..or is it just a case of determining it from the light measurement (lux?)?

Just wondering!

Isn’t the “Goth” the Si unit of darkness?

1.82m apparently

http://goo.gl/dDPZcc

Unless you’re talking about absolute darkness (total absence of light), then surely you just measure the amount of light present, however little?

Darkness being the relative lack of light, not total absence of.

Or something….

woody2000 – Member

Unless you’re talking about absolute darkness (total absence of light), then surely you just measure the amount of light present, however little?

Darkness being the relative lack of light, not total absence of.

Or something….

Dunno, but this sounds about right.

It’s analogous to noise, I think – you don’t measure the silence, but the amount of noise. If it is silent then there is no noise, if it is dark, then there is no light.

Measuring the amount of darkness is exactly the same as measuring the amount of light. In the same way as measuring poverty involves counting money.

If you can’t see the needle on the light meter it’s dark.

hth.

you don’t measure the silence, but the amount of noise. If it is silent then there is no noise

The Si unit for lack of noise is the “Shhhh”

In Devon its Called the “Dimpsey Scale”.
If its too dark to read but you can still see well the its “Dimpsey”.

Not as far as I know, but there are diff types of dusk– civil, nautical and astronomical

Not sure it helps but I thought it was pretty cool when I found out – I am very sad though …..

If you’re talking about darkness as in how little light there is in a room then you’d measure that as units of light. But if you wanted to measure how dark an object was – for instance how how dark a hue something is, and therefore how little light it reflects then thats ‘Absorbance’ and units of absorbance are called….. wait for it…. “Absorbance Units”

snimul

Be careful when asking how black something is..
[video]https://www.youtube.com/watch?feature=player_detailpage&v=wj84tfS7ag4[/video]

‘Absorbance’ and units of absorbance are called….. wait for it…. “Absorbance Units”

Actually Absorbance doesn’t really have any units (its a dimensionless quantity – being the log of a ratio!). Absorbance Units are an artificial construct by people embarrassed about not having a unit!

Interestingly (if you are so inclined!) the “darkness” of an object may not only be defined by its absorbance (which strictly only applies to light which is absorbed) – light may be scattered, interfered or reflected too and to the observer all contribute to ‘loss of photons’ which make the object appear darker. The optical density would be a more accurate description of the total loss of light from its interaction with an object.

Now coming back to the original question I’m not aware of any measure of darkness, other than measuring the absence of light. If you particularly wanted a unit of darkness which was intuitive so that increasing darkness resulted in bigger numbers the easiest solution would be to use reciprocal illuminance i.e. lx^-1 in that way you would find that a moonless night (just the stars) with no light pollution the darkness was ~ 10,000 lx^-1 a full moon about 1, and a very overcast day around 0.01.

Okay, i will risk the ban*

*Mods – feel free to delete this but…

Light to dark

Scottish
English
Spanish
Turkish
…

You get the idea. Sorry

I think “Pitch Black” is 100% dark.

It is the wOO.

Owls use it.

So do my kids when they are pretending to be ghosts. Or owls.

So do my kids when they are pretending to be ghosts.

Have you told your kids that ghosts have metal teeth?

And that they can only bite you if you believe in them?

I was a bad baby sitter 🙂