The seven characteristics of life from biology class, the one-line definition of life that 123 definitions boil down to, NASA's working definition, why fire isn't alive, what makes something alive in physics (dissipative structures, a heated dish, the Belousov reaction), whether life breaks the second law of thermodynamics (Schrödinger's What Is Life?), whether viruses are alive, and how life began on Earth (abiogenesis).
The full answer
What is life?
What is life? Physics gives a good answer, that life is chemistry that keeps itself organized by running energy through it, and copies itself before the pattern falls apart. I'm Justin Hartfield, I've spent twenty-five years in cannabis, and the biologist who taught me this said you can't understand illness without knowing what life is.
What are the 7 characteristics of life?
What are the seven characteristics of life? Biology class gives you a list: living things are organized, take in energy, grow, respond, keep their insides steady, reproduce and evolve.
In 2011, the biologist Edward Trifonov boiled a hundred and twenty-three definitions of life down to one line, that life is self-reproduction with variations. NASA's working definition is close, a self-sustaining chemical system capable of Darwinian evolution.
Is fire alive?
Is fire alive? A fire gets a long way down that list, taking in fuel and growing as it spreads. But a flame can't pass on how it's built, so every new fire starts from scratch and dies when its fuel runs out.
What makes something alive?
So what makes something alive, if a flame comes that close? I go by one man's framework.
In 2010 I met a biologist named Bob Melamede. He changed how I saw everything I'd built. He had a picture for this. Life is a whirlpool. It only exists while energy flows through it.
Picture a thin layer of oil in a dish, heated from below. At first the heat just creeps up through it. Turn it up a little more, and the oil sorts itself into hexagons, warm rising in some places and cool sinking in others.
Billions of molecules started moving together because moving together carries the heat away faster. Completely unarranged, yet somehow totally synchronized.
That dish is a game in the film, so you can turn up the heat yourself and find the band where hexagons appear.
Too little flow and nothing happens, and too much tears the pattern apart. Life lives in the band between.
Does life break the second law of thermodynamics?
Does life break the second law of thermodynamics? It doesn't, though the law says disorder always grows overall, and in 1944 the physicist Erwin Schrödinger explained how. A living thing feeds on what he called negative entropy, staying ordered inside by pushing even more disorder out as heat and waste.
Now check out this chemical mixing experiment that should turn one even color and stay that way. Instead, rings of blue spread out, fade, and come back for as long as the chemicals keep reacting.
When Boris Belousov sent this to a journal, the editors turned it down as impossible. The physics they had in mind was written for things settling down. Not flow-dependent structures like chemical reactions.
Are viruses alive?
Are viruses alive? Outside a cell, a virus is just genes in a protein shell with no energy running through it, so it can't make anything or copy itself. The French microbiologist Patrick Forterre argues it comes alive inside the cell it takes over, which he calls a virocell, and biologists still disagree.
How did life begin on Earth?
How did life begin on Earth? Nobody was there to watch, but microbes seem to have been building reefs in what's now Western Australia by about three point four billion years ago. How it started is still an open question, so think back to the dish.
Dr. Bob took this one rule to its logical conclusion. Energy flowing through chemicals in an early ocean organized them, and some of those mixes got good enough to copy themselves. In his view, that was the start of life.
In 2009, two chemists at Scripps in California made a pair of RNA molecules that build each other in a test tube, and when different versions competed, new combinations took over.
So to me, life is energy flowing through chemistry that has learned to copy itself, and you're one of those patterns. The whole film is on my site, linked below, where you can heat the dish yourself, and next, how your body heals itself.
What the studies show
Every claim in this answer, the study behind it, who was studied, and who paid for the research. “None listed” means the paper names no funder.
