It seems strange that it is the nature of the universe to put limits on our knowledge of it. Stranger still is the idea that science in the far future might be less effective than present-day science at giving us knowledge of the world.
That is the cost of living in a universe which undergoes large-scale changes. An unpleasant consequence of this is that astronomers in the distant future will be unable to replicate the observations which give us modern cosmology.
This is fodder for very good science fiction. Imagine what it would be like to be a researcher billions of years from now, when the observable universe does not include cosmic background radiation, and when galaxies beyond the Local Group have been red-shifted into invisibility. As far as cosmologists 100 billion years from now are concerned, all that exists is an ‘island universe’ – a local population of merging galaxies populating a static, otherwise empty space.
Dennis Overbye, writing for the New York Times, gives it an appropriate headline: The Universe, Expanding Beyond All Understanding. He is chronicling the work of Lawrence M. Krauss and Robert J. Scherrer, who are about to publish their work in the The Journal of Relativity and Gravitation. (Hat tip to the Frontal Cortex for mention of the NYT article.)
The Times piece is a fun read, but don’t bother about the journal article if you don’t have a subscription. Instead, do what physicists do and check out the paper at arXiv (pronounced ‘archive’), which is like SSRN for the hard sciences. Any physicist worth their salt now self-archives using arXiv – Stephen Hawking has been doing it since 1992 – so it’s a safe guess that luminaries like Krauss and Scherrer do it too. And lo, here it is in all its open access glory…
- Lawrence M. Krauss & Robert J. Scherrer. The Return of a Static Universe and the End of Cosmology. arXiv:0704.0221v2.
Fie on thee, dinosaur publishers.
With that plug for OA out of the way, look to the following passage. It sums up the problem faced by future cosmologists:
[I]n a time comparable to the age of the longest lived stars, observers will not be able to perform any observation or experiment that infers either the existence of an expanding universe dominated by a cosmological constant, or that there was a hot Big Bang. Observers will be able to infer a finite age for their island universe, but beyond that cosmology will effectively be over. The static universe, with which cosmology at the turn of the last century began, will have returned with a vengeance.
Here is their conclusion:
[W]e live in a very special time in the evolution of the universe: the time at which we can observationally verify that we live in a very special time in the evolution of the universe!
Around the world, scholars interested in the Anthropic Principle just perked up their ears.
This is a ‘rediscovery’ of sorts. There are two other papers which cover this type of analysis, although Krauss and Scherrer provide the most comprehensive short treatment.
- T. Rothman & G.F.R. Ellis. The epoch of observational cosmology. The Observatory, vol. 107, p. 24-29 (1987).
- Abraham Loeb. Long-term future of extragalactic astronomy. Phys. Rev. D 65, 047301 (2002).
(Both of these appear in Krauss and Scherrer’s bibliography, although it may take some searching. For reasons I don’t understand, physicists and some other science-types don’t think paper titles are important. This defies my intuitions about proper citation, but perhaps it’s just indicative of a disciplinary inability to write useful titles.)
The insight to be gained from this threatens our ideas of scientific progress. Even though science is commonly – and perhaps naively – seen as getting us closer and closer to the truth, we are confronted by the knowledge that the cosmological structure of the universe determines that the future state of scientific knowledge will be worse off than it is now.
Philosophers of science: How do your accounts of scientific progress deal with this problem?
Librarians: You might start thinking about how to store cosmological data for the next 100+ billion years. Acid free paper won’t cut it, so think big. Monumental even. You might need the help of archeologists.
No matter the record, it would doubtless be received with skepticism. Think of the amount of trust future scientists would need to possess if they were to take seriously any surviving arXiv records about the Big Bang, and how empiricists of the time would heap scorn upon them. This is tremendously unsettling, but I’m fascinated by the idea that in the distant future, the Big Bang theory would become akin to Intelligent Design – a theory contradicted by the best evidence.