Search results
Results from the WOW.Com Content Network
The physical universe is defined as all of space and time [a] (collectively referred to as spacetime) and their contents. [10] Such contents comprise all of energy in its various forms, including electromagnetic radiation and matter, and therefore planets, moons, stars, galaxies, and the contents of intergalactic space.
The ancient Greek concept of four basic elements, these being earth (γῆ gê), water (ὕδωρ hýdōr), air (ἀήρ aḗr), and fire (πῦρ pŷr), dates from pre-Socratic times and persisted throughout the Middle Ages and into the Early modern period, deeply influencing European thought and culture.
The basic definition of Cosmology is the science of the origin and development of the universe. In modern astronomy, the Big Bang theory is the dominant postulation. Philosophy of cosmology is an expanding discipline, directed to the conceptual foundations of cosmology and the philosophical contemplation of the universe as a totality.
The Universe is a system made up of heaven and Earth and the elements which are contained in them. There are "five elements, situated in spheres in five regions, the less being in each case surrounded by the greater – namely, earth surrounded by water, water by air, air by fire, and fire by ether – make up the whole Universe." [35] Stoic ...
The number of protons in the observable universe is called the Eddington number. In terms of number of particles, some estimates imply that nearly all the matter, excluding dark matter, occurs in neutrinos, which constitute the majority of the roughly 10 86 elementary particles of matter that exist in the visible universe. [11]
An atom consists of a small, heavy nucleus surrounded by a relatively large, light cloud of electrons. An atomic nucleus consists of 1 or more protons and 0 or more neutrons. Protons and neutrons are, in turn, made of quarks. Each type of atom corresponds to a specific chemical element. To date, 118 elements have been discovered or created.
According to ancient and medieval science, aether (/ ˈ iː θ ər /, alternative spellings include æther, aither, and ether), also known as the fifth element or quintessence, is the material that fills the region of the universe beyond the terrestrial sphere. [1]
Hence, the formation of helium-4 was delayed until the universe became cool enough for deuterium to survive (at about T = 0.1 MeV); after which there was a sudden burst of element formation. However, very shortly thereafter, around twenty minutes after the Big Bang, the temperature and density became too low for any significant fusion to occur.