Chapter 3 is entitled “The Expanding Universe.” Here are a few things I learned from it:
- it is projected that there are 100,000 million galaxies in the universe, each with 100,000 million stars (37).
- the color of light is the only observable aspect of distant starts, and temperature is measured by spectrum of light (37).
- the SPECTRA OF LIGHT that have shifted toward the red-end of the spectrum indicates a star is moving away, a SPECTRA-BLUE SHIFTED star indictes it is moving closer to us. most galaxies are SPECTRA-RED SHIFTED; therefore most galaxies are moving away; therefore the universe is expanding (39). Also all galaxies are moving directly away from each other, and speed is proportional to distance between galaxies (42).
- The DOPPLER EFFECT is the relationship between frequency and speed: BLUE light has a higher frequency and moves faster than RED light that has a lower frequency and moves slower (38-39).
- Einstein’s COSMOLOGICAL CONSTANT is an ANTI-GRAVITYforce that balances gravity in a tendancy toward stasis (40).
- The universe is the same in all directions. Interesting! (40).
- Apparently “Gravity is so strong that space is bent around onto itself, making it rather like the surface of the earth” (44). Therefore the universe is finite in extent. Hawking gives this to clarify: “The idea that one could go right round the universe and end up where one started makes good science fiction, but it doesn’t have much practical significance, because it can be shown that the universe would recollapse to zero size before one could get round” (44). A problem I have with this is that in Chapter 2, Hawking said that gravity doesn’t control the orbits of the planets/solar bodies, but rather it they follow a GEODESIC. Perhaps GRAVITY holds the universe itself together, while the orbits are held in place by the GEODESICS. Perhaps I do not fully understand the dynamics between GRAVITY and GEODESICS in the universe quite yet.
- The universe is expanding “by between 5-10% ever thousand million years” (45).
- DARK MATTER cannot be seen directly but “the influence of its gravitational attraction on the orbits of stars in the galaxies” can be “felt,” so to speak (45). Though I don’t know exactly what DARK MATTER is yet.
- There is talk about the BIG BANG THEORY and how TIME began at the BB because EVENTS that occured beforehand had no consequence (46).
- The STEADY STATE THEORY states that as galaxies move away, new ones are forming in their place; therefore the universe always appears the roughly the same (47). That seems illogical because if the universe is ever-expanding and ever-producing new galaxies, then it would never look the same because things were “constantly” moving, growing, shifting, etc.
- a BLACK HOLE is a star that collapses to zero size and zero volume (49). How, I don’t know.
Chapter 4 is entitled “The Uncertainty Principle.” Here are a few things I learned from it:
- SCIENTIFIC DETERMINISM means that if you know the complete state of the universe at any given time, you can predict anything that will happen in the universe (53). Certain early 19th century scientists believed in this doctrine.
- a QUANTA is a packet of waves emitted from a HOT BODY; a QUANTUM is one wave emitted (54).
- German Scientist, Max Planck (~1900) determined that rather than the idea that all HOT BODIES radiate an infinite amount of energy (54), due to the finite capacity to hold energy in a QUANTUM (due to high frequencies), the radiation lost from a HOT BODY would be finite (54). This has to do with being able to measure velocity and frequency of energy. Hold on…hopefully it will make more sense in a second (maybe not!).
- Around 1926, another German scientist, Werner Heisenberg, came up with the UNCERTAINTY PRINCIPLE, which stated that “in order to predict the future position and velocity of a particle, one has to be able to measure its present position and velocity accurately” (54). Now, this takes into consideration the earlier-mentioned idea of SCIENTIFIC DETERMINISM, that measuring the “now” can help predict the “future” of the universe, etc. Well, what Heisenberg determined was that “the more accurately you try to measure the position of the particle, the less accurately you can measure its speed, and vice versa” (55). Therefore, you can’t measure the present state of things accurately.
- QUANTUM MECHANICS is “based on the UNCERTAINTY PRINCIPLE,” and a QUANTUM STATE considers the “combination of position and velocity” (55).
- QUANTUM MECHANICS is POSSIBILISTIC and doesn’t predict a single, definite result from an observation (55). QUANTUM MECHANICS deals with randomness and chance (56).
- According to QUANTUM MECHANICS, Particle A reaches Particle B by every possible path, not just by a straight line or a single path(60).
- All is predictable in QUANTUM MECHANICS provided the UNCERTAINTY PRINCPLE sets the limits (60).
I think the idea of QUANTUM MECHANICS is an interesting one. It definitely lends much to the idea that certainty in our measurements or interpretation of the universe is up for debate. Being left with the POSSIBILISTIC is always a good thing!