Of Boltzmann Brains

Present day Physics – especially elementary particle physics and cosmology – has long reached the place where speculation and discussion about the origin and fundamental nature of our universe is no longer a philosophical issue, but a concrete issue related to phenomena we can observe and manipulate.

One of the most common notions is that the universe appeared accidentally – out of nothing – as in a Big Bang, which then evolved to its present state. There are a host of variations on the scenarios by which this could happen and a large body of observation from which the many theories can be tested. 

The standard paradigm of cosmology around which most theories group is called the

/\CDM model (The Greek letter /\ stands for the cosmological constant and CDM for Cold Dark Matter). The cosmological constant, /\, was originally introduced by Einstein into his equations for his General Theory of Relativity in order to control or eliminate solutions to the equations  which led to an expanding universe. A few years later evidence showed that the universe was indeed expanding and Einstein called the insertion of the constant in his equations one of his greatest blunders.

Since that time evidence has pointed not only to an expanding universe, but to an accelerated expansion. The accelerated expansion can be ascribed to a so called Dark Energy that would have to make up about 68% of energy in  the universe, but the simplest model is to ascribe the accelerated expansion to a constant that is a feature of the vacuum of spacetime. There are other theoretical models which attempt to explain the accelerated expansion, such as Scalar, Vector, Tensor theories or models which use an inhomogeneous universe….

CDM, cold dark matter, is needed to account for the rotation curves of galaxies and other effects such as lensing of galaxies and has been discussed in a couple of previous blogs. Like Dark Energy (DE), it is called Dark because it has not been observed directly – only by its large scale gravitational effect. It is called Cold because to fit into current models the DM must move

slowly – i.e. at non-relativistic energies. CDM makes up the bulk of the matter content of the galaxies in the universe in the /\CDM model (about 27% of the total energy budget), with ordinary matter – neutrons, protons, electrons, photons, etc. that we are familiar with making up about 4-5% of the observed universe.

Although there is an immense library of work on the many facets of the standard paradigm, there are also some basic logical or philosophical problems that continue to interest people in the field.

One of the earliest proponents of the idea that our universe is a statistical fluctuation of some kind was a giant in the field of statistics – Ludwig Boltzmann. Logically, if the whole universe can come into being as a  random fluctuation then so can intelligent observers in such a universe.  From a statistical point of view the occurrence of conscious beings like ourselves is extremely unlikely. The likelihood of any conscious beings coming into existence is also low, but in principle less complicated versions of conscious beings should be more likely than ourselves. Conscious brains that come into existence by random fluctuations in the physical environment of the universe have been dubbed Boltzmann Brains. According to Wikipedia, the term was coined by Andreas Albrecht and Lorenzo Sorbo in 2004.

In such a circumstance, Boltzmann Brains should be much more common in the universe than complex creatures such as ourselves. There is not only our own complexity – which we are still searching to understand – but also the whole complexity of our evolved environment and associated life forms that have preceded us and coexist with us. One might visualize some collection of gases or nebulae forming a capacity to observe and reflect on its surroundings. Or there may be much simpler organisms that could be capable of evolving in a much simpler  and shorter series of evolutionary stages than our own has been. 

Scientists who have been bemused with such thoughts have also put forward the notion that if a random fluctuation created the universe, then random fluctuations in that universe should also, over a very long time, also lead to fluctuations that permit the universe to observe or reflect on itself – Boltzmann Brains (BBs). Also if Boltzmann Brains in general are simpler than us then there should be vastly more BB observers in our universe than observers like ourselves. We are, it seems, the latest link in a presumably long and unlikely chain of events, and therefore we should have lower probability of occurring than simpler more spontaneous forms of observing intelligences.

In a recent paper in ArXiv: 1708.00449, Bayes Keeps Boltzmann Brains at Bay, Don Page argues that what he terms “conventional Bayesian reasoning” is sufficient to remove the concern that the universe might be overrun with BBs. Page is primarily responding to a recent paper by Sean Carroll, Why Boltzmann Brains are Bad, arXiv:1702.00850 [hep-th].

Evidently Carroll, according to Page, argues that Boltzmann Brains are “cognitively unstable and therefore self-undermining and unworthy of serious consideration” 

On this note of serious consideration, while reading background material on this subject, I came across a New York Times article (Dennis Overbuy, Jan. 15, 2008, Big Brain Theory: Have Cosmologists Lost Theirs?) which provides more background in layman’s language.

In any event, Page provides some reasoning from probability theory as to why there is unlikely to be a preponderance of random or chaotically appearing BB’ s compared to the occurrence of what he calls Ordinary Observers (OO’s) like ourselves.

All of these speculative discussions are ultimately based on the premise that intelligence, along with the existence of the universe itself, popped into existence in some random or chaotic fashion. Accepting this premise then leads naturally to conclusions like those of randomly occurring BB’s, as well as of course multiverses outside our own and so on.

None of these speculations about the occurrence or nature of intelligent life are based on actual observed data. That is, there is no definite evidence that life, let alone intelligent life exists beyond our own planet, although there is evidence that encourages speculation – such as the existence of organic compounds in space and on other planets, evidence of water on other planets, and so on. As well, the fact that there are many planets known to exist around other stars leads naturally to the supposition that other forms of life and intelligence should also exist. 

The notion that there ought to be or has to be other life forms, and specifically intelligent lifeforms “out there” has even been given a name – the Fermi Paradox – after a comment made by the Nobel Prize winning physicist, Enrico Fermi, many years ago – “Where is Everybody?”

There is an apparently popular book – which I have not read – by Stephen Webb, If the Universe is Teeming with Aliens… Where Is Everybody: Seventy-Five Solutions to the Fermi Paradox and the Problem of Extraterrestrial Life Science and Fiction

One of the ideas cited in this book, apparently, is the hypothesis of a writer, John M. Smart, who among other things suggests an answer to the Fermi paradox is that as beings become more intelligent they seek inward for knowledge rather than outward. Therefore more intelligent beings than ourselves would not be seeking us out or be detectible to us. Smart has a website and a blog of his own that can be accessed by googling his name.

Evidently there are at least 74 other speculations on where everybody is or why we don’t see evidence of BBs or other Alien forms.

Scientists have sought for such evidence and space probes of various kinds have been devised to seek out signs of life and of intelligence. Notwithstanding that there may be an abundance of other forms of life and intelligence in our universe, it is a given that we do have life and intelligent beings on our own beautiful blue planet. Simply facing the prospect that life as we know it, and intelligent beings, as we know them, may be a very rare occurrence underlines the importance of treating the thin scum of life on the surface of our world with tremendous respect.

As well, it forces us to recognize how precious our own being is – collectively and individually.  Notions such as the right to life for each and every person, the right to equality under the law for all persons, and so on, become reinforced by this remarkable scientific blank page – that as far as we know we are the only part of the universe that is aware of itself – and while there may be many logical reasons, using probability theory or quantum theory or whatever – to speculate that there may be life and intelligence teeming “out there” – in fact for all we really know, we are “it’ .

From this perspective we are “the pearl of great value“ (Matthew 13: 45-46, New Testament) for which the “finder” of this pearl has sacrificed everything he or she has in order to obtain that pearl of great value.

In this respect some revelations of pre-scientific religions overtake science, at least as it relates to our relative place on the earth and in the cosmos. For example, the teaching of Hinduism or Bhuddism that require tremendous respect for other forms of life – even reverence – are reinforced by the more recently acquired knowledge that our existence and that of all living things on earth is based on a very fragile, interdependent ecosystem.

The Christian teaching that each person is a child of God – an heir to the kingdom – again is reinforced by  everything we learn about our selves, our relationships in societies, and by the continuing expansion of our knowledge of the universe. Many physicists seem to be resigned  to respond to the wondrous, immense, incredible universe we are constantly discovering with the feeling that we, as humans, are inconsequential – a random, rare fluctuation – like a Boltzmann Brain.

In fact many of the conceptions of BB’s referred to in physics refer to the BB’s as observers only – that is, randomly fluctuating into existence and able only to observe a universe  somewhat like we observe – presumably with somewhat different paradigms, but the same laws of physics operating. The reference to Sean Carroll where he states that BB’s are “cognitively unstable’ is typical of notions I have seen in reference to BB’s.

What seems to be missing in regarding BB’s and Ordinary Observers like Ourselves (OO’s in Page’s language) is such things as feelings or relationships. Perhaps items like emotions and feelings would be dismissed by some of the thinkers on this topic as just particular arrangements of data in our brains, or something like that. Nevertheless, in my own opinion, the most likely feeling or emotion in any randomly occurring BB would be profound loneliness.

In contrast, in our own situation we exist in symbiotic relationship with a vast host of living things in addition to other human beings. We have evidently evolved within this background host and live with it in an interdependent way, the details of which we are still discovering.

The most straightforward answer to Fermi’s question of “Where is everybody ?“ is –  “We are here, here and now – 7 or 8 billion of us.” And of course we could also mention the teeming web of life that forms the fabric on which our own existence depends. From there, we can grow to understand and act on the Christian foundation of loving our neighbours as much as we love ourselves, sharing not only the bounty of our earth with one another but also the wonderful ideas, discoveries and insights that our Ordinary Observer brains have been able to experience.


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