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List of holes

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From Molecupedia, the encyclopedia of very small things
This is the current revision of this page. The present address (URL) is a permanent link to this version.
Measured holes in science and engineering, ordered by width
For holes that count things, see Nanopore.
A dark oval opening seen through a microscope, with a red point of light near its center and small bright specks
The 200-micron laser-drilled pore of Molecular Reality Corporation's live stream, in dark-field microscopy. It is near the middle of the list.

This is a list of holes in science and engineering whose widths have been measured and published. It runs from the narrowest point of the channel that carries water through the membranes of red blood cells, about 0.3 nanometers across, to an open-pit diamond mine in Siberia 1.2 kilometers across, a span of more than twelve orders of magnitude.

Many of the narrow holes are used to count things one at a time. When a particle enters a hole filled with salt water, it pushes out some of the conducting liquid and the electric current through the hole dips. Wallace H. Coulter counted blood cells this way from 1948, and nanopore sensors count single molecules by the same Coulter principle, through holes about 100,000 times narrower.[1] A separate section lists things called holes that are not holes.

So that the table can be sorted, the width column gives every entry in nanometers. The company that publishes Molecupedia uses the same unit for a human hair, which its field guide puts at "about eighty thousand nanometers".[2]

Holes

Holes, narrowest first
Hole Width Width (nm) Location or maker Year Notes
Selectivity filter of the KcsA potassium channel about 0.3 nm 0.3 The soil bacterium Streptomyces lividans 1998 (structure) About 1.2 nm long. Potassium ions pass in single file after shedding their water. The structure was the first atomic picture of an ion channel.[3]
Narrowest point of aquaporin-1 about 0.3 nm 0.3 Membranes of red blood cells, kidney and other tissues 2001 (structure) About the width of one water molecule, so water crosses in single file and protons are kept out.[4] The discoverers of the water channel and of the potassium channel's structure shared the 2003 Nobel Prize in Chemistry.[5]
Constriction of CsgG 0.9 nm 0.9 Outer membrane of Escherichia coli 2014 (structure) The bacterium uses it to export the proteins of curli fibers. Engineered versions read DNA in commercial nanopore sequencing.[6]
Constriction of MspA 1.2 nm 1.2 Mycobacterium smegmatis 2004 (structure) No more than 0.6 nm long, so only a few DNA bases sit in it at once. It was used to read DNA from 2010.[7]
Narrowest point of alpha-hemolysin 1.4 nm 1.4 Staphylococcus aureus 1996 A toxin that kills cells by leaking them; its channel is 10 nm long. In 1996 it became the first pore to register single strands of DNA and RNA.[8][9]
Underpore drilled by focused ion beam 200 nm 200 demonpore, inc., Menlo Park, California about 2018 Drilled in silicon, with a blade that slid across it; the founder called it a "fully wet, stable 200 nm underpore". The team broke most of its pores "in the first week or so" while working out how to wet them.[10]
Coulter's cellulose acetate aperture 76 µm 76,000 Wallace H. Coulter 1948 Made in film 22 µm thick. Two weeks earlier, by Coulter's account, he had burned a first hole with a hot needle in the cellophane wrapper of a cigarette pack. "It didn't hold up long," he said.[1]
Aperture of the Coulter counter 100 µm 100,000 Wallace H. Coulter 1956 67 µm long, as described in Coulter's paper of 1956. Beckman Coulter's standard apertures now run from 10 to 2,000 µm.[1][11]
The 200-micron laser-drilled pore about 200 µm 200,000 Molecular Reality Corporation 2026 The pore of the company's live molecular stream, listed on its shelf of provisions as a "laser-drilled macropore".[12][13]
The knot sequencing hole about 2 mm 2,000,000 demonpore, inc. 2020 or 2021 Knots tied in a nylon filament were drawn through it, each one a dip in the current; the dips became the targets of the company's first game, Spyke Hunter.[14]
ISO 838 filing hole 6 mm 6,000,000 International Organization for Standardization 1974 Two holes 80 mm apart, 12 mm from the edge of the sheet, for binders and files.[15]
Center hole of the compact disc 15 mm 15,000,000 IEC 60908 1982 Fixed by the standard for the audio disc, which is 120 mm across.[16]
Hole on a golf green 108 mm (4.25 in) 108,000,000 The R&A 1891 At least 101.6 mm (4 in) deep. The R&A fixed the size in its rules of 1891; a hole cutter made at Musselburgh in 1829 had the same diameter.[17]
Kola Superdeep Borehole (SG-3) 23 cm 230,000,000 Kola Peninsula, Russia (then the Soviet Union) 1970 to 1989 Reached 12,262 m in 1989, the deepest point people have drilled. The rock at the bottom was about 180 °C, much hotter than predicted.[18]
Morning glory spillway of Monticello Dam 22 m (72 ft) at the lip 22,000,000,000 Lake Berryessa, California 1957 A bell-shaped overflow that drains the lake when it rises above the lip, narrowing to 8.5 m (28 ft) at the exit.[19]
Great Blue Hole 318 m 318,000,000,000 Lighthouse Reef, Belize A marine sinkhole 124 m deep, formed as a cave when the sea was lower and later flooded.
The Big Hole, Kimberley 463 m 463,000,000,000 Kimberley, South Africa 1871 to 1914 Dug by hand to a depth of 240 m, by up to 50,000 miners with picks and shovels, and yielded 2,722 kg of diamonds. Debris and water have since filled the bottom.
Mir mine 1,200 m 1,200,000,000,000 Mirny, Sakha Republic, Russia 1957 to 2001 An open-pit diamond mine 525 m deep. Mining continued underground from 2009.

Planned and uncertain holes

The MR1 Nanopore Reader, an open design published by Molecular Reality Corporation in October 2026 and in the public domain since October 21, specifies silicon nitride membranes 10 to 50 nm thick with pores 2 to 10 nm wide. None had been made in an MR1 when the design was released.[20]

In 2019 three chemists at the University of Rhode Island made nanopores in silicon nitride with the spark of a handheld electric lighter (Tesla coil lighter pore fabrication).[21] The company tried the method "for a night or two", and its founder's account of the result is "we may or may not have made pores".[22]

The arrays of micropores made in 2020 for the Molecular Aquarium, a chip on which one plate of pores slides over another, exist and have never been tested; in 2026 they sat on the founder's desk "as museum pieces".[12]

Keyholes

Few keyholes have published dimensions. The most visited is in the gate of the priory of the Order of Malta on the Aventine Hill in Rome: through it the dome of St. Peter's Basilica appears at the end of a garden path between clipped hedges, and visitors line up in the square outside to look.

The Keyhole series of American reconnaissance satellites took the name without the hole. Its KH-11 satellites, the first of which was launched in 1976, were the first in the series to send their images to the ground electronically instead of dropping film.

Holes in name only

Ozone hole
The region over Antarctica where the total ozone overhead falls below 220 Dobson units. It is a thinning, and ozone remains inside it. On September 24, 2006, it covered 29.5 million km² (11.4 million square miles), equaling the single-day record of September 9, 2000.[23] A circle of that area would be about 6,100 km across.
Black hole
A region of space from which nothing, including light, can escape. The one at the center of the Milky Way, Sagittarius A*, has about four million times the mass of the Sun, and the Event Horizon Telescope published an image of its shadow on May 12, 2022.[24]
Electron hole
In a semiconductor, the absence of an electron from an otherwise filled band of energy levels. It moves through the crystal like a particle with positive charge and carries the current in p-type silicon.
Eridanus supervoid
A region with unusually few galaxies, in the direction of an unusually cold patch of the cosmic microwave background known as the Cold Spot. A 2022 study with the Dark Energy Survey confirmed the underdensity and found that, under the standard model of cosmology, it explains only about 10 to 20 percent of the cold.[25]
The Hole World
An online atlas, published by Molecular Reality Corporation in September 2026, of the research groups and companies that work on nanopores and related sensors. Its build of September 26, 2026, held 2,112 entries.[26]
Holey Grail
The founder's name for reading DNA base by base with a solid-state nanopore, which no laboratory has published.
The Hole Enchilada
A section of the founder's 2025 essay on the company's role-playing game, retelling the invention of the Coulter counter.

See also

References

  1. ^ a b c M. D. Graham (November 18, 2020). "The Coulter Principle: For the Good of Humankind". University of Kentucky. Retrieved October 25, 2026.
  2. ^ "Keltar's Field Guide to Molecular Reality". Molecular Reality Corporation. August 2026.
  3. ^ Doyle, D. A. (1998). "The structure of the potassium channel: molecular basis of K+ conduction and selectivity". Science 280 (5360): 69-77. doi:10.1126/science.280.5360.69.
  4. ^ Sui, H. (2001). "Structural basis of water-specific transport through the AQP1 water channel". Nature 414: 872-878. doi:10.1038/414872a.
  5. ^ "The Nobel Prize in Chemistry 2003". Nobel Prize Outreach.
  6. ^ Goyal, P. (2014). "Structural and mechanistic insights into the bacterial amyloid secretion channel CsgG". Nature 516: 250-253. doi:10.1038/nature13768.
  7. ^ Derrington, I. M. (2010). "Nanopore DNA sequencing with MspA". Proceedings of the National Academy of Sciences 107 (37): 16060-16065. doi:10.1073/pnas.1001831107.
  8. ^ Song, L. (1996). "Structure of staphylococcal alpha-hemolysin, a heptameric transmembrane pore". Science 274 (5294): 1859-1866. doi:10.1126/science.274.5294.1859.
  9. ^ Kasianowicz, J. J. (1996). "Characterization of individual polynucleotide molecules using a membrane channel". Proceedings of the National Academy of Sciences 93 (24): 13770-13773. doi:10.1073/pnas.93.24.13770.
  10. ^ Kemmishtree (March 29, 2026). "Focused Ion Beam pore". EQBio-OS.
  11. ^ "Coulter Principle Short Course, Chapter 2". Beckman Coulter. Retrieved October 25, 2026.
  12. ^ a b "Company records". Molecular Reality Corporation. October 2026.
  13. ^ Lenora Ashgrove (July 29, 2026). "Nineteen Billion Ions a Second, Live on the Internet". Signal & Noise.
  14. ^ Kemmishtree (March 29, 2026). "Sequencing a string". EQBio-OS.
  15. ^ "ISO 838:1974, Paper: Holes for general filing purposes; Specifications". International Organization for Standardization. 1974.
  16. ^ "IEC 60908:1999, Audio recording: Compact disc digital audio system". International Electrotechnical Commission. 1999.
  17. ^ "What size is the golf hole, and why?" Golf Today.
  18. ^ "How Deep Is the Deepest Hole in the World?" Scientific American.
  19. ^ "Monticello Dam". Atlas Obscura.
  20. ^ "MR1 Nanopore Reader". GitHub. October 16, 2026.
  21. ^ "Push-Button Method To Create Nanopores Using a Tesla-Coil Lighter". ACS Omega 4 (1): 226-230. 2019. doi:10.1021/acsomega.8b02660.
  22. ^ Kemmishtree (March 29, 2026). "making pores with a $20 Tesla coil lighter". EQBio-OS.
  23. ^ "Antarctic Ozone Hole Is A Double Record Breaker". ScienceDaily. October 20, 2006.
  24. ^ "First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way". The Astrophysical Journal Letters 930 (2): L12. 2022. doi:10.3847/2041-8213/ac6674.
  25. ^ "The DES view of the Eridanus supervoid and the CMB cold spot". Monthly Notices of the Royal Astronomical Society 510. 2022.
  26. ^ "The Hole World". Molecular Reality Corporation. September 26, 2026.
Retrieved from "https://molecularreality.com/wiki/List_of_holes"
Last edited 2 hours ago by Debye Length Enjoyer