% % --------------------------------- % Scales of Measurement Version 1.8 % --------------------------------- % % This is a copy of the scales of measurement list that I have been % making. Thanks to the many people who gave me suggestions about earlier % versions. % % This is a plain TEX file and does not require any TEX macro files. One % should only need to edit out the usenet/email header and then % the file should be able to be passed through TEX. You do not need to edit % out this information and I would appreciate it if you would not so that if % later you give this file to someone else they will be able to send me % their ideas. The TEX page size variables are currently set for American size % paper and may have to be changed for other sizes of paper. % % I would be grateful for factual and grammar corrections. I % would also like to know if people have specific objects that they think % should be included in these scales. I am interested in objects which do % the following things: % % A. Illustrate a physical principle (for example, the Compton length as % a basic quantum "fuzziness" length) % B. Are particularly fantastic (for example, the LIGO project wants to % look for length fluctuations smaller than a nuclear diameter) % C. Fill in holes in my order-of-magnitude scale % D. Are especially interesting for some other reason % % I would be grateful for suggestions as to how to better word specific % entries so as to make them maximally illuminating in the available space. % Please send any comments/suggestions/corrections to me via email. % % An XMOSAIC page has been created for my timelines and scales of measurement % list. The URL is the following: % % http://www.astro.psu.edu/users/niel/scales/scales.html % % If you are not able to obtain one of my lists via XMOSAIC or usenet, please % send me an email request and I will email you the list you want. Please % specify desired format (ASCII or TEX). % % Thank you, % % Niel Brandt % niel@astro.psu.edu % % This document is copyright Niel Brandt 1994. You are allowed to copy, % distribute, and edit this document at will without any obligation as long % as you do not remove the above header. Reproduction and distribution for % personal profit is not permitted. %--------------------------------------------------------------------- % \vsize=11.0 in % \voffset=-0.8 in \hsize=7.0 in \hoffset=-0.4 in \vbox{ \noindent {\bf SCALES OF MEASUREMENT VERSION 1.8} \vskip 0.05 in \noindent {\tenrm William Nielsen Brandt --- \tentt niel@astro.psu.edu} \vskip 0.10 in } \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $3\times 10^{-6}$ & arcseconds & Angular size of a $10^8$ M$_\odot$ Schwarzschild black hole in M31\cr $0.0002$ & arcseconds & Typical VLBA resolution at 43 GHz\cr $0.0005$ & arcseconds & Person on the Moon\cr $0.001$ & arcseconds & Typical VLBI resolution\cr $0.001$ & arcseconds & Typical gravitational microlensing image angular separation\cr $0.0015$ & arcseconds & {\it Hipparcos} satellite astrometric positional accuracy\cr $0.04$ & arcseconds & {\it Hubble Space Telescope} FOC optical angular resolution\cr $0.1$ & arcseconds & VLA largest configuration resolution at 23 GHz\cr $0.1$ & arcseconds & {\it Hubble Space Telescope} WFC optical angular resolution\cr $0.15$ & arcseconds & 1 meter optical reflector yellow light diffraction limit\cr $0.5$ & arcseconds & WHT MARTINI guide star system resolution\cr $0.6$ & arcseconds & Rough optical telescope atmospheric seeing limit\cr $0.8$ & arcseconds & Angular diameter of Europa\cr $1$ & arcseconds & AXAF X-ray satellite angular resolution goal\cr $1.32$ & arcseconds & Yearly proper motion of Sirius\cr $1.75$ & arcseconds & Gravitational deflection of a light ray which grazes the Sun\cr $2.9$ & arcseconds & Angular diameter of a M31 sized galaxy at $z=0.5$ in optical light\cr $5$ & arcseconds & ROSAT X-ray satellite HRI angular resolution\cr $8$ & arcseconds & Angular separation of the gravitationally lensed quasar 0957+561\cr $25$ & arcseconds & ROSAT X-ray satellite PSPC angular resolution\cr $36$ & arcseconds & Angular diameter of Jupiter\cr $120$ & arcseconds & Human eye resolution\cr $120$ & arcseconds & Typical optical telescope field of view\cr $150$ & arcseconds & Rough Crab Nebula radius\cr $210$ & arcseconds & Rough Cir X-1 radio nebula radius\cr $400$ & arcseconds & Cluster imprint on the cosmic microwave background radiation\cr $480$ & arcseconds & OVRO 5.5 meter 32 GHz telescope resolution\cr $700$ & arcseconds & Jodrell bank 250 foot $1\, 420.4$ MHz telescope resolution\cr $1\, 200$ & arcseconds & ROSAT X-ray satellite HRI field of view radius\cr $1\, 500$ & arcseconds & ASCA X-ray satellite GIS field of view radius\cr $1\, 865$ & arcseconds & Angular diameter of the Moon at its mean distance\cr $1\, 800$ & arcseconds & 100 Mpc structure imprint on the cosmic microwave background radiation\cr $1\, 922$ & arcseconds & Angular diameter of the Sun at its mean distance\cr $2\, 700$ & arcseconds & Largest dimension of W50 (ARAA 22, 524)\cr $3\, 100$ & arcseconds & Maximum angular scale of causal connection on the cosmic microwave background radiation\cr $3\, 600$ & arcseconds & ROSAT X-ray satellite PSPC field of view radius\cr $10\, 800$ & arcseconds & Angular diameter of the LMC\cr $14\, 400$ & arcseconds & Angular diameter of M31 in optical light\cr $19\, 800$ & arcseconds & Palomar Optical Sky Survey plate field of view\cr $25\, 200$ & arcseconds & COBE DMR resolution limit\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $5\times 10^{-44}$ & seconds & Planck-Wheeler time$\ = \bigl({G \hbar \over c^5}\bigr)^{1 \over 2}$\cr $4\times 10^{-24}$ & seconds & Typical lifetime of strong interaction resonance$\ = {h\over m_{\rm p} c^2}$\cr $8\times 10^{-21}$ & seconds & Electron light crossing time$\ = {h\over m_{\rm e} c^2}$\cr $1\times 10^{-13}$ & seconds & Typical period of vibration of an atom in a solid\cr $1\times 10^{-13}$ & seconds & Typical X-ray line electric dipole radiative transition time\cr $1.6\times 10^{-9}$ & seconds & Typical hydrogen 2p$\rightarrow$1s radiative transition time (electric dipole one photon process)\cr $8\times 10^{-4}$ & seconds & Mass shedding minimum spin period for a neutron star\cr $1.6\times 10^{-3}$ & seconds & Spin period of PSR 1957+20\cr $0.12$ & seconds & Typical hydrogen 2s$\rightarrow$1s radiative transition time (strictly forbidden two photon process)\cr $10$ & seconds & Median duration of a classical $\gamma$-ray burst\cr $887$ & seconds & Mean life of a neutron in free space\cr $2\, 000$ & seconds & Sun dynamic time scale\cr $8.6\times 10^{4}$ & seconds & Earth rotation time\cr $3.2\times 10^{7}$ & seconds & Earth orbit time around the Sun\cr $1.6\times 10^{9}$ & seconds & Typical time between Milky Way supernovae\cr $1.9\times 10^{11}$ & seconds & Carbon-14 half-life\cr $3\times 10^{12}$ & seconds & Rough lifetime of a supernova remnant\cr $1.5\times 10^{13}$ & seconds & Typical HMXB evolution time\cr $3\times 10^{13}$ & seconds & Rough time for evolution of a biological species\cr $1.6\times 10^{14}$ & seconds & Main sequence lifetime for a 30 M$_\odot$ star\cr $3\times 10^{14}$ & seconds & Hydrogen 21 cm spin flip time\cr $3\times 10^{14}$ & seconds & Rough Lyapunov time of the solar system\cr $6.3\times 10^{14}$ & seconds & Sun thermal time scale\cr $1.3\times 10^{15}$ & seconds & E-folding time for a black hole accreting at the Eddington rate with an efficiency of 0.1\cr $1.9\times 10^{15}$ & seconds & Main sequence lifetime for a 5 M$_\odot$ star\cr $2\times 10^{15}$ & seconds & Timescale for Los Angeles to pass San Francisco via continental drift\cr $2.4\times 10^{15}$ & seconds & Typical LMXB evolution time\cr $7.3\times 10^{15}$ & seconds & Orbit time for sun around galaxy center\cr $1.1\times 10^{16}$ & seconds & PSR 1913+16 orbital gravitational radiation coalescence timescale\cr $2\times 10^{16}$ & seconds & Rough supernova biological extinction time\cr $6\times 10^{16}$ & seconds & Minimum age of PSR J0437--4715 (ApJ 411, L85)\cr $6\times 10^{16}$ & seconds & Time for galaxy to cross a cluster\cr $7\times 10^{16}$ & seconds & Radial period of the orbit of the Magellanic Clouds (MNRAS 198, 718)\cr $1.1\times 10^{17}$ & seconds & Primeval slime to man time\cr $1.5\times 10^{17}$ & seconds & Age of Earth and Sun\cr $1.5\times 10^{17}$ & seconds & Uranium-238 half-life\cr $2.7\times 10^{17}$ & seconds & Look back time to $z=1$\cr $3\times 10^{17}$ & seconds & Main sequence lifetime for a 1 M$_\odot$ star\cr $3.3\times 10^{17}$ & seconds & Look back time to $z=2$\cr $3.3\times 10^{17}$ & seconds & Sun nuclear time scale\cr $3.7\times 10^{17}$ & seconds & Look back time to $z=4$\cr $3.8\times 10^{17}$ & seconds & Rough age of the Milky Way\cr $3.8\times 10^{17}$ & seconds & Look back time to the $z=4.897$ quasar PC 1247+3406\cr $4\times 10^{17}$ & seconds & Rough age of 47 Tucanae (an old globular cluster)\cr $4.1\times 10^{17}$ & seconds & Age of the universe $= {2\over 3 H_0}$\cr $2.5\times 10^{18}$ & seconds & Globular cluster evaporation time\cr $3\times 10^{25}$ & seconds & Galaxy dynamical relaxation timescale\cr $3\times 10^{27}$ & seconds & Earth/Sun orbital gravitational radiation coalescence timescale\cr $1\times 10^{39}$ & seconds & Lower limit on the proton lifetime\cr $4.7\times 10^{73}$ & seconds & 1 M$_\odot$ black hole Hawking evaporation time\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $1.6\times 10^{-35}$ & meters & Planck-Wheeler length$\ = \bigl({G \hbar \over c^3}\bigr)^{1 \over 2}$\cr $2\times 10^{-35}$ & meters & Rough postulated superstring size\cr $1\times 10^{-24}$ & meters & Effective 1 MeV neutrino radius\cr $1.6\times 10^{-22}$ & meters & Radius of a 10 M$_\odot$ star squeezed down to the Planck-Wheeler density\cr $1.5\times 10^{-18}$ & meters & Classical proton radius$\ = {e^2\over 4\pi\epsilon_0 m_{\rm p} c^2}$\cr $1.6\times 10^{-17}$ & meters & $W^\pm$ Compton wavelength$\ = {h\over m_{W^\pm} c}$\ = rough weak force length\cr $4\times 10^{-17}$ & meters & LIGO 4 km gravity-wave detector needed sensitivity\cr $1.3\times 10^{-15}$ & meters & Proton Compton wavelength$\ = {h\over m_{\rm p} c}$\ = rough proton fuzziness length\cr $1.44\times 10^{-15} A^{1\over 3}$ & meters & Nuclear radius\cr $2.8\times 10^{-15}$ & meters & Classical electron radius$\ = {e^2\over 4\pi\epsilon_0 m_{\rm e} c^2}$\cr $8.8\times 10^{-15}$ & meters & $\pi$-meson Compton wavelength$\ = {h\over m_\pi c}$\ = attractive strong force length\cr $1.2\times 10^{-12}$ & meters & 1 MeV $\gamma$-ray wavelength\cr $2.4\times 10^{-12}$ & meters & Electron Compton wavelength$\ = {h\over m_{\rm e} c}$\ = rough electron fuzziness length\cr $5.3\times 10^{-11}$ & meters & Bohr radius$\ = {h^2 \epsilon_0\over \pi m_{\rm e} e^2}$\cr $2.6\times 10^{-10}$ & meters & Copper atom spacing in solid copper\cr $3.5\times 10^{-10}$ & meters & H$_2$O molecular diameter\cr $4\times 10^{-10}$ & meters & ROSAT X-ray satellite mirror rms surface error\cr $1.2\times 10^{-9}$ & meters & 1 keV X-ray wavelength\cr $3\times 10^{-9}$ & meters & Typical mean nucleon spacing during primordial nucleosynthesis\cr $3.4\times 10^{-9}$ & meters & DNA double helix turn length\cr $6\times 10^{-8}$ & meters & Typical rms surface error of a Keck telescope mirror\cr $7.0\times 10^{-8}$ & meters & Molecular mean free path in the atmosphere\cr $1\times 10^{-7}$ & meters & Typical size of a virus\cr $3\times 10^{-7}$ & meters & Interstellar dust grain size\cr $5\times 10^{-7}$ & meters & Optical photon wavelength\cr $4\times 10^{-6}$ & meters & Typical size of a cell\cr $2\times 10^{-4}$ & meters & Small dust particle size\cr $0.03$ & meters & Lunar laser ranging accuracy ({\it Science} 265, 482)\cr $0.068$ & meters & Unraveled human DNA strand length\cr $1.8$ & meters & Man\cr $30$ & meters & Blue Whale\cr $3\, 700$ & meters & Mean ocean depth\cr $4\, 000$ & meters & Error in our knowledge of the distance to Jupiter\cr $5\, 500$ & meters & Rough radius of Halley's comet\cr $8\, 847$ & meters & Height of Mount Everest\cr $10\, 000$ & meters & Neutron star radius\cr $10\, 000$ & meters & Typical asteroid radius\cr $10\, 000$ & meters & Typical comet radius\cr $11\, 032$ & meters & Depth of the Mariana Trench\cr $12\, 000$ & meters & Height of troposphere\cr $12\, 000$ & meters & Typical airliner cruising altitute\cr $30\, 000$ & meters & Typical thickness of the Earth's crust\cr $5.5\times 10^{5}$ & meters & Height of the ASCA X-ray satellite orbit\cr $9\times 10^{5}$ & meters & Height of the COBE satellite orbit\cr $3.2\times 10^{6}$ & meters & Length of the Great Wall of China\cr $6.3\times 10^{6}$ & meters & Radius of the Earth\cr $4.2\times 10^{7}$ & meters & Geostationary satellite orbit height\cr $7.1\times 10^{7}$ & meters & Radius of Jupiter\cr $9\times 10^{7}$ & meters & Distance to the Earth's solar wind bow shock\cr $3.8\times 10^{8}$ & meters & Distance to the Moon\cr $7.0\times 10^{8}$ & meters & Radius of the Sun\cr $1\times 10^{9}$ & meters & Typical X-ray binary accretion disk circularization radius\cr $1.7\times 10^{9}$ & meters & 5 M$_\odot$ star main sequence radius\cr $7\times 10^{9}$ & meters & Typical standoff radius of Jupiter's solar wind bow shock\cr $1.47\times 10^{11}$ & meters & Event horizon radius for a $10^8$ M$_\odot$ maximally rotating Kerr black hole\cr $1.50\times 10^{11}$ & meters & Earth/Sun mean distance\cr $1.5\times 10^{11}$ & meters & Radius of the red giant Mira at minimum light\cr $3\times 10^{11}$ & meters & Radius of the red giant Mira at maximum light\cr $5\times 10^{11}$ & meters & Radius of the 20 M$_\odot$ red supergiant Betelgeuse at maximum light\cr $5.91\times 10^{12}$ & meters & Pluto/Sun mean distance\cr $1.5\times 10^{13}$ & meters & Expected distance to the solar wind termination shock\cr $2\times 10^{14}$ & meters & Rough stellar separation in the central parsec of the Milky Way\cr $4\times 10^{14}$ & meters & Rough stellar separation in a globular cluster\cr $4\times 10^{14}$ & meters & Seyfert galaxy characteristic broad line region radius\cr $2\times 10^{15}$ & meters & Rough Oort Cloud/Sun distance\cr $9.46\times 10^{15}$ & meters & 1 light-year\cr $3.08\times 10^{16}$ & meters & 1 parsec\cr $4\times 10^{16}$ & meters & Nearest nonsolar star to Earth\cr $4.5\times 10^{16}$ & meters & Rough Crab Nebula radius\cr $1.6\times 10^{17}$ & meters & Stromgren sphere radius for an O5 star\cr $3\times 10^{17}$ & meters & Rough Cir X-1 radio nebula radius\cr $3\times 10^{17}$ & meters & Rough supernova biological extinction distance (PASP 106, 689)\cr $5\times 10^{17}$ & meters & Typical interstellar medium cloud size\cr $1.4\times 10^{18}$ & meters & Hyades open cluster distance\cr $1.5\times 10^{18}$ & meters & Trigonometric parallax distance determination limit\cr $1.5\times 10^{18}$ & meters & Typical globular cluster radius\cr $2\times 10^{18}$ & meters & Rough radius of the local interstellar hot gas bubble\cr $2\times 10^{18}$ & meters & Largest dimension of W50 (ARAA 22, 524)\cr $2.6\times 10^{18}$ & meters & Rough distance to PSR J$0108-1431$\cr $5\times 10^{18}$ & meters & Scale height of the Milky Way interstellar medium\cr $5\times 10^{18}$ & meters & Seyfert galaxy characteristic narrow line region radius\cr $5.2\times 10^{18}$ & meters & Distance to the 20 M$_\odot$ red supergiant Betelgeuse (will go supernova within $10\, 000$ years)\cr $2\times 10^{19}$ & meters & Characteristic height of the Milky Way main disk\cr $6\times 10^{19}$ & meters & Typical dwarf galaxy radius\cr $6.6\times 10^{19}$ & meters & Distance to the Crab Nebula\cr $2\times 10^{20}$ & meters & Estimated distance to Cir X-1\cr $2.4\times 10^{20}$ & meters & Distance from Sun to galactic center\cr $1.5\times 10^{21}$ & meters & Distance to the LMC\cr $2\times 10^{21}$ & meters & Rough Milky Way dark matter halo radius\cr $6\times 10^{21}$ & meters & Typical Ly-$\alpha$ galaxy neutral hydrogen radius\cr $1\times 10^{22}$ & meters & Typical active galaxy jet length\cr $1\times 10^{22}$ & meters & Length of the ``superantennae'' of IRAS 19254--7245\cr $1.9\times 10^{22}$ & meters & Distance to M31\cr $3\times 10^{22}$ & meters & Radius of the core of the Virgo cluster of galaxies\cr $4\times 10^{22}$ & meters & Rough Local Group radius\cr $9.2\times 10^{22}$ & meters & Cepheid variable distance determination limit (via ground observations)\cr $1.2\times 10^{23}$ & meters & Distance to the Circinus galaxy\cr $5\times 10^{23}$ & meters & Rough boundary between the nonlinear and linear gravitational collapse regimes\cr $7\times 10^{23}$ & meters & Distance to the $z=0.0036$ Seyfert 2 NGC 1068\cr $7\times 10^{23}$ & meters & Distance to the center of the Virgo cluster of galaxies\cr $9\times 10^{23}$ & meters & Characteristic maximum travel length of a yocto-eV cosmic ray due to pion\cr & & production off the microwave background\cr $2.3\times 10^{24}$ & meters & Shapley supercluster radius\cr $3\times 10^{24}$ & meters & Typical length scale probed by the Harvard/Smithsonian CfA redshift survey\cr $4.1\times 10^{24}$ & meters & Luminosity distance to the $z=0.022$ Coma cluster of galaxies\cr $1.5\times 10^{25}$ & meters & Typical length scale probed by the Lick survey\cr $3.0\times 10^{25}$ & meters & Luminosity distance to the $z=0.158$ quasar 3C273\cr $3\times 10^{25}$ & meters & Typical length scale probed by the 4C radio galaxy survey\cr $3\times 10^{25}$ & meters & Schwarzschild radius of a singularity with the mass of a critical density universe\cr $5.5\times 10^{26}$ & meters & Luminosity distance to the $z=2.286$ ultraluminous IRAS galaxy IRAS F10214+4724\cr $1.3\times 10^{27}$ & meters & Luminosity distance to the $z=4.897$ quasar PC 1247+3406\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $1\times 10^{-9}$ & m s$^{-1}$ & Sea floor spreading rate\cr $1.6\times 10^{-9}$ & m s$^{-1}$ & Average slip rate of the San Andreas fault\cr $1\times 10^{-8}$ & m s$^{-1}$ & Typical rainfall rate in a semi-arid climate\cr $2\times 10^{-8}$ & m s$^{-1}$ & Grass growth rate\cr $3\times 10^{-6}$ & m s$^{-1}$ & Typical glacial advance rate\cr $1\times 10^{-3}$ & m s$^{-1}$ & Equivalent radial velocity resolution of pulsar pulse arrival time analysis\cr $1.3$ & m s$^{-1}$ & Human walking speed\cr $3$ & m s$^{-1}$ & Radial velocity accuracy of high precision Doppler spectroscopy\cr $13$ & m s$^{-1}$ & Speed of the reflex motion induced on the Sun by Jupiter\cr $25$ & m s$^{-1}$ & Car speed\cr $60$ & m s$^{-1}$ & Radial velocity semiamplitude of 51 Pegasi due to its planet\cr $100$ & m s$^{-1}$ & Typical speed of an electric pulse in the nervous system\cr $330$ & m s$^{-1}$ & Sound speed in air\cr $480$ & m s$^{-1}$ & Earth's atmosphere molecular rms velocity\cr $600$ & m s$^{-1}$ & Fighter jet speed\cr $2\, 380$ & m s$^{-1}$ & Escape velocity from Moon's surface\cr $10\, 000$ & m s$^{-1}$ & Typical longitudinal seismic wave velocity in the Earth's mantle\cr $11\, 000$ & m s$^{-1}$ & Escape velocity from the Earth's surface\cr $20\, 000$ & m s$^{-1}$ & Globular cluster stellar velocity dispersion\cr $29\, 000$ & m s$^{-1}$ & Earth's motion around the Sun\cr $40\, 000$ & m s$^{-1}$ & Globular cluster stellar escape velocity\cr $1\times 10^{5}$ & m s$^{-1}$ & Typical Galactic pulsar vertical velocity component\cr $1\times 10^{5}$ & m s$^{-1}$ & Average speed of the initial stroke of a lightning flash\cr $2.2\times 10^{5}$ & m s$^{-1}$ & Rotational velocity of the Sun around the Milky Way's center\cr $3\times 10^{5}$ & m s$^{-1}$ & Orbital speed of PSR 1913+16\cr $3\times 10^{5}$ & m s$^{-1}$ & Rough velocity of Geminga's proper motion\cr $3.65\times 10^{5}$ & m s$^{-1}$ & Motion of the solar system barycenter relative to the cosmic microwave background\cr $4.1\times 10^{5}$ & m s$^{-1}$ & Orbital speed of Cen X-3\cr $6.2\times 10^{5}$ & m s$^{-1}$ & Escape velocity from the Sun's surface\cr $6.2\times 10^{5}$ & m s$^{-1}$ & Escape velocity from the Milky Way for objects in the solar neighborhood (ARAA 29, 429)\cr $6.22\times 10^{5}$ & m s$^{-1}$ & Motion of the Local Group relative to the cosmic microwave background\cr $8\times 10^{5}$ & m s$^{-1}$ & Typical galaxy cluster galaxy velocity dispersion\cr $2\times 10^{6}$ & m s$^{-1}$ & Speed of $n=1$ hydrogen electron = $Z\alpha c$\cr $5\times 10^{6}$ & m s$^{-1}$ & Young (months old) supernova ejecta\cr $1.2\times 10^{7}$ & m s$^{-1}$ & Velocity of the wind streaming out from H1413+117 ``Cloverleaf'' ({\it Nature\/} 371, 559)\cr $7.8\times 10^{7}$ & m s$^{-1}$ & SS433 jet speed\cr $1.4\times 10^{8}$ & m s$^{-1}$ & Keplerian orbital velocity at the surface of a neutron star\cr $2\times 10^{8}$ & m s$^{-1}$ & Escape velocity from neutron star surface\cr $2.8\times 10^{8}$ & m s$^{-1}$ & Ejecta from GRS 1915+105 ({\it Nature\/} 371, 46)\cr $2.998\times 10^{8}$ & m s$^{-1}$ & Light in a vacuum\cr $3.7\times 10^{8}$ & m s$^{-1}$ & Apparent superluminal motion of the ejecta from GRS 1915+105 ({\it Nature\/} 371, 46)\cr $6\times 10^{9}$ & m s$^{-1}$ & Apparent superluminal motion of the jet from the $z=2.16$ quasar 0836+710\cr $2.7\times 10^{10}$ & m s$^{-1}$ & Apparent superluminal motion of the jet from the $z=0.940$ BL Lac AO 0235+164 (may be lensed)\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $4.2\times 10^{-36}$ & kilograms & Mass equivalent of a green light photon\cr $9.1\times 10^{-36}$ & kilograms & Electron antineutrino upper mass limit\cr $4.8\times 10^{-31}$ & kilograms & Muon neutrino upper mass limit\cr $9.11\times 10^{-31}$ & kilograms & Electron mass\cr $5.5\times 10^{-29}$ & kilograms & Tau neutrino upper mass limit\cr $1.67\times 10^{-27}$ & kilograms & Proton mass\cr $9\times 10^{-27}$ & kilograms & Bottom quark mass\cr $4.8\times 10^{-26}$ & kilograms & Mean mass of atmosphere molecule\cr $1.4\times 10^{-25}$ & kilograms & $W^\pm$ mass ($80.22\pm 0.22$ GeV/$c^2$)\cr $1.6\times 10^{-25}$ & kilograms & $Z^0$ mass ($91.187\pm 0.007 $ GeV/$c^2$)\cr $2\times 10^{-25}$ & kilograms & Favored Higgs boson mass\cr $3.1\times 10^{-25}$ & kilograms & Top quark mass ($176\pm 13$ GeV/$c^2$)\cr $4\times 10^{-25}$ & kilograms & DNA nucleotide\cr $1\times 10^{-22}$ & kilograms & Typical protein molecule mass\cr $5\times 10^{-21}$ & kilograms & {\it E. Coli\/} ribosome\cr $1\times 10^{-16}$ & kilograms & Interstellar dust grain mass\cr $8\times 10^{-15}$ & kilograms & Rough mass of a human DNA molecule\cr $7\times 10^{-13}$ & kilograms & Typical mass of a cell\cr $2.2\times 10^{-8}$ & kilograms & Planck-Wheeler mass$\ = \bigl({\hbar c\over G}\bigr)^{1 \over 2}$\cr $1\times 10^{-5}$ & kilograms & Typical mosquito mass\cr $0.02$ & kilograms & Typical goldfish mass\cr $70$ & kilograms & Typical human mass\cr $70$ & kilograms & Lower limit to the allowed mass for a Sumo wrestler\cr $100$ & kilograms & Meteorite mass before entry into Earth's atmosphere\cr $420$ & kilograms & ASCA X-ray satellite mass\cr $900$ & kilograms & Compton {\it Gamma-Ray Observatory\/} satellite mass\cr $1\, 000$ & kilograms & Car\cr $2\, 200$ & kilograms & ISO infrared satellite mass at launch\cr $10\, 000$ & kilograms & Tyrannosaurus Rex\cr $5\times 10^{11}$ & kilograms & Initial mass of a primordial black hole with evaporation time equal to the universe's age\cr $1\times 10^{13}$ & kilograms & Typical comet mass\cr $3\times 10^{14}$ & kilograms & Typical mountain mass\cr $1.1\times 10^{16}$ & kilograms & Superterranean biomass of Earth (ocean organisms are included)\cr $5.3\times 10^{18}$ & kilograms & Total mass of Earth's atmosphere\cr $3\times 10^{19}$ & kilograms & Typical asteroid mass\cr $1.4\times 10^{21}$ & kilograms & Total mass of Earth's oceans\cr $4.8\times 10^{22}$ & kilograms & Mass of Europa\cr $7.3\times 10^{22}$ & kilograms & Mass of the Moon\cr $2\times 10^{24}$ & kilograms & Rough Oort cloud mass\cr $5.98\times 10^{24}$ & kilograms & Mass of the Earth\cr $1.9\times 10^{27}$ & kilograms & Mass of Jupiter\cr $1.6\times 10^{29}$ & kilograms & Minimum mass to fusion burn hydrogen\cr $4\times 10^{29}$ & kilograms & Rough mass of MACHO and EROS microlensing objects\cr $1.99\times 10^{30}$ & kilograms & Mass of the Sun\cr $2.8\times 10^{30}$ & kilograms & Chandrasekhar mass (maximum mass for a white dwarf)\cr $6.0\times 10^{30}$ & kilograms & Oppenheimer-Volkoff mass (maximum mass for a neutron star)\cr $1.2\times 10^{31}$ & kilograms & Minimum mass of the unseen object in GS2023+338/V404 Cygni\cr $4\times 10^{31}$ & kilograms & Rough stellar mass above which the evolutionary endpoint is a black hole\cr $1.0\times 10^{32}$ & kilograms & Mass of the most massive member of Plaskett's star\cr $1.2\times 10^{32}$ & kilograms & Rough mass at which a star becomes unstable to pulsations\cr $2\times 10^{33}$ & kilograms & Typical interstellar cloud mass\cr $1\times 10^{36}$ & kilograms & Typical mass of a globular cluster\cr $5\times 10^{36}$ & kilograms & Approximate mass of the Milky Way central black hole\cr $1\times 10^{37}$ & kilograms & Rough baryonic Jeans mass immediately after decoupling\cr $4\times 10^{39}$ & kilograms & Rough mass of the SMC\cr $2\times 10^{40}$ & kilograms & Rough mass of the LMC\cr $2.6\times 10^{42}$ & kilograms & Rough mass of the visible and dark matter in the Milky Way (ApJ 345, 759)\cr $1.3\times 10^{44}$ & kilograms & Rough mass of the stars in the Coma galaxy cluster\cr $6.4\times 10^{44}$ & kilograms & Rough mass of the X-ray gas in the Coma galaxy cluster\cr $2.7\times 10^{45}$ & kilograms & Rough virial mass of the Coma galaxy cluster\cr $6\times 10^{45}$ & kilograms & Rough virial mass of the Abell 2163 galaxy cluster\cr $2\times 10^{48}$ & kilograms & Rough baryonic Jeans mass immediately before decoupling\cr $1.4\times 10^{49}$ & kilograms & Rough total mass in spiral galaxies\cr $2\times 10^{49}$ & kilograms & Rough total (baryonic and nonbaryonic) mass in galaxy clusters\cr $3\times 10^{49}$ & kilograms & Rough total mass in elliptical and spheroidal galaxies\cr $8\times 10^{49}$ & kilograms & Rough total mass of visible matter in the universe\cr $1\times 10^{51}$ & kilograms & Rough total baryon mass predicted by primordial nucleosynthesis\cr $2\times 10^{52}$ & kilograms & Rough total mass of a critical density universe\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $2\times 10^{-38}$ & kg m$^{-3}$ & Effective density of the 100-300 MHz radio background\cr $1\times 10^{-35}$ & kg m$^{-3}$ & Effective density of the 1--10 MeV $\gamma$-ray background\cr $8\times 10^{-35}$ & kg m$^{-3}$ & Effective density of the 2--100 keV X-ray background\cr $1.1\times 10^{-33}$ & kg m$^{-3}$ & Upper limit to the effective density of the gravitational wave background\cr $1\times 10^{-32}$ & kg m$^{-3}$ & Effective density of the starlight released in a Hubble time\cr $4.6\times 10^{-31}$ & kg m$^{-3}$ & Effective density of the cosmic microwave background radiation\cr $2\times 10^{-29}$ & kg m$^{-3}$ & Smoothed density of visible galactic material throughout universe\cr $2\times 10^{-28}$ & kg m$^{-3}$ & Smoothed baryon density predicted by primordial nucleosynthesis\cr $4.7\times 10^{-27}$ & kg m$^{-3}$ & Critical density of the universe $= {3 H_0^2\over 8 \pi G}$\cr $2\times 10^{-24}$ & kg m$^{-3}$ & Typical gas in a cluster of galaxies\cr $3\times 10^{-21}$ & kg m$^{-3}$ & Typical gas in the interstellar medium of the Milky Way\cr $7\times 10^{-21}$ & kg m$^{-3}$ & Dynamically inferred Milky Way disk density\cr $5\times 10^{-20}$ & kg m$^{-3}$ & Typical density of the gas in the central kiloparsec of an interacting or starburst galaxy\cr $1\times 10^{-9}$ & kg m$^{-3}$ & Best room temperature vacuum achieved on Earth\cr $1.7\times 10^{-4}$ & kg m$^{-3}$ & Mean density of Antares (19 M$_\odot$)\cr $1.3$ & kg m$^{-3}$ & Density of air\cr $700$ & kg m$^{-3}$ & Mean density of Saturn\cr $1\, 000$ & kg m$^{-3}$ & Density of water\cr $1\, 300$ & kg m$^{-3}$ & Mean density of Jupiter\cr $1\, 400$ & kg m$^{-3}$ & Mean density of the Sun\cr $3\, 300$ & kg m$^{-3}$ & Mean density of the Moon\cr $5\, 500$ & kg m$^{-3}$ & Mean density of the Earth\cr $7\, 860$ & kg m$^{-3}$ & Density of iron\cr $19\, 300$ & kg m$^{-3}$ & Density of gold\cr $5\times 10^{7}$ & kg m$^{-3}$ & Typical white dwarf mean density\cr $3\times 10^{10}$ & kg m$^{-3}$ & Typical white dwarf central density\cr $1.1\times 10^{12}$ & kg m$^{-3}$ & Inverse $\beta$ decay threshold\cr $4.3\times 10^{14}$ & kg m$^{-3}$ & Neutron drip density\cr $6\times 10^{17}$ & kg m$^{-3}$ & Nuclear density\cr $1\times 10^{18}$ & kg m$^{-3}$ & Typical neutron star central density\cr $5\times 10^{96}$ & kg m$^{-3}$ & Planck-Wheeler density, at which quantum gravitational effects become important$\ = {c^5\over G^2 \hbar}$\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $6\times 10^{-25}$ & joules & Lamb-Retherford shift\cr $9.5\times 10^{-25}$ & joules & 21.049 cm photon---hyperfine shift\cr $4\times 10^{-22}$ & joules & Molecular rotation transition\cr $4\times 10^{-21}$ & joules & $kT_{\rm room}$\ = translational kinetic energy of atmosphere gas molecule\cr $7\times 10^{-21}$ & joules & Donor level/conduction band gap in a doped semiconductor\cr $3\times 10^{-20}$ & joules & Molecular vibration transition\cr $1.6\times 10^{-19}$ & joules & Valence band/conduction band gap in a semiconductor\cr $2.2\times 10^{-19}$ & joules & Bond energy of an organic substance with half-life $30\, 000$ years\cr $3.8\times 10^{-19}$ & joules & Green light photon\cr $9\times 10^{-19}$ & joules & Valence band/conduction band gap in an insulator\cr $1.1\times 10^{-18}$ & joules & Fermi energy in copper = depth of Fermi sea\cr $1.1\times 10^{-18}$ & joules & Positronium ionization energy\cr $2.2\times 10^{-18}$ & joules & Hydrogen $n=1$ binding energy\cr $1.6\times 10^{-16}$ & joules & 1 keV X-ray\cr $1.5\times 10^{-15}$ & joules & Hydrogenic iron $n=1$ binding energy\cr $8.18\times 10^{-14}$ & joules & Electron rest mass\cr $1.6\times 10^{-13}$ & joules & 1 MeV $\gamma$-ray\cr $1.6\times 10^{-13}\ (Z_1 \times Z_2)$ & joules & Coulomb barrier height\cr $1.3\times 10^{-12}$ & joules & Nucleon binding energy\cr $4.3\times 10^{-12}$ & joules & Energy from $4\times(^1$H$)\rightarrow\ ^4$He\cr $1.50\times 10^{-10}$ & joules & Proton rest mass\cr $1.6\times 10^{-7}$ & joules & Particle kinetic energy in a 1 TeV accelerator\cr $10$ & joules & Well hit tennis ball\cr $51$ & joules & Fly's Eye most energetic cosmic ray event\cr $2\times 10^{5}$ & joules & Energy from a light bulb burning for 1 hour\cr $2\times 10^{7}$ & joules & Rough energy from a 1 kilogram meal\cr $4.2\times 10^{9}$ & joules & Explosion energy of 1 ton of TNT\cr $2\times 10^{10}$ & joules & Rough energy of a lightning flash\cr $2\times 10^{11}$ & joules & Rough human total energy output in a lifetime\cr $1.5\times 10^{14}$ & joules & Typical atomic bomb explosion energy\cr $6\times 10^{16}$ & joules & Tunguska 50 m diameter meteorite impact energy\cr $1\times 10^{17}$ & joules & Powerful H-bomb explosion energy\cr $3\times 10^{17}$ & joules & Elastic wave energy release from a large $(M=8.5)$ earthquake\cr $5\times 10^{17}$ & joules & Explosion energy of Krakatoa\cr $3\times 10^{18}$ & joules & Superman flying at 70 per cent of light speed\cr $9\times 10^{18}$ & joules & USA electricity usage in 1986\cr $5\times 10^{19}$ & joules & Rough explosion energy of the Lake Toba eruption in Sumatra\cr $2.5\times 10^{22}$ & joules & Energy from the comet Shoemaker-Levy 9 fragment G impact on Jupiter\cr $4\times 10^{23}$ & joules & K-T 10 km diameter meteorite impact energy\cr $1\times 10^{24}$ & joules & Power released by an evaporating black hole during the last second of its life\cr $2.1\times 10^{29}$ & joules & The Earth's rotational energy\cr $3\times 10^{31}$ & joules & The Earth's total heat content\cr $7\times 10^{34}$ & joules & Total rotational energy of the planets\cr $2.5\times 10^{35}$ & joules & Rotational energy of the Sun\cr $3\times 10^{36}$ & joules & Gravitational internal binding energy of Jupiter\cr $6\times 10^{37}$ & joules & Nova Persei outburst\cr $3\times 10^{41}$ & joules & A 450 km s$^{-1}$ neutron star kick\cr $3\times 10^{43}$ & joules & Energy needed to make the local bubble\cr $1.3\times 10^{44}$ & joules & Total radiant energy from the Sun --- $({1\over 10})(0.007)$M$_\odot c^2$\cr $3\times 10^{44}$ & joules & Energy in photons from a type II supernova explosion\cr $1\times 10^{45}$ & joules & Rough total energy from a cosmological $\gamma$-ray burst\cr $3\times 10^{46}$ & joules & Energy in neutrinos from a type II supernova explosion\cr $2\times 10^{53}$ & joules & Typical gravitational binding energy of a galaxy\cr $2\times 10^{54}$ & joules & Typical magnetic and kinetic energy in a large radio lobe (Shu 311)\cr $5.2\times 10^{54}$ & joules & Rotational energy of a $10^8$ M$_\odot$ maximal Kerr black hole $=0.29$M$_\bullet$$c^2$\cr $5\times 10^{57}$ & joules & Typical gravitational binding energy of a cluster of galaxies\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $2\times 10^{7}$ & J kg$^{-1}$ & Efficiency of the metabolism of food\cr $1.3\times 10^{13}$ & J kg$^{-1}$ & Efficiency of dropping matter onto a white dwarf\cr $6.3\times 10^{14}$ & J kg$^{-1}$ & Efficiency of fusion burning hydrogen\cr $5.1\times 10^{15}$ & J kg$^{-1}$ & Slowly spiraling accretion onto a Schwarzschild black hole\cr $7.5\times 10^{15}$ & J kg$^{-1}$ & Shakura-Sunyaev efficiency for accretion onto a Newtonian ``black hole''\cr $8\times 10^{15}$ & J kg$^{-1}$ & Efficiency of dropping matter onto a neutron star\cr $2.6\times 10^{16}$ & J kg$^{-1}$ & Slowly spiraling prograde accretion onto a realistically maximally rotating Kerr black hole\cr $3.8\times 10^{16}$ & J kg$^{-1}$ & Slowly spiraling prograde accretion onto a theoretically maximally rotating Kerr black hole\cr $8.99\times 10^{16}$ & J kg$^{-1}$ & Efficiency of matter-antimatter annihilation\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $4\times 10^{-6}$ & watts & Average energy output from 1 kilogram of the Milky Way\cr $1\times 10^{-3}$ & watts & Optical disc player laser\cr $6$ & watts & Amateur short wave radio transmitter\cr $60$ & watts & Light bulb\cr $100$ & watts & Gravitational wave power from the Earth-Sun system\cr $150$ & watts & Human being under normal conditions\cr $750$ & watts & Maximum long duration horse output\cr $1\, 500$ & watts & Typical fireplace fire\cr $20\, 000$ & watts & Car\cr $7\times 10^{4}$ & watts & Soft X-ray scattered lunar luminosity\cr $1\times 10^{5}$ & watts & Running Tyrannosaurus Rex\cr $3\times 10^{8}$ & watts & Nuclear power reactor\cr $3\times 10^{8}$ & watts & Moderate thunderstorm electrical power generation rate\cr $1.3\times 10^{9}$ & watts & Hoover dam\cr $4\times 10^{9}$ & watts & Soft X-ray Jovian auroral luminosity\cr $3\times 10^{11}$ & watts & USA average electricity usage rate in 1986\cr $1\times 10^{13}$ & watts & Solar radio luminosity\cr $8\times 10^{13}$ & watts & Powerful nanosecond pulse laser\cr $1.7\times 10^{17}$ & watts & Insolation of Earth\cr $1\times 10^{20}$ & watts & X-ray luminosity of the quiet Sun\cr $1\times 10^{23}$ & watts & Typical white dwarf luminosity\cr $8\times 10^{24}$ & watts & Gravitational wave radiation from PSR 1913+16\cr $3.9\times 10^{26}$ & watts & Solar luminosity\cr $5\times 10^{26}$ & watts & The 2--10 keV flux of the cataclysmic variable FO Aquarii\cr $1\times 10^{28}$ & watts & Typical X-ray luminosity of an X-ray pulsar\cr $1\times 10^{28}$ & watts & X-ray luminosity associated with Sgr A$^{\ast}$\cr $3.5\times 10^{28}$ & watts & Rotational energy loss rate from the Geminga pulsar\cr $4.3\times 10^{28}$ & watts & Megamaser in NGC 4258\cr $2.4\times 10^{29}$ & watts & 5 M$_\odot$ star on main sequence\cr $4\times 10^{30}$ & watts & Cygnus X-1 X-ray luminosity\cr $5.5\times 10^{30}$ & watts & Luminosity of the 20 M$_\odot$ red supergiant Betelgeuse at maximum light\cr $1\times 10^{31}$ & watts & Crab Nebula energy output\cr $2\times 10^{31}$ & watts & Eddington limit for a 1.4 M$_\odot$ neutron star\cr $3\times 10^{31}$ & watts & Typical luminosity of Cir X-1 in zero phase\cr $3\times 10^{31}$ & watts & Typical luminosity of GRS 1915+105 in outburst ({\it Nature\/} 371, 46)\cr $1\times 10^{33}$ & watts & Rough luminosity of Eta Carinae in April 1843\cr $5\times 10^{35}$ & watts & Type II supernova peak photon luminosity\cr $3\times 10^{36}$ & watts & Milky Way\cr $1.5\times 10^{38}$ & watts & Coma cluster X-ray gas luminosity\cr $1\times 10^{39}$ & watts & $10^8$ M$_\odot$ black hole accreting at ${1\over 10}$ of the Eddington limit\cr $1\times 10^{39}$ & watts & Typical quasar luminosity\cr $1\times 10^{40}$ & watts & Rough luminosity of the quasar 3C273\cr $2\times 10^{41}$ & watts & Rough luminosity of the $z=2.286$ ultraluminous IRAS galaxy IRAS F10214+4724\cr $6\times 10^{43}$ & watts & Rough luminosity of a cosmological $\gamma$-ray burst\cr $2\times 10^{46}$ & watts & Rough luminosity of all the stars in the universe\cr $1\times 10^{48}$ & watts & Core collapse neutrino luminosity of a type II supernova (QJRAS 30, 423)\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $7\times 10^{-7}$ & kelvins & Laser cooling of cesium atoms\cr $1.3\times 10^{-5}$ & kelvins & Cosmic microwave background quadrupole anisotropy\cr $5\times 10^{-4}$ & kelvins & Typical Sunyaev-Zel'dovich cosmic microwave background decrement\cr $3.3\times 10^{-3}$ & kelvins & Cosmic microwave background dipole anisotropy\cr $0.01$ & kelvins & Typical limit of liquid helium dilution cooling\cr $0.3$ & kelvins & Typical limit of liquid helium evaporation cooling\cr $2.17$ & kelvins & Liquid $^4$He superfluid transition temperature\cr $2.726$ & kelvins & Cosmic microwave background temperature today\cr $3.20$ & kelvins & Liquid $^3$He boiling point\cr $4$ & kelvins & Typical limit of Joule-Thomson effect cooling\cr $4.18$ & kelvins & Liquid $^4$He boiling point\cr $6$ & kelvins & Typical noise temperature of a HEMT receiver at 30 GHz\cr $12$ & kelvins & Lanthanum (under pressure) superconductivity critical temperature (highest for a pure element)\cr $20$ & kelvins & Liquid H$_2$ boiling temperature\cr $77$ & kelvins & Liquid N$_2$ boiling temperature\cr $133$ & kelvins & Mercury-barium-calcium-copper oxide compound superconductivity critical temperature\cr $273$ & kelvins & Water freezing temperature\cr $311$ & kelvins & Human surface temperature\cr $373$ & kelvins & Water boiling temperature\cr $388$ & kelvins & Brimstone melting temperature---upper limit to the temperature of Hell\cr $506$ & kelvins & Paper burning temperature\cr $740$ & kelvins & Typical surface temperature of Venus\cr $1811$ & kelvins & Melting temperature of iron\cr $3000$ & kelvins & Cosmic microwave background temperature at decoupling\cr $5770$ & kelvins & Solar effective temperature\cr $5\times 10^{5}$ & kelvins & Surface temperature of the Geminga pulsar\cr $3\times 10^{6}$ & kelvins & Polar cap temperature of the Geminga pulsar\cr $3\times 10^{6}$ & kelvins & Typical fusion experiment\cr $1.4\times 10^{7}$ & kelvins & Center of the Sun\cr $1.5\times 10^{7}$ & kelvins & Changeover temperature from the proton-proton chain to the CNO cycle\cr $2.7\times 10^{7}$ & kelvins & Center of a 5 M$_\odot$ star\cr $5\times 10^{7}$ & kelvins & Typical gas temperature in a cluster of galaxies\cr $1\times 10^{8}$ & kelvins & Typical cataclysmic variable accretion column shock temperature\cr $4\times 10^{8}$ & kelvins & Characteristic temperature for electron-positron pair production\cr $4\times 10^{8}$ & kelvins & Minimum primordial nucleosynthesis temperature\cr $5\times 10^{8}$ & kelvins & Inner accretion disc temperature of Cyg X-1\cr $7\times 10^{8}$ & kelvins & Thermal electrons become relativistic $(v_{\rm e}={c\over 2})$\cr $1\times 10^{9}$ & kelvins & Maximum primordial nucleosynthesis temperature\cr $1\times 10^{9}$ & kelvins & Rough superconductivity critical temperature in a neutron star\cr $1\times 10^{10}$ & kelvins & Rough plasma pair catastrophe temperature\cr $3\times 10^{10}$ & kelvins & Core collapse temperature of a supernova (QJRAS 30, 424)\cr $3\times 10^{15}$ & kelvins & Rough electroweak unification temperature\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $7\times 10^{-13}$ & N m$^{-2}$ & Typical gas pressure in a cluster of galaxies\cr $5\times 10^{-12}$ & N m$^{-2}$ & Pressure in the best vacuum achieved on Earth\cr $5\times 10^{-6}$ & N m$^{-2}$ & Solar radiation pressure at the Earth\cr $1\times 10^{-5}$ & N m$^{-2}$ & Pressure of a sound wave at the human threshold of hearing\cr $0.2$ & N m$^{-2}$ & Solar radiation pressure at the surface of the Sun\cr $30$ & N m$^{-2}$ & Pressure of a sound wave at the human threshold of pain\cr $1\times 10^{4}$ & N m$^{-2}$ & Mean human arterial blood overpressure\cr $1.5\times 10^{4}$ & N m$^{-2}$ & Standing person\cr $1\times 10^{5}$ & N m$^{-2}$ & Typical atmospheric pressure\cr $1.5\times 10^{6}$ & N m$^{-2}$ & High pressure bicycle tire\cr $2\times 10^{7}$ & N m$^{-2}$ & Typical scuba tank pressure\cr $9\times 10^{7}$ & N m$^{-2}$ & Peak pressure of a fist on concrete during a karate strike\cr $1.1\times 10^{8}$ & N m$^{-2}$ & Pressure at the bottom of the Marianas trench\cr $6\times 10^{9}$ & N m$^{-2}$ & Pressure needed for the natural crystalization of diamonds\cr $1\times 10^{10}$ & N m$^{-2}$ & Conventional high pressure laboratory press\cr $2\times 10^{11}$ & N m$^{-2}$ & Peak pressure from a diamond anvil pressure cell\cr $5\times 10^{11}$ & N m$^{-2}$ & Central pressure of the Earth\cr $4\times 10^{12}$ & N m$^{-2}$ & Central pressure of Jupiter\cr $2\times 10^{13}$ & N m$^{-2}$ & Radiation pressure at the center of the Sun\cr $2.7\times 10^{16}$ & N m$^{-2}$ & Central pressure of the Sun\cr $1\times 10^{23}$ & N m$^{-2}$ & Typical central pressure of a white dwarf\cr $1\times 10^{34}$ & N m$^{-2}$ & Typical central pressure of a neutron star\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $1\times 10^{-12}$ & W m$^{-2}$ & Threshold of hearing (0 dB)\cr $1\times 10^{-11}$ & W m$^{-2}$ & Rustle of leaves (10 dB)\cr $1\times 10^{-10}$ & W m$^{-2}$ & Quiet whisper (20 dB)\cr $1\times 10^{-9}$ & W m$^{-2}$ & Soft music (30 dB)\cr $3\times 10^{-8}$ & W m$^{-2}$ & Average residence (45 dB)\cr $1\times 10^{-6}$ & W m$^{-2}$ & Background music (60 dB)\cr $3\times 10^{-6}$ & W m$^{-2}$ & Ordinary conversation at 0.5 meters (65 dB)\cr $1\times 10^{-5}$ & W m$^{-2}$ & Busy street traffic (70 dB)\cr $3\times 10^{-5}$ & W m$^{-2}$ & Typical factory (75 dB)\cr $1\times 10^{-3}$ & W m$^{-2}$ & Rough boundary of unsafe sound levels (90 dB)\cr $1\times 10^{-2}$ & W m$^{-2}$ & Lawn mower (100 dB)\cr 1 & W m$^{-2}$ & Loud rock music concert (120 dB)\cr 10 & W m$^{-2}$ & Threshold of pain (130 dB)\cr 100 & W m$^{-2}$ & Jet plane at 30 meters (140 dB)\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $9.128\times 10^{-35}$ & kg m$^2$ s$^{-1}$ & Magnitude of the electron spin angular momentum = $\sqrt{3\over 4}\hbar$\cr $1.054\times 10^{-34}$ & kg m$^2$ s$^{-1}$ & Planck angular momentum = $\hbar$\cr $3\times 10^{12}$ & kg m$^2$ s$^{-1}$ & Rough angular momentum of an artificial satellite\cr $5.9\times 10^{33}$ & kg m$^2$ s$^{-1}$ & Earth rotational angular momentum\cr $1.7\times 10^{41}$ & kg m$^2$ s$^{-1}$ & Sun rotational angular momentum\cr $3.1\times 10^{43}$ & kg m$^2$ s$^{-1}$ & Total angular momentum of our solar system\cr $2\times 10^{55}$ & kg m$^2$ s$^{-1}$ & Angular momentum of the Sun around the center of the Milky Way\cr $4\times 10^{66}$ & kg m$^2$ s$^{-1}$ & Rough total angular momentum of the Milky Way\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $1\times 10^{-13}$ & teslas & Spontaneous human brain activity\cr $1\times 10^{-12}$ & teslas & Evoked human brain activity\cr $1\times 10^{-12}$ & teslas & Typical magnetic field needed for good radio reception \cr $1\times 10^{-11}$ & teslas & Typical magnetic field from a human heart\cr $1\times 10^{-10}$ & teslas & Typical 50/60 Hz magnetic field inside a building\cr $5\times 10^{-10}$ & teslas & Typical magnetic field strength in the local interstellar medium\cr $1\times 10^{-9}$ & teslas & Typical magnetic field strength in a radio lobe\cr $1\times 10^{-8}$ & teslas & Typical magnetic field strength in the central 300 parsecs of the Milky Way\cr $5\times 10^{-8}$ & teslas & Magnetic field in the Crab Nebula\cr $1\times 10^{-7}$ & teslas & Magnetic field in The Arc at the Milky Way center\cr $1\times 10^{-6}$ & teslas & Typical magnetic field from a hand held cordless phone\cr $3\times 10^{-5}$ & teslas & Magnetic field at Earth's surface\cr $1\times 10^{-4}$ & teslas & Magnetic field near Sun's pole\cr $4\times 10^{-4}$ & teslas & Magnetic field at Jupiter's cloud tops\cr $0.1$ & teslas & Ap star magnetic field\cr $0.2$ & teslas & Sunspot magnetic field\cr $1$ & teslas & Typical medical NMR magnetic field\cr $2$ & teslas & Magnetic field felt by the electron in an $n=1$ hydrogen atom\cr $2$ & teslas & RS CVn star spot magnetic field\cr $12$ & teslas & Typical magnetic field used in high resolution NMR spectroscopy\cr $25$ & teslas & Powerful superconducting/normal hybrid magnet\cr $1\times 10^{8}$ & teslas & Typical single pulsar dipole magnetic field strength\cr $4.4\times 10^{9}$ & teslas & Magnetic field strength when the energy of the first electron Landau level is\cr & & comparable to the electron rest mass (MNRAS 275, 257)\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $1\times 10^{4}$ & amperes & Peak lightning bolt current\cr $5\times 10^{6}$ & amperes & Current along Io's flux tube ({\it Science\/} 262, 1035)\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $3\times 10^{8}$ & volts & Typical potential difference across a lightning bolt\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $3\times 10^{6}$ & V m$^{-1}$ & Electrical discharge field in air with ions\cr $1\times 10^{12}$ & V m$^{-1}$ & Typical electric field at the surface of a pulsar\cr $1\times 10^{19}$ & V m$^{-1}$ & QED pair production electric field limit\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $240$ & bits & Eigen replicator genome --- 120 nucleotides\cr $440$ & bits & Spiegelman monster genome --- 220 nucleotides\cr $9\, 000$ & bits & $Q_\beta$ virus genome --- $4\, 500$ nucleotides\cr $32\, 000$ & bits & Single spaced typed page\cr $6.6\times 10^{5}$ & bits & Uncompressed ASCII version of {\it Lysistrata}\cr $4.36\times 10^{6}$ & bits & {\it C. elegans\/} nematode chromosome III --- longest contiguous piece of DNA sequenced\cr $6\times 10^{6}$ & bits & {\it E. Coli\/} genome --- 3 million nucleotides\cr $6.3\times 10^{6}$ & bits & Uncompressed ASCII version of {\it A Tale of Two Cities}\cr $2.6\times 10^{7}$ & bits & Yeast genome --- 13 million nucleotides\cr $3.6\times 10^{7}$ & bits & Uncompressed ASCII version of {\it The Bible}\cr $2\times 10^{8}$ & bits & Nematode genome --- 100 million nucleotides\cr $1\times 10^{9}$ & bits & Microcomputer hard drive\cr $2.5\times 10^{9}$ & bits & Twenty volume edition of the Oxford English Dictionary on CD-ROM\cr $7\times 10^{9}$ & bits & MACHO project data intake per night\cr $9\times 10^{9}$ & bits & Human genome\cr $8\times 10^{10}$ & bits & Sloan Digital Sky Survey spectral database\cr $1.4\times 10^{11}$ & bits & Cambridge X-ray group total disk space\cr $2\times 10^{11}$ & bits & International Halley watch database\cr $5\times 10^{11}$ & bits & VCR tape\cr $1\times 10^{12}$ & bits & Speed reading for 80 years with perfect memory\cr $8.8\times 10^{12}$ & bits & HST archive size in mid-1994\cr $9\times 10^{12}$ & bits & VLA {\it FIRST\/} Survey data set\cr $2\times 10^{13}$ & bits & Digitized new Palomar sky survey\cr $5\times 10^{13}$ & bits & Sloan Digital Sky Survey 0.4 arcsecond pixel map\cr $8\times 10^{13}$ & bits & NSF backbone traffic in March 1994\cr $3\times 10^{16}$ & bits & HDTV for 80 years with perfect memory\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $200$ & bits s$^{-1}$ & Typical reading and talking rate\cr $500$ & bits s$^{-1}$ & Fast speed reading rate\cr $24\, 000$ & bits s$^{-1}$ & {\it Hipparcos\/} satellite data acquisition rate\cr $56\, 000$ & bits s$^{-1}$ & Typical Internet link\cr $1\times 10^{5}$ & bits s$^{-1}$ & High quality audio\cr $1.4\times 10^{5}$ & bits s$^{-1}$ & HST archive mean growth rate\cr $1\times 10^{7}$ & bits s$^{-1}$ & Xerox Ethernet\cr $1\times 10^{7}$ & bits s$^{-1}$ & HDTV bit rate after compression\cr $4.5\times 10^{7}$ & bits s$^{-1}$ & Internet backbone T3 link\cr $6\times 10^{7}$ & bits s$^{-1}$ & Sloan Digital Sky Survey data acquisition rate\cr $3\times 10^{10}$ & bits s$^{-1}$ & Soliton optical fiber information transmission rate\cr $2\times 10^{15}$ & bits s$^{-1}$ & Sexual reproduction genetic information transmission rate\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $2\, 100$ & 1994 USA dollars & Average USA public school spending per pupil in 1960\cr $6\, 200$ & 1994 USA dollars & Average USA public school spending per pupil in 1993\cr $2\times 10^{5}$ & 1994 USA dollars & Vancouver liquid mercury mirror telescope\cr $9\times 10^{6}$ & 1994 USA dollars & Income of St. John's College, Cambridge during 1992--1993\cr $1.5\times 10^{7}$ & 1994 USA dollars & Development and construction cost of the Giant Meterwave Radio Telescope near\cr & & Pune, India\cr $2.9\times 10^{7}$ & 1994 USA dollars & Total predicted cost of the Sloan Digital Sky Survey\cr $3\times 10^{7}$ & 1994 USA dollars & Rough United States ACLU yearly national operations budget\cr $3\times 10^{7}$ & 1994 USA dollars & Rough United States NRA lobbying budget\cr $5.5\times 10^{7}$ & 1994 USA dollars & Development, construction, and launch cost of the {\it Clementine I\/} spacecraft\cr $8.5\times 10^{7}$ & 1994 USA dollars & VLBA development and construction cost\cr $9\times 10^{7}$ & 1994 USA dollars & Development and construction cost of the Keck telescope\cr $1\times 10^{8}$ & 1994 USA dollars & Development and construction cost of the ASCA X-ray satellite\cr $1.5\times 10^{8}$ & 1994 USA dollars & Typical holdings of an old wealthy Oxbridge college\cr $1.5\times 10^{8}$ & 1994 USA dollars & Rough cost of a European Ariane rocket launch\cr $2\times 10^{8}$ & 1994 USA dollars & Development and construction cost of the VLA\cr $2.1\times 10^{8}$ & 1994 USA dollars & Total spending in the 1994 United States senate election campaigns\cr $3.7\times 10^{8}$ & 1994 USA dollars & Rough construction and operation cost (for 4 years) of LIGO\cr $7.8\times 10^{8}$ & 1994 USA dollars & Rough United States NEA revenues\cr $9\times 10^{8}$ & 1994 USA dollars & Development, construction, and launch cost of the {\it Magellan\/} probe\cr $9.8\times 10^{8}$ & 1994 USA dollars & Development, construction, and launch cost of the {\it Mars Observer\/} spacecraft\cr $1.1\times 10^{9}$ & 1994 USA dollars & Worldwide Visa and MasterCard fraud in 1993\cr $1.5\times 10^{9}$ & 1994 USA dollars & Planned total cost of the AXAF X-ray mission\cr $1.6\times 10^{9}$ & 1994 USA dollars & Estimated cost of the CERN Large Hadron Collider\cr $1.7\times 10^{9}$ & 1994 USA dollars & Barclays 1994 half-year profits\cr $1.8\times 10^{9}$ & 1994 USA dollars & Amount of food stamp fraud in the USA in 1993\cr $3.5\times 10^{9}$ & 1994 USA dollars & Planned total cost of the {\it Cassini\/} spacecraft\cr $3.8\times 10^{9}$ & 1994 USA dollars & Microsoft revenue in 1993\cr $1\times 10^{10}$ & 1994 USA dollars & Rough monetary losses associated with BCCI\cr $1.3\times 10^{10}$ & 1994 USA dollars & Lockheed revenue in 1993\cr $1.4\times 10^{10}$ & 1994 USA dollars & NASA planned 1995 budget\cr $1.5\times 10^{10}$ & 1994 USA dollars & Rough United Nations yearly budget\cr $2.8\times 10^{10}$ & 1994 USA dollars & Planned cost for the space station\cr $4.4\times 10^{10}$ & 1994 USA dollars & Total cost of the first 20 B-2 Stealth bombers\cr $5\times 10^{10}$ & 1994 USA dollars & Clinton administration 1995 loan guarantee to Mexico\cr $1\times 10^{11}$ & 1994 USA dollars & Rough annual gap between USA IRS estimates of federal taxes due and tax revenues\cr & & actually collected\cr $2.6\times 10^{11}$ & 1994 USA dollars & United States 1994 military spending\cr $2.6\times 10^{11}$ & 1994 USA dollars & United States 1994 predicted defecit\cr $8\times 10^{11}$ & 1994 USA dollars & United States 1994 entitlement spending (e.g. social security, medicare, medicaid,\cr & & food stamps, unemployment compensation, farm aid, federal pensions)\cr $1\times 10^{12}$ & 1994 USA dollars & Rough total United States health care spending in 1994\cr $1.3\times 10^{12}$ & 1994 USA dollars & United States 1994 tax receipts\cr $1.5\times 10^{12}$ & 1994 USA dollars & United States 1994 federal government spending\cr $3.5\times 10^{12}$ & 1994 USA dollars & United States antipoverty spending since 1965\cr $4.4\times 10^{12}$ & 1994 USA dollars & United States 1994 national debt\cr $6.4\times 10^{12}$ & 1994 USA dollars & United States 1994 gross domestic product\cr $1.4\times 10^{13}$ & 1994 USA dollars & United States 1994 unfunded liabilities for social security, medicare, federal\cr & & civil-service retirement and military retirement\cr $3.1\times 10^{14}$ & 1994 USA dollars & World 1994 GDP\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $0.004 $ & & Black velvet optical light albedo\cr $0.012 $ & & Black cloth optical light albedo\cr $0.04 $ & & Halley's comet optical light albedo\cr $0.068 $ & & Moon optical light albedo\cr $0.14 $ & & Mars optical light albedo\cr $0.40 $ & & Earth optical light albedo\cr $0.80 $ & & White paper optical light albedo\cr $0.85 $ & & Venus optical light albedo\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $1\times 10^{-10}$ & pc$^{-3}$ & Space density of X-ray binaries in the Milky Way\cr $5\times 10^{-7}$ & pc$^{-3}$ & Space density of pulsars in the solar neighborhood\cr $3\times 10^{-6}$ & pc$^{-3}$ & Space density of cataclysmic variables in the solar neighborhood\cr $0.1$ & pc$^{-3}$ & Space density of main sequence stars in the solar neighborhood\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $1\times 10^{-9}$ & Mpc$^{-3}$ & Ultraluminous IRAS galaxies\cr $1\times 10^{-9}$ & Mpc$^{-3}$ & Quasars\cr $1\times 10^{-7}$ & Mpc$^{-3}$ & QSOs\cr $1\times 10^{-7}$ & Mpc$^{-3}$ & FR II radio galaxies (edge-brightened)\cr $5\times 10^{-6}$ & Mpc$^{-3}$ & FR I radio galaxies (not edge-brightened)\cr $1\times 10^{-4}$ & Mpc$^{-3}$ & Seyfert galaxies\cr $0.1$ & Mpc$^{-3}$ & Field galaxies\cr $0.6$ & Mpc$^{-3}$ & Group galaxies\cr } \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $-26.8$ & & V apparent magnitude of the Sun\cr $-12.5$ & & V apparent magnitude of the full Moon\cr $-4.4$ & & V apparent magnitude of Venus at its brightest\cr $-1.5$ & & V apparent magnitude of Sirius\cr $0.1$ & & V apparent magnitude of the LMC\cr $0.5$ & & V apparent magnitude of Betelgeuse\cr $3.4$ & & V apparent magnitude of M31\cr $6.5$ & & V apparent magnitude of naked eye limit at a dark site\cr $9$ & & V apparent magnitude of 50-mm binocular limit\cr $10.5$ & & V apparent magnitude of the $z=0.00363$ Seyfert 2 NGC 1068\cr $11.6$ & & V apparent magnitude of the $z=0.00170$ H II region galaxy NGC 5408\cr $12.8$ & & V apparent magnitude of the $z=0.158$ quasar 3C273\cr $13.6$ & & V apparent magnitude of the $z=0.0167$ Seyfert 1 NGC 7469\cr $14.5$ & & V apparent magnitude of 12-in telescope visual limit\cr $15.3$ & & V apparent magnitude of the $z=0.239$ quasar PG 0953+414 (ApJ 435, L12)\cr $19.55$ & & V apparent magnitude of the $z=3.67$ quasar DHM $0054-284$ \cr $23.5$ & & V apparent magnitude of 200-in telescope photographic limit\cr $25.5$ & & V apparent magnitude of a typical Cepheid in M100 (ApJ 435, L33)\cr $29.5$ & & V apparent magnitude limit of an 18-hour exposure with HST\cr } % Some of the values in the above table are taken from Sky and Telescope; Jan 1996; page 44. \vskip 0.1 in \halign{\hbox{#}&\quad\hbox{#}&\quad\hbox{#}\cr % $-27.5$ & & $M_{\rm V}$ of the $z=0.158$ quasar 3C273\cr $-24.1$ & & $M_{\rm V}$ of the $z=0.239$ quasar PG 0953+414 (ApJ 435, L12)\cr $-21.1$ & & $M_{\rm V}$ of M31\cr $-21.0$ & & $M_{\rm V}$ of a typical Seyfert host galaxy\cr $-19.5$ & & $M_{\rm V}$ limit on the host galaxy of the $z=0.239$ quasar PG 0953+414 (ApJ 435, L12)\cr $-18.5$ & & $M_{\rm V}$ of the LMC\cr $-6.0$ & & $M_{\rm V}$ of Betelgeuse \cr $4.4$ & & $M_{\rm V}$ of the most luminous star in Alpha Centauri\cr $4.79$ & & $M_{\rm V}$ of the Sun\cr } \vskip 0.1 in \item {\bf Note: } I assume an inflationary $(\Omega_0=1.0)$ dust-filled Friedmann-Robertson-Walker universe with $H_0=50$ km s$^{-1}$ Mpc$^{-1} = 1.62\times 10^{-18}$ s$^{-1}$ for all calculations. Space densities are given for ``here and now.'' \end