|
1917. Dominant Theory: The Universe is static – constant in size with relative positions of galaxies unchanging.
Predictions: When the wavelengths of the light from star cluster X is measured, you will find wavelengths ABC.
Data: The wavelengths from star cluster X were not ABC.
When scientists analyzed the wavelengths of light received from stars, these wavelengths were longer than expected (shifted towards the “red” end of the spectrum), and the farther away a galaxy is from earth the greater is the shift from the expected norm.
Conclusion: Most scientists regarded the Static Universe theory as having been refuted, but probably only because they could see the data as evidence for an expanding universe. If they didn’t have an alternative in mind, they probably would have stuck with the static model and worked on it. Some in fact did stick with the static model. Were they being poor scientists?
Issues:
Why is the data considered to be "data"? How do we get from raw sensory experience to measuring wavelengths of star light?
How can we deduce this prediction, or any prediction from such a simply stated theory?
Morals of the story:
New theory: the universe is expanding. But why and how? Need more details in order to get new predictions. So new theories were developed that were specific enough to produce predictions of concrete observable events.
Two important Rivals.
Data: Decreasing density of matter the farther out one looks from earth.
Most cosmologists began working on the Big Bang Theory. But not all. Some tried to repair the Steady State theory. Others developed alternatives to the Big Bang.
Fill in more details of the model, using accepted theories from other areas of physics.
New prediction: Should "observe" a uniform background radiation throughout the entire universe of about 3 K.
1965 – Data: The uniform background radiation at 3 K was "observed".
"This data is taken by most cosmologists as solid proof of the Hot Big Bang theory".