A View from the Back of the Envelope top

Nanometers in your hands
10-9 meters per mm (Magnification of ×106)
Scaling the universe to your desktop
How Big Are Things?
Length Area Volume Speed
10 [ -6 | -3 | 0 | 3 | 6 | 9 | 12 | 15 | 18 ]
If bacteria were beachballs... 10-6 meters per meter

1 nm

10 nm

100 nm

1000 nm
10-9 m
0.3 nm
3 Å
3 nm
32 Å
10-8 m
32 nm
316 Å
10-7 m
316 nm
0.3 um
10-6 m
3162 nm
3 um

Atoms are around 0.2-0.3 nm
(grains of salt).
(Thus mostly 10-10, not 10-9...)

In gas (STP), atoms are ~3 nm apart, and mean free path is ~100 nm.

large molecules

Cell Membrane
7-10 nm thick
two lipid (fat) layers

LDL bloodstream colesterol carrier is a 22 nm ball of fatty stuff (1,500 colesterol with fat tails attached) surrounded by a single lipid layer (800 lipids and 500 regular colesterols). And a plug of docking hook protein.



1 nm per mm
Actual size (though rough, as screen resolution varies).




Carbon nanotubules are a few nm in diameter and many um long.

A View from the Back of the Envelope
Comments encouraged. - Mitchell N Charity <mcharity@lcs.mit.edu>

  Flesh out.
  Nanocrystals (grain sizes ~ 1-10 nm) are a delightful
    intermediate between atomic and bulk behavior.
  Lysosomes/microbodies vary in size from 0.2 to 2 um.
  phospholipid bilayer, miscelle
  bacterial memb/wall crosssection.
  viral spikes (herpes, 100nm isoc) are 10nm long
  SET wire ~16nm, dot ~12.

Digitized Electron Micrographs
The ball-like animal viruses from Electron Micrographs of Animal Viruses.
The stick-like plant viruses from Electron Micrographs of Plant Viruses:
  Tobacco Mosaic Virus x300,000  RNA, non-enveloped, monopartite
  Barley  Stripe Virus x300,000  RNA, non-enveloped, tripartite
  Maize   Mosaic Virus x150,000  RNA, enveloped  (bottom tubular)
  Maize   Streak Virus x300,000  DNA, non-enveloped (tiny double puffball)
150 dpi  9.5 x 7.5"  (0.2413 x 0.1905 m)
150 dpi  0.00666"/dot  1.693x10^-4 m/dot
            x3e5       0.6  x10^-9 m/dot   100nm = 167 dots
(Thus dot is how many atoms? :)
Shrunk by x2 to match animal viruses.
I wonder if they have the mag quite right on the Maize Streak - it seems small...

Should redo screen w 72 dpi?
Typical screen's 75 dpi(?) is 3.387e-4 m/dot ie 0.3387 mm/dot
Typical screen "real" scale: 0.3387 mm/dot  0.3387 nm/dot
  10 nm = 29 dots,  100 nm = 295 dots

Viral 100 nm bar is 73 dots, so 1.4 nm/dot

Bacteria structure

Calling atoms 10-9 m is pushing it, as many fall below
the 3.16 Angstrom threshold down into order 10-10.

Nanophase materials[link broken] have 1-100 nm grain sizes.

Retroviruses are 80 to 130 nm.
Carbon nanotubules are a few nm in diameter and many um long.
  (Nature 98 Jan 28 p466)
An ATP synthase (proton pumping <-> ATP) with spinning rotor
  10nm diameter and about 20nm high. (Nature 98 Jan 28 p510).

 2003-Feb-03  Repaired links - 3 fixed, 1 flagged, 1 left (bocklabs).
 2001.Apr.20  Added link to `How Big Are Things?'.
 1998.Jun.17  Corrected error with magnitude boundaries (3.333->3.162).
 1997.Oct.07  Added LDL.
 1997.Aug.19  Removed some viruses to speed loading.
Other meta info on zero magnification page.