Re: Newton (was: Re: Pentode-Triode Sound)

On Mar 10, 12:18 pm, John Byrns <byr...@xxxxxxxxxxxxx> wrote:
In article <45F242DB.AC280...@xxxxxxxxxxxxxxxxxx>,
Patrick Turner <i...@xxxxxxxxxxxxxxxxxx> wrote:





John Byrns wrote:

In article <45F15FCC.FAC47...@xxxxxxxxxxxxxxxxxx>,
Patrick Turner <i...@xxxxxxxxxxxxxxxxxx> wrote:

One can only ever really be partially correct, and partially wrong.

Newton gave us laws of motion which seemed SO RIGHT.
but you could never get a rocket to visit planets of the solar system
just relying on Momentum = 1/2 m x V squared et all.
He was right within his limited views, and for our little world, Newton
was pretty right,
if all we want to do is pull a train with a locomotive.

Is this really true, that it requires more than Newtonian Physics to
send a rocket anywhere in the solar system? I don't know one way or the
other, I never thought about it and just assumed that Newton was all we
needed for this simple task, so I am curious.

To plan a space probe, relativity has to be factored into delicate
equations worked out in computers. A team of men would be far too slow
to work out the timing and directions of rocket motor thrust activations
to
get from A to B in space.
Without Einstein's ideas, a simple moon shot would be very difficult.
Newton was a fantastic mind, and the world's civilisations were
profoundly
adavnced by his science.

But after Newton there were a large number of luminaries who
gave us additional ideas about space and time, and enabled us
with mathematics and computing.

Going to the moon isn't just sitting in a rocket, lighting a fuse,
and then steering your way there, and back again.

Perhaps you should read what NASA have to say about the requirements for
interplanetary travel. I'm sure that using newtonian laws only, you'd
easily miss the moon altgether
and have no way back, and perhaps end up at Alpha Centuri in about
100,000 years, frozen solid
in the rocket that couldn't return. But space is so vast the chance of
ever turning up
at any other star or solar system planet is only 1 in 50 billion, so in
100 billion years you'd still be drifting
along frozen solid, still gazing out the port hole....

My question related to your statement that Newtonian physics wasn't
adequate for interplanetary travel within the solar system, and now even
for travel to earth's moon. I will put the question to another group
that may be able to direct me to the answer with respect to navigating
to the moon and back.

I did not raise any questions one way or the other about the need for
computers to implement the navigation equations, be they Newtonian or
relativistic.

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/- Hide quoted text -

- Show quoted text -

John:

To the moon and back using rocketry and gravity slingshot power is
simple (OK, not so simple) ballistics. The speeds do not begin to
approach relativistic levels. Jules Verne calculated it pretty
accurately-by-implication in his short novel, and the only thing wrong
with his "physics" is that had his projectile actually approached
escape-velocity + allowances for atmospheric friction, his passengers
would have been a thin smear on its base even with their water
cushion. That was well over 100 years ago, long before relativity was
even a gleam in anyone's eye. I believe he even had escape velocity
nailed as well. It has been years since I last read it, but there was
a table similar to this:

http://www.astronautix.com/lvs/julongun.htm

At the end of it.

Within the solar system it is a little more complicated and requires
in-flight corrections, but it is still just ballistics. Get to a
significant percentage of light-speed and you will finally require a
higher level of physics... maybe. Much of it depends on where you are
and where you are going and how close you are to large gravity
anomalies such as black holes.

Peter Wieck
Wyncote, PA

.

Relevant Pages

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