Nobody Can Measure the Age of the Universe

Measuring age depends on measuring light speed in ways that cannot in principle be confirmed.

Now wait a minute; we all know that the speed of light is constant in a vacuum, right? That’s the simplest expectation. Einstein thought it was true. It may well be true. But Geraint Lewis and Luke Barnes explain that it’s impossible to prove. Brian Koberlein at Universe Today reveals a conundrum little known outside of egghead astrophysics classes that has profound implications about the age of the universe.

Relativity is one of the best established theories in physics, Koberlein says, but

several physicists have pointed out that while relativity assumes the vacuum speed of light is a universal constant, it also shows the speed can never be measured. Specifically, relativity forbids you from measuring the time it takes light to travel from point A to point B. To measure the speed of light in one direction, you’d need a synchronized stopwatch at each end, but relative motion affects the rate of your clocks relative to the speed of light. You can’t synchronize them without knowing the speed of light, which you can’t know without measuring. What you can do is use a single stopwatch to measure the round trip time from A to B back to A, and this is what every measurement of the speed of light does.

Einstein simply measured the round trip speed and divided by half. Simple enough. But that conclusion includes an assumption that can never be proved for the reasons given above. What if the speed of light varied depending on whether it was approaching us or leaving us? Lewis and Barnes investigated this in a paper on arXiv. Koberlein summarizes what they concluded about anisotropic light (i.e., light that varies according to direction).

It turns out that if the speed of light varies with direction, so does length contraction and time dilation. The team considered the effects of anisotropic light on a simple relativistic model known as the Milne universe. It’s basically a toy universe similar in structure to the observed universe, but without all the matter and energy. They found that the anisotropy of light would cause anisotropic relativity effects in time dilation and cosmic expansion. These effects would cancel out the observable aspects of a varying light speed. In other words, even if the universe was anisotropic due to a varied speed of light, it would still appear homogeneous.

In short, there’s no way to tell whether it is anisotropic because the effects always cancel out. Say that light approached us faster than it left us. How would we perceive the universe? It would look the same as it does now, except for one thing:

If the speed of light varies with its direction of motion, then we would see the universe in a different way. When we look at distant galaxies, we are looking back in time because light takes time to reach us. If distant light reached us quickly in some direction, we would see the universe in that direction as older and more expanded. The faster light reaches us, the less “back in time” we would see.

Lewis and Barnes state the conclusion this way in the paper dated Dec 18, 2020:

The conclusion is that the presence of an anisotropic speed of light leads to anisotropic time dilation effects, and hence observers in the Milne universe would be presented with an isotropic view of the distant cosmos.

These same authors wrote a fascinating book together, A Fortunate Universe (Cambridge, 2016), in which they investigate many of the fine-tuning parameters of the universe and calculate each one’s ramifications for life. After having looked into a number of parameters, and having determined the life-permitting spaces within them (most of them extremely, extremely limited), they engage in a fascinating discussion. Barnes proposes the God hypothesis as the best explanation for the fine-tuning, and Lewis, his foil, plays the role of doubting Thomas. They reason together about all possible refutations of fine-tuning, along with comeback arguments, and leave ample room for the obvious conclusion: there must be a Creator God.

Update 4/18/22: In his very popular YouTube channel Veritasium on 22 Oct 2020, Derek Muller explored this counter-intuitive idea that the actual speed of light (c) is impossible to measure. He called up another science popularizer, Destin Sandlin, and succeeded in “breaking his brain” with its truth. Muller repeatedly said that it might well be that the speed of light is instantaneous toward us but 0.5 c away from us, and we could never know. If that were the case, we would be seeing the universe as it is right now. Scott Arledge discussed the significance of the exchange at ICR on 29 Jan 2021.

Graphic by David Coppedge

Creation astronomer Jason Lisle has used this conundrum about one-way speed of light to propose an answer to the starlight-time problem: i.e., if the universe is young, and the speed of light is constant, why do we see the light of distant galaxies that appear to be billions of light-years away? CEH thought it would be good for our readers to hear about two other physicists who confirm that the one-way speed of light is, indeed, an assumption that cannot be proved. Those two also agree that faster light toward earth would make the universe appear older than it is. There’s no escape; nobody can prove otherwise. Fascinating, Mr Spock would say.

Lisle’s model builds on this principle of relativity. His full theory is detailed and difficult to follow for non-physicists, but since the one-way speed of light is arbitrary, and can never be fixed by measurement, a physical model can use it as a free parameter. Why not? Any choice of radial speed is no more correct than any other. (Remember, too, that after the Michelson-Morley experiment seemed to disprove a luminiferous aether, Einstein’s choice of a constant speed of light was his starting assumption, not a measurement.)

If the radial speed toward us were infinite, there would be amazing consequences; the universe would be young but look old! Time dilation, furthermore, would take care of the look-back time, so more distant galaxies would look older than nearby ones. For Biblical creationists, it means that if God created the stars on Day Four (Genesis 1:14-19), the light could arrive on time. When Adam and Eve looked up to the night sky, the stars would already be shining. This makes sense theologically, too. If God’s purpose was to display His glory in the heavens from the viewpoint of an Earth observer, would he require billions of years before they appeared? Certainly the Master Architect of creation knows the physics. Answers in Genesis contains a synopsis of Lisle’s model.

If one model seems to defy one’s scientific preference for elegance or simplicity (which are not criteria of science anyway), there are other creation models that address the starlight and time problem: Danny Faulkner’s model, Russ Humphreys’  model and some others. The point is, the assumed age in secular astronomy need not be the correct one, and several options exist to harmonize Biblical chronology and modern astronomy using up-to-date relativistic physics.

Given the fine-tuning precision of the laws of physics, secular cosmologists must confess that the universe looks miraculous anyway. Since everyone is stuck with a miraculous universe (i.e., one that defies uniformitarian assumptions, is balanced to incredible precision, and must invoke causes not currently in operation), it seems more rational to appeal to an intelligent cause with the foresight and planning to make all things fit together (Colossians 1:17). The God of the Bible is such an all-wise and omnipotent Creator, and he told us what he did: he made the earth to be inhabited (Isaiah 45:18), and he put the stars in the heavens to declare his glory (Psalm 8, Psalm 19). Don’t assume this was hard for him. He just said, “Let there be light,” and there was light (Genesis 1:3, Psalm 33:9).