Fundamentals of Light and Matter
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The document discusses the fundamentals of matter and energy, explaining that matter is the substance of physical objects, composed of atoms that contain protons, neutrons, and electrons. It describes different states of matter, types of energy, and the principles of energy conservation, including nuclear fission and fusion. Additionally, it briefly covers the nature of light and its relevance in astronomical observations.
Fundamentals of Light and Matter
- 1. Sciencey Stuff Fundamentals: Light and Matter Dr. Johnson
- 2. What is matter? * Not to be confused with Whatsamatta – the university Bullwinkle attended
- 3. Matter is the “stuff” that makes up our “things”
- 4. The nucleus of an atom is composed of protons and neutrons (nucleons) Nucleons are ‘Baryonic Matter’ which means they are composed of smaller things called quarks
- 5. An atom will have a certain number of protons and neutrons (usually close to the same number) The number of protons tells you which element you have
- 6. Atoms with the same number of protons, but different numbers of neutrons are called ISOTOPES Isotopes will have different masses and nuclear properties Some isotopes are more common in nature
- 7. Atoms also have electrons (usually) Electrons have a negative charge & protons have a positive charge Neutrons have no charge When you have the same number of protons and neutrons the atom has no net charge, it is neutral Otherwise, the atom a positive or negative charge
- 8. Atoms share electrons to form molecules This is chemistry! *we won’t talk much about chemistry Water Vinegar
- 9. Like Legos, atoms and molecules join together to form bigger and bigger compounds
- 10. They eventually form things like Rocks & Chairs
- 11. What distinguishes matter from energy? It has: Occupies Volume
- 12. There are also other (non-baryonic) kinds of matter including bosons and leptons Notice that electrons are leptons This means they are point particles not made up of quarks
- 13. There are four states of matter Can you name them? Their state depends on how much kinetic energy they have •Solid •Liquid •Gas •Plasma
- 14. The more kinetic energy or motion they have, the higher the temperature we measure
- 15. What is energy? Nucleons are ‘Baryonic Matter’ which means they are composed of smaller things called quarks •Kinetic (motion) •Potential •Radiative
- 16. Kinetic Energy The energy of motion Mass and speed are important!
- 17. Potential Energy The energy you have due to your location (in a gravitational field) or which you may have stored up (chemical) Mass and position are important!
- 18. Radiative Energy Electromagnetic Energy (light) Atoms have set energy levels where electrons can live If atoms absorb the right energy in a packet of light (photon) an electron can move to a higher more energetic level, and when and electron gives up energy it drops down to a lower energy level
- 19. Energy and Matter ‘can’ transform! In the right conditions, such as at the dense core of a star with very high temperatures, it can be a 2-way street E = mc2 Thanks, Einstein!
- 20. The Law of Conservation of Energy In a closed system (like the Universe) energy or matter cannot be created or destroyed, only transformed
- 23. Nuclear Energy Nuclear Fission: Heavy nuclei are unstable, and over some period of time they will decay into lighter elements and emit radiation Nuclear Fusion: Light nuclei in hot/dense conditions, like the core of a star may move fast enough to bind together with the Strong Force and form a heavier element
- 24. Light (electromagnetic energy) Light can be considered as a particle (photo) and a wave Light is the propagation of electric and magnetic fields The distance from one peak to the next is called a wavelength
- 26. Understanding light allows astronomers to be detectives and from a huge distance tell: *But that’s another lecture for another day because I fear we are out of time… Don’t get me started on time, that would take at least several lectures…. • A star’s surface temperature by peak wavelength (color) • A star’s chemical composition by spectral analysis • A star’s radial velocity from Doppler shifts
- 27. May the F=ma be with you!