Observationally, we don't know the answer to any of these questions. The Universe, as far as we can observe it, only contains information from the final 10 -33 seconds or so of inflation. Anything that occurred prior to that— which includes anything that would tell us how-or-if inflation began and what its duration was— gets wiped out, as far as what's observable to us, by the nature of inflation itself. International Union for Conservation of Nature and Natural Resources and World Wide Fund for Nature In particular, the patterns and magnitudes of the fluctuations that we've discovered in the modern radiation left over from that early, hot, dense state teach us a number of important properties about our Universe. They teach us how much matter was present in dark matter as well as normal matter: protons, neutrons and electrons. They give us a measurement of the Universe's spatial curvature, as well as the presence of dark energy and the effects of neutrinos. According to Hertog, Hawking did not wish to make philosophy, but made philosophy when making quantum cosmology. Hawking wished to unravel the mysteries of physics and Universe and despite his physical condition was able to communicate his optimistic enthusiasm to his research group in Cambridge. The current quantum theory of the Big Bang presently dismisses the theory of multiverse, at least until it is disproved by new telescope observations or other mathematical theories. Whenever we think about anything, we apply our very human logic to it. If we want to know where the Big Bang came from, we describe it in the best terms we can, and then theorize about what could have caused it and set it up. We look for evidence to help us understand the Big Bang's beginnings. After all, that's where everything comes from: from the process that gave it its start.

James P. Allison, Mahlon DeLong, Michael N. Hall, Robert S. Langer, Richard P. Lifton and Alexander Varshavsky (2014) This section may be too long and excessively detailed. Please consider summarizing the material. ( January 2022) Nima Arkani-Hamed, Alan Guth, Alexei Kitaev, Maxim Kontsevich, Andrei Linde, Juan Maldacena, Nathan Seiberg, Ashoke Sen, Edward Witten (2012)

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The book's epigraph is "The question of origin hides the origin of the question", a sentence borrowed by Hertog from the Belgian poet François Jacquemin from Liège. In other words, as also stressed in an interview of Thomas Hertog, "The physical theory of the origin contains the origin of the theory". [3] In a hypertorus model of the Universe, motion in a straight line will return you to your original ... [+] location. If time is like a torus, it may be cyclical in nature, rather than having always existed or coming into existence a finite amount of time ago. We do not, even today, know the origin of time. ESO and deviantART user InTheStarlightGarden

According to the Big Bang, the Universe was hotter, denser, more uniform and smaller in the past. It only has the properties we see today because it’s been expanding, cooling, and experiencing the influence of gravitation for so long. Because the wavelength of radiation stretches as the Universe expands, a smaller Universe should have had radiation with shorter wavelengths, meaning it had higher energies and greater temperatures. In this chapter, Hawking describes the development of scientific thought regarding the nature of space and time. He first describes the Aristotelian idea that the naturally preferred state of a body is to be at rest, and which can only be moved by force, implying that heavier objects will fall faster. However, Italian scientist Galileo Galilei experimentally proved Aristotle's theory wrong with by observing the motion of objects of different weights and concluding that all objects would fall at the same rate. This eventually led to English scientist Isaac Newton's laws of motion and gravity. However, Newton's laws implied that there is no such thing as absolute state of rest or absolute space as believed by Aristotle: whether an object is 'at rest' or 'in motion' depends on the inertial frame of reference of the observer. The Universe could be expanding today because it was contracting in the past, and will contract again in the future, presenting an oscillating solution.Mass and energy are related by the famous equation E = m c 2 {\displaystyle E=mc

For a time, there were multiple competing ideas which were all consistent with the observations we had. This radiation wasn't just the same magnitude everywhere, but also the same in all directions. At just a few degrees above absolute zero, it was consistent with the Universe emerging from an earlier, hot dense state, and cooling as it expanded. Chapter 1: Our Picture of the Universe [ edit ] Ptolemy's Earth-centric model about the location of the planets, stars, and Sun

The different ways dark energy could evolve into the future. Remaining constant or increasing in ... [+] strength (into a Big Rip) could potentially rejuvenate the Universe, while reversing sign could lead to a Big Crunch. Under either of those two scenarios, time may be cyclical, while if neither comes true, time could either be finite or infinite in duration to the past. NASA/CXC/M.Weiss Jeffery W. Kelly, Katalin Karikó, Drew Weissman, Shankar Balasubramanian, David Klenerman and Pascal Mayer (2022) An expanding Universe could have originated from a singular point— an event in spacetime— where all of space and time emerged from a singularity. Hawking then describes Aristotle and Newton's belief in absolute time, i.e. time can be measured accurately regardless of the state of motion of the observer. However, Hawking writes that this commonsense notion does not work at or near the speed of light. He mentions Danish scientist Ole Rømer's discovery that light travels at a very high but finite speed through his observations of Jupiter and one of its moons Io as well as British scientist James Clerk Maxwell's equations on electromagnetism which showed that light travels in waves moving at a fixed speed. Since the notion of absolute rest was abandoned in Newtonian mechanics, Maxwell and many other physicists argued that light must travel through a hypothetical fluid called aether, its speed being relative to that of aether. This was later disproved by the Michelson–Morley experiment, showing that the speed of light always remains constant regardless of the motion of the observer. Einstein and Henri Poincaré later argued that there is no need for aether to explain the motion of light, assuming that there is no absolute time. The special theory of relativity is based on this, arguing that light travels with a finite speed no matter what the speed of the observer is. Our entire cosmic history is theoretically well-understood, but only qualitatively. It's by ... [+] observationally confirming and revealing various stages in our Universe's past that must have occurred, like when the first stars and galaxies formed, and how the Universe expanded over time, that we can truly come to understand our cosmos. The relic signatures imprinted on our Universe from an inflationary state before the hot Big Bang give us a unique way to test our cosmic history. Nicole Rager Fuller / National Science Foundation