Astronomy: A Search for Origins!!!

Where did all the structure and organization come from?

How did it emerge over time?

What physics/physical processes were important?
Hydrogen + Helium + Gravity Stars, Galaxies, and Humans
given about 14 billion years.
A Five-Minute History of the Universe

The “Big Bang” brings matter, space and time into existence.


a number now known to better than 1 percent!


Stars “process” Hydrogen and Helium into heavier elements like Iron,
Calcium, and Oxygen.
After 9 billion years of cosmic recycling (4.6 billion years ago) our Sun
forms from the “ashes” for previous generations of stars.


The early Universe contained only uniformly distributed Hydrogen and
Helium.
Almost immediately gravity begins to form stars and galaxies.


It happened 13.7 billion years ago.
At the same time system of planets form from debris left in orbit around the
Sun.
Life originates quickly on Earth.

but only becomes “complex” ½ billion years ago.
Lecture outline: A Brief Brief History of the Universe
A Five-Minute History of the Universe

The “Big Bang” brings matter, space and time into existence.


a number now known to better than 1 percent!


Stars “process” Hydrogen and Helium into heavier elements like Iron,
Calcium, and Oxygen.
After 9 billion years of cosmic recycling (4.6 billion years ago) our Sun
forms from the “ashes” for previous generations of stars.


The early Universe contained only uniformly distributed Hydrogen and
Helium.
Almost immediately gravity begins to form stars and galaxies.


It happened 13.7 billion years ago.
At the same time system of planets form from debris left in orbit around the
Sun.
Life originates quickly on Earth.

but only becomes “complex” ½ billion years ago.
Lecture outline: A Brief Brief History of the Universe
A Five-Minute History of the Universe

The “Big Bang” brings matter, space and time into existence.


a number now known to better than 1 percent!


Stars “process” Hydrogen and Helium into heavier elements like Iron,
Calcium, and Oxygen.
After 9 billion years of cosmic recycling (4.6 billion years ago) our Sun
forms from the “ashes” for previous generations of stars.


The early Universe contained only uniformly distributed Hydrogen and
Helium.
Almost immediately gravity begins to form stars and galaxies.


It happened 13.7 billion years ago.
At the same time system of planets form from debris left in orbit around the
Sun.
Life originates quickly on Earth.

but only becomes “complex” ½ billion years ago.
A Five-Minute History of the Universe

The “Big Bang” brings matter, space and time into existence.


a number now known to better than 1 percent!


Stars “process” Hydrogen and Helium into heavier elements like Iron,
Calcium, and Oxygen.
After 9 billion years of cosmic recycling (4.6 billion years ago) our Sun
forms from the “ashes” for previous generations of stars.


The early Universe contained only uniformly distributed Hydrogen and
Helium.
Almost immediately gravity begins to form stars and galaxies.


It happened 13.7 billion years ago.
At the same time system of planets form from debris left in orbit around the
Sun.
Life originates quickly on Earth.

but only becomes “complex” ½ billion years ago.
Lecture outline: A Brief Brief History of the Universe
A Five-Minute History of the Universe

The “Big Bang” brings matter, space and time into existence.


a number now known to better than 1 percent!


Stars “process” Hydrogen and Helium into heavier elements like Iron,
Calcium, and Oxygen.
After 9 billion years of cosmic recycling (4.6 billion years ago) our Sun
forms from the “ashes” for previous generations of stars.


The early Universe contained only uniformly distributed Hydrogen and
Helium.
Almost immediately gravity begins to form stars and galaxies.


It happened 13.7 billion years ago.
At the same time system of planets form from debris left in orbit around the
Sun.
Life originates quickly on Earth.

but only becomes “complex” ½ billion years ago.
Lecture outline: A Brief Brief History of the Universe
A Five-Minute History of the Universe

The “Big Bang” brings matter, space and time into existence.


a number now known to better than 1 percent!


Stars “process” Hydrogen and Helium into heavier elements like Iron,
Calcium, and Oxygen.
After 9 billion years of cosmic recycling (4.6 billion years ago) our Sun
forms from the “ashes” of previous generations of stars.


The early Universe contained only uniformly distributed Hydrogen and
Helium.
Almost immediately gravity begins to form stars and galaxies.


It happened 13.7 billion years ago.
At the same time a system of planets form from debris left in orbit around
the Sun.
Life originates quickly on Earth.

but only becomes “complex” ½ billion years ago.
Lecture outline: A Brief Brief History of the Universe
A Five-Minute History of the Universe

The “Big Bang” brings matter, space and time into existence.

It happened 13.7 billion years ago.
 a
number now known to better than 1 percent!
Stars
die


Almost immediately gravity begins to form stars and galaxies.


The early Universe contained only uniformly distributed Hydrogen and
Helium.
Stars “process” Hydrogen and Helium into heavier elements like Iron,
Calcium, and Oxygen.
After 9 billion years of cosmic recycling (4.6 billion years ago) our Sun
forms from the “ashes” of previous generations of stars.

At the same time a system of planets form from debris left in orbit around
the Sun.
Stars
form

Life originates quickly on Earth.

but only becomes “complex” ½ billion years ago.
Lecture outline: A Brief Brief History of the Universe
A Five-Minute History of the Universe

The “Big Bang” brings matter, space and time into existence.


a number now known to better than 1 percent!


Stars “process” Hydrogen and Helium into heavier elements like Iron,
Calcium, and Oxygen.
After 9 billion years of cosmic recycling (4.6 billion years ago) our Sun
forms from the “ashes” for previous generations of stars.


The early Universe contained only uniformly distributed Hydrogen and
Helium.
Almost immediately gravity begins to form stars and galaxies.


It happened 13.7 billion years ago.
At the same time system of planets form from debris left in orbit around the
Sun.
Life originates quickly on Earth.

but only becomes “complex” ½ billion years ago.
Lecture outline: A Brief Brief History of the Universe
A Five-Minute History of the Universe

The “Big Bang” brings matter, space and time into existence.


a number now known to better than 1 percent!


Stars “process” Hydrogen and Helium into heavier elements like Iron,
Calcium, and Oxygen.
After 9 billion years of cosmic recycling (4.6 billion years ago) our Sun
forms from the “ashes” for previous generations of stars.


The early Universe contained only uniformly distributed Hydrogen and
Helium.
Almost immediately gravity begins to form stars and galaxies.


It happened 13.7 billion years ago.
At the same time system of planets form from debris left in orbit around the
Sun.
Life originates quickly on Earth.

but only becomes “complex” ½ billion years ago.
Lecture outline: A Brief Brief History of the Universe
A Five-Minute History of the Universe

The “Big Bang” brings matter, space and time into existence.


a number now known to better than 1 percent!


Stars “process” Hydrogen and Helium into heavier elements like Iron,
Calcium, and Oxygen.
After 9 billion years of cosmic recycling (4.6 billion years ago) our Sun
forms from the “ashes” for previous generations of stars.


The early Universe contained only uniformly distributed Hydrogen and
Helium.
Almost immediately gravity begins to form stars and galaxies.


It happened 13.7 billion years ago.
At the same time system of planets form from debris left in orbit around the
Sun.
Life originates quickly on Earth.

but only becomes “complex” ½ billion years ago.
A Single-Year Perspective

If this history could be compressed into a single year:

The Universe starts on January 1...

The Solar System forms in early-September
A Single-Year Perspective

If this history could be compressed into a single year:

The Universe starts on January 1...

The Solar System forms in early-September

Life originates in mid-September
–
3.4 billion year old
stromatolite fossils
UR
L
- Life becomes complex in early-December
0.3 billion year
old trilobyte
A Single-Year Perspective

If this history could be compressed into a single year:

The Universe starts on January 1...

The Solar System forms in early-September

Life originates in mid-September
–

- Life becomes complex in early-December
Dinosaurs roamed the Earth for two weeks between December 10
and December 25

Humanity (intelligence?) arose at 10 p.m. on December 31

Recorded history began around 11:59:45 on December 31
Overcoming Human Biases

Location, Wavelength, and Time to name a few
Lecture Notes: Human Biases in Astronomy
Human Biases


Time

A human lifetime is a blink of the eye relative to the timescale of
cosmic events.

Astronomers must reconstruct the workings of the Universe from this
“snapshot” view.
This task is similar to reconstructing the intricacies of human
relationships and politics from a snapshot of the events happening on
Earth at one instant.
Lecture Notes: Lookback time
Human Biases

Time

A human lifetime is a blink of the eye relative to the timescale of
cosmic events.

Astronomers must reconstruct the workings of the Universe from this
“snapshot” view.


This task is similar to reconstructing the intricacies of human
relationships and politics from a snapshot of the events happening
on Earth at one instant.
Astronomers have two powerful tools to address this shortcoming

Light travels “slowly”. A stale view of the universe permits
Astronomers to look back in time.
Lecture Notes: Lookback time
“Lookback” Time

Light takes time to get from one place to another.



Light travels at a speed of 300,000 km/s
The travel time is instantaneous for most everyday experience where
distances are small.
Travel time becomes important for more distant objects


Light takes just over a second to get to the Moon (400,000
kilometers away).
In a year light traverses a distance of a light-year.
“Lookback” Time


We see the Sun as it was 8.3 minutes ago because the light took 8.3
minutes to traverse the distance from the Sun to the Earth (150
million kilometers).
For extremely distant objects, billions of light-years, the light takes
billions of years to get here, bringing a view that is billions of years
out of date.

We see the distant universe as it was in the distant past.
“Lookback” Time


We see the Sun as it was 8.3 minutes ago because the light took 8.3
minutes to traverse the distance from the Sun to the Earth (150
million kilometers).
For extremely distant objects, billions of light years, the light takes
billions of years to get here, bringing a view that is billions of years
out of date.

We see the distant universe as it was in the distant past.
Human Biases

Time

A human lifetime is a blink of the eye relative to the timescale of
cosmic events.

Astronomers must reconstruct the workings of the Universe from this
“snapshot” view.


This task is similar to reconstructing the intricacies of human
relationships and politics from a snapshot of the events happening
on Earth at one instant.
Astronomers have two powerful tools

Light travels “slowly”. The stale view of the universe permits
Astronomers to look back in time.
Radio observations can detect light originating from the warm, glowing
universe shortly (300,000 years) after the Big Bang
Human Biases

Time

A human lifetime is a blink of the eye relative to the timescale of
cosmic events.

Astronomers must reconstruct the workings of the Universe from this
“snapshot” view.


This task is similar to reconstructing the intricacies of human
relationships and politics from a snapshot of the events happening
on Earth at one instant.
Astronomers have two powerful tools to address this shortcoming

Light travels “slowly”. A stale view of the universe permits
Astronomers to look back in time.

Computer simulation can permit scientist to watch events play out
over millions or billions of years.

Insert the laws of physics and turn the crank...
Lecture Notes: Lookback time
Simulation
Real
Some computer animations:
Collision between Galaxies
Formation of Structure in the Universe
Simulation
Real
Some computer animations:
Collision between Galaxies
Formation of Structure in the Universe
Tour the Millenium Simulation
Human Biases

Location
Human Biases

Location
Human Biases

Location
Human Biases

Location


High density of matter compared with intergalactic space.

1019 atoms per cubic centimeter in air.

1 atom per cubic “stadium” in intergalactic space.
High temperature compared with intergalactic space

300K room temperature vs. 3K elsewhere.
Human Biases

Location
Human Biases

Wavelength
Human Biases

Wavelength

The universe looks quite different when we look outside the tiny
slice of the spectrum accessible to the human eye.
Human Biases

Wavelength
Human Biases

Comprehending large numbers

It's easy to visualize 5, 10, or even 100 things.


What's the difference between a million, a billion, or a trillion (from
a visualization standpoint)
How do we make large numbers conceptually meaningful?
Human Biases

Comprehending large numbers

It's easy to visualize 5, 10, or even 100 things.


What's the difference between a million, a billion, or a trillion (from
a visualization standpoint)
How do we make large numbers conceptually meaningful?

The mass of the Sun is
2,000,000,000,000,000,000,000,000,000,000 kg

Using scientific notation makes the above number manageable, but
not necessarily comprehensible.
= 2 x 1030 kg
Human Biases

Scale models can put these numbers in a relative context.
Human Biases

Scale models can put these numbers in a relative context.
NO!