This is an attempt to clear up mis understandings and questions from a QI forum.

It is incorrect to state that quantum physics (QP) is a theory of the very small world and relativity physics(RP) is a theory of the very large.

Lets start with RP. RP arises from Equivalence Principles, which go back to Galileo Galilie. The basic idea is that there is no preferred, or special, place either in space or in time. In other words the laws of physics (LOP) which observer A can deduce from their point of view (POV) will be the same as the LOP which observer B can deduce from their POV, NO MATTER what the relationship is between A and B. Einstein's Special theory of relativity arises from thinking about this when A and B are moving at a constant speed relative to each other. The General theory of relativity arises from thinking about this when relative acceleration is introduced.

(The only maths needed to work out the special theory's implications including E=MC² is Pythogoras' theorem.(?))

Both relativity theories are universal - they apply everywhere, at all positions and speeds, and at all sizes. The maths equations make use of the speed of light, approximately 300,000 kilometres/second. This number (squared) is usually the denominator in a division. When an object is traveling at a small speed (such as the space shuttle and interplanatary craft) the equations of motion derived from RP result in the Newtonian equations, to a very very close approximation because of the division by C squared. It is so close that, with our current technology, Newton's equations can be used for conveniences sake only. So yes, Newton does not contribute any thing unique.

Relativity applies to all sizes, inclusing the very small, which is why it, sometimes, has to be used when doing the maths associated with quantum mechanics. This gets called 'Relativistic Quantum Mechanics'. The most commonly cited example is a type of particle that gets created in the Earth's upper atmosphere only making down to the ground due to relativistic effects.

Although we don't use relativity for space exploration both Special and General theories are used millions of times each day by GPS (Global Positioning System).

Now for Quantum Mechanics (QM). This theory arose from two sources. The first was from the study of heat. No one could produce maths equations that explanined the observed heat radiation. In desparation Planck (in about 1895) tried assumming that heat radiation was not continuous but came in discrete, indivisible packets. The maths worked! The second came from the observation of the electrical effects of light falling on metals. Einstein explained this (in 1905, his 'miracleous year') by use of discrete packets. Together these two strands led to QM and its strange and weird effects. Again, this theory applies to everywhere and every time. Its effects can be observed when looking at small things. RP loses its impact when speeds are low. In the same way QM effects on objects larger than an atom are so small that they do not need to be considered (usually, there are exceptions).

By the end of the 19th centuary two forces were recognised: gravity and electromagnetism. The study of QM and the internal structure of the atom led to the recognistion of the weak and strong nuclear forces whoose effects don't extend beyond the nucleus of the atom. It also led, by the 1970s, to the so called 'Standard' model of the bits and pieces that make up atoms (and thus everything). Prior work and this work resulted in a number of constants being needed to make the theories perform. The earliest of these was the gravitational constant. The values of these constants have to, and have been, found by experiment.

All this theortical progress has been verified by experiment (despite Einstein's objections). But there are two problems. First, both relativity and QM apply everywhere so one should be deducable from the other or there should be another theory from which both RP and QM can be derived. This is the first aim of a Theory of Everything (TOE). The second problem concerns the constants. A good theory would predict the values of these constants. The second aim of a TOE is that these constants should come out naturally from the theory. And the third requirement is that the four known forces can be united as four aspects of one force.

So far the gropings towards a TOE have all been mathematical ideas. Over the last 20 or 30 years none (M theory, string theory, branes) have shown great promise, nor have they been expeimentally test. (The latest (New Scientist Jan 20) may be testable but hasn't been given the thumbs up.)

Science being science a good TOE should lead to more questions. Nor will a TOE help in chemistry, life, love, or mind.