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I have these questions related to my question title:

  1. Do we, other species and things have our own gravity?

  2. How much Gs a human have?

  3. Are we effecting Earth, nearby moons and planets with our gravity?

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Are we increasing the gravity of Earth with our population

No, we don't increase the total mass of the Earth, because our bodies are made of things that were already on Earth (food, water, air, minerals etc).

Do we, other species and things have our own gravity?

Yes everything with mass has gravity (and things without but that's complicated)

How much Gs a human have?

Not quite the right question. The total mass of humans is probably around 300 million tons (7billion people * 40kg per person). The earth is about a billion, billion times heavier than this so we don't add very much.

Are we effecting Earth, nearby moons and planets with our gravity?

Yes, you attract the Earth in the same way that the Earth attracts you - but the Earth is a lot bigger than the mass of all the people so you don't have much effect.

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Life on the Earth only increases the mass of the Earth and hence the gravity that the Earth produces to the extent that the life (plants in particular) absorb the Sun's energy and converts it to a permanently bound chemical energy in the biomass of all living things on the Earth.

How big can this effect be? Well, each day the amount of solar energy that the Earth received, if it could all be converted to mass would be about 167 tons (see calculation on Wolfram Alpha ) So, if the Earth could capture all that radiation each day and convert it all to mass, the mass would increase by 167 tons each day. Over the 4.5 billion year lifetime of the Earth that would only amount to a 4 millionths of 1% increase in the mass of the Earth.

The actual effect will be much much smaller than that since most of the solar radiation is radiated back to space as infrared radiation due to the average temperature of the Earth. In addition, life comes to an equilibrium where there is about as much biomass being created each day as there is biomass degraded each day. When wood is burned, for example, the heat produced is equivalent to some of the Solar energy the tree had absorbed when the wood was grown.

So the effect is very very small and is totally insignificant. A much more significant mass gain effect which accumulates continually through the Earth's life time is the mass of the micrometeorites and meteors that strike the Earth each day. That is estimated to be about 10 tons per day and that does not come to any kind of equilibrium - it just continually adds 10 tons of mass per day to the Earth. However another effect causes an even larger mass loss per day - the loss of about 250 tons of the Earth's atmosphere each day. So the net of all these very tiny effects is that the Earth is actually losing mass (and hence gravity) each day - but the loss is very insignificant.

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    $\begingroup$ I signed up just to ask about it: does converting sun's energy to a permanently bound chemical energy really increase the mass? It seems completely wrong to me, but I'm far from a physics buff, and would love to be (meaningfully) contradicted. By extension, are you claiming that the total mass of products of burning is smaller than that of the burned wood plus oxygen consumed? I was under the impression that chemical bounds are mostly massless, and to actually create (or annihilate) mass, quite different processes are needed (as opposed to chemical reactions). $\endgroup$
    – tomasz
    Oct 17 '15 at 13:54
  • $\begingroup$ @tomasz you could post this as a new question, and link to this one for reference. $\endgroup$
    – trichoplax
    Oct 17 '15 at 14:59
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    $\begingroup$ @tomasz physics.stackexchange.com/questions/195696/… $\endgroup$
    – user10851
    Oct 17 '15 at 22:46
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    $\begingroup$ 10 tons per day???! Woah.. Wait, 250 tons per day?!?!?! Wow! $\endgroup$ Oct 18 '15 at 14:33
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    $\begingroup$ @FrankH: Thanks. FWIW, I wasn't questioning you; just shocked! $\endgroup$ Oct 19 '15 at 0:34
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Not much more or less than any other similarly sized mass on earth via absorption of extra-terrestrial radiation. $E = mc^2$ Even then it would be a very minute gain.

The human body is made up of minerals and vitamins from the earth, so we don't appear and have mass that wasn't already on the earth.

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