Is the earth expanding?

Question

I recently saw this video on youtube:

http://www.youtube.com/watch?v=oJfBSc6e7QQ

and I don't know what to make of it. It seems as if the theory has enough evidence to be correct but where would all the water have appeared from? Would that much water have appeared over 60 million years? Also what would cause it to expand. The video suggests that since the time of dinosaurs the earths size has doubled in volume, how much of this is and can be true?

[could someone please tag this, I don't know what category this should come under]

Answer 1

It's not that the earth is expanding; instead the primary effect is that the earth's surface is shrinking. The effect occurs because the earth's surface doesn't remain flat. Instead, it gets tilted and folded. Some parts of the crust get subducted; once they disappear, what's left appears smaller.

Over any appreciable distance, rock has good compressive strength but negligible tensile strength. Consequently, when rock is pushed together it becomes thicker and taller (thereby decreasing the surface area; see the demonstration here: http://en.wikipedia.org/wiki/Mountain_building ). But when rock is pulled apart it instead tends to form cracks that are obviously new crust (and so are not counted when trying to determine if the earth's surface is expanding).

The overall effect is that the size of the older portion of the earth's surface is smaller than the actual current surface of the earth but this is only an effect of standard geology.

Answer 2

The "growing planet" hypothesis has two major, fundamental problems with it - one regarding its explanatory power, and the other more serious one regarding basic planetary physics

Firstly Everything in the video is fully explainable using non-growing plate tectonic theories. Why are old fish fossils on land? Because plate tectonics moved the plates around, changing sea levels mean some areas that were underwater now aren't. Why are the sea beds geologically so young? Because the plate movements keep recycling. Why does Mars not show signs of subduction? Because it's plates stopped moving around 3.5 billion years ago.

In fact, since most of the Martian surface is about 3-3.5 billion years old this presents real problems for the "growing planet" hypothesis (though not as major as item 2!) Did Mars stop growing? Why? According to standard geology the planet radiated away the heat required to drive its tectonic activity. The growing planet hypothesis has - as far as I can tell - nothing.

Secondly he fundamental physics behind the problem don't add up. Let's do some simple maths.

The growing earth hypothesis suggests that as recently as 60-100 million years ago, the planet was entirely land and has expanded to create the oceans.

The surface area of the planet is approximately 1 part in 3 land. This means that 100 million years ago the surface area of the planet was one third the area it is now. This means the radius of the planet was smaller by a factor of sqrt(3) (~1.7 times smaller). The volume of the earth would have been 5.2 times smaller (3^(3/2)).

The proponent of this hypothesis insists that the DENSITY stayed the same during this period - the mass of the Earth would have been 5.2 times smaller 100 million years ago! Given the mass of the Earth this comes out as a rate of change of mass averaging 1.5 billion kg/s! That's approximately one 50m asteroid strike per second (we're talking Tunguska event sized impacts here...)

Clearly ridiculous.

If the mass stays the same we're left with very uncomfortable problems from pressure. Isobaric compression to that volume would leave the mantle at the surface at around 4000 degrees Celsius (7300 degrees Fahrenheit). Enough to melt the crust.

Answer 3

Although considered a viable alternative hypothesis in the past, the expanding earth hypothesis is now generally considered to be obsolete, given the overwhelming evidence in support of plate tectonics. The following paper uses geologic evidence and a classical physical analysis of the earth-moon system to show there is no evidence that the earth's radius has significantly changed for at least the last ~620 Ma.

Williams, G.E. (2000), "Geological constraints on the Precambrian history of the Earth’s rotation and the moon’s orbit" (PDF), Reviews of Geophysics 38 (1): 37–59

Answer 4

I don't know as a fact if the earth is expanding or not. But way is it so hard to believe it is. On the same principal that ice expands when it mixes whit gases. Lava expands when it cools specialty when water is present. It fells whit gas bobbles and increases in volume 3 fold. On the same principal way is it not possible for the earth crust to expand. I'm not saying that the earth mass is increasing just the volume.