October 30, 2012

General Theory of Irrelevance, Part 1

As a philosophical, and probably temperamental, style, I have always found great comfort in theories of hopelessness.  Luckily for me, such theories abound and exist at every philosophical and existential level.

Take, for example, the theory at the outermost concentric ring of reality, the life cycle of the sun (or Sun, since it's so special to us).  The Sun is in its main sequence, as it's called, where it's busy converting its hydrogen supply to fused helium.  This generates heat which radiates to Earth, and this is the fundamental energy powering life on our planet.  The Sun, like everything else in the known universe, is subject to basic conservation and thermodynamic laws, and it can't go on forever like this because, large as it is, it's a finite mass.  Toward the end of the Sun's life, it will begin to expand as it exhausts its fuel; it doesn't have the mass to go supernova (the major leagues), but it's got enough heft to achieve red giant status, sort of the Triple A baseball of stellar transition-states.  I've always found this a fairly convincing argument (among many) against Creationism: I mean really, God put us in a galaxy where our own Sun isn't even one of the Big Boys?  That doesn't make any sense. Anyway, the Sun is about halfway through its main sequence, with about 5 billion years to go on its journey to White Dwarfism (sorry, that's just the way it goes), but before you relax and start thinking you have, well, all the time in the world, pay attention: 

Earth's ultimate fate is precarious. As a red giant, the Sun will have a maximum radius beyond the Earth's current orbit, 1 AU (1.5×1011 m), 250 times the present radius of the Sun.[108] However, by the time it is an asymptotic giant branch star, the Sun will have lost roughly 30% of its present mass due to a stellar wind, so the orbits of the planets will move outward. If it were only for this, Earth would probably be spared, but new research suggests that Earth will be swallowed by the Sun owing to tidal interactions.[108] Even if Earth should escape incineration in the Sun, still all its water will be boiled away and most of its atmosphere will escape into space. Even during its current life in the main sequence, the Sun is gradually becoming more luminous (about 10% every 1 billion years), and its surface temperature is slowly rising. The Sun used to be fainter in the past, which is possibly the reason life on Earth has only existed for about 1 billion years on land. The increase in solar temperatures is such that in about another billion years the surface of the Earth will likely become too hot for liquid water to exist, ending all terrestrial life.[108][109]

 This may provide some comfort if you haven't saved enough for retirement.  You were thinking we all had five billion years to go, but we're not going to be around to see the Sun reduced to its pitiful White Dwarf destiny.  You might call this the ultimate Inconvenient Truth. 

It's nothing to worry about, however, as I shall attempt to describe subsequently.

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