Beyond UFOs
So how old is the Earth? The rocks we find on Earth’s surface have a great variety of ages, since different rocks solidified at different times from molten lava. The very oldest Earth rocks are about 4 billion years old, but Earth itself must be older than this, because the entire surface has been re-shaped through time. Mineral grains found within some Earth rocks date back as far as 4.4 billion years, about the same age as the Moon rocks, which must also be younger than Earth if, as currently thought, the Moon formed when a Mars- size object blasted part of Earth’s outer layers into or-bit (a hypothesis we’ll discuss in chapter 5). The very best estimates of Earth’s age come from radiometric dating of meteorites. The oldest meteor-ites are chunks of rock that must have solidified very early in the solar system’s history, at the time when Earth and the other planets were just beginning to form. These meteorites are about 4.55 billion years old, which means that our planet began to form at about that time.
If you read a few Creationist web sites, you may find people trying to argue that radiometric dating doesn’t really work. But as you’ve just seen, the scientific principles behind it are quite simple and the basic physics is very well understood: From our theory of nuclear structure we can determine which nuclei will decay and which will remain stable, and measured decay rates are in good accord with theoretical predictions. The technique of radiometric dating gains further support from the fact that, in many cases, rocks contain more than one type of radioactive isotope. If radiometric dating weren’t valid, you might expect that different isotopes would give different ages for the same rock. But they don’t: Within margins of measurement uncertainty, we invariably find that dating the same piece of rock with several different isotopes gives the same age, adding to our confidence in the validity of the technique. Moreover, we can often check the results we obtain from radiometric dating against other methods of measuring ages, giving us even more confidence that the technique works. For example, with many fairly recent archaeological artifacts, we can confirm the ages obtained from radiometric dating by measuring ages from tree ring data or even from dates written on the artifacts. In addition, astronomers have discovered completely in dependent methods for estimating the ages of stars, including the Sun. Although none of these methods give an age as precise as the age we obtain from radiometric dating, they all confirm that the Sun’s age is in the range of 4 to 5 billion years. Overall, the technique of radiometric dating has been checked in so many ways and relies on such basic scientific principles that there is no longer any serious scientific debate about its validity.
You interested in the detailed explanation of scientific principles, you have to get the book.
http://www.jeffreybennett.com/
You know guys estimate is different from actual. Astronomers estimate the composition of the planets and faraway galaxies because of its color as based on Earth minerals. The assumption is that the minerals are also same as Earth. So what if there are minerals not of this Earth? That's a possibility. Like Astronomers looks at Pluto now. Its only an estimate that it is only 100 million years old. Until we get samples from it then we know whats its age and composition. What we have though is that we have tested samples on Earth and meteors.
So how old is the Earth? The rocks we find on Earth’s surface have a great variety of ages, since different rocks solidified at different times from molten lava. The very oldest Earth rocks are about 4 billion years old, but Earth itself must be older than this, because the entire surface has been re-shaped through time. Mineral grains found within some Earth rocks date back as far as 4.4 billion years, about the same age as the Moon rocks, which must also be younger than Earth if, as currently thought, the Moon formed when a Mars- size object blasted part of Earth’s outer layers into or-bit (a hypothesis we’ll discuss in chapter 5). The very best estimates of Earth’s age come from radiometric dating of meteorites. The oldest meteor-ites are chunks of rock that must have solidified very early in the solar system’s history, at the time when Earth and the other planets were just beginning to form. These meteorites are about 4.55 billion years old, which means that our planet began to form at about that time.
If you read a few Creationist web sites, you may find people trying to argue that radiometric dating doesn’t really work. But as you’ve just seen, the scientific principles behind it are quite simple and the basic physics is very well understood: From our theory of nuclear structure we can determine which nuclei will decay and which will remain stable, and measured decay rates are in good accord with theoretical predictions. The technique of radiometric dating gains further support from the fact that, in many cases, rocks contain more than one type of radioactive isotope. If radiometric dating weren’t valid, you might expect that different isotopes would give different ages for the same rock. But they don’t: Within margins of measurement uncertainty, we invariably find that dating the same piece of rock with several different isotopes gives the same age, adding to our confidence in the validity of the technique. Moreover, we can often check the results we obtain from radiometric dating against other methods of measuring ages, giving us even more confidence that the technique works. For example, with many fairly recent archaeological artifacts, we can confirm the ages obtained from radiometric dating by measuring ages from tree ring data or even from dates written on the artifacts. In addition, astronomers have discovered completely in dependent methods for estimating the ages of stars, including the Sun. Although none of these methods give an age as precise as the age we obtain from radiometric dating, they all confirm that the Sun’s age is in the range of 4 to 5 billion years. Overall, the technique of radiometric dating has been checked in so many ways and relies on such basic scientific principles that there is no longer any serious scientific debate about its validity.
You interested in the detailed explanation of scientific principles, you have to get the book.
http://www.jeffreybennett.com/
You know guys estimate is different from actual. Astronomers estimate the composition of the planets and faraway galaxies because of its color as based on Earth minerals. The assumption is that the minerals are also same as Earth. So what if there are minerals not of this Earth? That's a possibility. Like Astronomers looks at Pluto now. Its only an estimate that it is only 100 million years old. Until we get samples from it then we know whats its age and composition. What we have though is that we have tested samples on Earth and meteors.
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