Is the Earth growing?

[Gillianren]

How many of you are acedemics? Because you all sound like them.

Depends on what definition of the term you're using!

I have a Bachelor of Arts in English literature, which is why my posts tend to be perfectly spelled and precisely written (though I do tend to slip into a more casual style as well). I also took one quarter of geology, one quarter of paleontology, and one quarter of oceanography in college. Professionally speaking, I'm nothing; I'm on disability and don't work at all. However, if I were to get a job, it would probably be in academia.

[mutineer]

This is just plain wrong, I'm afraid.

Thank you for your response. I have been making my own inquiries, and Bristol University have also referred me to R. McNeill Alexander's book -- which I shall try to get hold of.

I endeavour to remain completely open-minded, but I note that the paper by Hokkanen for which you have provided a link is more than twenty years old. (And refers to work by Alexander published a decade or more earlier.) This does not change the math, of course, but it does change quite a lot else.

Hokkanen writes: " . . . land animals bigger than 100 000 kg should be in nature’s reach – yet the largest elephants are under 10 000 kg, and the largest mammal which ever walked on solid ground, Baluchitherium, weighed about 30 000 kg (Granger & Gregory, 1935). Even the most massive land animal, the dinosaur Brachiosaurus from the Jurassic period 140 million years ago, stayed at 80 000 kg (Colbert, 1962). It has been argued that the great dinosaurs were semiaquatic because of their mass, though this has recently been questioned."

Since the 1980s, larger beasts have been discovered. Estimates for Argentinosaurus do indeed reach up to that hundred ton (100 000 kg) mark. And as Hokkanen also writes: "The maximum load should contain a safety margin." "In the end a massive animal is unable to take a single step without the fear of a total collapse." I need to read the paper more carefully, but it seems to me that Hokkanen is expecting Nature to fall short of the standards of a reliable structural engineer in the matter of safety margins. If I am to conclude that African Elephants could get by with much spindlier legs than those they actually possess, I am not sure it is a conclusion I wish to reach.

Regarding the "semi-aquatic" claim, as I have previously indicated, it is now fairly well established that the great dinosaurs (with the exception of Sauroposeidon) were land dwellers.

There has also been a strong recent tendency among paleobiologists to regard the traditional picture of "slow and lumbering" dinosaurs as being in need of revision. Admittedly, I suppose we can retain the old stereotype for for the most massive of them.

Stephen Hurrell's book is the more recent and up-to-date! A lot has been learned about dinosaurs over the past quarter century.

Edit: Alexander's book NOW ON ORDER!

[grant hutchison]

I endeavour to remain completely open-minded, but I note that the paper by Hokkanen for which you have provided a link is more than twenty years old. (And refers to work by Alexander published a decade or more earlier.)

Well, you're the one who pointed out that:

This debate happened rather a long time before the Internet arrived ...

It's essentially been done and dusted for a few decades, with detailed mathematical support of the sort I linked to. The mainstream doesn't see a mystery to dinosaur weight-bearing.

Stephen Hurrell's book is the more recent and up-to-date!

It's certainly recent ...
But it's evident from his website that his purpose in driving against the mainstream maths is to support another ATM notion, the expanding earth, and that the scattered positive comments about his book come from EEers (though he neglects to point that out).

Hokkanen writes: " . . . land animals bigger than 100 000 kg should be in nature’s reach – yet the largest elephants are under 10 000 kg, and the largest mammal which ever walked on solid ground, Baluchitherium, weighed about 30 000 kg (Granger & Gregory, 1935). Even the most massive land animal, the dinosaur Brachiosaurus from the Jurassic period 140 million years ago, stayed at 80 000 kg (Colbert, 1962). It has been argued that the great dinosaurs were semiaquatic because of their mass, though this has recently been questioned."
...
Regarding the "semi-aquatic" claim, as I have previously indicated, it is now fairly well established that the great dinosaurs (with the exception of Sauroposeidon) were land dwellers.

I don't think anyone questions that: certainly Hokkanen's paper makes it clear that even very large (>100-tonne) creatures wouldn't need to be semi-aquatic. His very next sentence after the text you quote is "From the point of view in this study Brachiosaurus could have been at least a couple of times bigger and still have walked on land."

Anyway. With my link, Alexander's work and Hurrell's book, you'll now be able to compare the mathematical treatments in detail and come to your own conclusions.

Grant Hutchison

[ToSeek]

There are two separate discussions going on here. We're going to close the thread until one of them can be split off into its own thread (should be done within the next 12 hours).

[Nereid]

[Moderator Note]

At the request of ExpErdMann (and others), posts relating to the specific ATM idea ("slow EE" - expanding Earth), which ExpErdMann is a proponent of (or at least working on a paper on) have been split from this thread, into a new thread: "Slow EE" ATM idea

As the original thread had a complicated history*, and as there are several posts which are relevant to both threads, the split is not entirely clean; my apologies. You may need to refer to the other thread to get the full context of some of the posts here.

If there are posts which are obviously now in the wrong thread, please PM me (or another mod) with detailed info about them, and corrections will be made.

As ExpErdMann said that he (she?) had not intended to present, and defend, an ATM idea; the new thread is now closed. Please continue to question, challenge, defend, etc the ATM idea(s) presented by EvilEye (and others) in this thread, which will reach its 30-day limit on 21 April (I added an extra day, to cover the time spent offline while the split was being made).

*It began in the Q&A section before the new ATM policy was announced, was moved to the ATM section (after the policy change), and involves at least two, largely separate, discussions.

[/Moderator Note]

[mutineer]

It's essentially been done and dusted for a few decades, with detailed mathematical support of the sort I linked to.

I guess I should now read and read and read before responding, but let me take up one thing with you.

My understanding of the work that was done back in Victorian times to establish that there was a weight problem was that it was of this nature:
The diameters of the femurs of a range of animal species (mice thru cats thru pigs thru horses thru elephants, etc) were plotted against their weights, and a "best fit" equation was obtained and thence a standard deviation. When the data for the brontosaurus was added to the picture, it was readily seen that it deviated so far from the best fit as to yield a tiny "p" (probability) value.

Now this approach was engaging the matter from a "this is what nature shows us" perspective. Also, with a modest degree of qualification, it involved data that would not become outdated as a result of new discoveries.

Is it my understanding that if I were able to turn up an old paper that covered this territory, or even if I were able to assemble similar data with a similar result, you would be unimpressed by this methodology?

(I am pretty sure the Victorians looked at the mechanics too, but let's leave that aside.)

[grant hutchison]

My understanding of the work that was done back in Victorian times to establish that there was a weight problem was that it was of this nature:
The diameters of the femurs of a range of animal species (mice thru cats thru pigs thru horses thru elephants, etc) were plotted against their weights, and a "best fit" equation was obtained and thence a standard deviation. When the data for the brontosaurus was added to the picture, it was readily seen that it deviated so far from the best fit as to yield a tiny "p" (probability) value.

I'd be surprised if the Victorians did anything as involved as this: hypothesis testing using the standard deviation to derive p values wasn't introduced until a few years after Queen Victoria died. But I can certainly imagine that they might plot a graph and draw a line through the points.

Is it my understanding that if I were able to turn up an old paper that covered this territory, or even if I were able to assemble similar data with a similar result, you would be unimpressed by this methodology?

I'd suggest it's a little naive.
Bones don't generally break in pure compression (unless subjected to a massive overload); they break under bending or twisting forces. An elephant could get by with very spindly legs indeed if it simply stood in one place with its legs vertical; but it would be unable to walk without generating critical bending forces.
So the length of a bone is also of importance, as well as its curvature and the size and location of muscle attachments (which determine where bending forces are applied during locomotion). Alexander uses a quantity combining bone cross section, bone length and estimated bone loading as a measure of a bone's ability to withstand bending forces generated by locomotion: Apatosaurus scores rather better than an elephant in this regard because of the relative shortness of its limb bones.

So I'd urge you to do the background reading.

Grant Hutchison

[mutineer]

So I'd urge you to do the background reading.

Even though I have learned new things in the past 24 hours, I shall now contain myself and shut up until I have read McNeil Alexander . . . now in the mail from the USA! (How can a man with the benefit of a Scottish education not be beguiled by such a name? Or indeed by your own!)

[truedreamm]

This has bothered me for some time.

Dinosaurs were HUGE, but the largest land animals now are much smaller.
I wonder if this is because there was less gravity millions of years ago.

hello evileye, some of your idea is true.

Dinosaurs were HUGE, but the largest land animals now are much smaller.
I wonder if this is because there was less gravity millions of years ago.
this have some truth !!!
it is better way to see in true science view, millions of years ago in earth there was equal gravity and anti gravity force. The soruce of anti gravity feild is liquid core of earth, and millions of years ago liquid core of earth was very young so it produced more anti gravity force in our planet. as time passes its ageing.

then the Earth would have had to have had less mass (been smaller).Is the Earth growing? this is a wrong idea.so earth is not growing but earth is ageing (liquid core) was the source in changes in gravity feild.

I think its time now to see some more deep about gravity and atmosphere

Present gravity of earth was the result of mainly four source of gravity field.
Flux of sun (gravity of sun), gravity of solid core, gravity of liquid core and gravity of atmosphere.Points to remember don’t only see the mass its useless, see only the force of it.

Let us separate Earth into tree main parts, solid core, liquid core and atmosphere. With respect earth: solid core is made up of high gravity atom, liquid core is made up of semi gravity atom and atmosphere is made up of anti gravity atoms.
This liquid core plays important role in planet, from the beginning of planet formation they work as semi gravity and semi anti gravity.
This semi gravity of liquid core was controls or capture by solid core.
This semi anti gravity of liquid core controls or capture the anti gravity atmosphere.

if you like know more about true science see this thread http://www.bautforum.com/showthread....595#post939595

Regards muthu