What causes gravity? How does gravity work? We were all taught at school that gravity is caused by an attraction which exists between all objects. But why do these objects attract each other and how do they do it?

An examination of the writings of Leonhard Euler shows that he dissented as to the cause of gravity. He showed that if an object moved that it must be because of a force external to the object. Objects can not propel themselves forward - something else outside of them must be doing the pushing. And so Euler defined gravity as a pressure which came from outside objects. In recent years, a famous American astronomer, Dr Tom Van Flandern has revived this line of thinking and has written much about it. He liked my Euler research so much that he asked me to write about it for his own journal. Van Flandern has been able to define some of the properties of gravity. For example, he points out that Newtonian gravity actually violates Einstein's General Theory of Relativity. When scientists do gravity calculations they assume that gravity propagates itself instantaneously across the solar system. This is absolutely necessary because otherwise the gravity calculations don't work. This means that Newtonian gravity can only work if it propagates itself at faster than the speed of light - which is a violation of Einstein's General Theory of Relativity. Van Flandern explained how gravity might be caused by a type of particle which propagates at faster-than-light-speed which then has a mean free path many times greater than the solar system. In other words, the particles which cause gravity actually begin to behave like a gas but only at distances greater than those present inside the Solar System.

Another astronomer wrote a paper in the 1960's where he pointed out that gravity might actually not be valid at galactic distances. For example it has been found that the outer sections of the long arms of spiral galaxies actually move faster than the inner sections. This means that spiral galaxies violate Newtonian gravity.

In the 1970's one laboratory showed that gravity broke down at distances of less than one foot. It conducted highly sophisticated experiments into the matter and the results were reported in the prestigious journal: Nature.

All engineering formulae are only valid for a certain range of values. All formulae break down above and below certain values. So why not gravity? Do we really know enough about gravity to assume that it is valid for all ranges of values? Could it be that it is only valid for distances matching those found in the Solar System? Newtonian gravity is well-tested among the planets, but is it valid for distances and conditions inside planets?

Albert Einstein suggested to Dr E. Saxl in the 1950's that perhaps gravity was affected by electricity. Saxl then devised an electric pendulum with which he performed experiments for the next 17 years at Harvard University. Saxl's discoveries were bizarre. He found gravity exhibiting strange patterns. Some scientists have suggested that his experiments may have been flawed, but I'm not sure I agree. Strictly speaking therefore, all gravity experiments have always been conducted in an electrically neutral environment and to the present day no scientists have truly explored the link between gravity and electricity.

Ron Kotas is a microwave engineer who has been researching his Nuclear Quantum Theory of Gravity (c) for the past 30 years. Kotas believes gravity can be explained by radiations' which occur at the atomic level. One of Kotas' revelations is that electricity must affect gravity - just as Einstein thought. Given the conditions inside the Earth where there are electric currents, Kotas shows that electric currents running in parallel would intensify gravity. The implications of this for the Hollow Earth theory is that the Earth's mass might actually be less than we believe it to be because there are electric currents of about 1 billion amps deep inside the Earth.

I go on to examine mine, seabed and borehole experiments which show that Newton's universal constant, G, actually varies with depth and actually increases the deeper the experiments are conducted. These experiments were reported by Australian scientists who were investigating the Fifth Force. Again, the implication is that less mass can produce more attractive force - ergo, the Earth may be lighter than we suppose.

When all factors are taken into account we begin to see the researches of many showing that gravity is a dynamic force which is poorly understood and which may be very complex. This takes us a far cry from the current view of gravity being a static force. It may be that the Earth is hollow and we do not even know about it because electric currents running inside the Earth might be increasing the attractive force of matter.