworld has been attacked,
and the planet's surface collapses inwards.
Although visually impressive, Star Trek gets a lot of the black hole physics wrong.
For one, the audience is meant to understand that red matter black holes are traversable.
Unfortunately, traversable wormholes are merely a theory and would require
a super advanced civilization and a number of
notable scientific discoveries to permit travel.
In fact, travel through a wormhole, if possible,
would likely expose travelers to a serious dose of radiation,
making the journey fatal to squishy humans like me.
On the other hand, Star Trek explores some very interesting physics of black holes,
specifically how a spacecraft might escape if
it becomes trapped within the gravitational pull of a black hole.
In one scene, the enterprise is at maximum thrust
and is still being accelerated towards the black hole.
In order to save the crew,
the chief engineer Scotty suggests that the last option is to eject
the warp core and ride the shockwave from the explosion to safety.
At best, it explores interesting science fiction concepts.
At its worst, it makes some small,
maybe forgivable errors, in scientific judgment for the sake of entertainment.
I enjoy watching Star Trek and Doctor Who,
but often the treatment of science in these shows
doesn't satisfy my sense of scientific consistency.
One movie that did satisfy me was the 2014 movie Interstellar,
which presents the science of black holes as accurately as possible.
There is still black hole physics that is unknown,
like what happens when you cross an event horizon?
So, the movie makers do engage in
some speculation about what happens inside a black hole.
The black hole in Interstellar is a supermassive black hole named Gargantua.
Two planets are in orbit around the black hole at a safe distance,
which is a reasonable possibility even though in the TV show Doctor Who,
they claim that planets orbiting black holes are impossible.
It is important to the plot of Interstellar that Gargantua is a supermassive black hole,
since the strength of the tidal forces that could spaghettify
an astronaut is weaker for more massive black holes.
Although Gargantua causes enormous tides on Miller's planet,
the planet that orbits closest to Gargantua,
the tidal forces aren't strong enough to
destroy the planet or the characters on the surface.
Another cool bit of science that Interstellar gets right are
the extreme time differences between
Miller's planet and the spaceship that orbits farther away from the black hole.
When one hour passes on the planet,
seven years pass for the astronauts far from the black hole.
For me, the most exciting part of the movie is the view of
the black hole and the disk of material flowing around it.
This view of the black hole incorporates most of the science of
how light travels on curved paths around regions with gargantuan gravity.
The black hole Gargantua is extremely far away from us,
but luckily the writers included a wormhole that allows
a quick shortcut through space between Saturn and Gargantua.
Black holes exist but wormholes probably don't so this part is science fiction.
In the movie, they speculate that the wormhole was constructed by aliens.
I don't know how to construct a wormhole but then I'm not an alien.
I won't spoil the ending of the movie for you.
However, I'll just let you know that there is a trip into the black hole.
What happens when they enter the event horizon is pure speculation, but who knows?
Maybe the screenwriters are correct.
In 1977, George Lucas presented his creation Star Wars:
A New Hope to the world.
It was packed with brand new special effects like
fast-paced space battles and spectacular lightsaber duels.
Sadly, Star Wars didn't include anything that we would really consider a black hole,
unless you include the insatiably hungry Sarlacc.
So, we don't have much material from the Star Wars universe.
Fortunately though, Disney was aware of the success of Star Wars and in
1979 decided to fund their own space opera called The Black Hole.
The Black Hole was the biggest production in
Disney's history with $20 million spent on the budget,
allowing them to create incredible visual effects.
In the movie, the crew of the spacecraft
Palomino approaches a black hole on a scientific mission,
only to discover another ship in orbit around it,
the Cygnus, a long lost vessel.
The crew of the Palomino must assess the dangers around
the black hole and decide whether or not to mount a rescue mission.
Disney's The Black Hole was one of the first works of modern film making
that attempted to recreate the environment around a black hole.
Since we still don't have pictures of black holes,
the filmmakers relied on scientists of the day to tell them what it might look like.
Have a look at this scene from the bridge of the Cygnus,
a stark starry background is punctuated with a tear in the fabric of spacetime.
At the end of the 1970's,
this was the picture of a black hole.
In order to make such a convincing picture,
the filmmakers relied on 20 years of work from scientists,
like Roy Kerr, Roger Penrose,
Werner Israel and Stephen Hawking,
whose names come up a lot in this course.
They had been working on models of how black holes
behave and just what they might look like.
In addition, the nearby black hole Cygnus X-1,
which had then only been recently confirmed,
became the namesake of this ship in the movie
The Black Hole did a lot of things correctly that other movies failed to do,
like an accurate representation of an accretion disk for the time,
and accounting for the time dilation effects around the black hole.
However, in the film,
the crew of the Palomino descend past the event horizon,
where their interpretation of the interior is almost certainly false.
Instead of space-bending physics,
as the Cygnus descends into the black hole,
it becomes a fiery realm like a portrayal of Dante's Inferno.
In reality, crossing the event horizon has dozens of
dangers that would likely harm human explorers.
A lot has changed in the 40 years since Disney released
The Black Hole, especially related to black hole physics.
We now know the strength of gravitational waves produced by merging black holes,
and scientists are still developing theories to explain
what the interiors of black holes might look like.
This film introduces some of the interesting ideas about falling into a black hole,
but there is one thing that I can tell you that none of these movies can.
No one can tell you for certain what happens when you cross a black hole's event horizon.
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