1. Warm-up:
1. According to your calculations, what is the age of the universe?
2. What is Hubble’s Law?
3. Why do you think it’s called Hubble’s LAW and not Hubble’s THEORY?

2. Today’s Notes: Topic: The Big Bang Theory
Essential Question: What is the difference between a theory and a law?

3. Hubble’s LAW vs. The Big Bang THEORY
Is it based on tested hypotheses?
Is it widely accepted by the vast majority (if not all) scientists within a discipline?
Is it possible to prove it wrong at some time if there are data to suggest it is?
Is it supported by a large body of evidence?

4. Evidence What evidence do we have for the Big Bang Theory?
What evidence do we have for Hubble’s Law?
What evidence do we have for the Big Bang Theory?

5. Cosmic Background Radiation
The speed of light is 3 X 10^8 m/s
The sun is about 1.5 X 10^11 meters from Earth.
How long does it take light to get from the Sun to the Earth?
When we look at the sun, we are looking back in time by about 8 min.

6. Cosmic Background Radiation
So according to the big bang theory, if we look far enough away, shouldn’t we be able to SEE the big bang?
According to the big bang theory, where should we look?
According to Hubble’s Law, what will it look like?

7. The universe 300,000 years after the big bang.

9. Cosmic Background Radiation
In 1965 radio astronomers Penzias and Wilson were trying to measure the radio ‘noise’ of the galactic halo.
They kept finding an annoying, weak excess noise
The signal was consistent with a radiation from a thermal source at 3° K.
They had accidentally discovered The microwave radiation that fills all space and is evidence of a hot Big Bang.
A paper had just been written (but not yet published) predicting exactly this radio noise from the big bang.
Penzias & Wilson won the Nobel Prize for this discovery in 1978

10. Warm-up:
List two pieces of evidence supporting the big bang theory.

11. So what’s the DIFFERENCE between a theory and a law?
LAW: generalizes all your observations into a simple, universal statement of fact. Can usually be expressed as a mathematical equation.
Examples?

12. So what’s the DIFFERENCE between a theory and a law?
THEORY: A theory is an explanation of a set of related observations or events based upon proven hypotheses and verified multiple times by detached groups of researchers.
Short answer: A Law tells you what happens, and a theory tells you WHY it happens.

13. Example: (http://wilstar.com/theories.htm)
A scientific law is like a slingshot. A slingshot has but one moving part--the rubber band. If you put a rock in it and draw it back, the rock will fly out at a predictable speed, depending upon the distance the band is drawn back.
An automobile has many moving parts, all working in unison to perform the chore of transporting someone from one point to another point. An automobile is a complex piece of machinery. Sometimes, improvements are made to one or more component parts. A new set of spark plugs that are composed of a better alloy that can withstand heat better, for example, might replace the existing set. But the function of the automobile as a whole remains unchanged.
A theory is like the automobile. Components of it can be changed or improved upon, without changing the overall truth of the theory as a whole.

14. Review: Make a Poster
What does the Big Bang Theory say? (What was it? What happened? When? What’s happening now?)
Prove it! (Evidence)
Hubble’s Law (explain how you proved Hubble’s Law)
Cosmic Background Radiation
Why is it more than “just a theory?”

15. Warm-up: Today you will finish your big bang theory posters:
1. Who is this poster for?
2. Why do you need to make a poster for him/her/them?
3. How does this poster help YOU?

16. Warm-up:
What information from your poster are you the LEAST confident about?
Take your warm-up page out, I will pick it up.

17. Things to watch out for:
On one question, I used the word “explained” when I meant to say “expanded”