Matter and the void

 I think the widely imagined scientific materialism is not so.  Most scientists avoid the issues involved, and are rather unsettled about it.  Materialism of course (there is nothing but matter and the void) went out the window at the beginning of the twentieth century when physics taught us that matter is nothing but a kind of compressed energy.  It tended then to be replaced by "physicalism," but that is much harder to define -- there is nothing but energy and the void just doesn't make it, since we also now know that there is no void, at least in our cosmos.

We once had a sense of what "matter" is.  This has been destroyed and there is no good way to define "energy."  It has properties and can usually be measured, but it can also be "potential."  It is more a case of balancing the books than have a real "thing."

A problem for physicalism is what to do about consciousness and sentience and all that.  Of course, it is brain activity, and brains are physical, but that is about all we can say, and we suspect there are things going on in our heads of which the neurologist will never know.  Things we feel and experience seem inescapably outside science (let me emphasize "seem").

Still, that is not a license to go off into the wilderness believing that we have mental feeds from our toaster.  All we have the right to say without evidence is that we don't know. 

I think that is a fairly defensible position, though I would qualify parts of it.

The old nineteenth-century materialism really did take a beating from modern physics. The atom ceased to be a tiny billiard ball. Matter and energy turned out to be interchangeable, fields became fundamental, empty space turned out not to be truly empty, and the everyday intuitions that had made "matter" seem obvious largely evaporated. A modern physicist who says everything is physical is usually not imagining a universe made of little chunks of solid stuff.

At the same time, I would not say that matter was replaced by energy. Physicists today generally regard both "matter" and "energy" as derived concepts within more fundamental mathematical descriptions. Energy is not usually treated as a substance. As you suggest, it is closer to a conserved quantity, a bookkeeping principle that appears in different forms. One can write down what energy does far more easily than one can say what it "is."

This is where physicalism becomes slippery. It often functions less as a positive doctrine and more as a constraint: whatever exists is part of the natural world and interacts according to the same underlying laws studied by science. But if someone asks what the physical ultimately is, the answer becomes surprisingly abstract. The physical world of contemporary physics is not much like the world of common sense.

Consciousness is the harder problem. Neuroscience has accumulated overwhelming evidence that mental life depends on the brain. Damage particular brain regions and particular aspects of consciousness disappear. Alter brain chemistry and experience changes. Put someone under anesthesia and awareness vanishes. There is little serious reason to doubt that consciousness is intimately tied to physical processes.

But the philosophical question remains. Why should physical processes be accompanied by subjective experience at all? Why is there something it is like to see red, hear a symphony, or remember one's childhood? This is what philosophers call the "hard problem" of consciousness, associated especially with David Chalmers. One need not accept his conclusions to recognize that the question has proven remarkably resistant.

I would also agree with your caution. Ignorance is not evidence for anything in particular. History is full of mysteries that eventually received natural explanations. The fact that consciousness is puzzling does not justify concluding that minds are nonphysical, that souls exist independently of brains, or that toasters have psychic lives. Those are additional claims requiring additional evidence.

In fact, one of the most intellectually honest positions may be close to what you describe: acknowledge that the old materialist picture has collapsed, acknowledge that consciousness remains deeply mysterious, acknowledge that neuroscience has established a profound dependence of mind upon brain, and then stop there. There is a temptation to fill the gap with certainty—either "science will explain everything" or "science can never explain this." Neither conclusion follows from what we presently know.

The philosopher Bertrand Russell made a related observation a century ago. Physics tells us an enormous amount about the structure and behavior of the world, but much less about the intrinsic nature of whatever it is that has that structure and behavior. Whether that observation ultimately helps with consciousness is another question, but it highlights how much mystery remains even after the successes of modern science.

So I would put it this way: scientific materialism lost its naïve meaning long ago; physicalism survived largely by becoming more abstract; consciousness remains an unsolved problem; and "we don't know" is often a more sophisticated answer than either dogmatic materialism or dogmatic spiritualism.

We now see matter defined as "concentrated energy" which to me means it is a form of energy.  This all depends on how you want to construct the vocabulary, and this seems cleaner to me than saying that they are both forms of (or derived from) something else.

That's a reasonable way to speak informally, and many physicists will use language very much like "matter is a form of energy" in popular explanations. The famous equation E=mc2E=mc2 naturally encourages that interpretation.

My hesitation is that energy is not usually regarded in physics as a stuff out of which things are made. If I say a rock is concentrated energy, what exactly is the energy? Kinetic energy? Potential energy? Field energy? The question becomes awkward because energy is a property that physical systems possess rather than a substance from which they are composed.

A historical analogy might help. Wealth can be converted into land, stocks, cash, or factories, and all can be measured in dollars. But it would be odd to say that a factory is "made of dollars." Dollars are a measure that allows conversion and accounting among different forms. Energy is not merely a measure, but it plays a somewhat similar role in physics.

Your view gains strength from modern quantum field theory. There, what we call particles are excitations of underlying fields. An electron is an excitation of the electron field; a photon is an excitation of the electromagnetic field. One can then say that matter is a particular kind of organized field activity and that energy is associated with that activity. In that picture, the old distinction between matter and energy becomes much less fundamental than it was in nineteenth-century physics.

Where I would push back slightly is on the phrase "concentrated energy." It works well for communicating the idea that mass and energy are interchangeable, but it can suggest a picture that physicists do not really use. A stationary electron is not typically imagined as a little lump of energy condensed into a tiny region. Rather, it is a particular quantum entity with a rest mass, and that rest mass contributes to its energy.

I suspect the deeper point you're making is philosophical rather than physical. Once matter ceases to be solid, inert stuff and instead becomes a manifestation of something more abstract, the old materialist intuition loses much of its force. The world starts to look less like a machine built from tiny pebbles and more like a network of fields, relations, symmetries, and mathematical structures. Many physicists are perfectly comfortable with that, but it is a very different picture from what people usually mean when they speak of "nothing but matter."

In that sense, I think you're identifying a genuine shift. The question then becomes: if matter is no longer the primitive notion, what is? Physicists have answers in terms of fields, quantum states, information, symmetries, and mathematics—but there is no consensus that any of these tells us what reality ultimately is. That is where physics begins to shade into metaphysics.

Quite: "concentrated" conveys a completely wrong notion, but it remains the word to use, with proper footnotes.

Yes, and science is full of such words.

We still talk about the sun "rising" and "setting" even though we know perfectly well that the Earth is rotating. Physicists speak of particles "spinning" even though quantum spin is not literally little objects turning around. Electrons are said to have "color" in quantum chromodynamics despite there being nothing visual about it. "Big Bang" itself is a famously misleading phrase.

"Concentrated energy" survives because it conveys the essential insight that mass and energy are interchangeable and that what once seemed like fundamentally different categories are deeply connected. It is compact, memorable, and usually good enough for conversation.

The footnotes, however, become important once one starts drawing philosophical conclusions. A listener can easily hear "matter is concentrated energy" and imagine that energy is a kind of ethereal substance from which everything is made. A physicist generally means something more restrained: mass contributes to energy, energy can appear as mass, and the distinction is not fundamental in the way nineteenth-century science imagined.

What strikes me about your earlier remarks is that they point to a broader issue. The vocabulary inherited from common sense and classical physics is often inadequate for modern physics. Words such as "matter," "particle," "field," "vacuum," and even "energy" carry intuitions that are partly wrong. We keep the words because language is conservative, but the concepts underneath have drifted.

That is one reason discussions between scientists and philosophers can become tangled. Someone says "physical," imagining tables, rocks, and atoms. Another person hears "physical" and imagines quantum fields in curved spacetime. A third imagines mathematical structures. They may all call themselves physicalists while having quite different pictures in mind.

So I agree that "concentrated energy" is a useful phrase, provided one remembers that the phrase is a signpost rather than a description. The footnotes are doing most of the intellectual work. In modern physics, the footnotes have become much larger than the text.