Newtons first Law; Objects will remain at rest or in uniform motion [that is neither accelerated nor braked], unless acted upon by an external force.
Newtons 3rd Law. A force always has an equal and opposite reacting force. A system cannot be affected by forces and reactions within itself. Moving your finger on the mouse or expoding a 50,000lb bomb have exactly the same effect on Earth's motion in the Universe, ie absolutely none. An analogy, [we're good at those here!] would be the good old tried-and tested "lift yourself off the ground by your bootstraps". It don't woik!! Earth has been in near enough the same orbit for around 4,000,000,000 years, and to change its orbit relative to the Sun requires, effectively, the gain or loss of mass to provide the necessary force. A meteorite will do it, as will lauching a Shuttle, but as F = ma,[ force = mass x acceleration, Newtons 2nd Law], the effects are very, very small indeed given the Earth's enormous mass.
PS ADDED.
The Earths spin, (as opposed to its orbit) can be changed by actions on the surface, ie. by a car accelerating east to west. The effect is nullified when the car is braked to rest again. The Moon has the greatest slowing effect, due to tides, and the days are getting longer. Very slow change to be sure, but its estimated that when Tyrannosaurus Rex roamed our flourishing green planet, a day was about 20 hours, ie a loss of 4 hours in 70 million years. Boy, it musta been a-spinnin' at first!
Radar, you are on to something here! The "Scotch on the rocks diet!" Eureka! May I suggest a good Malt, as opposed to grain whisky, or a good Bourbon. My favorites are Jack Daniels, The Macallan, 12yrs, or The Balvenie Single Barrel, 15 years, or there's Glenmorangie, Glenfiddich etc. etc. Nectar of the Gods, and we haven't mentioned Irish Whiskey yet!
'Course we'd need to do proper scientific tests, ( notice suddenly it's "we"!! ), it could take years to try all the brands to see if there's any difference, given the limits of sensible drinking, but someone's got to do it! A Government Grant perhaps?- they've been given for far more mundane projects than this by far, and we urgently need get the citizens less obese, don't we?
Alan
[This message has been edited by Alan Belson (edited 01-28-2006).]
