1. Einstein’s Big Idea Nature of Science What do scientists do? How are scientific ideas developed? Why do we believe them? What is a theory in science? How is this different from how most people think about the word? How is this different from say journalism or religion? What is a scientific statement? Slide 20-3

2. Einstein’s Big Idea Nature of Science What do scientists do? How are scientific ideas developed? Why do we believe them? What is a theory in science? How is this different from how most people think about the word? How is this different from say journalism or religion? What does E = mc 2 mean? Can you explain it to your grandmother? Slide 20-3

3. A Quick Tour of the Universe (and this course)

5. Cassiopeia A: Supernova Remnant

6. Example Supernova: 1998bw

7. A Young Supernova SN 1993J Rupen et al.

11. 1 kpc

15. Cosmic Microwave Background

16. Scales of the Universe Powers of 10 film What conclusions can you draw from this film

17. Scales of your world

18. Scales of the Universe

19. Foundations of Astronomy The Metric System (used by scientists and foreigners) Mass 1 kilogram (kg) = 1000 grams (g) 28 g = 1 ounce If your mass is 220 lbs, it's also 100 kg. We tend to use mass and weight interchangeably, but weight depends on gravity.

20. Distance 1 meter (m) = 100 centimeters (cm) = 39.4 inches (slightly longer than a yard - your professor is 1.8 m in height) 1 cm = 0.39 inches Volume 1 cubic centimeter or 1 cm 3 = 0.06 cubic inches (about the size of a sugar cube)

21. Density Density = Mass (g / cm 3 ) Volume Densities of Common Substances Balsa Wood 0.13 g / cm 3 Oak 0.7 Gasoline 0.7 Plastic ~1.0 Water 1.0 Average Rock 2.4 Iron 7.9 Lead 11.3 Gold 19.3

22. Temperature The Celsius Scale: T( o C ) = 5/9 [ T( o F) - 32 o F ] so 32 o F = 0 o C 212 o F = 100 o C 68 o F = 20 o C The Kelvin Scale: T(K) = T( o C) + 273 o C "Absolute zero" 0 K = -273 o C

23. Angular Measure 90 o 20 o 360 o, or 360 degrees, in a circle. 1 o = 60' or arcminutes 1' = 60" or arcseconds 1" = 1000 mas or milli-arcseconds