Hey it’s Professor Dave, let’s talk about cremation.
When someone passes away, they have the right to specify how they would prefer their remains
to be dealt with.
One obvious choice is to be buried in a cemetery, or some other location, something that humans
have been doing for thousands of years.
More recently, people have had the option of donating their body to science, helping
to train doctors and surgeons, or potentially aiding in the discovery of a cure to some
disease.
But a third option that is rather popular involves flame cremation.
This is where the deceased is placed in a large heating chamber, and reduced to pulverized
bone fragments, which we call ashes.
How does cremation work?
What exactly are ashes comprised of?
What can one do with the ashes once they are formed?
Let’s answer all of these questions as we get a closer look at the science of cremation.
As we said, cremation involves placing the deceased in fire.
This is not a new practice, humans have burned the dead on wooden funeral pyres for ages.
But this process has become much more sophisticated in modern times.
We now use specialized furnaces called cremators, which are fueled by natural gas or propane,
and the resulting fire reaches temperatures above 1,500 degrees Fahrenheit.
These high temperatures are possible due to the insulation offered by the cremator, often
made of a heat-resistant bricklike material.
The whole process can be operated digitally, so as to have total control over all aspects.
The body enters the cremator in something called an alternative container, which will
quickly cremate and leave little ash behind.
But the body will be a different story.
The human body is made of lots of water, many different carbon-based compounds, known as
organic compounds, and lots of bone, which is a connective tissue that contains inorganic
material, mainly calcium salts, in addition to organic material.
When exposed to the fire, most of the tissues and organs making up the body will vaporize,
forming gases that are released through an exhaust system.
The same can be said for all the water in the body.
But fragments of bone will remain after the cremation is complete, generally taking about
two hours, after which the bone fragments are allowed to cool.
They are then swept out and passed through a magnetic field to extract any metal particles
that may remain.
And then the bone fragments are crushed into a powder to produce the final product, which
we call a person’s ashes, about five pounds of grayish powder on average.
So what exactly is in these ashes?
Given that the majority of the components of the body have been vaporized, most of what
remains used to be components of the skeleton, which means a lot of carbonates and calcium
phosphate, along with trace amounts of other elements.
There will be slight variance from person to person, but the ashes will inevitably reflect
the composition of the human skeleton to a large degree.
Now what can be done with the ashes of a loved one?
Some people choose to place them in an urn and display them in the home somewhere.
Many request that their ashes be scattered in a particular place that held special meaning
to them, like a lake or a mountain.
But an additional fascinating option has been developed by companies such as Eterneva, and
that is to form a diamond using the remains.
Diamonds are made of carbon, as diamond is an allotrope of carbon.
Allotropes are different forms that an element can take, which means that carbon atoms can
come together to form a network solid in different ways.
Allotropes of carbon include coal, graphite, and even exotic materials like buckyballs
and carbon nanontubes.
But carbon atoms can also form diamond under the right conditions.
Now we did mention that the majority of the organic matter in the body is vaporized during
cremation, but nevertheless some carbon does remain, largely from the carbonates we previously
mentioned that are present in bone, and this carbon comprises between 1 and 4 percent of
the total mass of the ashes.
However, we can’t make diamonds out of carbonates, we need elemental carbon, or carbon all by
itself, so the carbonates have to be decomposed using a high-heat reduction process in absence
of oxygen, in order to get carbon in the form of graphite, without losing any carbon through
the production of carbon dioxide in the process.
This graphite is then superheated again to get rid of any impurities, leaving graphite
that is 99.995 percent pure carbon.
Then from this graphite, high pressure high temperature technology, or HPHT, is used to
simulate the crushing conditions of natural diamond growth deep within earth’s crust,
in order to convert this carbon from graphite into the diamond allotrope.
Huge pressures of around 870,000 psi and temperatures above 2,500 degrees Fahrenheit are applied
to mimic this astounding natural process, which forces flat sheets of graphite to adopt
the three-dimensional tetrahedral lattice of a diamond, thereby attaining the strength
and rigidity characteristic of this allotrope.
Apart from a small seed diamond the size of a grain of sand, which functions as the starting
point for diamond formation, a metal alloy that acts as a solvent, and the addition of
generic carbon to help grow larger diamonds, the end result is a diamond containing a significant
proportion of carbon atoms that were present in the body of the deceased person at the
time of death, making this a unique way to preserve the memory of a loved one.