"Everything is a matter of perspective but to put things in perspective, it is useful to have a sense of scale."
That is what I said last week and it still stands. Scale allows us to get a perspective on the things around us. Indeed, there are some very interesting stories associated with indigenous people in jungle bound countries not having a good sense of perspective and therefore misjudging the scale of things.
But when scientists examine the world around them, the scale gets stretched.
Being a well-evolved, ape-like creature on the third planet of an undistinguished star in one of the spiral arms of the Milky Way, it is sometimes difficult to imagine the size of the universe and to put it into perspective. To help with this problem, scientists use powers of ten and orders of magnitude. From that perspective, the universe is some 26 orders of magnitude larger than you or I.
That makes the universe a very large place but it does give some sense of perspective as to just how large. What about the other direction though? How small is small?
Again, let's start at human scale objects things of a size typical in our surroundings let's say, about a metre.
At an order of magnitude smaller, we have the decimetre ten centimetres which is about the size a child's hand and a little smaller than a CD or DVD.
At an order of magnitude smaller, we have the centimetre a little less than a dime's diameter or that annoyingly small amount that I'm out every time I cut a piece of wood. Centimetres and metres are units that we use daily and certainly are familiar, although an amazing number of people still think in terms of feet and inches. I suppose when they start making five by 10s instead of two by fours, the metric system will finally truly take hold.
An order of magnitude smaller than the centimetre is the millimetre those fine lines that are the gradation on rulers. A millimetre is still a workable dimension about 10 paper pages thick. But it is generally too fine a scale for most things in our lives. Being a millimetre out, when cutting wood or measuring a room, is not usually going to affect the results.
A few more orders of magnitude - three to be exact - and at one millionth of a metre, we have the micron. This is a microscopic size, as its name implies, it is suitable for measuring the length of bugs and bacteria, the silicon chips of computers, and the precision required for the pieces that make up space craft and automobile engines. A micron is about the smallest useable unit for everyday objects around us.
At three orders of magnitude smaller, things are measured in nanometres one billionth of a metre. This is the dimension of molecules big molecules because atoms themselves are an order of magnitude smaller still.
The term nanotechnology is creeping into the vocabulary of politicians and venture capitalists as the new field of industrial research and manufacturing. All it means is materials built at a size comparable to large molecules. For example, a cholesterol molecule is about one nanometre across. A hundred gold atoms lined up side by side are around 20 nanometres.
Over the past 20 years, scientists have begun to understand how to build and control things at this order of magnitude in size.
At the Angstrom scale 10 billionths of a metre we have the atom. A large atom, such as lead, might measure three angstroms across but more common atoms, such as carbon and hydrogen, are a little smaller with a diameter that is typically one angstrom in size.
Below the atom, things get very tiny. At a distance of 10 to the minus 15 metres, which is a million billionth of a metre, we have the atomic nucleus and its constituent particles. Another order of magnitude will get us to quarks and gluons and all the other stuff that goes to make up sub atomic stuff. But that is about it. Somewhere around 10 to the minus 15th of a metre represents our lower limit of small.
All told, then, our universe is not such a big place. The total scale from smallest particle to the outer edges of space only spans a little more than 41 orders of magnitude. Of course, to put everything in perspective, that is still a 10 with 40 zeros trailing after it.
