Does Earth's Mass Change?

Also, though we mine minerals, metals etc to produce the objects on the planet, reproduction of all species changes the mass on the planet on a daily basis, by a lot. Yes, all species lose members but biodegradation takes time, and we are producing more of each species than we are losing, especially humans. Some species are going extinct though and I also wonder if the overpopulation of humans will ever reach the weight of the dinosaurs?

From what I recall, reproduction is a chemical process that doesn't increase mass - only changes form.......

Does the mass of the Earth increase with the increasing population? If not, why not?

I know several friends who have recently had a baby. You probably know someone who just had a baby too, because across the world about three babies are born every second! About 90 million new people come into the world every year. If an average baby weighs about 6 pounds at birth, then we're looking at roughly 500,000,000 pounds of baby every year, about the mass of 50,000 full grown elephants. Still, this two hundred million kilograms of new babies is only 0.000000000000004 % of the total mass of the Earth (6*10^24 Kg). In fact, the total biomass of the planet (all plant and animal matter), is roughly only 0.00000003% of the total mass of the Earth (most of that biomass is in forests).

So, even if all the babies born did add to the mass of the earth, it would hardly be noticeable. But the population changing doesn't change the mass of the Earth. Before a baby is born, it grows inside its mother. When someone grows, baby or otherwise, they're not adding to the mass of the planet; rather,they're converting other mass into them. In some sense, you really are what you eat. If you eat a hamburger for instance, your body breaks that food down into molecules and atoms, incorporates what it can use into your body, and passes what it can't use out as waste. You're just taking matter from something else and incorporating it into yourself. The famous chemist Antoine Laurent Lavoisier did a series of careful experiments back in the 1780's that showed mass was not created or destroyed in chemical reactions. By performing chemical reactions in sealed containers, he showed that the total mass is conserved. If you burn something like a piece of wood, the ash left doesn't have the same mass as the log, some of the mass of the log has escaped in the smoke. However, if you could keep track of where all the atoms from the log went up in smoke, you'd be able to tell that the total mass of the log and the air involved in burning it hadn't changed when it was smoke and ash afterwards.

Incorporating food into your body is a much more complicated chemical reaction, but also doesn't change the amount of mass on Earth. In the case of an unborn baby, most of the digesting is done by the mother, but the baby still converts the matter she passes to it into baby.

There are ways that the mass of the Earth can change. For instance, the lunar rover was left on the Moon by the Apollo astronauts, so that mass is no longer part of the Earth. Meteorites that crash into our planet, or even burn up in our atmosphere, can contribute some small mass to the planet. One of the most famous equations in physics, E=mc^2, actually tells us another way for total mass to change. Albert Einstein put forth the idea that matter and energy are just different forms of the same thing. Matter can be changed to energy, and vice versa. It doesn't happen much on Earth, but the massive amount of energy coming out of our Sun actually represents a gradual decrease in the Sun's mass. But that's a subject for another 'Ask a Scientist."

Lots of pseudo-science here, and "I think..." comments. The earth is essentially a closed system - there is mass addition through space debris (meteors, comets, iceballs, bolides, and so forth) entering the earth's atmosphere everyday. There are also annual mass loss due to atmospheric gas escaping (mostly helium & hydrogen), plus mass hurled into space by humans (rockets, satellites, and so forth0. The point here is that growth of biological organisms occurs through ingestion and utilization of elements and compounds already part of the earth's mass balance. Babies, and all biological organisms, eat "food" of one type or another to add mass (and eject a bit as well), but this mass is taken from the earth's overall mass - the closed system mass is simply transformed to fit energy and structural requirements.

Break down the human body: it is mostly water with various chemical compounds and elements. These units are taken from the earth's closed system. Atoms are neither created nor destroyed, simply re-arranged - thus, no addition to mass of the earth regardless of how many humans or puppies or bacteria. Basic natural science - chemisty and physics.

Best,

Geokeith

I often wonder what would happen if ALL the planes in the world were to take off and go airborne at the same time... How would that effect the Earth and it's gravitational pull... Great. Now I have a headache...

Vance