M-Theory

We now have a candidate for the ultimate theory of everything as M-theory.

M-theory is:

• the only model that has all the properties we think the final theory should have
• a whole family of different theories, each of which is a good description of observations only in some range of physical situations
• like a map

This book is based on M-Theory.

The earth’s surface cannot be shown on a single map. The usual Mercator projection used for maps of the world:

• makes areas appear larger in the far north and south
• doesn’t cover the North and South Poles.

To faithfully map the entire earth, one has to use a collection of maps, each of which covers a limited region.

• The maps overlap each other, and where they do, they show the same landscape.

M-theory is similar.

The different theories in the M-theory family may look very different, but they can all be regarded as aspects of the same underlying theory.

They are versions of the theory that are applicable only in limited ranges as when energy is small.

Like the overlapping maps in a Mercator projection, where the ranges of different versions overlap, they predict the same phenomena.

There is no flat map to represent the earth’s entire surface.

• There is also no single theory to represent observations in all situations.

According to M-theory, ours is not the only universe.

• There are many universes created out of nothing.*

These multiple universes arise naturally from physical law.

Each universe has many possible histories and many possible states at later times, that is, at times like the present, long after their creation.

Most of these states will be:

• unlike our universe
• unsuitable for the existence of life.

Only a very few would allow creatures like us to exist.

Thus we select only those universes that are compatible with our existence. Although we are puny and insignificant on the scale of the cosmos, this makes us in a sense the lords of creation. *