X2 consists of small notes on facts, culture, and history of physics in Persian.

Using, printing, and publishing these texts for non-commercial purposes is free, provided they are not altered in any sense (including text, style, and orthography). For any other use, author's permission is needed.

X2 (2024)                                        back to mamwad
X2-181 (2024/07/04) pdf The gravitational radiation III

X2-180 (2024/05/04) pdf The gravitational radiation II

X2-179 (2024/04/01) pdf The biggest of artificial molecules

X2-178 (2024/02/22) pdf We, and the increase of the carbon dioxide in the atmosphere

X2-177 (2024/01/24) pdf Is water blue?

X2 (2023)                                        back to mamwad
X2-176 (2023/11/24) pdf Why is Hydrogen-3 unstable?

X2-175 (2023/10/21) pdf The smallest and the biggest of atoms

X2-174 (2023/08/04) pdf The biggest star

X2-173 (2023/07/13) pdf Earth's global temperature

X2-172 (2023/05/17) pdf Energy consumption: human and the hummingbird

X2-171 (2023/04/23) pdf The battery's energy density

X2-170 (2023/02/23) pdf The blackest thing

X2-169 (2023/01/27) pdf Water in the atmosphere and the surface of the earth

X2 (2022)                                        back to mamwad
X2-168 (2022/11/27) pdf Sound speed in neutron stars

X2-167 (2022/10/21) pdf Bond energy

X2-166 (2022/08/25) pdf Collision with the earth, and the global warming

X2-165 (2022/07/23) pdf Air speed, water speed

X2-164 (2022/05/25) pdf Penetration of the sunlight in the sea water

X2-163 (2022/04/21) pdf Earth's albedo, and the global warming

X2-162 (2022/02/21) pdf Jupiter too is very big

X2-161 (2022/01/20) pdf The sun is very big

X2 (2021)                                        back to mamwad
X2-160 (2021/11/26) pdf Critical water

X2-159 (2021/10/22) pdf The ratio of the volume of a ball to the volume of a cube

X2-158 (2021/08/27) pdf The sun's hydrogen

X2-157 (2021/07/22) pdf The huge intermolecular force

X2-156 (2021/05/29) pdf Temperature change in water and soil

X2-155 (2021/04/25) pdf The densities of the gases

X2-154 (2021/02/26) pdf If the sun was a white dwarf II

X2-153 (2021/01/26) pdf If the sun was a white dwarf I

X2 (2020)                                        back to mamwad
X2-152 (2020/11/25) pdf Expansion of the water as a result of cooling near the freezing point

X2-151 (2020/10/29) pdf Improving the estimation of the cosmological constant with a suitable mass?

X2-150 (2020/08/28) pdf Time in cosmic travels

X2-149 (2020/07/29) pdf Tiny friction coefficient

X2-148 (2020/05/30) pdf The energy that the earth receives from the sun, as a function of position and time

X2-147 (2020/04/25) pdf The densities of the liquids

X2-146 (2020/02/24) pdf The solar energy and absorbing carbon from the atmosphere

X2-145 (2020/01/29) pdf The speed of the displacement of the surface of the earth

X2 (2019)                                        back to mamwad
X2-144 (2019/11/26) pdf Glaciers and the compression of their beds

X2-143 (2019/10/29) pdf Precipitation

X2-142 (2019/08/27) pdf The radii of neutral hydrogen-like particles

X2-141 (2019/07/29) pdf Sunlight and its composition

X2-140 (2019/05/26) pdf Light intensity in the environment

X2-139 (2019/04/19) pdf The magnetic field of current-carrying wires

X2-138 (2019/02/27) pdf The electric discharge in the atmosphere, and the magnetic field due to it

X2-137 (2019/01/26) pdf Metals in the Solar System

X2 (2018)                                        back to mamwad
X2-135 (2018/11/28) pdf Solar sail

X2-135 (2018/10/26) pdf Human, and the energy balance of the earth

X2-134 (2018/08/29) pdf Time in space travels

X2-133 (2018/07/26) pdf Fuel consumption of a plane

X2-132 (2018/05/31) pdf Carbon on the earth

X2-131 (2018/04/27) pdf Water vapor in the atmosphere

X2-130 (2018/02/28) pdf Fall in honey

X2-129 (2018/01/28) pdf The field strength which polarizes the vacuum

X2 (2017)                                        back to mamwad
X2-128 (2017/11/29) pdf The quantum and thermal line-widths

X2-127 (2017/10/29) pdf The effect of temperature and pressure in the ocean on the density of water

X2-126 (2017/08/24) pdf If the Milky Way had a quasar

X2-125 (2017/07/28) pdf Eternal sunset

X2-124 (2017/05/29) pdf The age of the universe, and the catastrophe of 
                        the estimation of the cosmological constant

X2-123 (2017/04/17) pdf The power and the life time of a white dwarf

X2-122 (2017/02/27) pdf Wheat as food

X2-121 (2017/01/28) pdf Pluto's surface temperature

X2 (2016)                                        back to mamwad
X2-120 (2016/11/30) pdf If the arctic ice melts

X2-119 (2016/10/31) pdf If the moon becomes attached to the earth, what would be the length of the day?

X2-118 (2016/08/27) pdf How much air is needed to survive?

X2-117 (2016/07/29) pdf Cooling, using evaporation

X2-116 (2016/05/30) pdf The compact object in the center of the Milky Way

X2-115 (2016/04/29) pdf The speed of water waves

X2-114 (2016/02/28) pdf The gravitational potential energy of a mountain

X2-113 (2016/01/29) pdf Archimedes and moving the earth

X2 (2015)                                        back to mamwad
X2-112 (2015/11/30) pdf Energetic cosmic particles

X2-111 (2015/10/30) pdf Quantum mechanics and Iran, III: relativistic quantum mechanics

X2-110 (2015/08/29) pdf Internal heating of planets

X2-109 (2015/07/30) pdf The habitable zone, and the evolution of the sun

X2-108 (2015/05/29) pdf Remaining young in the gravitational field

X2-107 (2015/04/30) pdf The impulse, force, and pressure due to the rain

X2-106 (2015/02/24) pdf The water in the clouds

X2-105 (2015/01/26) pdf The minimum of the melting temperature of ice

X2 (2014)                                        back to mamwad
X2-104 (2014/11/28) pdf Revolution of the sun around the galactic center

X2-103 (2014/10/30) pdf Melting of ice, and convection

X2-102 (2014/08/25) pdf Freezing water, and cracking vessel

X2-101 (2014/07/26) pdf Perspiration

X2-100 (2014/05/30) pdf Buoyancy of the human body

X2-099 (2014/04/26) pdf The density of the rocky planets

X2-098 (2014/02/22) pdf Reducing the time needed to cook an egg

X2-097 (2014/01/31) pdf Evaporating water, raising water

X2 (2013)                                        back to mamwad
X2-096 (2013/11/29) pdf Change of the carbon dioxide ratio in the atomsphere

X2-095 (2013/10/30) pdf Which is hotter, boiling water or water vapor?

X2-094 (2013/08/31) pdf Constant angular velocity in Keplerian orbits

X2-093 (2013/07/30) pdf Quantum mechanics and Iran, II: modern quantum mechanics

X2-092 (2013/05/30) pdf The intensity and the effective intensity of the sunlight

X2-091 (2013/04/29) pdf The volume difference of liquid and gas, and the latent heat of vaporization

X2-090 (2013/02/28) pdf The laser reflected from the lunar surface

X2-089 (2013/01/30) pdf Time needed to cook an ostrich egg

X2 (2012)                                        back to mamwad
X2-088 (2012/11/29) pdf Planck mass

X2-087 (2012/10/30) pdf The boling point of the mixture of two immiscible fluids

X2-086 (2012/08/31) pdf Apparent diameters of heavenly bodies

X2-085 (2012/07/31) pdf The electric charge does not depend on the velocity

X2-084 (2012/05/30) pdf The uncertainty, and an old model of the nucleus

X2-083 (2012/04/27) pdf Ultrasonic humidifiers

X2-082 (2012/02/29) pdf A supernova as luminous as the full moon

X2-081 (2012/01/28) pdf Cooling of the earth, and age of the earth

X2 (2011)                                        back to mamwad
X2-080 (2011/11/30) pdf Thin tubes and fluid current

X2-079 (2011/10/30) pdf Multipole radiation and the life of excited electron states

X2-078 (2011/08/10) pdf Escaping the increasing power of the sun

X2-077 (2011/07/29) pdf The focal length of thin lenses

X2-076 (2011/05/30) pdf Scattering of the sunlight in the earth's atmosphere

X2-075 (2011/04/30) pdf The angle of the rainbow

X2-074 (2011/02/25) pdf Threshold of vision

X2-073 (2011/01/27) pdf The smooth surface of a neutron star

X2 (2010)                                        back to mamwad
X2-072 (2010/11/26) pdf Magnetar

X2-071 (2010/10/30) pdf Motion with a fixed speed, in a fixed direction relative to the north

X2-070 (2010/08/28) pdf The collision which created the moon

X2-069 (2010/07/28) pdf The magnetic force felt by nonmagnetic materials

X2-068 (2010/05/28) pdf The fastest and slowest living creatures

X2-067 (2010/04/30) pdf Quantum mechanics and Iran, I: old quantum mechanics

X2-066 (2010/02/27) pdf Turning off LEDs to save electricity?

X2-065 (2010/01/29) pdf Melting temperature versus pressure

X2 (2009)                                        back to mamwad
X2-064 (2009/11/28) pdf Rotation of stars

X2-063 (2009/10/29) pdf The speed of propagation of the electric field, and the speed of charges

X2-062 (2009/08/27) pdf Maximum of the speed in running

X2-061 (2009/07/30) pdf Sharpness of phase transition

X2-060 (2009/05/30) pdf Escaping the gravitational field

X2-059 (2009/04/24) pdf Relativity and Iran

X2-058 (2009/02/27) pdf Energy released in an earthquake

X2-057 (2009/01/22) pdf Tunneling probability for electron and proton

X2 (2008)                                        back to mamwad
X2-056 (2008/11/30) pdf Adiabatic, isothermal, and evanescent sound

X2-055 (2008/10/31) pdf Surface tension in the nucleus

X2-054 (2008/08/29) pdf Thermodynamics and Iran, III: 
                        Statistical mechanics

X2-053 (2008/07/28) pdf Moon's halo, and water droplets

X2-052 (2008/05/31) pdf The electric field of the earth

X2-051 (2008/04/29) pdf The energy of rain

X2-050 (2008/02/29) pdf Are green leaves optimum for photosynthesis?

X2-049 (2008/01/31) pdf Density of elements

X2 (2007)                                        back to mamwad
X2-048 (2007/11/09) pdf Energy saving: turning off a lamp, 
                        or changing it

X2-047 (2007/10/13) pdf Energy released in the collision of 
                        a heavenly body with the earth

X2-046 (2007/08/10) pdf Thermodynamics and Iran, II: 
                        Clausius and Kelvin

X2-045 (2007/07/11) pdf Development and the price of goods

X2-044 (2007/05/31) pdf Multi-question quiz

X2-043 (2007/04/29) pdf Changing scales versus time

X2-042 (2007/02/28) pdf Sound and the amplitude of the 
                        displacement of the air molecules

X2-041 (2007/01/19) pdf Are all chemical reactions incomplete?

X2 (2006)                                        back to mamwad
X2-040 (2006/11/24) pdf Desalination of water: 
                        reverse osmosis versus distillation

X2-039 (2006/10/12) pdf Power consumption in the world, 
                        and the water of the oceans

X2-038 (2006/08/04) pdf Thermodynamics and Iran, I: 
                        Rumford, Carnot, and Joule

X2-037 (2006/07/06) pdf Old cars and fuel consumption

X2-036 (2006/05/19) pdf The magnetic fields of planets and stars

X2-035 (2006/04/02) pdf Windows and energy consumption

X2-034 (2006/02/24) pdf Elecetromagnetics and Iran, III: 

X2-033 (2006/01/06) pdf Why there are no very-large animals
                        on the earth?

X2 (2005)                                        back to mamwad
X2-032 (2005/11/25) pdf The nucleons and the photons of the universe

X2-031 (2005/10/07) pdf The eye, the photographic film, 
                        and the digital camera

X2-030 (2005/08/31) pdf Swimming in heavy water

X2-029 (2005/07/27) pdf The power of the stars

X2-028 (2005/05/27) pdf Chemical energy, nuclear energy

X2-027 (2005/04/26) pdf The power a human needs to survive

X2-026 (2005/02/28) pdf Molecular distances and energies, 
                        and the bulk modulus

X2-025 (2005/01/15) pdf Elecetromagnetics and Iran, II: 

X2 (2004)                                        back to mamwad
X2-024 (2004/11/12) pdf The tidal effect of the Moon on the Earth, 
                        and the change of the sidereal day

X2-023 (2004/10/15) pdf Water wasted due to faulty faucets in Tehran

X2-022 (2004/08/25) pdf Complexity of the living organisms and galaxies

X2-021 (2004/07/31) pdf Solar energy, and the world's energy consumption

X2-020 (2004/05/08) pdf Elecetromagnetics and Iran, I: 
                        the electrostatics of Coulomb and Poisson

X2-019 (2004/04/10) pdf Density of the universe at different scales

X2-018 (2004/02/14) pdf The carbon dioxide emmited by human into the atmosphere

X2-017 (2004/01/12) pdf Global warming, and the rise of ocean levels

X2 (2003)                                        back to mamwad
X2-016 (2003/12/13) pdf Galileo and the Leaning Tower of Pisa

X2-015 (2003/10/31) pdf The number of the nucleons of the observable universe

X2-014 (2003/09/24) pdf The gravitational radiation

X2-013 (2003/07/28) pdf The surface tension, and the latent heat of evaporation

X2-012 (2003/06/20) pdf The resolving power of the eye, and the heavenly bodies

X2-011 (2003/04/29) pdf Birth of the new science and Iran, III: 
                        from Lagrange to Hamilton

X2-010 (2003/03/21) pdf Cloud, rain, hailstone

X2-009 (2003/01/31) pdf The nearest neighbor of the Earth (after the Moon)

X2 (2002)                                        back to mamwad
X2-008 (2002/12/25) pdf Birth of the new science and Iran, II: 

X2-007 (2002/10/22) pdf Birth of the new science and Iran, I: 
                        from Kopernik to Galileo

X2-006 (2002/08/06) pdf The history of the oblateness of the earth

X2-005 (2002/07/14) pdf The lightning

X2-004 (2002/05/20) pdf Birth of the matrix mechanics in the second half of 1925

X2-003 (2002/04/09) pdf Heisenberg, Born, and Pauli

X2-002 (2002/02/22) pdf Power consumption per capita, and production per capita

X2-001 (2002/01/06) pdf The industrial revolution in terms of the spinning machine