Edit: I have to give part of my last point back to Rosenberg, the one about the anthropic principle. As it happens, his criticism of the anthropic principle(s) applies mostly to the definitions of Barrow and Tipler, while my conflicting description of it is the version of Carter, in which the anthropic principle is just a selection bias. Most of what I know about the anthropic principle, I have read in Lee Smolin’s excellent books. I am now reading Ideas that Matter by A.C. Grayling, in which he puts the different definitions against one another. However, there is no question of a multiverse in the original definitions by Barrow and Tipler the definitions Rosenberg is targeting. In these definitions, the laws of physics and our place and time in the Universe are just determined so that we can be here. The version with the multiverse explains the laws of physics as a selection bias, which is not what Barrow and Tipler do. Rosenberg is still confused about the anthropic principle, but so was I.
The American Freethought podcast featured an interview with Alex Rosenberg a few weeks ago. Rosenberg is the R. Taylor Cole Professor of Philosophy at Duke University, author of many book, respectable fella. The interview was about Rosenberg’s latest book, entitled The Atheist’s Guide to Reality. John and David had a very lengthy and interesting discussion with Rosenberg which sparked my interest in the book. The book exposes reality as it is seen by the eyes of science, and it takes a courageous and honest look at the best answers that we have to the “big” questions such as “what is the purpose of life?”
In order to do this, Rosenberg procedes to review the fundamental facts of physics and biology, and this is where it all goes wrong. I was going through the chapter where he describes physics. I put down the book in the middle of the chapter completely baffled by the many inaccuracies. Having spent a lot of time listening to and reading people like Lee Smolin, Brian Greene, Stephen Hawking, Richard Feynman, Neil deGrasse Tyson, Bill Nye, Sean Caroll, Steven Weinberg, Phil Plait, and all the professors I ever had throughout my physics education and all the speakers I have seen in colloquia, seminars and conferences, I had a hard time believing someone like Rosenberg could get so many things wrong. All these people I just referred to all agree on the basic facts that Rosenberg get wrong. He obviously didn’t do his homework.
This post isn’t an exhaustive list of the inaccuracies in the book since I haven’t read it all. At this point, I don’t think I will read it all. I may come back to it at some point when I have built up some tolerance for inaccurately reported and made up facts in my field, but it won’t happen tomorrow. Let’s get to it.
The cosmic microwave background points to the center of the Universe
In the words of Rosenberg himself:
“In any direction we point microwave detectors, the amount they detect is always the same except for one small region of slightly greater intensity-the source of the big bang.”
This gets my blood boiling. Rosenberg refers to the cosmic microwave background, about which we know a tremendous lot thanks to WMAP and other observatories. Let’s have a look at the cosmic microwave background.
Rosenberg talks about intensity, but the variations you see in this picture are not in intensity. WMAP, the satellite that took this data, was not designed to measure variations in intensity but in wavelength (which translates directly to temperature via the laws of blackbody radiation). Intensity and wavelength are two different things, and to the best of my knowledge, there has been no intensity map made of the cosmic microwave background.
Let’s say Rosenberg was mistaken and he meant that there is a spot in the cosmic microwave background emitting a bit more energy (which WMAP could recognize by seeing shorter wavelengths). We can see such a spot on the right of the image, but can it really point to the center of the universe or “the source of the big bang”?
We understand the patterns in the cosmic microwave background fairly well, and that you see a spot more evident than the others on this map is expected. It would even be expected if the fluctuations in wavelength were perfectly random. Randomness generate clusters, not uniformity. One of these clusters is bound to be more evident than the others. We really cannot attribute any special significance to the spot we see in the middle right of the image.
But there is another reason why this statement is just so wrong. The big bang happens everywhere is space simultaneously. It has no source, and there is no such thing as the center of the Universe. That Rosenberg ignores this astounds me. Here is Phil Plait explaining this.
We have been empirically testing what happens before the big bang
Here is how Rosenberg phrases it:
“One remarkable thing about this best current cosmological theory is the degree to which physicists have been able to subject it to many empirical tests, including tests of its claims about things that happened even before the big bang […]”
The best current cosmological theory is the Cosmological Standard Model, or the Lambda – Cold Dark Matter model. Lambda refers to dark energy. The thing is, the Cosmological Standard Model doesn’t even pretend to predict anything before the big bang.
The big bang is often thought as being the emergence of space and time. From this interpretation, the phrase “before the big bang” doesn’t even make sense. The Cosmological Standard Model consists of 6 parameters and the Friedmann-Lemaître-Robertson-Walker metric which you put into the theoretical framework of general relativity. What you get by cranking out the consequences of putting these things together is the best understanding we have so far of the evolution of the Universe since the big bang. It also predicts that the big bang is a causal horizon, the same way the event horizon of black holes are causal horizons. No information can possibly get through causal horizons by definition. This is why we can probably never empirically test predictions about the Universe “before the big bang”. There are a number of exotic models out there that make predictions about what lies outside the Universe, and what happened before our Universe, but these models can hardly be called the best cosmological theories we have.
The LHC was built to study the big bang
This one is a half-truth. In the words of Rosenberg:
“[…] physicists decided to risk several billion euros on the Large Hadron Collider at CERN (the European Organization for Nuclear Research), outside Geneva, to test the big bang theory directly by creating the very conditions that occurred just after the big bang”
The main goal of the LHC is not to do cosmology. We are not testing the big bang here, we are fairly convinced it happened. It doesn’t really need more evidence. However, we do want a more complete picture of what happened. The main goal of the LHC is to generate collisions in which we will definitely see the Higgs boson, the quanta of the Higgs field, if it exists. The Higgs boson does have large implications on cosmology, but the motivation to look for it doesn’t come from cosmology.
There are 3 fundamental forces that play at the scales of fundamental particles. Weinberg, Glashow and Salam got the Nobel Prize for figuring out that two of these forces are actually the same and can be described using the same theory. These two forces are the electromagnetic force and the weak nuclear force, and the reason we think they look different in the Universe today is because of the Higgs field.
At the kind of energies you would find just after the big bang, particles are colliding with such strength that the effect of the Higgs field does not matter, and the electromagnetic and weak nuclear forces look one and the same. As the Universe expands and cool down, particles start feeling the effects of the Higgs field and some particles interact more strongly with it than others. Interacting with the Higgs field is equivalent to having a mass, as the field is everywhere, and your interaction with it is constant wherever you are. This is what we want to study at the LHC, as it could very well be the origin of the mass of all fundamental particles.
The anthropic principle doesn’t help understanding anything (and it is used by religious apologists)
This one makes me completely nuts. I cannot believe a philosopher would get the anthropic principle wrong. Here is what Rosenberg think it is:
“Why did the multiverse come into being? So that the universe could come into being. Why did the universe come into being? In order to produce us. And of course we know who arranged matters this way, blessed be his name.”
This is completely backwards. First of all, there are multiple versions of the anthropic principle, and at least one of them helps us understand why we exist at all. When understood properly, it forces us into humility in the face of the cosmos. The weak version of the principle answers the following questions quite correctly. Why is the Earth so hospitable to human life? Why is the Earth just the right distance from the sun all year long to bear liquid water? Why does it have a breathable atmosphere? Why is it so rich chemically?
The answer comes by looking at the stars; the stars in our galaxy, the stars in other galaxies. We have recently discovered that a lot of these stars have planets. Given the trillions of observable stars in the Universe (and potentially many more we can’t observe), we can assume that they don’t all have identical systems of planets. However unlikely it is to have an Earth-like planet around Sun-like stars, if you have large enough quantities of stars, you are bound to find a few of them with this configuration. However unlikely it is that life emerges on one of these planets, if you have enough of these planets you will find life. However unlikely it is that life evolves an intelligent species, if you have enough planets with life you will find one.
This is the anthropic principle. It relies on large numbers to explain the occurrence of very rare and special events. Why do some people win the lottery even if only 1 person in 10 million win? Because more than 10 million people play. The strong anthropic principle says that the Universe has the physical laws that it has because there are just enough universes in the multiverse to make it probable that one of them has these laws. And we are forcibly going to find ourselves in this universe. Of course, we don’t really know that there is a multiverse, but this is looking more and more like a reasonable assumption.
There is nothing theistic at all about the anthropic principle. Stephen Hawking and Leonard Mlodinow make use of it in The Grand Design to do away with the necessity of God to explain the Universe.
So there it is. You now know why I am extremely suspicious of Rosenberg, and why I lack the enthusiasm to finish his book. This information he gets wrong is only one google search away. It’s all on Wikipedia! I cannot trust anyone who doesn’t have the reflex to check the facts he puts down in his book, especially if these facts are not part of his specialty. It looks like Rosenberg was confident enough about his own knowledge of physics to just go ahead and explain what he thinks he knows with the full force of his authority. I call this arrogance and I object.