The Physics of the Universe - Difficult Topics Made Understandable


Introduction
 
Main Topics
 
Important Dates and Discoveries
 
Important Scientists
 
Cosmological Theories Through History
 
The Universe By Numbers
 
Glossary of Terms
 
A Few Random Facts
 
Sources

 
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lukem@lukemastin.com
 
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Luke Mastin
 

The Universe By Numbers

Exponential or Scientific Notation:
It is easier to write very large numbers such as 100,000,000 as 108 (1 followed by 8 0s).
Similarly very small numbers are written using negative exponents, e.g. 0.0000001 is 10-7 (the 1 is seven places to the right of the decimal point).
Bear in mind though that 109 is ten times the size of 108, and 1018 is ten billion times larger.
Some of the numbers, both small and large, that are bandied around in modern physics are very difficult to grasp. Below is a table listing - from the infinitesimally small to the incomprehensibly large - some of the numbers which are relevant to the subject matter.

Obviously, the units used affects these numbers (e.g. metres, kilometres, miles, light years, etc), but I have tried to use consistent metric units throughout: metres for distance, seconds for time, metres/second for speed, degrees Kelvin for temperature, kilograms for mass, kilograms/metre3 for density, Joules for energy, Coulombs for electrical charge, kilopascals for pressure.

The Scale of the Universe:
Cary Huang has created an excellent interactive graphical representation of the scale of the universe, from strings to the edge of the observable universe. Click to open.
The different types of measurements are also colour-coded for convenience:
Colour-coding of The Universe By Numbers

0.00000000000000000000000000000000000000000
00054
5.4 10-44
Planck Time (in seconds), the shortest meaningful interval of time, and the earliest time the known universe can be measured from.
0.000000000000000000000000000000000001616
1.616 10-35
Planck Length (in metres), the size of a hypothetical string. Lengths smaller than this are considered not make any physical sense in our current understanding of physics.
0.000000000000000000000000000000911
9.11 10-31
Approximate mass (in kilograms) of a stationary electron.
0.000000000000000000000000001
1 10-27
Approximate density (in kg/metre3) of the universe as a whole.
0.000000000000000000000000001673
1.673 10-27
Approximate mass (in kilograms) of a proton.
0.000000000000000000000000001675
1.675 10-27
Approximate mass (in kilograms) of a neutron.
0.000000000000000000000000005
5 10-27
Estimated critical density (in kg/metre3) of the universe, to allow a steady state between expansion and contraction (about 5 10-30 g/cm3).
0.00000000000000000000002
2 10-23
Effective radius (in metres) of a neutrino particle.
0.0000000000000000001602
1.602 10-19
Elementary charge (in Coulombs), i.e. the negative charge of a single electron, or the positive charge of a single proton.
0.00000000000000000052
5.2 10-19
Approximate energy (in Joules) of photons in visible light.
0.000000000000000001
1 10-18
Upper limit (in metres) on the size of the quark particles that make up protons and neutrons.
0.000000000000000001
1 10-18
Smallest object observable and measurable by current science.
0.00000000000000001
1 10-17
Approximate density (in kg/metre3) of the best vacuum achievable in a laboratory.
0.000000000000002818
2.818 10-15
Effective radius (in metres) of an electron according to classical theory.
0.00000000000001
1 10-14
Range (in metres) of the weak nuclear force within the nucleus.
0.00000000000008187
8.187 10-14
Rest mass-energy (in Joules) of an electron.
0.000000000001
1 10-12
Approximate mass (in kilograms) of the average human cell.
0.000000000005
5 10-12
Longest wavelength (in metres) of gamma rays.
0.000000000025
2.5 10-11
Radius (in metres) of a hydrogen atom.
0.0000000005972
5.972 10-10
Rest mass-energy (in Joules) of an alpha particle.
0.0000004
4 10-7
Approximate wavelength (in metres) of violet light, the shortest in the visible spectrum.
0.0000007
7 10-7
Approximate wavelength (in metres) of red light, the long in the visible spectrum.
0.74
7.4 10-1
Proportion of all matter in the universe composed of hydrogen.
0
0 100
Temperature (in Kelvin) of absolute zero, the lowest possible temperature (equivalent to -273.15 Celsius).
1.48
1.48 100
Density (in kg/metre3) of Earths atmosphere at sea level.
2.725
2.725 100
Temperature (in Kelvin) of cosmic microwave background radiation.
3.14
3.14 100
Pi, the ratio of a circle's circumference to its diameter (more accurately 3.14159265358979323846...)
9.8
9.8 100
Strength of the gravitational field (in metres/second/second) at the Earth's surface.
92
9.2 101
Number of naturally occurring elements.
100
1 102
Wavelength (in metres) of the lowest shortwave radio frequency.
101
1.01 102
Standard atmospheric pressure (in kilopascals) for Earth at sea level.
331
3.31 102
Speed (in metres/second) of sound in air at sea level and 0C.
464
4.64 102
Speed (in metres/second) of the Earth's rotation at the equator.
1,000
1 103
Density (in kg/metre3) of liquid water at 4C.
1,366
1.366 103
Total solar radiation (in Joules) received from the Sun by one square metre of the Earth's surface per second.
5,780
5.78 103
Temperature (in Kelvin) of the surface of the Sun.
29,800
2.98 104
Speed (in metres/second) of the Earth in orbit around the Sun.
145,000
1.45 105
Ratio of the size of an atom of hydrogen to its nucleus (the ration of other more complex atoms is less).
150,000
1.5 105
Density (in kg/metre3) of the core of the Sun.
200,000
2 105
Speed (in metres/second) of the Solar System in orbit around the Milky Way galaxy.
552,000
5.52 105
Speed of the Milky Way galaxy, relative to the cosmic microwave background radiation.
3,474,000
3.474 106
Diameter (in metres) of the Moon.
12,756,000
1.2756 107
Equatorial diameter (in metres) of the Earth.
15,600,000
1.56 107
Temperature (in Kelvin) at the core of the Sun.
384,000,000
3.84 108
Orbital distance (in metres) of the Moon from the Earth.
299,792,458
2.998 108
Speed (in metres/second) of light (or any electromagnetic radiation) in a vacuum.
1,000,000,000
1 109
Approximate density (in kg/metre3) of white dwarf, or dead, stars.
1,390,000,000
1.39 109
Diameter (in metres) of the Sun (1.39 million kilometres).
10,000,000,000
1 1010
Temperature (in Kelvin) in a supernova explosion.
80,000,000,000
8 1010
Rough estimate of the number of stars in the Milky Way galaxy (estimates vary up to 4 1011).
150,000,000,000
1.5 1011
Mean distance (in metres) between the Earth and the Sun (150 million kilometres, or 1 Astronomical Unit).
380,000,000,000
3.8 1011
Pressure (in kilopascals) inside the core of the Earth.
900,000,000,000
9 1011
Estimated optical diameter (in metres) of Betelgeuse, a red supergiant star.
3,000,000,000,000
3 1012
Estimated optical diameter (in metres) of VY Canis Majoris, a red hypergiant and the largest known star (about 2,000 times the size of our Sun).
10,000,000,000,000
1 1013
Approximate diameter (in metres) of the Solar System (10 billion kilometres).
20,000,000,000,000
2 1013
Approximate density (in kg/metre3) of the universe at the electroweak epoch, about 1012 seconds after the Big Bang.
90,000,000,000,000
9 1013
Theoretical total mass-energy (in Joules) of one gram of matter.
100,000,000,000,000
1 1014
Estimated number of cells in the human body (9 out of every 10 being bacteria cells).
9,460,000,000,000,000
9.46 1015
Distance (in metres) travelled by light in one year (1 light year or 9.46 trillion kilometres).
25,000,000,000,000,000
2.5 1016
Pressure (in kilopascals) inside the core of the Sun.
40,000,000,000,000,000
4 1016
Distance (in metres) to Proxima Centauri, the nearest star after the Sun (about 4.23 light years).
141,000,000,000,000,000
1.41 1017
Half-life (in seconds) of uranium (4.468 billion years).
200,000,000,000,000,000
2 1017
Density (in kg/metre3) of atomic nuclei and neutron stars.
432,000,000,000,000,000
4.32 1017
Estimated age (in seconds) of the universe, assuming 13.7 billion years since the Big Bang.
1,000,000,000,000,000,000,000
1 1021
Approximate diameter (in metres) of galactic disk of Milky Way galaxy (100,000 light years).
70,000,000,000,000,000,000,000
7 1022
Rough estimate of the number of stars in the observable universe (estimates vary from 1022 to 1024).
22,300,000,000,000,000,000,000
2.23 1022
Distance (in metres) to the Andromeda Galaxy, the nearest galaxy to our own (2.36 million light years).
2,000,000,000,000,000,000,000,000
2 1024
Diameter (in metres) of the Virgo Supercluster, the cluster of galaxies which includes out own Local Group of galaxies (about 200 million light years).
6,000,000,000,000,000,000,000,000
6 1024
Mass (in kilograms) of the Earth.
386,000,000,000,000,000,000,000,000
3.86 1026
Total energy output (in Joules) of the Sun each second.
920,000,000,000,000,000,000,000,000
9.2 1026
Approximate diameter (in metres) of the visible universe (92 billion light years).
1,000,000,000,000,000,000,000,000,000
1 1027
Temperature (in Kelvin) of the universe 10-35 seconds after the Big Bang, at the start of the inflationary epoch.
2,000,000,000,000,000,000,000,000,000,000
2 1030
Mass (in kilograms) of the Sun (1 solar mass).
40,000,000,000,000,000,000,000,000,000,000
4 1031
Mass (in kilograms) of Betelgeuse, a red supergiant star (about 20 solar masses).
141,700,000,000,000,000,000,000,000,000,000
1.417 1032
Planck Temperature, the temperature (in Kelvin) of the universe at 1 Planck Time after the Big Bang.
10,000,000,000,000,000,000,000,000,000,000,000,
000,000
1 1040
Approximate ratio of the strength of the electromagentic to the gravitational force between sub-atomic particles.
36,000,000,000,000,000,000,000,000,000,000,000,
000,000
3.6 1040
Mass (in kilograms) of OJ287, the largest measured supermassive black hole.
687,000,000,000,000,000,000,000,000,000,000,000,
000,000
6.87 1041
Gravitational binding energy (in Joules) of the Sun.
120,000,000,000,000,000,000,000,000,000,000,000,
000,000,000
1.2 1044
Estimated energy (in Joules) released in a supernova explosion.
30,000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000
3 1052
Estimated mass (in kilograms) of the observable universe.
4,000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000,
000
4 1069
Estimated total mass-energy (in Joules) of the observable universe.
100,000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000,000,
000,000,000
1 1080
Estimate the total number of fundamental particles in the observable universe (other estimates go up to 1085).
5,100,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000
5.1 1096
Planck density, the density (in kg/metre3) of the universe at one unit of Planck time after the Big Bang.
 
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Introduction | Main Topics | Important Dates and Discoveries | Important Scientists | Cosmological Theories | The Universe By Numbers | Glossary of Terms | A Few Random Facts | Sources
 
© 2009 Luke Mastin