Re: [Algorithms] rather curious

[Jeff L. <je...@di...>]

The reason people don't know a lot about relativistic physics is they have trouble with Galileo let alone Einstein.

Funny this should come up today since last night we got into a little debate about this at dinner with some friends.  My friend works at JPL and we were talking about skydiving and this came up.  No one believed us that the objects hit at basically the same time regardless of mass.  So we all started dropping stuff on the table to prove it.  Pretty funny.  It is always amazing how a simple "try it yourself" can surprise people.  In general they just believe it should be some way and never check it out.  No wonder Galileo ended up in jail.

The whole what is gravity thing is pretty tough.  Claiming to have the "right" answer is probably folly.  Clearly Galileo/Newton works fine for most applications any human would run into.  I am no expert on gravitational physics but from what I know, common thinking is based  on  Einstein's theory of General relativity.  The mass of objects warp spacetime and the falling is explained by objects following a straight path in space-time. 

Galileo went to great pains to prove that Aristotle and Plato were wrong about falling objects.  If he wasn't exactly right to the order of 10^-24 or whatever, I am not sure it matters.  At JPL, good old Newton does the job for most things.

Using Newton's equations for the force of gravity and f=ma you can see how the mass of the falling object just drops out.  Different masses do cause the objects to hit with different forces but that is different from the time, eh.

If someone wants to implement actual relativistic physics for simple rigid body simulations, I am sure it would be cool, but Newton is good enough for me :)

Didn't they do the feather and rock demo on an Apollo mission as a pr thing?  I seem to remember seeing a video of it.

-Jeff

At 04:26 PM 9/10/2000 -0500, you wrote:
>hey,
>i am just wondering, but how many people know about *this*
>"gravity isn't really a force" and that it is caused by the curvature in the
>space time fabric.
>
>And, if you drop two objects in a vacuum they *really* don't fall
>at the same rate (difference is very small, order of 10^-24) <this *makes
>sense*>
>why don't more people know this?
>
>even if it's at a difference 10^-24,
>i assure you, if we had money that was this accurate, banks would "require"
>this much precision in there software :|
>
>i am just curious what is the *the few on this list*  knowledge about
>this...
>
>i recently (3 minutes ago) got in an argument with a friend on this *topic*,
>he told me his professor said that "Gravity is a FORCE" and saying anything
>different from that is pure anarchy.
>
>i told him what is above is true and André Lamothe writes this in all of his
>books, and i'm pretty sure he knows more than your professor (the laws make
>sense as well), ...
>
>
>
>i am probably just t-ed of cause i didn't have more proof about the space
>time fabric one :|
>
>
>btw, andre, if your not on the list;
>i highly suggest you join :) i know your busy with volume 2 and all...
>
>peace,
>akbar A.
>
>
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