Author Topic: How much mass will have been me?  (Read 1364 times)

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Offline DanDanDan

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Re: How much mass will have been me?
« Reply #15 on: February 28, 2019, 07:47:47 PM »
Here's one way to look at what I'm describing here. When a coroner weighs a body and its individual parts, he drains them, I presume. What's left over is the "permanent" structure that I'm talking about. I'm not saying that they consider fluids and digestive materials to be

When it comes down to it, I guess this question has different answers depending on arbitrary assumptions. The assumption that I'm making, arbitrarily, is that the transient elements of the body (i.e. that materials that are consumed, used, turned into byproducts, and expunged), don't count.

Does anybody know how a coroner approaches this issue?
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Offline fred.slota

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Re: How much mass will have been me?
« Reply #16 on: February 28, 2019, 10:04:12 PM »
A mouthful of food can be spit out, so I'll consider that not (yet) part of your body.
A lungful of oxygen can be exhaled, so I'll consider that not (yet) part of your body.
A stomachful of food can be regurgitated, so I'll consider that not (yet) part of your body.

But, when the sugar has been dissolved and the oxygen absorbed, both into the bloodstream, and migrates into the cells where the individual molecules are metabolized, I think at that point it is part of your body.
And, when the produced CO2 and water work their way out of the cell and back into the bloodstream and interstitial spaces, it's still part of your body.

A lungful of CO2, a bladderful of water (or sweat, or tears, or exhaled vapor, etc.), no longer part of your body.

So, in a rough calculation, over a lifetime about 15,000 kg of caloric food and 16,827 kg of O2 will pass through your body, producing about 8,709 kg of water and 23,142 kg of CO2.

15 Mg of sugar would be a sugar cube about 2.11 m on a side.
8.7 Mg of water would be a cube about 20 m on a side.
The O2 and CO2 would each be about 11.779 megaliters in volume at standard temperature and pressure, or about 412,267 typical party balloons, or about 40 Carl Frederickson House's worth of balloons.

Offline brilligtove

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Re: How much mass will have been me?
« Reply #17 on: March 01, 2019, 12:01:55 PM »
This week's No Such Thing As A Fish podcast has a discussion about this in the first section. Their accuracy is questionable, but their sources are usually good.
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Offline DanDanDan

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Re: How much mass will have been me?
« Reply #18 on: March 03, 2019, 04:18:12 AM »
Holy crap, I go away for a couple of days and you guys solve a problem I thought would never be solved! Thanks so much!

So, in a rough calculation, over a lifetime about 15,000 kg of caloric food and 16,827 kg of O2 will pass through your body, producing about 8,709 kg of water and 23,142 kg of CO2.

15 Mg of sugar would be a sugar cube about 2.11 m on a side.
8.7 Mg of water would be a cube about 20 m on a side.
The O2 and CO2 would each be about 11.779 megaliters in volume at standard temperature and pressure, or about 412,267 typical party balloons, or about 40 Carl Frederickson House's worth of balloons.

Oh man, that's another aspect to this that I hadn't even thought of. How do you measure gasses with a variety of weights in different states? I guess that shoots down the idea of getting a straightforward answer in "x" number of pounds or kg. Still 11.779 megaliters, wow!

This week's No Such Thing As A Fish podcast has a discussion about this in the first section. Their accuracy is questionable, but their sources are usually good.

I will definitely check out that podcast.

Thanks folks!
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Offline The Latinist

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Re: How much mass will have been me?
« Reply #19 on: March 03, 2019, 08:44:36 AM »
As you note, there are many questions which must be decided before one can even begin to think about such a calculation, the biggest of which is philosophical: what does it mean to be part of the human body?  What should we count? Water? Dissolved gasses? Mass that never leaves the alimentary canal? Bacteria? Surface dirt? Relativistic mass?
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Offline jt512

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Re: How much mass will have been me?
« Reply #20 on: March 03, 2019, 10:20:54 AM »
As you note, there are many questions which must be decided before one can even begin to think about such a calculation, the biggest of which is philosophical: what does it mean to be part of the human body?  What should we count? Water? Dissolved gasses? Mass that never leaves the alimentary canal? Bacteria? Surface dirt? Relativistic mass?

I think if one is willing to define everything between the skin and the alimentary canal as "you," it would not be too difficult to come up with a reasonable estimate.  So defined, over your lifetime everything you absorb from your diet plus all the oxygen you breath becomes "you" at some point in your life. 

So you would have lifetime mass of:

(food and water consumed) + (oxygen consumed) – (dietary fiber and unabsorbed nutritents) .

It would not be hard to come up with reasonable estimates for each of these factors.
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Offline arthwollipot

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Re: How much mass will have been me?
« Reply #21 on: March 03, 2019, 08:31:05 PM »
I will definitely check out that podcast.

No Such Thing is one of my top favourite podcasts.
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Offline Tassie Dave

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Re: How much mass will have been me?
« Reply #22 on: March 04, 2019, 05:17:42 AM »
I will definitely check out that podcast.

No Such Thing is one of my top favourite podcasts.

Mine too.  8) They do take a few liberties with the facts though (As does QI), but it's a lot of fun.


Offline daniel1948

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Re: How much mass will have been me?
« Reply #23 on: March 04, 2019, 09:18:01 AM »
I see two very different ways to interpret the original question: one way would be to regard everything except the contents of the alimentary canal as "part of me," which would yield a much higher number as water is constantly and rapidly being filtered out of the blood stream and replaced; and the other would be to take only solid structure as "part of me," which would give a much smaller number as only structural components are being lost and replaced.

Most of the food we eat is processed for energy, with the help of oxygen from the air, and never becomes part of our solid structure, but it does go through the metabolic cycle so is part of the chemistry of the cells, minus the portion that just goes through the gut without ever being absorbed.

An answer to the question requires a better definition of the question.
Daniel
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Offline fred.slota

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Re: How much mass will have been me?
« Reply #24 on: March 04, 2019, 10:25:48 AM »
As is true of many questions.

Offline amysrevenge

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Re: How much mass will have been me?
« Reply #25 on: March 04, 2019, 10:57:55 AM »
I think for a conceptual "me" it would be the most useful to take an instantaneous snapshot, consider the 3D envelope of the snapshot, and try to justify what matter inside that envelope you would and wouldn't count, until you've accounted for all matter. 

You could right away add to the "me" pile any cells, living or dead, that have or had DNA in them.  Obvious. 

Fluids are probably safe to count in the "me" pile too, but this might be more contentious.  I don't think you can separate out the fluid bits of blood from the blood cell bits of blood, in a conceptual sense.


Transients are where it gets really hard to quantify what counts and what doesn't.  Ultimately on an atom-by-atom basis it's all transient, so there has to be some sort of arbitrary distinction between "permanently part of the body" and "just passing through".  I don't reckon there's a "right" answer to that.  I have a subjective line (gases - not me, liquids and solids - me)
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Offline daniel1948

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Re: How much mass will have been me?
« Reply #26 on: March 04, 2019, 01:04:09 PM »
I think for a conceptual "me" it would be the most useful to take an instantaneous snapshot, consider the 3D envelope of the snapshot, and try to justify what matter inside that envelope you would and wouldn't count, until you've accounted for all matter. 

You could right away add to the "me" pile any cells, living or dead, that have or had DNA in them.  Obvious. 

Fluids are probably safe to count in the "me" pile too, but this might be more contentious.  I don't think you can separate out the fluid bits of blood from the blood cell bits of blood, in a conceptual sense.


Transients are where it gets really hard to quantify what counts and what doesn't.  Ultimately on an atom-by-atom basis it's all transient, so there has to be some sort of arbitrary distinction between "permanently part of the body" and "just passing through".  I don't reckon there's a "right" answer to that.  I have a subjective line (gases - not me, liquids and solids - me)

So poop counts but farts don't? ;D

The problem seem to be in the concept of what is "me" and what isn't. Maybe we should ask instead, "How much mass will have passed through me?" Then we can count everything. And since everything comes out eventually or is left over in me when I die, all we would have to calculate is how much goes into me from the time I'm conceived until I die, and then subtract any atom that has been in me before and has come around a second time, ot a third, fourth, etc.

I suspect that the number of atoms that make a repeat appearance would be huge, but would represent a minuscule percentage, and could safely be ignored if we're calculating down to, say, hundredths of a gram. Then we just have to figure out how much cumulative mass the average person eats, drinks, and inhales in a lifetime. There's probably close to an order of magnitude of variability between people who live an average lifespan.

Daniel
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Offline fred.slota

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Re: How much mass will have been me?
« Reply #27 on: March 04, 2019, 01:44:59 PM »
In my back of the envelope estimate of total metabolism throughput, the total of Oxygen atoms passing through in the lifetime is 1,533,735 mole, or about 9*1028 atoms.  That's a lot.

But, there appears to be about 6.75*1049 Oxygen atoms in the entire Earth.  At a ratio of 1:1021, I think we can safely say "miniscule percentage".  What's the inverse of an 'astronomical number'?

Offline jt512

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Re: How much mass will have been me?
« Reply #28 on: March 04, 2019, 04:06:16 PM »
In my back of the envelope estimate of total metabolism throughput, the total of Oxygen atoms passing through in the lifetime is 1,533,735 mole, or about 9*1028 atoms.  That's a lot.

But, there appears to be about 6.75*1049 Oxygen atoms in the entire Earth.  At a ratio of 1:1021, I think we can safely say "miniscule percentage".  What's the inverse of an 'astronomical number'?

Infinitesimal?


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Offline jt512

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Re: How much mass will have been me?
« Reply #29 on: March 04, 2019, 04:29:20 PM »
Quote
I suspect that the number of atoms that make a repeat appearance would be huge, but would represent a minuscule percentage, and could safely be ignored if we're calculating down to, say, hundredths of a gram. Then we just have to figure out how much cumulative mass the average person eats, drinks, and inhales in a lifetime. There's probably close to an order of magnitude of variability between people who live an average lifespan.

An order of magnitude?  No way. A factor of 2 would be pushing it.


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