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The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. The notion of an expanding universe was first scientifically originated by physicist Alexander Friedmann in 1922 with the mathematical derivation of the Friedmann equations. The earliest empirical observation of the notion of an expanding universe is known as Hubble's law, published in work by physicist Edwin Hubble in 1929, which discerned that galaxies are moving away from Earth at a rate that accelerates proportionally with distance. Independent of Friedmann's work, and independent of Hubble's observations, physicist Georges Lemaître proposed that the universe emerged from a "primeval atom" in 1931, introducing the modern notion of the Big Bang.
Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of fundamental questions about its origin, structure, evolution, and ultimate fate. Cosmology as a science originated with the Copernican principle, which implies that celestial bodies obey identical physical laws to those on Earth, and Newtonian mechanics, which first allowed those physical laws to be understood.
In astronomy, dark matter is a hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravitational effects which cannot be explained by general relativity unless more matter is present than can be observed. Such effects occur in the context of formation and evolution of galaxies, gravitational lensing, the observable universe's current structure, mass position in galactic collisions, the motion of galaxies within galaxy clusters, and cosmic microwave background anisotropies.
General relativity, also known as the general theory of relativity, and as Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics. General relativity generalizes special relativity and refines Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time, or four-dimensional spacetime. In particular, the curvature of spacetime is directly related to the energy and momentum of whatever present matter and radiation. The relation is specified by the Einstein field equations, a system of second-order partial differential equations.
In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation. The opposite change, a decrease in wavelength and increase in frequency and energy, is known as a blueshift, or negative redshift. The terms derive from the colours red and blue which form the extremes of the visible light spectrum. The main causes of electromagnetic redshift in astronomy and cosmology are the relative motions of radiation sources, which give rise to the relativistic Doppler effect, and gravitational potentials, which gravitationally redshift escaping radiation. All sufficiently distant light sources show cosmological redshift corresponding to recession speeds proportional to their distances from Earth, a fact known as Hubble's law that implies the universe is expanding.
In cosmology, the cosmological constant, alternatively called Einstein's cosmological constant, is a coefficient that Albert Einstein initially added to his field equations of general relativity. He later removed it; however, much later it was revived to express the energy density of space, or vacuum energy, that arises in quantum mechanics. It is closely associated with the concept of dark energy.
Observations show that the expansion of the universe is accelerating, such that the velocity at which a distant galaxy recedes from the observer is continuously increasing with time. The accelerated expansion of the universe was discovered in 1998 by two independent projects, the Supernova Cosmology Project and the High-Z Supernova Search Team, which used distant type Ia supernovae to measure the acceleration. The idea was that as type Ia supernovae have almost the same intrinsic brightness, and since objects that are further away appear dimmer, the observed brightness of these supernovae can be used to measure the distance to them. The distance can then be compared to the supernovae's cosmological redshift, which measures how much the universe has expanded since the supernova occurred; the Hubble law established that the further away an object is, the faster it is receding. The unexpected result was that objects in the universe are moving away from one another at an accelerating rate. Cosmologists at the time expected that recession velocity would always be decelerating, due to the gravitational attraction of the matter in the universe. Three members of these two groups have subsequently been awarded Nobel Prizes for their discovery. Confirmatory evidence has been found in baryon acoustic oscillations, and in analyses of the clustering of galaxies.
The ultimate fate of the universe is a topic in physical cosmology, whose theoretical restrictions allow possible scenarios for the evolution and ultimate fate of the universe to be described and evaluated. Based on available observational evidence, deciding the fate and evolution of the universe has become a valid cosmological question, being beyond the mostly untestable constraints of mythological or theological beliefs. Several possible futures have been predicted by different scientific hypotheses, including that the universe might have existed for a finite and infinite duration, or towards explaining the manner and circumstances of its beginning.
The Big Crunch is a hypothetical scenario for the ultimate fate of the universe, in which the expansion of the universe eventually reverses and the universe recollapses, ultimately causing the cosmic scale factor to reach absolute zero, an event potentially followed by a reformation of the universe starting with another Big Bang. The vast majority of evidence, however, indicates that this hypothesis is not correct. Instead, astronomical observations show that the expansion of the universe is accelerating rather than being slowed by gravity, suggesting that a Big Freeze is much more likely to occur. Nonetheless, some physicists have proposed that a "Big Crunch-style" event could result from a dark energy fluctuation.
The observable universe is a spherical region of the universe consisting of all matter that can be observed from Earth or its space-based telescopes and exploratory probes at the present time; the electromagnetic radiation from these objects has had time to reach the Solar System and Earth since the beginning of the cosmological expansion. Assuming the universe is isotropic, the distance to the edge of the observable universe is roughly the same in every direction. That is, the observable universe is a spherical region centered on the observer. Every location in the universe has its own observable universe, which may or may not overlap with the one centered on Earth.
The Big Bounce hypothesis is a cosmological model for the origin of the known universe. It was originally suggested as a phase of the cyclic model or oscillatory universe interpretation of the Big Bang, where the first cosmological event was the result of the collapse of a previous universe. It receded from serious consideration in the early 1980s after inflation theory emerged as a solution to the horizon problem, which had arisen from advances in observations revealing the large-scale structure of the universe.
A cyclic model is any of several cosmological models in which the universe follows infinite, or indefinite, self-sustaining cycles. For example, the oscillating universe theory briefly considered by Albert Einstein in 1930 theorized a universe following an eternal series of oscillations, each beginning with a Big Bang and ending with a Big Crunch; in the interim, the universe would expand for a period of time before the gravitational attraction of matter causes it to collapse back in and undergo a bounce.
The Lambda-CDM, Lambda cold dark matter, or ΛCDM model is a mathematical model of the Big Bang theory with three major components:
- a cosmological constant, denoted by lambda (Λ), associated with dark energy
- the postulated cold dark matter, denoted by CDM
- ordinary matter
The expansion of the universe is the increase in distance between gravitationally unbound parts of the observable universe with time. It is an intrinsic expansion, so it does not mean that the universe expands "into" anything or that space exists "outside" it. To any observer in the universe, it appears that all but the nearest galaxies move away at speeds that are proportional to their distance from the observer, on average. While objects cannot move faster than light, this limitation applies only with respect to local reference frames and does not limit the recession rates of cosmologically distant objects.
An inhomogeneous cosmology is a physical cosmological theory which, unlike the currently widely accepted cosmological concordance model, assumes that inhomogeneities in the distribution of matter across the universe affect local gravitational forces enough to skew our view of the Universe. When the universe began, matter was distributed homogeneously, but over billions of years, galaxies, clusters of galaxies, and superclusters have coalesced, and must, according to Einstein's theory of general relativity, warp the space-time around them. While the concordance model acknowledges this fact, it assumes that such inhomogeneities are not sufficient to affect large-scale averages of gravity in our observations. When two separate studies claimed in 1998-1999 that high redshift supernovae were further away than our calculations showed they should be, it was suggested that the expansion of the universe is accelerating, and dark energy, a repulsive energy inherent in space, was proposed to explain the acceleration. Dark energy has since become widely accepted, but it remains unexplained. Accordingly, some scientists continue to work on models that might not require dark energy. Inhomogeneous cosmology falls into this class.
In physical cosmology and astronomy, dark energy is a proposed form of energy that affects the universe on the largest scales. Its primary effect is to drive the accelerating expansion of the universe. Assuming that the lambda-CDM model of cosmology is correct, dark energy dominates the universe, contributing 68% of the total energy in the present-day observable universe while dark matter and ordinary (baryonic) matter contribute 26% and 5%, respectively, and other components such as neutrinos and photons are nearly negligible. Dark energy's density is very low: 7×10−30 g/cm3, much less than the density of ordinary matter or dark matter within galaxies. However, it dominates the universe's mass–energy content because it is uniform across space.
In mathematical physics, de Sitter invariant special relativity is the speculative idea that the fundamental symmetry group of spacetime is the indefinite orthogonal group SO(4,1), that of de Sitter space. In the standard theory of general relativity, de Sitter space is a highly symmetrical special vacuum solution, which requires a cosmological constant or the stress–energy of a constant scalar field to sustain.
A black hole cosmology is a cosmological model in which the observable universe is the interior of a black hole. Such models were originally proposed by theoretical physicist Raj Kumar Pathria, and concurrently by mathematician I. J. Good.
In cosmology, intensity mapping is an observational technique for surveying the large-scale structure of the universe by using the integrated radio emission from unresolved gas clouds.
Moshe Carmeli was the Albert Einstein Professor of Theoretical Physics, Ben Gurion University (BGU), Beer Sheva, Israel and President of the Israel Physical Society. He received his D.Sc. from the Technion-Israel Institute of Technology in 1964. He became the first full professor at BGU's new Department of Physics. He did significant theoretical work in the fields of cosmology, astrophysics, general and special relativity, gauge theory, and mathematical physics, authoring 4 books, co-authoring 4 others, and publishing 128 refereed research papers in various journals and forums, plus assorted other publications. He is most notable for his work on gauge theory and his development of the theory of cosmological general relativity, which extends Albert Einstein's theory of general relativity from a four-dimensional spacetime to a five-dimensional space-velocity framework.
References
- ↑ Wieland, Carl (3 June 2010). "It's about time. Secular researchers agree: creationist helps develop the most precise clocks in the universe". Creation Ministries International. Retrieved 9 December 2011.
Dr Hartnett (at left) receiving the Cady Award in Newport Beach Calif. on June 3rd, 2010. This award by the IEEE UFFC Society is for the development of ultra-stable cryogenic oscillators and their promotion in metrology labs and VLBI radioastronomy.
- ↑ "Frequency control. Awards and fellows. IEEE International Frequency Control Symposium. The W. G. Cady Award". IEEE. Archived from the original on 9 September 2011. Retrieved 9 December 2011.
- 1 2 3 ScienceNetwork WA (7 December 2008). "Big bang or bulldust?". ScienceAlert. Archived from the original on 7 April 2012. Retrieved 18 November 2011.
A fundamental problem with big bang theory is the weakness of the gravitational force between stars and galaxies. 'Dark' matter – which has never been detected – is needed to explain why so much of the universe (98 percent) is missing, or cannot be seen.
- 1 2 "UWA Staff Profile: Professor John Hartnett". University of Western Australia. Archived from the original on 10 August 2011.
Thesis: 1; Edited book: 1; Refereed Book Chapters: 9; Refereed Journal Papers: 105; Refereed Conference Papers: 3; Conference Papers: 88; Patents: 1 ; Web of Science Citation Report: Total citations: 924; Average: 9.06; h-index: 15
- ↑ Hartnett, John G.; Nand, Nitin R.; Lu, Chuan (2012). "Ultra-low-phase-noise cryocooled microwave dielectric-sapphire-resonator oscillators". Applied Physics Letters. 100 (18): 183501. arXiv: 1202.2206 . Bibcode:2012ApPhL.100r3501H. doi:10.1063/1.4709479. S2CID 118435663.[ permanent dead link ]
- ↑ "University news". University of Western Australia.
- ↑ "Dr John Hartnett, Physics, Cosmology (Australia), Biography". Creation Ministries International . Retrieved 18 November 2011.
- ↑ "Starlight, Time and the New Physics tour with Dr John Hartnett". creation.com. 2012. Archived from the original on 26 April 2009. Retrieved 23 February 2012.
- ↑ "Where Is the Best Clock in the Universe?". arXiv blog. MIT Technology Review. Retrieved 18 November 2011.
The widespread belief that pulsars are the best clocks in the universe is wrong, say physicists.
- ↑ Hartnett, John; Luiten, Andre (2011). "Colloquium: Comparison of Astrophysical and Terrestrial Frequency Standards". Reviews of Modern Physics. 83 (1): 1–9. arXiv: 1004.0115 . Bibcode:2011RvMP...83....1H. doi:10.1103/RevModPhys.83.1. S2CID 118396798.
We have re-analyzed the stability of pulse arrival times from pulsars and white dwarfs using several analysis tools for measuring the noise characteristics of sampled time and frequency data. We show that the best terrestrial artificial clocks substantially exceed the performance of astronomical sources as time-keepers in terms of accuracy (as defined by cesium primary frequency standards) and stability. ...we show that detailed accuracy evaluations of modern terrestrial clocks imply that these new clocks are likely to have a stability better than any astronomical source up to comparison times of at least hundreds of years.
- ↑ Hartnett, John. "Quantized quasar redshifts in a creationist cosmology" (PDF). Retrieved 19 November 2011.
- ↑ Hartnett, John, chapter in Carmeli, Moshe (2008). Relativity: modern large-scale spacetime structure of the cosmos. London, UK: World Scientific Publishing. p. 363. ISBN 978-981-281-375-6 . Retrieved 18 November 2011.
- ↑ Amalfi, Carmelo (18 December 2008). "Keeping time. Science Features (ABC Science)". Australian Broadcast Corporation, abc.net.au. Australian Web Archive. Archived from the original on 14 July 2009. Retrieved 27 November 2011.
...says University of Western Australia physics professor and super-clock maker, John Hartnett. Hartnett is part of a team of scientists...building liquid helium-cooled...clocks...for...radio astronomy.
- ↑ "Moshe Carmeli". Ben Gurion University. Archived from the original on 26 April 2012. Retrieved 27 November 2011.
- ↑ Carmeli, Moshe (2006). Cosmological relativity: the special and general theories of the structure. Danvers, MA, USA: World Scientific Publishing Co. ISBN 981-270-075-7 . Retrieved 25 November 2011.
It was shown by Dr. John G. Hartnett that there is no need to assume the existence of dark matter in the universe.
- ↑ Hartnett, John (2007). Starlight, Time and the New Physics. Creation Ministries International. p. 34. ISBN 978-0-949906-68-7.
'Dark Matter' -today's 'fudge' factor; Technical Appendices: App.1: The large scale structure of the universe does not need 'dark' matter or 'dark' energy; App.6: Light-travel-time problem solved
- ↑ Hopkins, Amanda. "Creation vs Evolution debate on GOD TV". The Way. Retrieved 18 November 2011.
- ↑ Hartnett, John; Williams, Alex (2005). Dismantling the Big Bang. Master Books. Cover. ISBN 978-0-89051-437-5.
As a way of explaining the universe we see, big-bang theory doesn't work. Not only does it lack a credible and consistent mechanism, but even given the credit of every possible doubt, the best it can produce is an expanding cloud of gas.
- ↑ "Temperature compensated oscillator".
