Transcript The Nature of Space and Time

ASTRONOMY 112
Stars, Galaxies, and Cosmology
INTRODUCTION
The Nature of Astronomy and Astronomy By Definition
Scale, Structure, and a Tour of the Universe
The Hierarchy of the Distribution of Matter
Fundamental Forces
The Seven Unique Things in the Universe
Scale of the Cosmos
Powers of Ten
Composition of the Cosmos
The Nature of Space and Time
The Nature of Astronomy
“Looking at the stars always makes me dreamas simply as I dream over the black dots
representing towns and villages on a map. Why,
I ask myself, shouldn’t the shining dots of the
sky be as accessible as the black dots on the map
of France?”
Vincent Van Gogh
1889
The Nature of Astronomy




The inaccessibility of cosmic phenomena is one of the
most intriguing features of the study of astronomy
Although technology has greatly increased since the
time of the ancients, astronomy remains primarily a
passive science
Experimental, Empirical but Primarily Observational
Science
Still provides great insight into the origin, history,
evolution, and underlying physics and chemistry of
celestial phenomena and the universe itself…
The Nature of Astronomy





Since pre-history people have gazed into the sky and
pondered the nature of the universe
All early civilizations studied the stars and the motions
of the five naked-eye planets known to them as the
“wanderers”
They used their observations to tell time, for
navigation, to predict the coming of seasons, to explain
eclipses, and to reinforce their religious beliefs
Now, we apply empirical methods of science to
understand the physical nature of these phenomena
Now, we can explore with humans, robotically, and
passively from great distances
Pseudoscience vs. Real Science




Astronomy, By Definition
Astrology, By Definition
Empirical Science vs. Pseudoscience
Scientific Models and Testing
Astronomy, by Definition
the science concerned with celestial objects along
with the observation and interpretation of the
radiation from the component parts of the universe
Astrology, by Definition
the ancient belief that the positions of the sun, moon, and
planets with respect to the zodiac influenced earthly
affairs and human lives
Astronomy, Astrophysics, and
Cosmology





Golden Age of Astronomy
NASA’s Great Observatories
Enormous telescopes worldwide and on orbit
New Generation of Extremely Large Telescopes
Planned
Still, fundamental secrets of the universe remain
mysterious
The nature of dark matter, dark energy
 Era of the first stars
 The evolving decelerating, then accelerating universe

The Structure of the Universe







Is the universe continuous, or discontinuous?
Is the universe homogenous or inhomogeneous?
Does the universe end?
Levels in the hierarchy
Fundamental forces that govern everything
GUTS and TOES
Laws of physics are ubiquitous
Hierarchy of the Distribution of
“Luminous” Matter






From quarks to the cosmos…
12 levels in the hierarchy…
Fundamental Forces
Cosmic Irony: The simplicity and complexity of
the universe...
Scale of the Cosmos
Luminous matter does not include “dark”
components
The Structure of Everything
Quarks: SN
(10-16 meters)
p+ = 2 up + 1 down
n = 2 down + 1 up
Subatomic Particles: SN
(10-15 meters)
Atoms: EM
(10-13 meters)
There are four fundamental forces in nature
1. Gravity
2. Electromagnetic (EM)
3. Strong Nuclear (SN)
4. Weak Nuclear
Molecules: EM
(10-9 meters)
Matter (stuff): Gravity
(100 meters)
Planets: Gravity
(107 meters)
Solar System: Gravity
(1014 meters)
Star Clusters: Gravity
(1018 meters)
Galaxies: Gravity
(1020 meters)
Galaxy Clusters: Gravity
(1021 meters)
Super Clusters: Gravity
(1023 meters)
Universe: Gravity
(1025 meters)
Scale of the Cosmos

Supplemental Presentation…
Powers of Ten

Supplemental Video…
The Universe in a Nutshell
Matter
Energy
Dark
Matter
Dark
Energy
and
Size of the Universe

Supplemental Presentation…
The Nature of Space and Time



Space and Time are Different Aspects of the
Same Phenomenon
Into the Past
Light Travel Time and the History of the
Universe
Into the Past
Time required for light to travel
to earth
Moon
Sun
Centauri
1.25 seconds
8.5 minutes
4.5 years
Betelgeuse
Milky Way
Andromeda
1,200 years
100,000 years
2.2 million years
Virgo Cluster
Hydra Super Cluster
60 million years
3 billion years
Quasars
Cosmic Microwave
Background (CMB)
13 billion years
13.5 billion years