Re: What Atheists Can't Answer

In article <hugh_gibbons-A0DBCA.23482401082007@[EMAIL PROTECTED]
>,
 Hugh Gibbons <hugh_gibbons@[EMAIL PROTECTED]
> wrote:

> In article <46B163B4.C90DACF4@[EMAIL PROTECTED]
>,
>  Rich Travsky <traRvEsky@[EMAIL PROTECTED]
> wrote:
> 
> > Hugh Gibbons wrote:
> > > 
> > > In article <46AC2920.F170A1D9@[EMAIL PROTECTED]
>,
> > >  Rich Travsky <traRvEsky@[EMAIL PROTECTED]
> wrote:
> > > 
> > > > Bye bye for everyone. The planet will be destroyed.
> > > >
> > > > RT
> > > 
> > > I see no reason to think the planet would be destroyed.
> > 
> > The will become a red gas giant whose diameter could expand as far as 
> > Earth's
> > orbit. Plus, some stars in this class can go nova.
> 
> I realize that.  Let's think a little bit about what the density of a 
> solar mass expanded to 100 million miles in diameter would be.
> 
> Ms = 2x10^30 kg.
> 
> 1 AU = R = 1.5*10^11 meters.
> 
> V = 4/3 *pi* R^3 = 1.4x10^34 m^3
> 
> That makes the AVERAGE density of the expanded sun about 0.14 g per 
> cubic meter.  The much thinner part out where the Earth is will be
> just a fraction of that.  
> 
> The Earth will be running into that very thin medium very fast, though, 
> about 15000 m/sec.  Each second, therefore, each square meter of the 
> Earth's cross section (approximately) will be decelerating 0.00014 kg of

> mass by 15000 m/sec, which delivers a 2kg-m/sec impulse to the Earth.  
> You'd feel that wind, for sure, and it would be damn hot.
> 
> Multiply that by the cross section of the Earth (1.3x10^14) and you get
> an impulse of 2.6x10^14 kg-m/sec of impulse each second.  So each 
> second, this would slow the earth down by 
> 
> 2.6x10^14 kg-m/sec / 2x10^30 kg = 1.3x10^-16 m/sec.  
> 
> In a whole year, it would slow down by 4x10^-9 m/sec.  In a billion 
> years, that'd slow us down by 4 meters per second.
> 
> When the sun shrinks into a white dwarf at the end of its stellar 
> lifetime, the Earth will still be orbiting it, with a mass and velocity 
> not much different than they are now.
> 
> Unless I made a huge math error, which is possible.

Well, it looks like I DID make a huge math error.  Each second,
a square meter of Earth's cross-section will be decelerating 15000
times as much mass as I originally computed.  That brings the 
deceleration of the earth to 4x10^-9 x 15000 = 0.00006 m/sec each year.

The expected duration of the sun's red-giant phase is on the order of 
100 million years.  The earth will lose several thousand meters per 
second of speed due to passage through the sun.
years.