Science is often seen as the modern way to obtain truths. We know the earth orbits the sun, it is true. Those who work closely in the field know the process of actually doing science, both theoretical and experimental, can be painstakingly tedious, but if we’re careful we’ll always reach the truth, right? The answer is more complicated than yes or no. While science and the scientific method have proven to be incredibly powerful tools in understanding the natural world, we must be cautious with what we take science to be telling us, and more importantly be aware of what science cannot tell us. This will be the first part in a series of posts about the goals, and limits, of Science.

The problem I’d like to focus on in this post is a problem especially apparent in astronomy and evolutionary biology. The thing these fields have in common is that they’re almost entirely observational, there is little to no way to experimentally verify the theory as we would like to, since controlling for all variables is impossible. While the overarching theory of evolution may not be verifiable and falsifiable in a laboratory in the same way theories of chemistry and subatomic physics are, it can still be probed for inaccuracies and verification piecewise. Observational astronomy and Evolutionary Biology have similar time related problems, that of things happening on very large time scales. Unfortunately though, astronomy does not have quite as good a solution as evolution does (the fossil record). We can look at many different ages of the Universe at once, because it takes light time to reach us. Light from stars in a galaxy that take 1000 years to reach us, give us a snapshot of the galaxy as it was 1000 years ago.

Using only the knowledge that light has a finite speed, we now have a ‘fossil record’ of the Universe that we can use to see if the Universe has evolved as we think it did (Just as we use the fossil record to verify the predictions of the theory of evolution). The difference however, is that we can do no probing the Universe hasn’t already done for us. We can’t create a star in the lab and make it go supernovae. Not even if we had the time to do so. We would all die. Instead we have to hope our telescopes are looking in the right spot when one does go supernovae. Similarly, we cannot watch nuclear fusion happen in the core of a star. We have to infer it, as no other process we know of makes any sense to power a star. Astronomers are very clever and they are well aware of these and many similar issues, and so will often show that the theory they have is the only one which could possibly fit the data, or they will use many independent sources to enforce greater confidence in their results. As such many of these issues aren’t of great concern in the larger community.

One thought experiment exemplifies why observational science, even more so than experimental science, needs to be taken with a grain of salt when we try to say what the results are actually telling us. First, we need a little background (if you already understand cosmological redshift you can skip this paragraph): In 1929 Edwin Hubble published his research indicating that the Universe was expanding, not shrinking or static. Moreover in 1998, Saul Perlmutter, Brian Schmidt and Adam Reiss (Independently) discovered that not only was the Universe expanding, but that the expansion rate of the Universe was increasing. This accelerated expansion of the Universe dumbfounds physicists and astronomers to this day, but that is not what we’re here to discuss. Along with an accelerated expansion comes a phenomenon known as ‘redshift’. This is an effect where an object that is travelling away from an observer (you) at highspeed will appear to be redder in color than if it were not moving. A blue star in a galaxy travelling away from the milky way will appear red to our telescopes (the opposite is also true, a red giant approaching us will appear bluer than it ‘actually’ is). What astronomers currently see is that most of all the galaxies we observe are flying away from us. This means nearly all the stuff in the Universe is redshifted.

This doesn’t really seem like an issue until one realizes objects will eventually (in fact already do) appear to give off light that is infrared, which is no longer visible. “No problem, just use an infrared camera!” you might say. However, the problem persists, as over time the redshift will become greater and greater as the light shifts from infrared to microwave to radio to … well nothing. At some point the light will be so redshifted it is undetectable. As well, eventually the Universe will expand so greatly that the light will never have time to reach us. The distance between our galaxy and nearly all others will be increasing faster than the distance the light can travel. From this we draw two conclusions:

Our Universe is experiencing an accelerating expansion, which causes distant galaxies to appear redshifted.

In the distant future, none of the galaxies that we observe accelerating away from us today, will be observable.

Therein lies the problem. Consider somehow that modern human knowledge and data persists several billion years into the future and either very distant human descendants or aliens have this knowledge and data. One can imagine a conversation about the data as follows (Suppose the aliens names are Lucas and Brandon):

Brandon: “I’ve been looking through some of these documents, there’s all sorts of data and research about these ‘Distant galaxies’ this ancient civilization of ‘Humans’ talked about.”

Lucas: “I don’t see why you read that stuff, we’re far more advanced than they were.”

Brandon: “But what if they were right? Do you think there could be something out there? I don’t see why there would be so much work on something otherwise.”

Lucas: “I don’t see how there could be, in the past we’ve seriously considered their research. They were wrong! There aren’t any ‘distant galaxies’. We’ve looked and there is nothing like they describe. It’s no surprise really, ancient civilizations like theirs tended to believe in crazy things all the time.”

Brandon: “I guess you’re right. All the evidence points to that.”

Future civilizations will have no scientific reason to believe in distant galaxies. The entire Universe to them will be a small group of galaxies which are gravitationally bound to us. The most rigorous scientists of the time will be entirely justified in their view. And they will be wrong. This is not only an issue about science but also of history. How does one guarantee the credibility of data and sources over long times? I don’t propose to have any solutions to these questions, rather this post is to serve as a reminder that scientists ought to be vigilant in any and all ontological claims derived from science alone. By itself, science is not a method of metaphysical inquiry. Science at its best is a way of cataloging observations of our experience of nature and recognizing patterns in those observations.