The Age of the Earth

What is the Age of the Earth?

As determined by the most recent geological and physical measurements, the Earth is (4.54 +/- 0.05) billion (that's "billion" with a "b") years old. Here are some references that explain the independent scientific methods used to measure this age.

  • "Age of the Earth." US Geological Survey (USGS).
  • "The age of the Earth in the twentieth century: a problem (mostly) solved." G. Brent Dalrymple (College of Oceanic and Atmospheric Sciences, 104 Ocean Admin Building, Oregon State University , Corvallis, OR 97330-5503, USA). Geological Society, London, Special Publications January 1, 2001, v. 190, p. 205-221.
  • "Lead isotope study of basic-ultrabasic layered complexes: Speculations about the age of the earth and primitive mantle characteristics." Gérard Manhesa, Claude J. Allègrea, Bernard Dupréa, Bruno Hamelina. Earth and Planetary Science Letters Volume 47, Issue 3, May 1980, Pages 370–382.
  • "Age of the Earth" C. Patterson, G. Tilton and M. Inghram. Science. New Series, Vol. 121, No. 3134, Jan. 21, 1955.

Is the Age of the Earth a Scientific Issue?


The age of the Earth is a purely scientific issue. It is not a religious, legal, or philosophical issue. While questions like, "How many people should I be allowed to marry?" or "Should I kill my enemy?" cannot be addressed by science and instead need values or moral input (e.g. from the law, philosophy, religion, etc.), the age of the Earth is not such a question. It is not a moral question. It is a question of the natural world.

Some folks, like Terry Mortenson from Answers In Genesis (see below, under claimaints), believe scientists cannot address the age of the Earth because no one was there to see it. Not only is this ludicrous, it's an argument based entirely on the Argument from Ignorance fallacy. Mortenson is demanding eyewitness testimony. Not only is eyewitness testimony one of the weakest kinds of evidence, scientific methods are routinely used to reliably determine the ages of things, man-made (like paintings, which sometimes have a provenance that can be used to test the dating method) and otherwise (e.g. trees, fossils, rocks, etc.).

The age of the Earth is a scientific question because aging is a process of the natural world, and therefore should be governed by natural laws. No faith is required to determing the ages of things. There are measureables that can be used to do this.

Consider a simple tree. How old is the tree? No one may have been around when a tree was planted, but knowing how tree rings form over time, one can quite accurately date the age of a tree (to within months). Radiometric dating can be checked against that on trees to see how well they agree (hint: they agree very well). There are other ways to date things (e.g. paintings) based on different lines of evidence.

The age of the Earth is known both by the ages of rocks gathered from other bodies in the solar system (e.g. meteorites and the moon) and also by knowing how old are the oldest rocks found on Earth (the oldest date back to over 4 billion years). These different lines of evidence converge on the accepted number: 4.54 billion years.

Why Should Anyone Care?

President George W. Bush's Presidential Council of Advisors on Science and Technology (PCAST) generated a report, at the President's request, regarding the economic impact of scientific research. This report went public in 2002 and unequivocally stated that about half of the economic growth in the U.S. since World War II was attributable to "fundamental research," curiosity-driven scientific inquiry without regard to its immediate application. (Ref: "Assessing U.S. R&D Investment." PCAST Archives. The report was based on a study of Federal Research and Development funding conducted by the RAND Corporation and the American Association for the Advancement of Science.)

Asking basic questions like "How old is the Earth?", "Why is life so diverse?", and "What is the basic building block of the universe?" is the same as curiosity driven inquiry. There is no obvious immediate application of the answers to these questions except to answer these questions. However, asking and answering them has led to deep understanding of the laws of physics (thermodynamics, electromagnetism, and nuclear and particles physics) and modern medicine (understanding of the cause of drug resistant infections, of the structure of the immune system, etc.).

In order to answer the question, "How old is the Earth?", we must understand the laws of heat and heat transfer, as well as the behavior of the nucleus of the atom. The unstable nuclei of certain atoms (e.g. Uranium) decay at a well-defined rate. This is an observation. The explanation stems from quantum physics. Together, the observation (Uranium nuclei decay to other nuclei with a well-defined rate) and the explanation (quantum physics) allow precise measurements of the age of rocks or other material containing different atoms. These measurements, both of material on earth, material from meteorites that struck earth a long time ago, and even rocks from the moon, converge on a single age for the Earth - 4.54 billion years. The measurement has uncertainty - about 1% of the value of the age - due to the methods involved.

The age of the earth is a question that is part of the larger web of science. If the age of the Earth were not as determined by radiometric methods based on the laws of physics, then most of the technologies we take for granted today (mobile communications, nuclear power, etc) would be unpredictable since they are based on the same laws. The objective nature of reality, governed by discernable laws, makes possible the creation of technology based on those laws whose behavior can be designed and predicted with great accuracy. The same laws that let us do that also give us a consistent age for the Earth.

Who Says the Earth Isn't 4.54 billion years old?

Lots of people like to argue that we either don't know the age of the Earth, or that the Earth is only a few thousands of years old, or that the question of the age of the Earth is not a scientific one because no one was there to see it. Many of these arguments are based on ignorance, religious belief, or a combination of those two things. Mistaking religious belief for scientific evidence is something we cover a lot in this class. Remember, arguing that religious beliefs are not reliable evidence is NOT the same as arguing against religion. If you are going to advance a belief absent evidence as evidence for something else, you run right into science, which uses evidence collected from the natural world to understand the properties of the natural world.

Here are a few of the many people who claim the Earth is not 4.54 billion years old.

  • 2012 - Florida Senator Marco Rubio: in an interview with GQ, Rubio was asked, "How old do you think the Earth is?". Rubio responded:

    "I'm not a scientist, man. I can tell you what recorded history says, I can tell you what the Bible says, but I think that's a dispute amongst theologians and I think it has nothing to do with the gross domestic product or economic growth of the United States. I think the age of the universe has zero to do with how our economy is going to grow. I'm not a scientist. I don't think I'm qualified to answer a question like that. At the end of the day, I think there are multiple theories out there on how the universe was created and I think this is a country where people should have the opportunity to teach them all. I think parents should be able to teach their kids what their faith says, what science says. Whether the Earth was created in 7 days, or 7 actual eras, I'm not sure we'll ever be able to answer that. It's one of the great mysteries."


    At the time he said this, Rubio was one of the members of the U.S. Senate Committe on Commerce, Science, and Transportation. This committee is responsible for funding basic science agencies like the National Science Foundation, which in term funds fundamental research in biology, geology, chemistry, math, computation, and physics, among other things. His answer demonstrated sweeping ignorance of science, its role in the economy, and all of the other important issues discussed above.

    A few weeks after his long and rambling answer to the GQ interviewer, Rubio appeared to have slightly back-tracked during an interview with Politico:

    "There is no scientific debate on the age of the Earth. I mean, it's established pretty definitively. It's at least 4.5 billion years old . . . I just think in America we should have the freedom to teach our children whatever it is we believe. And that means teaching them science. They have to know the science, but also parents have the right to teach them the theology and to reconcile those two things."


    This is a scientifically accurate answer, and his subsequent moral/policy point respects both religion and science without compromising either thing. It's unclear when he first says "teach" whether he means "in the home" or "in the science classroom." It's a bit clearer in the sentences afterward that he means "teach science in school" and "allow parents the right at home to reconcile science and religion."

  • Bryan Fischer (American Family Association) and Terry Mortenson (Answers in Genesis): on the Nov. 20, 2012 airing of Fischer's radio program, and in response to the scientific outcry over Rubio's above comments, Bryan Fischer hosted Terry Mortenson used a common creationist argument against an old Earth: basically, since no one was around to see the Earth formed, it's impossible to know it's age other than from the Bible. This is a common logical fallacy (Argument from Ignorance) applied as if it were evidence of something. If one could reliably apply the argument from ignorance, it would be impossible to convict criminals on anything other then eyewitness testimony, which is known from scientific studies to be the WEAKEST form of evidence.

    Here is what was actually said by Mortenson: " . . . the only way we can know the age of the earth is if we have eyewitness testimony of somebody who was there, and that's what we have in the Bible, which is the inspired word of the Creator."

  • U.S. Representative Paul Broun: at the time he said the following, Broun was serving on the U.S. House of Representatives Science and Technology Committee.

    "All that stuff I was taught about evolution and embryology and the big bang theory, all that is lies straight from the pit of Hell. And it's lies to try to keep me and all the folks who were taught that from understanding that they need a savior. You see, there are a lot of scientific data that I've found out as a scientist that actually show that this is really a young Earth. I don't believe that the earth's but about 9,000 years old. I believe it was created in six days as we know them. That's what the Bible says."


  • Internet Websites: since anybody can say whatever they want on the internet, independent of formal peer review of even basic knowledge of the scientific method, the internet is a great place to find claimants on this subject. For instance, check out:
    • Dr. Don Patton: Incidentally, the "Dr." in "Dr. Don Patton" is believed to be a false credential. He has claimed to receive a Ph.D. in Geology from Queensland Christian University (QCU). QCU is an unaccredited university, and confirmation that he in fact received a Ph.D. from QCU has been neither obtainable from QCU nor Patton himself. Patton has on occasion been questioned about his degrees and has deflected or back-tracked from earlier claims. More can be read here:

      Incidentally, Patton is famous in the Dallas area for claiming that there are both human and dinosaur footprints together in riverbeds in Glen Rose, TX. You can visit them yourself, and you can talk to real, degreed Geologists from SMU about those formations.

    • Randy Berg: Berg is a creationist with no credentials in science at all - even according to on his website. But he is cited by creationist organizations (c.f. as someone who makes valid scientific criticisms of the age of the Earth.
  • Bishop of Armagh James Ussher (1654): Ussher was the first to try to compute the age of the Earth using the Bible. Note that his calculation was prior to the existence, in any modern sense, of the sciences of chemistry, geology, or physics (those emerged in something resembling their present scientific form in the 18th-19th centuries). You can read more on his Wikipedia page: Ussher calculated that the Earth was created on Sunday, 23 October 4004 BC. (no uncertainty was quoted). This is where young Earth Fundamentalists derive their belief in the age of the Earth, absent scientific evidence.

Who Doesn't Have a Problem with the Scientific Measurement of the Age of the Earth?

  • Scientists: while there are plenty of questions to be worked out (for instance, when different planets formed in the solar system and how scattered their formation was in time), no serious practicing scientist doubts the authenticity of the evidence for a 4.54 billion year old Earth. To do so would be to cherry-pick evidence or aspects about natural laws that you don't like.
  • The Catholic Church: In a July, 2004 statement from the International Theological Commission (headed by then Cardinal Ratzinger, now Pope Benedict XVI), the Church proclaimed:

    According to the widely accepted scientific account, the universe erupted 15 billion years ago in an explosion called the 'Big Bang' and has been expanding and cooling ever since. Later there gradually emerged the conditions necessary for the formation of atoms, still later the condensation of galaxies and stars, and about 10 billion years later the formation of planets. In our own solar system and on earth (formed about 4.5 billion years ago), the conditions have been favorable to the emergence of life. While there is little consensus among scientists about how the origin of this first microscopic life is to be explained, there is general agreement among them that the first organism dwelt on this planet about 3.5–4 billion years ago. Since it has been demonstrated that all living organisms on earth are genetically related, it is virtually certain that all living organisms have descended from this first organism. Converging evidence from many studies in the physical and biological sciences furnishes mounting support for some theory of evolution to account for the development and diversification of life on earth, while controversy continues over the pace and mechanisms of evolution.


  • Televangelist Pat Robertson:the host of "The 700 Club" recently came out in defense of the science of the age of the Earth and the universe. He was quoted as saying,

    "Look, I know that people will probably try to lynch me when I say this, but Bishop [James] Ussher wasn't inspired by the Lord when he said that it all took 6,000 years. It just didn't. You go back in time, you've got radiocarbon dating. You got all these things and you've got the carcasses of dinosaurs frozen in time out in the Dakotas. They're out there. So, there was a time when these giant reptiles were on the Earth and it was before the time of the Bible. So, don't try and cover it up and make like everything was 6,000 years. That's not the Bible . . . If you fight science, you're going to lose your children, and I believe in telling it the way it was."



How the Earth was Made: a documentary based on the scientific evidence regarding the age and formation of the Earth.