As a critique of many of the historical sciences, Young Earth Creationists have had to offer alternative ideas about cosmology to allow for a universe that is only thousands of years old. The standard explanation is that the universe originated in a Big Bang, is many billions of years old, giving light time to travel across the universe. One of supporting observations of this is that many astronomical objects are visible, although they are many millions and even billions of light years distant. According to the laws of physics, the light that we are observing therefore began its journey millions or billions of years ago. Creationists who reject the stated age of the universe must therefore posit alternative explanations for the observations.
Old Earth creationists do not object to the standard model of cosmology in astrophysics and are known to debate their fellow creationists over the issue.
There are only a handful of Young Earth Creationists who claim to have alternatives to the Big Bang model. The rest of the scientific community rejects outright these alternatives. There are a handful of amateurs and professionals who support non-standard cosmologies that are unrelated to creationism.
Arguments largely abandoned by creationists
Inaccurate astronomy
The current cosmological paradigm is built on painstaking observations and the rejection of scientific theories (for example steady-state theory) which do not fit the observed data. Distances to cosmological objects are obtained through a variety of techniques that serve as links in the distance ladder of cosmology. For example, distances to supernovae can be obtained by means of standard candle techniques. Early responses by Young Earth Creationists tended to challenge these astronomical measurements and assert that distant objects were not as far away as thought. For example, creationists would challenge the assumption that redshift and distance were necessarily correlated. The increased number, precision, and accuracy of independent authentications of distances has caused this approach to fall into disfavour. However, many creationists continue to question science results they believe run counter to their worldview.
Light created in transit
Some creationists have held that light that only appears to have come from distant objects, but is really created in transit. This is a variation of the so-called Omphalos hypothesis of a creator who misleads the world by creating the appearance of age or, in this case, light-travel time. As the idea relies on a supernatural conspiracy to create the appearance of a material reality that is different from actual reality, it is an epistemologically impossible to refute idea similar to solipsism. The assumptions science generally relies on are that unfalsifiable claims like that are not considered worthy of scientific consideration.
One bizarre implication of this creationist idea would be that supernovae that occur in the distant universe and are visible to us only after the transit time for light would have had to have been manufactured optical effects at the time of creation. In other words, in this idea distant supernovae never really happened even though we see them.
Arguments still employed by creationists
Russell Humphreys' arguments
In a bounded universe, creationists claim that unspecified relativistic effects might cause time to pass more slowly near the center than at its periphery. If the Earth was near the center (see Modern geocentricity), then far-away objects might indeed be millions of years old, while the earth would be only thousands of years old, even if created at the same time. The author of this idea is Russell Humphreys (Link). In recent years, he has argued that he could create such an effect by having the universe arising from a white hole rather than from a Big Bang. (Link to PDF).
This cosmology has been criticised on several grounds:
- A bounded universe would also have observable topological effects which are not observed. The observations currently point to a universe that is topologically constrained to be unbounded on observable scales.
- The effect of Gravitational time dilation should be observable if Humphreys is correct. On the contrary, we observe (from the periods of Cepheid variable stars, from orbital rates of binary stars, from supernova extinction rates, from light frequencies, etc.) that such time dilation does not exist. There is some time dilation corresponding with Hubble's Law (further objects have greater redshifts), but this is due to the well-understood expansion of the universe, and it is not nearly extreme enough to fit more than 10 billion years into less than 10,000.
- Humphreys tries to use clocks in the earth's frame of reference. But the cosmos is much older than the earth. Judging from the heavy elements in the Sun and rest of the solar system, our sun is a second generation star at least. Billions of years must have passed for the first stars to have formed, shone, and novaed, for the gasses from those novas to have gathered into new star systems, and for the earth to form and cool in one such system. The billions of years before the earth are not accounted for in Humphreys' work.
- Humphreys' idea assumes that the earth is in a huge gravity well. The evidence contradicts this assumption. If the earth were in such a gravity well, light from distant galaxies should be blueshifted. Instead, it is redshifted.
- The idea also assumes the existence of an edge to the universe. Observations of the topology of the universe see evidence for no physical edge. In order for Humphreys to be correct, the observed expansion of the universe would have to be explained as being due to an effect that was not found in Friedmann cosmology . The unexplored cosmological implications, the lack of explanations for cosmological observations, and the lack of supporting observations relegate Humphrey's explanation to little better than a falsified hypothesis.
- Humphreys' cosmology is impossible if one sticks to the laws of physics as we know them. This weakness Humphreys readily acknowledges, although to him it is a strength. Humphreys refers to Isaiah 40:22, Who stretches out the heavens like a curtain, and spreads them out like a tent to Dwell in. To Humphreys, this is an indication that God side-stepped the laws of physics, to drag spacetime out of its own black hole and force the universe to expand, in what Humphreys calls a "white hole cosmology". The need for divine intervention comes about because Humphrey's assumes a bounded universe with a distinct center, both of which are aspects absent from standard cosmology.
- These ideas attempt to fit the same cosmological data that the Big Bang theory explains, but fail to do so in the existence of detailed measurements of the cosmic microwave background, the observed abundance of light elements, and the large scale structure observations of the means by which galaxies and clusters of galaxies are organized. Modifications to the idea try to sidestep the issue by attempting to offer only an alternative to the question of how light from distant stars millions of light years away could be visible from Earth if the universe is only 6,000 years old. They rely on observations associated with the distance to faraway objects only, and offer no scientific test of the ideas. The papers written on the subject are, at best, handwaving arguments from a non-rigorous perspective: hardly an alternative to scientific cosmology.
- See Conner and Page [1998] and Conner and Ross [1999] for several other technical objections. It should be noted that Humphreys claims to have answered these and other objections. Mainstream proponents maintain he hasn't answered the most basic points.
Barry Setterfield's arguments
Another approach was to consider that the speed of light may not have been constant. If the speed of light were significantly faster in the past, light from distant objects could have reached earth in much less time. Such an approach is attractive — after all, it seems impossible to prove today that fundamental physical constants have not changed over time. This hypothesis, called the "C decay" hypothesis, was originally proposed by Barry Setterfield .
This cosmology has been criticised on several grounds:
- A change in the speed of light of the necessary magnitude would have had profound implications on other physical processes, particularly the nuclear fusion reactions that power the Sun. Given that these measurements have been extremely accurate over a long period it seems unlikely to opponents of this theory that there were substantial changes in the last few thousand years.
- Setterfield who claims to document the decreasing speed of light, used faulty techniques. Many different measurements of the speed of light have been made in the last 180 or so years. The older measurements were not as accurate as the latest ones. Setterfield chose 120 data points from 193 measurements available (see [Dolphin n.d.] for the data), and the line of best fit for these points shows the speed of light decreasing. If you use the entire data set, though, the line of best fit shows the speed increasing. However, a constant speed of light is well within the experimental error of the data. If Setterfield's formulation of the changes in physical parameters were true, then there should have been 417 days per year around AD 1, and the earth would have melted during the creation week due to the extremely rapid radioactive decay. [Morton et al. 1983]
- While a variable speed of light has been proposed seriously by non-creationist theoreticians like Paul Davies, the relative changes that are allowed from current observations are far less than the relative changes that the creationists require. Upper limits on how much the speed of light has changed with cosmological epoch can be made by observing atomic spectroscopic lines in distant objects which have ratios that are set by fundamental constants like the speed of light. The upper constraint from such observations is set at roughly one part in 107 for the variation of the speed of light back to the epoch of recombination.
- It does not explain why distant pulsars do not appear to speed up, as they would if the speed of light was indeed slowing down. More information.
Genesis as a history only of the creation of the Earth
Some YECs hold that Genesis records only the creation of the Earth and solar system, not the entire universe, and that the universe may be many billions of years old, allowing time for the light to travel. While this idea allows the avoidance of the question of cosmological distances altogether, the development of the ability to measure the size of the universe was dependent in part on the development of dating techniques of the Age of the Earth and the solar system. In particular, these ages put important lower bounds on the age of the universe before the details of the Big Bang model were known. Since the speed of light is constant, this also gave a limit to the observable size of the universe.
The measurement of the age of the solar system is very well constrained by radiometric dating methods of meteorites found on Earth. Consistently, the meteorites give the very similar 4.56 billion year ages which serve as important astronomical markers for the age of the solar system. The oldest rocks on the Earth are found to be roughly a billion years younger than that giving a rough age estimate for when the latest the crust of the Earth could have cooled.
There is a level of overlap within science between each of the different disciplines. While a cosmologist might not ever work on a planetary science mission, the historical interconnectedness of these disciplines is undeniable and there is no telling when in the future interdisciplinary collaboration will occur.
Creationist critiques of mainstream cosmology
Advocates of creationist cosmologies highlight what they consider to be problems with mainstream Big Bang cosmology, in particular the classic horizon problem, criticizing its most common standard cosmological resolution, cosmic inflation. When such critics refer to these issues in reply to light-travel problems in their own cosmology, however, they commit the fallacy of tu quoque.
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