Beginnings - Origin of the Universe and Solar System

 

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General Statements

Books make many statements as though they are facts, as opposed to ideas

Many based on complex mathematical models

It's important to keep in mind that this happened a long time ago

There are no direct methods to observe the formational process of the universe

So, let's keep the uncertainty factor in mind

 

Study of the sky has always fascinated humans

Before electric lights and TV, its just about all there was to do at night

Look into the sky and it is obvious that there are many objects out there

In our immediate vicinity describe solar system

In the distance

Countless stars, clusters, and galaxies (show poster of M-31)

Milky Way: our galaxy (with >10 billion stars)

Our sun is an 'average' star

Rather insignificant

Way out on a spiral arm - like Luke Skywalker's home planet

The "known" universe is truly immense

Estimate billions of galaxies in universe

Widely spaced islands of stars in the vast void of space

How about other planets?

3 X 1010 galaxies

1X 1011 stars per galaxy

1 X 101 planets per star

...equals a lot of stuff (3 X 1022 planets possible)

Distances measured in Light Years: Light speed (186,000 miles per second)

We look back in time as we look out into the universe

See it as it was, not as it is: even the sun is 8 minutes old news!

And everything is changing position

How fast are you moving?

All speed approximate and in miles per hour (J. Michener: Space, pg. 585)

Rotation of Earth . . . . . . . . . 800
Revolution around sun . . . . . .66,661
Sun moving towards Vega . . . . .31,000
Local group of stars moving . . 700,000
Rotation of Galaxy. . . . . . . 560,000
Movement of Galaxy. . . . . . 1,000,000
Total . . . . . . . . . . . . 2,360,000

And there are surely additional motions to take into account at larger-than-galactic scales!

This can really foul up our perceptions of space, time, and reality!

 

Mechanics of the universe

This is where some of the heavy-duty laws of nature come into effect

Sir Isaac Newton (1642-1727)

Newton's "Universal" Law of Gravitation: G=M1M2/D2

Three Laws of Motion

1st Law: Inertia

"A body continues in its state of rest, or of uniform motion in a straight line, unless it is acted upon by a net external force"

2nd Law: Force = mass X acceleration

"When an unbalanced force acts on a body, the body will be accelerated"

3rd Law: Law of action and reaction

"For every action there is an equal and opposite reaction"

A single force cannot exist. Every force is accompanied by an equal and opposite force

These work well for most of what we have to deal with

Start to break down when we get too big or small, or try to go too fast

Albert Einstein: early 1900's

Matter and energy are interchangeable (E=MC2)

Click here to go to the Astronomy section which deals with this topic

 

Formation of the Universe

There are two possibilities

1) Everything always existed like it is today, and time has no beginning, or

2) The universe (and time) began at a specific moment, and has been evolving and changing ever since

Observations indicate that everything is moving away from everything else

Rapid expansion of all matter: Implies a common center for all matter

"The entire universe was compressed into a single infinitely dense point"

This point exploded 15 to 18 billion years ago

The Big Bang

Marks the beginning of the universe and the start of time

"no ordinary explosion"

"This explosion instantly created the universe. Matter, energy, space and even time came into existence with this single event."

 

Future of the Universe

One of two possibilities

1) Open Universe

The galaxies will continue to expand "forever"

All stars will eventually use up their fuel and burn out

Universe will then be cold and dead, forever

2) Closed Universe

The expansion will slow until the overall gravitation attraction of the matter will cause the universe to collapse (The Big Crunch)

This could lead to a new Big Bang, and new universe

Were there others in the past?

How long has this been going on, and how could we ever find out

Theoretical stuff like this is a lot like geology

Impossible to prove or disprove, so we are free to speculate all we want

 

Formation of the Solar System

Formed by the condensation of a "nebula"

Slowly rotating in space, and very cold (-270°C)

Gravitation attraction caused this matter to condense

Condensation resulted in faster rotation

The Law of Conservation of Angular Momentum

Most of the matter accumulated into the center

At some point the amount of matter was sufficient to set off nuclear reactions which cause stars to give off energy

Critical mass

At the same time, the planets were forming

The rotational velocity of the nebula increased as it condensed

Caused the nebula to flatten and extend into a disk-shaped form

The planets being formed within the relatively narrow disk arms

Aggregates of material coalesced into larger bodies

Changed from a large number of small pieces to a small number of large chunks

How long did it take for the planets to accumulate

The initial condensation may have happened quickly

But, it's still going on!

Meteorite impacts indicate continued accumulation

How large of pieces can we expect to impact the earth?