The problem is more likely to be in the calculations than anywhere else.
earth was smaller.
The continents have fitted together into a single super-continent at least once in the geological past and will probably do so again before the Sun turns into red giant.
Nobody in their right minds suggests that the super-continent covered all of a smaller earth, but there are plenty of lunatics around peddling nonsensical pseudo-science. You swallow the denialist propaganda that claims the anthropogenic global warming isn't happening, so I guess we shouldn't be surprised that you don't gag on other - equally implausible
- twaddle.
oceans and the increased mass?
The favourite explanation for the size of our moon does involve a giant impact
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The earth would have rather more than boiling hot immediately thereafter, and IIRR the water is supposed to have arrived later in dribs and drabs, as comets from the outer regions of the solar system collided with the earth.
became birds.
(no need to fly),
The fossil record paints a different picture.
aerodynamics and
The favoured hypothesis is that some small dinosaurs evolved feathers - to keep warm - and took to running around on their hind legs. The forelegs were retained for balance and grasping, and some small dinosaurs who had happened to evolved particularly voluminously feathered fore-legs found that they could make long, silent leaps with the help of their proto-wings ...
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You certainly don't seem to know much, and you have frequently demonstrated that you can't distinguish real science from pseudo-science. There are plausible scientific theories around, but you don't seem to have studied enough to recognise them when you run into them.
The asteroid that wiped out the dinosaurs was rather large - about 10 km in diameter.
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Smaller asteroids are more numerous. The lump of rock that hit Tunguska (in Russia) in 1908 was around 50 metres in diameter, and we can expect one of those every thousand years or so.
If that one had hits a major city, it would have killed around a million people and amaged quite a lot of expensive real estate, so it's probably cost effective to keep an eye on objects in earth- grazing orbits.
The mere suggestion that we, as a civilization, would be capable of keeping this up for a millennium, or even a century, is laughable. We're far too capricious and quarrelsome. Whatever system is set up for the purpose is much more likely to be diverted to wipe out the enemy of the moment.
On a sunny day (Tue, 19 Jul 2011 00:36:37 +1000) it happened Bill Sloman wrote in :
Well those guys did their homework. You are now an expert on aerodynamics too?
earth was smaller.
OK, your keyword, well there were to few humans around back then to cause it. Yet the climate changed, Paradox?
WTF is it always bad science if it disagrees with one of your ideas? Run a self test.
oceans and the increased mass?
Yes I have read that, looked convincing too. Unfortunately the recent data from the moon satellites points to a different origin for the moon, and water may come from earth itself. There are as many theories as people almost,
became birds.
(no need to fly),
That is a very dangerous thing to go by, it works like this: If I find the Mercedes before the T-Ford, I could think Mercedes came first. Sometimes I thing those diggers have a narrow bandwidth they think in.
aerodynamics and
Yea, keep flapping your hands, maybe you will fly. Fur would have been the logical thing to keep warm, but OK, apes may evolve from humans, Obamama is a clear example.
Oh Bill, your wisdom sinks in the quicksand of your arrogance. Don't let it bother you though. Just hold on to earth, else you fall of down there,
Given a few more centuries of technical development, keeping an eye on near earth objects will probably be high-school science project. Doing something about a rock that might actually hit us would require some industrial-scale engineering, but the sort of gear that you might use to modify the orbit of a medium-sized rock isn't going to be much use for any other job.
I'd imagine lots of specific impulse from some kind of ion drive, sitting on the relevant rock for years.
Adapting the hardware to drop a rock on your neighbours wouldn't work too well - the ion beam is going to visible from quite a way away, and the waste heat from the drive would also be easily detectable. The obvious power source would be a nuclear reactor - a huge array of solar panels might be an alternative but either is likely to be tolerably visible.
Right, and the proposed enemy (presumably one of the ones excluded from the development process) will rightly see it as a potential weapon and destroy it at the first sign of trouble.
On a few fossilised bones. Paleontologists don't always agree about the way the bones they dug up fitted together back when creature was alive, and the guys that did the calculations had a few more opportunities to get things wrong in concocting their reconstruction of what the creatures looked like and how they flew.
You aren't an expert in aerodynamics, yet you felt qualified to tell us that the calculations were okay. I've had to listen to stories about how vortex shedding flow meters work, and learned enough to know that aerodynamics can be tricky.
Bad calculations are more likely than either.
and earth was smaller.
e it.
Scarcely. The ice ages represent big time climate change, and they were going on all the time that humans were evolving. The Paleocene- Eocene Thermal Maximum seems to have been an entirely natural episode of rapid global warming, driven by the sudden release of methane from methane clathrates, when a much slower warming trend got the earth warm enough to destabilise the clathrates
We could be well on our the way to engineering a similar event, and if you get your way we'll find out about it when it is too late to do anything to stop it.
Perhaps because I don't disgree with the stuff that is good science?
t the oceans and the increased mass?
ent origin for the moon,
Would you care to cite your sources? On those rare occasions when you do point us to the basis for your daft ideas, you usually turn out to have misunderstood what was being said, and this is almost certainly going to be more of the same.
Perhaps, but relatively few of them survive the peer-review process to get into the scientific literature, and some of them turn out to have been reiwed less carefully than they should have been
fly and became birds.
thers (no need to fly),
st.
Benz did invent his automobile a decade or so before Henry Ford set up the Model-T production line.
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In any event, the fossil record is a better guide than your imagination.
t into aerodynamics and
.
It's like the evolution of the eye. Creationists argue that a half- evolved eye is useless, while the world is full of creatures with rudimentary eyes that do useful things for the creatures that have them.
Gliding squirrels don't fly like birds, but they seem to get a useful advantage from just being able to glide. Maybe bats looked like gliding squirrels art some point in their evolution .
Evolutions isn't about logic, it's all about variations on what you've already got. Mammals evolved fur, some dinosaurs evolved feathers. Fur doesn't seem do much for bat's wings, but feathers do seem to work for birds.
All human beings happen to be apes - we are third branch of the chimpanzee family - so you really are talking nonsense.
nothing,
em.
It certainly isn't wise to tell a fool that he is wrong. He won't believe you, and he'll resent being contradicted. So I'm definitely not wise. I am - however - tolerably well-informed, and you are not. You will clearly see this statement as arrogant, but any other statement would be in conflict with the facts of the situation.
It doesn't - as you might have observed from other interactions in this forum.
a we have is not accurate because of changes in the
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You and John Larkin think one thing, John van Neumann
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happens to have thought something different. I think I'll continue to put my money on John van Neumann being right.
.
I imagine you might. Would you like to give us an example of how this might have worked? Most of the dates from around then depend on K-40 decaying to Ar-40, and the information collected is the ratio of Ar-39 to Ar-40 in the samples.
I'm not a philosopher, imagining how the world might be, but a student of science, retailing well-tested hypotheses about how the world got to be the way it is.
As a student of science, I'm well aware that even the best-tested hypothesis can prove to be an approximation to a better explanation. I'm afraid that you have been peddling hypotheses that not only fail to explain known facts, but actually conflict with some of them.
Any kind of philosopher - amateur or professional - would have to do better than that.
There are plenty of flightless birds even today. And parallel evolution of flight in mammals. Both will go through a phase of only being able to glide or fall more gracefully before evolving powered flight.
There are even some fish that make a passable attempt at gliding flight
- which considering the impedance mismatch between air and water is quite remarkable. Ground effect helps them a lot. And the advantage to the fish is to escape predation by coming down a long way away.
Or flightless birds that were among the first warm blooded creatures with the feathers to keep them warm. Being able to fall out of trees more gracefully and not get hurt is still an evolutionary advantage.
earth was smaller.
Are you sure you are not a flat Earther too? Kook-a-doodle-do!
Yup... being able to glide from tree to tree rather than having to ground-walk cuts your exposure to ground-dwelling predators and has definite survival advantages.
As I understand it, the current mainstream thinking in paleontology is along the following lines:
- Birds are (most probably) descended from one line of ground- dwelling theropod dinosaurs. [There's another school of thought which says that the avian line forked off from the archosaurs before dinosaurs first evolved.]
- Feathers originally evolved prior to this point.
- Many theropod dinosaurs (possibly most) were feathered (a significant number of such fossils have been found in recent years).
- Many dinosaurs had a relatively high body temperature and metabolic rate - in the same ranges as those of modern mammals.
- Dinosaurs were able to survive and breed in fairly cold climates (cold enough that the ground had permafrost in it). Hence, it appears that features probably pre-dated flight by quite a long time, and had originally evolved for other purposes (heat retention, and perhaps as a form of identification / display).
As to how some feathered theropods originally developed flight. there seem to be two schools of thought: "climbing and gliding" (e.g. as flying squirrels and lizards have done), and "running and leaping" (or "crouching down and leaping really hard" as some pterosaurs are thought to have launched themselves). I suppose it's quite possible that flight may have been developed by different species in each of these ways.
--
Dave Platt AE6EO
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And why is this interesting? We can deduce quite a lot about the wings from looking at their fossilised remains, but we have to deduce how they were used from the same fossil evidence, and the train of deduction is correspondingly longer and the accumulated uncertainties rather larger.
Take a look at the debate on the evolution of human language sometime.
The rest if my response - which you have discarded with your usual unmarked snip - made it perfectly clear that I did find the question valid, and that what I wanted to know was why you found the question interesting, since you don't actually think about this kind of stuff.
On past history, you came across it in some creationist propaganda which you failed to recognise as propaganda.
The evolutionary argument is that specialised skills - like flight and language - evolved from less specialised behaviour - like gliding and giving warning cries, but it's not always easy to find and identify the intervening stages. Creationists claim that intervening stages couldn't have existed, which is a rather bold assertion about something you know very little about, but precisely the kind implausible claim that you like coming up with.
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