Tagged with Science

Are Stars Alive?

The other day over lunch we half-jokingly talked about whether or not stars are alive. A colloquialism among astronomers is that a star is "dead" when there is no more nuclear fusion, so stars in the late stages of their evolution are "dying". Some smartass took the metaphor literally and pointed out that stars are always dead, never alive. But are they, really? they asked in return.

Now, the gut reaction is, of course, that stars are not alive. They are described quite well by physics alone, with a little bit of inorganic chemistry. But one should always question one's own intuitions and stars after all do have metabolism, a life-cycle and are "born" in generations. They do not reproduce directly, but by enriching the interstellar medium with they fusion products, thereby influencing the next generation of stars. Stretching the analogy, one could say that stars that fail in doing this (for example stars that collapse into a black hole without supernova explosion) have "failed to reproduce" in an evolutionary sense.

At the time I could not quite articulate why it still felt wrong to me to call stars alive, and I did not want to argue by some outdated list of strict criteria, vaguely remembering that the definition of life does not have such a clear-cut answer as one would like.

Luckily one the podcats I listen to just answered it for me: Sean Carroll interviewing Sara Imari Walker on Information and the Origin of Life .

They don't talk about stars, but connecting life to information processing was what had slipped my mind over lunch that day. I will not reiterate it here but highly recommend to listen for yourself, or read the transcript on that same page.

A highlight for me was this section:

There is something about intelligence as a physical process that’s quite different. If you just had physics and chemistry and no biology, no organisms, no evolutionary history acquiring info§rmation, you would never see a planet launching satellites into space.

What’s interesting to me is what can happen causally in the Universe. And I think there’s a lot of processes that can happen, but just don’t. And that what biology does is it somehow can cause things to happen that wouldn’t happen outside of the kind of process that biology is. And so, I think there is a deep connection actually between information and causation.

(Slightly edited and condensed by me.)

Another take-away message is that "life" or "no life" is not necessarily a binary decision, but a continuum. Things can be less alive than others. I think this maps nicely onto consciousness. It's not that there is some moment when "the lights turn on" but a scale with some beings haveing more of it than others.

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Computation Outside The Nervous System

This presentation is quite mind-blowing. The full title is What Bodies Think About: Bioelectric Computation Outside the Nervous System and it shows almost incredible results of what happens when you influence the communication between cells, notably not neurons. Limb regeneration, double-headed worms, memory remaining after the brain was cut off!

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On Consciousness

The other day I listened to Sean Carroll talking to David Chalmers about consciousness, among other related things. I won't summarize it here, go listen for yourself or read the transcript.

What I will do is shortly write down where I stand on some of these questions. Not because I think I have anything new to say, but to clarify it for myself and have a reference to see if I change my mind in the future.

Is there a "hard problem" of consciousness? I am not totally convinced. Maybe subjective experience is just what it feels like to have a brain that continuously hallucinates and updates a model of its body and the world around it. (Which reminds me that I should read more by Anil Seth.) I don't think this justifies calling consciousness an "illusion" though.

Dualism? No. Even if "property dualism" might not directly contradict the physical world, I find it much more of a stretch to assume some new fundamental property of matter than to just admit that we don't yet understand how matter makes minds.

Emergence. I am ambiguous about that term. Yes, it can be abused as a handwavy "magical" process that explains nothing. But it makes sense to have models of the world that work att different levels of description, as longs as the higher-level ones can, in principle, be reduced to and understood in terms of the more fundametal models.

Are philosophical zombies conceivable? I don't think so. An entity cannot behave the same way as a conscious being without a sophisticated mental model of itself and the world, and if subjective experience comes along with these, then there are no zombies.

Do we live in a simulation? Probably, but this makes surprisingly litte difference. Randomness in quantum mechanics and a finite observable universe? Very convenient ways to save calculation effort. Still, we want to understand as much as possible of how it all works and since the rules seem to be consistent throughout, without the gods intervening, it does not matter at all for every-day life, how the universe came about. Which is not to deny that the answer to this is ultimately interesting.

Addendum, 2018-12-14: By coincindence it turned out that, when I after a few months pause took up listening to Eliezer Yudkowsky's From AI to Zombies again, I had left it right at the beginning of the zombies chapter. Now that I am through it and its follow-ups, I cannot do much more than agree with Eliezer, since I found the reasoning convincing and couldn't have said it anywhere close to equally well.

In summary: While one might find the philosophical zombies conceivable, they are not in fact logically possible.

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