Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Richard Maddox on 08/03/2009 12:30:02
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Richard Maddox asked the Naked Scientists:
Dear Chris
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I am sure that someone is already searching for this but I have been unable to find anything on the internet.
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If there was a massive meteorite strike that wiped out the dinosaurs then I was thinking that if the earth acts as a giant gyroscope then a careful study of the Earth's rotation should show an anomaly which is getting smaller as the earth gradually corrects itself.
However, I accept that this effect as it is 65 million years ago is going to be very difficult to trace but nowadays all things seem possible?
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Are you aware of any studies of this or is it just complete rubbish as an idea.
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Regards
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Richard Maddox.
What do you think?
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The angular momentum of the meteor is going to be small compared to the earth's angular momentum. Order of magnitude comparison: The relevant quantity is mvr for the meteor, and ~(2/5)mvr for the earth. r will be the contact point, the earth's radius, so that's the same for both.
The earth's mass is 6 x 10^24 kg, with a surface rotation speed of order of .5 m/s, or ~10^24 kg-m/s of momentum
Even if the meteor's mass is 10^10 kg and moving at 100 km/s (10^5 m/s), that's 9 orders of magnitude smaller.
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To put that in plain English - yes, but only but a tiny amount that no-one would ever notice. [:D]
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No meteorite wiped out the dinosaurs! Global warming brought about by dinosaurs overexploiting their environment, much the same as we are today may have changed the sex of their eggs providing they were temperature dependant the same as alligators and crocodiles are today.
As far as a meteorite changing the rotation of the earth the trajectory could have gone either way, but in all probability would have entered aligned to the rotation so as to move it faster. But as Doc Beaver says it would not have made a significant difference either way.
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Andrew - there is quite a lot of evidence for it having been a meteorite that caused the extinction. Admittedly, it's not absolutely conclusive, but it is there. There's the iridium near the KT line, various indications of impact debris and tidal waves around the Gulf of Mexico, and other evidence much further afield all of which happened around the time of the extinction.
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Then why did it spare some dinosaurs and not others? Why didn't the impact kill the alligator and crocodile, the tortoise and turtle, Why did other species survive the impact and armageddon unleashed across the planet blotting out the sun?
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Then why did it spare some dinosaurs and not others? Why didn't the impact kill the alligator and crocodile, the tortoise and turtle, Why did other species survive the impact and armageddon unleashed across the planet blotting out the sun?
The same questions would apply to global warming; and the same answers would apply to extinction by asteroid impact. You seem to have a dog in the hunt for global warming [:)]
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Then why did it spare some dinosaurs and not others? Why didn't the impact kill the alligator and crocodile, the tortoise and turtle, Why did other species survive the impact and armageddon unleashed across the planet blotting out the sun?
As I said, the evidence is not absolutely conclusive. There are good arguments against it too.
Alligators, crocs and turtles may have been spared because they are semi-aquatic. I don't know, maybe that had something to do with it. Temperatures in the water don't vary as much as on land. There would still have been a decent food supply in the water, especially in the seas, which was not the case on land.
As for tortoises, super-long hibernation? [:D]
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Wasn't it the big collision that made the moon tilt the earth ?
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No,Neil, that was different collision. I doubt even planet-calming measures would have prevented that accident.
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Please read this through :)
"Several researchers have stated that the extinction of dinosaurs was gradual, so that there were Paleocene dinosaurs. These arguments are based on the discovery of dinosaur remains in the Hell Creek Formation up to 1.3 metres (4 ft 3 in) above and 40,000 years later than the K–T boundary.[3] Pollen samples recovered near a fossilized hadrosaur femur recovered in the Ojo Alamo Sandstone at the San Juan River indicate that the animal lived during the Tertiary, approximately 64.5 Ma (about 1 million years after the K–T event). If their existence past the K-T boundary can be confirmed, these hadrosaurids would be considered a Dead Clade Walking.[4]
Current research indicates that these fossils were eroded from their original locations and then re-buried in much later sediments (reworked).[5] "
http://en.wikipedia.org/wiki/Cretaceous%E2%80%93Tertiary_extinction_event#Duration
And then, take a look at the five major extinction events defined by Jack Sepkoski and David M. Raup in their 1982 paper.
Study the first one meticulously, because you're in it :)
http://en.wikipedia.org/wiki/Extinction_event#Major_extinction_events
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-----Some--facts-------various--quotes------
The Holocene began 11,500 years ago and is still continuing. Over 50 species are going extinct every single day. The normal "background” rate of extinction is about one species every four years. The current rate is between 30,000 and 100,000 per year. While scientists are not sure how many species inhabit the planet today, their estimates top 10,000,000. Each year, though, thousands of species, ranging from the smallest microorganisms to larger mammals, are lost forever. Some disappear even before we know of their existence.
It is the sole mass extinction that humans will witness firsthand--and not just as innocent bystanders. The Holocene extinction event is a term used to refer to the ongoing extinction of numerous animal species due to human activities. By the end of this century, over five million species (half of the species on Earth now) will likely be gone. “It’s not just species on islands or in rain forests or just birds or big charismatic mammals,” says Stuart Pimm, a conservation biologist researcher from the University of Tennessee. He notes fish, birds, insects, plants, and mammals. “It’s everything and it’s everywhere…it is a worldwide epidemic of extinctions.”"
The Holocene extinction has eliminated between 20,000 and several hundred thousand species over the course of the last 12,000 (?) years.
-----End---various quotes-----------------
Well, the number seems to vary a little here :)
On the other hand, we don't really know how many species we have, or how many that dies.
What we seem to agree on though is that it's happening..
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I wonder how many new species evolve such that one species becomes two or more each year.
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Yep, the numbers don't seem to add up here :)
On the other hand I just 'whipped' those quotes together. And thinking of it afterwards I decided to let them stand as they were. I sort of realised what I already knew :) that we don't have a really good check on this planet. That's probably why we can sit at various geographic locations and see a species disappear, thinking that it won't matter, there's enough to go around anyway :) And maybe there is? But I will still maintain that it's a small planet, and that we probably need what gene pool there still is.
Probably I could overwhelm us both :) with figures, but it's a little like those Wikis, they too can hold a bias at times, don't you agree? There is that theorem that states that 'best guesses' will lean toward the truth if made by enough people. That theorem btw was what they used when finding those atom bombs a US Airforce dropped outside Spain some time ago, on a 'whim' if I rightly remember, as they started to give up hope on finding that second one :) And we also use what we call a 'educated consensus' in our communities trusting in that they make sense. Now I understand that they are using that theorem for searches in a lot of places. It's a strange idea that one:) So I started to wonder, maybe I could make it a poll?
Like, how many of you at this site reading this think that it is true?
That we are the main cause of a new species extinction?
What do you think Vern?
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Should I make it a poll?
In the name of science:)
And curiosity?
Awh English ::))
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I'm sure it is good to protect the planet's species. But then I look at Nancy's mouse. It looks just like a regular house mouse, but likes to live in the southern California salt marshes. So we have to pay about a $1000 per mouse to protect the little guy's habitat. I think I would rather the little guy just moved to the city and started making out with its city cousins.
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How's the nightlife there? You need to be able to offer them some value for their move you know?
Aha, 'making out' you say:)
Btw: In what way do you need to pay for it?
Is the habitat unbalanced in some way?
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The real agenda here is that the Environmental Protection Agency is populated by anti-development people who use endangered species to advance their agenda. We tax payers eventually pay for everything; but it is all borrowed money right now. The money comes from the sale of US treasury bonds. Talking heads keep saying that one day, there will be no market for the bonds. [>:(]
As for the little mouses; they are probably not too far specialised that they couldn't mix it up with their city cousins. But the big thing with the EPA is that they don't want development to happen in the salt marshes; so the government buys the property and makes it a nature preserve.
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There's a way to do it that wouldn't cost the taxpayer anything. Set the reserves up as independent Islamist states and get Osama to fund them.
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Hey; I like that; switch from Obama funding to Osama funding [:)]