According to this from the Master, the amount of matter that I converted into energy today is approximately .00000000012558 kg. When I add in 5 billion of my closest friends, I get .6279 kg. Now we’re talking. But human life is but an insignificant fraction of the life on earth. How much matter is the rest of life converting?
Are you just looking for how much, or are you supposing that the earth’s weight is decreasing steadily? Cuz, we do pick up quite a bit of space dust, etc. to offset the amounts that we burn and send into space.
Tomcat,
According to this link the earth gains from 10,000 to 100,000 tons a year due to space dust etc. I’m wondering if life is burning more or less than that. We don’t want to run out of earth.
Well this site say the biosphere is 1841e12 kgs. http://hypertextbook.com/facts/2001/AmandaMeyer.shtml That includes all living things so lets say 50% of that mass is animal. Lets also say that you energy mass conversion of 1.2e-10 kg /day is for a 100 kg animal. Lets also say that that is universal and constant through time. That mean for every kg of animal 1.2e-12kg is “lost” each day. Now over 600 million years it is a lot of mass ~2.4e16 kg “lost” but if you look at it over a period of 1 day its only 1.1e5 kg or 110 tonns which is well under the arrival of mass from space.
I’ll now sit by the bar waiting for my math to get knocked over.
I don’t think the loss of mass from burning fuel (or digesting food) is permanent the way it would be if we were actually shooting the mass out into space. What you’re losing is the mass-equivalence of the energy that’s stored in the chemical bonds in the food/fuel. But those chemical bonds, and the mass-equivalence of the energy in them, can easily be restored.
Suppose a cow eats a quantity of grass. When the cow’s done, you’ll have a slightly heavier cow, and a lot of cow manure. If you weigh the cow and the manure very precisely, you won’t have quite as much mass as you started with. But you get the missing mass back, so to speak, when the manure is re-incorporated into other high-energy bondings by other chemical processes, like when it’s used as fertilizer to grow more grass. On average, this kind of action can’t change the mass of the planet, as long as the byproducts (manure, exhaust, what have you) remain a part of a functioning biosphere.
Then again, maybe you’re just being funny. :smack:
I think KRM is thinking along the lines of the body heat leading to a loss in mass.
The energy we get from burning food comes from plants that used sunlight to convert simple molecules to complex molecules. Digesting food reverses that process. The important point here is that the energy comes from the sun and we’re not burning up the earth when we digest food. Or for that matter, when we burn wood or a fossil fuel.
Generally this is true for most life on Earth. The main exception would be the plants and animals that live around deep sea vents and get their energy from the earth. But I suspect that the sun is going to heat up and evaporate the seas long before that puts a significant dent in the mass of the Earth.
Converting mass to energy within a system does not really change the mass. If I have a closed box with a particle and the corresponding anti-particle, The mass of the box does not change if the two particles combine and are converted to energy.
Unless the energy leaves the system, the mass does not change. The only way this could happen (that I can think of off-hand) is by heat radiation.
DrMatrix,
In the link in the OP, Cecil states
It’s not observable in our case, but it does exist, right?
But as dtilque pointed out, the energy ultimately comes from the sun. Unless we’re doing some cool fission/fusion no one noticed the energy released is ultimately from outside our biosphere. Therefore no loss of earth mass. Too bad, I liked the numbers I came up with too. 
With few exceptions, not observable is the same as non-existence. The change in mass only becomes observable when the kinetic and heat energy is removed from the system.
Got it. Thanks DrMatrix and dtilque.
**grey, ** I liked your numbers too. That was the kind of answer I was really looking for.
The great tragedy of science, the slaying of a beautiful hypothesis by an ugly fact. T. H. Huxley.
Well the numbers are a complete “wag”. They do make the point that the biosphere releases 10e22 J of energy each day. Don’t tell the Matrix guys they’ll freak.
But we have launched a few tons of junk from beyond the earth’s gravity well in the form of exploratory probes.
I’m tempted to include the parts of lunar landers and other man-made objects which are still on the moon, but I’m afraid someone will then point out that the earth-moon system is actually a double planet system, etc.
But the earth DOES lose mass as the core undergoes nuclear fission. The missing mass is turned into heat-energy in the core, which moves on up to the surface and is eventually radiated out into space.
I don’t have any numbers on it though, and guess that it’s trivial compared to the addition of space dust and loss of gasses from the upper atmosphere.
Uhm…well no the core does not undergo fission. There are elements within the earth that are naturally radioactive (thorium) and release energy that way but not the core specifically. The core is solid nickel/iron and is hot simply from gravitional compression. Eventually the earth will cool to a nice hunk of solid rock.