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These are simply the basics that are required for astronomy. Theoretical physics and the like is simply to much math to get into here and has nothing to do with the basics of astronomy.
Einstein's Special Theory of Relativity*
Einstein's Theory of Relativity*
Basic Algebra nesseccary for calculations
* Only very basic concepts here, see reading list if you're interested in a more deeper understanding of these very important and fascinating theories.
- These basic Ideas are nesseccary before we go on.
A hypothesis is an idea that can be proven or disproven though scientific methods. Ie., experiments, mathematical simulations and the like.
A Theory is a hypothesis that has been proven and can have it's results proven universally, ie., it 's an experiment that yields the same results everywhere and can be duplicated with the same results.
A Law(ie., Newton's law of Gravity) Is a theory that has stood up to experimental scrutiny, is proven universal( if I went to the moon, Newton's law of gravity would still apply, as proven by the apollo astronauts) and can be back up and built upon. Meaning, if I come along and say that fish can fly, Newton's laws would allow me to have a footing to which I can build my new theory upon. It's like 1+1=2, from this I could hypothesise 1+2=3. Even though 1+1=2 doesn't specifically state 1+2=3. Hopefully you see what I mean.
Now, some are going, what's the difference between a law and a theory. I'm going to give examples of each and try to show you.
I hypothesise that 1/5th of you have already clicked off this page.I would have to prove this one way or an other. And since it is provable, I can put counters ect on the page to see how far readers go , it is a hypothesis. Saying God likes ponytails can't be proven , so it is not a hypothesis.
A theory is a group of hypothesis' and laws that have been well proven to be true and descibe a wide range of phenomenon associated with a given topic. Einstein's theory of Relativity applies to a wide range of phenomenon down to the subatomic. Quantum Theory then takes over. But as far as the macroscopic world, Einstein's theory of Relativity fully and elagantly descibes everything. He builds on Newton's Laws and also on QED(quantum electrodynamics read Feyman's QED for explaination of this theory) as well as using his own hypothesis' that all interact and can be built upon and followed back to the other theories I've said above.
A law is a theory that has been proven universal ( Newton's Laws apply to martians, romulans , stars, barney, bob villa, greg brady, crow, tom, gypsy, mike, joel, you, me, the universe at large , and anything else you can think of.) and it is backed up by centuries of proof.
Hopefully this is straight now.Here we go into the basics of the above theories and laws to get you up and ready for my pathetic attempt at story telling.
Each planet moves about the sun in an orbit that is an ellipse, with the sun at one focus of the ellipse.
picture a hockey rink. you've got the goallies at either end. they aren't right at the end though. they are at either focus of the ellipse. Keppler's talking about the same thing. the planets don't orbit in simple circles. they follow the outer perimeter of the hockey rink while the sun is at one focus of the ellipse. the sun doesn't switch focus like the goalies do.
The straight line joining a planet and the sun sweeps out equal areas in space in equal intervals of time.
picture yourself as th goalie standing still at your net. you've got a stop watch. assuming wayne can skate with the same speed everywhere and doesn't vary it it all, ( the earth doesn't speed up and then slow down, it would suck if it did this), you begin clocking him. Now what you're looking at is the area he's dividing the rink into. Like slicing up a pizza, where he stops, where he starts ect. will make a "slice" of the rink. Think of him starting at the farthest end from you. After 30 seconds you see the amount he moved on the perimeter is miniscle, but at that distance from you there's a set area he "sliced" the rink into.A long thin slice of pizza. Now as he moves towrds you, the amount he moves along the perimeter is greater but the distance from you is smaller, but he still has "sliced" up the same area, just different dimensions. It's a more stockyer piece of pizza. When he's at the backboards, he moves the greatest amount along the perimeter in the given time frame but he's so close to you the sides of the slice have shrunk considerably. He's still "sliced" the rink up into the same sized area as before. If this isn't clear try this at home with a piece of string to make the oval, a glass to signify the goallie, a friend with a toy car as gretsky and yourself as yourself with a stop watch. measure from goalie glass to car, then have car move for set time(this never varies) then stop it and measure distance from glass and the legnth along the perimeter it moved. I assume you can multiply these to get the area. ( figure it a triangle-ish shape and 1/2 (base X height) gives you area. continue this all the way around at the same time intervals and you will see the areas of the triangles the car sweeps out are the same.
the squares of the planets' periods of revolution are in direct proportion to the cubes of the semimajor axes of there orbits.
the period is just how long it takes to make one complete trip of it's perimeter. like the earth's is one year. it's semi major axis is simply the radius of the ellipse from the center to it's farthest away point. like an egg has a point on it's side that's farther away from the center inside than any other point. it's the same thing. I'll show you with the earth so you can see what this means and one with saturn so you see it's copastetic.
earth's period = 1 year
earth's semimajor axes= 1 au
square 1 year = 1
cube semi major axes= 1
proportional is a fancy word for equal
saturn
period= 29.46
sma=9.538
square period=867.892
cube sma=867.7
Now other than a cute observation all this is saying is there's a relationship between how far away from the sun something is and how long it takes to orbit. there's a symmetry between where the planets are and how fast the orbit the sun. it's like the number pi (3.14) for circles, the ratio of any circles are to it's circumference is going to be identical simply because they're all circles, the ratio being pi. It's used for calculations and I put it in for completeness is all.
