How can we study geology and evolution without a time machine?

Creationists and others skeptical of modern science often assert that short of having a time machine, it is impossible to know with any confidence any events of the distant past. For example, creationist Ken Ham has argued that the big bang and the theory of evolution are only “theories,” because no one was around to make an eyewitness record when the the universe in general or the earth in particular was created. Thus any scientific reconstruction of those events and processes are conjectural at best and can never be “proven” [Ham2011]. Elsewhere Ham as argued that the Bible in fact provides the only reliable time machine [Ham1999]. How do scientists respond?

First of all, with respect to eyewitness records, it must be kept in mind that many other aspects of our physical world are truly beyond the realms of our senses:

  • The planets and moons of our solar system are much too far away for humans to examine first-hand, although humans may travel to Mars in 20 years or so.
  • For distant stars and their planets, we rely completely on powerful telescopes and exotic techniques such as measuring subtle changes in the light from a distant star (indicating that a planet has passed between us and the star). And galaxies are so much further away that there is, at present, no foreseeable technology to permit humans or our spacecraft to study these objects close-up and first-hand.
  • Atoms and molecules are much, much too small for any human to examine first-hand. Thus we rely on exotic equipment such as electron microscopes and atomic-force microscopes to “see” them.
  • Chemical reactions cannot yet be observed at the atomic-molecular level, at least not in any way that truly displays everything that is actually happening.
  • The nucleus of an atom is far, far smaller than anything that can be seen, even with exotic equipment such as atomic-force microscopes.

In other words, each of the above aspects of our physical world can only be studied via empirical evidence that is certainly very far from anything that we can directly sense. Yet few, if any, persons nowadays seriously doubt that the sun and the planets of our solar system really do exist at roughly the distances scientists claim them to be, or that stars and galaxies populate the universe thousands or millions of light-years away, or that there really are structures known as molecules, atoms and nuclear particles, with roughly the sizes and possessing the properties that scientists assert for them.

In addition, there are a number of ways that scientists can peer into the past with considerable confidence. To begin with, radiometric dating permits scientists to measures dates of fossil layers and the like, based on measurements of the prevalence of certain radioactive isotopes that can be found in many rocks. This technique has been refined and polished over several decades, and in the process has become very reliable. What’s more, measurements of rates of radioactivity are now on very solid ground.

There is one additional type of scientific time machine that enables us to directly study the distant past, and which also permits scientists to gain considerable confidence in the multi-million-year ages asserted by geologists for the fossil layers: viewing distant stars and galaxies is, in a very literal sense, a “time machine.” For example, when we view the Pinwheel Galaxy, which is 21 million light-years away, the image we see is a record of events that occurred 21 million years ago. Quasar 3C253 is 2.5 billion light-years away, so that the light we see today was generated 2.5 billion years ago.

In August 2011, scientists discovered a Type 1A supernova in the Pinwheel Galaxy — one of the closest every observed, and, as it turns out, definitely the most carefully studied. It was first discovered by Lawrence Berkeley Laboratory scientist Peter Nugent (a colleague of the present author), using the Palomar Transient Factory (PTF), a remotely-controlled telescope facility near San Diego, California. Because this supernova was discovered only 11 hours after it exploded (from the earth’s time frame), scientists were able to study its behavior in unprecedented detail, and several major findings resulted [Preuss2011]:

  1. The light intensity spectrum, from the earliest moments of discovery to the present (it is still being observed as of this writing), has been more accurately measured than with any previous supernova observation.
  2. The early light intensity and spectrum measurements enabled the scientists to rule out several alternative models of supernovas, including red giant stars to double-white-dwarf systems, and confirm the progenitor star was definitely a carbon-oxygen white dwarf, and its companion was a main sequence star.
  3. Initial measurements of oxygen ejected from the star found some traveling much faster than expected, but subsequent analysis explained this by determining that the oxygen was not evenly distributed when the dwarf exploded.
  4. A tremendous amount of mixing had occurred, with some radioactive nickel mixed all the way to the photosphere (the outer region that generates the light that we observe).
  5. In general, the sequence of radioactive decay, which produces most of the light we observe, was confirmed: nickel-56 decays to cobalt-56 and finally to iron-56, all in accordance with long-standing theoretical models and past empirical observations.

So the most carefully studied Type 1A supernova in history confirmed that the fundamental physical laws in play when this supernova exploded 21 million years ago are indistinguishable from those laws we measure in earth-bound laboratories today. Among these laws are the laws of radioactive decay, as well as fundamentals of quantum mechanics and general relativity. For these and other reasons, scientists have very good reasons to be entirely confident in the established old-earth picture of geology and evolution.

In summary, the large telescopes that scientists use to observe these distant galaxies are, in a very literal sense, “time machines.” And the fact that scientists can make ever-more-sensitive and comprehensive measurements of very distant astronomical objects, and in the process confirm, to exquisite precision, many the most sophisticated predictions of basic universal laws, is moot but overwhelming testimony to the reliability of these laws over cosmic time.

For additional discussion, see Radiometric dating, Reliability, Theory, Uniformitarian, Distance and Deceiver.

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