*What is "Life"?

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Life is/are many ways of mortality management.

I would go to that definition of life or who is alive, biologically speaking, perhaps the simplest and vaguest way, that every piece of mass that is composed by cells is alive, as only living organisms are made of cells, cell being defined as the basic unit of all living organisms.

All living things have purpose: To consume, to grow, to reproduce, and to die.

And if you're a Fellini fan, then this includes dying alone, naked and penniless, in the midnight rain, while people all around you sleep warm, well-fed, and comfortable in their beds.

Interesting that despite a year of college physics and more than a year of college chemistry, radioactivity and nuclear reactions only came up in the chemistry classes:
The Chemical World: Concepts and Applications by Kotz, Joesten, Wood, and Moore, 1994, Harcourt Brace & Company, Orlando.
Chapter 19: Nuclear Chemistry
Section 19.2: Nuclear Reactions
Section 19.6: Nuclear Fission
Section 19.7: Nuclear Fusion

Physics for Scientists and Engineers, 5th ed., by Serway and Beichner, also includes a section on Nuclear reactions. So you are right that fusion can be considered within the domain of physics, but wrong that it is not also chemistry.

In any case, stars are not alive.


Wrt viruses vs. humans and any other heterotrophs, we are capable of reproducing our own genetic material using enzymes manufactured within our own cells; viruses are not capable of this. It's not a matter of where the energy comes from; it's a matter of where the DNA (or, theoretically, other genetic material) comes from.

Everything is physics, but not everything is chemistry.

Yet we talk of the birth of stars.. their life-time.. and their death.. and they even give birth to cute little planets...

So what do we mean by this.. ?

For the time being I'm sitting on the fence.. until we get some clear-cut definitions.. on what life is considered to be.

When I get more time I will take a look myself.

It's a good question though.

Is there no authoritive answer available.. ?

Or is it all down to philosophical opinion.. ?

Someone must know.

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"A star is not a homogeneous blob of hot gas. It is an organized structure of discernable components arranged and interacting with one another in definite ways. The sun, as a typical example, comprises, anatomically, an inner core within which nucleosynthesis occurs, a radiative layer that carries energy out from the core by radiation, and a convective layer that carries the energy further by convection. This onionlike structure continues outward from the core to the periphery with the photosphere, the chromosphere, and, at the outer fringes, the diffuse corona."

http://www.starlarvae.org/Star_Larvae_T ... anism.html

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LKL, in order to Fully understand Nuclear reactions you'll need at least 2 years of college physics which shoudl include classical mechanics(langrangian and hamiltonian as well), electrodynamics, and quantum mechanics(including quantum field theory). You need to know some quantum field theory in order to get a solid grip on Nuclear Physics where nuclear reactions and radioactivity are studied IN DEPTH.

while nuclear reactions are also studied in physics, that doesn't mean that nuclear reactions aren't chemistry.

wrt stars and planets, we speak of 'stellar evolution' and stars 'birth' and 'death' as metaphors. We also may say that our cars are born and die, and that car design 'evolves,' but that doesn't mean that the cars are alive, either.

Comparing Stars and Cars is a BAD analogy LKL. What is YOUR definition of life BTW? We say a car dies when the engine becomes so worn down that its moving parts cease to work. In which case the engine can be replaced, unlike a star which CANNOT be reignited once its *fuel* is consumed that stellar fusion ceases. The term "Nuclear Chemistry" is somewhat of a metaphor, because nuclear reactions require knowledge of quantum physics to understand whereas classical chemistry does NOT require quantum physics to understand and to predict.

FWIW, I was comparing the use of the word 'death' as a metaphor in English discussions of stars and cars, not comparing the objects themselves. In both cases, we have no english term specific to the type of functional cessation that each (inanimate) object goes through, and so we use the word 'death' as the best approximation.

And, actually, I rather like your definition on the first page:

Stars are disqualified in that they do not reproduce themselves (no genetic material determining the nature of future stars) and they produce, rather than consume, energy.

This is true. Physics is the most fundemental of the sciences, followed by chemistry, followed by biology.

If you're really interested in fundamentals, shouldn't you start with mathematics?

Math's not a science.

'BS' is the most fundamental thing. Remember:

GOD is applied POWER
which is applied GOVERNMENT
which is applied POLITICS
which is applied ADVERTISING
which is applied SOCIOLOGY
which is applied PSYCHOLOGY
which is applied BIOLOGY
which is applied CHEMISTRY
which is applied PHYSICS
which is applied MATH
which is applied PHILOSOPHY
which is applied BS

A rather long list of equivalents which boils down to God is BS. I'll go along with that.

The nuclear reactions that take place inside of stars in fact do have a lot of parallels with the metabolic reactions that occur within living organisms. Yes stars do release energy, but so do living things . It was mentioned earlier that stars DO have an internal structure, albeit simpler than living cells here on earth and that structure is MAINTAINED by the energy releasing process of thermonuclear fusion. When a star dies, the nuclear reactions that sustain it cease and its internal structure disapates-NOT unlike when a living organism dies. So with stars, death is an analogy whereas with cars its just a metaphor.
The only thing that stars do not do is pass on information to new stars formed from their embers. So I say that are quasi-living but not quite Life as we think of it.