LightPhoenix
First Post
For that matter (no pun intended), the Earth itself is not a closed system - the sun provides energy to the Earth, which is harnessed by plants.
Food, Energy, Waste
For that matter (no pun intended), the Earth itself is not a closed system - the sun provides energy to the Earth, which is harnessed by plants.
"Lost" mass is not really lost in that sense. It is converted into energy - light, motion, potential, or the like. It stays inside the Universe, be it open or closed.
Jack7
First Post
That was what I was saying in one sense, if the universe is a closed system. Nothing can really be lost, per se, in a truly closed system. Merely lost to observational limits.
There are however theories which posit that there are wormholes, or objects, black holes, etc. which allow transits or pathways to other universes (or dimensions.)
That goes well beyond the original question in part, but is germane to the idea of whether the universe is actually a closed or open system, and so can anything be truly lost, or even gained.
Of course then one has to define what exactly is a "universe," and where do the frontiers and limitations of a universe actually start and end?
If you define a universe as a given set of particular traits and forces, then it is self-contained, regardless of whether it is truly closed, or not, and can be differentiated between other universes, regardless of whether those universes can effectively interact.
If you define a universe as the summa esse (omnia), or suma in toto of all that can exist, does exist, or may exist, then there is in effect only one universe. (Though it still doesn't say it is necessarily closed as it may be infinite.)
But if universes are separate things, and can interact, then it is possible to "lose" things between them (matter, forces, energy, mass, etc). Though loses may equate through such interactions.
Of course that still remains both a theoretical and a definitional consideration.
In cosmology - the branch of physics that deals with such things - whether a universe is open or closed, and whether it is finite or infinite, are separate questions. If I recall correctly, there are ways a universe can, in theory, be infinite and closed.
Yes. Just to avoid confusion - There's no evidence of which I'm aware that chemical reactions (like in the OP) are one of those ways to lose tings form one universe into another.
Jeremy Ackerman-Yost
Explorer
Stepping back from physics to biology for a moment...
A large percentage of the food you take in exits the body as water, as someone alluded to earlier. Consider the mass of all the liquids you excrete, including sweat and water vapor in your exhalations. Someone above suggested that was a trivial amount. It's not. The average adult American loses about 3 lbs worth of water weight during 8 hours of sleep.
The vast majority of the energy you use is required just to maintain body temperature. Warm-blooded critters require 5-10 times as much food as comparably sized cold-blooded critters. This is a negligible loss of mass, but it does increase our intake enormously.
A large percentage of the food you take in exits the body as water, as someone alluded to earlier. Consider the mass of all the liquids you excrete, including sweat and water vapor in your exhalations. Someone above suggested that was a trivial amount. It's not. The average adult American loses about 3 lbs worth of water weight during 8 hours of sleep.
The vast majority of the energy you use is required just to maintain body temperature. Warm-blooded critters require 5-10 times as much food as comparably sized cold-blooded critters. This is a negligible loss of mass, but it does increase our intake enormously.
Jeremy Ackerman-Yost
Explorer
Yes. Usually 2-3 lbs of water. There's something of a fudge factor because urination wasn't controlled for in the data I saw.
Very Yes? much Yes? So Yes?
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