Bones, Rocks and Stars

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How do we know how old things are? That's a straightforward and very scientific question, and exactly the kind of thing students ought to ask; it's also the kind of question that has been muddled up by lots of bad information (blame the creationists), and can be difficult for a teacher to answer. There are a great many dating methods, and you may need to be a specialist to understand many of them…and heck, I'm a biologist, not a geologist or physicist. I've sort of vaguely understood the principles of measuring isotope ratios, but try to pin me down on all the details and I'd have to scurry off and dig through a pile of books.

I understand it better now, though. I've been reading Bones, Rocks and Stars : The Science of When Things Happened(amzn/b&n/abe/pwll) by Chris Turney.

Continue reading "Bones, Rocks and Stars" (on Pharyngula)

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How scientist know things is sort of the fundy issue, isn’t it? How do we know how old things are is one of the most important parts of many sciences, including Earth sciences, astronomy, and quite a bit of biology.

Measuring things over hundreds of years is quite different than tens of thousands and exceedingly different than measuring in the tens and hundreds of millions.

That larger concept of time is such a big part of science education that I, at least, am surprised when I discover next to no comprehension of it in a person.

I am willing to bet that there is a correlation at least between people who lack the practice of looking at things in geologic time scales and people who make negative claims about how accurate science is.

Of course,… well,… nevermind.

Well, somebody’s gotta ask this -

“Were you there?”

;)

Henry

Borrowed comment from PZ’s page:

“It’s the same thing with the idea that maybe the continents moved really fast. Think about the amount of energy that would be required to make them move that faster (in the order of miles per year) and what that would do to the surface of the earth and everything on it. Heck, we have devastating earthquakes when they move just a TINY bit faster than their usual glacial pace, which is often less than a centimeter a year at the fastest. Posted by: plunge “

Nit-picky detail: average plate rate is more like 4 cm/yr, fastest (Pacific Plate) as much as 12 cm/yr.

Yeah, I had a YEC guy in a Physical Geology class who (wierdly) accepted that the plates moved, and the radiometric dates, and everything, but said that radioactive decay must have been much much faster so it all happened in 6-10 ka. He WOULD NOT understand that if the plates had moved that fast they would have generated so much frictional heat that the entire plate would still be molten at the surface.

On the heat problem associated with accelerated decay (whether associated with a change in c or some more mysterious cause) see Joe Meert’s page “Were Adam and Eve Toast”?

RBH

Re ““Were Adam and Eve Toast”?”

Adam may have been toast, but Eve was a spare rib.

It always amazes me that so many people have no concept of prehistoric time (ie millions of years). I think a history lesson as to why we believe this would be a very useful thing to teach kids (and adults). It’s not just a philosophical notion (as AIG and co. would have us believe). A recent “Answers with Ken Ham” had the title “Millions of years-where did it come from ?” as if scientists are somehow uncertain of this. They’re not ! I think the public need to know why and how we arrived at this conclusion and why Genesis cannot be taken as proof of a young Earth.

Geologists of course suspected the Earth was very old long before Darwin. They witnessed that artifacts such as Hadrian’s wall had been around for thousands of years and yet had hardly weathered at all. Hence the Earth itself must be a lot older than a few thousand years!

The public also need to know why Kelvin got it so wrong about the age of the Earth, what Einstein’s greatest blunder was, and why Hubble was so right about his observations !

There’s also a very good article in the talk origins archive on determining distances to astronomical objects. This in itself should convince people that the Universe is not a few thousand years old. If someone then starts to go on about the speed of light then I’d mention supernova SN 1987A !

I always find it amazing that YECers like AIG constantly deny the evidence. For decades Ken Ham said: “continental drift was only a theory with no supporting evidence” and then all of a sudden he changes his mind and comes up with the ridiculous theory of “Runaway Subduction”, which Geogee has described above.This is not even a theory in my opinion, but a fanciful notion that fits in with creationist nonsense. Witness the rejection of both the Kuiper belt and Oort cloud in their “not enough short period comets claim:

http://www.answersingenesis.org/doc[…]506comet.asp

and:

http://www.answersingenesis.org/doc[…]511comet.asp

Several hundred Kuiper belt objects have now been discovered, and the detection of Sedna could possibly be the first Oort cloud body. It will be interesting to see when they drop this tired old argument as well !

Re “why Kelvin got it so wrong about the age of the Earth”

iirc, he didn’t know about radioactivity because it hadn’t yet been discovered.

Re “what Einstein’s greatest blunder was,”

Wasn’t that the cosmological constant thing?

Henry

Exactly right on both Henry. Kelvin estimated an age for the Earth of between 20 and 30 million years based on his calculations using the primordial heat of the Earth. He did not of course know about radioactivity.

Einstein correctly predicted that the Universe was either expanding or contracting, but because he new nothing about red shift he saw a static Universe and inserted the cosmological constant to compensate for this. He later called it his “greatest blunder”

Incidentally, Kelvin did a lot of his work here in Belfast in Queens University. His statue stands in the grounds of BIFFE (Belfast Institute of Further Education) or the “Tech” as it was once known. The building was once part of Queens.

But I wonder how many kids know about Kelvin and Einstein and why they got it wrong ? I certainly didn’t when I was at school !

Yeah, I had a YEC guy in a Physical Geology class who (wierdly) accepted that the plates moved, and the radiometric dates, and everything, but said that radioactive decay must have been much much faster so it all happened in 6-10 ka. He WOULD NOT understand that if the plates had moved that fast they would have generated so much frictional heat that the entire plate would still be molten at the surface.

Not to mention that a radio-decay rate a million times faster than now (enough to make roughly 6,000 years look like roughly 6 billion years) would itself have sterilized the entire planet.

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This page contains a single entry by PZ Myers published on May 15, 2006 9:30 AM.

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