mass defect
Whenever two or more objects are bound together by strong forces, there is a binding energy - the energy needed to be able to get these objects apart. Since Einstein, we know that energy and mass are equivalent. To this binding energy there corresponds a ...
magnetic field
The magnetic force is a force by which electric currents (i.e. moving electric charges) act on each other; the magnetic field is the associated field. All phenomena related to the magnetic force or magnetic field are subsumed under the heading of magnetism. ...
Lorentz transformation
Central set of formulae of special relativity: Formulae that define how to go back and forth between two inertial reference frames that are in relative motion; more precisely: if an event is defined in terms of the space- and time coordinates of one of the ...
loop quantum gravity
Candidate for a theory of quantum gravity. Loop quantum gravity is an attempt to apply the concepts and laws of quantum theory directly to the geometry that is at the heart of general relativity. A brief description can be found on the page Loop quantum ...
lookback time
The time that light from a distance body needs to reach us here on earth. Lookback time, defined using the cosmic time coordinate, is one way of defining distances in an expanding ...
logarithmic
In graphic representations of physical data, a way of plotting values according to their common logarithm. In mathematics, the logarithm is the inverse function to exponentiation. That means the logarithm of a given number x is the exponent to which another ...
Lockman hole
A region in the sky, located in the constellation Ursa Major (better known as the Big Dipper), and covering an area about 75 times that of the full moon. Pointing their telescopes at this region, astronomers will encounter only negligible ...
local group
The galaxy cluster of which our very own galaxy, the Milky Way, is a member. Cosmically speaking, the local group is rather puny - its only members apart from the Milky Way are the Andromeda galaxy, the galaxy M33 and a number of dwarf galaxies (such as the ...
