Flatness/Smoothness

[jadyn]

I've been told that nothing known to man is perfectly flat/perfectly smooth. Is this true? I'm thinking in terms of real objects or materials here rather than anything theoretical.

Thank you.

[Count-A-Strong]

Perfectly true. If you look at anything under a microscope there will be a 'roughness' to the surface. I would imagine that the smoothest surfaces would be found on high quality optical lenses.

[jake-the-peg]

At some level there will be a roughness to anything because something that's perfectly smooth conforms to a theoretical straight line

If you get down to an atomic level you end up with electrons buzzing about

The Keck telescope is so smooth that if it were the width of the Earth imperfections would be only 3 feet high

http://keckobservatory.org/about/mirror/

However neutron stars are probably the most smoth natural objects. Their intense gravity means that on a 500m object imperfections are likely to be less than 5mm

[heathfield]

http://www.sciencedai...8/09/080922141139.htm

[neuron]

What about graphene?

[jake-the-peg]

Here's an image of Graphene

http://www.devicedail.../2008/09/graphene.jpg

like I say if you magnify anything enough you'll see roughness if even at an atomic level

[neuron]

Thanks Jake. I've read an article lately on graphene which showed a picture similar to the second one in the following link:

http://www.bbc.co.uk/news/world-11476301

I was clearly misled as this hexagonal lattice does appear to be smooth at first glance. Your link no doubt shows the true structure.

[neuron]

Jake, having looked at the photo you provided again on the device daily website, the text refers to graphene as being one atom thick. Surely if something is consistenly one atom thick throughout it's structure, then it must be flat? Or am I misunderstanding something here?

[gumboil]

I think neuron has a point. This article:

http://www.nanopaprik.../graphene-transistors

refers to graphene as being "smooth and flat".

Furthermore, this article:

http://arxiv.org/ftp/...pers/0702/0702595.pdf

refers to graphene as being a "flat monolayer of carbon atoms tightly packed into a two-dimensional (2D) honeycomb lattice". I think it's relevant that the latter article was written by scientists at Manchester University, where graphene was first isolated. the article also discusses the ability of graphene to be rolled into nanotubes etc which seems to require a flat, smooth surface.

[wildwood]

What about the inner surface of a bowl of mercury at room temperature.

[jadyn]

Hmm, I find it very odd that this thread has effectively stalled. What's the problem?

[sandyRoe]

Friction slowed it down?

[DTCwordfan]

the roughs are on duty this evening

[jadyn]

Lol sandyRoe.Whilst neuron's and gumboil's posts may have demanded a rethink,I had not expected total silence.

If their thinking is flawed, can someone please explain why. seems perfectly reasonable to me.

[mibn2cweus]

Not meaning to be sharp or abrasive, but isn't this question rather . . . pointless?

http://www.angelfire....ssinfo/questions.html

[vascop]

To provide an answer to this question (or any other for that matter) the words being used must be well-defined.
Nobody seems to have defined smoothness or flatness.
Jadyn: You need to say what the definition of these terms is otherwise the whole discussion is meaningless.

[Khandro]

I think the mercury idea is a no-no because it's surface will follow the curvature of the earth.

[Dagman]

My definition of Smoothness = if you scratch a surface with a fingernail and feel nothing then it's smooth, eg glass. Flatness = using a line if sight along an objects surface and seeing no dips or rises then it's flat, eg table top.

[mibn2cweus]

. . . well, at least it was, until you scratched it!

"Schrodinger, get that cat outta here!" ~ Heisenburg