The overall book provides an understanding to lay readers of effects across apparently empty space--electromagnetism, gravity and inertia. The extended magnetism edition continues with additional text and graphics to provide a more complete understanding of magnetism, especially permanent magnetism, in the same clear, concise essentially non-mathematical style as the original book.
The following supplements this with an abbreviated discussion of Einstein's concept of mass distorting time from Nigel Calder's outstanding book Einstein's Universe. Before I read it, I had to accept that mass distorts time, but had no intuitive understanding of it. Calder's inspired use of his light bubble concept with black holes offers an outstanding intuitive understanding of the concept of how mass distorts time.
Briefly stated: a light-bubble is a region of space expanding at the speed of light that contains all possible futures an object can have; a black hole is a region of space within which gravity is so intense that light can't escape from it. All possible futures for objects within light-bubbles lie toward the light-bubble centers.
1.The centers of light-bubbles can be displaced by nearby mass.
2.If the mass displacing the center of a light bubble circles, the space within the light bubble will circle
3.Time stops at the outer edge of black holes.
4.Time slows within black holes as their outer edges are approached.
That's essentially it.
It is intuitively apparent that, if light has mass, which Einstein's theory asserts, then sufficient gravity can stop light in its tracks, forming what is called a black hole from which even light can't escape.
Effectively, time stands still at the outer edge of a black hole-nothing can move beyond it-and as something approaches the outer edge closer and closer, the measurement of time there will pass slower and slower. Then the rate measured by atomic clocks is less and less and the frequency of any light becomes less and less-that is, any light shifts to lower frequencies which is to say it reddens. This effect is called the gravity red-shift or the einstein red-shift. The energy has lessened.
If a lamp aboard any platform nearing the edge of a black hole is blinking, its blink rate lessens accordingly by the same reasoning.It is apparent from all this, that any mass will affect the measurement of time within its vicinity.

A quote from a five-star rated review for the original book: "Insightful and well written, this was a surprisingly interesting read. I would recommend that all seekers of knowledge take the time to read this."
About the Author: The author has 34 years experience in electronic engineering and design. He is listed in Who's Who in America and Who's Who in Science and Engineering