Star Trek: Science Today

An occasional e-zine by Robert Muratore

"It's life, Jim, but not as we know it..."

In May 1987, The Firm had a hit single called "Star Trekkin'" in which an ersatz Spock utters the words making up the title of this column. How could we recognize life if it's not as we know it? Not the producer's popular humanoids with a remarkable ability to speak fluent English, but the tough cases? In order to recognize something as alive, it must be a little bit like that which we already know to be alive. From what we know of living things, the more generally (abstractly or theoretically) we can define life, the easier it will be to recognize in novel forms.

So here it is: how to define life from a theoretical point of view - based in part on a course I taught at Cold Spring Harbor Laboratory, Summer 1995.


  1. Why is the definition of life important in Star Trek?
  2. Why is the definition of life important today?
  3. A method that would appeal to Spock
  4. The three axioms of life
  5. An encounter with aliens
  6. For further reading

1. Why is the definition of life important in Star Trek?

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Within the world of Star Trek, there are at least these two broad reasons to define life:

Series Rationale
The stated mission is to seek out new, there must be some means of recognizing this life when it is found.
Plot Device
Typical Star Trek plot:
  1. crisis
  2. "it's ... alive!"
  3. back to the holodeck for drinks
The recognition that something is alive plays an occasional but crucial role in Star Trek. The characters sometimes are ensnared by or released from a crisis by recognizing that some "phenomenon" is actually a living creature. For example, in "The Quality of Life" (ST:TNG episode 235; see ST program guide), Mr. Data defies orders and risks his Captain's life because he is convinced that the "exocomp" machines are alive.

2. Why is the definition of life important today?

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I will not be addressing big issues such as the meaning of life, or the nature of human intelligence. But within this snug philosophical boundary, I will describe how we come to look at sand on a planet such as Earth (or Ceti Alpha V) and say "not alive", and look at little things burrowing in the sand and say "alive".

If we understand this, then when new complex phenomena are encountered, we will be in a position to decide whether they are living.

The opportunity to make this decision will present itself frequently with:

3. A method that would appeal to Spock

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There is a progression of abstracted beings on Star Trek who embody the ideals of logic:

The task of analyzing a phenomenon and judging whether it is alive often falls to them, so I will define life in a way that would very much appeal to them. (Two asides: (1) whether they themselves are living is a question to which I will return; (2) Troi uses her intuition to make the call; as wonderful and important as intuition is, all I can say about it here is that scientists relying solely on their intuition would end up at Gary Larsonesque meetings: "It's alive" "No it's not" "Yes it is" "No it's not!" ducking the rotten vegetables flying about).

One can judge a new phenomenon, whatever its nature, by comparing it to previous experiences. If these experiences are well understood, then the new experience can often be quickly analyzed. The scientific-technology enterprise proceeds largely in this manner (and less by force of rotten vegetables).

To apply this to the most basic biology, we would distill our sense of what makes various living things alive into a short list of essentials, and then test a newly discovered phenomenon against this list. The essentials are called rules or axioms.

The rules can be based on a widely varying set of ideas, from very specific to very abstract. Carl Sagan, in The Cosmic Connection, describes this spectrum of ideas as a spectrum of chauvinisms, each of which can be imagined to be broken.

vital force chauvinism
there is a peculiar force or energy in the universe that animates matter. There were many lively debates about this a century ago. But the harder scientists looked, all the way down to viruses and DNA and RNA, the more they found just mechanism and no life isolate. A definitive source for these ruminations is Erwin Schrödinger in What is Life? A definitive nit in the ST universe is the Genesis Project terraforming device stolen by Khan in ST II: The Wrath of Khan. I suppose that there could be a powerful terraforming device/weapon, but it should be looked at more as a plow and fertilizer thing than a source of intrinsic seeds. Sorry Spock, you'll have to find it within yourself or your religion to resurrect. Maybe the sequel should have been called ST III: The Search for Animus.
solar chauvinism
the energy for life comes from the sun or from a similar stellar source. Some spectacular discoveries of ocean-vent-based life have recently shattered this one.
organic (carbon) chauvinism
certain cellular metabolic processes are seen as necessary for life. These involve carbon-based (organic) chemistry. This was the basis for the Mars Viking tests. Certain chemical tests searched for telltale metabolic products. But silicon also forms complex molecules. (ST examples: the Horta of "Devil in the Dark" and the microbrain of "Home Soil".)
electromagnetic chauvinism
life is seen as based on chemistry (that is, the electromagnetic force). There are four fundamental forces of nature:
energy-matter chauvinism
life is seen as embodied by energy or matter.
complex systems chauvinism
life is seen as certain patterns in complex systems, whatever the systems are made of. Pattern means repetition, and repetition means cycles. These cycles are not always true, insofar as there is not always exact repetition. Chaos generalizes the idea without really trashing it because we can talk of almost repetitive events. Not only does cyclical or near-cyclical behavior appear to be a strong component of living systems, but it is thought that repetition is required for perception as well. Given all of this, can you conceive of a system showing no repetition or near-repetition in time that could be considered living? Would it then make sense to communicate with such creatures through the "natural" wavelength 21cm when the concept of frequency is not part of their being?

I find it difficult to break this chauvinism with its ideas of change and cycles and still say something more interesting than "everything is alive in its own way". If you have any ideas along this line, please write to me, and I will post your ruminations.

4. The three axioms of life

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The abstraction of life is central to the discussion of theoretical biology, much of which is carried on in the Web in a spirited manner (an artificial life site is a good starting place). Among the more popular definitions of life is a set of three abstract axioms:

  1. a living system tends to form ordered patterns
  2. among the patterns produced by a living system are copies of itself
  3. the reproductive process is subject to randomness

Axiom 1. a living system tends to form ordered patterns

Living systems, in creating pattern or structure, produce order from disorder. For example, a baby in growing produces organized bones and flesh from uniform white milk.

The production of order requires a metabolism, or use of energy of some sort. Metabolic wastes are a telltale sign of life.

The structures that are produced must be stubborn. That is, the momentary swirl pattern in coffee with milk stirred in is not a sign that the coffee is living. One means of understanding the stubbornness is R. B. Fuller's "rope trick". Imagine a long rope put together from various pieces: a cotton length connected to a hemp length connected to a polypropylene length etc. Tie a loose knot near one end of the rope. Move the rope through the knot. At one time or another, the substance forming the rope will be cotton or hemp or polypropylene. Thus, the structure (the knot) is more stubborn than the substrate (the rope material). Another example: growing muscle depends more upon what exercises I perform and less upon what cereal I eat.

I tuck my rope into my backpack, and decide to exercise by hiking in a quarry. I notice some shale, and in it see little spiral patterns. I immediately sense that I am looking at a fossil because of the intricacy of the structure, a structure that is stubborn, and has outlasted its original material to be replaced by stone.

Axiom 2. among the patterns produced by a living system are copies of itself

Axiom 2 is about reproduction. For many creatures, this means sex.

Furthermore, the system must reproduce reproducible copies of itself. That is, the offspring, as copies of parents, must be of high enough resolution to include the reproductive apparatus.

This axiom, like the others, focuses on the system rather than the individual. Therefore, it is untroubled when confronted with a mule, the sterile offspring of a donkey and a horse (and the protagonist of Isaac Asimov's Foundation).

Axiom 3. the reproductive process is subject to randomness

Here are some sweeping issues. The third axiom means that living things "don't always breed true". The randomness in the reproductive processes opens the door to selection based upon environmental factors. This allows evolution to proceed.

New computer experiments reveal that a system without parasites evolves slowly, and a system with parasites evolves hundreds of times more quickly. (You can download many of these.)

In the sense that evolution is faster in species that reproduce more rapidly, "evolution loves death more than it loves you or me" (Annie Dillard, Pilgrim at Tinker Creek, NY: Harper's Magazine Press, 1974, p. 176).

So, axiom 3, beloved by some biologists as the most important of the three axioms, is all about randomness, parasites and death.

Hollywood (Hollywood ??)

To recap, an attempt can be made to define life with three axioms. A living system exhibits:

  1. production
  2. reproduction
  3. evolution
(power, sex, death: the very stuff of Hollywood movies).

5. An encounter with aliens

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Preparing the tools

The point of assembling the axioms is to guide the construction of a set of "tools" with which to decide whether or not an observed system is living. The sort of tools to be constructed are:

a list of what to measure
known metabolic products such as heat and carbon dioxide; anything else you can (Neelix in "Phage": "unusual readings ... traces of organic energy ... looks like a bioelectric signature ... I think there's something alive in here ...")
a plan for how to make those measurements
look for known metabolic products; then general scans; the most important thing to watch for closely is when the thing gets jostled. If it's stubborn, it will tend to resist changes.
sensors with which to take those measurements
everything you've got, including those little medical tricorder doodads
a means to analyze the measurements
make graphical plots of the various properties

Applying the tools

time scales and other practical matters

Success of the application will depend on the relative scales of both time and space between the observed lifeform and the observing lifeform. In fact, the problem with axioms 2 and 3 is that many individuals take longer to reproduce than a simple scan of the sensor array would voyeuristically reveal. How can Spock make his pronouncement? He must rely on axiom 1, leaving his pronouncement as a hypothesis to be tested later by the observation of axioms 2 and 3.

life as we DO know it

As expected, the axiomatic method correctly declares that life as we do know it is alive.


Crystals form an interesting case. First, the formation of a crystal is clearly the formation of a structure. Second, a crystal reproduces: it grows, the pattern is reproduced, small pieces branch off, and pieces can break away to serve as nucleating sites for new crystals. Third, randomness yields irregularities in the crystal, which can be manifested in a Darwinian way by their greater or lesser ability to accrete new ions. So we even have natural selection of a sort. So are crystals alive? The correct interpretation of axiom 1 shows that although structures are produced, the structures are not robust in the sense that they can respond to external stresses. Furthermore, the crystals are not FORMING pattern, they ARE pattern. There is no mechanism that must fight against the tide of the universe to carve out a niche.

You might say that this is so much hand waving, and you are right. Crystals are ambiguous when looked at axiomatically. In fact, this very ambiguity is the reason that science fiction often introduces "crystal entities".


The axioms also work for viruses. However, as with crystals, viruses do not contain the mechanism for forming order; rather, they contain instructions that cause other creatures to form order for them. Viruses can also crystallize. Once, when the chauvinism of life force hadn't yet been broken, it was debated hotly whether viruses are living. Although it seems that almost everyone now accepts them has living, the debate still smolders.

Data and other androids

Various androids have appeared in the Star Trek universe, and in many instances they were accepted as alive, or the plot hinged on whether they were alive. Mr. Data can use our rule-based process to determine that he himself is alive. He creates order and pattern around him as well as any human. He can also reroute certain circuits inside of himself as a form of healing. So he fulfills axiom 1. In "Offspring", he reproduces, fulfilling axiom 2. And since his daughter Lal differs from him, he fulfills axiom 3 as well.

The Holographic Doctors

Although the missing name of Voyager's holographic Doctor recalls Dr. Who, the debate over the living state of holograms goes back to Dr. Moriarity in "Ships in Bottles". And although Janeway often forgets the Doctor while preserving the lives of her crew, Picard came to accept the living state of Moriarity. Picard's determination hinged mostly on the persistence of the hologram during the program shutdown, and the growth in knowledge and sophistication of the hologram during that period. That is, he relied upon axiom 1. Does Moriarity reproduce? If you can describe how his female companion came to be, write to me.

"Life, the Universe and Everything"

Suppose that the Universe itself were alive after a fashion, spawning little baby Universes in the form of black holes. What would evolution amount to? Watch out for Lee Smolin who is tackling these ideas.

Try it yourself!

6. For further reading

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copyright © 1996 Robert Muratore