Reality Is Not What It Seems: The Journey to Quantum Gravity by Carlo Rovelli

Carlo Rovelli is an Italian theoretical physicist whose previous book, Seven Brief Lessons on Physics, was a bestseller. In this one, he tells a familiar story: the history of physics from ancient Greece to the present day. But he tells it in such a charming and enlightening way that the story feels new.

One of the lessons from the book that will stick with me is that, according to current physics, the universe isn’t infinitely divisible. At some point, you’ll get to the bottom where the quanta (or tiniest pieces) are. The surprising part of that idea is that these quanta apparently include the quanta or tiny pieces of spacetime. But these tiniest pieces of spacetime aren’t in space or time. They compose space and time. Here’s how he sums it up at the end of the book:


The world is more extraordinary and profound than any of the fables told by our forefathers…. It is a world that does not exist in space and does not develop in time. A world made up solely of interacting quantum fields, the swarming of which generates — through a dense network of reciprocal interactions — space, time, particles, waves and light….



A world without infinity, where the infinitely small does not exist, because there is a minimum scale to this teeming, beneath which there is nothing. Quanta of space mingle with the foam of spacetime, and the structure of things is born from reciprocal information that weaves the correlations among the regions of the world. A world that we know how to describe with a set of equations. Perhaps to be corrected.


The biggest puzzle Rovelli and his colleagues are working on is how to reconcile the small-scale physics of quantum mechanics and the large-scale physics of general relativity. They aren’t consistent. Currently, the most popular way to resolve the inconsistency is string theory, but Rovelli’s preferred solution is loop quantum gravity. Unfortunately, his explanation of loop quantum gravity was the part of the book where he lost me. Maybe a second or third or fifteenth reading of that section would clear things up.

The other idea that will stick with me is from quantum field theory: among the fields that make up reality, such as the electron field and the Higgs boson field, is the gravitational field. But the gravitational field is just another name for spacetime. Spacetime is the gravitational field and vice versa. That’s what Rovelli claims anyway, although he ends the book by pointing out that all scientific conclusions are open to revision given new evidence and insights.

The Metaphysics and Ethics of Relativism by Carol Rovane

I would have to read this book at least one more time in order to feel confident about summarizing the conclusions the author reaches. However, here’s my impression after reading it once. As I understand her aims, Carol Rovane wants to clearly explain what relativism is with respect to science and ethics, and then determine whether we should endorse relativism with respect to either of those domains.

She begins by criticizing what she calls “the prevailing, consensus view” of relativism, which she says relies on the idea of disagreement. This is the idea that relativism arises “with a certain kind of disagreement that is said to be, first of all, ‘irresoluble’ [i.e. unsolvable], but also, second, ‘irresoluble’ for the specific reason that both parties are right” [15-16]. Rovane prefers defining relativism in terms of alternatives, which may or may not involve disagreement, and which are themselves explainable in terms of “normative insularity”.

According to Rovane, relativists believe that some alternative views in science or ethics are cut off from other scientific or ethical views. Logic neither “mandates, licenses or prohibits” inferences between them, so two people can hold alternative views about science or ethics and logic has nothing to say about the alternatives [94]. It’s as if, metaphorically speaking, people can occupy different scientific or ethical worlds. Non-relativists, on the other hand, believe that all truth bearers are logically related, either directly or indirectly. My scientific views aren’t insulated from your scientific views, and your ethical views aren’t insulated from mine. We all occupy the same scientific world and the same ethical world.

Rovane goes so far as to label the non-relativist and relativist positions in terms of how many “worlds” they mandate. What she calls “unimundialism” is the non-relativistic view that there is only one world (in which there is no “normative insularity” between propositions in science or ethics). “Multimundialism” is the relativistic view that there are many worlds (in which there is “normative insularity” between some scientific or ethical propositions). 

I think the conclusion she reaches is that scientific theories apply to a single world, so it’s best not to think of science in unimundial or non-relativistic terms. Reality is one, so alternative scientific theories can’t be equally correct. But unlike scientists, who all study the same world, people grow up and live their daily lives in various social conditions. These social conditions help determine which behavior is morally correct for them. Rovane thinks it’s fair to say, therefore, metaphorically speaking, that people inhabit different ethical worlds depending on their particular social conditions. Hence, multimundialism or relativism is an acceptable view with respect to ethics.

To help justify her relativistic conclusion regarding ethics, Rovane asks us to imagine two women. One woman was brought up in Europe or America and accepts the ethical importance of autonomy, i.e. every individual’s right to make their way in the world according to their own needs and desires while respecting the needs and desires of other people. The other woman was brought up in a village in India and sincerely believes she has an ethical obligation to obey her parents, even if it means giving up her right to pursue her own needs and desires.  Rovane argues that these two women live in very different ethical worlds. Their societies are so different when it comes to ethical issues that each woman is acting ethically, even though they are following very different paths and choosing to obey very different ethical principles.

A Guide to Reality, Part 3

Continuing to work through The Atheist’s Guide to Reality by Alex Rosenberg:

Professor Rosenberg begins chapter 1 by explaining why he’s not going to spend much time arguing for atheism: others, especially David Hume, have already done that quite well; such arguments, even very good ones, don’t convince true believers; and anyway, it’s more important to understand how science can help us live without illusions than to keep talking about religion.

Instead, Rosenberg is going to discuss a view called “scientism”. As he notes, “scientism” is usually applied in a negative way to people who supposedly worship science, or try to extend it beyond its natural borders, or simply take it too seriously. Rosenberg welcomes the term, defining it this way:

[Scientism] is the conviction that the methods of science are the only reliable ways to secure knowledge of anything; that science’s description of the world is correct in its fundamentals; and that when “complete”, what science tells us will not be surprisingly different from what it tells us today (6-7).

The idea that the current scientific description of the word is fundamentally accurate is known among philosophers as “scientific realism”. The Stanford Encyclopedia of Philosophy defines it as “a positive epistemic attitude towards the content of our best [scientific] theories and models, recommending belief in both observable and unobservable aspects of the world described by the sciences”. In other words, science is a highly reliable way to acquire knowledge of the world. Science allows us to learn about the world as it is, independent of our minds. Science even allows us to find out about things we can’t directly observe, like the Big Bang and sub-atomic particles.

Rosenberg is clearly a scientific realist. Not all philosophers are (they, in fact, disagree to some extent about what science is). But Rosenberg’s scientism goes beyond simple scientific realism when he asserts that “the methods of science are the only reliable ways to secure knowledge of anything”.

Maybe he’s exaggerating on purpose (not something philosophers ordinarily do), but are you and I doing science when we look out the window and agree that it’s snowing? Is a student doing science when she concludes that Socrates was mortal if Socrates was a man and all men are mortal? As Rosenberg knows, of course, science relies on occasionally unreliable activities like seeing and hearing in order to gather evidence. Even though scientists don’t rely on a single person’s observations, they do use the same perceptual abilities the rest of us employ to acquire knowledge. In addition, most of us would agree that people clearly know lots of things that aren’t “scientific” in the usual sense (including math, logic, historical facts, cultural practices and whether the Ford is in the driveway).

Perhaps it’s enough that an adherent of scientism believes that, when applied correctly, the various methods of science are by far the best ways we have to get at the truth about many or most features of the world. Those methods include classification, observation, experimentation, measurement, replication, discussion, publication and other things physicists, chemists, biologists and psychologists regularly do.That seems right to me, but I don’t think it’s enough for Rosenberg.

Before moving on, I should mention that Rosenberg also considers this question: if science is such a reliable method of determining the truth, why do so many people reject scientific conclusions? One reason, of course, is that scientific results are often revised. Another is that scientists often disagree among themselves, especially on topics that make the news, in some cases because they are influenced by un-scientific factors, like working for Exxon. Yet another big reason why many are skeptical about science is that scientific conclusions often make people uncomfortable (as in the case of climate change, for example).

Rosenberg, however, mainly discusses the human need for “stories”, by which he means our tendency to understand the world in terms of personalities and purposes. He argues that our ancestors became good at recognizing and interpreting purposeful behavior because that skill made it much easier to live and prosper among other people. Evolution, however, overshot the mark. People heard thunder and concluded that Someone was angry. Today, according to Rosenberg, people have trouble understanding math and physics because their subject matter doesn’t include human beings or other creatures doing things. In other words, science is especially hard because most people haven’t been built (through evolution) to understand it. Religion, on the other hand, often involves stories, which we generally find more easy to understand than science.

In the next installment: physics and the nature of reality.

A Guide to Reality, Part 2

A couple days ago, I stated my intention (you might even say I promised) to work through Alex Rosenberg’s The Atheist’s Guide to Reality: Enjoying Life Without IIlusions right here at WOCS. That was in part 1. Believe it or not, this is part 2.

In his preface, Professor Rosenberg explains that he wrote the book for people who are ready to face reality. By that he means people who believe there is no God (atheists) or have serious doubts (agnostics) and who want to know what science has to say about a few perennial questions that keep some of us awake at night. He thinks the scientific view of reality has certain consequences:

The book is about those consequences. It provides an uncompromising, hard-boiled, no-nonsense, unsentimental view of the nature of reality, the purpose of things, the meaning of life, the trajectory of human history, morality and mortality, the will, the mind and the self (ix).

Rosenberg scoffs at attempts to reconcile science and religion. He holds that “an unblinking scientific worldview requires atheism” (viii), which explains why most of America’s leading scientists are atheists and those who aren’t atheists are mostly agnostics.

I don’t think it makes any difference to Rosenberg whether science leads us to atheism or atheism leads us to science. He started out in physics, ended up in philosophy, branched out to biology and economics, and somewhere along the way became an atheist. But someone might proceed in the other direction: doubting God’s existence and then looking to science to explain why the world is the way it is. His contention is that science and atheism are compatible, while science and religion (or theism) aren’t.

In my opinion, however, he exaggerates the conflict. You don’t have to deny God’s existence in order to be an excellent scientist. Instead, what you need to do is put thoughts of God aside when you’re doing science. Science is the search for natural explanations, not supernatural ones. Invoking God as the explanation for the existence of the human eye, for example, amounts to throwing up your hands and choosing a different subject. If you want to speculate about some god or other creating the universe and initializing the fundamental constants (like the mass of an electron) to values supportive of life, you’re not doing science. In this methodological sense, a scientist has to be an atheist.

But despite what Rosenberg says, nobody knows why or how the universe came into existence; or if it’s always existed in some form or other; or whether our universe is one of many. Even if scientists eventually figure out the answers to those questions, we’ll never be able to rule out the possibility that some creator or creative force beyond our universe got the cosmic ball rolling. Nor will we ever be able to prove that God, Zeus or Santa Claus isn’t watching right now to see if we’ve been naughty or nice. What evidence could there be to prove that kind of negative?

What we can say is that, historically speaking, science has shown a vast number of previously mysterious phenomena to be natural processes. There is no reason to think we need an entity outside space and time to explain why there are stars and galaxies, or why there are birds and bees, or why the Red Sox sold Babe Ruth. As fewer phenomena have seemed to require a supernatural explanation, it has seemed less and less likely that there is Anyone Up There. As we’ve learned more about our world, ancient stories have become much less plausible. So far as science is concerned, God is a dead letter.

But that doesn’t necessarily mean God is dead, however implausible that he, she, it or they either are or ever were “alive”.

Next time: stories and scientism.

The Great Agnostic: Robert Ingersoll and American Freethought by Susan Jacoby

According to The Great Agnostic, there were two great opponents of religion and proponents of naturalism in American history: Thomas Paine and Robert Ingersoll. Strangely, hardly anyone today has heard of Ingersoll. (For that matter, few Americans today know that Tom Paine had anything to say about religion.)

Robert Ingersoll was a world-famous lawyer and lecturer who lived from 1833 to 1899. He was considered perhaps the greatest orator of his day. He had an extremely successful career traveling all across the country, lecturing to large, appreciative crowds, among whom were many ordinary, religious Americans. He was a member of the social and political establishment, but his public statements opposing religion insured that he never held political office.

In Susan Jacoby’s words, Ingersoll “explained the true meaning and value of science … in a more understandable fashion than any scientist, even the brilliant popularizer Thomas Henry Huxley … Second, Ingersoll made the connection between repressive religion and everyday burdens and injustices as no one had before him.” 

Among the targets of Ingersoll’s scorn were slavery, capital punishment, the subjugation of women, debtor’s prisons, the mistreatment of animal and Social Darwinism. He believed that “there were no social injustices in which religion did not play a major role” — for example, in the belief that the existence of the poor was God’s will, and the idea that men should exert authority over women. 

Jacoby suggests that Ingersoll’s primary purpose was to remind his countrymen that the United States was founded by men who rejected the idea of theocracy: “the glory of the founding generation was that it did not establish a Christian nation”. Ingersoll rejected all supernatural explanations for human behavior and the world around us, while hoping that science and reason would eventually lead us to a world of peace, justice and prosperity. Quoting him: “Man through his intelligence must protect himself. He gets no help from any other world…. Let the ghosts go. We will worship them no more”.

Ingersoll came to be known as the “Great Agnostic”, even though he saw no significant difference between agnosticism and atheism. It isn’t clear why his fame diminished over the years. Although his collected works comprise 12 volumes, perhaps his written words weren’t as powerful as his oratory. Maybe if he had written a good summary of his views, he would be as famous today as Thomas Paine is for writing “The Age of Reason” (which, unfortunately, isn’t very famous at all).

One of the virtues of The Great Agnostic is how it shows that our current cultural battles over religion are hardly new. The 19th century featured the same kinds of conflict, on topics like evolution, birth control and government support for religious education. We haven’t made as much progress as we should have. If there had been someone with Ingersoll’s convictions and abilities speaking out during the 20th century, and now in the 21st, we might be a better country today.