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Original posting from Reddit
I am posting this here in the hopes that an ornithologist might be able to shed some light on this unusual finding. Locality is Boise, Idaho.
This appears to be a roughly spherical mass approximately 6 cm diameter, most of which comprises tightly packed feathers with a central core of dermal tissue. The mass has been parasitized by maggots.
I speculate that this is some kind of tumor, which detached from the afflicted organism, and the decaying tissue attracted flies after detachment. But that's just a guess. If anyone has seen such a phenomenon before, please feel free to enlighten me!
Note, I am not the individual who found this object. I am merely relaying the question to this forum.
This is a flap of feathered skin from a Mallard, birds do not shed their skin. The bird in question is likely dead or at the very least, severely injured.
The skin and curved feathers has curled up around itself into a "ball". As it's flattened/separated you can see there is reddish skin with some tissue on it the maggots have gathered on. The feathers here are relatively small and curved and the pattern is SPOT ON for the breast/belly feathers of a Mallard.
While it's not really obvious in the photo of the Mallard below, it is very common for them to have that little bit of pale edging on the dark reddish-brown feathers, as seen in the first photo.
Photo by Jo Garbutt (Flickr: https://flic.kr/p/jVbHwP )
Most of a Supersaurus vertebra, with paleontologist glamor shot for reference. The shape of the bone identifies it as a sauropod, and its size of the fragment marks it as one of the largest land animals that ever lived. [Credit: Sauropod Vertebra Picture of the Week/Mike Taylor caption corrected from previous version]
I first read about that hypothesis in Brian’s book, My Beloved Brontosaurus, but despite my intentions, I didn’t follow up until a series of tweets from baseball player Jose Canseco received widespread mockery last week. Here’s a sample of what Canseco posted to Twitter:
Gravity had to be weaker to make dinosaurs nimble
— Jose Canseco (@JoseCanseco) February 19, 2013
My theory is the core of the planet shifted when single continent formed to keep us in a balanced spin
— Jose Canseco (@JoseCanseco) February 19, 2013
The land was farther away from the core and had much less gravity so bigness could develop and dominate
— Jose Canseco (@JoseCanseco) February 19, 2013
It’s easy to mock Canseco for saying things like that, but let’s face it: every report, every column, every mockery only made fun of him without explainin g what’s wrong with what he wrote. (Think of this post as my personal atonement for having done that.) While Canseco, based on his hostile response to Bill Nye, doesn’t seem to understand that scientific theories require evidence to back them up, some scientists had proposed weaker gravity as an explanation for big dinosaurs. Knowing why those scientists—and Canseco—are wrong is important. The question “how do we know Earth’s gravity didn’t change radically over 100 million years?” is a variation on the most important question we can ask about science: how do we know what we know?
I’m not sure exactly how much weaker gravity must be in either Canseco’s or the other hypotheses. We don’t need to be as extreme as Canseco thinks, though: he states the weight of Supersaurus to be about 200 tons. Current estimates place it closer to 40 tons: it was a pretty slender beast compared to its length! (In fairness, 40 tons is hardly skinny: the record-setting male African elephant was about 11 tons. Sauropods were still big animals.) To quote Brian, “Sauropods were weird from snout to tail.”
For the sake of argument, however, let’s assume the largest land mammal was as big as any animal can get: the 20-ton Paraceratherium, which lived in the Oligocene (about 23-34 million years ago). This is consistent with some earlier estimates, which means that gravity in the Jurassic Period (when Supersaurus lived) must have been about half what it is today, or something else must have been going on.
The weight of evidence (ha!) is that sauropods could and did get that big, not because of lower gravity or higher oxygen content, but because of their reproductive strategy. They were lighter than earlier scientists thought because they were very bird-like in bone structure and respiratory system, allowing them to survive under normal gravity and oxygen levels. Having started the discussion of weaker gravity, though, let’s carry it through to the end.
(Note: I still haven’t determined the source where weaker gravity is proposed, so I’m inferring its arguments from later papers. It’s evidently discussed in a later paper on the theoretical maximum size any mammal could be, but this one is unavailable to me without the appropriate academic credentials. However, here’s the citation: Economos, AC. The largest land mammal. Journal of Theoretical Biology. 1981 89:211–215 .)
The gravity of the situation
Earth’s gravity—as with any planet, star, moon, asteroid, etc.—is determined primary by its mass and size. Mass is (roughly speaking) the amount of matter in the planet, and that’s something hard to change drastically: if you wanted to make gravity noticeably stronger, you’d have to add the equivalent mass of another planet or moon, something that can’t just happen spontaneously. While Earth is constantly being bombarded by tiny asteroid fragments and dust grains, and is also losing small amounts of its atmosphere to space, neither of those effects is very big. To my knowledge, nobody has proposed the idea that Earth was lighter in the past as a solution to dinosaur size anyway, so let’s leave it alone.
The relationship of gravity to size: if two objects have the same mass, but one is smaller than the other, the smaller object will have correspondingly higher surface gravity.
A somewhat more reasonable idea is that Earth shrank. (Again, Canseco didn’t propose this idea, so please don’t take this as a strawman argument. I’m covering many possibilities to be thorough!) When Earth formed, its was molten rock, a completely different planet than it became subsequently. As it cooled and solidified, it would have contracted, shrinking by a noticeable degree. We see effects like that on the Moon and Mars, where the dramatic canyon Valles Marineris may have formed when the crust fractured, then grew bigger via erosion.
However, there are two strikes against that as an explanation. First, while the 65 million years since the last dinosaur is a long time by human standards, Earth has been around 4.5 billion years. The cooling-down period ended long before the colonization of land by animals, which itself happened long before the first dinosaur. The second problem is that, to double Earth’s gravity between Supersaurus and today, Earth would have had 1.4 times the diameter in the Jurassic. While that doesn’t sound like much, it translates to twice the surface area and nearly three times the volume of modern Earth. That’s a much bigger planet! (For the details of this calculation, see the note at the end of the blog post. For more about gravity, see my post on Le Petit Prince and the inverse square law.)
Blue plate tectonic special
Earth isn’t a perfectly smooth sphere, and its composition varies somewhat from place to place. That means both the density of rock and the gravitational force vary slightly around the planet. It’s not a huge variation, but it’s measurable and important if you work in a field where knowing precisely what direction is “down” is important. (To wit: if you’re trying to design a water system for a city, you’d better know how gravity will affect the flow of water, or else you might end up with stagnation or low pressure.)
Eastern and western hemisphere geoids: variations of the Earth’s gravitational influence, as measured by the GRACE satellites. The lumps and colors both indicate deviations from the average, with red indicating slightly stronger gravity, and blue indicating slightly weaker. [Credit: NASA/EOS]
The continents during the Jurassic Period, the age when the biggest sauropods lived. The supercontinent of Pangaea had broken up into two smaller pieces, but most of Earth’s landmass was still concentrated on one side of the globe.
During the Jurassic period, the continents had just broken apart from Pangaea, the supercontinent encompassing most of the land in the entire world. That meant that most of the landmass on Earth was still concentrated in one hemisphere. In his tweets, Canseco conjectured that this land concentration actually shifted the position of Earth’s core in compensation. A moment’s thought lets us dismiss the “compensation” argument: if the location of the continents made such a difference, wouldn’t it result in increased gravity rather than reduced? However, let’s take the hypothetical results at face value.
Earth’s interior is strongly differentiated, meaning that below the surface (the crust) there are distinct layers. The mantle is a region of rock heated until it behaves like plastic: mostly solid, but capable of flowing like a liquid under high pressure. The core consists of two regions: the molten outer core (made largely of iron and nickel) and the solid inner core. The temperatures are highest at Earth’s center, but because the pressures are also highest, the inner core stays solid, much like you can heat water far beyond its boiling point in a pressure cooker. To move that core around would require rearranging Earth’s interior pretty drastically. The crust is no more than 50 kilometers (30 miles) thick at most, which sounds like a lot until you realize that Earth’s average radius is 6371 kilometers. (I say “average” because Earth isn’t a perfect sphere.) Even with a relatively high concentration of crust on one side of the globe, you couldn’t shift the core very much: the forces aren’t strong enough.
The truth is that Earth’s tectonic plates, on which the continents rest, are always in motion, rearranging themselves very slowly over tens of millions of years. Yet the Moon reliably orbits, which wouldn’t be true if plate tectonics made a huge difference to Earth’s gravity. In fact, there’s another sign Earth’s gravity hasn’t changed much in the last 100 million years: the Moon is actually moving away from Earth, albeit very slowly. If Earth’s gravity had doubled since the time of the sauropods, we would expect the opposite effect.
Admittedly, this may seem like using a sledgehammer to crush a gnat. I’ve expended a lot of words and diagrams to combat a few short tweets from a baseball player, which he may or may not have thought very carefully about. However, as with many far-out “what if?” ideas, the real answers are known by science, and can be tested. Canseco, to his credit, did hypothesize something that’s testable that his ideas are wrong doesn’t make him any worse than many others who have postulated such things over the centuries. While it’s doubtful he’ll read either my post or Brian’s companion post on sauropod anatomy, the answers are out there, if he wants to know. Inquisitiveness is part of science being open to new knowledge (and I certainly learned a lot writing this post!) allows us to move from naive speculation to a deeper understanding of our world.
Notes on the physics
The strength of gravity at the surface of Earth, which tells how much a falling object accelerates, is determined by Newton’s law of gravity:where g is the acceleration, G is Newton’s constant (just a number that tells us the strength of gravity), and R is Earth’s radius. If we assume Earth’s mass stays the same, for the reasons I mentioned earlier, then changing gravity is a matter of changing Earth’s size and/or its shape.
Let’s consider a change just in size first, so Earth maintains its spherical shape. What we care about is the ratio of gravity now to gravity then, and what that means for the change in size:If gravity now is twice what gravity was then, the ratio is 2, and the radius then would have to be √2 = 1.41 times larger than Earth’s radius today. Earth’s surface area goes like the square of the radius, soIn words: double the gravity now implies double the surface area of the planet then.
If Earth’s mass isn’t distributed evenly, as in the Canseco conjecture, we can still use Newton’s law of gravity, adding up the effect of all the bits of mass to get the net effect at a position on the surface. (That’s a large part of the construction of the geoid I mentioned earlier.)
56 Responses to “Was weaker gravity responsible for large dinosaur size?”
Hi, Matthew, good to see this discussion. Just wanted to point up a potentially misleading statement in the caption to the Supersaurus-vert illustration.
You say “The shape of the bone identifies it as a sauropod, and the size of the fragment (that’s not the whole vertebra!) marks it as one of the largest land animals that ever lived.”
You’re right that the vertebra is not quite complete but it very nearly is. The only significant part that’s missing is the prezygapohyses — bony protrusions that overhang the front of the vertebra. You can see several nice examples in the second illustration at http://svpow.com/2009/09/06/bifid-brachiosaurs-batman/ The missing part would have been pretty small.
Thanks – I was under the impression the fragment was missing more than it really is. I’ve corrected the caption.
I think I read about 20 of the posts at SVPOW to prep for my post (so many sauropods!), but I decided against talking about Amphicoelias. I’m a mere physicist, unqualified to talk about what little evidence we have about it!
Apparently the expanding earth theory is quite popular in some circles. http://www.youtube.com/watch?v=_f6hcGJbjL0
I don’t think a YouTube video series counts as something being “popular”. Not only is there zero evidence for it, there’s a lot of strong evidence against it.
Given the number of views and similar videos I would say its popular enough. Certainly not in scientific circles, but then again nor are conspiracy theories. The fact that this video even exists and has been watched more than the odd numberphile video is a sad commentary on our society.
Reduced gravity on an Expanding Earth is discussed here:
[YouTube link removed by blog owner]
Sorry, I will not allow YouTube links to dubious hypotheses on my blog. As both my post and Brian’s state, there is no need for different gravity in ancient times, and no physical mechanism by which it could be reduced.
No discussion allowed then?
Posting a 15-minute YouTube video is not “discussion”.
How about a link to a technical paper on reduced gravity. Is that allowed?
An interesting paper, I liked the discussion of the scale of life under various strengths of gravity. (It makes me wonder about the scale of life in water, where gravity is offset by buoyancy, and especially in very saline environments.) but I am not sure that I can follow that line of logic to ancient life. (I would consider it possible that weaker gravity could be responsible, but it does not by far exclude other possibilities.) I have never been a fan of the expanding earth hypothesis.
That is hardly a technical paper, and would not pass peer review in any reputable journal because it has no scientific merit. There is no reason to believe Earth’s gravity was weaker in previous times. Dinosaurs could stand up under their own weight and the large flying reptiles had no trouble getting airborne. Additionally, there’s no evidence Earth changed size for reasons I wrote extensively about in the original blog post, and there’s certainly no way it could change mass.
I am terminating this discussion now. You can write about your ideas in your own space, but this blog is devoted to science.
Have you considered the effect on the weight (i.e., not mass) of dinos that would accompany a radical change in the rotational frequency of the earth (e.g., a change caused by the earth “toppling” its axis and loosing a lot of spin while its axis was aligned with its orbital plane)?
The mass of all life put together is tiny compared to the mass of nonliving matter on Earth – the rocks in the interior, the core, the mantle, etc. Weight in this case is proportional to mass, so it’s not a separate consideration.
(This reminds me that I should blog at some point about what “weight” actually means. Memo to myself!)
As you suggested I’ve written up my comments about your blog and put them here:
Let me know your comments on your blog, my website or email, twitter etc.
Also Brian Switek was telling me last night on twitter that his new book has a small bit about gravity in it. Do you discuss it anywhere else?
I hadn’t realized that Canseco’s idea was linked to an expanding Earth. I went through a lot of the problems with that concept here:
But was only scratching the surface of the problems.
I think Stephen is misrepresenting Canseco if he thinks he’s an ally to the “expanding Earth” hypothesis. I had a long Twitter conversation with Canseco on Friday night (blog post to come), and he’s genuinely interested in the science.
I wasn’t trying to imply that. Apologies I if gave that impression. The EE link is interesting though – always interested in augments against it as for it.
Just tried to reply on your article but it didn’t seem to want to play, so perhaps I’ll just reply here…
[remainder of comment excised for being a response to another post]
Kindly do not leave comments intended for another post on this one.
Allow me to reiterate a point I’ve made before: this blog is not a forum for advertising your own personal theories on ancient gravity, dark matter (or lack thereof), why quantum mechanics is wrong, aquatic apes, or similar. I will automatically delete comments that consist only of advertisements for such work, just as I would for commercial products.
My comment is not an advertisement. It supports the subject of this thread, i.e., Mr. Canseco’s assertion that surface gravity was lower during the dinosaur era.
Your steadfast opposition to posters who have different views, than yours, about the possibility of lower surface gravity in the distant past gives one the opinion that you have an agenda which you are not revealing. Are you threatened, economically or otherwise, if it turns out that it is scientifically established that surface gravity was, in fact, lower in the past?
Or maybe he just doesn’t have an obligation to give equal space to pseudoscience on his blog?
Well….one day his comments on the reason for dinosaur gigantism will, in retrospect, be considered pseudoscience.
That’s Dr. Francis to you, sir.
Read the blog which addresses Jose Canseco’s comments and an explanation for dinosaur gigantism:
[link removed – this blog is not a place to expound your personal theories]
The expanding earth theory (and even the hollow earth theory) is just as idiotic as the theory that the Sun was the center of the solar system 500 years ago.
I will remind all commenters that I do have a commenting policy: https://galileospendulum.org/commenting-policy/
Please abide by these rules, or run the risk of having your comment deleted. Crying “censorship” is foolish in any case: I’m not shutting you up in your own space, just in mine. This goes double if you insult my intelligence and that of my readers. Thank you.
No, I don’t see any sort of ‘dashboard’ all I can see the the ability to cancel a reply. It may be my script blocker, I have to use a rather severe one to keep my somewhat outdated PC safe. Feel free to remove the comment.
Yet another comment deleted for expounding a theory of changing gravity. Please read my commenting policy (https://galileospendulum.org/commenting-policy/) , especially item 3:
“On a similar note, the comments are not a space for you to expound on your own theories, promote your own ideas, or tout conspiracy theories. I reserve the right to edit or delete comments of that sort summarily. You can start your own blog and write whatever you want there (within limits, of course), but you don’t have the right to expect me to provide free advertising space for you. If you feel the need to compare yourself to Copernicus, Einstein, or Galileo, then you’re probably going to find yourself edited or deleted.”
It’s particularly ironic that people think they’ll find a sympathetic forum for a theory of changing Earth gravity in a post where I argue *in detail* that such theories aren’t viable or even necessary.
The size of the Earth is an equilibrium between internal pressure due to compression and weight due to gravity. It can’t easily be smaller because then it wouldn’t be in equilibrium.
The only way I can see for Earth’s gravity to change is if the Earth’s mass changed because the mass of the proton changed. That’s new physics to put it mildly but it’s more possible than any of the other ideas I’ve seen on this page. (I’m discounting the gravitational constant changing because that’s basically meaningless – it’s 1 in fundamental units, which the proton mass isn’t.) A smaller proton mass would mean a lower gravity, which would mean a larger Earth, which also means lower gravity.
The smaller Earth surface area today would have required recycling of ocean floors but if it happened over tens of millions of years then maybe the continents could survive. I’d guess we have the evidence to rule out that much recent shrinkage but I don’t know for sure. (My background is physics, paleontology is a hobby.)
One downside of lower gravity, from a pterosaur’s point of view, is that the atmosphere thins out. That would take away some of the benefit of the lower gravity. Probably no big deal for a sauropod, though – thanks to those handy air sacs.
In fact those air sacs are such an advantage it’s a wonder birds didn’t take over the world (even more than they have). My guess is that it’s because mammal blood balances avian lungs – denucleated erythrocytes means small capillaries which is also a huge metabolic advantage. Has much work been done on this?
Excellent demonstration! Could you do the same to show that higher air pressure could not have sufficiently reduced the weight by means of buoyancy?
If not a change in the fairly secure physics of gravity, what are your views on what else could have been responsible for the large size of dinosaurs. In particular, how could pterosaurs ‘fly’ when it has been proved impossible in a modern atmosphere. A fifty-ton whale can ‘fly’ in water. Any views on an atmosphere which might support the mass of a dinosaur/pterosaur?
Kindly reread both my post and Brian Switek’s post(s). There’s nothing impossible either about large dinosaur size (as I emphasized in my post, and as Brian has noted many times) or about pterosaur flight. There’s no evidence that Earth’s atmosphere was markedly thicker 65 million years ago, either, based on analysis of the sediments and plants of the era.
Earth’s atmosphere did have a much higher oxygen content in the Carboniferous period (the era of the huge flying insects), but that was long before the dinosaurs.
In our posts, Brian and I took pains to point out that, while dinosaurs are phenomenal in many ways, the mystery of their large size has been solved without the need to hypothesize crazy physics or geological phenomena. Yet you commenters still demand that I/we address theories that aren’t necessary.
I am struck by your extremely strong statements that are in complete disagreement with the evidence. Let’s just look at just two of your most misleading statements. “There’s nothing impossible either about large dinosaur size (as I emphasized in my post, and as Brian has noted many times) or about pterosaur flight.” and “… the mystery of their large size has been solved ” It is common knowledge that when the paleontology had an RC model of a pterosaur built that despite all of their cheating it still could not fly. When you say that the problem is solved who believes you beside yourself and the handful of people that submitted this nonsense hypothesis?
Remote-controlled models are neither here nor there. (Has anyone made a realistic mechanical model of a bird or bat that flies exactly the same way, from take-off to landing? Yet we know how birds fly very well, even the weird ones like albatrosses.)
“There’s nothing impossible either about large dinosaur size (as I emphasized in my post, and as Brian has noted many times) or about pterosaur flight.”
Your post from which I have quoted above is, if I may say so, very un-scientific. Your sweeping statements that ‘pterosaur size and flight’ is all known about is plainly ridiculous. This is supposed to be a scientific forum, not the bar in the local pub!
I have no ideas about what made dinosaurs grow large – that is well outside my knowledge or interest. However, as an aerodynamicist pterosaur flight most certainly is.
Whenever I read items about flight from palaeontologists, they invariably give away their degree of innocence concerning both the theory an practice of aerodynamics. Let me give you some examples:
First: ‘There are three types of flight – gliding, soaring and flapping’ Wrong. There are only two. Soaring IS gliding – it is merely done in a block of air which is rising (either dynamically or thermally) faster than the ‘glider’ is descending.
Second The idea that Quetzelcoatas n. could launch itself in single bound is so ridiculous it brings to mind Batman and Spiderman with their improbable feats. How can a creature the size of a giraffe, with a wing loading greater needing a speed of over 30mph to generate lift, get to that speed in a single bound (with its wings still folded by the way).
Then we have Chatterjee and his ‘biplane’ theory!
I came into the field of bird flight 40 years ago as a Cadet at the RAF College and the topic comprised my graduation thesis. Since then I have been flying model aircraft (including model birds) and I have also had access to RAF Wind Tunnels, to run tests on recently killed bird wings.
I have tried all the various hypotheses including flight in ground-effect Chatterjee’s sailboat (which, since it isn’t flight, doesn’t count) the idea that Q.n could only take off from a high slope and a stiff breeze and several more that challenge the flat-earth theory for stupidity.
Since you are so confident that Q.n could fly in an atmosphere like the present, let’s see something more scientific please. A few numbers and demonstrations might help.
Yes, those articles I linked are non-technical pieces aimed at non-specialists, but they point to decades of published research by experts. If you follow that trail, you’ll see figures and numbers whether you’re satisfied with that research or not isn’t my call. I am happy to defer to experts when I’m out of my field, just as I hope they would defer to my expertise when appropriate (e.g., gravitation and cosmology). My point is merely that the research exists, and that paleontologists are not stupid people: they aren’t working on models of pterosaur flight by guessing.
Dear Dr Francis,
Thanks for your reply, but I’m afraid it was a real cop-out. Your paleontologist colleagues indeed ARE working on models of pterosaur flight by guessing! Do they really know what a snap-stall is? Or the function of the alula feather?
Your point that the “research exists” is lost on me I’m afraid. I haven’t been able to find a single article or paper that remotely convinces me that a beast the size of Q.n could fly.
For example, which paleontologist would put his/her reputation on the line over the real weight of Q.n? 200Kg? 2000Kg?
Pennycuick? Rayner? Habib? Chatterjee? Witton? Hone? Conway? Elgin? Wellnhofer?
For Q.n I use 700 Kg / 12m span / 1.7m mean chord / 35Kg/m2 wing loading in my calculations. The result is a creature with the flying ability of a house-brick! Either some of these have got to be reconsidered radically, or the formulae for modern aerodynamic theory needs to change instead. Air density is about the only one we can alter. Thick Atmosphere?
Give us the numbers (weights, lengths, masses etc) and we can pin down the physics. That is all we aerodynamicists need to work on.
But with the physical characteristics given to us by the paleontologists, I would put my reputation (such as it is) on Q.n being unable to fly. (Lets stick to simple gliding for the moment, we can look at takeoff and flapping flight later).
I put it to you, Dr Francis, that Q.n could not glide, even if it took off from a huge cliff. By glide I mean that it could not sustain controlled descending flight below about 70mph. That is not to say that it couldn’t crash-land at the bottom (rather like my own hang glider landings) with a snap stall flare. But then what does it do? How does it get airborne again, having assumed it has landed like a vulture to eat. With a stall speed of 70mph, it would need Dr Habib himself to give it a powerful push to get it up to the 70mph launch speed in the single bound he has allowed it!
People think that the Wandering Albatross has difficulty taking off. It does, but only from land. With webbed feet, constant high winds and waves that can push it up into the airstream, Diomeda Exulans gets airborne much more easily from the sea than from the land. I know because I have watched them from the Falkland Islands. Incidentally did you know that D.E and it’s cousin the Giant Petrel fly more than twice as fast as the largest northern hemisphere gulls. These birds fly really fast – a function which cannot be appreciated on film or TV. I have stood on the harbour wall at Port Stanley. As an RC Glider enthusiast, I can tell you that these birds were whistling past me at twice the speed of my models. This means that their stalling speed would be nearer to 50mph than a gull’s 30mph. Wing loading again.
So give me your vital statistics for Quetzalcoatlas and we can work on the aerodynamics between us. You give me what you think they are, and I will tell you they don’t work!
Quetzalcoatlus northropi is the smoking gun for reduced surface gravity during the Mesozoic. Reasonable people realize that a flying animal, whether a reptile or not, that is frequently illustrated as being as tall as a giraffe, could not possibly fly if it existed today.
Robert T. Bakker, in his book ‘The Dinosaur Heresies’, observed the following:
The experts divide all pterodactyls into two groups: short-tailed and long-tailed. He notes that most of the long-tailed pterodactyls were wiped out at the Jurassic-Cretaceous extinctions, leaving the short-tailed pterodactyls to prosper but doesn’t venture an explanation for this. He does offer a characteristic of the short-tailed pterodactyls that, I believe, helps to explain this. He notes that the short-tailed pterodactyls had longer forearms.
If surface gravity increased during the late Mesozoic, pterodactyls that were able to evolve an increase in their wing area to mass ratio would be better suited to survive. And, as surface gravity continued to increase, pterodactyls with larger and larger wings should evolve. This is exactly what we see. The longer forearms of the short-tail pterodactyls may have given them the advantage in increasing the wing area/mass ratio. A rapid increase in surface gravity at the end of the Cretaceous along with a limit to the wing area to mass ratio would doom all pterodactyls.
I wrote a fairly comprehensive reply to your blog.
It clearly doesn’t accord with Dr Francis opinions. Sorry. If you want to continue the discussion, we’ll have to find another blog.
Incidentally, a propos the gravity theory just assuming we could prove that there was increased gravity in the Mesozoic. How did it disappear again?
At least with the ‘thick atmosphere’ hypothesis, it is feasible to imagine the atmosphere being ‘sucked’ away by a passing event (one of the newly discovered rogue planets perhaps?)
Most people who think about how the Earth’s surface gravity could change believe there are only two possible causes:
1. An expanding Earth.
2. A contracting Earth.
There is a third explanation. What would happen if the Earth’s cores and densest part of the lower mantle moved off-center (remaining in the equatorial plane)? Surface gravity would lower on one part of the surface and commensurately lower antipodally, i.e., a gravitational gradient around the globe. And, if the 3 parts periodically moved back toward Earth-centricity and away again, there would be corresponding rises and falls of surface gravity.
There is a logical explanation for how the above described movement could happen.
The fourth option is actually the correct one: there’s no plausible mechanism for changing Earth’s gravity as drastically as you want, and there’s no reason it’s even necessary. Please take this discussion to your own websites. We stick to real physics here.
In azdharchid pterosaurs, there is a very specific, constrained size relationship between the delto-pectoral crest, the coracoid flange, and the torso size. Since all three are preserved in Quetzalcoatlus species and the Quetzalcoatlus northropi delto-pectoral crest is also preserved intact, the size of the northropi torso can be approximated to a reasonable degree of confidence. The average distance from notarium socket to acetabulum in Q species is just over 12 inches. So, in Q northropi it is roughly about 25 or 26 inches. In short, the animal is nowhere near the volume of a giraffe and the weight is nowhere near 700 kg. 150 kg is a more probable approximation with fat animals (fueled up prior to travel) perhaps reaching 200 kg. I love Mark Witton’s sketch of a big azdharchid, himself, and a giraffe standing together, but his illustrated azdarchid torso has about twice the linear dimensions that the living animal did, and perhaps 6 or 7 times the volume. One should not base a mass estimate on that illustration — Mark didn’t.
The quad launch was first described during a talk that Paul MacCready and I gave at a Conference in late February, 1999. Launch required an acceleration of roughly 4.5 g’s, well within the capability of the front legs with the animal achieving flight speed before the front feet (hands) left the ground.
Dear Jim Cunningham,
I’m afraid your conclusions are from fairyland. Lets take them one at a time:
1. All your references to the Q.n torso indicate a much smaller creature than has hitherto been explained. The one figure you don’t mention is the 34ft wingspan. There is simply not enough volume in your torso to handle the massive musculature which flapping such a huge wing would need. 20% of body mass is the usual rough figure for flight muscles. 20% of 200Kg is 40Kg. Your torso is apparently the size of a small dog. How to you wrap 40Kg of muscle around a Labrador’s rib cage?
(A hang glider has about the same span/area as Q.n is supposed to have. I can tell you that the muscle mass to move that lot through the air is eyewateringly huge. I know, I spent years flying them.) Even 40Kg of primary flight muscles just wouldn’t cut it.
2. If Mark Witton didn’t base his drawings on the calculations of mass, why was he drawing pictures in a scientific journal instead of for Walt Disney? Mark too has this idea that the Qn torso was only 65cm from Delto-pectoral crest to acetabulum (why don’t you just say from shoulder to hip? Or doesn’t that impress people quite so much.) That is less than the chord of the wing itself.
3. The quad-launch hypothesis is just not feasible. (I thought Chatterjee invented it?). For anyone brought up with flying machines of any sort, the idea is just silly. This is where it is easy to fire off a load of maths and make it sound like science. We are talking here of a 200Kg creature with a 34ft wingspan. With a wing loading over 25Kg/m2 it would have a stall speed of about 30mph. Stall is also the minimum flight speed less the intermittent thrust vector from a flapping wing. So you are saying that 4.5g launch thrust gets a 210Kg creature from 0-30mph in twice the length of its humerus – about 4.6m? OK – an Olympic sprinter using starting blocks (to stop his feet skidding backwards) can achieve 1G initial acceleration averaging to about 0.57G over 5m (his second leg needs time to move forward and down ready to give its own push once the first leg has finished pushing). How did Q.n’s toes and fingers allow even 1g into the ground surface without skidding and scrabbling?
So, Qn needs to move 210Kg of mass through 4.6m at about 45 degrees to the horizontal and attain sufficient airspeed to allow it to unfurl its wings, spread them out above itself against the airflow, and then start to push against the air in order to start the first downstroke. My maths tells me that it would need a push force of about 2g horizontally and 2g vertically. It is just possible to imagine a modern bird doing this, but most of it’s thrust would be coming from its (already flapping) wings, not from its legs. So the whole idea is totally preposterous and does nothing for science – although it’s great for cartoon animations. Superman and Spiderman could launch like that, I know because I too have seen the films, so why not Q.n?
PS. Did you know that the maximum jump-height recorded for a Red Kangaroo is 2.5m. Clearly Qn could beat this by over 100% with its wings shut.
I am permanently closing comments on this post, because the commenters are refusing to abide by my commenting policy. I have said repeatedly that this blog is no place for debating your various “theories”, and things have veered very far off-topic from the original post. (Refresher: the post was about why we can be very sure Earth’s gravity didn’t change drastically over the past 65 billion years. It was not about mechanisms for changing gravity, or about pterosaur flight, or anything of that nature.) Go continue your petty and rude arguments on another website.
Powerful telescope enabled detailed study of gas
Using the powerful Australia Compact Array Telescope, Dr Bannister and colleagues were able to study the gas cloud in more detail as it passed in front of a quasar called PKS 1939-315 in the constellation Sagittarius.
"In our new data instead of just two channels, we have 9,000 channels," Dr Bannister said.
"We saw two bumps in the data — it first got brighter for a few days, it then became much fainter before getting brighter again and finally going back to normal."
The optical light from the quasar did not change while the radio lensing took place, indicating that optical surveys for these events would not detect them.
The authors estimate the lens is about the size of the Earth's orbit around the Sun and lies approximately 3,000 light-years away.
The new observations have allowed Dr Bannister and colleagues to develop their first estimates of the clouds' shape.
"This means we're able to start ruling out different geometries for these objects — such as solid balls of gas or bent sheets of gas. It's like going from black and white to colour," Dr Bannister said.
There are still a couple of geometries that Dr Bannister and colleagues are looking at, including sheets of gas seen edge-on or hollow noodle-like cylinders.
"Another possibility involves lumps of gas shaped like a hazelnut and comprising a spherical shell of plasma surrounding a core of cooler neutral gas, with gravity providing the confinement to keep the cloud together," he said.
"These things are all over the Milky Way and comprise a fair proportion of the galaxy's overall mass."
Resist and Bite
First, this was created in mobile, so apologise in advance.
0.1 Light Years outside Human Colonial Station Leeroy
Artillery Officer Evtrc: Sir, Bio readings indicate less than ten mammals left on the station. The pathogen deployment was successful.
Captain Vertil: Good, begin boarding and secure the command center. I want a comms officer extracting data within 10 [approx. Half hour]. Oh, and send 3 detachment to hunt down possible survivors.
Evtrc: places minor hand over heart in a salute Understood.
Four hours Later Command Center
Vertil: What do you mean that they aren't reporting in? I sent 150 Thardcts to hunt less than 10 humans. Any one of them should be able to kill all of the survivors. So how is it the first detachment lost over half it's soldiers, and the other two are GONE.
Comms Officer Fritcl: Reports from the first detachment say that every food storage area was trapped. As were the metallic storage. And the emergency respirators. And the fuel depots. Its the same as the command center. Computers are wiped, or destroyed, doors are jammed, everything that can possibly be destroyed is. The worst injuries came when the morgue was found. The soldiers discovered the missing fuels the most difficult way. I believe we can assume the residential and medical areas are no better.
Vertil: send the remaining 10 detachments. Brief them on what the first discovered, the find the missing two. Make sure the demolition squads are in front. I don't want anymore casualties.
Fritcl: Captain, we have found the cause of the deaths in the industrial complex. They were hiding in the service bot tunnels.
Vertil: Good, bring the group to me. I want to execute them myself.
Vertil: where are the rest? I told you to bring all of them.
Vertil: So your telling me that a single human managed to Murder over 80 trained soldiers by themself, and evaded capture for 3 [approx 2/3rds of a week] alone.
Fritcl: Yes. And the incidents in the residential and medical areas continue. So this isn't the only one.
Vertil looks down at the human, and speaks slowly to make sure the translator is clear.
Human. If you tell us where the others are. Then you will die painlessly.
Junior Engineer Clarke: Back on Earth. During the worst war in our history, my ancestors had a saying. Resiste Et Mords. I'll go to hell before I tell you anything.
Every head in the command center snapped to the human whoɽ just dropped through a ceiling tile.
Vertil: So you finally stopped hiding. Good. Your death will be slow human. We already have the other four.
Former Head of Security Tayna: So you're lying snakes to the end. There were only three of us. But that's not why I'm here. Iɽ like to announce your free, one way tickets. To hell. Goodbye.
Before anyone can reach her, she squeezes a small device in her hand. Then all is lost in the explosion as the station breaks apart.
This is my first time posting here, so I'll happily take constructive criticism. Sorry for the format, but there's only so much you can do on mobile.
Galileo, Stevin, and de Groot: one, Aristotle: cero
Dethroning Aristotle was a challenging task. He was undoubtedly a genius: his ideas prevailed for centuries, and many are still valid. Even Galileo, Stevin, and de Groot’s experiments were not good enough to present a general principle for the falling things.
For their principle to stand firmly, scientists needed to prove that the atmosphere was the cause for things like feathers, paper, and other objects disobeying them.
However, technology sooner or later came to the rescue. Today, we use vacuum chambers to get rid of the air or even repeat Stevin and de Groot’s experiment on the Moon to check that they were right.
Spectacular test on the Moon
In 1971, Apollo 15 astronaut David Scott descended from their spacecraft on the Moon with a hawk feather and hammer in his hands.
While he was being filmed by his partner, he simultaneously dropped both: the feather and the hammer. In the video below, you can see how the two objects fall simultaneously to the lunar soil, causing Commander Scott to burst into glee. “How about that?” he exclaimed.
An enormous vacuum chamber
In another breathtaking experiment, physicist Brian Cox set up the falling bodies experiment in the largest vacuum chamber ever built. The vacuum is achieved by pumping thirty tons of air out of the huge room.
Laboratory technicians raise a handful of feathers and a bowling ball to the ceiling of the chamber. When the vacuum is complete, the bowling ball and feathers are released simultaneously, and voilà —they all fall perfectly in unison.
The most recent experiment was done last year when scientists demonstrated Galileo-Stevin-de Groot’s principle with individual atoms.
Peter Asenbaum and collaborators at Stanford University launched clouds of different isotopes of rubidium atoms in a tube nine meters high under a vacuum. Isotopes are elements with the same amount of protons but different amounts of neutrons, making the difference in mass.
With this experiment, they corroborate once again Galileo-Steven-de Groot principle of falling objects.
Undoubtedly, Stevin, de Groot, and Galileo were right.
Today, we know from Einstein that free-falling objects behave that way because gravity disappears for them. But this is a subject for another time.
How Noniridescent Colors Are Generated by Quasi-ordered Structures of Bird Feathers
We investigate the mechanism of structural coloration by quasi-ordered nanostructures in bird feather barbs. Small-angle X-ray scattering (SAXS) data reveal the structures are isotropic and have short-range order on length scales comparable to optical wavelengths. We perform angle-resolved reflection and scattering spectrometry to fully characterize the colors under directional and omni-directional illumination of white light. Under directional lighting, the colors change with the angle between the directions of illumination and observation. The angular dispersion of the primary peaks in the scattering/reflection spectra can be well explained by constructive interference of light that is scattered only once in the quasi-ordered structures. Using the Fourier power spectra of structure from the SAXS data we calculate optical scattering spectra and explain why the light scattering peak is the highest in the backscattering direction. Under omni-directional lighting, colors from the quasi-ordered structures are invariant with the viewing angle. The non-iridescent coloration results from the isotropic nature of structures instead of strong backscattering.
A short, stocky, long-lived race, dwarves heavily value tradition. One of the most prominent traditions is the Quest for the Sky, and while some believe it fulfilled, others feel it will not be complete until they find a new homeworld for themselves. They are largely concentrated in Absalom Station or on dwarven star citadels.
- Good Old Ways: With long lives and strong traditions, dwarves are very slow to change their way of life.
- Long-Lived: They can live several hundred years before dying of old age.
- Our Dwarves Are All the Same: Very standard dwarves that are short, stocky, conservative and traditionalist, live in a clan-based society and have an affinity for mining and technology. They no longer live underground though, as Golarion is gone.
Elegant humanoids with a long lifespan, the Gap hit them harder than most. With vast swaths of their population missing the majority of their memories, many elves became convinced that they had been betrayed during the Gap. Unable to determine who the guilty party could be, if there even was one, the elves withdrew to Sovyrian on Castrovel and rapidly developed into a reclusive and xenophobic society. Elves deeply value magic as the continuation of their ancestors' work and many of the elves seen outside their own kind are seeking fragments of lore or magical items.
- Hidden Elf Village: Following the Gap, elves have mostly retreated to their ancestral homeland of Sovyrian in Castrovel and isolated themselves from the rest of the universe.
- Long-Lived: Even more so than dwarves, with lifespans capping out near a thousand years. Yes, this means that many Elves lived though the Gap, and they are not happy about that.
- Our Elves Are Different: Elves are still the same lithe, long-lived, whimsical and passionate race of humanoids with characteristic pointed ears that live in relative isolation with other races. They were also the hardest-hit race by the Gap, and have adopted xenophobia as a result of that.
- Pointy Ears: Pointed ears are a trademark of elves that set them out from humans.
- Rubber-Forehead Aliens: They're native to Castrovel and look like humans with pointed ears.
Emigrants first of the First World, then of Golarion, Gnomes are a varied people. There are two ethnicities of gnome. Feychildren have wildly colored hair and skin, but are forced to constantly seek new experiences to maintain their vibrancy or else undergo the Bleaching. Bleachlings are descendants of those who survived the process, lacking the wild personalities and appearances of their feychildren kin. Gnomes are also the only outside race welcomed by the elves of Castrovel for reasons unknown.
Interracial children of elves and humans. With no one heritage, they often feel like outsiders and band together with others who feel the same way or those to whom humans and elves are so alien they wouldn't realize something was strange. Half-elves are welcomed in Sovyrian, though they are considered second-class citizens, and Absalom Station takes them as readily as it does any other.
- Half-Human Hybrid: The vast majority of half-elves are half-human on the other side, to the point that they have both the elf and human subtypes.
- Non-Human Humanoid Hybrid: A growing number of half-elves on Triaxus are half-ryphorian instead of half-human. They are oddly similar to their human-born counterparts, however.
- True-Breeding Hybrid: It's not particularly common, but half-elves breed true and a number of half-elven settlements have sprung up around the Pact Worlds. The result is that some half-elves are quite far removed from their human, elven or ryphorian ancestors.
Interracial children of orcs and humans. Generally shunned by society, most half-orc either seek positions where the fear they cause is an asset, group with others shunned by society, or push beyond society to break ground for colonies.
- Determinator: They can keep going for one round after being brought below zero hitpoints.
- Half-Human Hybrid: Half human, half orc. However, since it's mentioned that because orcs were almost entirely contained to Golarion and Golarion is gone, most half-orcs since the Gap have been the result of true-breeding between other half-orcs.
- Slave Race: Not technically but for all practical purposes. The majority of half-orcs and orcs live on Apostae as second class citizens with no say or representation on political matters at all, serving the drow rulers of the planet as manual laborers or mercenaries.
- The Character Operations Manual introduces a variant that actually were slaves under the Drow, and thus have different stat bonuses than freed Half-Orcs.
A diminutive race known for their even tempers and cool heads. Most halfings eschew enhancements, considering halfling biology to be pretty much perfect already. Though they make good spokesmodels or entertainment stars, a long history of enslavement means few will lock themselves into commitments.
- Born Lucky: As always, they're naturally lucky.
- The Pollyanna: Their cheerful optimism is often kept even when in danger, making them seem fearless in comparison to other races.
- Retired Badass: Halflings are practically genetically predispositioned to become this, most of them having a phase as bold daredevils in young adulthood before mellowing down.
- Slave Race: They've had a history of being such, and distrust many races as a result.
My uncle had "brain bubbles"
My mother called me a few days ago. She was crying, and reminded me that it was her brother Brian’s birthday. I was surprised to hear that name she hadn’t talked about him in so long that I’d completely forgotten what happened. When I told this story to my buddy, he mentioned that Reddit loves creepy government stuff – so here’s the tale of my family’s dark mystery. I’ll tell you what I know first, and then I’ll tell you how I know.
My uncle Brian was a “scrubber” for a private company contracted with the US government. His job (or the job of his entire team, rather) was to retrieve or destroy secret, top-secret, and alleged “above-top-secret” data from sunken military vessels. This included anything from documents, storage drives, cargo, weaponry, dog tags/identification cards, and corpses. He would also scrub identifying marks on ships, strip indicators of country of origin, and salvage valuable parts of the craft. His duties were not limited to these, but these are the most interesting and relevant.
Brian performed deep sea dives between 1969-71, then again from 1980-81. We don’t know much about his life between those two periods, but we do know that he was stationed at a “training facility” somewhere in the arctic circle, probably Greenland or Canada. During that time, he only visited his home in Arizona for 6 weeks per year, and was forbidden from doing all kinds of weird things. He was not allowed to purchase office supplies or typewriters, could not spend money at all except with a checkbook issued to him by his employer, could not go into a bank for any reason, could not handle cash, could not go to large gatherings or drink alcohol, etc. They wouldn’t even let him smoke cigarettes. He was forbidden to write anything down and therefore would never handle a pencil, couldn’t talk about his job, and refused to even touch a phone, with one exception.
Brian had to call a phone number every six hours, regardless of the time of day. He would wake up in the middle of the night to make the call, which always pissed off his wife. Whenever he made that call, he always spoke casually, as if talking to an old friend, and had conversations that never amounted to more than idle chit-chat. I only heard these calls once in my life, and only in retrospect did I realize that they were heavily coded. What he was actually saying, we will never know. Even when someone called for Brian, he wouldn’t take the phone he would only touch it or speak if he dialed the number. I have never seen such a paranoid person in my life, but in my young age, I found his behavior harmless and amusing.
My uncle mysteriously disappeared in 1999, when I was twelve years old. I had only met him twice, and by that time he was retired. I was too young to remember him the first time we’d met, but the second occasion I actually tried to block out – and pretty much have, until this conversation with my mom.
When we visited him for a week in Phoenix, he was glum the entire time. The man was singularly unfriendly, and appeared scarcely aware of anything but his own private thoughts. He was more pensive and withdrawn than anyone I’d ever known, as if he’d retreated entirely from this planet and left a functioning body behind. He looked over his shoulder all the time, even on the couch, and always watched the rear-view mirror when my mom drove us out to dinner. I remember him constantly doing weird things, like inspecting the light switches in his own home, unscrewing the little plates and poking around, then putting them back on. He looked up in the air each time he walked outside, as if he expected a brick to fall on his head, or maybe a helicopter to snap a photo of him. He only ever spoke in short and stilted sentences, cautious not to divulge anything that could get him into trouble. Brian seemed like he had the weight of the world on his shoulders, and a flood of confessions just behind the dam of his teeth. I found myself wondering about him each night as I tried to fall asleep.
One night during that visit, Brian snapped. I don’t know what caused it, but he had a massive freak-out and started acting like he was on hard drugs. In the middle of a normal conversation on the couch, he started shrieking about how he was “sick of all the games” and didn’t “wanna be a gerbil anymore.” To my mother’s horror, he lunged at me and tried to strangle me. He kept screaming to my mom that he was going to “twist the head off, show you all the circuits!” and went on and on about how there were cameras in my eyes and microphones in my ears. He bit me, and when he saw that I bled, he snapped out of the episode and burst into tears.
My mom tried to call 911 from the house phone, but it wouldn’t connect. She frantically dialed the number on his barren fridge, and a woman answered. My mom told her that Brian was acting crazy, and said she needed police and an ambulance. The woman told my mom that she’d phone Brian’s doctor immediately, and that everyone should just sit tight. (I refused to go to the hospital anyway I’m a lifelong emetophobe and hospitals make me nauseous.)
In less than an hour, a man showed up at the door. He called himself “Doctor S.” The doctor was dressed in ordinary slacks and a button-down shirt, and had a clean shave. I remember noticing the roughness of his hands when he shook mine. He was big, but too well-spoken to be some bruiser. I have trouble explaining what I mean, but the plainness of his appearance and the calm of his demeanor felt very menacing to me, like he was about to murder every person in the house, Patrick Bateman-style. The thing I remember most about him, however, was that he carried the acrid stench of chemicals, as if he’d been varnishing wood or something.
The doctor had a quiet conversation with my uncle on the back patio, and then he politely excused himself and left. He told my mom and I that “Brian is going to be fine, he just needs a bit of rest. I’ll order a prescription and you can pick it up for him tomorrow.” When my mother asked if it was dangerous to be alone with Brian, the doctor just laughed and said “Not anymore. I promise.” He squeezed my shoulder and walked away.
Two things really disturbed me about “Doctor S.”’s visit. The first was that between hello and goodbye, the man wasn’t there any longer than four minutes. What could he possibly have said to Brian in that amount of time? And second, when I ran upstairs to watch the doctor drive away, he didn’t get into a car. He literally walked out of the neighborhood.
Brian immediately seemed better after his meeting with the doctor. He apologized to me, and ate dinner with us. He was in much higher spirits, like he’d been relieved of every burden he carried.
My mom and I slept in the guest room with the door locked that night, simply because we had no idea what to expect from him. Brian was like his precious light switches: on or off, and nothing in between. But in the middle of the night, I woke up to my mother shouting. The house was dark, the patio door was wide open, and Brian was gone. He didn’t take anything with him – not his shoes or his checkbook or watch. His car still sat in the garage, and keys on the counter.
We tried to call the number on the fridge, but the line was disconnected. The phone wouldn’t dial out at all.
Early the next morning, a bunch of men showed up to the house. They took all Brian’s possessions away in boxes, and asked my mom and I a ton of really strange, nonsensical questions – things like, “Did Brian ever tell you his favorite color?”
“What food does he hate the most?”
“What is your earliest memory of him?”
“Was he right or left-handed?”
The interrogation left us baffled. I was really confused by all of this, but my mother was downright mortified. No matter what answers she gave, they always doubted her, and told her she must be wrong, and gave some ridiculous explanation as to why. On the other hand, they never questioned a single thing I said. I still don’t understand what the point of all that was.
Almost a year later, after the shock of his disappearance began to settle into a dull pain, my mother decided to sell her car. Under the floor of the trunk, tucked into the spare tire, she found a VHS tape. It was from Brian. He probably left it there while we were asleep.
In it, Brian was standing way out in the desert somewhere. He looked a few years younger, and appeared to have not slept in days. He described the nature of his work to my mom, and some of the things he’d seen and done. I pieced together everything I know about him from this tape and some conversations between my mom and Brian’s ex-wife.
I haven’t seen the tape since we found it, and I’m sure my mom got rid of it, as Brian instructed. But here are the things I remember best – the weirdest and scariest things he found while working sunken ships and submarines:
-Rooms that remained pressurized, where people appeared to live for weeks after the submarine sank. Some of the sailors appeared to have lost their minds and wrote all over the walls or killed each other
-Loud banging sounds on the hull and in passageways. These wrecks were mostly from WWII and the Cold War, some Vietnam – so years or decades old. But Brian swore he heard “SOS” in Morse code on more than one occasion. He even claims he once heard “LEAVE”
-Frozen bodies that looked mummified, suspended in the wrecks with smiles on their faces (the skin freezes and flakes off, revealing a ‘grin’)
-The body of a young woman who appeared to have died much more recently than anyone else on the ship. She was wearing a flowing white dress, and “looked like an angel” when Brian found her. She wasn’t desiccated like the other bodies her skin was pristine, despite being locked in a British submarine that sunk in the 1940’s and now lays at the bottom of the North Sea
-Strange things on Soviet ships. Human experiments, fetuses in bottles, remains that looked both human and animal, cages, chains, extensive prison networks in the bowels of one nuclear-class icebreaker in the Arctic, etc. Brian claims he found the body of what looked like a baby, floating in a laboratory, but its limbs were 2-3 feet long and dangled together like a dead wasp’s. When he moved it, it broke apart and dissipated in the water. Very few bones at all
-Brian talked of discovering a passenger jet that had never been reported missing. It crashed into the ocean and sank. All of the corpses were still buckled into their seats. The unusual thing was that the jet had sunken next to an old ship, and the corpses on the jet all wore dog tags that were traced to that ship. It was as if someone had played a practical joke by moving the dog tags, but my twelve-year-old mind imagined the corpses of the ship walking across the sea floor and buckling themselves into the crashed jet, hoping it would take them back to their families
-Scrubbers going mad in the depths. Two of Brian’s friends went missing during a dive off the Alaskan coast. One of them was found sealed inside a room of the submarine they were exploring, a door that could only be locked from the outside. He was nearly dead of hypothermia, and swore that a woman without a face had put him there. The other managed to remove a small part of his helmet, instantly killing himself because of the pressure difference
-There’s more, and I’ll try to remember/ask my mother if anyone is interested
In the years after Brian’s disappearance, strange men visited me once in a while, always asking about Brian. They found me in random places and always asked random questions. They were always polite, but never identified themselves. No matter where my mom and I moved, they found us. One time, a substitute teacher showed up to my high school biology class in Senior Year and gave the standard lecture, but at the end of the day, he asked me if I had any relatives who worked in the government, and if I could remember what my uncle’s favorite color was. On another occasion in college, my then-girlfriend/now-fiancée and I went to a bar for a friend’s birthday, and the bartender kept trying to serve me alcohol (I don’t drink) and then asked me if I’d ever consider moving to Phoenix. He told me his buddy Brian used to live out there, and asked me if I’d ever been scuba diving. At the end of the night, he asked how my mother was doing – and used her full name.
Most recently, while jogging the forest trail near my house in California, a guy on a bicycle stopped me and told me I looked just like a guy he once knew – Brian, a dude he met in the Navy. He mentioned that they lost touch, and said, “Last I heard, he was out livin’ in the desert or somethin’, far away from the ocean. He hated the ocean.” I replied sarcastically that he probably went to Phoenix, and the guy’s expression went cold as a dead fish. He said, “That’s right. He’s happier there, I’m sure of it.” Then the man rode off. The one thing all these people had in common was that they reeked of chemicals, just like “Doctor S.”
Brian’s ex-wife Jill once told me “Your uncle had brain bubbles,” and told me that the crazy things he’d say were the result of brain damage from diving. The mixture of gasses, pressure, and tight spaces, coupled with other stressors of the job could certainly do real harm to a person’s mind. But then again, Jill also worked in the government that’s how they met, and after Brian disappeared, she acted like she barely remembered him at all. It was almost as though she wanted me to dismiss him as a nut job.
Feathers and filaments of dinosaurs, part II
In the previous post we looked at the feathers and filament-like structures that covered the bodies of coelurosaurian theropods. While basal coelurosaurs - compsognathids and tyrannosauroids - possessed filament-like 'Stage 1' structures alone, members of Maniraptora (the coelurosaur clade that includes oviraptorosaurs, therizinosauroids, birds, deinonychosaurs and, probably, alvarezsaurids) possessed indisputable vaned feathers. That is, complex feathers that had a distinct central rachis with vanes on either side composed of parallel barbs. What is surprising is how luxuriant some of this covering seems to have been, and on how much information we now have about the arrangement of feathers on the bodies of these dinosaurs.
Though it has been suggested at times that vaned feathers simply must have evolved for flight, the phylogenetic distribution of these structures currently indicates that they first evolved in flightless maniraptorans and were only later exapted by long-armed maniraptorans for use in locomotion. Of course a well-known minority opinion, best known from the writings of Greg Paul, is that feathered maniraptorans are secondarily flightless and descend from volant bird-like ancestors. While this remains possible it lacks support from the fossil record, though that may or may not mean much. I want to avoid discussion of this area here and will cover it another time [image of sinornithosaur above borrowed from here].
Feathered fingers and hand flags
Exactly how feathers were arranged on the arms and hands of both basal birds and non-avian maniraptorans has long been unclear, and both non-avian maniraptorans and archaeopterygids have conventionally been depicted as possessing unfeathered fingers. However, this just doesn't work given that the second finger is needed to support the remiges* that we now know were present throughout maniraptorans: this is what it does in living birds. Derek Yalden's 1985 study was important in showing exactly how the remiges would have grown off of the first and second phalanges of the archaeopterygid second finger (Yalden 1985) [adjacent image shows Yalden's reconstruction of Archaeopteryx, with a modern magpie's wing above it]. A check of the literature on archaeopterygids shows that this configuration has been widely recognised (Bohlin 1947, Rietschel 1985, Griffiths 1993, Stephan 1994, Elzanowski 2002), though rarely brought to the attention of artists for some reason.
* Remiges are the large feathers of the forelimbs (singular remex). The large feathers that grow from the tail are termed rectrices (singular rectrix).
Incidentally, there has been some minor historical disagreement over exactly how many remiges were present in archaeopterygids (there were most likely 11 primaries and a tiny distal 12th one, and at least 12 secondaries), and also about how the hand claws were arranged: I agree with Elzanowski (2002) that the claws were directed perpendicularly to the palmar surface in life, and rotated anteriorly in most (but not all) specimens during burial. It has also been suggested on occasion that the fingers of archaeopterygids and other feathered maniraptorans were united in a single fleshy 'mitten' as they are in modern birds, and hence unable to be employed in grasping (Martin & Lim 2005). Given that the interphalangeal finger joints of archaeopterygids appear suited for flexion and extension, and that the third finger apparently remained free and flexible in birds more derived than archaeopterygids (Gishlick 2001), this is unlikely to be correct it's based on a depression in the sediment that Martin and Lim identified around the bones.
[Image above of excellent Caudipteryx skeleton from here].
Like those of archaeopterygids and modern birds, the remiges of non-avian theropods would also have been attached to the phalanges of the second manual digit as well as to the metacarpus and ulna, and indeed we can see this in the fossils. It's the case in the sinornithosaur NGMC 91-A and Microraptor (remember that, while we now have more feathered theropods that we did just a few years ago, we still only have soft-tissue preservation in a tiny minority of taxa). Surprisingly, in Caudipteryx the remiges are restricted to the hands alone, and don't extend from the arm [see image below]. They seem to have formed little 'hand flags' that are unlikely to have served any function other than display. Were 'hand flags' unique to Caudipteryx, or more widespread? Were all oviraptorosaurs like this?
If you're wondering: yes, Caudipteryx (currently represented by two species, C. zoui Ji et al., 1998 and C. dongi Zhou & Wang, 2000) is an oviraptorosaur and possesses a suite of characters unique to this group. It is not a member of Aves, despite the efforts of some workers to make it into one. In contrast to later members of Oviraptorosauria, it possessed premaxillary teeth, had proportionally elongate hindlimbs and lacked a claw on its third manual digit. For a previous post on oviraptorosaurs see Luis Rey and the new oviraptorosaur panoply, and for a discussion of tooth function in Caudipteryx and other feathered maniraptorans see The war on parasites: an oviraptorosaur's eye view.
Given that several maniraptoran lineages were clearly predatory and, given the morphology of their manual claws, fingers and wrists, presumably in the habit of grabbing at prey with their hands, wouldn't the remiges have interfered with the use of the hands in predation? The short answer is no. The long answer - taken here from a paper Alan Gishlick published on forelimb function in Deinonychus - is 'feathers on the hands would not have greatly impeded the use of the hands in predation. Because the feathers are attached at an angle roughly perpendicular to the claws, they are oriented tangentially to the prey's body, regardless of prey size' (Gishlick 2001, p. 315). It is important to note here that theropod hands appear to have been oriented such that the palms faced medially: that is, they faced inwards, and were not parallel to the ground as used to be imagined [adjacent image of Microraptor wing from here].
However, feathering would have interfered with the ability of the hands to bring a grasped object up toward the mouth given that extension of the maniraptoran wrist would have caused the hand to rotate slightly upwards on its palmar side. If both feathered hands are rotated upwards and inwards at the same time, the remiges from one hand would collide with those of the other. For this reason, maniraptorans with feathered hands could grasp objects, but would probably not be able to carry them with both hands. Senter (2006) has proposed that dromaeosaurids and other maniraptorans may have solved this problem by clutching objects single-handedly to the chest. Feathered hands would also have restricted the ability of the hands to pick objects off of the ground, given that the feathers extend well beyond the ends of the digits.
It remains possible that some maniraptorans lacked remiges on their fingers, but the only evidence we have in fact indicates the contrary. It's recently been argued that the particularly long second digit of the oviraptorosaur Chirostenotes was used as a probing tool, locating and extracting invertebrates and small mammals and so on from crevices and burrows (I have a post planned on this subject - it's to be called 'The probing guild' - and will talk more about this subject then). It seems highly unlikely that a digit that is regularly thrust into small cavities would have had feathers extending along its length, so either Chirostenotes didn't probe as proposed, or its second finger was unfeathered, unlike that of Caudipteryx and the other feathered maniraptorans [adjacent Microraptor image from here].
Given the problems that the feathers might have posed for clutching and grabbing prey from the ground, we might also speculate that some of these dinosaurs deliberately removed their own remiges by biting them off. Some modern birds (notably motmots) manipulate their own feathers by biting off some of the barbs, so this is at least conceivable, albeit totally speculative of course.
I wanted to cover hindlimb and tail feathers too, but. another time. Come back soon!
Bohlin, B. 1947. The wing of Archaeornithes. Zoologiska Bidrag 25, 328-334.
Elzanowski, A. 2002. Archaeopterygidae (Upper Jurassic of Germany). In Chiappe, L. M. & Witmer, L. M. (eds) Mesozoic Birds: Above the Heads of Dinosaurs. University of California Press (Berkeley), pp. 129-159.
Gishlick, A. D. 2001. The function of the manus and forelimb of Deinonychus antirrhopus and its importance for the origin of avian flight. In Gauthier, J. & Gall, L. F. (eds) New Perspectives on the Origin and Early Evolution of Birds: Proceedings of the International Symposium in Honor of John H. Ostrom. Peabody Museum of Natural History, Yale University (New Haven), pp. 301-318.
Griffiths, P. J. 1993. The claws and digits of Archaeopteryx lithographica. Geobios 16, 101-106.
Martin, L. D. & Lim, J.-D. 2002. Soft body impression of the hand in Archaeopteryx. Current Science 89, 1089-1090.
Rietschel, S. 1985. Feathers and wings of Archaeopteryx, and the question of her flight ability. In Hecht, M. K., Ostrom, J. H., Viohl, G. & Wellnhofer, P. (eds) The Beginnings of Birds - Proceedings of the International Archaeopteryx Conference, Eichstatt 1984, pp. 251-265.
Senter, P. 2006. Comparison of forelimb function between Deinonychus and Bambiraptor (Theropoda: Dromaeosauridae). Journal of Vertebrate Paleontology 26, 897-906.
Stephan, B. 1994. The orientation of digital claws in birds. Journal fur Ornithologie 135, 1-16.
Yalden, D. W. 1985. Forelimb function in Archaeopteryx. In Hecht, M. K., Ostrom, J. H., Viohl, G. & Wellnhofer, P. (eds) The Beginnings of Birds - Proceedings of the International Archaeopteryx Conference, Eichstatt 1984, pp. 91-97.
Mysterious spherical mass of feathers (Reddit) - Biology
But . why? Is gravity really a force that way?
Yes, the force of gravity increases exponentially the closer to the center of mass you get.
Now this is a pretty boring rocket with no windows, so I don't notice the very large planet that is coming up in front of my rocket. To an outsider, my rocket will "swing by" this planet, accellerating my rocket in the process. But me inside? I won't feel a thing. In fact I won't be able to detect that I am in the presense of a planet at all, as I am still free falling through the "curved space" around the planet.
This is not true. If you are oriented with your feet closer to the planet, your feet would experience a stronger acceleration than your head. The difference is extremely minute for planetary objects, but it still exists, and with a black hole, this difference in acceleration is magnified by a factor of billions.
I believe it's quadratically.
This implies that gravity is a force. It is my understanding that this is not the case. Mass tells space how to bend, and space tells mass how to move. Bent space can't "grab on" to you the same way as you can grab on to my arm - as I understand it at least.
So yes the space around my feet is more curved than the space around my head, but why are my feet not curving along with the space they occupy?
This implies that gravity is a force.
Gravity is a force. I wouldn't get too caught up in how it "bends" space. It's not helpful for understanding things like this.
Mass tells space how to bend, and space tells mass how to move.
In this case, the space is "bending" a lot more near your feet than your head, so space is "telling" the mass in your feet to move much faster than your head.
I think the main reason I'm having trouble with this is that to me, when space bends, it also bends the matter inside the space. Like when you spill a drop of blue paint into a bucket of white paint, and stir the whole thing around a bit. The blue droplet will become a long smear, but it won't "break" at any point. You should be able to "stir backwards" until the blue droplet looks completely like it did when you dropped it.
Does the droplet "feel" this stretching out if it's the entire spacetime around it and "inside it" that bends and stretches?
Does the droplet "feel" this stretching out if it's the entire spacetime around it and "inside it" that bends and stretches?
But you aren't a single point in space. The spacetime around your body is different depending on how close that body part is to the black hole. It the difference in the "bending and stretching" of space that also pulls you apart.
The blue droplet will become a long smear, but it won't "break" at any point.
That's analogous to spaghettification.
when space bends, it also bends the matter
That is only to an outside observer. From the object's point of view, it is still in its original shape. You would feel this bending.
Consider this: are planets in orbit moving in a circular(ish) path around the sun?
The answer is no, all orbiting objects are moving in a straight line at a distance determined by their velocity. Since the sun's gravity is curving spacetime itself, the straight path curves around the sun, becoming a circle (ellipse if you want to get technical).
Straight path in uncurved spacetime looks like a straight line
Straight path in curved spacetime looks like a curved line (curvature depends on distance to and mass of central object)
Edit: You're mixing too many concepts together and preparing a fusion recipe spaghetti :P
This implies that gravity is a force. It is my understanding that this is not the case. Mass tells space how to bend, and space tells mass how to move.
Ok, if you want to get really technical, then yes, gravity is not a "force." Gravity is the result of spacetime's curvature.
Bent space can't "grab on" to you the same way as you can grab on to my arm - as I understand it at least
Actually, it can. It's like how light waves get redshifted (i.e. get longer) as they travel through space because spacetime is expanding.
Reading through your replies, you aren't quite understanding the "gravity is not a force" idea. Gravity itself is the curvature of spacetime, yes, but it can produce forces in the presence of matter (F = m * g). The part you are missing is that gravitational fields are not noticeable only on sufficiently short distances or timescales. If you are in a weak field for a long enough time or over a large enough distance, you absolutely would be able to detect the presence of the gravitational field. You can do this with an experiment. Place two balls a fixed distance apart as you travel through the gravitational well and measure their distance with a laser. Eventually, you would measure a change in the distance between the balls even though you are in free fall. This is because gravity tells matter how to move.
Now why does this cause spaghettification in a strong field? You kept stating that gravity should elongate you instead of ripping you apart, and you are absolutely right! However, the thing you need to add to that statement is that eventually the molecular bonds in your body can no longer withstand the elongation and will snap. This continues to happen until every molecule in your body is ripped into its constituent atoms.
Let's go back to the two balls experiment just to drive this point home. If you dropped both balls into a black hole, one where your feet would be and one where your head would be, then the ball at your feet would be pulled towards the singularity exponentially faster than the ball at your head. For the sake of argument, these "balls" are actually just points (so you can't get pedantic about the molecules in the balls). Remember, gravity causes acceleration. So bottom ball moves much faster than top ball as it gets closer.
Now let's imagine a rubber band between the two balls. This rubber band is ideal, and represents the strength of the bonds in the molecules between your feet and head. It has a finite maximum strength. Now since it has mass, and is experiencing acceleration due to gravity, it will feel a force. The force doesn't come from the gravity alone. It comes from gravity times mass. (Remember: F = m * a is still true!) So the rubber band has mass and is being elongated as the balls are pulled apart. ONCE THIS FORCE EXCEEDS THE STRENGTH OF THE BOND, IT WILL SNAP! I put that part in caps not to yell at you, but to emphasize the most important part of this entire thought experiment: Matter, even down to subatomic scales, has both binding energy and mass. Once mass times acceleration due to gravity exceeds this binding energy, it will be ripped apart.
As a final thought: If you put your blue paint analogy in a blackhole, then the blue paint would be elongated until it's constituent atoms are ripped apart. Humans snap much easier than paint though. We aren't really that elastic. Paint is.
What OP seems to be missing is that the equivalence principle only applies to point masses. A non-point mass observer in an elevator near a sufficiently warped gravitational potential gradient will notice that he/she is under the influence of a gravity well.
Strictly speaking the equivalence principal only applies for sufficiently short time and length scales, point mass or not
If the observer is not a point mass, wouldn't they need measure up to an arbitrary level of precision to determine if they are in a gravity well?
Not if the time or length scale was long enough. I recently took a graduate level relativity class, and we calculated that in Earth strength gravity it would be roughly 2 hours before you could determine with a simple experiment that you are in a gravity well. This is of course approximation, but it was enough to confirm the equivalence principle