Expanding Earth Theory

[athon]

I've come across this a couple of times now, and it seems more ludicrous each time I hear it.

The Earth was once much smaller than it is today, apparently. Here, I'll let them explain it:

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

Athon

[sago]

From the vid: "This is so obvious that a child could see it"

And I spent 15 minutes this afternoon watching my son try to fit a round block in a square hole because he'd just successfully got the square block to fit there...

"For every complex problem there is a simple solution that is simple, neat and wrong."

[athon]

How dare you oppress your son! Afterall, not putting square blocks into round holes is a science conspiracy. That's right - scientists are afraid of the truth that would be unleashed if round holes could be plugged with square pegs. All of science would be undone!

This amazes me, I must admit. People who feel that their 'simple' discovery is enough to shake the foundations of centuries old observations. They don't stop to wonder - is it more likely that they've misunderstood something, or that thousands of other scientists have stuffed up? Especially with golden comments like 'the mantle is more dense than granite, therefore subduction can't occur'. Density has little to do with it, given the mantle is a liquid!

Gah!

Athon

[Gravy]

From the vid: "This is so obvious that a child could see it"

And I spent 15 minutes this afternoon watching my son try to fit a round block in a square hole because he'd just successfully got the square block to fit there...
DRBUZZO is your son? (http://forums.randi.org/showpost.php?p=3456541&postcount=111)

[MG1962]

hey NASA worked out how to get square pegs into round holes - saved a couple of guys on Apollo 13 :)

[arthwollipot]

The Big Puzzle (http://darwintalk.com/message-board-forum/about207.html) at Darwintalk.

Warning: long thread...

[Lynx2174]

Square pegs fit in round holes and vice versa if you use a sufficient amount of brute force.

There is the slight matter that either the peg or the hole won't be the same shape afterwards, but there's a price to pay for progress.


Also: this guy's a nutter. Not much else to say about that. Just watch the video in wonder and awe. Hard to believe that this fool is the same species as the people who invented the burrito and the computer.

[wilsontown]

given the mantle is a liquid

Nope! The mantle is solid, although one part of it (the asthenosphere) is reckoned to be partially melted, because it is a low velocity zone for seismic waves.

Generally, subduction has nothing to do with granite: it's oceanic crust that gets subducted, which is largely made up of ultramafic rocks and basalt. The point is that the subducted crust is relatively cold and dense compared to the mantle. If you want to say that subduction can't happen, you have to explain all the observations that suggest it does happen, for example the existence of seismic Benioff zones (http://en.wikipedia.org/wiki/Wadati-Benioff_zone) at subduction zones, and seismic tomography.

[Professor Yaffle]

We had Neal Adams (and yes he is also the comic book illustrator) turn up at Bad Science "discussing" his theory a while back. I will see if I can find the thread.

Edit: found it - unfortunately it is a TM/Bubblefish started thread, so you will have to wade througha lot of his crap if you want to read it.

http://badscience.net/forum/viewtopic.php?t=1238&highlight=expanding+earth

[CFLarsen]

Well, technically, he is right: Earth does grow bigger, due to the meteors and Earth sucking up space debris of various kinds.

As for the rest, e.g., the "conspiracy of science"....

This is a joke. Either way.

But, hey: Cool graphics.

[robinson]

It is an elaborate joke, right?

[Professor Yaffle]

It is an elaborate joke, right?

Nope, the guy really believes it. He also has a new theory of physics which can account for matter being created in the centre of the earth (hollow of course) which allows it to grow.

Edit: for more on the expanding earth

http://www.expanding-earth.org/

[madurobob]

I'm scared - is this big Earth balloon going to pop someday?

And how does he explain the Himalayas continuing to grow taller?

[Brown]

The Earth was once much smaller than it is today, apparently. How does this square with Al Gore's theory of global shrinking (http://forums.randi.org/showthread.php?t=78346)? This crisis was brought to the national attention early last April.

[Professor Yaffle]

I'm scared - is this big Earth balloon going to pop someday?

And how does he explain the Himalayas continuing to grow taller?

http://www.youtube.com/watch?v=nfgkm0eBGsc

[madurobob]

Wow - he actually claims that plate techtonics states India broke loose from the ocean floor and floated on the ocean to bump into Asia.

And "folding" and "recurving" created the Himalayas and India. Thats cute, but he never explains how this folding occurs when the Earth is expanding and the crust is being stretched (stretching makes folds?). And how come the distance from my house to Albequerqee hasn't changed in the past 100 years?

Dang - now I'm going to have to spend my day googling and watching youtube expanding earth videos. I must admit, his graphics are very cool.

[robinson]

How do you know it isn't a joke?

[Professor Yaffle]

How do we know anything "isn't a joke"?

Obviously I can't be 100% sure, but he certainly has invested a huge amount of time and effort on it over a long time which suggests to me that he really believes it.

[robinson]

How do we know anything "isn't a joke"?

Obviously I can't be 100% sure, but he certainly has invested a huge amount of time and effort on it over a long time which suggests to me that he really believes it.

Or he has a really good sense of humor. And I think he is making money as well. Too funny.

[Professor Yaffle]

All I wll say is that if he is joking/trolling, he is does a very convincing impression of a true believer. And really we can never say more than that can we?

[robinson]

He has always had a wicked sense of humor.

[CFLarsen]

Or he has a really good sense of humor. And I think he is making money as well. Too funny.

Is he making money from this?

[Agent : Orange]

He has always had a wicked sense of humor.

Neal Adams was on Coast to Coast a while ago, talking about the expanding Earth. I don't think he's joking from the way he presented the material and the amount of effort he's put into promoting his ideas.

But he can draw a kickass Green Lantern.

[robinson]

He is selling DVDs. Maybe he is so wealthy he doesn't need money. Maybe it is a hobby.

I'm still thinking huge practical joke. Due to one critical fact.

[CFLarsen]

He is selling DVDs. Maybe he is so wealthy he doesn't need money. Maybe it is a hobby.

I'm still thinking huge practical joke. Due to one critical fact.

Which is?

[Simplegreentinhouse]

The Earth, or the universe??????? The Earth at one time didn't exist and we are all made of "space dust". LOL.

[3bodyproblem]

It's not funny actually, future generations will have to deal with bumping their heads on the moon all the time.

[Simplegreentinhouse]

Don't talk ****** The Earth is more likely to collapse with the amount of oil being removed from under the earth ( Two different earths, the first being THE Earth and the second being the dirt/Earth's crust). Also think about gravity, no matter the size of the Earth the moon will still be a good distance away. Mass is alway conserved and only the mass of the earth or moon will have that much affect on the distance between the Earth and the moon. The mass of Earth is most likely decreasing because of the amount of payloads being sent into space. So by right, we ought to really be going away from the moon. Also the universe is expanding and thus the planets are moving away from each other, also if the Earth is truelly getting bigger, then it would be doing it at such a slow rate that future generations wouldn't bang their heads, they would be used to it, and if the moon were that close, I am sure people would either live on it or there would be huge signs telling people to "mind the step". Remember health and safety laws. The moon would be sued.

Also if the moon ever got that close, Earth would be gone. Gravity would be spluggered.

[Jimbo07]

Don't talk ****** The Earth is more likely to collapse with the amount of oil being removed from under the earth.

What an ironic pairing of phrases! ;)

[Simplegreentinhouse]

What an ironic pairing of phrases! ;)

What do you mean? :p

[blutoski]

How does this square with Al Gore's theory of global shrinking (http://forums.randi.org/showthread.php?t=78346)? This crisis was brought to the national attention early last April.

I'm reminded of an old Peanuts story arc where Lucy was on a crusade to get people to walk on the sidewalks. She'd heard somebody say 'the world is getting smaller' and figured it was from people walking on dirt and compressing it.

[dudalb]

Neal Adams should have stuck to drawing Batman,at which he is extremely good..in fact,IMHO,the best who ever drew The Dark Knight except for Bob Kane.
But he is making a complete and total fool of himself with his Expanding/Hollow Earth crap.

[dudalb]

Neal Adams was on Coast to Coast a while ago, talking about the expanding Earth. I don't think he's joking from the way he presented the material and the amount of effort he's put into promoting his ideas.

But he can draw a kickass Green Lantern.

I would really like to think this all a huge prank on the part of Adams,but based on several radio and television appreances, plus a few anectodtes told me by people who have met him at Comic Book Conventions, Adams really believes the crap he is pushing.
He is not doing it for money,since he has become wealthy from the Graphics Company he owns,which done the CGI for some very sucessful commericials.

[robinson]

One of my legs is getting longer than the other.

[robinson]

The answer might be found in Fantastic Four #263

http://www.beaucoupkevin.com/2007/01/science.html

[CFLarsen]

One of my legs is getting longer than the other.

What is the one critical fact?

[robinson]

Someone is pulling on one of my legs!

[athon]

Nope! The mantle is solid, although one part of it (the asthenosphere) is reckoned to be partially melted, because it is a low velocity zone for seismic waves.

I oversimplified, but it's also technically incorrect to call it a solid from what I understand. It has properties of both, in that there is a flow. You don't get convection currents in solids, after all.

Generally, subduction has nothing to do with granite: it's oceanic crust that gets subducted, which is largely made up of ultramafic rocks and basalt. The point is that the subducted crust is relatively cold and dense compared to the mantle. If you want to say that subduction can't happen, you have to explain all the observations that suggest it does happen, for example the existence of seismic Benioff zones (http://en.wikipedia.org/wiki/Wadati-Benioff_zone) at subduction zones, and seismic tomography.

I agree. However, to have any two solids mixing at all, you need what the mantle has. Heat, pressure and flow.

Athon

[BenBurch]

As pointed out above, it DOES get bigger over time. About 50 tons a day of in-falling meteoric material.

[robinson]

And around 500,000 tons of water each day as well.

[3bodyproblem]

Also think about gravity, no matter the size of the Earth the moon will still be a good distance away.

Hey, no re-writing of Newton's Universal Law of Gravitation.

[athon]

As pointed out above, it DOES get bigger over time. About 50 tons a day of in-falling meteoric material.

The 'Expanding Earth' theory isn't claiming that the Earth's mass is increasing by accruing extraterrestrial material, but rather it is 'puffing up', for want of a better term.

Athon

[Agent : Orange]

I would really like to think this all a huge prank on the part of Adams,but based on several radio and television appreances, plus a few anectodtes told me by people who have met him at Comic Book Conventions, Adams really believes the crap he is pushing.
He is not doing it for money,since he has become wealthy from the Graphics Company he owns,which done the CGI for some very sucessful commericials.

I've never met the guy, but he sure did take himself seriously on Coast to Coast AM (as much as anyone can on that show, anyway).

I agree with you about Batman, by the way. Adams' art is all round good.

[Agent : Orange]

The answer might be found in Fantastic Four #263

http://www.beaucoupkevin.com/2007/01/science.html

*lol*

Great find!

[ElMondoHummus]

I was first going to joke that there's some giant striding the earth trying to inflate it by blowing into old oil wells, with the hope that the absurdity of such a concept would provide a modicum of humor. Problem is, the original concept itself is so absurd that it's kind of hard to top. Expanding earth? What the heck?

Look, there's nothing wrong with trying to come up with alternate explanation for phenomena, but those explanations must be grounded in reality and be amenable to further support - or falsification - from observations. So, what obsrevations currently support the concept of an expanding earth? Are there any? The few arguments I saw on Neal Adams's site were simplistic to the extreme, and I don't see any of them being based in actual observations; rather, they all seem to argue conceptually.

Meh... that may be asking too much of the Expanding Earthists. Anyway, here are some questions about the hypothesis I'm coming up with:

Is the earth expanding and the density reducing (i.e. The "inflating" Earth effect)? If so, it's reasonable to assume that would be a measurable phenomenon. Is the density of material in the crust indeed going down (I single out the crust due to the fact that effects would be immediately and directly observable, whereas effects on the mantle and deeper segments are not)? Are there any observations that would support this?

Or,

Is the earth expanding and the density remaining constant (i.e. the "spontaneous generation of matter" effect)? If so, then mass is adding. That should be measurable in both rate of spin and gravity. Is either changing?

I'm actually asking those questions rhetorically. The point is that if the hypothesis posits an expanding earth, there should be measurable effects, and the proponents of the hypothesis should be able to produce such measurements. I'll go and dig into the info, but so far, I haven't seen any such evidence.

[robinson]

*lol*

Great find!

You realize that is from 1984, right?

A few more pages from that story can be found here
http://www.byrnerobotics.com/forum/forum_posts.asp?TID=17882&KW=JBF+Reading+Club%3A+Fantastic

[Mojo]

More here:

http://www.theness.com/neurologicablog/index.php?p=144
http://www.theness.com/neurologicablog/index.php?p=145
http://www.theness.com/neurologicablog/index.php?p=150
http://www.theness.com/neurologicablog/index.php?p=151

[Agent : Orange]

You realize that is from 1984, right?

I haven't seen it before, so it's new to me. I'm not much of an FF fan.

When did Adams start his expanding Earth nonsense?


A few more pages from that story can be found here
http://www.byrnerobotics.com/forum/forum_posts.asp?TID=17882&KW=JBF+Reading+Club%3A+Fantastic
Awesome, thanks!

[Professor Yaffle]

When did Adams start his expanding Earth nonsense?



According to him, he has been working on it for over 35 years:

http://badscience.net/forum/viewtopic.php?t=1238&postdays=0&postorder=asc&highlight=expanding+earth&start=135 (3rd post in thread).

[quarky]

Do nukes make the world lighter? Some loss of mass; energy radiating away from Earth?
What about helium? Doesn't it tend to leave the atmosphere over time?

Why am I getting heavier, yet less dense?

[Agent : Orange]

According to him, he has been working on it for over 35 years:

http://badscience.net/forum/viewtopic.php?t=1238&postdays=0&postorder=asc&highlight=expanding+earth&start=135 (3rd post in thread).

Wow.

That's a long time to come up with something so nonsensically craptacular.

[shadron]

And around 500,000 tons of water each day as well.

OK, Robinson, I'll bite - where did you get this figure?

I oversimplified, but it's also technically incorrect to call it a solid from what I understand. It has properties of both, in that there is a flow. You don't get convection currents in solids, after all.

The term usually used is that the mantle is "plastic", which gives it the possibility of slow flowing convection plumes over long periods of time. The subducted material (granitic ocean bed), as it descends, melts and rises as bubbles to the surface (plutons) because it is lighter and less viscous than the mantle material, due to water and other dissolved gasses.

[robinson]

OK, Robinson, I'll bite - where did you get this figure?

I actually had to calculate it out. That is the amount of water from small comets every day. Give or take 10 or 20 thousand tons, nobody really knows for sure.

[Dan O.]

If the earth were truly expanding we would have seen the effects. For instance, transoceanic cables would snap from the increased tension.

[The Bad Astronomer]

He says that continental drift is actually from the Earth expanding. That is simply wrong, fundamentally. if it were true, all continents would be moving away from each other as the Earth expands. However, we see some plates diverging and others converging. He would have to come up with some secondary mechanism to explain that.

I may research this more, as it's marginally astronomy and I get the occasional question about it.

Edited to add: I see he also states all planets expand. Bzzzt. Fault lines and scarps on Mercury show that the crust has actually shrunk as the planet cooled.

[CFLarsen]

I actually had to calculate it out. That is the amount of water from small comets every day. Give or take 10 or 20 thousand tons, nobody really knows for sure.

Where do you have your numbers from?

He says that continental drift is actually from the Earth expanding. That is simply wrong, fundamentally. if it were true, all continents would be moving away from each other as the Earth expands. However, we see some plates diverging and others converging. He would have to come up with some secondary mechanism to explain that.

I'll bet (were I a betting man) that he got that from The Expanding Balloon Analogy (http://www.phy.cuhk.edu.hk/phyworld/articles/univexpand/univexpand_e.html)

Cue to an excellent explanation:
"...theeeee universe itself keeps on expanding and expanding
In all of the directions it can whizz..." (http://www.bbc.co.uk/dna/h2g2/A2163133)

[robinson]

Where do you have your numbers from?

Ha! That is going to lead to an entire topic, which I have been avoiding for years. But rather than derail this one, I guess the time has come.

[CFLarsen]

Ha! That is going to lead to an entire topic, which I have been avoiding for years. But rather than derail this one, I guess the time has come.

No need for another thread. Just post your sources.

[robinson]

No way. And I checked, it is more like a million tons a day, but I did a low estimate just in case.

[CFLarsen]

No way. And I checked, it is more like a million tons a day, but I did a low estimate just in case.

Just post your sources.

[Rocko]

How do you know it isn't a joke?

Highly unlikely, I suspect. He was interviewed by the SGU team a while ago (a long interview, too - it took up the entire episiode), and there were no indications at all that he was anything other than serious.

http: //ww w.theskepticsguide.org/skepticsguide/podcastinfo.asp?pid=51

Sorry for the borked link; I'm still below 15 posts.

[robinson]

No way Larsen. It is worth an entire topic. Enjoy. Small comets from space!

http://forums.randi.org/showthread.php?postid=3466890#post3466890

[robinson]

Highly unlikely, I suspect. He was interviewed by the SGU team a while ago (a long interview, too - it took up the entire episiode), and there were no indications at all that he was anything other than serious.

I'm thinking Andy Kaufman style joke. One that you keep going for a lifetime.

[robinson]

As pointed out above, it DOES get bigger over time. About 50 tons a day of in-falling meteoric material.

I'm surprised nobody asked the obvious question. Where did you get that figure from?

[zeusbheld]

All I wll say is that if he is joking/trolling, he is does a very convincing impression of a true believer. And really we can never say more than that can we?
quite good either way... as comedy.

[wilsontown]

Nope! The mantle is solid, although one part of it (the asthenosphere) is reckoned to be partially melted, because it is a low velocity zone for seismic waves.

I oversimplified, but it's also technically incorrect to call it a solid from what I understand. It has properties of both, in that there is a flow. You don't get convection currents in solids, after all.

You can get convection currents in solids as long as temperature is high enough. Deformation of the mantle occurs through solid-state processes: largely dislocation creep and diffusion creep, with some grain boundary sliding.

[athon]

You can get convection currents in solids as long as temperature is high enough. Deformation of the mantle occurs through solid-state processes: largely dislocation creep and diffusion creep, with some grain boundary sliding.

I think we're arguing over semantics, then. Sure, sand is technically made of solid particles, yet flows too. The mantle has properties of both solids and liquids, in that overall it has convection currents and therefore as a mass, has flow.

Man, people can get so finicky over the silliest things. Shadron actually hit the nail on the head by describing the mantle as 'plastic'. Any way you cut it, the mantle flows; density has nothing to do with preventing plates from subsiding.

Athon

[wilsontown]

The term usually used is that the mantle is "plastic", which gives it the possibility of slow flowing convection plumes over long periods of time. The subducted material (granitic ocean bed), as it descends, melts and rises as bubbles to the surface (plutons) because it is lighter and less viscous than the mantle material, due to water and other dissolved gasses.

There's very little granite in the ocean floor. It's mostly ultramafic rocks (dunite etc), sheeted dolerite dykes, basaltic pillow lavas, and hemipelagic sediment. As far as we know, from seismic tomography and geochemical study, the downgoing slab of oceanic crust at a subduction zone doesn't itself melt. It gets recycled into the mantle. Meanwhile, the slab releases fluids into the overlying mantle, triggering partial melting and granite formation above the subducting slab.

[wilsontown]

No doubt I'm being a bit pedantic. But I'm still going to maintain that the mantle is solid. After all, it's made up of crystalline materials that possess long-range order. From a materials point of view, it's definitely a solid. Sure enough, it acts in a plastic manner, but that's not unexpected for solid materials.

Anyway, I think we can agree that there's plenty of evidence for subduction, and no reason for invoking density to say that it can't happen.

[Blue Mountain]

Highly unlikely, I suspect. He was interviewed by the SGU team a while ago (a long interview, too - it took up the entire episiode), and there were no indications at all that he was anything other than serious.

http://www.theskepticsguide.org/skepticsguide/podcastinfo.asp?pid=51

Sorry for the borked link; I'm still below 15 posts.

Here's a clickable link for those interested in a rather non-skeptical Skeptic's Guide to the Universe. The following week's episode has some interesting feedback. Download them both so when you get tired of Neal's theory, just skip forward to #52 and listen to that one instead.

[robinson]

As pointed out above, it DOES get bigger over time. About 50 tons a day of in-falling meteoric material.

Where does that figure come from? I don't believe that much material falls to Earth each day.

[athon]

Where does that figure come from? I don't believe that much material falls to Earth each day.

How do you have the right to ask others for their sources when you've flat out resisted providing your own? That's the problem with stating you don't have to show where you get information from - anybody can make any silly old claim and conversation isn't advanced one iota as it's all just one person's statement of understanding.

Athon

[robinson]

How do you have the right to ask others for their sources when you've flat out resisted providing your own?

Uh, dude, I started an entire topic about the sources, as well as questions and doubts about the entire issue. Did you miss that somehow?

[athon]

Uh, dude, I started an entire topic about the sources, as well as questions and doubts about the entire issue. Did you miss that somehow?

You did? I withdraw the statement with full apologies if that's the case.

Athon

[robinson]

You did miss it! Head on over, loads of fun.

No way Larsen. It is worth an entire topic. Enjoy. Small comets from space!

http://forums.randi.org/showthread.php?postid=3466890#post3466890

[3bodyproblem]

I know the Mississippi flushes some amount of silt out into the Gulf, as a result there is more mass nearer the equator. In effect the Earth is expanding about its waistline (and each day is just a tiny bit longer than the one before).

[quarky]

I know the Mississippi flushes some amount of silt out into the Gulf, as a result there is more mass nearer the equator. In effect the Earth is expanding about its waistline (and each day is just a tiny bit longer than the one before).

not sure about that.
Aren't most man-made lakes in the northern hemisphere?
Filling a valley with water probably rearranges mass more than the silting from big rivers.

[Rocko]

Here's a clickable link for those interested in a rather non-skeptical Skeptic's Guide to the Universe. The following week's episode has some interesting feedback. Download them both so when you get tired of Neal's theory, just skip forward to #52 and listen to that one instead.

Cheers for sorting that :)

[OMGturt1es]

No doubt I'm being a bit pedantic. But I'm still going to maintain that the mantle is solid. After all, it's made up of crystalline materials that possess long-range order. From a materials point of view, it's definitely a solid. Sure enough, it acts in a plastic manner, but that's not unexpected for solid materials.


you are corrent. it is a common misconception that the mantle is melted. it is solid. and it is "plastic".

[shadron]

There's very little granite in the ocean floor. It's mostly ultramafic rocks (dunite etc), sheeted dolerite dykes, basaltic pillow lavas, and hemipelagic sediment. As far as we know, from seismic tomography and geochemical study, the downgoing slab of oceanic crust at a subduction zone doesn't itself melt. It gets recycled into the mantle. Meanwhile, the slab releases fluids into the overlying mantle, triggering partial melting and granite formation above the subducting slab.

Yeah, you're right - I got my basalts switched with the lighter crust rocks.

I had heard that the crustal rocks melted when subducted due to higher amounts of fluids (mainly water) and gasses, and the the ascending dollops of those melts became the plutons exposed in the Yosemite Valley and the source of magma for the Cascades, for example. Ah, well, it was probably an over-simplistic explanation for non-geologists; glad to learn differently.

[arthwollipot]

I know the Mississippi flushes some amount of silt out into the Gulf, as a result there is more mass nearer the equator. In effect the Earth is expanding about its waistline (and each day is just a tiny bit longer than the one before).not sure about that.
Aren't most man-made lakes in the northern hemisphere?
Filling a valley with water probably rearranges mass more than the silting from big rivers.That is, as quarky pointed out, a mere rearrangement of matter. It's not actually changing anything. The expanding-earthists seem to believe that more matter is being created as the earth expands. Either that, or as has been pointed out, the existing mass is getting less dense. Neither of which has either theoretical or experimental support.

BTW, Novagaea, in the link I posted earlier (The Big Puzzle) felt that the earth was actually hollow, and it was just the "skin" getting thinner as the earth expanded. Furthermore, he believed that the earth expanded because the moon, hurled by jupiter, punched through the crust and bounced around the inside of the planet for a little while before punching out again and settling into its current orbit. Not only but also, he believed that this happened within historical times.

[OMGturt1es]

I had heard that the crustal rocks melted when subducted due to higher amounts of fluids (mainly water) and gasses, and the the ascending dollops of those melts became the plutons exposed in the Yosemite Valley and the source of magma for the Cascades, for example. Ah, well, it was probably an over-simplistic explanation for non-geologists; glad to learn differently.

actually, that's pretty close to what happens. the eutectic point (the pressure/temperature at which the first melting occurs within a system) changes with the addition of water. hence, hydrated material of a certain composition subjected to the same perssures begins to first melt at different temperatures than non hydrated material of the same composition. as unintuitive as it may seem, the addition of water tends to actually lower the required temperatures at cooresponding pressures at which the first melt begins. this is certainly true of oceanic basalt, which tends to be far more hydrated than the crustal continental rocks under which it is subducted.

this subducted material then becomes metamorphosed. generally, subducted, hydrated ultramafic rocks metamorphose into serpentinite, which is less dense than the surrounding peridotite. hence, boyancy tends to drive these large serpentinized rocks and any related partial melts upward.

this is generally where melting occurs. hot rocks are pushed upward into areas of lesser pressure, and decreasing pressure in a system tends to lower the eutectic point. as these hot rocks rise, they also heat up the continental rocks. as the pressures are far lower, melting of either can occur. heating and melting can lead to uplift and volcanism.

as volcanism kicks in, the least viscous melt is extruded first. the least viscous material is generally mafic. as the mafic protions of the melt are extruded, the melt becomes more felsic. hence, a melt with some mafic components (think oceanic basalt/peridodite) and some felsic componenets (think melted crustal continental rocks) will usually become more felsic overtime, as the least viscous material is more easily extruded. the leftover melt that is never erupted crystalizes, and is generally more silic (in this case, granitic) in composition. hence the large granitic plutons throughout the sierras.

so yes, in general, subduction leads to orogeny, and hydration and density are key components to this general rule.

...OR SO that is my understanding. i may have some details incorrect. i'm just a student. i'm guessing others here are more qualified than i, and may be able to correct any errors i've made.