{"id":3514985,"date":"2025-07-23T10:23:24","date_gmt":"2025-07-23T10:23:24","guid":{"rendered":"https:\/\/www.resilience.org\/?p=3514985"},"modified":"2025-07-23T10:24:29","modified_gmt":"2025-07-23T10:24:29","slug":"what-is-life","status":"publish","type":"post","link":"https:\/\/www.resilience.org\/stories\/2025-07-23\/what-is-life\/","title":{"rendered":"What is Life?"},"content":{"rendered":"

No doubt about it: Life is truly amazing. I mean, the things it gets up to far exceed our imaginations! (Just watch a few dozen Ze Frank \u201cTrue Facts<\/a>\u201d videos to scratch the surface.) It hardly seems necessary to invest in a post to elucidate what constitutes Life, when a small child will correctly identify instances almost every time. Living beings demonstrate awareness about their surroundings, taking actions broadly in service of goals to thrive and reproduce. An amoeba marks itself as alive because we witness its purposeful mobility to secure food and evade danger.<\/p>\n

Yet, living beings are undeniably made of atoms\u2014atoms that do not appear in any close investigation to operate outside the usual rules of physics. Our sensation of awareness, experience of color perception, etc. seems so far removed from physics that the intractable connection is obvious to neither child nor adult. How could this awareness (what we label \u201cconsciousness\u201d)\u00a0possibly<\/em>\u00a0arise out of inanimate particles obeying physics without some \u201cspecial sauce\u201d unavailable to mere \u201cmachines\u201d like computers or robots? It seems\u00a0prima facie<\/em>\u00a0absurd, so it requires an unusual suspension of disbelief to submit to the baffling prospect.<\/p>\n

How is it even possible, though, that inanimate matter can constitute Life? In a word:\u00a0feedback<\/strong>.\u00a0Life is feedback<\/em>. The sun is of huge importance to Life, but we would not say that it is\u00a0alive<\/em>\u00a0itself even though it actively engages with the universe and is a critical contributor to living beings on Earth. It\u2019s continuance as a star is not contingent on these interactions. No feedback loop makes fusion in the core care what happens in Las Vegas. As an aside, I resist dividing lines and include the Sun (and everything else) in a living whole: just try doing without it!<\/p>\n

Feedback Makes Things Cool<\/h3>\n

I often taught a course for physics majors that had them build\u2014in teams of two or three\u2014a working device whose parameters were pretty wide-open. It needed to sense\/measure something in the real world, process that information in some way, then act\u00a0back<\/em>\u00a0on the real world in response\u2014usually in a way that altered whatever measurement was being made. This is called feedback: \u201cHmmm: the signal is stronger in this direction, so I\u2019ll move toward it; even stronger now!\u201d The explosion of creativity that emerged was a delight\u2014and a lesson in itself. Each year, about half the projects reminded me of projects from previous years, but another half would be totally new\/original. One recurrent theme was a little motorized wheeled thingy (car) that could roam around and perhaps ignore obstacles, stay within taped lines, navigate a maze, move scattered objects to a collection point, or track down a target\u2014sometimes a combination of these elements. But we also had one-off devices that sorted marbles by color, mixed cocktails perfectly (college kids), threw a ping-pong-ball into a cup (still college kids), tip-tilted a table to navigate a camera-tracked marble through a maze, pulsed and colored a spinning \u201csphere\u201d of LEDs in response to tones and volume of ambient music, maintained an inverted pendulum via camera feedback\u2014and loads of other fun, creative ideas. [Before my time at UCSD, Mike Judge of Beavis\/Butthead fame went through the same class as a physics major.]<\/p>\n

As a warm-up exercise, I would have students build a pair of light sensors on a moving wand, the goal being to have the wand point toward light. It also employed a proximity sensor to keep the wand from running into anything. Even in this well-defined domain, I was perpetually surprised by how much behavioral variety emerged. Depending on sensor arrangement, electronic conditioning, and unconstrained choices on how they coded the decision tree, each one had its own\u00a0personality<\/strong>. You might think I\u2019m being glib about that word, but I swear those things would often make me laugh when I \u201ctested\u201d them out. Sometimes their reaction was super-skittish when I would move my hand close, and it would take a while before they would tentatively creep back toward the light and that big scary obstacle that might still be there. Others seemed aggressive. Some were jittery, while others smooth and relaxed. The odd duck was a bit loopy and hard to characterize. Relatedly, our chickens with walnut-sized-brains had\u00a0tremendous<\/em>\u00a0and distinct personalities: the bar for personality isn\u2019t terribly high.<\/p>\n

The projects demonstrated that sensing and feedback is all it takes for a machine to mimic some (tiny sliver) of the behaviors of Life. Yet while important, that\u2019s not the form of feedback of primary concern here.<\/p>\n

Awareness and Reaction<\/h3>\n

Before I get to the feedback that\u00a0really<\/em>\u00a0makes Life incredible, I want to discuss awareness and reaction. The student projects tended to have some form of awareness (sensing) and made decisions (reacted) accordingly\u2014sometimes displaying baffling behaviors that neither I nor the designers\/coders could explain. Occasionally unexpected bugs became valuable features that redirected the aims of the project in fun ways.<\/p>\n

Awareness is at the core of what we call consciousness. I\u2019m often \u201con about\u201d consciousness because of our culture\u2019s tendency to elevate it to a grand, transcendent state in classic\u00a0human-supremacist<\/a>\u00a0(and dualist) fashion\u2014set apart from the mundane elements of the universe. Having such sophisticated cranial hardware\u2014a prefrontal cortex and all\u2014gives us more of this neural connectedness and awareness (of our brian\u2019s workings\u2014or thoughts\u2014for instance) than is the case for most creatures. It is, therefore, this particular quality we select as a definition of superiority: we pretend it\u2019s a game\/competition then write the rules to ensure we \u201cwin.\u201d<\/p>\n

I dismiss the notion of any \u201cquantum\u201d leap in awareness, putting humans on one side of a sharp line. The property appears to track cranial complexity, but even exists to\u00a0some<\/em>\u00a0degree in the absence of brains or neurons. Most of the many-millions of species on Earth don\u2019t bother with neurons, yet still require awareness and reactivity to operate, learn, and survive. Microbes sense food gradients, toxicity gradients, light gradients, etc. and move according to their changing needs. Plants sense water, nutrients, light, and configure accordingly. They also sense infestation and warn others nearby to ready defenses.<\/p>\n

Thus, if we must use the word \u201cconsciousness,\u201d then extending the privilege to any form of Life, however brainless, seems the least we could do. It\u2019s a continuum of complexity, all apparently rooted in material interactions. Anyone who disagrees can try thinking their objection without complete dependence on matter and energy (arranged appropriately). No one has yet succeeded in that challenge.<\/p>\n

Transition States<\/h3>\n

In another important waypoint en route to the main point, let\u2019s look at seeds and spores. As discussed in a closely parallel post called\u00a0Decisions, Decisions<\/a>, seeds can remain dormant and viable for\u00a0tens of thousands of years<\/a>\u00a0and spores for\u00a0hundreds of\u00a0millions<\/em>\u00a0of years<\/a>! All that time, they maintain a sort of vigilant awareness of their environment. Yet, they do so without a nanojoule of metabolic expenditure, without neurons, without tiring. (I would venture that what ultimately disables them is a random high-energy particle\u2014from cosmic rays or terrestrial radioactivity\u2014destroying a critical atomic arrangement; more likely to occur for larger, more complex seeds than tiny-target spores.) The patient \u201cawareness\u201d of seeds and spores is more easily traced to a \u201cmechanistic\u201d origin of receptors essentially spring-loaded to effect a change when ambient conditions and resources warrant (opening channels for ion flow). Seeds and spores unable to make \u201cgood\u201d decisions in this sense never get folded into successful lineages.<\/p>\n

All the Way Down<\/h3>\n

As a final illustrative example, we\u2019ll consider the electron\u2014as a familiar example of a fundamental particle. An electron is \u201caware\u201d\u2014to varying intensities\u2014of every other charge in the universe (in its causal \u201clight cone<\/a>\u201c), constantly reacting. Similar to how a microbe might move in reaction to a sensed food gradient, an electron moves according to the gradient of electric potential. The fact that it obeys strict rules\u00a0every single time<\/em>\u00a0does not in any way preclude complex behavior that is effectively unpredictable and \u201csensitive\u201d (try the most difficult level of the\u00a0electric field hockey game<\/a>; I\u2019ve managed legitimate navigation using 6 placed charges\u2014or 3 in a \u201cloophole\u201d cheat).<\/p>\n

So, being aware of its surroundings and reacting accordingly, would we say that electrons are\u00a0conscious<\/em>? I suppose I can\u2019t stop anyone from doing so, but it seems inappropriate in the usual sense of the word. The electron is just doing as it must in reaction to its surroundings\u2014in complete, constrained compliance with the laws of physics.<\/p>\n

Ah: but if I yank the privileged term from electrons, then surely spores deserve the same revocation: they \u201cjust\u201d have some physics-based receptor that will trigger when the appropriate molecules come in contact. Well, then, the microbe is decked with sensors and structured in such a way that signals on this particular channel stimulate this kind of response. It\u2019s still using the same rules of physics (elaborated to the level of chemistry and biology), just in a far more sophisticated way that quickly\/easily exceeds our limited comprehension. By the time we have the full self-replicating microbe, we are\u00a0FAR<\/em>\u00a0beyond the level of sophistication achievable by our engineering efforts.<\/p>\n

So it goes with plants, fungi, mollusks, worms, frogs, hawks, skunks, and humans. Increasing layers of complexity\u2014conspicuously expressed in hardware<\/strong>\u00a0(!!<\/strong>)\u2014permit increasing levels of awareness and complex reaction. By the time we get to human-like brains, the prefrontal cortex is wired in contact with many other parts of the brain\u00a0explicitly<\/em>\u00a0to exercise some balancing\/management of potentially competing impulses. Thus part of our organism becomes \u201caware\u201d of (some subset of) our internal processes\u2026and we call this \u201cmagic\u201d (transcendence) in the absence of complete understanding\u2014which I\u2019d bet we never acquire.<\/p>\n

All this to say: if one wants apply the term \u201cconsciousness\u201d to humans, then be prepared to extend the courtesy all the way to elementary particles\u2014which by definition lack constituent parts such as neurons. If no sharp distinctions exist on the continuum, then either all individual particles and collection of particles have (transcendent) consciousness, or none do at all. I prefer the latter, as the original intent of the word obviously becomes stretched to the absurd at the electron level (also fruitful to muse about the free will of an electron, which is so well-behaved as to require no transcendent qualities). I don\u2019t at all mean to imply that because no dividing line exists on the continuum from electrons to humans,\u00a0both<\/em>\u00a0have the\u00a0same level<\/em>\u00a0of awareness: that would be absurd and not at all consistent with material complexity. I just suggest that the spectrum is one of vast differences in\u00a0complexity<\/em>, lacking an ontological gap.<\/p>\n

What is it that\u2019s so scary about recognizing what we call consciousness as the experience facilitated by a remarkably sophisticated arrangement of matter operating by nothing other than physics? Why not marvel? I\u2019ll tell you this right now: no one has a shred of evidence contradicting this unified description of how everything\u2014including Life\u2014works, while corresponding physical structures are ubiquitously found as compelling circumstantial\/forensic evidence.<\/p>\n

Back to Feedback<\/h3>\n

I previously dangled the notion that\u00a0some<\/em>\u00a0aspect of feedback separates Life from inanimate matter. So which is it: all the same stuff, or something transcendent?<\/p>\n

Yes to both, in a mundane sort of way. I would put forth that it\u2019s all the same matter obeying all the same rules of interaction (in fact, no choice otherwise\u2014raising the spectre of\u00a0determinism<\/a>\u00a0that some constitutions cannot mentally abide). What makes Life unique is\u00a0feedback on performance<\/strong>. It\u2019s the painfully simple but unimaginably powerful concept behind evolution. Viable organisms propagate their genetic instructions to future organisms. Non-viable organisms don\u2019t stick around.<\/p>\n

What this means is that the amoeba whose reaction to a food gradient is to move in the direction of higher food concentration fares better, so whatever trial coding told it to do that is passed down. That\u2019s the basic story, repeated and amplified and honed in billions of different ways. The fly that lifts off before the horse tail slaps down will remain a fly and make other flies with the correct decision-wiring to automatically evade a fatal slap. Life exhibits proactive, purposeful action because it could not exist any other way. The idea that it manages to do so within a material context is all the more impressive to me.<\/p>\n

Practically speaking, Life boils down to electromagnetic interactions (gravity and nuclear forces hardly shaped the origins of Life) executing a stupendously rich dance according to molecular structures and vanilla physics. It would appear to have no other choice: no violations have ever been noted.<\/p>\n

The \u201cmagic\u201d happens precisely\u00a0because<\/em>\u00a0of this selection feedback. An electron responds to a defined gradient in potential in a fully predictable manner. Life, however, can surprise us (our stripped-down mental models) purely based on the complexity of relevant interactions.<\/p>\n

The light-seeking, collision-avoiding wands students built in my class might execute surprising behaviors, but lacked an essential ingredient: the ones I saw were not proven to be reproductively viable in a tangled ecological context. Nothing we build is. No computer, AI platform, helicopter, etc. has the staggering burden of making decisions impacting its viability to remain in the world, and thus come off as empty executors of deliberately de-complexified (debugged, \u201clobotomized\u201d) code. The quirks of the wands were effectively random, based on arbitrary component properties, physical arrangements, and coding decisions made by the students. When it comes to Life, every quirk has consequences and thus a deep story: a reason it serves the being well (enough), in its context.<\/p>\n

The\u00a0post on rivulets<\/a>\u00a0offers a case of inanimate but adaptive, reinforcing decision-making. Rivulets are an example of success-based feedback for self-replicating structures whose initial \u201crandom\u201d decisions are selected for fitness so that surviving rivulets appear to have the magic sauce to make \u201csmart\u201d decisions. Though brain-busting complexity sits between mature rivulets and penguins, the fundamentals are not wholly unbridgeable: both are selected to make the kinds of decisions that allow them to survive. That doesn\u2019t diminish the penguin\u2019s amazingness in any way. For me, it serves to inspire even greater awe at the outcome.<\/p>\n

What is Life?<\/h3>\n

Our universe may be one of a multitude\u2014as experimentally-motivated cosmologies and landscape string theories promote. Whether or not this is true, our particular universe has a particular (very small) set of fundamental particles and a rich set of interactions between them (the primary story is\u00a0interactions<\/em>, not the bit-player particles). Arbitrary combinations of mass ratios, relative strengths of the fundamental forces, vacuum energy, symmetries, etc. are exceedingly unlikely to produce even atoms or complex chemistry, let alone galaxies, stars, and planets. We\u2019re in the lucky sort of universe that\u00a0can<\/em>\u00a0make stars and truck on for billions of years. Belief in luck isn\u2019t actually required, as our being in the \u201cright\u201d sort of universe represents an unavoidable and major\u00a0selection effect<\/a>.<\/p>\n

So, what is Life? To me, it\u2019s a staggeringly impressive trick that the universe\u00a0can<\/strong>\u00a0perform, playing by the normal rules utilizing the normal material. Wow. Lucky us! When something\u00a0can<\/em>\u00a0happen, we ought not be\u00a0too<\/em>\u00a0surprised when it\u00a0does<\/em>\u00a0somewhere in a vast and ancient universe\u2014especially when that surprise traces to a lack of our own capacity to pin down how it happens.<\/p>\n","protected":false},"excerpt":{"rendered":"

So, what is Life? To me, it\u2019s a staggeringly impressive trick that the universe\u00a0can\u00a0perform, playing by the normal rules utilizing the normal material. Wow. Lucky us!<\/p>\n","protected":false},"author":128238,"featured_media":3514988,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[79718,213530,79720],"tags":[],"class_list":["post-3514985","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-environment","category-environment-featured","category-society"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.resilience.org\/wp-json\/wp\/v2\/posts\/3514985","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.resilience.org\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.resilience.org\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.resilience.org\/wp-json\/wp\/v2\/users\/128238"}],"replies":[{"embeddable":true,"href":"https:\/\/www.resilience.org\/wp-json\/wp\/v2\/comments?post=3514985"}],"version-history":[{"count":3,"href":"https:\/\/www.resilience.org\/wp-json\/wp\/v2\/posts\/3514985\/revisions"}],"predecessor-version":[{"id":3514989,"href":"https:\/\/www.resilience.org\/wp-json\/wp\/v2\/posts\/3514985\/revisions\/3514989"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.resilience.org\/wp-json\/wp\/v2\/media\/3514988"}],"wp:attachment":[{"href":"https:\/\/www.resilience.org\/wp-json\/wp\/v2\/media?parent=3514985"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.resilience.org\/wp-json\/wp\/v2\/categories?post=3514985"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.resilience.org\/wp-json\/wp\/v2\/tags?post=3514985"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}