RE: Adrian and I disagree on faith.
February 6, 2010 at 9:43 am
(This post was last modified: February 6, 2010 at 9:46 am by Welsh cake.)
(February 5, 2010 at 11:36 am)leo-rcc Wrote:Faith ≠ AssumptionQuote: I don't think believing that the sun will come up tomorrow is a faith based position, since you have good reason to believe so, same with having a job next month.I don't consider previous experience valid evidence for future events. It cannot foresee the future.
There is no valid reason to assume that the Earth will keep rotating so you will see the Sun again. Is is a matter of faith. No matter how many good reasons you have of believing that you are correct does not make it any less of an assumption. Just because we know the Earth has always done it, is not a guarantee that it will continue to rotate.
Is the Earth likely to continue? Yes. Is it certain to continue? No. Do we therefore assume that the Earth stops rotating? No. We assume that it does continue, we have to accept on faith that it doesn't stop.
No one has been alive long enough to witness the Sun and solar system make a full orbit round the Milky Way core, but we have the math, and therefore we can work out how long it will take.
Will the Earth contine to rotate exactly as before? No. Lunar tidal drag slows the Earth's rotation by about 0.002 seconds per day per century. Using Cassini's Laws and conservation of angular momentum, we can determine the rotation of Earth is slowing so a day gains 17 microseconds each year (if those are calculations are correct the day will become 1 second longer in 60,000 years... and one minute longer in another four million years, its all very exciting I'm sure).
Left to their own devices, tidal acceleration means the Earth and Moon will achieve a spin–orbit resonance in about 50 billion years, however in another projected 5 billion years our main sequence star* will have consumed much of its helium and become a red giant. With an estimated size increase from 0.01 astronomical unit to 2, the fate of Earth is unclear but using the Roche limit to work out the effects on tidal forces on the planet, its highly likely to be destroyed along with Mercury and Venus in the sun's outer layers.
As far as I'm concerned, faith finds itself out the window, in the gutter where it belongs.
*according to the Hertzsprung–Russell diagram.