Primeval (or Primordial) Soup:
The theory of the origin of life on Earth first put forward by Alexander Oparin, whereby a “soup” of organic molecules could be created in a “reducing” oxygen-less atmosphere through the action of sunlight, creating the necessary building blocks for the evolution of life.
Principle of Equivalence:
The idea that no experiment can distinguish the acceleration due to gravity from the inertial acceleration due to a change of velocity (or acceleration).
Principle of Relativity:
The idea, first expressed by Galileo Galilei in 1632 and also known as the principle of invariance, that the fundamental laws of physics are the same in all inertial frames and that, purely by observing the outcome of mechanical experiments, one cannot distinguish a state of rest from a state of constant velocity. Thus, all uniform motion is relative, and there is no absolute and well-defined state of rest.
Probability Wave (or Wave Function):
A description of the probability that a particle in a particular state will be measured to have a given position and momentum. Thus, a particle (an electron, photon or any other kind of particle), when not being measured or located, takes the form of a field or wave of probable locations, some being more probable or likely than others.
Prokaryotes and Eukaryotes:
Prokaryotes are primitive organisms that lack a cell nucleus or any other membrane-bound organelles. Most prokaryotes are single-celled (although some have multicellular stages in their life-cycles), and they are divided into two main domains, bacteria and archaea.
Eukaryotes, on the other hand, are organisms whose cells contain a nucleus and are organized into complex structures enclosed within membranes. Most living organisms (including all animals, plants, fungi and protists) are eukaryotes.
Proton:
One of the two main building blocks (along with the neutron) of the nucleus at the centre of an atom. Protons carry a positiveelectrical charge, equal and opposite to that of electrons, and are made up of two “up” quarks and one “down” quark. The number of protons in an atom’s nucleus determines its atomic number and thus which chemical element it represents.
Pulsar:
A highly-magnetized rapidly-rotating neutron star that sweeps regular pulses of intense electromagnetic radiation (radio waves) around space like a lighthouse. The intervals between pulses are very regular, ranging from 1.4 milliseconds to 8.5 seconds depending on the rotation period of the star. A pulsar generally has a mass similar to our own Sun, but a diameter of only around 10 kilometres.
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