How old am I?

[Gweedo]

This has been bothering me for a while:

How old are the atoms that constitute my body?

Is it possible that some of the hydrogen atoms within the water molecules within my body were formed as part of the big bang?

[Capricorn]

If I recall everything gets replaced over either 6 years or 8 years, that includes bones, the whole lot.

Think it was 6.

So you are no more then 6.

Start acting your age.

[Gweedo]

I think that there are some cells within your body that don't get replaced - your teeth for instance.

I take your point; the cells may be changing all the time (I think that the cells in your digestive tract and blood are the most short lived) but how old are the atoms in those cells?

[Beulah]

Capricorn,

I thought it was seven?

Neurons are never replaced, therefore they are among the oldest parts of your body, including some muscles in the heart.

[cathalferris]

The protons and electrons are generally not created new (notwithstanding some unlikely cosmic-ray interactions iirc). So the actual constituents of the matter aroudn us may be the age of the universe old... But we have no way to date (non-radioactive) atoms given that there isn't a known aging process that we can measure..

[virtualpilot45]

Protons are expected to degenerate by the year 1,000,000,000,000,000,000,000,000,000,000,000,000 (4 'billions') so you'll know when your entire body falls apart that time's getting on

[RogerTheDodger]

42

[Neilius]

Protons are expected to degenerate by the year 1,000,000,000,000,000,000,000,000,000,000,000,000 (4 'billions') so you'll know when your entire body falls apart that time's getting on

Actually it's 100 + 8 Trillions of years for proton degeneration. Hopefully, I'll have found Neptune by then.

[virtualpilot45]

Actually it's 100 + 8 Trillions of years for proton degeneration. Hopefully, I'll have found Neptune by then.

Know the feeling Seriously wishing I had a GoTo just for this sneaky planet!

[ollypenrice]

I'd recommend The Magic Furnace, the story of atoms by Marcus Chown. A wonderful book.

Olly

[vlebo]

Correct me if Im wrong but do we not start out as a single cell which when fertilised begins multiplying and we grow as a result of what we ingest and from nutrients supplied from our mothers , so therefore are we not as old as that single cell and whatever it contained ? I can barely stumble out of bed at 52 , if I find out I am a few billion year old , forget it !

[acey]

Is it possible that some of the hydrogen atoms within the water molecules within my body were formed as part of the big bang?

Yes, most of the protons in your body will have formed about 3 minutes after the big bang. And they've been in lots of other bodies/places/things before the (cosmically very brief) time they spend in your body. So enjoy them while they're yours!

Big Bang nucleosynthesis - Wikipedia, the free encyclopedia

[Macavity]

Thought provoking - half your genetic inheritance (maternal) was laid down in the

body of your grandmother? Hmmm... 1919. No wonder it's showing it's age!

And, what is it they say - Each time you breath, your inhaling a FEW molecules

of Julius Ceasar's dying breath. "Et", "tu", or "Brute", one wonders...

[umadog]

The molecules and atoms making up the neurons are also turned over. So in a sense the neurons you have now aren't the same as the ones you had a year ago.

[MontyUK]

13.8 billion years, give or take a few million.

Old-timer!

[banner001]

Know the feeling Seriously wishing I had a GoTo just for this sneaky planet!

i found neptune fairly easily last night...and im not using any fancy electronics it just looks like a small star in my 20mm Meade EP.

as for the 'age' of atoms in your body, some will be variable.

take radioactive phosphate-32, this decays to stable sulphur-32, the half life being ~14 days. so some atoms in your body will only be a few hours or days old.

now the constituent protons and neutrons can again be changed through various radioactive events although these are incredibly unlikely events to happen inside you (im thinking electron capture and neutron decay)...but technically possible.

now for the constituent parts of the protons and neutrons (quarks) and the electron cannot change into something else...i.e. a 'up' quark will always be an 'up' quark...now there is a process called 'neutrino oscillation' whereby neutrinos can change flavour (between muon, tau and electron)...but as neutrinos can pass through a light-year length of lead without interacting with anything...the likelyhood of your body capturing one is 0%.

[sgazer]

as I've doubled in weight in the last 25 years, at least 50% of my body is less than 25 years old, although you wouldn't think so by looking LOL!! I think it must be all internal.