Getting here late so I'll just provide a sort of stream of conciousness type response.
Undertaker #59 on 10-20-2006 at 12:38 PM said:
I think Einstein's theory is more of an expansion of Newton's original law. General relativity unifies special relativity and Newton's law of universal gravitation with the insight that gravitation is not due to a force but rather is a manifestation of curved space and time, this curvature being produced by the mass-energy and momentum content of the spacetime. So yes, from my understanding, Newton's equations do not work as well on as grand a scale.
Actually GR is related to SR in only an indirect way.
SR is limited to "inertial reference frames", that is it only applies to situations with constant velocity. It explicitly avoids cases where acceleration occurs.
GR addresses the situation when one has acceleration.
Einstein postulated that there was no difference between the mass used in Newton's laws of motion (inertial mass) and mass used in Newton's law of gravity.
Believe it or not, this assumption has profound implications.
Consider the following hypothetical.
Suppose you are in a room on earth and you have any possible set of experimental equipment to measure the weight of an object (gravitational mass).
Now suppose you are in a space ship far far away from any planet or sun (i.e. "weightless") and the ship is accelerating at a constant 1G. You have the same set of experimental equipment as the room on earth.
What will the two set of experiments measure?
The exact same thing, in fact it is not possible to tell the difference between the two setups by any experiment you could perform inside that room, you can only tell by looking out the window.
If you can so easily mimic gravity by the proper type of motion, maybe the idea of a "force of gravity" isn't true and is actually due to some other sort of motion.
This line of reasoning lead to the curved space-time model for gravity.
And to be clear, the breakdown of Newtonian gravity is not at large scales, but in strong gravitational fields, or highly curved space-time in the Einsteinian model.
The problem with GR at the quantum scale, is that curvature of space-time at that scale doesn't work well (mathematically).
To explain why two separate analogies are effective.
At a sufficiently small scale, space-time is thought to not be continuous. That is, instead of the solid rubber sheet that is seen to stretch in most of the GR examples, you have a "foam" that won't stretch smoothly.
The other one is that the amount of curvature increases as you get closer to the "surface" of the particle/object. At the micro scale, those distances get smaller and smaller and eventually become infinitely small, thus infinitely curved.
This is in fact one of the major advantages in the String theory and it's offshoots (M theory, D-branes, etc.) is that it avoids this particular source of infinities in calculations.
In "standard" quantum mechanics, each of the fundamental particles are point objects. By definition, a point has no physical extent in any direction. Therefore it is possible for these particles to interact at virtually zero distance. All of the equations that describe these interactions involved something similar to the 1/r^2 relationship in Newtonian gravity.
Thus you end up dividing by zero and get an infinite result.
The string theory postulates that the fundamental particles are one dimensional strings. They are so short that they appear like a point, but the fact that they have a very very small, but finite, size means they can't be at zero distance, thus the infinities go away.
As far as being able to conduct experiments to prove or disprove the theory, that is primarily a limit of energy.
It requires an amount of energy far beyond any particle accelerator to directly test the present theories, however, quantum mechanics faced the same problem in its early years, so there is reason to think that someone will figure out a way to do a low energy test some day.
Oh, and who ever mentioned the Giraffe, repeated a common misconception on why it has a long neck.
The neck is long not to allow it to get more food, but to allow it to drink.
The Giraffe is one of a few animals that has longer front legs than back legs. That configuration allows the animal to run faster using less energy. However, it does pose a problem on how to get a drink.
If the neck stays the same length, you would have to kneel or lie down to get your head to the water. Clearly not a great idea with lions or other predators hanging around the water hole. Thus the long neck.
With regards to the question on religion and violence.
I don't think religion is any different than any other "-ism" out there in terms of being responsible for war, death and destruction.
Nationalism, Communism, Nazism, racism, etc. all share the same common element with the worst examples of any religious based -ism.
They all form a way of some leader to combine a group of people together, to separate "them" from "us". The fact that these leaders often use violence against the "them" says more about the nature of man, and those individual leaders, than it does about any particular "-ism".
I don't agree that if one eliminated any individual "-ism" from the list you would have altered human history significantly, because there is always another "-ism" to substitute and achieve the same tragedies.
As far as belief in a religion, humans use a whole host of methods to help them deal with the unknowns and tragedies in life. Some use religion, some use psychotherapy, some use sports. There are hundreds of different methods used by people for this.
If that particular trick works for you, who am I to say you cannot use it. This of course assumes that your method does not clearly impact the rights of others. For example if your trick is to torture other people to death, that isn't something that would be allowed.
I do not think you have the right to make me use your method, but by the same token I do not have the right to prevent you from using yours.
