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Big History Project
Course: Big History Project > Unit 2
Lesson 3: What Are Disciplines? | 2.2- ACTIVITY: Who Knows What?
- ACTIVITY: DQ Notebook 2.2
- WATCH: Ways of Knowing – Introduction to Cosmology
- WATCH: Ways of Knowing – Introduction to Astrophysics
- READ: Revealing the Dark – Vera Rubin – Graphic Biography
- ACTIVITY: What Do You Know? What Do You Ask?
- Quiz: What Are Disciplines?
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WATCH: Ways of Knowing – Introduction to Astrophysics
Astrophysics, a branch of physics, explores the universe's laws and phenomena using mathematics. It's a collaborative field involving theorists, experimentalists, and observers. Theorists, like Janna Levin, use math to make discoveries and predictions. Astrophysics tackles big questions like the universe's origins, its evolution, and its composition, including the mystery of dark matter and energy. Created by Big History Project.
Want to join the conversation?
- If the moon goes around the sun then what does the sun go round?(3 votes)
- The moon does not go around the sun directly, it circles around the earth (and the earth in turn circles the sun). The sun (and the rest of our solar system) is moving around the center of our Milky Way galaxy.(16 votes)
- Which of the physicist branches is the hardest, experiments, observations, or theory? I would guess theory...(5 votes)
- I wouldn't think any of them is any harder or easier in practice, but only related to the practitioner. I would think of them more as disciplines or methodologies for practicing. And it goes far beyond practicing physics or science, but really anything from farming to religion.(2 votes)
- Can u put more things about astrophysics because it is very interesting for me and I love info about the universe(3 votes)
- If you want to see more about the universe make sure to check out Khan Academy's cosmology and astronomy section! You can find it here: https://www.khanacademy.org/science/cosmology-and-astronomy(6 votes)
- Aren't theorists technically philosophers?(4 votes)
- Technically they're theorists but what they do can be very hypothetical and abstract like much of philosophy. There was a time when the word scientist didn't exist; people who came up with ideas about how the world might work and designed experiments to systematically test those ideas were called natural philosophers, so I suppose I understand why you feel the line is a bit blurry.(3 votes)
- I didn't exactly understand the "dark energy" everyone's been talking about. Could anyone of you please elaborate?(2 votes)
- Dark energy is just a placeholder term for the force that is currently driving the acceleration of the expansion of the universe.(6 votes)
- How exactly do you find out what the universe is made of? Is it a sort of mathematical equation? Or is it more like just providing an answer and checking if it's correct?(2 votes)
- I'm assuming you are talking of things such as energy and atoms and elements.
Yes, over thousands of years, people basically have used their observations to come up with theories about what the universe is made of and how it works. At first they came up with myths and tales of magic that became religion, but during the Scientific Revolution the idea came up that if someone were to make a claim about how the universe works, they had to prove it using observations and solid evidence. If a theory turns out to be incorrect when a certain experiment is run, that theory is modified or scrapped. And yes, mathematical formulas can also describe various phenomena.
In recent times, things such as powerful spectroscopes, microscopes, and telescopes have allowed us to study the universe in more detail and see if our theories are correct.
I hope this answered your question.(5 votes)
- What might the 4th dimension be like?(3 votes)
- It is time on rails. The 4th dimension is everything in the future and the past. It gets harder to understand the higher the number.(2 votes)
- Didn't Albert Einstein say that the fourth dimension is time?(3 votes)
- The 1st dimension is length
The 2nd dimension is width
The 3rd generation is depth
The 4th dimension is time(2 votes)
- what is 4 dimension? if three dimensions contain length,breadth and height(3 votes)
- The fourth dimension is time(2 votes)
- Learning AstroPhysics in Arts and humanities section huh? I am kinda confused.(1 vote)
- Me too. I think there should be an entire Astrophysics course on Khan Academy, and should include Astronomy and Cosmology in it.(4 votes)
Video transcript
I'm Janna Levin and I'm a professor
of physics and astronomy at Barnard College
and Columbia University and I primarily
study astrophysics. And astrophysics is really
very much rooted in physics, the study of physical laws and how mathematics
actually describes natural phenomena and laws. But it's applied to
the Universe as a whole, not just the things
in it-- stars, galaxies, the things that we observe
at very great distances-- but also space itself, space and time and
how space time evolved and even how the Universe
began and was created. So, astrophysics has
this very beautiful setting in which to study physics, from which to study the
fundamental natural laws. In physics, there's
kind of a distinction in people who work in physics
between experimentalists, observers, and theorists. Experimentalists build things
to try to make detections, to confirm and gather evidence. Observers will often use
things like telescopes to look out into the sky and hopefully receive
something from the cosmos that's new and never
been seen before. And then there's theorists,
such as myself, who often sit quietly with a pen
and paper, maybe a computer, and use the mathematics
to try to make discoveries, to talk to the observers, and maybe make suggestions
for what they could look for. And then there are
people who do all three and can combine
all those skills. But there's a real
conversation between doing the math,
making a prediction, going to the observers
to make an actual observation, or building an experiment
and vice versa. Sometimes there are
discoveries made with telescopes
that we just didn't foresee and then we have to go
back to our pen and paper, back to the drawing board and
figure out what did we miss and how could we not have
predicted this phenomenon? And then often, it goes that way that we're trying to understand
something we've seen in the world but
don't yet understand. So, astrophysics draws from a
lot of different kinds of study and I actually came to realize that this was this
beautiful field kind of late. I was not interested in physics
when I was a student. I was not one of those kids in the basement
with a chemistry lab and I didn't
understand or appreciate how elegant and beautiful
science was until much later. I wouldn't say I had
a fear of mathematics but I didn't recognize
how rich and beautiful it was. And it wasn't
until later when I understood that mathematics
gives us this kind of... it's a gift that connects
us to the natural world that somehow,
through mathematics, we're able to understand natural phenomena
and then that's just remarkable and that it's the same
wherever you are in the world and it's the same
with the other side of the Universe, you know,
one plus one is still two. So, there's something that
connects all of us there that seems really important. And when I discovered
that in college, I became completely
enamored of physics and math and astronomy and I
started to study astrophysics. And now, I work
on questions like, "How did the Universe begin?"
and, "How is it evolving?" and, "How many dimensions are there? Are there more than three
dimensions in the Universe?" and, "What's
the Universe made of?" because the most important
questions right now seem to be bound to an attempt
to understand what the Universe is made of because we've realized
that most of the Universe is in a form of
matter and energy that we've never seen before
because it's literally dark. We cannot see it
with our telescopes. But we know it's out there because we can see
the effect it has on galaxies and on the expansion
of the Universe. And so we deduced that this energy is out there
and this matter is out there but, amazingly, it is nothing
like any kind of matter energy we've ever seen before. And so, it's a very
big question that says, by studying astrophysics,
we're learning about the deepest underlying principles in
nature that are fundamental to how the Universe
began and evolved.