Neal Adams, comic book artist of X men and Green Lantern comics back in the 60's and 70's, recently became a proponent of a growing earth theory when he saw that the continents, if cut out of a globe, all fit together into a perfect ball without any real adjustment to the shape of the original pieces. This led him to form a theory on how and why the earth could be growing. It was Adams' model on Youtube which led me to believe this same theory, however I disagree completely with Adams' hypothesis that pair production is causing new matter to form at the earth's core. I believe it is something much simpler.
Adams was not the originator of an expanding earth theory. It was first proposed by professor S. Warren Carey, an Australian geologist. Carey had set out in the 1940s and 50s to prove the validity of the theory of subduction, working with what basically was the concept of plate tectonics. His work was rejected as being foolish and naive. In time those very theories would become accepted as scientific fact. However, 20 years later in 1976, Carey published a book called Expanding Earth, comprising what he thought was a more "probable model". So keep in mind that the idea of an expanding earth was first theorized by one of the first people to suggest the commonly held belief of subduction today.
Wikipedia states in the entry on "expanding Earth" that
"The primary objections to expanding Earth center around the lack of an accepted process by which the Earth's radius could increase and on the fact that the Earth's radius is not measured to be increasing today."
I will get to my theory on how the earth could be expanding, but first, addressing the second complaint, that earth's radius has not been observed to be expanding, is ridiculous. The seafloor expanded over 170 million years. We have only been in a position to see and measure the earth from space for 40 years or so. This is like saying you watched your hair for an hour and didn't see it grow, therefore hair does not grow. Maps of the world which show the age of the various parts of the sea floor show that the ocean floor is not all the same age. In the Atlantic, it is oldest at the edges of the continents, and gets newest toward the center of the ocean along a rift line. The northern end of this rift line forms the cluster of Portuguese islands of Sao Jorge, Pico, Terceira, Graciosa, Faial, and Sao Miguel.
In the pacific, however, the newest floor is around the undersea rift line that runs aground and becomes the infamous San Andreas fault. this rift line runs straight south in the ocean, all the way to Antarctica. To the north, the rift is the continental shelf along the west coast of north America. It terminates as it runs into the armpit of Alaska.
Referring to the map provided by the National Geophysical Data Center, The age of the sea floor ranges from 180 million years (blue) to 9.7 million years (red). Further, the patchiness of the map appears to show that the sea floor did not grow gradually, but in stages where it grew steadily, and suddenly, then remained unchanged for millions of years, then grew again.
The oldest spot on the sea floor is within the sea of Okhotsk, between Russia and Japan. The sea is unusually deep, 2 miles deep at the center.
My hypothesis begins that before the expansion, the earth was 1/4 its current size, with the present continents forming its original outer crust. 'Crust' is a good word here, because if you look at a loaf of homemade bread, the outer crust is broken up and pushed apart as the bread within expands. This is what happened to the earth.
To really understand why the earth expanded we have to imagine how the earth itself formed, based on the best theories of current science. Scientists assume the planets of the solar system were all coalesced from debris from the sun's formation. So earth was formed from dust and rocks and metallic asteroids. So already science is on our side, admitting that the earth did not pop into existence at its current size, but was formed up from small pieces, and as its size increased, so did its gravity, and it and all the other planets eventually vacuumed up all the debris in their orbital vicinity.
Modern Science accepts the 'collision theory' as being the accepted origin story of the moon, that a mars-size planet collided with Earth, grazing it and leaving a saturn-like ring of debris orbiting around it. Some of this debris eventually formed the moon, and the rest of the debris would have fallen back to earth. Since the impact would have a catastrophic effect to the surface, we would have to assume that life would not have arrived on earth until after this event. Furthermore, because of the incredible heat released from such an event, It is unlikely that any water would remain on the surface for several million, if not billions of years. One quarter its original size, dry and lifeless, barely cooled to solidity by the cold vacuum of space, the surface burns with the heat of the molten rock beneath. But as soon as water WAS introduced to this geothermally heated, mineral rich environment, RNA was able to form randomly, which eventually became DNA and formed into the first single celled organisms. These processes would have begun as soon as water was introduced, and as soon as the atmosphere was able to sustain them. So if water is the main factor in the formation of life, it makes sense that water would be the catalyst for crustal expansion.
The general consensus is that earth acquired its ocean by attracting ice comets. These comets brought the first water to earth, covering what would now be dry land. Eventually the crust had cooled to a solid state, comprising a 45-60 mile thick shell floating on a molten surface. But there were rift points, cracks in the shell. These geothermal cracks broke the shell into puzzle pieces that became the continents. Thus water flowed into these cracks.
When lava would erupt, as it often does, from any point along these rift lines, the water would violently explode into steam, causing a cavitation of rock, sand, and steam. This expansion can be seen many places, like an overflowing bowl of oatmeal in the microwave, or pasta boiling over. Both occur because starch is entering the water, and its viscosity allows the bubbles to get much larger than normal water bubbles. The slurry of volcanic mud mixing with underwater steam is just as likely to react in a similar manner. Only when the volcanic activity ceases and the overflowing hot mass of molten rock mousse finally cools, it has expanded to three times its original volume. This expansion would occur as far downward into the earth as the rift extends, which is most likely the entire way to the mantle, about 4-5 miles down from the sea floor.
So the continents would have had much rounder surfaces originally, and as the seafloor became more and more vast, the continents, like inverted bowls, would have crumpled inward to accommodate the flattening surface as the circumference became greater. Further crumpling occurs from continued expansion at the sea floor. If you look at Google earth, at the Arabian peninsula/horn of Africa, there is a major rift extending from the Gulf of Aden, and extending out into the Indian ocean. This rift has obvious plow-like lines showing the direction of expansion, and if you compare the rift's length, direction and angle of expansion to the Himalayas, you can see that this rift, which expanded most recently about 9 million years ago, completely matches the angle and length of the famous mountain range.It would appear that this rift, and its expansion, is what is causing the Himalayas to grow.
This theory of crustal expansion seems to assert that subduction is not occurring. While I think it's possible that there can be some subduction zones where the new ocean floor material is bunching up and being forced into a downward wrinkle, it's not possible for crustal material to "sink" into magma, because magma is twice as dense as granitic rock. This would be like waiting for styrofoam to sink into water.