Astro 105: The Milky Way

Lecture I: Introduction

Science and the Human Prospect *

*This is the title of an out of print book

by R. C. Pine from which I will draw some of

my lectures from.


The realities of Nature surpass even our wildest dreams
August Rodin

Section I: A Some Definitions

  • What are we doing here?
    • We're here to study the Milky Way galaxy and everything it .
    • That includes US!
    • The Milky Way is our local city of stars. Its composed of stars, planets, gas, dust, light and some mysterious stuff called "dark matter"

Planets, Stars, Galaxies...
So which is which?

(In the pictures below L = characteristic size scale. From here on out we are going to be using "Scientific Notation" to represent big numbers. Here is an example of scientific notation. The number one hundred thousand is 1 with 5 zeros after it or --> 105 = 100,000 )
L = 10 22 cm
A galaxy is a collection of billions of stars (and other stuff) bound by their mutual gravitational attraction
L = 10 26 cm
Their are billions and billions of galaxies in the KNOWN Universe. They come in a variety of shapes and sizes
L = 10 10 cm
Stars are giant spheres of gas (mostly hydrogen and helium) which shine via nuclear fusion in their cores

L = 10 8 - 10 9 cm
Planets are rocky or gaseous spheres which form around stars.
L = 10 19 cm
In between the stars are vast clouds of interstellar gas and dust. Some of these are the remnants of dying stars some are wombs of pre-natal stars
L = 10 19 cm
Along with matter and light there is also exotic kinds of stuff out there: Anti-matter, Dark-matter...

So Why Study This Stuff?

"Somewhere, there is something incredible waiting to be known"
carl sagan

 You can ask this question 2 ways.

a.       Why should you as an individual care?

b.      Why should we as a culture or society care (and pay for it)

In some sense the answers will be the same since they always hinge on the concept of the Truth and its worth.


Physics, Astrophysics and the Individual
"Man Differs from the Animal only a little; most people throw that
little away"

Confucius

News flash! You are going to die.

Most of Life is mysterious, Astronomy and AstroPHYSICS puts that mystery into the context of an even greater mystery: that of BEING as a whole. Astronomy asks fundamental questions about the PHYSICAL component of existence.

The current age of the Universe is between 10 and 20 billion years.

tUni = 1010 = 10,000,000,000 You, on the other hand be will be lucky to make it to 100. tYou = 102 = 100 The Cosmic Calendar: If we consider the whole time the Universe has existed to be a single year with the "Big Bang" occurring on New Years then here is how the landmarks of Universal History play out
 

Date 

Event

Origin of Universe 

Jan 1 

Origin of Milky Way Galaxy 

May 1 

Origin of Solar System 

Sept 9 

Formation of Earth 

Sept 14 

Sexual reproduction by micro-organisms 

Nov 1 

Land Plants 

Dec 19 

First Dinosaurs 

Dec 25 

Dino Extinction 

Dec 28 

First Primates 

Dec 30 

Australopithicenes (Lucy) 

10:00 pm Dec 31 

Homo Erectus 

11:40 pm Dec 31 

Homo sapiens sapiens 

11:58:57 pm Dec 31 

Greeks to modern era 

11:59:55 - 

Average Human Life Span 

.1 second 

 


OK, so what we have is the fact that we are pretty small in the scheme of things. This can be a disconcerting to some or a comfort.

To me its comforting. The Universe is so vast who cares if my sink leaks or if my tires are flat!

The size and age of the Universe are so incomprehensible we are forced out of our mundane everyday way of viewing the world. This is a good thing.

"A scientist is ... a learned child. There is something of the
scientist in every child. Others must outgrow it. Scientists can stay that
stay that way all their lives"

george wald

"Sit down before fact as a little child, be prepared to give up
every preconceived notion, follow humbly wherever and to
whatever abyss nature leads, or you shall be nothing"

T.H. Huxley

                                            "You shall know the truth and the truth shall make you free"

The Bible

"Its the questions you should love."

rilke

Physics, Astrophysics, and Metaphysics
OK so what is the Truth?

There are different Kinds of Truth:

  • Emotional - "I Love You"
  • Religious - "And God said ____" Buddhist, Jewish, Christian, Muslim ...
  • Artistic - "To be or not to be"
  • Financial - The Law of Supply and Demand

What makes Physics (Science in general) so powerful and, perhaps unique, is its claim to be able to determine principles, laws, truths about the physical world.
 

  • This is claim is held to be universal.
  • The Law of Gravity should be the same for everyone, everywhere.
  • Science is held to be an empirical (based on experiment) means for determining the structure or behavior of the World.

For many people Science describes the Reality : "Just the Facts"

Is this true? Does such a thing even exist?

A New Concept:
The EIOR
External Independent Objective Reality

External = Outside our heads. Its there even if we aren't.

Independent = Our culture or color shouldn't matter.         The EIOR is the same for everyone even extra terrestrials (an important point for SETI).

Objective = There is a way of asking questions about it that provides universally true answers.

Reality = What exists, what is.

The EIOR is the "Ideal" of Science. It is what many of us think we are reaching and can, in fact, grab!

One of the questions we will be exploring in this class through the lens of astronomy and astrophysics is:


Is there such a thing as an EIOR and does science have access to it?


Currently Science is under attack from scholars in the Humanities claiming that Science is just a "culturally created" system of rules and knowledge.

According to this view Science has no special claim to the Truth.

Is Physics and Astrophysics just our culture's Myth System?

Zeus, ruler of greek pantheon

Physics, Astrophysics, and Society
  

"The dangers that face the world can, every one of them, be traced

 back to science.  The salvation's that may save the world will, 

everyone one of them, be traced back to science

issac asimov
Is the first part of this quote true? How about the second part?

 

 

New Problem

CLIMATE CHANGE + RESOURCE DEPLETION = The Long Emergency

 

 

Why do we as a Culture support science?

The Hubble Space Telescope cost more than 1 billion dollars to build.

Think of how this money could be used to combat poverty and homelessness

Or what would happen if even a fraction of this was put towards the budget for the National Endowment for the Arts...

But as a Culture we do get some really cool things out of the 1 billion investment like ...


So...Is it worth it?

 

Senator to Scientist at Budget Hearing: "Sir how does your research contribute to the national defense?"

Scientist: "It makes the country worth defending."

Two traditional answers to the question: The God Gambit and the Widget Excuse

God Gambit: We are human and it is our fundamental nature to be curious. We must explore just as we must breathe.

In a thousand years the United States of America won't be remembered for producing The Simpsons,

(not that it isn't a great show).

We will be remembered for what we have done in Science which has been profound.

A billion dollars to get a mystical feeling? Shouldn't we just go to church or read poetry. Can't feel just as inspired by feeding the hungry?

 

The Widget Excuse: You have to fund basic or "blue-sky" research because you never know where it will lead.


Spin-offs:

Teflon, the non-stick material on most frying pans was invented for use on space capsules in the Apollo space program in 1960's.


 

 

When it was invented in the late 1950s the Laser was considered to be just a artifact of basic physics without any practical use. Now its at the heart of billion dollar businesses (CDs, Supermarket scanners, etc.)


 

 

A billion dollars is a lot to pay for a non-stick frying pan coating? Can't we figure out what we need and then go and invent it without the expensive extra step?

 


 

 

The Third Justification:

 

Because We're Going!: Sooner or later, if we don't wipe ourselves out, we are going to be exploring and colonizing Space. First its going to be the neighborhood - the solar system. Then it will be our section of town - the local stars. Finally it will be the whole city - the Galaxy. Its going to happen and what we are doing with astronomy and astrophysics is surveying.

For instance: Pulsars - nasty dead stars which produce superstrong gravitational and magnetic fields.
 


 

Pulsars Ahead
Beware

So...

What do You Think?