How far back does evolution go? Is it the time the first cells were created? Or does it go even further back?
The first living thing would have to be a self-replicating molecule that uses energy. Different forms of this self-replicating molecule would have different reproductive success.
There is a not-unpopular theory that the original form of life on earth was an RNA molecule. RNA is a special molecule, because it can both act as a store of data, and as an enzyme for catalyzing reactions. According to this theory, specialized data storage in the form of DNA evolved later, along with specialized enzymes.
Here's a brief overview of the theory that shows how evolution could happen with chains of RNA only: https://www.youtube.com/watch?v=K1xnYFCZ9Yg
Jack Szostak at Harvard has a great series of videos explaining this theory, and also a number of experiments that he and his students have performed. https://www.youtube.com/watch?v=MPzWrv6l9l0
Evolution can be defined as a gradual development of some thing. This thing does not necessarily have to be defined as life. Since celestial formations develop from a starting state then yeah, they can be considered evolution.
In the context of the conversation as it pertains to life, I would imagine that a discussion of evolutionary life would start at the moment a given thing becomes capable of change as it replicates.
A part of the definition of living things is that they reproduce. That reproduction (with variation) is a necessary precursor to evolution. Stars and planets do not reproduce themselves, so they cannot be said to undergo selective evolution.
Kind of :).
We don't really have a definition for life.
Imagine an alien ship landed, and out popped these things. They said 'hey what's up' in their language. Cool. And as it turned out - they don't 'die' by natural causes, or reproduce. The pop out of some chemical process. It's a little creative, but physically plausible.
We could build 'mechanical wombs' fecundated with ovaries and sperm we farm. Is that reproduction? What if we are able to synthesize sperm and ovaries form scratch? 'Reproduction'? Depends on how you look at it I suppose :)
As the Scientist stated in the article, there really isn't a hard boundary between the living and non-living, because when you reduce our definitions down the level of physics, there is no distinction, at least materialist terms.
'Life' is something we observe, and give a name to, but because of the underlying assumption of materialist science (that the Universe is matter/energy bouncing around randomly) - it really doesn't have any real objectivity. You (or we, collectively) just define it to be what you (we) want it to be and that's it.
For instance, crystals reproduce themselves, but we do not consider them living. So we decide that livings things use energy, which rules out crystals as being alive.
Fire reproduces itself, and it uses energy, but we don't consider it to be living, so we say that living systems preserve information http://scienceline.ucsb.edu/getkey.php?key=360 .
Viruses reproduce themselves-- in fact, using the same information-containing molecules that living cells do, DNA and RNA, but they do not use energy (instead they hijack the metabolic machinery of living cells). So we do not consider viruses alive.
So in various definitions of life, you will find criteria such as "uses energy" (has a metabolic process) and "transmits information" (in the form of DNA).
That we have defined such criteria does not mean we arbitrarily made up such distinctions. Human beings differentiated between mechanical and electromagnetic energy, or had the concept of "species", long before we had strict scientific definitions of these things. It is the same with living and non-living phenomena. The only difference is that we arrived at a chemo-physical definition of living much later than other phenomena.
Saying that life is not objectively real is nonsense. That's like saying there's no objective distinction between mechanical and radioactive energy. They're objectively different phenomena, in theory and in measurement. The ultimate conclusion of this line of reasoning is that any distinction between any thing or phenomenon is not objectively real, just a fancy of the mind (which you will find agreement on with Hindu and certain Buddhist philosophers).
Or perhaps you are actually claiming that rocks are alive? Or there really are no differences between a rock and a lichen? If there is no objective, "real" difference between living and non-living things, then a quartz crystal is actually alive (and perhaps conscious) like new-agers claim?
In the case of your aliens, I would argue they are intelligent, but not alive-- sort of like a robot or AI machine. Those aliens are like a side effect of that chemical process. (Unless they in turn re-created the chemical situation that they originate from-- but then of course, they would be reproducing, and thus, living things).
Your aliens aren't that different from if we sent drone robots that we created to aliens. Those drone robots aren't living, though they may be intelligent, and interact intelligently with the aliens. But they don't reproduce; they are a side effect of another living chemical process-- namely, human beings. Unless, of course, those drone robots managed to re-create themselves, or created humans which in turn replicated drone robots.
In the mechanical wombs thought experiment, we are still alive, because we are reproducing. Your mechanical womb is basically an artificial egg. A chicken is just an egg's way of making another egg, after all.
Would you consider a test-tube baby not to be alive?
A multicellular organism is epiphenomical of the cell, and the cell is epiphenomenal of the replicating DNA molecule. Life doesn't start with complex, conscious multicellular organisms like ourselves; it starts with simple, replicating molecules-- namely, DNA.
"That's like saying there's no objective distinction between mechanical and radioactive energy. They're objectively different phenomena, in theory and in measurement."
Of course they are different material phenom - but I''m indicating that in materialism - you have the problem of only being able to define what life is, in very materialist terms - which will always fail.
So you say: "Life is these properties". Fine.
Now you can go out and measure things.
Some things are 'life' , some are 'not life'.
According to your definition.
But however you chose to define it, materially, it falls apart very quickly.
"In the case of your aliens, I would argue they are intelligent, but not alive-- sort of like a robot or AI machine."
I don't agree with this. How can you say this alien that appears in every way to be intelligent, creative, conscientious, self-aware - 'conscious' - is not 'alive'.
Let me ask you - are you 'conscious'?
Prove it to me!
--> You can't <--
By empirical, objective, materialist measure you are a biological machine - a material process - that's it.
You can say: "I reproduce therefore I'm alive"
The alien says: "I'm as alive as you are, and reproduction has absolutely nothing to do with it"
Or rather: The alien is by all accounts and every reasonable observation - 'alive'- it just doesn't fit into another, narrow mechanical view of what life is.
He makes a pretty good case.
So - however you chose to define life 'materially' - anyone can likely quickly come up with a situation in which you have the appearance of 'consciousness/life' that breaks those rules.
It's because we're trying to define it the wrong way, using a set of rules that won't permit it.
Another hint:
The definition of 'life' that you've just offered is not cannon.
So how is it possible in 2016 that we don't have an obvious, simple, and objective definition of 'life'? How could we possibly even debating this?
... because materialism (i.e. the assumption that the Universe is a big mess of particles interacting randomly according to set of rules) - does not allow for it.
You may chose to identify certain 'patterns' as 'life' - but your choice of what constitutes life is completely arbitrary.
"Saying that life is not objectively real is nonsense. "
Really, this is false. It's only 'real' if you arbitrarily define a set of processes to be 'life'.
You'd basically be defining 'life' as just a set of mechanical properties - that is really insufficient for describing what we all observe in 'life' - which is to say something transcendent.
Trying to define life in material terms is actually, kind of 'ridiculous'. We like to try it, because it's the only way we know how to be objective.
But - I'd argue that 'life' is the expression of something - not the existence of material components.
And I'm not making this argument out of opinion - it's rooted in what any normal person would consider to be 'alive' vs. 'not alive'.
"That which is expressed" - not the mechanical details of that expression.
Biology (and physics) is ultimately a useful tool for some things, but it is not ultimately going to help us find the answer to what 'life' is, in many ways, it will send us in the wrong direction.
Rather than saying some things are life and others non-life, I would instead say that some are living and (most) others, non-living.
Are you seriously going to claim there is no objective way to say that a fish is alive and a star isn't?
If so, I would surmise that we disagree on fundamental issues and thereby cannot have a productive discussion.
"By empirical, objective, materialist measure you are a biological machine - a material process - that's it."
Do you have empirical, objective, materialist and definitions of "biological" and "machine"? Or even "process"?
On a parallel note, deep learning neural nets rely on randomness in connectivity and order of examples, and sometimes just consumes random numbers and turn them into coherent images or sounds. Entropy/randomness is essential in Reinforcement Learning in the exploration-exploitation dilemma - we need to discover the space of possibilities, and in order to do that we need randomness. Interesting how chaos is tangent with intelligence and life, it is practically creating a space for them.
Evolution is not an entirely objective thing, really, it's the arbitrary theoretical line we draw around our observation of bags of random things bouncing around in a random environment. There is no 'process' per sey, other than somewhat arbitrary means we wish to use to describe it.
So the answer is: 'evolution goes back as far as you want it to' - depending on how you chose to define it :)
I could describe throwing a ball to you into terms of how the quantum wavefunction evolves over time to produce the end state from the start state, and it would be a perfectly fine description, but for the sorts of things we do, usually a Newtonian physics level of description will do because we're generally concerned with coarse level details, not the momenta of each individual atom involved.