Stars and the Universe(Great Discoveries in Astronomy and Astrophysics)

171.118Professor Adam Riess

Primary resourcewith explanations ($14)

Typical Astronomy TextbookNot required ($70-$180)

“Popular” Book on discoveries— great images, figures($31)

Course Preliminaries

• Who am I? Who are you? Why are you here?• Meeting time (MW 1:30-2:45), Office Hours (Thursday 2pm, Rm 207)

Syllabus (hand out, also on course website)

• 3 Texts, 2 required, 1 recommended-• Website: http://braeburn.pha.jhu.edu/~ariess/stars_universe/ or follow link in blackboard.jhu.edu. Homework, labs,

etc will appear there

• Head TA: David Jones, djones@pha.jhu.edu, plus 3 others• Homework• Grading• Class Participation-polling with clickers (go to blackboard.jhu.edu to register)• Labs--observing with Galileoscope, roof telescope.• Etc, etc

Today Theme: Discoveries, small tour Reminder of scientific notation, math Ancient knowledge

Expanding Enrollment !? Nobel Anomaly?

In this course you will learn a lot about our Universe, but• If you don’t put in effort, you will do poorly• The grade distribution is typical of JHU, not all A’s• There is math in this course… algebra I and a little geometry•EVERYTHING SHOULD BE MADE AS SIMPLE AS POSSIBLE, BUT NOT SIMPLER!—ALBERT EINSTEIN

“Nobel Anomaly”

2015

This Year

How much math? What math is hard?

--“I personally found that the course is too conceptual and not mathematical enough. “

--“You will need to know a lot of math. Not good if you're a humanities/social science major who hasn't done math in a while.”

--“There should be two classes. One for students with backgrounds in physics and math that want to learn about the universe. And a separate one that is like the current one.”

--“Beware if you are uncomfortable with math! - This class is not easy although people feel it is. “

--“Some basic math is useful to have, but there is ample review.”

“Don't let the math intimidate you. A lot of people freak out about it, but it's no more than simple algebra.”

--“misleading when you are told in the first class that it contains only simple math. “

----“Definitely the best class of my semester, no experienced or really tough math thinking at all, very fun! “

--” This course is not very difficult. You only need to know a little pre-algebra and high school physics to understand the material.”

--” The more math and physics you know, the easier this course will be. However, you can certainly get by with a high school background.”

An Example:

Class Participation

• a few questions per class to gauge our comprehension, respond with remote.• get a remote at bookstore (can trade in old ones…) or anywhere online• Register remote to class at blackboard.jhu.edu (before class)

• New Remotes: just turn on to join, click answer, look for check mark

• Your participation grade based on attempting to answer the questions, not whether you get the answer right or wrong .

(if you forget your remote, remember it next time. I’ll drop lowest two days so don’t worry :)• practice today, start counting next time

More Resources

wikipedia.org--good to fill ingaps in knowledge, bad when youneed to be sure

Individual or Paired Observing with Telescope, tripod..example

Galileoscope

Stars and the Universe,Wordle from prior year’s Evaluations

Stranger than Fiction - The déjà vu Supernova

“Place three grains of sand inside a vast cathedral, and the cathedral will be more closely packed with sand than space is with stars”-- James Jeans

“The effort to understand the universe is one of the very few things that lifts human life a little above the level of farce, and gives it some of the grace of tragedy” --Steven Weinberg

“In science one tries to tell people, in such a way as to be understood by everyone, something that no one ever knew before. But in poetry, it’s the exact opposite”. -- Paul Dirac

“The most incomprehensible thing about the universe is that it is comprehensible” -- Albert Einstein

Cosmic Inspiration

What are discoveries & why study them?• What is a cosmic discovery? “A new theory or cosmic feature

once revealed will have fundamental effects on how we view our place in the Universe.” --Bartusiak

• Paradigms and principles, not just facts (digits, moons). We will focus on deduction not detail. Our focus in this class is on how we know what we know not just what we know.

• Discoveries: We will address underlying science principle, historic context, the original work and how it is understood today

• Note, not all discoveries turn out to be right!

Famous Discoveries•Neptune•Gamma ray bursts•Expansion of Universe•Extra-solar planets•Black Holes•Dark matter•Dark Energy

Infamous “Discoveries”•Ptolemaic model•Steady-state Universe•Epicycles•Vulcan•Nemesis-death star•Canals on Mars•Cold Fusion•Aether

Example: Percival Lowell and Canals on Mars1855-1916

Astronomer, founded Lowell Observatory in Flagstaff, AZ.Convinced bands seen on Mars were canalsbuilt by Martians to draw limited water supply from Poles.Later discredited by improved imaging, landings

Nemesis the Death Star

• Hypothetical binary companion to Earth, (e.g., Brown Dwarf),

1-1.5 light years away at present. Invented in 1984 (Whitmire and Jackson, Nature) to explain 26 million year period in mass extinctions--when Nemesis dislodges comets in Oort Cloud which crash into the Earth.

No direct proof of Nemesis ever found. Periodicity in extinctions now disputed.

The Seeds of Galaxies

• Launched in 1989 by NASA, COBE found the relic “seeds” which grew up to become the galaxies of the modern Universe. Awarded Nobel Prize in Physics in 2006.

Front pageof NYT in 1992!

Dark Energy and the Accelerating Universe

Nobel Prize in Physics 2011For discovering that the expansion rate of the universe is accelerating, through the observations of distant supernovae.

Translation: Universe full of “Dark Energy” accelerating the Universe

Where are Discoveries made? Where are Discoveries made?

e.g., here: Einsteine.g., here: Einstein’’s Blackboard 1931s Blackboard 1931

. Ruthless use of logic, math, deduction…

Others are made here:

Pictured: Edwin Hubble showed that the Milky Way was not the whole Universe.

He showed we live in a Universe of galaxies, each equivalent to the Milky Way,

most rushing away from us due to expansion of Universe

Or here by graphing and analyzing data:

Technology can drive discovery.New telescopes, instruments, detectors, computers, satellites,etc often lead to immediate discoveries.

Others are made when theorists and observers compare ideas to data at places like this

Einstein visits Mt Wilson in 1931

Theory may suggests possibilities, observations may reject all but one.

HubbleEinstein

Theme: Most of The Discoveries we Theme: Most of The Discoveries we will discuss involve finding our place will discuss involve finding our place here and its place out therehere and its place out there

The Milky WayThe Milky Way

You are here

Bold, Cosmic Questions We Will Consider

• What is out there? (The Cosmic Zoo, Life)• Where is everything located? (Where do we fit in?)• How is it all moving? • What patterns are in the motions?• How does everything interact?• How does everything work?• What is everything made of?• How long has this been going on? Future?

Theme: Much of cosmic discovery can be thought of as the quest for depth perception in the Universe (imagine yourself as an ant on a cosmic anthill…)

Discovering The Origin of You

We are made of starstuff,leftovers from the Big Bangand supernova spew!

Make upof humanbody

Why So Hard to Understand the Universe?

We May Not Be Seeing the Whole Picture

Imagine you were a 1-dimensional creature living along a line-Universe

Carriers Of Information Across Universe

1. Electromagnetic Information: gamma rays, x-rays, uv, visible and ir light, microwaves, radio waves

2. Cosmic-ray Particles: nuclei, protons, and electrons traveling fast, short-range

3. Solid bodies: meteors and meteorites (so far only within solar system)

4. Neutrinos: light weight particles without charge (seen from Sun, SN 1987A)

5. Gravity waves: ripples in space-time, predicted but not yet detected

Increasing Rate of Cosmic Discovery

From Cosmic Discovery (1981), M. Harwit, pace of discovery increasing. Rediscoveries used to predict we have found ~35% of all cosmic phenomenaMost discoveries made within ~5 years of development of new technology.

•Dark Matter•Gravitational Lensing•Large-scale structures•Inflation•Neutrino Astronomy•Galaxy Evolution•Extra-solar Planets•Dark Energy

From Archives (2004)

No sense of scale: Are these Big or Small? What made these? (Earthly intuition fails us!)

One of these contains billions of the other. Which one?

A B

Test Remote Question

The correct order from smallest to largest is:

a) Milky Way, Sun, Orion Constellation, Jupiter, Pluto

b) Jupiter, Pluto, Milky Way, Sun, Orion Constellation

c) Pluto, Jupiter, Sun, Orion Constellation, Milky Way

d) Sun, Pluto, Jupiter, Orion Constellation, Milky Way

The answer is c)