If all people on Earth could converge towards one set point would
their combined mass have any noticeable gravitational effect on the
Earth and moon?

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Request for Question Clarification by mvguy-ga on 17 Nov 2006 08:45 PST

What do you mean by "noticeable"?

I would say it is insignificent. The reason why i say this is I assume
if you calculate the mass of all humans on earth it would still work
out less than the mass of a medium sized mountain. and as there are
many medium size mountains which have no noticeable effect /impact on
the gravitational field between Earth and Moon neither would the mass
of all humans have any noticeable effect either.

As an interesting sideline though ,I once read that a doctor
delivering a baby would have a stronger gravitational pull on the baby
than the planet Mars even when it is at its closest point. (Arguement
to refute astrology)

regards

Mongolia

Let?s consider a small, spherical planet with about the same mass &
mass-density as that cumulatively for all the people on Earth. The
population, last I heard, is at about 7 x 10^9. The average human body
has a mass of about 70 kg, with a volume of about 68 L. That?s a
volume of 4.76 x 10^11 cubic liters, with a spherical radius of 
484.34 meters. (Yes indeed, all the people now alive can be stuffed
into a sphere less than a mile in diameter.) This sphere has a total
mass of 4.9 x 10^11 kg.

   This sphere?s total mass is only about 1/10,000,000,000th that of
Earth, and the surface gravity is about 1/70,000th that of Earth at
sea level. So the gravitic effects of congregating Earth?s population
will be negligible.

I hope that answers the question without the need for a practical experiment.

Cramming the people all in a sphere is unrealistic.  I expect that
they would need to be stacked in rows, alternating layers at right
angle.  If this were done neatly  - requiring a good deal of
cooperation -  they could probably be stacked in a steeply sloping
pyramid.  Qed100 could calculate the dimensions of the base necessary
to have the volume of his sphere.  Actually, he could allow for a
little less volume, since as the stacking progressed, there would be
some ... uh ... "compacting" ...

I think I dropped a few zeros earlier. That should be approximately
1/10,000,000,000,000th.

Hi Myo

Would also advise they all take a shower before agreeing to your
stacking arrangement

Mongo

Mongolia,

The "invitation" to the experiment will promise to reimburse round
trip fare and participation in various extremely generous lotteries
for those who volunteer to start the pyramid, many billions for those
in the first few layers, lesser billions for the next group and so on.
 That should get the thing started, but with respect for the blondes
who volunteer to be first, your suggestion is good  - and and may help
organize things.  Those who can demonstrate (how?) that they have had
a shower in the last 24 hours, will form a group that is allowed to
climb up and form the top layers.

I think the experiment should be sited in central Australia, an old
and very stable region that will allow better measurement of the
effect  (maybe the period of the moon also needs to be considered).

Naturally, the people who monitor the seismographs, etc., will be last
to join the pile  - which could cause a crush at geo-science schools
when the experiment is announced.

Myo

As far as stacking is concerned, I prefer the BK Double Stacker. The
bacon melts my cares away...

No,I thick, since human bodies are so lighter than the earth.



Liou

No,I think, since human bodies are so lighter than the earth.



Liou

Absolutely no effect on anything.

Actually some thing to that effect happens in India during Maha Kumbh
Mela every 12 years when there will be 50 million people concentrated
in one small area.

No effect on anything.


We can model this effect like this.
The present pouplation of earth is 6.2 billion. Let us assume an
average weight of  70 kg per person. The total mass will be 4.24e11
(Scientific notation).
The mass of the earth is 6e24 which is 15,000,000,000,000 (15 trillion
times the mass of all people put together). Obvioulsy all the people
cannot be concentrated into one point. Let us assume each one needs
one square mt of place to stand on.
Then the total area occupied is 6.2 billion sq mts=6200 sq kms (area
of about belgium or netherlands). The addition of density will be 70kg
per cubic m which is way less than 3500 kg per cubic m which is the
density of the surface of the earth.
So what we are talking about is an insignificant mass spread over some
area and its gravitational force on moon is 2.182e-16 Newtons which
cannot even lift one bacterium or a dust particle. Forget about any
effect on Moon or the earth