Victor Stenger’s Redefinition of Nothing
March 5, 2012
Physicist, and author of “God the Failed Hypothesis”, Victor Stenger, suggests that quantum mechanics is the reason why there is something rather than nothing. I would like to explain some of the reasons why his reasoning is not convincing to me.
Why is there something rather than nothing?
Everyone of us who wants to live an examined life asks themselves this question at some point. For theists, that the universe exists makes good sense. But take away God, and I’m totally unsure why the universe should exist at all. I don’t know why the beautiful physics of this universe should take place. Why not nothing? Nothing at all – with no properties, no physics, no nothing. Why doesn’t the universe (along with us in it) simply not exist?
I have seen many unsatisfying responses by atheists to this question. Here, for example Peter Atkins arguing that the universe itself is actually “nothing”.
Things with properties, such as you and I, the earth, atoms and electrons, photons, electric and magnetic fields, sticky tape and the woman next door are not nothing. Peter Atkins reasoning fails. He is equivocating. He’s redefining “nothing” in a way which is convenient for himself, but has a different meaning to the question. For anyone genuinely searching for an answer, that is incredibly unsatisfying (if not dishonest) way to answer the question.
Victor Stenger’s redefinition of nothing
Victor Stenger redefines what is meant by “nothing”. Instead of meaning…. well nothing, he redefines it as the vacuum state of a quantum field. He writes,
This suggests a more precise definition of nothing…
After which he treats the words “nothing” and “vacuum state” as synonymous. Immediately he runs into exactly the same problem as Peter Atkins. This isn’t what people are asking when they ask why there is something rather than nothing. The question is not why we’re not in the vacuum state, but why there’s a quantum field (or indeed, anything at all) in the first place.
To plug the growing gap (and seemingly obvious equivocation) between the question and his answer Victor Stenger assures his readers that the vacuum state is, in fact, the same as nothing. He says,
Nothing [the vacuum state] is a state that is the simplest of all conceivable states. It has no mass, no energy, no space, no time, no spin, no bosons, no fermions—nothing.
A vaccuum state doesn’t have no energy
In his attempt to defend his definition, Stenger appears claim the vacuum state has no energy. That’s simply wrong, and I can only assume he made a typo. He rightly tells his readers the exact opposite only a few short paragraphs before,
Stepping down the ladder you find that the bottom rung corresponding to a field of zero photons is not zero energy but rather E/2.
So energy is one property which vacuum state does have. Quantum fields (of a particular frequency) do have a ground state whose energy is
A particular mode also has a corresponding frequency related to the energy by the above equations. Having parameters to describe both its energy and frequency, it is hard to see how a vacuum state is the same as “nothing”.
Phase and amplitude
There are other important properties of the vacuum state which Stenger conveniently doesn’t mention. Let me explain.
Quantum mechanics only makes predictions about the probabilities of measurements (such as whether a photon is or isn’t detected at a dector). We describe the possible outcomes of an experiment with the wavefunction. Born’s rule says that the amplitude squared of the wavefunction gives the probability of a given outcome, and so quantum mechanics just tells us a set of probabilities for outcomes of different experiments. This uncertainty manifests itself in funny ways. Famously Heisenberg’s uncertainty principle says that if you know position of a particle, its momentum will be less certain and vice-versa. There are many similar relationships in quantum mechanics (in fact for any non-commuting variables there’s a similar expression). The equivalent for light is the amplitude (how bright the light is) and the phase (where the dips and peaks are). You can’t measure both the amplitude and phase of light at the same time.
Even for field in the vacuum state, it has these uncertainties. We can manipulate these probability distributions, but we always have to obey the uncertainty principle. For a particle it’s possible to become more certain about where a particle is, but only at the of becoming less certain we can be about its momentum. Similarly, in quantum optics, the more certain we are about light’s amplitude, the less certain we are about its phase. These are properties even of the vacuum state, and properties which can and have been manipulated in the lab.
These can even be and have been manipulated in experiment. The top trace here, is from a vacuum state, and the third is from a phase squeezed vacuum state. That is, we have good knowledge of where the peaks and troughs are, but not how so much information about how big they are.
A vacuum state measurable consequences
There’s a strange effect which relies on the vacuum state which you might have heard of. If two objects are near each other, they attract each other. They do so because of the standing waves which are set up between them. It turns out that if they move together they actually lower the total energy. And so, there’s an attractive force (because, like a ball rolling down a hill, two ships will try to move together to reduce their potential energy).
The is true of quantum mechanics, and has been observed. Two objects near each other set up standing waves between them, and feel an attractive force. This effect is known as Casimir effect. This effect occurs precisely because there are standing waves between the two objects. If these didn’t exist, there would be no force. In other words, if, instead of a standing wave, there was nothing between the objects, you’d expect no force. But in reality, you do measure a force in the lab, precisely because the field described by the vacuum state is not nothing.
Why Stenger’s answer isn’t satisfying
Stenger has redefined the word “nothing” to suit his answer, but in a way which makes a mockery of both the question, and of the science. The vacuum state (of a particular quantum field) is a particular quantum state, it has properties, such as an energy, a corresponding frequency. It also has uncertainties in both amplitude and phase quadratures which can be measured and manipulated in experiment. The vacuum state plays a fundamental role in the Casimir force between two objects. Stenger’s redefinition makes two very different beasts the same thing. Like Atkins, it is convenient for Stenger to redefine words to suit his cause. But when he does that, he answers a question nobody is asking.
That is why I find Victor Stenger’s answer to why there is something rather than nothing so unsatisfying.
As always comments are welcome and criticism is encouraged!