According to creationists, a magic supernatural god magicked a flat Earth into existence from nothing and put a dome over it to keep the water about the sky out. It then hung a sun and a moon from the dome and the sun has been orbiting Earth ever since. In its Bronze Age account of this creation, the magic god 'forgot' to say where the sun went at night, and creationists have puzzled over that problem for centuries, never reaching a conclusion.
Nowadays, 25% of Americans still believe Earth is the centre of the universe and the sun orbits it, although most of them now accept that Earth is no longer flat or has a dome over it, whilst believing the Bible, which says otherwise, is the inerrant word of the god who created everything from nothing.
Science, on the other hand, is providing evidence that the universe is some 14 billion years and the solar system, with the sun at the centre and Earth orbiting it, formed some 4.5 billion years ago.
One of the pieces of evidence is a meteorite, recovered from a sand dune in the Saharah Desert which has been dated to 4.5 billion years old, using the aluminium-26 – magnesium-26 (26Al-26Mg) decay system combined with the Uranium/Lead system.
First, a little AI information from ChatGPT3.5 about the dating methods used, their accuracy and limitations. Creationists especially might want to skip this since it refutes many of their claims about radiometric dating in general, and shows their responses to be parrot squawks, regurgitated on cue without the slightest understanding of the subject:
How are aluminium-26 and magnesium-26 used in dating meteorites?What I would like is for a creationist who will confidently declare the radiometric dating method to be wrong (often citing spurious C14 dates as though they have any relevance) to calculate how these decay rates have changed enough over time to make 8,000 years look like 4.5 billion years using these techniques, whilst explaining how this is consistent with another of their claims that the universe is so finely tuned that to change any of the fundamental parameters (such as the weak and strong nuclear forces on which decay rates depend) would make life impossible.
Aluminium-26 (Al-26) and magnesium-26 (Mg-26) are two isotopes that are commonly used in the field of cosmochemistry and nuclear astrophysics to date meteorites and determine the timing of various processes related to the formation and evolution of our solar system. Here's how they are used:In summary, aluminum-26 and magnesium-26 are important isotopes used in dating meteorites and understanding the chronology of events in the early solar system. Al-26 is used to estimate the time a meteoroid has spent in space since ejection from its parent body, while Mg-26 helps determine the age of meteorites and the timing of early solar system processes. These dating techniques provide valuable information for scientists studying the formation and evolution of our solar system.
- Cosmic Ray Exposure Dating with Aluminum-26 (Al-26): Al-26 is produced by the interaction of cosmic rays with elements like silicon and oxygen in meteorite parent bodies, such as asteroids. When a meteoroid (a small fragment of an asteroid or comet) is part of an asteroid, it is shielded from cosmic rays while it is within the parent body. However, once it is ejected into space due to a collision or other event, it begins to accumulate Al-26 through cosmic ray exposure.
- Measurement: Cosmogenic Al-26 isotope is measured in the meteorite upon its return to Earth. Scientists use techniques like accelerator mass spectrometry (AMS) to determine the concentration of Al-26 in the meteorite.
- Dating: By measuring the concentration of Al-26 and knowing the rate at which Al-26 is produced by cosmic rays, scientists can calculate how long the meteoroid has been exposed to cosmic rays since it was ejected from its parent body. This provides an estimate of the time it has spent in space since being separated from its parent body. This information helps date the timing of certain events, such as asteroid breakup or meteoroid ejection.
- Chronology of Early Solar System with Magnesium-26 (Mg-26): Mg-26 is an isotope that decays over time into a stable isotope of iron (Fe-26). This radioactive decay can be used to determine the age of meteorites and the timing of early solar system events.
- Measurement: Scientists measure the ratio of Mg-26 to its daughter product, Fe-26, in a meteorite sample. This isotope ratio is used to calculate the age of the meteorite.
- Dating: The half-life of Mg-26 is relatively short, approximately 0.82 million years. Therefore, Mg-26 dating is particularly useful for dating meteorites and early solar system materials that formed relatively close to the time of solar system formation. By analyzing the Mg-26/Fe-26 ratio, scientists can determine the age of these materials and gain insights into when various components of the solar system, like chondrules and calcium-aluminum-rich inclusions (CAIs), formed.
How are uranium-235 and uranium-238 used in radiometric dating of meteorites?
Uranium-235 (U-235) and uranium-238 (U-238) are radioactive isotopes commonly used in radiometric dating, including the dating of meteorites. Here's how they are used:In meteorite dating, both U-238 and U-235 dating methods are often employed, and the results from both systems can be cross-checked to enhance the reliability of the age determination. By measuring the radioactive decay of uranium isotopes and their daughter products in meteorite samples, scientists can establish the ages of meteorites and, by extension, gain insights into the timing of events in the early solar system, including the formation of meteoritic materials.
- Uranium-238 (U-238) Dating:
- Principle: U-238 is a radioactive isotope with a very long half-life of approximately 4.468 billion years. It decays through a series of radioactive transformations, eventually ending up as stable lead-206 (Pb-206). The process involves several intermediate isotopes, and each decay step has its own half-life. The U-238 to Pb-206 decay system is part of the uranium-lead dating method.
- Measurement: Scientists measure the ratio of the isotopes U-238 and Pb-206 in a sample of a meteorite.
- Dating: The age of the meteorite is determined by comparing the measured U-238/Pb-206 ratio to the known decay constants of each step in the decay chain. By calculating the proportions of U-238 and Pb-206, scientists can calculate how much time has passed since the minerals in the meteorite crystallized. This provides an estimate of the age of the meteorite.
- Application: U-238 dating is particularly useful for dating the oldest meteorites and the formation of the solar system itself because of its long half-life. It helps establish the age of the refractory minerals within the meteorites, which can be used to constrain the time of solar system formation.
- Uranium-235 (U-235) Dating:
- Principle: U-235 is another radioactive isotope of uranium, with a shorter half-life of about 703.8 million years. It also decays through a series of transformations, ultimately leading to stable lead-207 (Pb-207). The U-235 to Pb-207 decay system is used in uranium-lead dating alongside the U-238/Pb-206 system.
- Measurement: Similar to U-238 dating, scientists measure the ratio of the isotopes U-235 and Pb-207 in the meteorite sample.
- Dating: By comparing the measured U-235/Pb-207 ratio to the known decay constants for this decay chain, scientists can calculate the age of the meteorite. U-235 dating can be used alongside U-238 dating to cross-verify and improve the accuracy of the age determination.
What inaccuracies are there in these dating methods?
While radiometric dating methods, such as uranium-lead dating, are powerful tools for determining the ages of geological and cosmic materials, they are not without potential inaccuracies and sources of error. Here are some of the key inaccuracies and sources of error associated with these dating methods:To mitigate these inaccuracies and errors, scientists use various techniques and best practices, including careful sample preparation, rigorous laboratory protocols, cross-checking with multiple dating methods, and assessing the concordance of results from different mineral phases within a sample. Additionally, advances in analytical instrumentation and techniques have improved the precision and accuracy of radiometric dating over the years. Despite these challenges, radiometric dating remains a valuable tool for understanding the ages of geological and cosmic materials.
- Contamination: One of the most common sources of error in radiometric dating is contamination. If a sample is not carefully handled and protected from external sources of radioactive isotopes or non-radiogenic materials, it can lead to inaccurate results. Contamination can occur during sample collection, preparation, or storage.
- Assumption of Closed System: Radiometric dating methods assume that the system being studied has remained a closed system since the time of crystallization or formation. This means that no parent or daughter isotopes have been added or removed from the sample since its formation. In reality, some systems may experience partial loss or gain of isotopes over time, which can lead to inaccurate age determinations.
- Initial Isotope Ratios: Accurate dating relies on knowing the initial ratio of parent isotopes to daughter isotopes when the material formed. If this initial ratio is not known precisely, it can introduce uncertainties into the age calculation. This can be particularly challenging for samples with complex histories.
- Radiation Damage: In some cases, radiation damage can affect the crystal lattice of minerals, altering the diffusion rates of parent and daughter isotopes. This can lead to an inaccurate determination of the age of a sample.
- Sampling Bias: The choice of which part of a sample to analyze can introduce bias. If a specific mineral or portion of a sample is selected for analysis, it may not accurately represent the overall age of the entire sample.
- Analytical Uncertainties: The measurements made during radiometric dating, such as isotope ratios or decay constants, are subject to analytical uncertainties. Instrumental limitations, calibration errors, and measurement precision can all contribute to inaccuracies.
- Choice of Decay Constants: The accuracy of radiometric dating depends on knowing the decay constants (half-lives) of the isotopes involved. While these values are known with relatively high precision for many isotopes, there can still be small uncertainties associated with them.
- Mixing of Materials: Some materials, especially those from complex geological or cosmic environments, may have experienced mixing with other materials that have different isotopic compositions. This can complicate age determinations.
- Mineral Variability: In some cases, minerals within a sample may not have formed at the same time or may have experienced different thermal histories. This can result in different ages within a single sample.
- Choice of Dating Method: Different radiometric dating methods have different limitations and uncertainties. Choosing the most appropriate method for a given sample and research question is important.
Creationists claim decay rates have changed over time. Can this be refuted?
Creationist claims that decay rates of radioactive isotopes have changed over time are not supported by scientific evidence and are not consistent with the principles of nuclear physics. The idea that decay rates have varied significantly over Earth's history contradicts a large body of well-established scientific knowledge. Here are several reasons why this claim can be refuted:In summary, there is no credible scientific evidence to support the claim that decay rates of radioactive isotopes have significantly changed over time. Radiometric dating methods, which rely on the constancy of these rates, have been extensively tested and validated, providing reliable age estimates for geological and cosmic materials. While scientific ideas and theories are always subject to scrutiny and revision in the light of new evidence, claims of variable decay rates remain unsupported and at odds with our current understanding of nuclear physics and the natural world.
- Consistency of Decay Rates: Decay rates of radioactive isotopes are considered to be fundamental constants of nature. Numerous experiments and observations have shown that these rates remain remarkably constant over geological time scales and across various environmental conditions. Any significant variation in decay rates would have far-reaching and observable consequences in the behavior of nuclear processes.
- Confirmation through Multiple Decay Systems: Radiometric dating relies on the decay of multiple isotopes with different half-lives. If decay rates were variable, radiometric dating would yield inconsistent and discordant results when different isotopic systems are used on the same sample. However, radiometric dating methods are internally consistent and produce reliable age estimates when applied correctly.
- Laboratory Experiments: Scientists have conducted extensive laboratory experiments and studies to investigate the possibility of changes in decay rates under various conditions. These experiments have consistently shown that decay rates remain constant within the margins of measurement error.
- Astrophysical Observations: The fundamental constants of nature, including decay rates, are crucial for understanding the behavior of stars, galaxies, and the universe itself. Astrophysical observations and models rely on the stability of these constants to explain the behavior of celestial objects.
- No Mechanism for Changing Decay Rates: Creationist claims typically lack a scientifically plausible mechanism for changing decay rates. Nuclear decay processes are governed by the fundamental forces of nature, such as the strong and weak nuclear forces and electromagnetic interactions, and there is no known way for these forces to vary significantly over time.
- Concordance with Other Dating Methods: Radiometric dating is often cross-checked with other dating methods, such as dendrochronology (tree-ring dating), varve dating (sediment layers), and stratigraphy (geological layering). These independent dating methods consistently support the reliability of radiometric dating and the constancy of decay rates.
The discovery of the meteorite and its significance is the subject of an article in The Conversation by Evgenii Krestianinov, a PhD candidate in the Research School of Earth Sciences, Australian National University. His article is reprinted here under a Creative Commons license, reformatted for stylistic consistency:
Sahara space rock 4.5 billion years old upends assumptions about the early Solar System
Evgenii Krestianinov, Australian National University
In May 2020, some unusual rocks containing distinctive greenish crystals were found in the Erg Chech sand sea, a dune-filled region of the Sahara Desert in southern Algeria.
On close inspection, the rocks turned out to be from outer space: lumps of rubble billions of years old, left over from the dawn of the Solar System.
They were all pieces of a meteorite known as Erg Chech 002, which is the oldest volcanic rock ever found, having melted long ago in the fires of some now-vanished ancient protoplanet.
In new research published in Nature Communications, we analysed lead and uranium isotopes in Erg Chech 002 and calculated it is some 4.56556 billion years old, give or take 120,000 years. This is one of the most precise ages ever calculated for an object from space – and our results also cast doubt on some common assumptions about the early Solar System.
The secret life of aluminium
Around 4.567 billion years ago, our Solar System formed from a vast cloud of gas and dust. Among the many elements in this cloud was aluminium, which came in two forms.
First is the stable form, aluminium-27. Second is aluminium-26, a radioactive isotope mainly produced by exploding stars, which decays over time into magnesium-26.
Aluminium-26 is very useful stuff for scientists who want to understand how the Solar System formed and developed. Because it decays over time, we can use it to date events – particularly within the first four or five million years of the Solar System’s life.
The decay of aluminium-26 is also important for another reason: we think it was the main source of heat in the early Solar System. This decay influenced the melting of the small, primitive rocks that later clumped together to form the planets.
Uranium, lead and age
However, to use aluminium-26 to understand the past, we need to know whether it was spread around evenly or clumped together more densely in some places than in others.
To figure that out, we will need to calculate the absolute ages of some ancient space rocks more precisely.
Looking at aluminium-26 alone won’t let us do that, because it decays relatively quickly (after around 705,000 years, half of a sample of aluminium-26 will have decayed into magnesium-26). It’s useful for determining the relative ages of different objects, but not their absolute age in years.
But if we combine aluminium-26 data with data about uranium and lead, we can make some headway.
There are two important isotopes of uranium (uranium-235 and uranium-238), which decay into different isotopes of lead (lead-207 and lead-206, respectively).
The uranium isotopes have much longer half-lives (710 million years and 4.47 billion years, respectively), which means we can use them to directly figure out how long ago an event happened.
Meteorite groups
Erg Chech 002 is what is known as an “ungrouped achondrite”.
Achondrites are rocks formed from melted planetesimals, which is what we call solid lumps in the cloud of gas and debris that formed the Solar System. The sources of many achondrites found on Earth have been identified.
Achondrite meteorites like Erg Chech 002 offer clues about the early years of the Solar System.
Yuri Amelin, CC BY
Still other achondrites, including Erg Chech 002, are “ungrouped”: their parent bodies and family relationships are unknown.
A clumpy spread of aluminium
In our study of Erg Chech 002, we found it contains a high abundance of lead-206 and lead-207, as well as relatively large amounts of undecayed uranium-238 and uranium-235.
Measuring the ratios of all the lead and uranium isotopes was what helped us to estimate the age of the rock with such unprecedented accuracy.
We also compared our calculated age with previously published aluminium-26 data for Erg Chech 002, as well as data for various other achondrites.
The comparison with a group of achondrites called volcanic angrites was particularly interesting. We found that the parent body of Erg Chech 002 must have formed from material containing three or four times as much aluminium-26 as the source of the angrites’ parent body.
This shows aluminium-26 was indeed distributed quite unevenly throughout the cloud of dust and gas which formed the solar system.
Our results contribute to a better understanding of the Solar System’s earliest developmental stages, and the geological history of burgeoning planets. Further studies of diverse achondrite groups will undoubtedly continue to refine our understanding and enhance our ability to reconstruct the early history of our Solar System.
Evgenii Krestianinov, PhD candidate, Research School of Earth Sciences, Australian National University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
For creationists who claim to be more expert than the experts, that should be a simple task, unless their claims are mere posturing with no substance, and their assertions the equivalent of trained parrot squawks, made without any understanding of the noises they make.
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