Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: life, death, and energy conservation

Learn more physics!

Most recent answer: 05/02/2014
Q:
My physics teacher brought up a good point, if the phenomena of energy conservation were true, then when we die and the energy from our cells leaves them, then is there a special area a "heaven" where are life energy would go?
- Ted. M (age 19)
Valporaiso, IN
A:

You're kidding- your physics teacher brought this up? By energy, we mean a specific measurable physical quantity, which shows no particular dramatic difference when something dies. For warm-blooded creatures, some thermal energy gradually leaks into the environment, if the environment happens to be a bit cooler than living body temperature. We don't mean all sorts of interesting features of how something behaves, which of course do change dramatically when something dies. So conservation of energy doesn't even lead to any interesting questions in connection with death, much less any imaginative answers.

Mike W.


(published on 10/22/2007)

Follow-Up #1: energy and life

Q:
Mike, would it not be best to dodge a question with a simple truth? That truth being that (specifically people and animals) when we are alive have energy, both chemical and electrical, and although we do not know enough about it we also do not know what happens to this energy when we cease to be alive. It is reasonable to think that this energy MIGHT follow the laws we know about other energy and the conservation of energy. Thank You
- Bob T. (age 47)
Bellefonte, PA
A:
Bob- We can measure things like temperature, chemical composition, etc. Those are the sorts of variables we use to keep track of ordinary forms of energy. If something odd happened to them when people die, then we would have to figure out where some extra energy went to or came from. But nothing odd does happen, so there's no mystery to account for there.

Maybe an analogy will help. When your car is running, there's an interesting flow of energy of a variety of types through the engine, electrical system, and so forth. When the car is off, most of that flow ceases. The energy itself doesn't disappear or do anything surprising or hard to explain. The thermal energy in the hot engine gradually leaks into the environment, etc.

Any of our basic laws might ultimately turn out to be wrong in some circumstances. In testing the laws, however, we try to look for circumstances where there's some theoretical reason to suspect we're near the edge of their range of validity. Just randomly picking events and guessing, for no particular reason, 'maybe the laws don't work here' is a pretty inefficient way to proceed.

Mike W.

(published on 10/22/2007)

Follow-Up #2: vis viva?

Q:
The problem is you cannot compare animate with inanimate i.e. a car to a person for example. In a person the energy is created from within. With a inanimate object it is a flow of energy passing through the device to create sort of purposful work. It is a fair question to try to understand what happens to the energy in person at death; it is not simply a device turning off because the device i.e. the body stops and the energy source stops. All the micro-energies from every cell including memory does go somewhere and it does not dissapear because nothing disappears, not matter not energy.
- JV (age 30)
MA
A:
We aren't saying that energy disappears, if by energy you mean the quantity that appears under that name in physics. Energy in living things does not come 'from within'. In some, it comes in mainly via sunlight. In others, it comes in mainly via food.

Whatever is special about life, all the amazing organized activity, the subjective sense of consciousness, and so forth is not the same thing as 'energy'. We have no physical reason to believe that those interesting and important other attributes are 'conserved', even though energy is.

Mike W.

(published on 10/03/2009)

Follow-Up #3: Energy and life revisited

Q:
MW you attempt to dart away from every question whose answer isn't currently explainable by making unrealistic comparisons, using fancy terms, and stating the question isn't reasonable because, in your opinion, it doesn't matter
- Kormak (age 23)
Canyon Hills, CA, 92532
A:
Trying to be polite to people who ask questions is not the same as 'darting away' from the questions. Still, it may not always be the best policy.

My claim is that there is no known conserved quantity which shows any unusual behavior when a living thing dies. There are things that are conserved, like energy, but they continue to be conserved in these processes. There are important things we care about that change, but there's no evidence that those things are conserved.

What exactly do you want to know?

You're invited to try to make some version of this question that:
1. Actually means something.
and
2. Makes no false assumptions.

Mike W.

p.s. I edited out the gratuitous and incorrect middle initial you gave me.

(published on 01/31/2011)

Follow-Up #4: What happens to neuron energy on death?

Q:
Okay, Mike, maybe you can explain the following so that we may better understand: 1) What exactly happens to all the action potentials on the neuronic membranes at the time of death? Those are measurable energies. 2) What happens to the electrochemical transfers in the bioenergetics system of the body at the time of death? Those are also observable and measurable. 3) And on the other end... regrading conservation of energy, what causes the very first action potential to be influenced and fired at the time a brand new thought is born in the mind, where no other thought has influenced that new thought. Take for instance the two scenarios of the creation of a unique new thought in an adult human, and the first-ever thought within the brain of a developing embryo or baby?
- SW (age 41)
Baton Rouge, LA
A:
1. Those action potentials (unequal ion concentrations across membranes) are maintained by active ion pumps. Those get their power from metabolic products, ATP, I presume. On death all those systems run down, with the energy all becoming thermal. It's very much the same sort of process that happens in any battery-powered circuit as the batteries run down, when they can't be recharged.

2. I'm not sure I know exactly which processes you are referring to here. The active processes stop, since there's no incoming free energy to drive them. Passive diffusion processes continue as things approach equilibrium.

3. This is a very philosophical question. I'm not comfortable with some of the implicit assumptions, in particular the idea that mental processes can be divided up into discrete thoughts with well-defined starting points. If one were to look at a system where such assumptions might provide a better model, a digital computer, the last thing one would worry about is energy conservation. All the little circuit elements obey energy conservation in a simple freshman-physics manner. Their collective behavior is interesting anyway.

Please follow-up if I've missed the point of some of your questions.

Mike W.

(published on 03/24/2011)

Follow-Up #5: Energy and power in human body

Q:
They say energy cannot be created or destroyed , so I also heard a human body has enough energy to power a dim lightbulb., When we die, does this mean our energy is never lost? I know any energy/nutritious things would go back into the ground but , where would our electrical charge go ? Back into the universe? Also I would like to know what happens to our consciousness and is it tied to our electrical charge?? Would it be possible to re-manifest your energy into another form after death? It's just so sad that we have to die and can never come back :( I must find a Way to live forever ... Also if our consciousness is not tied to our energy , how is it that we are conscious , what are the building blocks and mechanical mechanisms that make us conscious , please awnser all my questions D:
- Christopher (age 21)
Whittier ca USA
A:
Hello Christopher,
First of all, do not confuse power with energy.   Power is the rate of change of energy, expressed in Watts. The average power output of a human body at rest is between 90 and 100 Watts.  This about the same as a fairly bright incandescent light bulb.   However, this amount of power is used just to keep the bodily functions going, not to do useful work. Its net result is to heat up the surroundings.   It is claimed that a good long distance bicycle rider can have a sustained power output of 400 Watts or so.  I'm not sure, I've never tried it.
As for your philosophical questions about life, death, and energy conservation, I invite you to read some of our previous Q's & A's on this subject.  You can type in 5597 into the search box of the main page to find them. 

LeeH

(published on 08/22/2012)

Follow-Up #6: energy, life, and death

Q:
Okay, you have very good answers. But... the laws of conservation of mass and energy are laws, scientific proofs. I do not believe consciousness is the point here. That realm belongs to philosophy. I am a student and recently lost my father. I just finished a bit of chemistry. No physics yet. If I die my energy will be released thermally(heat=energy). Thermal energy is still energy being released into the environment until equilibrium is achieved. It does not cease to exist but comes to an equilibrium with the surrounding environmental energy(temperature). But what about mass? The atomic particles within me will be released back into the earth and atmosphere as gases and whatever is physically left after decomposition(dust?). In essence, these atoms live forever. Whether they become food for plants,coal,dust,environmental gases, they still continue to exist. Every atom. In the same sense that complete combustion of coal(in the presence of O) would create the products of co2 and h20. The end result is no longer coal, but a different set of compounds. Yet not an atom is lost. The thermal energy was stored in the bonds of the coal and released when combustion took place. Is this not true? In this sense everyone who ever lived continues to exist in particles and energy that become a part of the the greater universe. It is not a reversible reaction in the same sense that you cannot put back together a piece of paper that has been burned, but it is a reaction nonetheless. I find comfort in the fact that my dad still exists in the universe, conscious or not. But, I am an adult and do not need magical thinking to make sense of the world. Am I missing something? Are the laws of conservation flawed? The engine you present(iron,steel?) does not decompose quickly and its elements are not released when you turn the key off. It continues to be an engine(iron,steel?). It simply ceases to consume fuel(energy)and release that energy thermally. When a human dies, we do cease to consume fuel(Calories), but we do not continue in our physical form as a car engine would. That engine might, over a long period of time, rust, corrode, and oxidize, releasing its atoms into the universe as iron oxide, etc. Right? And those Fe & O atoms would again eventually be used for another purpose in the universe. That engine(and the fuel that made it go)performed its purpose and then returned to the chemical and energy universe. As I understand it, energy and matter only change forms. We are stardust. We symbiotically find another purpose that the universe has decided to use our atoms and energy for. Am I wrong? Please explain, I wish to increase my understanding of the science I am studying. Explain, I can take it.
- Jennifer (age 44)
Peoria,IL
A:

Everything you say sounds consistent with what we know of physics.

Mike W.


(published on 08/14/2013)

Follow-Up #7: where does life energy go?

Q:
When a person (or animal) dies, according to the law of conservation, could it be that the energy which was in that body alive is then converted to energy going out to the universe (or multiverse)? Thank you?
- Marilyn deVito (age 62y)
akron, Ohio, United States of America
A:

Yes, when a mammal dies it is usually surrounded by things that are cooler than body temperature. So a little heat leaks out into those surroundings. Also, most of the chemicals we're made of are not in low-energy states. They gradually fall apart, oxidize, etc. and the energy released also trickles out into the surroundings.

Mike W,


(published on 03/09/2014)

Follow-Up #8: Where does our energy go?

Q:
I think that this has been a great discussion. However, I think it should be clarified that matter and/or energy left by a living being would be burned up if it tried to exit our atmosphere. Hence these are not exiting to the universe; they are remaining trapped within our planet and its atmosphere. CD
- CD (age 40)
Sacramento, CA USA
A:

Actually, any heat energy on the Earth's surface does escape to far space, in the form of (mostly infrared) radiation. The way greenhouse global warming works is by slowing that escape process, so the Earth has to get hotter before the escaping radiation balances the incoming radiation from the Sun. 

Mike W.


(published on 05/02/2014)

Follow-up on this answer.