Category Archives: Physics

How to Weigh a Supermassive Black Hole?

An artist's impression of a black hole.Black Holes

Black holes are known to exist at the centres of most galaxies, including our own Milky Way.  The masses of those black holes are correlated to many of the properties of their host galaxies, which strongly suggests that galaxies and black holes evolve together.  Measuring their masses Continue reading How to Weigh a Supermassive Black Hole?

Fallen from Outer Space…

A photograph of Daredevil Felix Baumgartner, as he boldly prepares to jump off his high altitude capsule for the ultimate record-breaking space dive on 14th October 2012.

Record-Breaking Space Dive

14th October 2012.  During his ultimate high-altitude parachute jump, Felix Baumgartner spends approximately 4 minutes and 22 seconds in freefall, at the maximum speed of 1,342 kilometres per hour.  Continue reading Fallen from Outer Space…

Let There Be Light…

A photograph showing the sun reflecting over the waters at Loch Kathrine through a curtain of trees. Low sun. Image: NaturPhilosophieFiat Lux…

Light.  Most of us take it for granted during the day.  And at night, we have learned to domesticate it.  Light, the natural agent that stimulates our sense of sight and makes things around us visible.  Continue reading Let There Be Light…

Constant Matters

Pi_NumberPhysical Constants (SI Units)

Avogadro Constant N_{A} = 6.022 \times 10^{23} mol^{-1}

Bohr Radius a_0 = 5.29 \times 10^{-11} m

Boltzmann Constant k = 1.381 \times 10^{-23} JK^{-1}

Charge on an Electron e = - 1.602 \times 10^{-19} C

Gravitational Constant G = 6.673 \times 10^{-11} Nm^{2} kg^{-2}

Magnitude of Acceleration due to Gravity g = 9.81 m s^{-2}

Permeability of Free Space \mu_{0} = 4 \pi \times 10^{-7} T m A^{-1}

Permittivity of Free Space \epsilon_{0} = 8.854 \times 10^{-12} C^{2} N^{-1} m^{-2}

Speed of Light in a vacuum c = 2.998 \times 10^{8} m s^{-1}