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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.
For an object at rest, the energy–momentum four-vector is (E/c, 0, 0, 0): it has a time component, which is the energy, and three space components, which are zero. By changing frames with a Lorentz transformation in the x direction with a small value of the velocity v, the energy momentum four-vector becomes ( E / c , Ev / c 2 , 0, 0) .
In this case, energy can only be exchanged between adjacent regions of space, and all observers agree as to the volumetric density of energy in any given space. There is also a global law of conservation of energy, stating that the total energy of the universe cannot change; this is a corollary of the local law, but not vice versa. [14] [15]
The Vital Question is a book by the English biochemist Nick Lane about the way the evolution and origin of life on Earth was constrained by the provision of energy.. The book was well received by critics; The New York Times, for example, found it "seductive and often convincing" [1] though the reviewer considered much of it speculative beyond the evidence provided.
In The New York Review of Books, Martin Gardner praised The First Three Minutes as "science writing at its best." [5] In The New Yorker, Jeremy Bernstein wrote that "Weinberg builds such a convincing case...that one comes away from his book feeling not only that the idea of an original cosmic explosion is not crazy but that any other theory is scientifically irrational."
The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. [1] The concept of an expanding universe was scientifically originated by physicist Alexander Friedmann in 1922 with the mathematical derivation of the Friedmann equations.
Most of the radiation energy in the universe is in the cosmic microwave background, [58] making up a fraction of roughly 6 × 10 −5 of the total density of the universe. [ 59 ] Two of the greatest successes of the Big Bang theory are its prediction of the almost perfect black body spectrum and its detailed prediction of the anisotropies in ...
The difference in energy production of this cycle, compared to the proton–proton chain reaction, is accounted for by the energy lost through neutrino emission. [22] CNO cycle is highly sensitive to temperature, with rates proportional to T^{16-20}, a 10% rise of temperature would produce a 350% rise in energy production.