Page 86 - A Brief History of Time - Stephen Hawking

A Brief History of Time - Stephen Hawking... Chapter 11

Figure 11:4

Similarly, a single piece of string can divide into two strings. In string theories, what were previously thought of
as particles are now pictured as waves traveling down the string, like waves on a vibrating kite string. The
emission or absorption of one particle by another corresponds to the dividing or joining together of strings. For
example, the gravitational force of the sun on the earth was pictured in particle theories as being caused by the
emission of a graviton by a particle in the sun and its absorption by a particle in the earth Figure 11:5.

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