Text 28638, 79 rader
Skriven 2007-05-06 06:15:00 av Jeff Binkley (1:226/600)
     Kommentar till en text av John Hull
Ärende: MUSLEMS
===============
JH> VH>>> John, imagine we're going to the newly-discovered planet some
JH> VH> 10 light
JH> VH>>> years away. At an acceleration rate of 1G, how long would it
JH> VH> take us to
JH> VH>>> get there?

JH> JH>> I haven't a clue.  Velocity is cumulative in zero G under
JH> JH>> constant acceleration, so you have to know how big the engine
JH>is, and what  VH> its thrust
JH> JH>> to figure velocity.  In any case, you would have to flip ends
JH>about  VH> halfway
JH> JH>> begin decelerating at the same rate to maintain constant
JH>gravity.  VH> Starting
JH> JH>> from lunar orbit would also lower the inertial impulse you had
JH>to  VH> overcome a
JH> JH>> the start.

JH> VH> It's easy to figure out, John.  The Earth's gravitational rate
JH> VH> of acceleration is 32.2 ft/sec/sec.  The speed of light is
JH> VH> 186,000 miles per second.  If you accelerate at 32.2 ft/sec/sec,
JH> VH> how long will it take you to reach a speed of 186,000 miles per
JH> VH> second?

JH> VH> Then applying the forumla D = 1/2 G t^2 how far would you have
JH> VH> come?

JH> VH> Remember, having reached the speed of light, you must now
JH> VH> DECELERATE to make landfall on your planet -- which will take
JH> VH> just as long as it took you to reach light speed.

JH>That's oversimplified from what I found on a couple of websites.  For
JH>example, your acceleration rate is for gravity in atmosphere, and you
JH>can never actually reach the speed of light in normal space
JH>(according to Einstein), etc.  But I still understood the intent of
JH>your question, which was to imply that we can never reach another
JH>inhabited star because the distances are too far to make it humanly
JH>possible.  As I said, I don't think that to be the case, and neither
JH>do a lot of people way smarter than me.

The acceleration force of Earth's gravity has nothing to do with 
atmosphere.  It is fixed at 9.8 m/s^s.  Gravity is based upon mass.  The 
atmosphere only limits the speed at which a falling body can reach 
before striking the Earth.  That is called terminal velocity.  

Now I once remember challenging a caste of characters as to what causes  
gravity.  I never really got an answer.


JH> JH>> There's a formula you can use to figure such things, but I
JH>don't  VH> have it.
JH> JH>> Suffice to say it would take awhile.  But, from the way you
JH>asked  VH> the questi
JH> JH>> it is obvious you assume that it will never be done because of
JH>the  VH> time fact
JH> JH>> You have no way of knowing that, or of knowing whether or not
JH>we  VH> will ever
JH> JH>> able to achieve FTL travel. There is a rather large group of
JH> VH> theoretical
JH> JH>> physicists who think it is possible to "fold space" in order to
JH>go  VH> from A to
JH> JH>> nearly instantaneously by utilizing curved space.

JH> VH> My son-in-law, who is an Aerospace engineer with NASA tells me
JH> VH> he doesn't believe we will ever reach the speed of light.
JH>Remember that most learned scientists once thought the earth was
JH>flat, and that the earth revolved around the sun. Considering where
JH>we were in physics just 100 years ago, I would not presume to assume
JH>that we know everything there is to know about quantum physics, or
JH>the behavior of light.

I think your solution of "folding space" is more likely to happen than 
breaking the speed of light.  At least until we can find a way to shield 
ourselves from the effects of reaching the speed of light.


Jeff

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