### Book Review: A Universe From Nothing

A couple of days ago I was lent a copy of Lawrence Krauss' book "A Universe From Nothing" and having been previously very critical of Krauss, I've decided I couldn't resist writing a review of my immediate thoughts on the book.

Already I'm taken aback by the somewhat ridiculous afterword written by Richard Dawkins when he says that "If On the Origin of Species was biology's deadliest blow to supernaturalism, we may come to see A Universe From Nothing as the equivalent from cosmology."

Are we really going to compare what was arguably the most crucial publication in the advancement of biology ever in its history, with a book that doesn't propose anything original or new and that dabbles in speculative and untested (possibly untestable) physics? Well I guess we are.

Chapters 2-7

This is the best part of the book, it both recants much of the history of cosmology–from the viewpoint of what Krauss was working on–and some quantum mechanics. This much is largely well written and I commend these chapters to anyone interested in astronomy and astrophysics.

The book starts out as a nice popularization of many aspects of cosmology, it describes the evidence Cosmologists have that convince them that our universe is filled with dark matter (Tyson's simulation weighing galaxies with gravitational lensing, Fritz Zwicky's calculations in the 1930s and the observation of galaxy rotation) and dark energy (largely from the BOOMERanG experiments and the observed acceleration of the universe). It also ties in well with the modern discoveries about the local topology of the universe, which at times Krauss understandably but wrongly equates to the geometry of the universe.

These discoveries accumulate to what cosmologists refer to as the "LCDM model" of cosmology and its so far stood up against all the data we have, including the most recent test, that being the 2015 Planck data published after Krauss' book.

Chapter 8 is roughly when Krauss makes the transition from known physics, to what he thinks is the best explanation for the initial conditions of the LCDM model, namely eternal inflation. Unfortunately Krauss' description of the universe which emerges from a false vacuum as 'nothing' is set up for confusion; a lot of people who read this description are likely to go away confused or disappointed when they realize he hasn't actually addressed the subtitle of his book. Namely 'why does something exist, rather than nothing?'

Rather than using the term "nothing" as a negation, which is what almost everyone means by the term, Krauss insists on treating it as the subject of a sentence or perhaps the object of a statement. This is just a semantic quibble not a very impressive argument and Krauss manages to draw it out to fill in the last three chapters of the book.

On the one hand Krauss uses nothing to refer to particles popping out of "empty" space in several physical theories, e.g. Hawking radiation, the quantum processes which produced the dominance of matter over antimatter, the casimer effect, inflationary theory where energy density is conserved instead of mass-energy.

• $E(t) = \rho V(t)$

While on the other, he argues that even this vacuum can arise from a deeper kind of 'nothing'. Referring to speculative models in quantum cosmology, like the Hartle-Hawking model or Vilenkin's tunneling model. It's simply wrong to refer to the Harlte-Hawking model (which is eternal) as coming from nothing. I've tried to explain in some way both of these proposals on this blog already, so I won't repeat myself here. In short, Krauss' remarks to have solved Leibniz's quandary are dead wrong and his religious critics who fight over the issue are absolutely right, the question is unanswered and probably unanswerable.

You can explain the evolution of the quantum state at one time with fields and no particles, to a state with particles perfectly well and consistent with a set of known laws but that still leaves a lot of questions unanswered. Referring to that prior state of space, time, fields, laws of physics and so forth as "nothing" doesn't help much.

Whether you refer to "something" as "nothing" it only misleads; it doesn't answer the problem of why anything at all exists. One can still ask why do the laws of quantum mechanics exist, why does the quantum vacuum exist, or why does the wave function 'exist'?

Krauss continues that inflation, which could have produced a multiverse may also vary many of the constants, parameters and masses of fundamental particles in accord with the $10^{500}$ possible variations of those parameters in string theory. Eternal inflation is a sensible proposal but most cosmologists aren't as a certain about the multiverse as Krauss appears, the model is not based on known physics.

There's no global description of eternal inflation like there is of our local universe in the FRW standard model; Friedman's equations assume large scale homogeneity which is violated in eternal inflation. Moreover eternal inflation is a quantum process, it can't happen in ordinary general relativity, the quantum effects which drive inflation carry energy and therefore must alter Einstein's background solution, how do you correct this back-reaction effect? I don't believe either of these questions can be answered without postulating some new physics.

It seems also to have a pretty serious measure problem $P= e^{S}$ where $S =1/\Lambda$ and this is largely neglected in the book, and for what its worth, its certainly not the only game in town, as far as string cosmology goes, other models like pre-Big Bang inflation or the Ekpyrotic Cyclic scenario are at least still possible.

In the last section of the book, Krauss speculates more about a quantum origin of 'eternal' inflation but doesn't go much into the history of quantum cosmology, he only briefly mentions the field in chapter 11 but the history is fascinating. The foundations of the field were set by John Wheeler and Bryce DeWitt in the 1960s and seminal ideas about the quantum origins of the universe (or rather its material content) began as early as 1973 with Edward Tryon.

More speculative ideas about the quantum origins of spacetime itself began emerging in 1982 by Atkatz and Pagels and 1982 by Vilenkin, and then the famous Hartle-Hawking proposal in 1983.

I'm also now tempted to comment on the preface of Krauss' book, therein includes the unpleasant ad hominem that "philosophers and theologians are the experts on nothing". In my experience its only a relatively small number of physicists who disparage or derogate entirely, in their way of thinking from philosophy and those who do are apt to misunderstanding.

Philosophy is the science of all things, it is in essence the use of reasoning and rational thought to come to conclusions about a conceptual space of ideas which are not open to empirical testing. If all you're interested in is science, the study of the empirical world, then no, you probably don't need philosophy.

However, if you want to understand the way the world is, or even nature of physics-related problems like the nature of the wave function, the interpretation of quantum mechanics, the problem(s) of time, then philosophy is important.

Scientific theories are often filled with philosophical questions and its wrong to judge the philosophy of science by what contribution or advancements it makes to science (as Krauss does). Philosophers of science are largely not even attempting to address scientific problems any more than historians of science or sociologists of science. Their discipline is to advance the philosophy of science, not science itself.

My main objection to this book however isn't that its anti-philosophy, speculative or even sometimes draws conclusions which are overstated, or even that its off centered for a science book it talks relatively, a lot of ammeter theology. The problem is the main edifice of the book, to explain "why" anything at all exists in terms of scientific theories, is not even wrong. If what Krauss says is true he's only explained one physical state in terms of some prior physical state. The fundamental mystery indicated in the subtitle of the book remains at large.

### William Lane Craig and the Hartle-Hawking No Boundary Proposal

Classical standard hot Big Bang cosmology represents the universe as beginning from a singular dense point, with no prior description or explanation of classical spacetime. Quantum cosmology is different in that it replaces the initial singularity with a description in accord with some law the "quantum mechanical wave function of the universe", different approaches to quantum cosmology differ in their appeal either to describe the origin of the material content of the universe e.g., Tyron 1973, Linde 1983a, Krauss 2012 or the origin of spacetime itself e.g., Vilenkin 1982, Linde 1983b, Hartle-Hawking 1983, Vilenkin 1984.

These last few proposals by Vilenkin, Hartle-Hawking and others are solutions to the Wheeler-DeWitt equation and exist in a category of proposals called "quantum gravity cosmologies" which make cosmic applications of an approach to quantum gravity called "closed dynamic triangulation" or CDT (also known as Euclidean quantum gravity). I&#…

### How Should Thatcherites Remember the '80s?

Every now and again, when I talk to people about the '80s I'm told that it was a time of unhinged selfishness, that somehow or other we learned the price of everything but the value of nothing. I can just remember that infamous line from Billy Elliot; 'Merry Christmas Maggie Thatcher. We all celebrate today because its one day closer to your death'. If it reflected the general mood of the time, one might wonder how it is she won, not one but three elections.

In an era when a woman couldn't be Prime Minister and a working-class radical would never lead the Conservative party, Thatcher was both and her launch into power was almost accidental owing in part to Manchester liberals and the Winter of Discontent. Yet I'm convinced her election victory in '79 was the only one that ever truly mattered. Simply consider the calamity of what preceded it, the 1970s was a decade of double-digit inflation, power cuts, mass strikes, price and income controls, and the three…

### Creation Of Universes from Nothing

The above paper "Creation of Universes from Nothing" was published in 1982, which was subsequently followed up in 1984 by a paper titled "Quantum Creation of Universes". I decided it would be a good idea to talk about these proposals, since last time I talked about the Hartle-Hawking model which was, as it turns out, inspired by the above work.
Alexander Vilenkin also explains in a non-technical way the essential idea in his book; Many World's in One – one of the best books I've ever read – it mostly covers cosmic inflationary theory but the 17th chapter covers how inflation may have begun. In fact Vilenkin is one of the main preponderant who helped develop inflation along with Steinhardt, Guth, Hawking, Starobinsky, Linde and others.
Although I won't talk about it here, Vilenkin also discovered a way of doing cosmology by using something called "topological defects" and he has been known for work he's done on cosmic strings, too.
In ex…