Because we can determine when heavy atomic materials were produced by stellar nucleosynthesis and we can tell when the materials started to form into solid bodies from the protoplanetary disk by the strata and crystalline structures which were formed. Meteorites aren’t random formations in space; they are the residue of larger objects that had enough gravity to coalesce into a solid body and create strata, and which were later fragmented by impacts or tidal forces. (We can’t do this using the Earth’s crust because for the most part the crust is less than 2 Bya in age due to plate tectonics.) By comparing the composition of meteorites with what we know of our own planet we can estimate ages of formation with good precision to the era when planetary formation (over a span of a few tens of millions of years) occurred.
These observations, using multiple methods, are quite consistent with each other to the point that we’re able to estimate the age of the Earth quite precisely. Models of planetary formation and solar system evolution based on this age and composition have been compared to observation of other star systems in various states of planetary formation as noted by scr4 notes, and are the result of integrating knowledge from numerous fields of scientific inquiry (astronomy, geology, chemistry, astrophysics and high energy physics, cosmology, et cetera) as Exapno Mapcase says.
The o.p. is playing at naivety of basic science and espousing the “But how can you know it happened if you didn’t see it with your own eyes?” (Never mind that eyewitness testimony if frequently if not categorically unreliable.) Next, he’ll start spinning out the, “How could such a complicated system have come about by random chance?” or somesuch, and thus follows the “god of the gaps” arguments. Go ahead; try recommending a reading list of scientific knowledge or explaining how such knowledge is verified and refined by repetitive hypothesis and falsification. Just be prepared for the Forest Gump-like inquiries while he waits to find the “Gotcha!” moment that proves all scientific learning is wrong and only the Word of God tells the Real Truth, et cetera, ad nauseam.
Ah, now it’s obvious - since the source and products of the decay are bound in a rock, then the U/Pb ratio will indicate the age of the rock (well, waving away baseline issues etc.)
One last thing - weren’t these rocks melted for a significant time before solidification ? or periodically ? Sorry if I’m talking nonsense - I know next to nothing about geology.
Relating to the OP - the argument that what you don’t see with your own eyes is doubtful, is kind of strange for creationists and such. “God’s creation” is unwitnessed, unevidenced, and unnecessary. And as you mention, a simple eyewitness will surely say that the Sun orbits the Earth.
Or (as appears in the Talmud), the Earth is covered with a opaque hemisphere with 2 holes in it and the Sun and the moon traverse those holes and move in the opposite direction while dark. Stars are inside. The thickness of the cover which influences the traversal time is very important for establishing the start and end of the Sabbat - and there are many quarrels about it.
Most rocks found on the Earth’s crust are significantly younger than the Earth itself, yes, because of plate tectonics. There are areas called cratons containing Pre-Cambrian metamorphic and crystalline igneous rocks from relatively early in Earth’s history, dating back over three billion years. However, the oldest rocks we find aren’t from Earth; they’re the meteorites I mentioned previously and rocks collected from the surface of the Moon by the Apollo lunar missions. These rocks, which have not been exposed to terrestrial volcanism and tectonic effects, are composed essentially as they were at the time of formation except for radioactive decay of heavy elements (primarily isotopes of uranium and its daughter products) that occur at a statistically determinate rate. In this way, we can estimate the formation of various bodies in the Solar system including the Earth and Moon.
Here is a summary from talk.origins regarding the estimation of the age of the Earth: Three basic approaches are used to determine the age of the Earth. The first is to search for and date the oldest rocks exposed on the surface of the Earth. These oldest rocks are metamorphic rocks with earlier but now erased histories, so the ages obtained in this way are minimum ages for the Earth. Because the Earth formed as part of the Solar System, a second approach is to date extraterrestrial objects, i.e., meteorites and samples from the Moon. Many of these samples have not had so intense nor so complex histories as the oldest Earth rocks, and they commonly record events nearer or equal to the time of formation of the planets. The third approach, and the one that scientists think gives the most accurate age for the Earth, the other planets, and the Solar System, is to determine model lead ages for the Earth, the Moon, and meteorites. This method is thought to represent the time when lead isotopes were last homogeneously distributed throughout the Solar System and, thus, the time that the planetary bodies were segregated into discrete chemical systems. The results from these methods indicate that the Earth, meteorites, the Moon, and, by inference, the entire Solar System are 4.5 to 4.6 billion years old.
No, it’s the proper question because that’s exactly what happened. The answer comes from the accumulation of multiple lines of inquiry.
You can’t get large boulders that go all the way back. So scientists go small. The oldest known rock is a hair-sized crystal 4.4 billion years old. They date it by the ratio of oxygen isotopes. That data point is one of thousands about solar system formation and the later remnants of surviving rocks.
Science works by the slow accretion of data by millions of individual scientists in thousands of disciplines. If they’re lucky and smart, scientists accrete details into a full explanation, just like cosmic dust accreted to form the solar system.
Determining the age of the earth or the formation of the universe is no different in principle from the science you bathe in 24 hours a day. Data, experimentation, and theory combine to form the Internet you’re using and the device you use to get there and the lights in your room and the glasses on your face and the materials in the chair you’re sitting on and the shipping system that got them all there. Speculation certainly exists, as does poor data and bad experiments and failed theories. But you can never dismiss a consensus result you don’t like as “speculation.” Science is a coherent whole. (Holistic was a scientific term before the new-agers got hold of it.) You can’t pick and choose the parts you want to believe it.
Exapno, I hope you’re using an impersonal you and don’t doubt my attitude to the scientific method. It’s true that I am a mathematician (and math is not a science since it has zero informational content), but I have perfect credentials, being a 4th generation atheist - from both sides
I just piggybacked on this thread because I was curious about dating techniques.
In fact, I am a little puzzled by this issue on SDMB. Science vs. religion seems to be a US-only phenomenon. You’ll find very few educated people that are religious in Europe, and even those do not seem to fight science. Even the Catholic church is OK with the Big Bang and Evolution. It’s also not there in the Jewish or Muslim world, although that population is almost as religious as the American one.
The explicit adoption of the scientific viewpoint on the cosmological origin of the Universe and the theory of natural selection is fairly recent in the history of the Catholic church, although to be fair, the church didn’t make any explicit pronouncements on either topic, and Catholic scientists and natural philosophers have long been at the forefront of research in astronomy and biology.
In the United States, there is a small but extremely vocal minority of fundamentalist Christians who insist that a strict literalist interpretation of the Christian Bible is consistent with observation (even though there is not a single definitive edition of the Christian bible and even a cursory reading shows a multitude of incongruous and contradictory interpretations) and make extreme articulations to turn minor disagreements in interpretations or gaps in the fossil record into laughably implausible claims of evidence for Biblical literalism, e.g. that the Grand Canyon was formed by the same flood that Noah survived. This attitude is unfortunately reinforced by a willingness in some locales to accede to flaketastical beliefs by presenting natural selection–one of the most widely accepted theories in the history of science supported by an overwhelming amount of observational and experimental evidence–as “just a theory”, and teaching completely unsupported theological myths as an equivalent alternative.
I would opine that the differences between the United States and Europe are at least in part to most of Europe having endured a couple hundred years of intermittent wars over religion (or at least, ostensibly about religion), while the US was founded by a bunch of religious refugees who celebrated their new-found liberty to worship as they wanted by trying and executing supposed witches. It is scarcely surprising that the rest of the developed world views the United States as some kind of Monty Python skit escaped gone wrong and from the television screen. The current electoral candidates, including a buffoon pandering (if incompetently) to the Religious Right on one side and a Young Earther on the other certainly doesn’t help matters.
US saved Europe 3 times in the 20th century: the 2 world wars and the Soviet Empire (Stalin undoubtedly would have subjugated parts of W. Europe if given the chance). Even nowadays the US bears most of the pain generated by the swaying of the Arab/Muslim world moving into the 20th century.
It’s hated by many because it is there. The biggest player is always hated.
It’s true that in the past 20-30 years, US is itself searching its way and as in a mid-life crisis, experiments with mind altering drugs. Trump is almost funny. True that Cruz seems the devil, or at least a younger copy of our long-serving Fascist slime who is Netaniahu.
Anyway, US is big enough, diverse enough and smart enough that it’ll be out of the trip sometime soon. Have fun while it lasts.
Yes, I absolutely was using an impersonal you when I addressed your question.
But my comment on speculation was aimed at Henga, since she’s the one who made it. Although others have made that comment in the past, which therefore makes it a general attitude that needs correcting.
The history of Biblical literalism in the U.S. goes back to the early 19th century and its strength has waxed and waned several times since. It’s like a comfort food when times get bad and the Others make progress. Groups take comfort in their absolute rightness and the support of the community around them and become more adamant as the outside pressure grows. Eventually there is a generational divide from the causation and the wave ebbs, which I believe it’s doing now. It’s difficult for outsiders to understand and far more difficult to explain.
It is actually a good exemplar of the whole set of science/conspiracy/religion, wrapped up in something that isn’t too hard to understand the history and reality of.
Hmm, that is a pretty evil perversion of the language if that it what it is supposed to mean. I guess this is an example of how the creationists pervert the argument, and in this case invent phrases that carry a loaded meaning.
To me teaching the controversy would mean actually taking a historical thread through understanding of the Earth, and mix in with that the discovery, and rediscovery of its geometry, how it was done, and then work through the mathematics of a good set of the fallacies, and discuss the precise nature of the fallacy, and build an understanding of fallacies in argument. Good stuff for meeting and understanding the nature of other stupid anti-science arguments.
I doubt if anyone outside the U.S. can have a real grasp of how odd the confrontation of religious extremism and secular science has become here. There’s not much I say about it in GQ, except that the number of religious wins in schools is smaller every year. Not yet zero, though.
“Teach the controversy” has a very specific (and yes, very loaded) meaning in the U.S. It was appropriated by the Discovery Institute in a campaign to push for the inclusion of creationism and intelligent design in school science classes. It is completely unrelated to the scientific method or the rational discussion of science you describe.
