Is the earth expanding? 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]
 A: 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.
A: 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.
A: 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
A: 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.
A: There are several indicators that the Earth is both Growing ( increasing Mass ),
and Expanding ( increasing volume with or without mass increase ).
1) The continents and the submerged continental fragments fit together
on all the sides simultaneously at a radius of  between 53.88 % R of the current 
radius ( excluding the fragments ), up to about 58.5% R ( including all the
submerged fragments ). This simultaneous adjoining of all the continents
occurred up through the end of the Permian, when one of more bad events
started the next wave of growth and expansion.  The end of the Permian
was associated with a 120 meter world wide drop in sea levels. The Reefs
that formed during the Permian are now 4,000 to 8,000 feet or more above the 
current sea levels.  Some other older Reefs are at still higher elevations,
like the Reef in the middle of the Salar de Uyuni in Bolivia. ( Unified Salt ).
The Dinosaurs were not physically possible in the current surface gravity
of the Earth, but they had no problem in the surface gravity of the times
that they lived in.  You might note that Dinosaur sizes, and later on,
Mammal sizes diminished with the passage of time.  The Math Theory here is
that the surface gravity of the Earth was/is inversely proportional to the
cube root of the dinosaur mass expressed as equivalent Male African
Elephant volumes.  So when the biggest dinosaurs reduced in size to
be only 8 Elephant Volumes, then the cube root of 8 = 2, and inverting
gives a value of 1/2 g ( now ). The trouble is the When ????  How many
Million years ago did this occur?  The maximum size should be less than
13 Elephant volumes for the largest sized dinosaur with a lowest gravity
being greater than 0.425 g ( now ).
