Category Archives: Science

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

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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.

It’s Not the Reactionaries So Much as the Elites They Listen To

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Twitter isn’t the best place for reasoned discussion, but depending on who you follow, it isn’t a vast, superficial wasteland either. One of the cool things it offers is the occasional tweetstorm that benefits from directness and immediacy.

Here, slightly edited, is what David Roberts, who writes about climate and energy for Vox, had to say in thirty or so tweets yesterday:

Ever since climate became a political issue in the US, one of the most ubiquitous topics of climate discussion has been “how can conservatives be persuaded to accept climate science and join in the productive search for solutions?” I have read, no joke, MILLIONS of words on that subject. Been following that conversation long enough to notice it has certain recurring features.

The weirdest aspect is that it almost always treats conservatives and their denial as a kind of feature of the landscape, like a mountain. It’s something that just IS, something other people have to maneuver around, or overcome, or otherwise deal with. It is not treated as a CHOICE, made by grown-ass adults who could choose differently, for which they are responsible.

Another (related) weird aspect is, it’s almost always treated as something that the right’s political opponents *caused*. Al Gore caused it. Strident rhetoric or “alarmism” caused it. Enviro aversion to nuclear power (or CCS [Carbon Capture and Storage], or geoengineering) caused it.

It’s always discussed as a result of something enviros or the left did–and something they could undo, if they just acted/talked right. “If environmentalists stopped doing [thing that personally annoys me], they’d be winning over the right” is a *ubiquitous* template.

But it’s bullshit. The question of what shapes conservative opinion is not some deep mystery about which your gut impulses carry any insight. It’s an intensely studied question in social science and has been, as least to a decent approximation, answered. I recommend this post, summarizing John Zaller’s book The Nature & Origins of Mass Opinion. To *very* briefly summarize: people don’t know anything; they don’t have strong opinions on political “issues”; they form opinions by following the cues of leaders in their various social tribes. We are social creatures; tribal ties (not “issues”) are primary.

So conservatives believe what conservatives believe. And they find out what conservatives believe from conservative elites.That means conservative politicians, celebs, and local leaders, but especially, in US conservatism circa 2017, *media figures*. Conservative media plays an *enormous* role in shaping conservative opinion and has dragged it steadily rightward.

So we can say with confidence that conservatives deny climate change because that’s what conservative political/media elites do. Elite cues are what matter. It follows that the *only* reliable way to get conservatives to stop denying climate change is for conservative political/media elites to stop. That’s it.

You might think that Al Gore should STFU, enviros should support nuclear, green journalists should avoid “doomism” and all the other things that VSPs [Very Serious Persons] are always scolding greens for. Fine. Think what you want. Scold away.

But there is no evidence, and no reason to think, that any of those changes would have any material effect on conservative climate denialism. Conservatives will change their tune on climate when the people they see on Fox & Breitbart change their tune. Until then, clever arguments and magic words (“national security!” “conserving God’s gift!”) are futile for everything except meeting think-piece word counts.

Conservative elites and media are to blame for conservative ignorance and obstruction on climate. Not greens, not Democrats, not Al Gore, not That Guy on Twitter. What they are doing is a monstrous crime that will directly result in enormous suffering. And they are grown-ass adults fully capable of understanding the consequences. They are responsible for their own actions and deserve to be called out for them.

Basically, conservative elites are to blame for climate paralysis and only conservative elites can change it. I don’t like it, but there it is. Step one for everyone ought to be telling the damn truth about it. Quit finding “clever,” “counterintuitive” ways to blame others, FFS. As Ornstein and Mann said (more broadly, but it applies here as well), “Republicans are the problem”.

Of course, in the case of global warming, Republicans are only part of the problem. The big problem is global warming itself, combined with how unlikely it is that we will stop it from getting worse. What scientists have predicted for decades is coming to pass. The world is getting hotter; the atmosphere has more moisture in it; the oceans are rising; the ice is receding; the permafrost is melting; storms and heat waves are intensifying. We are polluting the planet to a dangerous degree and it’s coming back to bite us, too quickly for us to stop it, yet too slowly to make everyone feel the urgency of the problem. 

Later, I saw that David Roberts presented his thoughts more formally in an article with a long title: “As Hurricanes and Wildfires Rage, US Climate Politics Enters the Realm of Farce: Climate Denial Is Less Credible, But More Powerful, Than Ever”.

But if you want to get really depressed, take a look at The Guardian‘s “This Is How Your World Could End”. If the author is correct, it’s not out of the question that the earth’s surface may become too hot for mammals. The good news is that many other living things would survive, including birds, who handle heat better than we do.

Time Travel: A History by James Gleick

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There are two principal topics in this book: time travel and time. Since time travel is fiction, the history of time travel presented in the book is the history of ideas about time travel, mostly ideas expressed in novels like H. G. Wells’s The Time Machine, short stories like Robert Heinlein’s “By His Bootstraps” and movies like The Terminator. Time travel can be fun to think about, and ideas about time travel are suggestive of what people have thought about time, but I quickly lost interest in the topic. So I ended up skimming those sections of the book.

On the other hand, Gleick’s discussion of time itself was worth reading. He covers both physics and philosophy, and does an excellent job explaining complex, competing ideas about time. For example:

You can say Einstein discovered that the universe is a four-dimensional space-time continuum. But it’s better to say, more modestly, Einstein discovered that we can describe the universe as a four-dimensional space-time continuum and that such a model enables physicists to calculate almost everything, with astounding exactitude, in certain limited domains. Call it space-time for the convenience of reasoning….

You can say the equations of physics make no distinction between past and future, between forward and backward in time. But if you do, you are averting your gaze from the phenomena dearest to our hearts. You leave for another day or another department the puzzles of evolution, memory, consciousness, life itself. Elementary processes may be reversible; complex processes are not. In the world of things, time’s arrow is always flying.

It’s an interesting question whether the calculations of the physicists are so accurate because the universe really is a four-dimensional space-time continuum. And is the passage of time some kind of illusion, like many physicists believe? Gleick leans toward time being quite real and physicists taking their models a bit too seriously. I think this would have been a better book if he spent more time on the physics and philosophy and less time on the fiction.

Darkness in America

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I suppose it’s possible there were some “very fine people” who chose to march with the Nazis and Klan in Charlottesville, chanting “blood and soil” and “Jews will not replace us”. Perhaps they were seriously misinformed about the nature of the event. But as Chris Rock said today: “If 10 guys thinks it’s ok to hang with 1 Nazi then they just became 11 Nazis”.

The good news is that the president* sunk so low today that more of our fellow citizens will turn against him, finally seeing him for what he is. His angry defense of white supremacy even generated disgusted reactions from a few of the right-wingers on Fox (order has probably been restored by now).

Congresswoman Gwen Moore, a Democratic Congresswoman who represents Milwaukee, called for his impeachment:

“As we once again hear [the president*] defend those responsible for the deadly riot in Charlottesville and receive praise by hate groups like the KKK and neo-Nazis, the time has come for Republicans and Democrats to put aside our political differences and philosophical debates for a higher cause. For the sake of the soul of our country, we must come together to restore our national dignity that has been robbed by [his] presence in the White House. My Republican friends, I implore you to work with us within our capacity as elected officials to remove this man as our commander-in-chief and help us move forward from this dark period in our nation’s history.”

Of course, impeachment is unlikely, given the Republican majority in the House, but perhaps the House and Senate will vote to censure him. I could see our not-as-terrible-as-some Republican Congressman voting for that. 

Perhaps being censured would finally give our president* the heart attack or stroke he so richly deserves (after his new chief of staff told him what “censure” means). 

Meanwhile, the sun, earth and moon are speeding toward the locations in space that will give America a solar eclipse on Monday. The “totality – the area where the sun is completely blocked by the moon – will be 70 miles wide and will travel from Oregon in the morning to South Carolina in the afternoon. The rest of the country will see a partial eclipse. 

Vox has a cool eclipse tracker that allows you to see when the eclipse will occur in your zip code and how much of the sun will be hidden. At its peak here in New Jersey, 72% of the sun will be hidden at 2:44 p.m. I don’t plan to use the special glass or glasses you need in order to avoid permanent eye damage, but I’ll certainly take a quick look. Coincidentally, I have an appointment with our optometrist at 3 p.m. I can experience the eclipse from his parking lot and then he can tell me if I’m blind.

I’m just brainstorming here, but I wonder if someone could convince our president* that the eclipse will be a Message telling him his presidency is over. Eclipses have often made a big impression on the ignorant and/or simple-minded. Assuming he’s in Washington, however, the moon will only block 81% of the sun. That might not be enough. But the Secret Service could tell him he’s got a rally to attend in South Carolina (they like him down there) and arrange him to be outside at just the right time. It’s a long shot, but one can dream.

PS: Another Democratic Congresswoman, Jackie Speier, who represents the area south of San Francisco, has called for the president* to be removed because he is mentally unfit: “[He] is showing signs of erratic behavior and mental instability that place the country in grave danger. Time to invoke the 25th Amendment”.

Consciousness As Mental, As Physical

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It’s been argued that a scientist who grew up in a black and white room and never saw the color red could learn everything there is to know about the physics of light and the physiology of the human body, including what happens in the brain when someone sees red, but not know what red looks like. Presumably, a blind scientist with the same training would be in the very same position. Likewise, a deaf scientist could know everything about the physics and physiology involved in hearing a violin but not really know what a violin sounds like. This is supposed to show that there is something in the universe beyond the reach of the physical sciences: the mysterious mental phenomenon of consciousness.

“Mental” is a word I haven’t used much (or at all) in writing about consciousness, yet consciousness is clearly a mental phenomenon if anything is. But what does it mean for a phenomenon to be “mental”?

The obvious answer, although it’s not very helpful, is that “mental” means “not physical”. But what does that mean?

An exchange of letters I referred to last month between the philosopher Thomas Nagel and a professor of bioengineering, Roy Black, tries to deal with the question. Prof. Black criticizes the idea that “nonphysical factors” are involved in consciousness:

As is frequently noted, the physical basis of life itself used to be just as mysterious as consciousness, and it’s now well explained by biochemistry and molecular biology, without nonphysical factors. So although science as we know it doesn’t explain the link between neurons and consciousness, why expect the link to be “nonphysical” rather than “novel physical”? What is a nonphysical factor, anyway? If the dark energy propelling the expansion of the universe, the strong force holding atomic nuclei together, etc., etc., are physical, do we really need anything more exotic?

… Lots of things in biology—like the development of an organism from an egg—seem impossible, until we stretch our imagination to conceive of simple precursors and mechanisms that could have been worked on by natural selection over billions of years. To quote one of [the philosopher Daniel Dennett’s] nice lines, “evolution is a process that depends on amplifying things that almost never happen.” We need to determine what “thing,” what activity of neurons beyond activating other neurons, was amplified to the point that consciousness arose. What would a precursor of “feeling like” be? That’s what we need to stretch our imaginations further to figure out.

Prof. Nagel responds, but his response is based on an assumption:

The difficulty is that conscious experience has an essentially subjective character—what it is like for its subject, from the inside—that purely physical processes do not share [how does he know this?]. Physical concepts describe the world as it is in itself, and not for any conscious subject….

I agree with Black that “we need to determine what ‘thing’, what activity of neurons beyond activating other neurons, was amplified to the point that consciousness arose.” But I believe this will require that we attribute to neurons, and perhaps to still more basic physical things and processes, some properties that in the right combination are capable of constituting subjects of experience like ourselves, to whom sunsets and chocolate and violins look and taste and sound as they do. These, if they are ever discovered, will not be physical properties, because physical properties, however sophisticated and complex, characterize only the order of the world extended in space and time, not how things appear from any particular point of view [again, how does he know this?].

Nagel’s assumption is that a purely physical process cannot have a subjective character (it cannot “feel like something”). It cannot be “how things appear” from a particular point of view. But if consciousness is a physical process, it does have a subjective character. In that case, how things feel or appear are indeed physical properties of a process that occurs in space and time (it happens inside your head when you’re conscious).

Here’s my take on the mental/physical distinction. Nobody knows what the universe contains at the most fundamental level (or if there is a most fundamental level). But suppose that quantum field theory is correct and, quoting Prof. David Tong of Cambridge University (who I wrote about earlier this year):

The best theories we have tell us that the fundamental building blocks of nature are not particles but something much more nebulous and abstract. The fundamental building blocks of nature are fluid-like substances which are spread throughout the entire universe and ripple in strange and interesting ways. That’s the fundamental reality in which we live. These fluid-like substances, we have a name for, we call them “fields”.

Furthermore, when the fields ripple or are agitated in certain ways, we get sub-atomic particles. An electron, for example, is a kind of ripple in the electron field.

So when I say that consciousness is a physical process, what I’m saying is that consciousness is at bottom constructed from one or more quantum-level fields – or whatever the fundamental building blocks of the universe are – that somehow interact with the quantum-level fields – or other building blocks – from which everything else in the universe is constructed. Maybe consciousness involves a kind of fundamental field that physicists can’t measure or detect yet. Maybe it involves a new kind of interaction between fundamental fields that physicists already know about.

But consciousness seems to be part of the natural world in the same way other physical phenomena are. And because it’s part of the natural world – not a kind of free-floating spiritual or supernatural substance or phenomenon – consciousness can represent other physical events and processes outside itself. Consciousness being part of the world is why we can be consciously aware of our bodies and the world around us.

“Mental”, therefore, refers to what happens in our minds, but at bottom mental phenomena are physical phenomena. Consciousness, like gravity, digestion and baseball, is one of the things that happens in the world. In other words, the “mental” is a subset of the “physical”. Or so it seems to me.